$36,000
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A Look Back at 2016 in Longevity Science

Well, another year passes and here we are again, one step closer to the defeat of aging and age-related disease. Ours is an era of revolutionary progress in biotechnology, and it is starting to show. The past year was characterized by both significant fundraising and significant progress towards the clinical translation of the first complete SENS rejuvenation therapy: clearance of senescent cells from aged tissue. This is hopefully the first of numerous other SENS therapies based on repair of molecular damage to arrive over the next few years. I recently updated my predictions for the near future, looking over the parts of the field that are very close to the making the leap into for-profit startups. These are exciting times.

Regarding senescent cell clearance, I have to open by talking about fundraising. The two topics go hand in hand. Oisin Biotechnologies is the senescent cell clearance company closest to our community of supporters, seed funded back at the end of 2014 by the Methuselah Foundation and SENS Research Foundation, and led by one of the earliest donors to the Methuselah Foundation, someone who has been involved in this community for longer than I have. I've been talking about the need to extend our support for research beyond the laboratory and into startup companies, and in the tradition of doing rather than just talking about doing I participated in one of the funding rounds for Oisin Biotechnologies this year, joined by a number of other supporters. The money is going to good use, but that wasn't the big news in senescent cell clearance funding for 2016, of course. The big news was that UNITY Biotechnology landed one of the largest biotechnology industry funding rounds of recent years: $116 million in order to bring senolytic drugs to the clinic. That and the efforts that led to it will shape this field for years to come.

Over the course of the year, more evidence for the effectiveness of senescent cell clearance rolled in. Teams associated with UNITY Biotechnology showed 25% life extension in normal mice resulting from removal of senescent cells. Other work has shown restoration of function in aged lung tissue, and improved vascular health. New evidence reinforces a role of senescent cells in osteoarthritis, as well as in atherosclerosis, immunosenescence, and diabetic retinopathy. Many other papers have emerged in which researchers link senescent cells in some way to their particular areas of interest in aging. It is safe to say that the broader research community has been well and truly woken up on this topic, and are now engaged in producing a great weight of specific evidence in support of senolytic therapies as a way to delay and reverse numerous processes contributing to age-related disease. The tipping point has passed and things are moving very rapidly now in comparison to past years. How soon before the first senolytic therapies become available via medical tourism, immediately following the first human trials? Not more than a few years, I'd say. A lot of people are running, not walking, to enter this area of development at the moment.

When it comes to fundraising for SENS rejuvenation research, well, there has been a lot of that this year as well. In fact I think the long-standing grassroots of our community is reaching the point of exhaustion on this front. There is only so much water in the well when it comes to charitable support from a single community - and we've certainly given a great deal to the cause. Our community must grow to match the opportunity, but given what is happening for senescent cell clearance, I think this is a very real possibility. In crowdfunding initiatives this year, the Major Mouse Testing Program raised $50,000 for a senescent cell clearance study, and that happened back to back with the SENS Research Foundation raising $70,000 for work on one component of a universal cancer therapy based on blocking telomere lengthening. While that fundraiser was still running, Michael Greve of the Forever Healthy Foundation stepped up to pledge $10 million to SENS research and funding for the startup companies that will emerge from that research. This is the founding donation for the new SENS Project|21 initiative, seeking $50 million to bring significant segments of the SENS portfolio of rejuvenation therapies into readiness for the clinic by 2021. Somehow, in the midst of all of that excitement, the SENS Research Foundation staff found time to once again run the acclaimed Rejuvenation Biotechnology conference in August, bringing together industry and academia to build the necessary bridges for tomorrow's rejuvenation therapies.

Along the way, Ichor Therapeutics raised a funding round to build a therapy from the LysoSENS work of past years: bacterial enzymes turned into drugs to break down specific forms of harmful metabolic waste that contribute to age-related disease. BioViva recieved support from Deep Knowledge Ventures and allied with Sierra Sciences to set up a clinic in their gene therapy efforts. Ambrosia pulled in funds to run a trial of the transfer of young blood plasma to old individuals. The Methuselah Foundation launched their $500,000 research prize for tissue engineering in collaboration with NASA. Further, the founders of CellAge, one of the newer groups to enter the senescent cell clearance space, are currently running a crowdfunding initiative in order to produce better cellular senescence assay and identification technology for the research community.

Last but far from least, the end of year fundraiser for the SENS Research Foundation is coming to a close as I write as well: there is still money left in the various matching funds supplied by Michael Greve, Josh Triplett, Christophe and Dominique Cornuejols, and Fight Aging! This year, we decided to match a year of donations for anyone who signs up as a SENS Patron by pledging monthly donations. This is thinking in the long term, helping to build a steady flow of donations to SENS rejuvenation research, and you'll see more of this initiative in the year ahead.

While the two topics above generate the greatest excitement and attention, there was - of course - way more to the past twelve months in longevity science than senescent cells and fundraising. Gene therapies, for example, are rapidly coming closer to reality, and the first will be available via medical tourism soon enough. Reliable and comprehensive cell coverage remains an important hurdle, though there are promising signs of progress there. The BioViva human study of one reported results for the telomerase gene therapy and, later, the follistatin gene therapy. The only thing stopping you or I from undergoing those same therapies is a matter of knowing who to call and having the necessary funds, but costs will fall rapidly in the years ahead as the number of potential providers rises and data emerges. I'm very enthusiastic about myostatin and follistatin gene therapies, and less so when it comes to telomerase gene therapy. There, I'd like to see results in species other than mice, as their telomere dynamics are significantly different. Many people inside and outside the scientific community are pushing for the development of telomerase therapies to slow aging, however, and at the present adventurous pace we'll see more human data before data in other mammals.

2016 was a big year for the cryonics community, with a great deal of attention from the media, much of surprisingly good, including profiles of supporters and the Russian KrioRus group. Cryonics simply makes sense, and we can hope that more press attention translates into a larger community of supporters making material contributions to the end goal. On that topic, I finally stopped procrastinating and signed up. As it turns out, having a backup plan only works if you actually use it. There are other signs of growth, such as the CryoSuisse initiative, and continued efforts to produce reversible vitrification for the organ transplantation industry. The Brain Preservation Foundation's technology prize was won by a cryonics approach, though not the one currently in widespread use for reasons that have a lot to do with differences in end goal between various interested factions: restoration versus copying and uploading.

Work on the SENS strategy of cross-link breaking is also forging ahead. I wrote up a state of research article early in 2016, and it remains broadly correct for the end of 2016. This research is largely funded by the SENS Research Foundation, and has yet to spread all that far beyond this small number of research groups. In effect it is in much the same position as senescent cell research found itself prior to 2011, looking for the first drug candidate and the first impressive demonstration to gain more interest from outside sources. Fortunately, in this case there is a greater flow of philanthropic funding, so we should see that breakthrough arrive within the next few years. Meanwhile, evidence continues to accumulate for the role played by cross-links in degenerative aging beyond the obvious candidates, including blood vessel stiffening, such as impaired muscle regeneration

On the mitochondrial contribution to aging, this year the SENS Research Foundation in-house team achieved allotopic expression of mitochondrial genes ATP6 and ATP8 - a big advance. The newly public company Gensight Biologics was funded with tens of millions of dollars in venture capital on the basis of doing the same for just one gene, ND4. That work too was supported by the SENS Research Foundation in its earliest stages nearly a decade ago. This is a valuable technology. Now three of thirteen mitochondrial genes can be moved to the cell nucleus: only ten to go in order to remove the contribution of mitochondrial damage to aging. Also of note is research that demonstrates a link between mitochondrial DNA deletions and the progression of sarcopenia, age-related loss of muscle mass and strength - but I am glossing over a good dozen very interesting papers on mitochondrial aging from the past twelve months in order to point out that one.

A number of relevant new organizations have arrived on the scene in 2016. Beyond UNITY Biotechnology and CellAge, mentioned above, the Global Healthspan Policy Institute, focused on lobbying, launched early in the year. On the subject of lobbying, the considerable grassroots efforts among researchers to have aging formally defined as a disease continue, alongside similar efforts to put more of an emphasis on the treatment of aging in definitions provided by influential standards bodies. Separately, the Life Extension Advocacy Foundation continues to expand their footprint in the community. There is a lot of new material at their site; worth a look.

Mitochondrially targeted antioxidants as a means to address inflammatory conditions, and maybe modestly slow the progression of aging or specific age-related conditions, have been in the news. The development of the SkQ series of compounds started in Russia, where it is already used in treatments for inflammatory eye conditions, and has now made its way into European clinical development at MitoTech. There are other lines of mitochondrial antioxidant, such as SS-31, but these are not as far along towards the clinic.

The public view of longevity assurance therapies might be coming around to support for the topic, per a survey conducted this year, provided that such therapies produce extended healthy life rather than extended frailty. In the field, it seems there is a still a considerable need for education, however. People tend to exhibit many incoherent and inconsistent positions when it comes to death, aging, and doing something about both of those topics. The comment sections of social news sites are still filled with people decrying longevity science when news comes to their attention. It is still overall a challenge to raise funds, despite our gains in recent years, and despite the growing interest on the part of various deep pockets. I have to think that the people who claim to want to age and die are failing to think critically about their own personal futures.

In Alzheimer's research, a trial of amyloid clearance via immunotherapy in humans finally worked. The field is littered with failures from the past decade, so this is a big deal. Further, there has been progress towards therapies to clear tau protein from the brain as well, including results from an an initial human trial for safety of a potential immunotherapy. On a different topic, an intriguing study appears to show that memories lost to Alzheimer's pathology can be restored via dendrite regrowth, at last in the early stages. A number of other possibilities beyond immunotherapy have emerged to reduce amyloid levels, such as drawing it out from the brain by clearing it elsewhere, or revisiting the possibility of β-secretase inhibitors. Further, the idea that amyloid builds up because physical drainage channels atrophy will get a test soon, via Methuselah Foundation funding of Leucadia Therapeutics. There are many other types of amyloid in aged tissue, however, and all those will need clearance as well. We might watch Pentraxin Therapeutics as one example of progress in this area. Like so much of this work, it proceeds at a crawl, even following a successful trial back in 2015.

Research on regeneration of an aged thymus, thereby restoring some of the decline in the immune system, continues to move forward. A recent study provided confirmation of benefits resulting from transplantation of a young thymus into an old mouse, for example. In addition to ongoing work on FOXN1 signaling as a possible way to regrow thymus tissue, it was discovered that FGF21 may also be a relevant target. Another team demonstrated that thymic decline correlates with lifespan in dog breeds. Meanwhile, tissue engineers continue to work on the production of working thymus tissue and cell therapies, aiming for the same goal of restoration.

DNA methylation patterns are a promising basis for a biomarker of aging, a test that could be used before and after a putative rejuvenation therapy to evaluate its likely long-term performance. The use of DNA methylation patterns is spreading, and evidence for their potential utility accumulates. Researchers have examined changes early in aging, assessed aging in skin tissue, determined that stroke patients are biologically older than their peers, found that people measured as being biologically older have a greater risk of cancer, and showed that known statistical differences between the life expectancies of various communities also show up in DNA methylation.

Immune system clearance and recreation has tremendous potential as therapy for autoimmunity and many aspects of age-related immunosenescence. This year, researchers demonstrated the ability to cure multiple sclerosis via a fairly simple process of destroying mature immune cells, with no need to attack blood stem cells. This is very promising for the near term development of similar therapies. All that is needed is a less harmful method of targeted cell killing, one that can be safely used by older patients. Fortunately there has been some progress in that direction in the past year, and I think we'll see more in the years ahead. Many methods currently under development in the cancer research community might be converted to this use.

Lastly for this year, a number of short essays fell from the pen to the page. Some might even be worth reading again as we look forward to 2017 and further, faster progress towards therapies to treat the causes of aging:

Metformin Acts through mTORC1

The evidence for metformin to do anything meaningful to longevity in animal studies is fairly ragged - similar studies show a range of results, none of them spectacular, and many of them too small to be significant. It is a marginal candidate for a drug to slow aging when compared to, say, rapamycin, which has much more robust results in animal studies. Further, the whole business of trying to slightly slow aging by tinkering with the ongoing operation of metabolism, slowing the pace at which the cell and tissue damage that causes aging accumulates, is itself an expensive exercise in achieving marginal results. I have to imagine that the reason the TAME human study of metformin and measures of aging exists is not to achieve useful results, but as a form of pressure on the FDA to start accepting treatments for aging. Since metformin has been approved and widely used for decades, the options for rejecting the trial were limited, and once any such trial has been accepted, the next will be easier to push through the established resistance to considering aging as a condition to be treated.

There are a limited number of core mechanisms involved in the link between metabolism and natural variations in longevity, but since all aspects of cellular biochemistry are connected to one another there are any number of ways to influence those core mechanisms. The enormous complexity of molecular biology makes it very hard to map these connections. That work is ongoing now and will be for a long time yet. Thus as a general rule we shouldn't be surprised to learn of newly discovered links between any two of the many approaches demonstrated to modestly slow aging in laboratory species. Here researchers connect metformin with mTOR, the target of rapamycin. mTOR forms two complexes, mTORC1 and mTORC2, and most of the interesting and beneficial effects observed involve suppression of mTORC1. That mTORC2 is suppressed as well is the cause of a number of the harmful side-effects. So there has been some interest in finding ways to target only mTORC1. In that context, it is interesting to see evidence for metformin to be acting in that way, but it doesn't change the basic point that this is all a very marginal exercise with little expected utility for human longevity at the end of the day.

Metformin has been used to treat type 2 diabetes (T2D) for nearly 60 years. It also has potential benefit in cancer prevention and treatment. The class of drugs to which metformin belongs, the biguanides, inhibit cellular growth in a variety of cancer cell lines, particularly in melanoma and pancreatic cancer cells. While it is widely accepted that the mitochondrion is a primary target of metformin, exactly how mitochondrial inhibition by metformin is transduced to the drug's other health-promoting effects, including its anticancer properties, remains unclear. Mitochondrial inhibition by metformin causes energetic stress, which results in activation of the energy sensor adenosine monophosphate-activated protein kinase (AMPK). However, multiple lines of evidence indicate that AMPK is dispensable for metformin's beneficial effects, invoking other major metformin effectors downstream of mitochondria.

The protein kinase mechanistic target of rapamycin complex 1 (mTORC1), which also serves as an energy and nutrient sensor, plays a central role in regulating cell growth, proliferation and survival. Inhibition of mTORC1 activity has been reported in cells in culture treated with metformin, suggesting that reduced TOR activity may be important for the metabolic effects of biguanides. In support of this idea, both metformin and canonical mTOR inhibitors have highly similar effects on the transcriptome, selectively decreasing mRNA levels of cell-cycle and growth regulators. Metformin may inhibit mTORC1 via modulation of Rag GTPases, but the mechanism by which this occurs is uncharacterized. It has been suggested that the pathway that leads to metformin-mediated inhibition of mTORC1 could represent a distinct mechanism of mTORC1 regulation, since no signaling pathway has been identified that connects the mitochondrion to mTORC1 without involvement of AMPK. Whether a mitochondrial-mTORC1 signaling relay plays a role in the action of metformin is still unknown.

As in mammals, metformin promotes health and extends lifespan in C. elegans, raising the possibility of conservation of genetic pathways responsible for metformin's beneficial effects. Using unbiased, iterative genetic screens in C. elegans, we identified a single, central genetic pathway by which metformin regulates growth. We report two elements absolutely required for the anti-growth properties of metformin: the nuclear pore complex (NPC), and acyl-CoA dehydrogenase family member 10 (ACAD10). These two metformin response elements were used to illuminate the major, biological pathway through which metformin induces its favorable effects. Remarkably, this ancient pathway unifies mitochondria, the NPC, mTORC1, and ACAD10 into a single signaling relay that mediates metformin's anti-aging effects in C. elegans and inhibits growth in C. elegans and human cancer cells alike.

Link: http://www.cell.com/cell/fulltext/S0092-8674(16)31667-1

Chimeric Antigen Receptor Therapy Continues to Perform Well in Lymphoma Patients

A patient's T cells can be altered with the addition of chimeric antigen receptors so as to make them aggressively target cancer cells. This form of immunotherapy is one of the best attempted to date, and is producing impressive results in a variety of cancers, starting with leukemia and lymphoma. Here is another example of positive results in a form of lymphoma: the treatment eliminates cancer to produce remission (called "complete response" in the paper) for nearly half of the patients in the small study, as opposed to the one in ten achieved through prior therapies. As the list of side-effects in the paper make clear, however, while this is a considerable improvement there is a still a way to go yet in the production of better cancer therapies.

Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma (NHL) in the United States, accounting for approximately 30%-40% of all cases of NHL. Studies examining outcomes in patients with relapsed/refractory DLBCL show that the response rates to subsequent therapy varies from 14% to 63%. However, relapsed/refractory DLBCL is broadly defined and consists of a heterogeneous patient population. Outcomes are particularly poor in those patients with truly refractory DLBCL, defined as no response to last line of chemotherapy or relapse within 1 year of autologous stem cell transplant (ASCT). A large patient-level meta-analysis of patients with refractory DLBCL found that outcomes in this homogeneous population are significantly worse, with a complete response (CR) rate of 8%, a partial response (PR) rate of 18%, and median overall survival of 6.6 months, indicating a major unmet need for effective therapies for these patients.

Adoptive cell therapy with T cells genetically engineered to express chimeric antigen receptor (CAR) targeting CD19 is a promising approach for treatment of B cell malignancies. A recent single-institution study demonstrated high response rates with an overall response rate of 73% and a CR rate of 55% with anti-CD19 CAR T cells containing CD3ζ/CD28 signaling domains administered in conjunction with low-dose cyclophosphamide conditioning regimen in patients with relapsed/refractory B cell lymphomas. KTE-C19 is an autologous CD3ζ/CD28-based anti-CD19 CAR T cell product that uses the same CAR construct as in the earlier study but is manufactured in a centralized, closed, and streamlined process of approximately 8 days. ZUMA-1 is the first multicenter study evaluating the safety and efficacy of anti-CD19 CAR T cells in patients with refractory NHL. We report here the safety, efficacy, and correlative studies of apheresis product, KTE-C19, and in vivo effects from the phase 1 portion of ZUMA-1.

As of August 2016, the median follow-up time was 9 months. Nine patients were enrolled in the study. Two patients experienced adverse events due to disease progression, discontinued the study, and never received KTE-C19. Seven patients received conditioning chemotherapy and KTE-C19. Patients ranged from 29 to 69 years of age and had received two to four prior lines of therapy. Three were refractory to second-line or later lines of therapy, and four patients had relapsed post-ASCT within 1 year. Despite the small numbers in this study, the overall and complete response (CR) rates were high and durable relative to historical controls. Durable efficacy of the KTE-C19 regimen was observed in patients with rigorously defined chemotherapy refractory disease who had no viable treatment options. Rapid CRs were demonstrated after only 1 month of follow-up in only those four (57%) patients who relapsed after prior ASCT, and responses are ongoing at 12+ months in three of seven (43%) patients. In these three patients, the duration of response with KTE-C19 markedly exceeded the time to relapse after their prior ASCT. This is remarkable, as the expected CR rate in this chemotherapy refractory patient population is 8%, and median survival is 6.6 months with conventional therapies.

Link: http://www.cell.com/molecular-therapy-family/molecular-therapy/fulltext/S1525-0016(16)45375-X

A Conservative View of Senescent Cell Clearance Research and Development

Today I thought I'd point out publicity materials for recent research from yet another group involved in the search for senolytic drugs to clear senescent cells from the body. The position taken is conservative - at least in part - but that is the style of the formal scientific community. Excitement in print is not the done thing. Nonetheless, it is becoming something of a challenge to hold a very conservative position on clearance of senescent cells as one of the foundations for rejuvenation therapies at the present point in time. It takes some rigor to stand up and say that this may still all go nowhere, and much more needs to be done to prove utility. The evidence in animal studies is robust and compelling, and growing more so with every passing month: extended life spans in mice, slowed and reversed mechanisms for age-related diseases, and measures of tissue aging turned back in specific organs. Behind the animal studies lies decades of evidence to support the role of senescent cells in aging and age-related disease in humans.

Maintaining a strongly conservative position until the very last moment is very much a part of the culture of science in our era. No-one is crucified quite so extensively as the scientist who makes bold predictions that then prove incorrect, or even just not entirely correct. The entire scientific community is haunted by the spirits of Pons and Fleischmann, now and for a time yet, but that is merely the easiest of many examples to reach for. The scientist who remains exceptionally and overly conservative, on the other hand, to the point of holding back his or her field, is only pilloried decades down the line, far too late to offer any threat to career and livelihood. People can and should do as they will, following inquiry and progress, but where such incentives exist, it is wise to note their existence while listening to the output of the scientific community. The aging research community in particular was until very recently one in which a great deal of informal policing took place, guiding researchers away from work and public pronouncements on the prospects for the treatment of aging as a medical condition. Who knows how much further along we might have been absent the decades of that stifling culture, thankfully now done away with.

In any case, below find a conservative view for the present state of research and development in the cellular senescence field - which is to say nowhere near as conservative as it would have been a few years ago, or were the author not planning to found a company to develop a senolytic treatment. But a little cold water never hurts for those of us who are enthusiastic about the prospects for this line of research in the near future. There is, after all, still work to be done before the public can travel to overseas clinics to obtain the first therapies with the confidence that comes with initial human trials: the dose-response curve in mice and humans needs fleshing out to set expectations; we'd like to see better alternative senolytic drugs, those that are not chemotherapeutics with interesting side-effects at higher doses; a variety of service companies need to mature and collaborate. All of this will take a few years to settle down into a treatment with known outcomes (measured in terms of proportion of senescent cells removed and short-term side-effects), a low enough cost for the public at large, and that is available via medical tourism in at least a few clinics.

Anti-aging therapies targeting senescent cells: Facts and fiction

It's an exciting time to be an elderly mouse. Researchers believe that by removing senescent cells (cells with a persistent damage response), which naturally accumulate with age, senior rodents can regrow hair, run faster, and improve organ function. This strategy may bring us one step closer to the "fountain of youth," but it's important to be cautious and not hype. The removal of senescent cells, first discovered in the 1960s, received renewed interest in the 2010s as a therapeutic option to combat some aspects of aging. Researchers noticed that these permanently arrested cells accumulate in mature tissue and that some of them secrete factors that are harmful to tissue function and impair their neighboring cells. To explain what causes this noise in the system, a new paper proposes a "senescence-stem lock model" in which the chronic secretion of pro-inflammatory factors by these senescent cells keeps neighboring cells in a permanent stem-like state and thereby prevents proper tissue renewal.

There are three milestones for realistic translation of an anti-senescence approach. Firstly, the proof of concept. Several studies have already addressed whether senescence is a cause of aging and whether its elimination stalls this process. By taking out senescent cells, naturally aging mice lived 25% longer, which is evidence that it could be possible. Secondly, the development of safe therapeutics. Anti-senescent drugs are already being tested, but none of them have yet to be deemed safe because they also target pathways expressed by non-senescent cells. It is likely that this marker will be passed in the near future. Thirdly, reversal of aging. Researchers will need to identify whether clearance of senescence can also be applied retrospectively to counteract features of natural aging that have already manifested. Although aging does seem like it can be stalled through therapeutic compounds, it remains unclear whether age-related diseases can be completely deterred.

"When bringing in a defective car for repairs it is insufficient to remove the rust and broken parts; you also want to replace these. A perfect anti-senescence therapy would not only clear senescent cells, but also kick-start tissue rejuvenation by stimulating differentiation of nearby stem cells. This may be complementary with, for instance, the exciting approaches recently made in the field of transient expression of stem cell factors. I would also advise caution for claiming too much, too soon about the benefits of the fast-growing list of therapeutic compounds that are being discovered. That being said, these are clearly very exciting times, and I am confident we will find applicable anti-senescence treatments that can counteract age-related pathologies."

The Fountain of Youth by Targeting Senescent Cells?

The potential to reverse aging has long been a tantalizing thought, but has equally been considered mere utopia. Recently, the spotlights have turned to senescent cells as being a culprit for aging. Can these cells be therapeutically eliminated? When so? And is this even safe? Recent developments in the tool box to study senescence have made it possible to begin addressing these questions. It will be especially relevant to identify how senescence impairs tissue rejuvenation and to prospectively design compounds that can both target senescence and stimulate rejuvenation in a safe manner.

Given the recent high-profile reports on this topic, the idea of fighting the effects of aging by targeting senescence is at least plausible. However, it is surprising that in decades of modern research, and the roughly half a century in which senescence has been known, nobody has discovered compounds that are beneficial to health by influencing senescence. It is therefore important to separate fact from speculation and temper unrealistic expectations. Targeting senescence may simply not lead to the fountain of youth. That being said, with anti-senescence therapies we are the furthest we have ever been on the path to healthspan extension and restoration of the loss of health experienced during aging.

From ongoing research, it will become clear to what extent senescent cells can indeed inflict a permanent lock in the stemlike state of their surrounding cells and whether targeting senescence may influence tissue repair and rejuvenation. Targeting senescence and stimulating rejuvenation might at least potentially counter individual age-related diseases and in doing so, we might be getting closer to achieving the goal of developing a 'therapy' against aging. Coming years will undoubtedly see exciting developments to come.

Abstract 2843: TASC1, a selective anti-senescence therapeutic which potently and selectively counteract resistance to chemo- and radiotherapy

Cellular senescence, induced by chemotherapy and radiotherapy, can drive therapy resistance in vivo. Senescence is a tumor suppressive mechanism, but senescent cells can secrete a range of proteins that ironically promote tumor growth, migration and metastazation and therapy resistance. Recent evidence has shown that genetic removal of senescent cells indeed causes a strong reduction in tumor growth and metastasis formation. Unfortunately however, therapeutic options to remove senescent cells are currently lacking. Here, we show the development and optimization of a biochemical compound, TASC1, that potently and selectively kills senescent cells in vitro and in vivo and lowers organ toxicity in a mouse model employed to address the off-target effects of cancer therapy.

Chondrocyte Cell Death in Osteoarthritis

Researchers here review what is known of mechanisms contributing to the death of chondrocyte cells in aged joint cartilage. The loss of cartilage is characteristic of osteoarthritis, and given the prevalence of this condition in old people, there is considerable interest in finding ways to halt this process. Like all things in the biology of aging, it is far from simple and far from completely mapped, however. This paper omits mention of the likely role of cellular senescence in the development of osteoarthritis, something that seems much more relevant now that means of removing senescent cells are emerging, so you might treat this publication as a companion piece to another paper on that topic published earlier in the year.

Osteoarthritis (OA) is the most common chronic joint disease. OA pathophysiology was, for a long time, attributed to biomechanical constraints exerted on weight-bearing articulations (e.g., knees, hips). However, metabolic factors are also well recognized as mediators in the onset of OA. Adipose tissue can act as an endocrine organ, releasing bioactive molecules, such as pro-inflammatory cytokines, of which levels can be significantly and positively correlated with cartilage degradation in OA patients. OA is characterized by a progressive breakdown of articular cartilage, involving the remodeling of all joint tissues (bone, synovium, ligaments) with the appearance of osteophytes, synovial inflammation, subchondral bone thickening, and in fine joint space narrowing. Cartilage degradation constitutes one of the prominent hallmarks of the disease.

Articular cartilage is a conjunctive tissue composed of only one cell type, chondrocytes, enclosed in a self-synthesized extracellular matrix (ECM). These specific cells represent approximately 1% of total cartilage volume and are responsible for matrix composition and integrity, thereby conferring to cartilage its functions of mechanical support and joint lubrication. Histochemistry analyses have demonstrated the formation of chondrocytes clusters, the presence of irregular surfaces, cartilage volume loss, and matrix calcification in OA cartilage compared to normal cartilage. These changes in cartilage structure are linked to the alteration of molecular components of ECM. Distribution of the collagen II network is modified, being uniformly distributed throughout the normal cartilage layers, but at a decreased level in OA-degenerated areas and at an increased level in chondrocytes clusters.

Chondrocytes are quiescent cells that rarely divide under physiological conditions: Adult human cartilage is a post-mitotic tissue displaying virtually no cellular turnover. Moreover, the ECM is not innerved nor vascularizated, thereby avoiding new cell supply to compensate for potential cellular loss. As a consequence, phenotypic stability, anabolic/catabolic balance activity, and survival of chondrocytes are crucial for the maintenance of proper articular cartilage. During the course of OA, all of these criteria are modified. Compelling studies report the presence of empty lacunae and hypocellularity in cartilage with aging and OA progression, suggesting that chondrocyte cell death occurs and participates to OA development. However, the relative contribution of apoptosis per se in OA pathogenesis appears complex to evaluate. Indeed, depending on technical approaches, OA stages, cartilage layers, animal models, as well as in vivo or in vitro experiments, the percentage of apoptosis and cell death types can vary. Although an excess of autophagy can lead to cell death, the current view is that the trigger of autophagy in chondrocytes aims to avoid cell death, especially in the early stages of OA.

Currently, there is no treatment for a full stop of OA progression. Therefore, preventing, limiting, or delaying chondrocyte cell death, in order to maintain cartilage matrix integrity, might constitute a tempting approach. Caspase inhibitors are the most studied among all of the apoptosis regulators in OA. However, a tight control of the delivery site of these anti-apoptotic agent should be required (limited to the cartilage injury site) in order to avoid the risk of systemic malignancies. In addition, studies have shown that chondrocytes shifted towards necrotic cell death, suggesting that cells trying to avoid apoptosis paved the way for another dying process, such as necrosis. Minimizing oxidative stress and preserving mitochondria integrity could constitute an alternative approach. Antioxidants have demonstrated anti-apoptotic and anti-OA effects in rat and mouse models. Promoting autophagy could also indirectly act on removing defective mitochondria and the associated oxidative stress. Moreover, as key autophagic proteins were found to be decreased in aging and OA cartilage, restoring autophagy could be considered to delay OA development. A better molecular delineation of apoptotic and autophagic processes may help in designing new therapeutic options for OA treatment.

Link: http://www.mdpi.com/1422-0067/17/12/2146/htm

Calling for a Closer Examination of Mitochondrial Biochemistry in the Aging Brain

Mitochondrial dysfunction is strongly associated with the progression of aging, and forms of damage to mitochondrial DNA are one of the contributing causes of aging. Here, researchers review what is known of the changes that occur in mitochondrial biochemistry in the aging brain, and call for further work in this area to clarify the many specific uncertainties. Despite these uncertainties, there is more than enough evidence to move forward with attempts to repair mitochondrial DNA damage, as this may well remove the mitochondrial contribution to degenerative aging and age-related disease even in the absence of a complete understanding of all of the processes involved. There is a very reasonable expectation of significant gains to result from this work, justifying greater efforts in this area of development.

The mitochondrion is a ubiquitous intracellular organelle instrumental to eukaryotic existence. It is the major intracellular site of oxygen consumption and producer of the high energy molecule adenosine triphosphate (ATP). Mitochondria carry out tasks besides energy production, including cellular homeostasis and signalling, iron processing, haem and steroid synthesis, protein and lipid biosynthesis and apoptosis. These organelles are extremely dynamic and variable, capable of responding to numerous stimuli (including temperature, nutrients, hormones, exercise and hypoxia); they initiate the production of new mitochondria and their selective removal. The brain, per gram, has the highest demand for glucose than any other tissue. Brain function is entirely dependent on glucose and oxygen from the carotid and vertebral circulation. Glucose oxidation followed by oxidative phosphorylation is accountable for the vast majority of ATP generated in the brain. Brain energy metabolism declines with age. Our own group and others have observed this decline to be clinically homogenous in most brain regions. This metabolic change is considered to be a feature of the ageing phenotype as well as age-related neurodegeneration, where there is mounting evidence supporting the role of dysfunctional mitochondria in their progression.

As our understanding of ageing has progressed mitochondrial function has come to the forefront as pivotal to the aged phenotype. Classical theories, including the mitochondrial free radical theory of ageing (MFRTA), have led the field. According to the MFRTA an accumulation of oxidative damage, caused by mitochondrial free radicals, is the driving force behind ageing. However, this theory conflicts with growing evidence from animal models. Species comparison between the long lived naked mole rat and short lived mouse indicates little difference in the production of ROS between species and no age-dependent variation in antioxidant enzyme expression. This suggests that mitochondrial ROS may act as signalling molecules, prolonging maximum lifespan. MFRTA also fails to fully explain the functional brain mitochondrial deficits that occur with age. These deficits include reduced respiration, dynamic changes in shape and size, activation of permeability transition pore and loss of membrane potential. Although functional studies have gone some way to identifying these mitochondrial changes, there is variability found in the direction and extent to which these differences occur. There is even evidence to suggest that oxidative phosphorylation activity may in fact increase with age. There are similar inconsistencies which exist for the role and the activity of mitochondrial antioxidants, fusion and fission dynamics and other mitochondrial proteins with age. Profiling of mitochondrial protein expression in tissues from different ages can add molecular insight, which in conjunction with functional studies can be a powerful approach towards unravelling this complexity.

With evidence pointing toward a pivotal role of mitochondria in neurodegenerative disease and the aged phenotype, an understanding of the changes to the proteome is warranted. Mitochondrial proteomic alteration in brain ageing is clear, however the directionality and extent of these alterations is not. The application of quantitative proteomics to mitochondria is timely to more comprehensively investigate these changes. With the advent of new proteomic technologies, bringing greater reproducibility and accuracy, the field of mitochondrial proteomics is open-ended and improved clarity of the mitochondrial changes that occur in the brain with age is expected in the near future.

Link: https://dx.doi.org/10.18632/aging.101131

A Look at Ascendance Biomedical, Packaging Medical Tourism for Longevity Therapies

Ascendance Biomedical is a fairly new venture, still in the early stages of formalizing its structure and agenda. It is focused on the twofold path of (a) establishing patient-funded trials of potentially useful therapies in the longevity science space, and (b) packaging participation in trials and later purchase of therapies via medical tourism, bundling all of the complications into a single product. The people involved overlap with the principals of the Global Healthspan Policy Institute, and are fairly well connected in our community. The organization is tackling just a few types of therapy to get started, gaining experience in how best to go about this class of project.

Now, I will be the first to say that their initial and current work on trials and medical tourism is in areas that are not all that interesting to me, in that I don't believe they will have any great impact on aging: an established but not widely adopted cancer therapy and a hormone therapy approach to restoring ovarian function in older women. I'm not singling out Ascendance Biomedical in saying this. A number of similar initiatives are taking place in the aging research community, such as the Ambrosia trial for plasma transfusion, the TAME trial for metformin, and the TRIIM trial for thymus rejuvenation. What these all have in common is that if you think that aging is caused by accumulated molecular damage, then little should be expected to emerge from these efforts: these are hormone treatments, supplements, and existing drugs, or new therapies that seem at best to fall into much the same region as first generation stem cell transplants, in that they alter signaling in old tissues in some way that helps a little. They are not damage repair. I think we can do much better than all of this, via the SENS approaches. In any case, the point is not Ascendance Biomedical today, it is the potential Ascendance Biomedical of a few years from now.

Ascendance Biomedical

Ascendance Biomedical is a novel corporation founded with an ambitious goal in mind: We want to make it easier for everyone to gain access to life-saving treatments - without the hassle. We are a team of physicians, scientists and entrepreneurs unified in the mission to save and improve lives. Ascendance Biomedical provides products and services which enable our customers to access the most cutting-edge biomedical technologies and treatments in the world. Working with clinics, physicians and scientists all over the world in all regulatory zones, we help you get the care that you need. We not only provide medical care and treatment, we also assist with flights, accommodation, travel instructions, the processing of medical records, direct connection with medical personnel upon arrival, analysis of your case to get you the best price with local physicians and - most importantly - set you up to receive the required treatments and interventions for your condition. Ascendance Biomedical offers not just products, but all-inclusive healthcare solutions for patients worldwide.

Medical tourism for senolytic treatments to clear senescent cells - one of the SENS programs for the treatment of aging - is on the Ascendance Biomedical agenda for the near future, and this is a very plausible exercise given the present state of the science. All of the existing senolytic drugs are very well characterized, new ones are being discovered among compounds easily ordered from chemical suppliers, and thus the costs to set up trials are reasonable when considered in the grand scheme of things. What is needed is an organization that specializes in rolling out such trials and then managing easy access to the therapies via medical tourism thereafter. Once such an organization exists, and is well connected in our community, then all further SENS therapies will have a much more cost-effective path to initial human trials and the clinic as soon as safety is proved. That will be important, as none of us will want to wait around for the ten years it will take someone with deep pockets to fight their way past an uncaring FDA. As for stem cell therapies, that can happen in parallel with public access to treatments outside the US.

When looking at the near future of rejuvenation biotechnology, you have to look beyond the therapies themselves and see the development of an ecosystem of companies sympathetic to the SENS vision for the medical control of aging. The first therapies are not only important for the treatments themselves, but also for the organizations that are created in the process of development, and which continue onward afterwards to take on new challenges. We need companies like Ichor Therapeutics that come attached to an established laboratory service business. We need companies like Oisin Biotechnologies doing the work of building the therapies. We need startup incubators and incubator-like organizations like the Methuselah Foundation is becoming. We need the angels and venture capitalists who think SENS is a great idea. We need the non-profits that help to push the research into readiness, such as the SENS Research Foundation. And of course, we need efforts like Ascendance Biomedical that focus on building a better, smoother, more efficient bridge to the clinic. All of these components in the ecosystem are emerging, piece by piece, thanks to a great deal of hard work beyond the scenes.

The medical tourism industry has only grown since stem cell therapies first became available, and since the regulatory burden in the US and Europe continues to increase. More regulation means more costly medicine, and worse medicine - the gap between what is possible and what is allowed continues to grow as it takes ever longer for research to be approved by the FDA and other regulatory bodies. Yet in many ways the medical tourism industry is very immature. There is little in the way of service organizations, reviewers, independent assessors and standards bodies. When you choose medical tourism, you must undertake a lot of work yourself, and will probably find yourself wishing that someone just offered simple, sensible packaged products for therapies of interest. This lack of market maturity may be a consequence of the fact that, in the grand scheme of things, very few people actually purchase any given therapy on any given day. The healthy, or at least those not in very dire straits, vastly outnumber the sick and the damaged. The advent of therapies like senescent cell clearance using senolytic drugs changes the whole economic picture here, however. This is a product that can be sold to everyone over the age of 40, once every few years. The pool of potential customers is far, far greater than that for a therapy for any given age-related disease, and the economics mean that yes, we should absolutely see the emergence of a competitive marketplace for packaged services like those offered by Ascendance Biomedical.

Dopamine D4 Receptor Allele Correlates with Longevity

The standard way to determine whether a genetic variant is associated with longevity is to look at its prevalence in the population at various ages. If the relative proportion of the variant increases in the surviving population, then that may be because it is having an impact on survival. Only two genes have variants that robustly appear to associate with longevity in multiple study populations, however, APOE and FOXO3A, and even there the size of the effect is small. The picture that has emerged from genetic studies of longevity and aging to date is one of thousands of tiny interdependent influences, interacting with the environment and one another, such that correlations in one study population near always fail to show up in another, even when both studies are carried out in the same part of the world. Still, the studies continue, with researchers now digging deeper into areas of genetic analysis that were previously skipped for technical reasons. Here is a recent example, in which researchers do manage to replicate a finding of association with longevity for a variant of the dopamine D4 receptor:

Age at death in adulthood has a heritability of approximately 25%. According to a recent review of genome-wide association studies (GWAS) APOE and FOXO3A gene variants are associated with longevity. Although association of other genetic polymorphisms did not reach the level of genome wide significance, identified pathways and genetic signatures have been shown to be important in longevity. Inheritance of long life span seems to be rather complex, with modest individual genetic effects, along with significant gene-environment interactions. Based on a study of exceptional longevity, genetic factors seem to be even more important where familial clustering of extreme old age is robust. These individuals might lack some of the risk factors related to various diseases, and at the same time carry protective genetic variations against basic mechanisms of age-related illnesses, also referred to as 'longevity enabling genes'.

It is important to note that due to technical reasons GWAS and SNP studies on longevity have not investigated any variable number of tandem repeat variations (VNTR) in association with longevity. It has been proposed that a specific VNTR variant, the 7 repeat allele of the dopamine D4 receptor gene (DRD4), could be an important factor in extreme longevity, because it plays a major role in the brain's dopaminergic functioning. Surviving participants of a 30-year-old population-based health survey (N = 310, age range 90-109, mean age: 95.2 years) possessed a 66% higher rate of 7 repeat allele carriers as compared to that of an ancestry-matched young population (N = 2902, age range 7-45). In addition, this association was far more pronounced in females (there were 39.3% allele 7 carriers in the old vs 21.9% in the young population) as compared to males (29.7% in the old vs. 21.9 in the young population). There is supporting evidence from animal studies of this gene: DRD4 knock-out mice lived 7-9.7% shorter and showed reduced spontaneous locomotor activity, as compared to those with functional DRD4 genes. Also, while the wild type mice showed clear beneficial effects of an enriched environment on lifespan, the DRD4 knock-out mice did not a show lifespan increase when reared in an enriched environment.

Initial association result of the DRD4 VNTR 7 repeat allele and longevity have not yet been replicated to date, which would be reassuring given recent arguments regarding the critical importance of replication in genetic studies. The major goal of the present study was to test association of the DRD4 VNTR 7 repeat allele and longevity using continuous age groups. We analyzed association of the DRD4 VNTR with longevity. Association analyses of continuous age groups using genotype data from 1801 Caucasian participants from 18 to 97 years of age showed a significant increase of allele 7 carriers with age. Interestingly, from age 18 to 75 ratio of those carrying the 7-repeat allele increased progressively from 29.5% to 46.9% in the tested age groups, however, in the older age groups the proportion of allele 7 carriers dropped intensively (44.4% in those between 76-85 years and 31% in the 86-97 age group). This "drop" might be due to the relatively small sample size of the age groups, but might also point to the fact that relative importance of environmental, genetic and stochastic determinants of survival vary with age. Association of the DRD4 gene variants with longevity fits well with the assumption that inheritance of longevity is complex, with modest individual genetic effects interacting with each other as well as with the environment. We propose that the DRD4 allele 7 could be a "longevity enabling genetic variant," protecting against basic mechanisms of age-related illnesses, but the precise manner in which this is accomplished is unclear at this point.

Link: http://dx.doi.org/10.1371/journal.pone.0167753

More in the Debate Over Whether or Not Aging Should be Called a Disease

Here I'll point out a recent objection to the formal classification of aging as a disease, which seems to merge at the edges with an objection to treating aging at all, or an objection to aiming high, or the belief that significant progress in this field is not plausible. The latter is, sadly, a common position in the field of aging research. At the very least there is a strong separation of the ideas of aging and disease, which doesn't seem to me to be justified. Aging and age-related disease are only made separate in concept, divided by the names we give to various states and processes. At the low level in our cellular biochemistry it is the same forms of damage that give rise to what is called normal aging and what is called an age-related disease. Matters of degree only separate "healthy" (in decline, less than they were) senior individuals from patients diagnosed with specific age-related diseases.

Is aging a disease? Mutaz Musa answers this question in the affirmative. In response to his article, we suggest that, aside from containing fundamental logical flaws, Musa's argument produces a simplistic picture of the complexities of aging, both as a concept and as an actual phenomenon. While the author's opinion appears to be driven by a sincere desire to optimize people's lives, his approach might in fact be counterproductive: by pathologizing aging, he creates more, not less, challenges to ascribe meaning to age-related physical decline. The questions raised in Musa's piece are nonetheless thought-provoking, as he confronts assumptions about what constitutes disease and what causes aging. In particular, Musa asks us - researchers who study the various processes of aging - to consider how we define aging, disease, and the causes and effects that link these phenomena.

There are logical flaws in Musa's opening statements. "No longer considered an inevitability, growing older should be and is being treated like a chronic condition," he writes. This proclamation contains argumentative entanglements that are common in the field of aging research, and which should be considered carefully. Musa's first claim, that "growing older is no longer considered an inevitability," only makes sense if you consider "growing older" not as a descriptive term for the latter stages of the time that passes from birth to death, but as another way of denoting the state of becoming frail, diseased, mentally and physically infirm, and so on. Aging researchers have found that such decline is not an inevitable occurrence associated with aging (backed up and famously articulated in research frameworks such as Successful Aging). But stating that some or all of these effects may be avoided is not the same as saying that "growing older is no longer considered an inevitability."

Another illustrative example of shifts in logic and meaning occurs when Musa writes about age-related changes in the body, arguing that some of these show "that perfectly normal processes that are critical to survival will quite naturally lead to disease. In a biological sense, the mere passage of time is pathological." Here, Musa turns the fact that some routine processes lead to pathology into an argument that these processes are, therefore, pathological. That some processes lead to pathology does not mean that these processes are responsible for disease. Even a process like the production of reactive oxygen species (ROS) through mitochondrial function does not automatically lead to dangerously damaged DNA - it can, but only if there are no antioxidants available, and if DNA repair mechanisms are compromised in some way. We don't define smoking as a disease, we define lung cancer as a disease: smoking is a risk factor, but does not always lead to lung cancer. By collapsing causal risk factors and pathology into one, aging researchers will not become better equipped to deal with the complexity of either part. Nor will anyone benefit from a pathologization of bodily processes that happen in everyone, at all times.

Further, to propose, as Musa does, that if some process over time leads to pathology, then "the mere passage of time" in a biological sense is pathological, is an inductive fallacy. A fallacy that ignores the multiple processes and effects happening in the body over time, all the time, where some have effects most people want, and some do not. Regardless of our abilities to traverse our senior years illness free, we will all, eventually, die. Conflating aging and illness, however, weakens our ability to impart meaning to such inevitability. It seems that while Musa comes to represent an approach to aging that will undoubtedly attract research funding that will help scientists find ways to allow people to live physically healthier lives, it is also an approach that seeks to reduce complex issues to more simple models, thus creating an illusion - or at least the hope - of control and of biotechnological solutions to issues that also have existential and social aspects. This approach overemphasizes the importance of prolonging life at the expense of coming to terms with the possibilities of frailty and various forms of decline - not to mention death - in later life. This will not create less suffering. It will create unrealistic expectations of future scientific mastery of the human condition, telling us that frailty and decline should be avoided at all costs. This is neither a healthy psychological reaction to frailty and decline, nor will it ultimately lead to anything but individual disappointment and a mistrust of a science that promises more than it can deliver.

Link: http://www.the-scientist.com/?articles.view/articleNo/47849/title/Opinion--Aging--Not-a-Disease/

Nrf2 Improves Clearance of Damaged Proteins Associated with Neurodegeneration

The protein Nrf2 shows up in a number of places in the study of aging and related aspects of cellular biochemistry. Higher levels of Nrf2 appear to correlate well with longer species lifespan, at least among mammals in the wild, but this is also arguably the case in the various genetically engineered lineages of mice, worms, and flies that exhibit longer lifespans. Until recently the main focus of research into the role of Nrf2 has been the regulation of antioxidants as a response to cellular stress, as occurs due to the metabolic demands of exercise, for example. Of interest here is that Nrf2 levels decline with age, which is probably a phenomenon that we'd be better off without; it is one of many, many candidates for the mechanisms of aging that float somewhere between the root causes and the final consequences in the long chain of cause and effect that produces degenerative aging as we know it.

In the research linked below, the authors expand the bounds of influence for Nrf2, linking it to some of the mechanisms of cellular housekeeping that strive to remove damaged proteins. In particular, it seems influential in the matter of a few proteins associated with neurodegenerative conditions, such as α-synuclein in synucleinopathies like Parkinson's disease. Greater cellular maintenance activity is a common theme in many of the methods that have been demonstrated to modestly slow aging in laboratory species. When cells have less damage at any given moment in time, that damage has less of a chance to cause further downstream harm. There are many researchers who place natural mechanisms of quality control and damage repair at the center of all methods of slowing aging via metabolic and genetic alteration discovered to date, and evidence such as calorie restriction requiring the maintenance processes of autophagy in order to extend healthy life makes this a fairly compelling argument.

If greater levels of Nrf2 indeed produce greater housekeeping efforts in the clearance of damaged proteins, then that new knowledge fits well into this bigger picture given what is known to date. Where is this all going, however? Despite a good many years during which numerous researchers have argued for the importance of increased cellular maintenance, there has been next to no concrete progress towards therapies based on this principle. I was noting calls to action on this topic a decade ago, and I am by now somewhat surprised at the continued lack of motion towards the clinic in this part of the field, despite a growing catalog of research very much like the results presented here.

Single Protein May Hold Secret to Treating Parkinson's Disease and More

At their root, neurodegenerative diseases, such as Parkinson's, Huntington's, Alzheimer's, and amyotrophic lateral sclerosis (ALS), are triggered by misbehaving proteins in the brain. The proteins misfold and accumulate in neurons, inflicting damage and eventually killing the cells. In a new study, researchers used a different protein, Nrf2, to restore levels of the disease-causing proteins to a normal, healthy range, thereby preventing cell death. The researchers tested Nrf2 in two models of Parkinson's disease: cells with mutations in the proteins LRRK2 and α-synuclein. By activating Nrf2, the researchers turned on several "house-cleaning" mechanisms in the cell to remove excess LRRK2 and α-synuclein. "Nrf2 coordinates a whole program of gene expression, but we didn't know how important it was for regulating protein levels until now. Overexpressing Nrf2 in cellular models of Parkinson's disease resulted in a huge effect. In fact, it protects cells against the disease better than anything else we've found."

In the study, the scientists used both rat neurons and human neurons created from induced pluripotent stem cells. They then programmed the neurons to express Nrf2 and either mutant LRRK2 or α-synuclein. The researchers tagged and tracked individual neurons over time to monitor their protein levels and overall health. They took thousands of images of the cells over the course of a week, measuring the development and demise of each one. The scientists discovered that Nrf2 worked in different ways to help remove either mutant LRRK2 or α-synuclein from the cells. For mutant LRRK2, Nrf2 drove the protein to gather into incidental clumps that can remain in the cell without damaging it. For α-synuclein, Nrf2 accelerated the breakdown and clearance of the protein, reducing its levels in the cell. "I am very enthusiastic about this strategy for treating neurodegenerative diseases. We've tested Nrf2 in models of Huntington's disease, Parkinson's disease, and ALS, and it is the most protective thing we've ever found. Based on the magnitude and the breadth of the effect, we really want to understand Nrf2 and its role in protein regulation better."

Nrf2 mitigates LRRK2- and α-synuclein-induced neurodegeneration by modulating proteostasis

The prevailing view of nuclear factor erythroid 2-related factor (Nrf2) function in the central nervous system is that it acts by a cell-nonautonomous mechanism to activate a program of gene expression that mitigates reactive oxygen species and the damage that ensues. Our work significantly expands the biological understanding of Nrf2 by showing that Nrf2 mitigates toxicity induced by α-synuclein and leucine-rich repeat kinase 2 (LRRK2), by potently promoting neuronal protein homeostasis in a cell-autonomous and time-dependent fashion. Nrf2 accelerates the clearance of α-synuclein, shortening its half-life and leading to lower overall levels of α-synuclein. By contrast, Nrf2 promotes the aggregation of LRRK2 into inclusion bodies, leading to a significant reduction in diffuse mutant LRRK2 levels elsewhere in the neuron.

Disruption of protein homeostasis is an emerging theme in Parkinson's disease pathogenesis, making mechanisms to reduce the accumulation of misfolded proteins an attractive therapeutic strategy. By identifying the stress response strategies activated by Nrf2, we also highlight endogenous coping responses that might be therapeutically bolstered to treat Parkinson's disease.

Results from the Gensight Biologics Trial of ND4 Allotopic Expression

Gensight Biologics is the company that emerged from the first viable line of allotopic expression research, in part supported some years ago by the SENS Research Foundation and the charitable donations of our community. Allotopic expression is the name given to gene therapy to copy mitochondrial genes into the cell nucleus, providing a backup source of proteins. Since mitochondrial DNA damage resulting in loss of function for genes involved in packaging energy store molecules is one of the causes of aging, allotopic expression of all thirteen genes used in this process will remove this contribution to degenerative aging and age-related disease. This is challenging work and still in progress - only three of these genes have had allotopic expression demonstrated to date. Along the way, however, these incremental successes can be used to cure inherited mitochondrial disorders caused by the loss of one specific mitochondrial gene, such as the blindness of Leber's Hereditary Optic Neuropathy. That is the initial goal for the Gensight Biologics staff. They are well funded these days, having gone public earlier this year, and are making good progress, as this latest trial data shows. Their GS010 product is the vector for introducing suitably modified ND4 into the cell nucleus:

GenSight Biologics, a biopharma company that discovers and develops innovative gene therapies for neurodegenerative retinal diseases and diseases of the central nervous system, today reported additional promising results after 78 weeks of follow-up in its Phase I/II clinical trial. These results confirm the favorable safety and tolerability profile of GS010, while demonstrating sustainable visual acuity improvement in patients with Leber's Hereditary Optic Neuropathy (LHON). Each cohort of three patients was administered an increasing dose of GS010 through a single intravitreal injection in the eye most severely affected by the disease. Recruitment was completed in April 2015 and long-term follow-up is ongoing. These patients had an average onset of disease of 6 years at the time of treatment. At baseline, both treated and untreated eyes had an off-chart median visual acuity.

At 78 weeks post-injection, the mean change of visual acuity from baseline in the treated eyes of all patients* was -0.61 LogMAR, equivalent to a mean improvement of +30 ETDRS letters. For all untreated eyes at week 78, the mean change from baseline was -0.31 LogMAR, equivalent to a mean improvement of +15 ETDRS letters. This provides a treatment effect (mean difference between treated worse-seeing and untreated best-seeing eyes) of +15 letters in favor of treated worse-seeing eyes. More interestingly, in patients with an onset of vision loss of less than 2 years at the time of treatment, a mean gain of +32 ETDRS letters (-0.63 LogMAR) was observed in treated eyes, while a mean gain of +12 ETDRS letters (-0.23 LogMAR) was observed in untreated eyes, resulting in a difference of 20 ETDRS letters in favor of treated eyes. The patient group with vision loss for 2 years or less at the time of injection demonstrated a treatment effect in favor of the treated eye of increasing magnitude from week 36 onwards.

Link: http://www.gensight-biologics.com/index.php?mact=InvestorNews,cntnt01,detail,0&cntnt01item_id=48&cntnt01returnid=37

An Effort to Equip Macrophages with Bacterial Enzymes to Prevent Atherosclerosis

This research is an example of the LysoSENS methodologies pioneered by the SENS Research Foundation today, and in past years by the Methuselah Foundation. The approach involves mining the bacterial world for enzymes capable of breaking down resistant metabolic waste in human cells, so as to remove the contribution of that waste to degenerative aging. In this case the target is the lipids that build up in blood vessel walls and overwhelm macrophages that arrive to deal with the problem. The macrophages become foam cells and die, which only produces more damage and attracts more macrophages to try to clean it up. Over time this turns a small area of damage and inflammation into a growing plaque of fatty waste and dead cells, narrowing and weakening the blood vessel. If macrophages could be made resistant to this fate, it would remove a major contributing cause of atherosclerosis, a condition that is ultimately fatal when plaques rupture and block or break major blood vessels as a result.

Atherosclerotic cardiovascular disease (CVD) is the leading cause of death in the United States. CVD originates from aberrations in normal lipid metabolism (some genetic, some lifestyle choices) that result in elevated plasma lipoproteins (principally LDLs) and/or low levels of high-density lipoproteins (HDLs). For many people, CVD is an age dependent, progressive disease that is largely undetected or ignored until an event (i.e. myocardial infarction or stroke) occurs in the later stages of disease. Therefore, current therapies focus on preventing a second event (or a primary event in high risk individuals) by reducing the circulating levels of LDLs and/or increasing HDLs.

However, at a biochemical level the inability of macrophages to degrade the cholestane ring of cholesterol is a fundamental component of CVD. If macrophages had the ability to degrade cholesterol, they would not become engorged with cholesterol/cholesterol esters and elicit the maladaptive immune response that leads to the onset and progression of atherosclerosis. Recently, studies of Mycobacteria survival in human macrophages revealed a surprising observation. Mycobacteria feed on cholesterol while contained in the phagosomes of macrophages. Importantly, two enzymes that catalyze cholestane ring opening have been identified. We plan to test the hypothesis that genes encoding enzymes identified in bacteria can be humanized and used to transformation human monocyte derived macrophages, enabling the degradation of phagosome-cholesterol. The main objectives are to: 1) humanize bacterial genes encoding key ring opening enzymes, 2) develop an innovative expressions systems to regulate the expression of these genes in response to changes in cellular levels of cholesterol, and 3) characterize the production and fate of compounds generated following cholestane ring opening. If this paradigm-challenging hypothesis is true, the proposed studies should lead to the development of an entirely new approach for the medical management of CVD.

Link: https://projectreporter.nih.gov/project_info_description.cfm?aid=8181189

Request for Startups in the Rejuvenation Biotechnology Space, 2017 Edition

Some lines of rejuvenation research after the SENS model of damage repair, alongside a number of other useful compensatory technologies such as a select few gene therapies, have reached the point at which clinical development can make the leap to for-profit development in startups. There is a sizable amount of money out there on the sidelines waiting for this; investors of all stripes, from biotech veterans and new longevity-science-focused funds to angel communities. The message in this post is primarily intended for entrepreneurs and those out there in the scientific community with relevant work that is approaching the stage at which translational research and development can begin in earnest. We all know how hard it is to raise money for important, transformative research within the world of grants and philanthropic funding. If you have credible work and can put together a credible team, then look to venture funding sooner rather than later. That is my advice in the present environment.

I am interested in seeing the following types of technology emerge into for-profit development in the next few years, to join those like senescent cell clearance that are already well underway. The list is in no particular order of preference. If any of these cover your area of work and you have the ability to build a way to treat aging and its causes, then I want to hear from you. If you are working on anything else that is in the near future rejuvenation therapy list or the SENS portfolio, and is closer to realization than I expected it to be, then I want to hear from you. There is a growing community of investors out there with a considerable interest in seeing this field of research and development prosper.

Better Senescent Cell Assays

Cellular senescence is a cause of aging. Clearing these cells will turn back or slow the progress of many age-related conditions, and should extend healthy life spans at the same time. The current assays used to evaluate the presence of senescent cells in tissue are, shall we say, good enough for getting the job done in a laboratory setting when the goal is research and development. However, they are too manual, time-consuming, and costly for the near future in which near every adult will want to know the state of their cells before and after a clearance procedure, and in which senescent cell levels in specific tissues will become an important diagnostic tool for a range of age-related conditions. The existing assays are also poorly available to patients, where they exist at all in the current laboratory services market. Better, cheaper, faster assays are needed: ultimately, this should be something that is no more costly or challenging or restricted than is a blood sugar test kit that is sold over the counter.

Restoration of the Aged Thymus

There are numerous studies in mice demonstrating the ability to restore some fraction of lost immune function via transplantation or regeneration of the thymus, such as via foxn1 signaling or using forms of cell therapy and tissue engineering. A straight transplantation of a youthful thymus extends life in aged mice. These approaches work by enabling a higher rate of maturation of new T cells, which lessens some of the constraints that act to cause immunosenescence, the age-related decline in the immune system. This work is too promising not to be ushered rapidly towards the clinic, and some of the relevant lines of research are certainly close enough to make the leap.

Safe Ablation of Immune Cells Free from Side-Effects

Removing all or near-all circulating mature immune cells is an approach that has been used to cure multiple sclerosis, an autoimmune condition in which the immune system becomes misconfigured to attack crucial parts of the patient's cellular biochemistry. The immune system repopulates itself with fresh cells after such a comprehensive removal, but without any of the particular problems that produce autoimmunity. This should work equally well against any autoimmunity that doesn't have a strong genetic cause - or at least it would be very surprising to find an acquired autoimmunity that survived such a treatment. Similarly, many aspects of age-related immune dysfunction either involve autoimmunity or some other form of acquired imbalance and malfunction in immune cell populations. Removing all of the cells should help to turn back the clock to some degree, sweeping away that disarray. Unfortunately even the best of the present methods used to ablate immune cells so completely are essentially forms of chemotherapy: they have significant side-effects, and are probably unacceptably risky for older patients. To move ahead, methods of side-effect-free targeted destruction of all forms of immune cell are required: any such technology would immediately be applicable to autoimmunity and immunosenescence in the old.

Packaged and Reviewed Medical Tourism Services

We are on the verge of the clinical availability of worthwhile therapies that either compensate for or treat the causes of aging. This will happen outside the excessively regulated US medical system, in regions where only safety has to be demonstrated. BioViva and Sierra Sciences would like to offer follistatin gene therapies for example, and the first senolytic drugs to clear senescence cells are well categorized enough to be offered by any clinic just as soon as people put their minds to it. The availability of stem cell therapies developed in much the same way following the turn of the century. Despite that history, the medical tourism market is still very immature at the present time. There is a lack of organizations to provide informed reviews of clinics and procedures and to package the various needed portions of the product into one service: flight, stay, therapy, follow-up, and so on. When the flow of patients is small, as is the case for many medical conditions, it might make less sense to enter this market. The new therapies to treat the causes of aging will be beneficial to half of the population presently alive, including all of those presently in good health, however: an enormous market.

Gene Therapy with Reliable, Well-Established High Levels of Cell Coverage

As the initial BioViva data hints at, and as has been demonstrated in animal studies, the challenge for gene therapy is that without sufficient coverage of cells, and especially stem cell populations, the effects are small or transient. The first broadly useful gene therapies in the matter of aging are likely to be the myostatin and follistatin therapies that increase muscle mass, thereby slowing or somewhat compensating for the progression of sarcopenia. The first attempts in humans, either gene therapy or antibody blockade, are nowhere near as impressive as the results in mutant lineages in which all cells have the altered or missing genes, however. In this dawning CRISPR-powered era of gene therapies, there is first and foremost a great need for reliable, high levels of cell coverage. Any significant step towards solving this problem can be applied to the first classes of enhancement gene therapy, and thereby make them far more useful and valuable.

Small Molecule or Enzymatic Glucosepane Cross-Link Breaking

Cross-links in the extracellular matrix are a significant cause of aging, contributing to, for example, the chain of consequences that passes through arterial stiffening, hypertension, and finally cardiovascular disease and death. Also loss of skin elasticity, which most people seem to care about a lot more, somewhat irrationally. Comparatively little work is taking place to produce therapies that can break the dominant type of cross-link in humans, glucosepane, and most of that work is being funded by the SENS Research Foundation. Now that glucosepane has been efficiently synthesized, the door is open, however. Any group with knowledge of this area of biochemistry can put in practical work towards the production of good tissue models, antibodies suitable for glucosepane cross-link assays, and small molecule or enzymatic cross-link breakers. The SENS Research Foundation teams are not the only research groups out there who have expressed interest in this area in the past, and a little competition would be a welcome sign of progress.

Fear of a Grim Future as a Source of Opposition to Longevity Therapies

A great many people believe, despite all of the evidence to the contrary, that humanity is set upon a downward spiral into future far worse than the present. You will see this in any public discussion of rejuvenation therapies or efforts to slow aging: many participants couch their opposition to longevity therapies in terms of wishing to die before the world becomes worse. This sort of histrionic public display doesn't seem to be peculiar to our era. Dystopia has always held a greater fascination than utopia in literature, and heralds of the coming apocalypse have been around in one form or another for about as long as people have recorded their thoughts on the matter. Every story is the story of the Fall, as they say, in which the mythic past was better than the present, and in any given lifetime the combination of human psychology, degenerative aging, and the biochemistry of memory serves to make the past rosy with nostalgia in comparison to the uncertainties and pains of the present. Yet from an examination of the concrete data we are clearly not heading towards the abyss, or even a meaningful decline in the long term. Quality of life, longevity, and wealth has improved, steadily, for centuries. The pace is increasing, not decreasing. The future is golden and wondrous beyond easy measure. It is a fascinating and terrible aspect of the human condition that so many people reject this truth outright to find greater comfort in fear and self-sabotage.

The future looks grim? I would like to point out a few problems in the reasoning of the professional catastrophists who say that life won't be worth living and there's thus no point in extending it anyway. First, we need to take into account that the quality of human life has been improving, not worsening, throughout history. Granted, there still are things that are not optimal, but there used to be many more. Sure, it sucks that your pet-peeve politician has been appointed president of your country (any reference to recent historical events is entirely coincidental), and it sucks that poverty and famine haven't yet been entirely eradicated, but none of these implies that things will get worse. There's a limit to how long a president can be such, and poverty and famine are disappearing all over the world. It takes time for changes to take place, and the fact the world isn't perfect yet doesn't mean it will never be. Especially people who are still chronologically young should appreciate the fact that by the time they're 80 or 90, a long time will have passed, and the world will certainly have changed in the meanwhile. If we decided not to create rejuvenation because right now the world isn't as nice a place as it could be, in 60 years we may well end up as a bunch of sick, decrepit suckers with a foot in the grave, regretting our decision because in the meantime the world has become much better than we had expected.

Also, let's not forget that what we're talking about here is rejuvenation and that life extension is just a trivial consequence of it. Without rejuvenation, your health will eventually go below a critical threshold and the pathologies of old age will start to emerge. Even if the world did become a worse place to live in over the next few decades, frankly I fail to see how being sick and decrepit would make it any better. If death ever became preferable over life on this planet, painless suicide would be a much more humane and efficient option than going through the whole ordeal of old age. Additionally, if we're really so convinced that the world has no hope of being better in the future, then there's little point in making more babies. If we said we don't want to extend our lives because the world is and will forever be too horrible a place to live in, it would be rather contradictory - or even cruel, depending on how you want to see it - to bring more people into it. Either the world is broken beyond repair and we'd better not leave any progeny to live on it, or it can be fixed, in which case we may just as well stick around and start fixing it instead of complaining about how bad the world is.

Yes, we've got a problem with poverty, but it is not as bad as you might think. As a matter of fact, the number of people living below the threshold of absolute poverty has been plummeting over the last two centuries, going from somewhere in between 84% and 94% of the world population to something around 11% in 2013. Regardless of whether or not you think the world is going to be worth living in in the near future, odds are the present situation is better than your average Joe thinks it is. Maybe this is not your case - maybe you're well informed and you check your facts before jumping to conclusions - but you cannot possibly have not noticed the overall pessimism of people about issues like the ones above and the future in general. You don't believe me? Here's an example. In 2013, people in the UK were asked whether they thought extreme world poverty had increased, decreased, or stayed the same in the last 30 years. The correct answer was that, during that time, poverty had decreased faster than ever before in history. A whopping 55% thought that poverty had gone up. Only 12% got it right, and you should keep in mind that the interviewees were people holding university degrees. The US isn't doing any better, really: 66% thought extreme poverty had almost doubled over the course of the previous 20 years, while it had in fact almost halved. Why is this? Why is everyone prone to thinking we're doing so bad and that the future is grim, despite all the evidence indicating that we've improved a lot, we're doing far better than before, and we can expect to do even better?

We tend to see the details, but not the big picture. Most people understand the world by generalizing personal experiences which are very biased. In the media the "news-worthy" events exaggerate the unusual and put the focus on swift changes. Bad news sells. The media tend to magnify bad news over good news. We're more interested in bad news because of the potential danger they could represent for ourselves and our dear ones. Good news is generally less interesting, unless it touches us personally. Since the media live off selling news, they give out more bad news than good news. In that we have a flair for the dramatic. Personally, I think it's quite normal to feel uneasy and worried for the future whenever we hear bad news. Bad news puts us in a bad mood, and in a bad mood it is easier to see everything negatively. Further, when a lot of people all around you nod approvingly at stereotypes about poverty, tragedy, disgrace, all sort of catastrophes, supposed evilness of human race, etc, it is easy to think they're right just because they're many. Breaking from the crowd isn't easy, and a lot of people would rather just agree with the majority than having to go through the trouble of contradicting them. Further still, we tend to disqualify the positive. I wonder how many people, while reading this article, have thought something like: "Well, sure, poverty has diminished, but so what? It's still not zero." We need to appreciate any improvements we achieve.

In short, no, we're not doing badly. We're not doing perfectly, either, but we're doing pretty good. We have been improving for a long time now, and there's every reason to believe we will continue on this positive trend. If you want certainties, I doubt anyone can give you any; but there's sure cause for optimism. The best you can do is stick around with the rest of us and do your part, however small, to help make the world a better place.

Link: https://rejuvenaction.wordpress.com/answers-to-objections/objections-to-rejuvenation/why-live-longer-when-the-future-looks-so-grim/

An Example of Opposition to Living Longer

When technology provides the choice to live longer in good health, we should not forget that this is in fact a choice for the individual, no different from many other choices about medicine and life that already exist. It is civilized to respect those who decide that further time or improved health isn't their cup of tea, but as the debate over euthanasia illustrates, respect for self-determination really isn't something that comes naturally to those in power. It is one of the great failings of human nature. I point out this article as a catalog of the major categories of mistaken viewpoints and debates over extending human longevity from someone who has listened to the arguments and chosen the other path. Insofar as the end result is a personal choice to live longer or not, then that should be respected. The problems start when people work towards forcing that choice on others, by halting research or blocking availability of new technologies likely to extend life; fortunately we've seen much less of that sort of rhetoric now that scientists are closer to realizing ways to slow aging or produce rejuvenation in the clinic.

For my part, I'd say that the thing that turns people from life isn't time or cynicism, it is the burden of accumulated loss and pain: the friends no longer there, the debility and disease that encroaches year by year. That growing weight produces a great weariness, ultimately turning every simple act into a gray struggle. Even before that point it is unpleasant. This burden will be lifted through the application of better medical technology in the decades ahead; preventing the death of friends; removing the causes of pain and disability; restoring the resilience of youth in mind and body. Regardless of the plausible future, or the availability of specific therapies in any given year, it is still the case that individual choices in this matter should be respected.

At age 74, I have already experienced many of the indignities of aging and before very long will also confront the inevitability of death. Although neither prospect is particularly pleasant, I strongly believe in the normality and necessity of both. Claims that science will soon prevent aging and dramatically prolong life strike me as irresponsible hype and false hope. I am all for efforts to expand our healthspan, but see little value in prolonging our lifespan, and little possibility that we will soon discover a fountain of youth. My grandson, home from college for Christmas break, disagrees with what he regards as my sentimental and regressive attachment to the status quo. He is participating in stem cell and genetics research and believes that it is feasible and desirable to double the human lifespan and make aging just another curable disease. He has no qualms about this research and regards my doubts as technically naive and ethically unnecessary.

I say that the world is already terribly overpopulated and is rapidly becoming even more overpopulated. Malthusian dynamics ensure that providing a longer life for some must be purchased at the high cost of a more brutal life for the many - a life threatened by even more wars, migrations, famines, and epidemics. My grandson says that overpopulation is best solved by reducing birthrates. This has already been done with great success almost everywhere in the world except Africa and the Middle East. It will be a better, more mature, and healthier world if people live longer and have fewer diseases and fewer children. A longer lifespan will make people wiser, more future oriented, and less willing to take foolish risks in the present. This could lead to more rational decisions on how best to preserve our planet as a decent place to live.

I say that curing disease is the primary goal of medical science. But aging is not a disease - it is an entirely expectable wearing down, an expression of biological entropy that cannot be reversed. We should certainly target the diseases that occur in old age in an effort to extend the average human healthspan. Success will improve the well being of the elderly and have a small subsidiary effect on lifespan - e.g. more people living into their 80s, 90s, and 100s. But we should not expect that better treatment for diseases will allow people to live to biblical ages. My grandson says that it is far too early to tell whether aging in humans is more a reversible disease or an inescapable degenerative process. But since aging is caused by biochemical processes, it most likely can be prolonged by biochemical interventions. We can't decide the question based on values and reasoning - only by actually doing the aging research will we learn whether aging is preventable. And sure it may take many decades, but that's precisely why we have to allocate the resources now to get the project off to a fast start.

I say that only the rich will be able to afford new products that prevent aging and promote longevity. The resulting caste system based on lifespan will be even more unfair than our current divisions based on wealth and power. My grandson says that the distribution of benefits that will accrue from aging research is a political, economic, and ethical question, not a scientific one. Given human nature and existing institutional structures, the benefits will almost certainly be enjoyed in a markedly unequal and unfair fashion - greatly favoring the rich and powerful, with only a very slow trickle down to the population at large. This inequity has accompanied every previous technological advance in the long march of human progress and is not specifically disqualifying to progress in slowing aging and death.

I say that there is something arrogant and unseemly about tampering with anything so fundamental to life as aging and death. Their inevitability has always been an essential element governing the ebb and flow of all the species and all the individual organisms that have ever lived on our planet. Why assume that we have the right, or the need, to tamper with such a basic aspect of nature? My grandson says that scientific progress has always challenged conservative values based on a sentimental attachment to the past. He says that I would probably have worked hard to convince the first agriculturalists that they were breaking some sacred and natural code when they chose to settle down in one place rather than continue following the hunt. There is no inevitable, inexorable, over-riding, and natural law defining and governing one correct path of human destiny.

My grandson is much more optimistic than I that we will soon have the technical means to prolong youth and postpone death - and that we should use them. I am more accepting of the limits of life - eager to improve its quality, rather than expecting to extend its duration. My grandson trusts scientists to make scientific decisions. I believe that scientists have conflicts of interest that make them uniquely unqualified to judge the ethical implications of the scientific opportunities open to them. If scientists can do something, they will do it - fairly heedless of unintended consequences. My grandson has the optimism and enthusiasm of the young. I have the pessimism and caution of the old. In a final flourish, My grandson trumped my argument that aging and death are somehow natural to the evolutionary scheme of things with the paradox that evolution has also given us the power to control aging and death and that surely we are programmed to use it. He is probably right. I don't think our debate will be settled on ethical or theoretical grounds. History provides precious few examples of a society voluntarily rejecting the application of a powerful new technology - e.g. China burning its navy in the fifteenth century; Japan banning guns in the seventeenth. But both were closed societies whose conservative decisions were governed by internal political concerns; they were much less responsive than ours to economic and scientific competition and pressure. My guess is that scientists will be given the freedom and the funding to follow every possible path to the fountain of youth and to doubling the lifespan. Although our knowledge base is increasing exponentially, the more we learn about the body, the more we appreciate how difficult it is to translate basic science into clinical application. Our bodies are remarkably complex and carefully balanced machines. Scientists can tinker with them, but I suspect that the basic cycle of life and death will be very hard to change.

Link: http://www.huffingtonpost.com/allen-frances/a-debate-on-the-pros-and-_b_13843296.html

SENS Research Foundation is Hiring to Expand the Allotopic Expression Team

Here I'll point out one concrete example of the way in which the SENS Research Foundation puts our charitable donations to good use in rejuvenation research. You'll find many more in the yearly organizational reports. The in-house MitoSENS research team, focused on allotopic expression of mitochondrial genes to eliminate the contribution of mitochondrial damage to degenerative aging, has achieved considerable progress in the past two years. Allotopic expression is the process of placing copies of mitochondrial genes into the cell nucleus, altered in such as way as to allow the proteins produced from that genetic blueprint to find their way back to the mitochondria where they are needed. When mitochondrial genes become damaged, as happens over the course of aging, the backup source of proteins prevents this damage from starting a chain of events that causes lasting harm to tissues and organs.

Last year's MitoSENS crowdfunding initiative provided the funds needed for the SENS Research Foundation team to finish up the demonstration of allotopic expression of ATP6 and ATP8, the second and third mitochondrial genes for which this has been achieved. The SENS Research Foundation also used philanthropic donations to help fund the allotopic expression of the first such gene, ND4, some years ago. That research is now being carried forward to the clinic by Gensight Biologics, with sizable venture backing. To complete this defense against mitochondrial damage and aging, the same work must be completed for thirteen mitochondrial genes in total, and building upon recent success the SENS Research Foundation is expanding the MitoSENS team. If you happen to know a qualified researcher or biotechnologist, point them in this direction:

MitoSENS is Hiring

SENS Research Foundation (SRF) is hiring a Research Assistant for our research center located in Mountain View, CA. SRF is an exciting, cutting edge non-profit dedicated to transforming the way the world researches and treats age-related disease. We are seeking a research assistant in our MitoSENS group for a research project geared toward discovering a gene therapy approach to treating mitochondrial mutations; for more information see the project page. Qualified candidates will be local residents who have a BS or MS in the chemical/biological sciences and at least 2 years of work experience in either academia or industry. Duties will include mostly bench work in a small team-oriented environment. Candidates with experience in molecular cloning, tissue culture, protein analysis / biochemical assays are encouraged to apply. Experience working with mitochondria is a plus.

Engineering New Mitochondrial Genes to Restore Mitochondrial Function

Mitochondria provide energy for the cell by synthesizing energy in the form of high energy bonds. This energy synthesis occurs through a process called oxidative phosphorylation in which respiratory enzymes in mitochondria convert a molecule called adenosine diphosphate (ADP) into the energy currency of the cell, ATP. One interesting feature of mitochondria is that they contain their own DNA (mtDNA). As cells and mitochondria have co-evolved, most of this genetic information has been transferred to the nucleus, leaving only thirteen protein-encoding genes in the mtDNA. Housing these thirteen genes within the mitochondria themselves is precarious because the conditions required to synthesize ATP create reactive oxygen species. Over time, these toxic free-radical byproducts damage the mitochondrial genes in more and more cells, compromising respiratory chain function and hence energy production. The accumulation of mutations in mitochondrial DNA is implicated in the metabolic derangement of aging and in accelerating the course of the degenerative aging process as a whole. One need only examine clinical manifestations of mitochondrial genetic diseases to see the similarities they share with the maladies of aging. For example, mutations in the gene ND1 have been implicated in the development of Parkinson's disease, and Cytochrome B (CYB) mutations can cause muscle fatigue and exercise intolerance in young patients.

SENS Research Foundation's strategic approach to this problem is to engineer a way to let mitochondria keep producing energy normally, even after mitochondrial mutations have occurred. Although damage to mitochondrial DNA is inevitable so long as it is housed in the mitochondria, the harmful effects of mitochondrial mutations can be bypassed by engineering backup copies of the thirteen protein-encoding genes and housing the copies instead in the nucleus of the cell. These allotopic gene copies could continue to provide the necessary proteins even when mutations have compromised the mtDNA's ability to do so. Moreover, the nuclear gene copies would be better shielded from damaging toxins and better maintained by DNA repair machinery. Since the majority of mitochondrial proteins are naturally nuclear-encoded, the natural mechanism to deliver the allotopically-expressed genes to the mitochondria can be co-opted.

The SENS Research Foundation mitochondrial mutations team is moving forward on a method for targeting engineered nuclear-encoded genes (that could function as "backup copies" for cells with deletion mutations) to the mitochondria, and for furthermore optimizing the precision of this targeting. The "working copy" of the relocated mitochondrial gene in this method is equipped with two special sequences. One "untranslated" sequence is not turned into a protein itself, but helps protect the engineered protein during the import process. The other, called the mitochondrial targeting sequence, is a tag appended to the final protein following expression that allows it to be imported once expressed. Combining the two sequences allows the "backup copies" of genes to be turned into working copies in the cell nucleus; to have the "working copies" targeted to the surface of the mitochondria to be decoded and turned into protein. Even as it is still in the process of being decoded, the emerging protein is quickly directed to the surface of the mitochondria for import and incorporation into the electron transport chain (ETC), restoring mitochondrial function.

In 2013, the SENS Research Foundation mitochondrial mutations group created two new cell lines which are 100% null for two mitochondrially-encoded genes: ATP8 and CYB. Using these two new cell lines, this year the team was finally able to unleash their engineered ATP8 gene in cells whose mitochondria completely lack the ability to generate the corresponding proteins on their own, and announced the dramatic rescue of such "ATP8 null" cells using their protein targeting strategy. They anticipate that these results will deliver the proof-of-concept for the overall approach, which should then be applicable as a rescue platform for all thirteen mitochondrially-encoded proteins. Further work by the team aims to enable delivery of working instructions for building proteins that can keep the ETC intact and functioning in the event of age-related mutations of the original mitochondrial genes for these proteins. This method utilizes a "borrowed" structure already employed by mitochondria to take in RNA from the main body of the cell. The team has now achieved the critical first benchmark - i.e. delivering any RNA into the mitochondria - in this pioneering work using a convenient (but not naturally mitochondrially-expressed) RNA.

A Review of the Use of Primates in Aging Research

This review paper makes a good companion piece to another review on primates in aging research published last year. Perhaps the most well known primate studies of aging are the still ongoing and decades-long studies of calorie restriction in rhesus macaques, unlikely to be repeated given the cost and the debate over the quality of the resulting data and the underlying design of the studies. There are many other studies involving the use of various non-human primate species to study aging and age-related disease, however, some of which are just as interesting.

The choices made in the use of animals in aging research are a matter of economics: longer life spans and species closer to ours lead to studies that are slower and more costly, but the data is more likely to be useful and relevant. In practice the costs are too high, and thus most exploratory research into the biochemistry of aging starts out in very short-lived and evolutionarily distant species such as worms and flies. There is a high rate of failure for the results to translate into mammals, but even then the cost of progress is much lower that would be the case if carrying out that initial exploration in mice or other longer-lived mammals. All research involving primate studies has already passed through stages of exploration and validation in worms, flies, mice, and frequently other mammals as well; only the more established lines of research can justify the time and funding needed for further studies in primates.

Nonhuman primates share similar physiology and a close phylogenetic relationship to humans. The use of nonhuman primates in comparative experimental studies thus contributes to our knowledge about aging processes and translation of applications for improving health span in humans and other animals. With the growing development of antiaging strategies, it is expected that nonhuman primates will additionally be highly relevant for preclinical studies testing antiaging strategies. Correlates of average natural life span of an organism are highly complex, but body size in conjunction with metabolism, reproduction, immunity, and environmental stress, among other factors, is associated with average longevity such that larger animal species tend to live longer. Interestingly, human and nonhuman primates exhibit unusually longer average life spans that are nearly 4-fold higher than those of most other mammals relative to their body sizes. In addition, nonhuman primates exhibit similar key life span metrics as humans, such as higher infant mortality rate, followed by lower mortality during the juvenile stage and then an extended period of increasing age-related morbidity and mortality.

By far, the predominant nonhuman primate species utilized in biomedical research facilities as well as for studies on aging are rhesus macaques (Macaca mulatta) and cynomolgus macaques (Macaca fasicularis). Specifically, among the facilities with nonhuman primates in North America that were recently surveyed, 80% housed rhesus macaques of Indian or Chinese origin, followed closely by cynomolgus macaques housed in 73% of the facilities. Aspects of aging research studies that utilize macaques include neurobiology, anatomy, physiology, cognition, and behavior, as well as reproductive senescence, caloric restriction (CR), and immune senescence. The use of macaques in research appears to represent the best compromise between phylogenetic and physiologic relatedness to humans, cost efficiency, life span, resources, expertise in animal husbandry practices, and adaptability for translation of results to humans. To improve efficiency, accessibility, and applicability, however, increasing emphasis is being placed on purpose-bred animals and further advancing animal husbandry practices so that lower primates also may be included for relevant model development of research on aging.

Prosimians, or "premonkeys," are the most phylogenetically distant nonhuman primates from humans. Among the prosimians, grey mouse lemurs (Microcebus murinus) have been the most extensively studied for relating processes of aging in relation to humans. For example, the mouse lemur was the first nonhuman primate species to demonstrate a relationship between cerebral atrophy and cognitive decline with aging that simulated what was seen in aging humans. Neuroscience studies about memory, behavior, and psychomotor function have utilized both captive and wild mouse lemurs. The use of prosimians in research is more cost-efficient, but limitations include their smaller size that restricts specimen sampling; differences in metabolic, biochemical, and endocrine responses compared with humans; and a need for continued development in animal husbandry techniques to reduce stress-related behaviors of captive prosimians.

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5027759/

More Details to Show How the Clearance of Senescent Cells Impacts Vascular Aging

Accumulation of senescent cells is one of the root causes of aging. Now that the scientific community has the means to selectively remove these unwanted cells, such as via the use of senolytic drugs, and now that funding has picked up for this field, researchers are rapidly quantifying specific links to the pathology of age-related disease. For example, earlier this year researchers demonstrated that clearance of senescent cells produces significant benefits to vascular health, slowing or reversing many of the aspects of aging in blood vessels, such as calcification and growth of atherosclerotic plaque. This more recently published open access paper on the same topic adds more details to the picture:

Risk factors for ischemic heart disease include hypercholesterolemia, arterial stiffness, chronic inflammation, hypertension, metabolic syndrome, and aging. Importantly, these risk factors contribute to impaired endothelial function, which can contribute to arterial remodeling and accelerate atherosclerotic plaque formation and expansion. Recent work suggests senescent cell burden can be dramatically increased by chronological aging, and short-term treatment with 'senolytic' drugs alleviates several aging-related phenotypes. However, effects of long-term senescent cell clearance on vascular reactivity and structure with aging or chronic hypercholesterolemia remain unknown. To determine whether senolytic treatment with dasatinib and quercetin (D+Q) reduces senescent cell burden and improves vascular function in aged mice, we maintained C57BL/6J mice on standard chow for 24 months, and then initiated D+Q once monthly for 3 months.

Senolytic treatment resulted in significant reductions in senescent cell markers in the medial layer of aorta from aged and hypercholesterolemic mice, but not in intimal atherosclerotic plaques. While senolytic treatment significantly improved vasomotor function in both groups of mice, this was due to increases in nitric oxide bioavailability in aged mice and increases in sensitivity to NO donors in hypercholesterolemic mice. Senolytics tended to reduce aortic calcification and osteogenic signaling in aged mice, but both were significantly reduced by senolytic treatment in hypercholesterolemic mice. Intimal plaque fibrosis was not changed appreciably by chronic senolytic treatment. This is the first study to demonstrate that chronic clearance of senescent cells improves established vascular phenotypes associated with aging and chronic hypercholesterolemia, and may be a viable therapeutic intervention to reduce morbidity and mortality from cardiovascular diseases.

Link: http://onlinelibrary.wiley.com/doi/10.1111/acel.12458/full

Indirect Evidence for Misfolded Proteins that Accumulate in Muscle to Contribute to the Progression of Sarcopenia

One of the differences between old tissue and young tissue is an accumulation of misfolded proteins, normally soluable, into solid aggregates. The best known of these are the varieties of amyloid that are clearly associated with specific diseases and are present in significant amounts in patient tissues. These are far from the only proteins that accumulate in such a way, however, and there are many more types of misfolded or damaged proteins that do not form aggregates. Unfortunately the mapping of aggregates by tissue to specific consequences in the course of degenerative aging is far from complete. In the paper I'll point out today, the authors take an interesting path in their attempts to prove relevance of various aggregates to age-related loss of muscle mass and strength, the condition known as sarcopenia. I think that the approach is indirect enough to taken as a first filter that leads next to further study to evaluate how well it did, rather than being, on its own, any sort of confirming evidence for the participation of specific aggregates in the progression of sarcopenia. Even that is well before we get into questions of causation versus correlation. The challenge inherent in all investigations of aging is that it is a global phenomenon in the body; there are many correlations to be found between processes that in fact have little to do with one another, and spring from entirely separate sources. Still, the road to knowledge must start somewhere.

Loss of muscle mass and strength is one of the most visible signs of aging, and a large component of the frailty of old age. Once you start to lose strength you start to lose the ability to exercise and the benefits that brings, and things go downhill from there. There are a range of potential approaches to delay this process, of which calorie restriction and exercise are the most accessible and proven, and some near future therapies that could compensate for the loss, adding muscle without addressing the molecular damage of aging that produces sarcopenia as a downstream consequence. In the near future category are myostatin or follistatin gene therapies, and forms of temporary myostatin blockade such as the antibodies currently in clinical trials. Compensation is compensation and better than nothing, but what we really want to see is reversal via therapies that address the root causes of sarcopenia. At the present time there is little evidence as yet to definitively tie sarcopenia to specific root causes of aging, the categories of cell and tissue damage outlined in the SENS rejuvenation research programs. That is in comparison to the many studies linking sarcopenia to age-related changes that are most likely consequences of that damage, such as altered processing of leucine, changes in mitochondrial dynamics, and infiltration of fat into muscle tissue. Given that it is interesting to see people working towards links with protein aggregates, which are very definitely on the SENS list as a target for rejuvenation therapies, even if there is clearly a lot of work left to do to prove this connection via the methodology chosen here.

Proteins that accumulate with age in human skeletal-muscle aggregates contribute to declines in muscle mass and function in Caenorhabditis elegans

Age-associated muscle loss, or sarcopenia, results in functional decline that increases the risk for falls, disability, and mortality in older adults. This problem is clearly influenced by factors such as diet, physical activity, genetics, and comorbid health conditions. However, much less is known about the underlying etiology. Aging has detrimental effects on myofibers, satellite cells, and muscle protein synthesis. These effects may be due to dampened levels of growth factors needed for muscle growth and regeneration, or heightened levels of inflammation mediators, which can induce catabolism. Several age-associated diseases, particularly those involving neurodegeneration, feature the accumulation of protein aggregates in affected tissues. Interestingly, similar pathology is also seen for inclusion body myositis, an age-associated degenerative skeletal muscle disease, whose protein aggregates contain the amyloid β peptide characteristic of Alzheimer's disease. In diseased neurons and muscle fibers, aggregation is exacerbated by disruption of proteostasis systems responsible for repair or clearance of misfolded and damaged proteins. Muscle health is expected to be highly reliant on these processes since it reflects a lifetime of continuous mechanical and metabolic stress. However, a causal connection between protein aggregation and muscle aging or sarcopenia has yet to be established.

In the current investigation, we examined protein aggregation that accompanies muscle aging and assessed whether it might contribute to age-associated loss of muscle mass and function. This possibility was suggested by our recent studies which identified and quantified proteins in cardiac muscle aggregates that accrue with aging and hypertension in mice. Our work and that of others has also shown that protein aggregation accumulates with normal aging in the nematode Caenorhabditis elegans and in nematode models of protein-aggregation pathologies. The current study extends our investigation of protein aggregation to human muscle, with three objectives: 1) determine if aging is associated with increased protein aggregation in human skeletal muscle; 2) identify muscle-aggregate proteins that are differentially abundant with age; and 3) identify nematode orthologs of selected human aggregate proteins, and test their mechanistic involvement in protein aggregation and age-associated loss of muscle mass and function in C. elegans.

Previous proteomic comparisons of young and aged muscle for rodents and humans found 3-23% of soluble proteins altered in abundance with age. In the present analysis, 43% of the 515 proteins identified in muscle aggregates differed by at least a 1.5-fold in abundance between age groups, and 15% were significantly different, more than the 5% expected by chance. These results suggest that insoluble protein aggregates may be particularly susceptible to the effects of aging and could play a role in sarcopenia analogous to their role in the pathology of neurodegenerative diseases. This possibility was directly supported by disruptions of gene expression for C. elegans orthologs of human aggregate proteins: six of the seven tested knockdowns reduced protein aggregation and improved muscle-mass retention and resistance to amyloid-induced paralysis in aged nematodes.

By comparing aggregate amounts and compositions across human aging, and assessing functional impacts of aggregate-associated proteins through nematode studies, we were able to demonstrate that age-dependent accumulation of aggregates in muscle can underlie the loss of muscle mass and function that are commonly observed to accompany human aging. Skeletal muscle mass is expected to be influenced by relative rates of protein synthesis and degradation but the current study provides the first evidence that specific proteins are involved in the formation of insoluble protein aggregates that are toxic to muscle. Multiple proteins of diverse function were functionally implicated in protein aggregation, suggesting that the key causal parameter is the aggregate burden itself, rather than an upstream regulator of aggregation. Furthermore, since dampening production of aggregate proteins produced marked improvements in muscle mass and function, we propose that protein aggregation may provide attractive targets for therapeutic intervention in age-dependent sarcopenia. We conclude that protein aggregation is not unique to neurodegenerative disease and genetic myopathies, but is also characteristic of normal muscle aging and may contribute to muscle loss and functional decline with age.

Inhibition of PAI-1 as a Potential Treatment for Atherosclerosis

Researchers are investigating a drug candidate that inhibits plasminogen activator inhibitor-1 (PAI-1) as a potential treatment to slow the progression of atherosclerosis, in which fatty deposits build up in blood vessel walls. This leads to narrowing, structural failure of blood vessels, or blockage when the deposits grow unstable and rupture. The publicity materials in this case fail to join some of the dots to explain why this is interesting in the broader context; the evidence points to influence on cellular senescence as a possible mechanism for the effect here. Past research has shown that PAI-1 is involved in steering cells to a senescent state, and in the activities of cells while senescent. Further, senescent cells drive a sizable fraction of the growth and instability in the fatty plaques of atherosclerosis, and removing them slows the development of the condition. So we might take this sort of drug development research as further support for the benefits to be realized from bringing clearance of senescent cells to the clinic.

Approximately 2,200 Americans die each day from heart attacks, strokes and other cardiovascular diseases. The most common cause is blocked blood vessels that can no longer supply oxygen and nutrients to the heart and brain. A recent study has shown that a protein inhibitor drug prevents these blockages, and could be a new therapeutic approach to prevent heart attack, stroke and other diseases caused by blocked blood vessels. "Arteries are living hoses that narrow and enlarge in order to regulate blood flow to organs and muscles. Smooth muscle cells in the artery regulate blood flow by constricting and relaxing. However, when chronic inflammation occurs in a blood vessel - typically in response to diabetes, high cholesterol and cigarette smoking - the smooth muscle cells in the walls of arteries change their behavior. They gradually accumulate inside the artery and narrow the blood vessel. In the case of coronary arteries, which supply blood to heart muscle cells, this process produces blockages that can lead to a heart attack."

Plasminogen activator inhibitor-1, or PAI-1, is a naturally occurring protein within blood vessels that controls cell migration. With diseases such as diabetes and obesity, PAI-1 over-accumulates in blood vessels. This promotes blockage formation. This process occurs not only in arteries, but also in vein grafts in patients who have undergone coronary artery bypass graft surgery. The research team studied PAI-039, also known as tiplaxtinin, an investigational drug not yet used to treat humans. The researchers found that PAI-039 inhibited the migration of cultured human coronary artery smooth muscle cells, and prevented the development of blockages in arteries and bypass grafts in mice. "We found that PAI-039 decreased blockage formation by about 50 percent, which is a powerful effect in the models we used. In addition to reducing vascular blockages, inhibiting PAI-1 also produces a blood thinning effect that prevents the blood clots that trigger most heart attacks and strokes." If future studies are successful, PAI-039 or similar drugs could be used to prevent blockages in arteries and bypass grafts.

Link: http://medicine.missouri.edu/news/20161221-new-drug-could-help-prevent.php

Delivering Signal Molecules from Young Microglia to Aged Brain Tissue Enhances Removal of Amyloid

Microglia are a form of immune cell found in the central nervous system, responsible for a range of tasks including defense against pathogens and clearance of unwanted extracellular waste. Like all aspects of the immune system, their performance declines with age. Delivering young microglia to the aging brain has been proposed as a potential therapy by a number of research groups, and there has been some exploratory work in mice in recent years. Here researchers work in aged brain tissue sections rather than animal models, but show that introducing young microglia and the signals they produce enhances the removal of the amyloid-β deposits associated with Alzheimer's disease.

Alzheimer′s disease (AD) is the most prevalent neurodegenerative disorder and is pathologically defined by extracellular amyloid β (Aβ) deposition, neurofibrillary tangles, and neuroinflammation. Neuroimmune changes are tightly linked to the pathology of AD, as well as other neurodegenerative disorders. This link has been strengthened by recent discoveries of genes implicated in microglial function that are also risk factors for late onset AD. Interestingly, these newly identified risk factors may be functionally linked to microglial phagocytosis and Aβ clearance. Although microglia are well known for their phagocytic capacity and are found to surround amyloid plaques in mouse models of amyloidosis as well as in AD patients, their role in plaque clearance is still under debate.

One of the major limitations to study microglial contribution to amyloid plaque phagocytosis is the lack of suitable model systems. Major attempts to study microglial phagocytosis of Αβ come from studies using cultured microglial cells to which Aβ has been exogenously added. A key unresolved question is whether microglial dysfunction in AD is reversible and whether their phagocytic ability can be restored to limit amyloid accumulation. To this end, we developed a novel ex vivo model of amyloid plaque clearance by co-culturing young wild type (WT) brain slices together with brain slices from aged AD mice. We show that functional impairment of aged microglial cells in amyloid plaque-bearing tissue can be reversed through factors secreted by young microglia, resulting in increased amyloid plaque clearance and thus reduced amyloid plaque load. Our results suggest a role of microglia in reducing the amyloid burden and support development of therapeutic approaches modulating microglial activity.

Exposing old microglial cells to conditioned media of young microglia or addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) was sufficient to induce microglial proliferation and reduce amyloid plaque size. Our data suggest that microglial dysfunction in AD may be reversible and their phagocytic ability can be modulated to limit amyloid accumulation. This novel ex vivo model provides a valuable system for identification, screening, and testing of compounds aimed to therapeutically reinforce microglial phagocytosis.

Link: http://emboj.embopress.org/content/early/2016/12/20/embj.201694591

When Considering Aging, Don't Forget the Microbes

The environment surrounding our tissues and various complex systems such as organs incorporates a great deal of microbial life. We are surrounded by microbes, we have a whole cooperative ecosystem on our skins and another in our guts, and are constantly under attack by less friendly species. From the point of view of a great many classes of microbial life, we mammals are just another resource to be exploited as a basis for unfettered replication. Before the advent of modern medicine, life expectancy was largely determined by infectious disease and other environmental pathogens rather than the fundamental processes of aging. In the research paper linked below, the author makes a valid point, which is that we haven't really yet defeated the hostile microbes arrayed against us, just postponed their inevitable victory by decades for most individuals. When we consider aging, we should think about aging in the context of our vulnerability to the microbial world in addition to the failure of our component parts for other reasons.

This is really, I think, a type of argument for putting the age-related decline of the immune system at the top of the list of things to address when it comes to building rejuvenation therapies. I don't necessarily disagree, but it may be that our present state of knowledge makes it easier for us to join the dots between immunosenescence and inflammaging and all of the harm an age-damaged immune system causes, coupled with it being harder to quantify the specific contributions from other causes of aging. Now that senescent cell clearance is getting a whole lot more attention, for example, people are finding all sorts of links to specific age-related diseases and disease processes. When you can actually do something about a cause of aging, such as by clearing senescent cells, it becomes very much easier to find out how much harm they produce. Remove those cells and measure the outcome. Those experiments are ongoing at the moment, and a great deal is being learned. In the case of immune aging, there are several decades of good studies that compare various degrees of impairment of the aging immune system, and the role of inflammation in particular in aging is very well studied. The immune system plays many important roles beyond defense against pathogens, involved in everything from wound healing to destroying senescent and cancerous cells. All of these roles suffer due to the growing disarray in an aged immune system.

But of course, absent increasingly comprehensive medical support, the microbes will get you in the end. The cell and tissue damage of aging produces frailty throughout all of our biological systems, and it isn't just the immune system that becomes less resilient. The immune response becomes less able to defend against attackers, and at the same time it takes less of a disruption due to infection to produce a fatal decline in already precarious vital organ functions. A very great many old people are tipped over the edge by infections that they wouldn't have even noticed a few decades earlier in life. There is still a great deal of work to do in the control of infectious disease, a goal that will probably be more easily achieved by augmenting our natural immune systems with more efficient molecular nanotechnology than by sterilizing the world, but consider how rare fatal infections are nowadays for younger adults when compared to the old. The biggest gains in the near future will come through rejuvenation of the immune system: destroying and then recreating immune cells to remove misconfiguration; regenerating the thymus to increase the supply of new immune cells; supplying new pools of pristine bone marrow stem cells responsible for creating immune cells; and so on.

Classifying Aging As a Disease: The Role of Microbes

Recent publications have proposed that aging should be classified as a disease. The goal of this manuscript is not to dispute these claims, but rather to suggest that when classifying aging as a disease, it is important to include the contribution of microbes. As recently as ~115 years ago, more than half of all deaths were caused by infectious diseases. Since then, the establishment of public health departments that focused on improved sanitation and hygiene, and the introduction of antibiotics and vaccines allowed for a dramatic decrease in infectious disease-related mortality. In 2010, the death rate for infectious diseases was reduced to 3%. Simultaneously, as infectious disease-related mortality rates have decreased, global life expectancy has increased from ~30 to ~70 years.

Because death rates due to infectious diseases have been reduced to very low levels, we've forgotten about the adverse effects of microbes on our existence. The fact is, we live in a microbial world. Even at a young chronological age, microbes find their way into the blood and tissues. Circulating microbial DNA is found in young, healthy adults. Interestingly, levels of circulating bacterial DNA are not homogeneous: some subjects had 3-fold or more circulating bacterial DNA when compared with others. Moreover, various bacterial species are found in skeletal muscle, heart, liver, adipose tissue, and in the brains of young mice. With the passage of time, the barriers responsible for keeping microbes out of us weaken. For example, tight junctions (TJs) connect epithelial cells, thereby minimizing the space in between the cells, and minimizing the ability of microbes to translocate into the blood. Bacteria and viruses have evolved mechanisms to impair TJ assembly. Whether caused by pathogenic microbes or because of defects in host gene expression, levels of many of these tight junction proteins are decreased in old, when compared with young. Furthermore, although the immune system should protect us against an increase in microbial burden, however, many aspects of the immune response are decreased, whereas others are increased, thereby resulting in dysregulation. This phenotype is known as immunosenescence.

The impact of decreased barrier function and immunosenescence would be expected to lead to an increase in circulating microbes in old, when compared with young. Although circulating levels of bacterial DNA have yet to be reported in older adults, plasma levels of lipopolysaccharide (LPS), which is found in the outer membrane of gram-negative bacteria, and levels of the receptors that bind to LPS (TLR4) and to bacterial flagellin (TLR5), are elevated in older adults, when compared with young. In line with this, the incidence of bloodstream infections with LPS-containing Escherichia coli is increased by more than 10-fold in adults older than 74, when compared with subjects younger than 50 years. Similarly, the incidence of bloodstream infections with gram-positive bacteria is elevated by more than 8-17 fold in older adults.

What are the consequences of an age-related increase in microbial burden? Microbes and/or microbial products are causatively involved in multiple theories of aging, including insulin resistance, oxidative stress, inflammation, and telomere shortening. In support of this, LPS injection into young, healthy subjects causes insulin resistance. Oxidative stress is increased in response to the binding of LPS and bacterial flagellin to their respective receptors. Levels of the pro-inflammatory cytokines IL-6 and TNF-α are increased when LPS binds to TLR4. Telomere shortening occurs at a faster rate in the presence of cytomegalovirus (CMV) infection. Interestingly, the prevalence of CMV infection increases from ~20% in adults younger than 50 years, to ~40% in 50-70 year olds, to 100% in adults older than 70. Collectively, these data support a causative role for microbial burden on mechanisms that have been commonly hypothesized to drive the aging process. Microbial burden is also involved in mechanisms related to age-related disease, including cardiovascular disease (CVD), Alzheimer's disease, cancer, stroke, and diabetes. In support of this, approximately 10-fold more circulating bacterial DNA is found in CVD patients, when compared with healthy controls.

If we are fortunate to avoid the common age-related diseases and live to achieve centenarian status, infectious disease as a major cause of death arises again. In Japan, more than 40% of all centenarian deaths are due to infectious diseases, including pneumonia. Similarly, in a larger study of ~36,000 centenarians from the UK, other than "old age," the leading cause of death was pneumonia. In short, over the past 115+ years, we haven't eliminated the adverse effects of microbes on our health, we've merely delayed them! As an argument against the role of microbes on causing many aspects of aging and age-related disease, it is important to note that host aging does indeed occur in their absence. Although lifespan in microbe-free mice is increased by 20-50%, these animals are not immortal. Nonetheless, as presented here, microbes are involved in mechanisms related to aging and age-related disease, and accordingly, I posit that any classification of aging as a disease should include the contribution of microbes.

A View of Scaffolds in Tissue Engineering

In this short interview, the main topic of discussion is the use of nanoscale scaffolding materials in tissue engineering. They act as a temporary substitute for the extracellular matrix that normally supports cells, allowing cells to survive and move in order to form new tissue. Ultimately the cells replace the scaffold with new extracellular matrix structures, and the end result is regrowth of tissue where that regeneration would not normally have occurred.

For tissue engineering and repair, we've been focusing lately on skeletal muscle. There's really a medical need for platforms or scaffolds for muscle fiber regeneration, since after injury the body's abilities to repair skeletal muscle are really quite limited. Skeletal muscle makes up a large part of the human body - 40 to 50 percent by weight. And when damage occurs to skeletal muscle on a small scale, we've seen that skeletal muscle possesses innate repair mechanisms. Through these mechanisms, a new fiber can grow, for example, essentially repairing or replacing the damaged one. But above a critical threshold of damage to skeletal muscle, our bodies no longer employ those effective repair mechanisms. Instead, the body forms scar tissue at the wound site - and then you've essentially lost control of that muscle function. You can't get it back. Surgically, you could graft in skeletal muscle. But that depends on the availability of donor tissue. So we know that the body can repair skeletal muscle. It just doesn't do so beyond a certain threshold of damage.

Natural skeletal muscle is surrounded by a complex extracellular matrix that supports muscle fibers as they form and grow in the body. What we would like to do in this field, which many researchers are working on, is to create an artificial extracellular matrix into which we could introduce a progenitor type of cell - like stem cells or muscle progenitor cells - and then provide them with the proper signals to differentiate into muscle fibers. We believe that scaffold and signals are what is needed to grow new muscle fibers, which you could then transplant to the site of damage. In general, with designing scaffolds for cell growth, the material we work with really depends on the type of cell we'd like to introduce into the scaffold to proliferate. For bone tissue regeneration, which we've worked on in the past, we created a scaffold made of chitosan - a complex polysaccharide, essentially long chains of sugar-like molecules - combined with other materials to create a calcified scaffold. For skeletal muscle, we and other researchers work with a variety of anisotropic materials.

Anisotropic materials have physical properties that differ based on direction or orientation. They form the basis of the scaffolds and are usually complex polymer materials. The innate "directionality" of anisotropic materials helps the progenitor cells grow into three-dimensional forms like a myotube, which is a precursor to a muscle fiber. But there are structural challenges to overcome. The scaffold must be micropatterned to promote cell migration, growth and proliferation in the right direction. This involves nanoscale design details, and some polymers are better for this than others. The production of highly aligned nanofibers in a large area remains a great challenge. We have developed several methods to produce nanofibers made of natural polymers with a high degree of alignment and uniformity over large areas. In addition, we often coat the scaffold with biomolecules that help the cells stick to the scaffold and provide them with the right signals to grow and differentiate: adhesion proteins, growth factors and transcription factors that deliver specific messages to cells depending on their structure and location in the scaffold. By changing what we make the scaffolds out of, the protein messages we coat them with or the nanopore structures within the scaffolds, we can reveal many different properties of cells. We can also test the types of external signals, be it a structural feature of the scaffold or a protein message, that can promote or inhibit cell growth.

Link: http://www.washington.edu/news/2016/12/19/uw-researcher-pursues-synthetic-scaffolds-for-muscle-regeneration/

Blind Mole-Rat Longevity a Side-Effect of Resistance to a Low Oxygen Environment

It has for a while been the consensus theory that usual aspects of naked mole-rat biology, such as its extreme cancer resistance and exceptional longevity for its size, are at least in part the outcome of evolving to thrive in the low-oxygen environment found in underground burrows. In most mammals, lack of oxygen followed by its return is quite damaging, but much less so in naked mole-rats. The nature of the mechanisms linking resistance to low-oxygen environments with longevity, and their relative importance when compared to one another, is still up for debate, however. A number of other similar burrowing rodent species are also long-lived and cancer resistant. Here, researchers survey the biochemistry of the blind mole-rat:

The blind mole rat of the genus Nannospalax (hereafter, Spalax) is a subterranean, hypoxia tolerant rodent, evolutionarily related to murines. The last common ancestor of Spalax, mouse, and rat lived ~46 million years ago. Despite the tight evolutionary relatedness of Spalax and murines, they exhibit profound differences in lifespan, propensity to cancer diseases. Although a very common cause of death in rats and mice is cancer, Spalax resists experimentally induced carcinogenesis in vivo and does not develop spontaneous cancer. While both rat and Spalax have comparable body weights, their maximum lifespan is ~4 years and ~20 years, respectively. The naked mole rat (Heterocephalus glaber), another hypoxia-tolerant subterranean species of the Bathyergidae family, separated by ~85 million years of evolution from Spalax, is also long-lived, and was reported to be less sensitive to spontaneous cancers.

Molecular adaptations to subterranean life and longevity where suggested for this species, in a brain transcriptome study. Noteworthy, we have proved that both Spalax and naked mole rat's normal fibroblast secrete substance/s interacting with cancer cells from different species, including a wide variety of human cancer cells, ultimately leading to the death of the cancer cells. In addition, sequence similarities between distantly related hypoxia-tolerant species (diving- and subterranean- mammals) were found in the protein sequence of p53, a master regulator of the DNA damage response (DDR). These studies indicate that adaptations to hypoxia include changes in the DDR that may be linked to cancer resistance, and longevity traits.

Under laboratory conditions, Spalax survives ~3% O2 for up to 14 hours, whereas rat survives such conditions for only ~2-3 hours. Oxygen levels measured in Spalax's natural underground burrows vary between ~21% and 7%, depending on seasonal and ecological conditions. In its natural habitat, Spalax is exposed to acute and transient hypoxia, such as: (i) long-term periods of hypoxia during seasonal rainfalls, which reduce soil permeability to oxygen, and simultaneously reduce the total space available to the animal; and (ii) short-term periods of hypoxia during extensive digging activity, when burrows are clogged by soil pushed to the rear by the animal, forcing it to perform an energy-consuming activity in a small burrow fragment with a limited amount of oxygen. Hence, in its natural habitat, Spalax faces acute cyclical changes in oxygen levels. By the term "acute hypoxia" we refer to short- or long- term hypoxia for a limited period, followed by reoxygenation, which is in contrast to "mild-chronic hypoxia" characterizing habitats, such as high altitudes.

Many of the genes that showed higher transcript abundance in Spalax are involved in DNA repair and metabolic pathways that, in other species, were shown to be downregulated under hypoxia, yet are required for overcoming replication- and oxidative-stress during the subsequent reoxygenation. We suggest that these differentially expressed genes may prevent the accumulation of DNA damage in mitotic and post-mitotic cells and defective resumption of replication in mitotic cells, thus maintaining genome integrity as an adaptation to acute hypoxia-reoxygenation cycles.

Link: https://dx.doi.org/10.1038/srep38624

Piperlongumine as a Senolytic Drug Candidate with Fewer Side-Effects

Today's open access research paper outlines the discovery of yet another new candidate drug for the selective destruction of senescent cells. This is an increasingly popular research topic nowadays. Senescent cells perform a variety of functions, but on the whole they are bad news. Cells become senescent in response to stresses or reaching the Hayflick limit to replication. They cease further division and start to generate a potent mix of signals, the senescence-associated secretory phenotype or SASP, that can provoke inflammation, disarray the surrounding extracellular matrix structures, and change behavior of nearby cells for the worse. Then they destroy themselves, or are destroyed by the immune system - for the most part at least. This is helpful in wound healing, and in small doses helps to reduce cancer incidence by removing those cells most at risk of becoming cancerous. Unfortunately a growing number of these cells linger without being destroyed, more with every passing year, and their presence eventually causes significant dysfunction. That in turn produces age-related disease, frailty, and eventually death. Senescent cells are not the only root cause of aging, but they provide a significant contribution to the downward spiral of health and wellbeing, and even only their own would eventually produce death by aging.

The beneficial aspects of senescent cells seem to require only a transient presence, so the most direct approach to the problem presented by these cells is to destroy them every so often. Build a targeted therapy capable of sweeping senenscent cells from tissues, and make it efficient enough to keep the count of such cells low. That is the way to prevent senescent cells form contributing to age-related disease. Working in mice, researchers have produced results such as functional rejuvenation in aged lungs and extended life span through the targeted destruction of senescent cells. Since perhaps only a few percent of the cells in old tissue are senescent, this targeted destruction can be accomplished with few side-effects beyond those generated by off-target effects of the medication itself. There are a range of potential ways to destroy senescent cells while leaving other cells intact: the last twenty years of work on the basis for targeted cell destruction in the cancer research community has produced many useful tools. These include the programmable gene therapy approach adopted by Oisin Biotechnologies, immunotherapies of the sort under development by SIWA Therapeutics, and apoptosis inducing senolytic drugs of the sort championed by UNITY Biotechnology. This last category has a particularly close tie to the cancer research community, and in fact the senolytic drugs we know the most about, such navitoclax, also known as ABT-263, are well-categorized precisely because they have been trialed as cancer therapies in past years.

Senescent cells are in a sense primed for apoptosis, a process of programmed cell death. They need less of a nudge to finish that process than normal cells, and so a large number of the varied drugs that can induce apoptosis to some degree might have a future as plausible senolytic therapies. Cancer research groups have libraries of such compounds, many of which might turn out to be far more useful as senolytics than they ever were as cancer treatments. So we should expect to see a growing number of such drug candidates in the years ahead as various research groups and companies shake their archives to see what falls out. So far the first set of drugs, including navitoclax, are largely based on inhibition of bcl-2 family proteins, and have a range of unpleasant side effects. They are in effect chemotherapeutics, but it is likely that their use as senolytics will require lower doses than were used in cancer trials, but that remains to be established, however. The possible side-effects of repurposed chemotherapy drugs are one good reason to favor an approach like that taken by Oisin Biotechnologies, which is a treatment that has next to no side-effects, or at the very least to put more effort into finding drug candidates with alternative mechanisms and far fewer side-effects, as is the case in the research here.

Discovery of piperlongumine as a potential novel lead for the development of senolytic agents

Cellular senescence, an essentially irreversible arrest of cell proliferation, can be triggered when cells experience a potential risk for malignant transformation due to the activation of oncogenes and/or DNA damage. While eliminating aged or damaged cells by inducing senescence is an effective barrier to tumorigenesis, the accumulation of senescent cells (SCs) over time compromises normal tissue function and contributes to aging and the development of age-associated diseases. Often, SCs secrete a broad spectrum of pro-inflammatory cytokines, chemokines, growth factors, and extracellular matrix proteases, a feature collectively termed the senescence-associated secretory phenotype. These factors degrade the local tissue environment and induce inflammation in various tissues and organs if SCs are not effectively cleared by the immune system.

Studies have shown that the genetic clearance of senescent cells extends the lifespan of mice and delays the onset of several age-associated diseases in both progeroid and naturally-aged mice. These findings support the hypothesis that SCs play a causative role in aging and age-associated diseases and, importantly, highlight the tremendous therapeutic potential of pharmacologically targeting SCs. Consistent with these findings, we have shown that ABT-263 (navitoclax), an inhibitor of the antiapoptotic Bcl-2 family proteins, acts as a potent senolytic agent to deplete SCs in vivo and functionally rejuvenates hematopoietic stem cells in both sublethally irradiated and naturally-aged mice. Complementary studies from other labs have confirmed that the Bcl-2 protein family is a promising molecular target for the development of senolytic drugs. These studies further establish the concept that the pharmacological depletion of SCs is a promising, novel approach for treating age-associated diseases. ABT-263 was identified by screening a small library of structurally diverse, rationally-selected small molecules that target pathways predicted to be important for SC survival. By titrating their cytotoxicity against normal human WI-38 fibroblasts and ionizing radiation (IR)-induced senescent WI-38 fibroblasts, this targeted screen also identified the promising senolytic agent piperlongumine (PL); PL is a natural product isolated from a variety of species in the genus Piper. Here, we report the characterization of PL as a potential novel lead for the development of senolytic agents.

Selective depletion of SCs is a potentially novel anti-aging strategy that may prevent cancer and various human diseases associated with aging and rejuvenate the body to live a longer, healthier life. As such, several senolytic agents, including ABT-263, have been identified recently, demonstrating the feasibility of pharmacologically targeting SCs. However, ABT-263 induces thrombocytopenia, and it remains to be determined whether ABT-263 can be used to safely treat age-related diseases, since individuals may require long-term treatment with a senolytic drug. Thus, it is necessary to identify a safer senolytic drug. In the present study, we evaluated PL as a novel senolytic agent. PL induced caspase-mediated apoptosis in SCs and effectively killed SCs induced by IR, replicative exhaustion, or ectopic expression of the oncogene Ras. Unlike ABT-263, the precise mechanism of action by which PL induces SC apoptosis remains unclear. PL modulates the activity of many cell signaling and survival pathways in cancer cells, and a number of studies have investigated the mechanism of action by which PL induces apoptosis in these cells. Data from these studies may be translatable to PL-induced SC apoptosis because SCs and cancer cells share some common pro-survival pathways. In addition, mass spectrometry-based proteomic approaches using probes derived from PL could be used to identify direct molecular targets of PL in SCs. In this regard, novel anti-senescent protein targets and mechanisms of action could be identified, making it possible to develop promising novel classes of senolytic agents. Importantly, PL appears to be safe; the maximum tolerated dose in mice is very high, and it maintains high bioavailability after oral administration. Furthermore, our initial structural modifications to PL demonstrate that we can develop PL analogs with increased potency and selectivity toward SCs, supporting the use of PL as a lead for further drug discovery and development.

Immune Restoration Results from Placing a Young Thymus into an Aged Mouse

Some of the issues causing progressive age-related failure of immune function result from the low rate of replacement of T cells in adults. T cells are created in the bone marrow but mature in the thymus, an organ that atrophies early in life in a process known as thymic involution. It then declines more slowly thereafter across the course of a life span. The level of activity in the thymus limits the rate at which new T cells arrive, and this in turn effectively puts a limit on the number of such cells supported by the body, and determines the rate of turnover in that population. As we age and are exposed to persistent pathogens, especially cytomegalovirus, ever more of the T cell population becomes specialized in ways that remove the ability to deal with new threats. A flood of new immune cells would help to restore the balance, and in recent years researchers have demonstrated that transplanting a young and active thymus into an old mouse does in fact restore measures of immune function, and extends life span as well. This is an indication that the research community should put more effort into regeneration and tissue engineering of the thymus as a way to partially reverse the age-related loss of immune function and the frailty that follows that loss.

The peripheral T cell compartment of aged individuals is characterized by great modifications, including a higher frequency of regulatory T cells (Treg). A tight balance between regulatory and conventional (Tconv) T cell subsets in the peripheral compartment, maintained stable throughout most of lifetime, is essential for preserving self-tolerance along with efficient immune responses. An excess of Treg cells, described for aged individuals, may critically contribute to their reported immunodeficiency. The relative contribution of alterations in thymic exportation versus changes in the homeostasis of the peripheral compartment affecting the Treg/Tconv lymphocytes balance is not yet clearly established, however. In this work, we investigated if quantitative changes in thymus emigration may alter the Treg/Tconv homeostasis regardless of the aging status of the peripheral compartment. We used two different protocols to modify the rate of thymus emigration: thymectomy of adult young (4-6 weeks old) mice and grafting of young thymus onto aged (18 months old) hosts. Alterations in Treg and Tconv peripheral frequencies following these protocols were investigated after 30 days.

Our results show that peripheral T cell homeostasis is promptly disturbed in the absence of the thymus. This disturbance was characterized by a preferential persistence of Treg cells that occurs independently of the age of either the T cells or the peripheral environment. The excess of Treg cells in aged mice is also very rapidly corrected by the grafting of a young functional thymus, supporting the hypothesis that thymus newly emigrated T cell populations, harboring an adequate physiological proportion of Treg/Tconv lymphocytes, are essential to compensate for an excess of peripheral Treg cell expansion or survival. It is also interesting to observe that the aged T cell precursors are fully able to colonize and differentiate in the young grafted thymus. These results suggest that the continuous output of the young grafted thymus, which is numerically much superior to the small number of cells emigrating from the aged host thymus, may contribute to normalize the peripheral proportions of Treg/Tconv cells. The aged peripheral compartment does not interfere with this homeostasis.

Our results, thus, highlight the importance of the thymus as a permanent source of emigrating populations of recently differentiated lymphocytes harboring an adequate, physiological proportion of Treg/Tconv lymphocytes, essential to keep the peripheral Treg cell balance, regardless of the aging status of the peripheral compartment. The immunosenescence associated with aging, in which an excess of Treg cells may impair the immune response to infections and tumors, highlights the relevance of understanding the peripheral Treg cell homeostasis for the development of adequate clinical strategies.

Link: http://onlinelibrary.wiley.com/doi/10.1002/iid3.132/full

Towards Regeneration of Dental Pulp in Damaged Teeth

Regeneration rather than removal of damaged teeth lies somewhere in the near future, through some combination of tissue engineering of new teeth versus therapies that spur in situ regeneration of tooth structures. Researchers have been making progress towards this goal for some years, and there are any number of promising studies in laboratory animals reported in the literature. Here is one example of the sort of work presently taking place:

When a tooth is damaged, either by severe decay or trauma, the living tissues that comprise the sensitive inner dental pulp become exposed and vulnerable to harmful bacteria. Once infection takes hold, few treatment options - primarily root canals or tooth extraction - are available to alleviate the painful symptoms. Researchers now show that using a collagen-based biomaterial to deliver stem cells inside damaged teeth can regenerate dental pulp-like tissues in animal model experiments. "Endodontic treatment, such as a root canal, essentially kills a once living tooth. It dries out over time, becomes brittle and can crack, and eventually might have to be replaced with a prosthesis. Our findings validate the potential of an alternative approach to endodontic treatment, with the goal of regenerating a damaged tooth so that it remains living and functions like any other normal tooth."

Researchers examined the safety and efficacy of gelatin methacrylate (GelMA) - a low-cost hydrogel derived from naturally occurring collagen - as a scaffold to support the growth of new dental pulp tissue. Using GelMA, the team encapsulated a mix of human dental pulp stem cells - obtained from extracted wisdom teeth - and endothelial cells, which accelerate cell growth. This mix was delivered into isolated, previously damaged human tooth roots, which were extracted from patients as part of unrelated clinical treatment and sterilized of remaining living tissue. The roots were then implanted and allowed to grow in a rodent animal model for up to eight weeks. The researchers observed pulp-like tissue inside the once empty tooth roots after two weeks. Increased cell growth and the formation of blood vessels occurred after four weeks. At the eight-week mark, pulp-like tissue filled the entire dental pulp space, complete with highly organized blood vessels populated with red blood cells. The team also observed the formation of cellular extensions and strong adhesion into dentin - the hard, bony tissue that forms the bulk of a tooth. The team saw no inflammation at the site of implantation, and found no inflammatory cells inside implanted tooth roots, which verified the biocompatibility of GelMA.

Control experiments, which involved empty tooth roots or tooth roots with only GelMA and no encapsulated cells, showed significantly less growth, unorganized blood vessel formation, and poor or nonexistent dentin attachment. The results support GelMA-encapsulated human dental stem cells and endothelial cells as part of a promising strategy to restore normal tooth function. "A significant amount of work remains to be done, but if we can extend and validate our findings in additional experimental models, this approach could become a clinically relevant therapy in the future."

Link: https://www.eurekalert.org/pub_releases/2016-12/tuhs-nsc121916.php

Presenting Mitochondrial Rejuvenation at a Google Tech Talk

As the clock ticks on this year's SENS rejuvenation research fundraiser - less than two weeks to go now, and plenty left in the matching fund for new donations - it is good to be reminded of the progress that the SENS Research Foundation has accomplished with the charitable funding of recent years. With that in mind, today I'll point you to a recent Google Tech Talk that provides a layperson's introduction to one of the projects that our community has funded, fixing the problem of mitochondrial damage in aging. The point of the SENS (Strategies for Engineered Negligible Senescence) research programs is to accelerate progress towards specific forms of therapy that can bring aging under medical control. To the extent that degenerative aging and age-related disease is caused at root by a few classes of molecular damage, it follows that control of aging - halting and reversing the decline - can be achieved by periodically repairing the damage. The more of it that is repaired, the better the outcome. If all of the fundamental forms of damage could be kept below the levels present in a typical 30 year old, sustained there by a package of treatments undertaken every few years, then individuals would no longer age, no longer suffer disease and frailty, and no longer suffer increased mortality with the passage of time. That, at least, is the goal. It will become clear as the research and development progresses to what degree edge cases and unforeseen issues exist.

One of the forms of damage that causes aging occurs to mitochondrial DNA. Every cell has a swarm of hundreds of mitochondria, the evolved descendants of symbiotic bacteria that over time have become fully integrated as a component part of our cells. They still divide and multiply like bacteria, and have a little of their original DNA left, completely separate from the DNA of the cell nucleus. Mitochondrial DNA encodes a few vital pieces of molecular machinery, such as portions of the electron transport chain that is used in the process of producing chemical energy store molecules to power the cell. Mitochondria are power plants, effectively, among the many other essential tasks they have adopted over the course of evolution. Unfortunately mitochondrial DNA is more vulnerable to damage and its repair mechanisms are less capable when compared to the DNA of the cell nucleus. Damage accumulates. Equally unfortunately, some forms of damage, such as large deletions that hamper the electron transport chain by denying it necessary parts, produce mitochondria that are both dysfunctional and better able to replicate and resist destruction by cellular quality control systems. A minority of cells become overtaken by these broken mitochondria as we age, and themselves become broken, generating and exporting harmful reactive molecules into our tissues. This causes enough further damage to be a significant cause of age-related disease.

The SENS Research Foundation proposes the use of gene therapy to copy these vulnerable genes into the cell nucleus, altered in order to enable the proteins produced to find their way back to the mitochondria. This produces a backup source of the proteins, and thereby eliminates the contribution of mitochondrial DNA damage to aging. This is hard work: there are thirteen genes to copy, and every one of them requires its own complicated solution to the challenge of getting the proteins back to the mitochondria. Equally, most of these genes are associated with inherited disorders, in which a patient has a damaged copy in all mitochondria. So it is possible to produce a proof of principle for a single gene and do some good at the same time. Nearly a decade ago, the SENS Research Foundation started to support work on one of these genes, NH4, that enabled a treatment for Leber's hereditary optic neuropathy (LHON). That area of research was very poorly funded at the time, and as a direct result of that SENS Research Foundation support a well-funded company is now bringing a therapy to the clinic, and looking at doing the same for other related genes. This year, the SENS Research Foundation in-house team demonstrated the same outcome for two more mitochondrial genes, ATP6 and ATP8. That work was funded by donations from people like you and I, and the researcher leading the effort recently gave a presentation in the Google Tech Talk series:

Google TechTalk: Rejuvenating the Mitochondria

"Engineering Approaches to Combating the Diseases and Disabilities of Aging: Rejuvenating the Mitochondria." This is a talk for a general audience on the work of the SENS Research Foundation to fight age related diseases with a focus on repairing the damage that accumulates as we age. The SENS Research Foundation recently published a paper on their research into repairing cells that lack two of the thirteen essential mitochondrial proteins. The SRF scientists were able to reengineer the two mitochondrial genes and move them to the nucleus of the cell, restoring the missing proteins. This work is significant for both its impact on treating age related diseases but also on childhood diseases resulting from a lack of certain mitochondrial proteins.

Lowering Cholesterol Levels to a Large Degree Further Reduces Cardiovascular Risk

Researchers here provide evidence to show that lowering blood cholesterol levels to a large degree via new treatments is more beneficial for patients than the more modest targets for lower cholesterol, achieved via lifestyle choices and drugs such as statins, previously set by the research community:

Reducing our cholesterol levels to those of a new-born baby significantly lowers the risk of cardiovascular disease, according to new research. Although previous studies have suggested lowering cholesterol levels may be associated with a lower risk of heart attack, recent evidence has questioned whether very low levels are beneficial. In the latest study, researchers analysed data from over 5,000 people taking part in cholesterol-lowering trials. These studies utilised a new therapy to reduce cholesterol to much lower levels than previously possible. The team wanted to assess whether reducing cholesterol as low as possible is safe, and whether it was more beneficial than the current levels achieved with existing drugs. The scientists found that dropping cholesterol to the lowest level possible - to levels similar to those we were born with - reduced the risk of heart attack, stroke or fatal heart disease by around one third. "Experts have long debated whether very low cholesterol levels are harmful, or beneficial. This study suggests not only are they safe, but they also reduced risk of heart disease, heart attack and stroke."

In the paper, the scientists examined levels of low density lipoprotein (LDL) cholesterol. This is considered to be 'bad' cholesterol, as it is responsible for clogging arteries. LDL carries cholesterol to cells, but when there is too much cholesterol for cells to use, LDL deposits the cholesterol in the artery walls. Official advice suggests most people should aim to keep their LDL cholesterol at 100 mg/dL or below, though this number can vary depending on a person's risk of cardiovascular disease. In the study, the team analysed data from 10 trials, involving 5000 patients. Most had cardiovascular disease, and already had some furring of the arteries or were at very high risk of furred arteries. All of the patients had previously been diagnosed with high cholesterol, and many were slightly overweight. The average age was 60, and the researchers tracked the patients for between three months and two years. The average cholesterol reading was around 125 mg/dL, and they were all deemed at risk of heart problems or stroke.

Mostly patients were taking a cholesterol-lowering statin therapy, but just over half were also taking an additional novel drug, called alirocumab, every two weeks via a small injection, to further lower cholesterol levels. This drug may be needed when patients' cholesterol levels are not sufficiently lowered by statins. Some patients find their cholesterol levels aren't adequately reduced by statins, possibly because they carry a faulty gene. The combined effect of the new drug and the statin in the trials meant that patients reached very low cholesterol - lower than 50mg/dL. This is comparable to the levels we are born with, but is only achievable in adulthood through medication - lifestyle and exercise alone would not drop levels so low. The researchers found lowering levels of cholesterol reduced the risk of heart attack, stroke, angina or death from heart disease, and that for every 39mg/dL reduction in LDL, the risk reduced by 24 per cent.

Link: http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_16-12-2016-12-53-13

Are Longevity Assurance Therapies only for the Wealthy?

The Life Extension Advocacy Foundation is in the process of reworking their online presence and adding a lot more content. One of the new items is this discussion of the likely trajectory of cost for near future therapies that slow aging or produce rejuvenation, such as the panoply of SENS therapies presently under development. There is a tendency for people to assume, without giving it much thought, that rejuvenation therapies will always be enormously expensive and thus restricted to the wealthy, but this is basically nonsense. Once proven and packaged as a product, the projected types of therapy will be mass manufactured infusions and injections, the same for everyone. They will be administered by bored clinicians, needing little in the way of time from expensive medical staff, and only undertaken once every few years or so. If you look at comparable technologies today, even given the way in which a dysfunctional and highly regulated medical industry piles on unnecessary costs, this class of medicine is not expensive once it gets to the point of widespread availability and standardized manufacture in bulk. Further, consider that this is the case is when the number of patients, while large, is only a tiny fraction of the overall population. When the target market is instead everyone over the age of 40, enormous economies of scale will come into play.

The concern that rejuvenation biotechnologies might cause social disparity and further widen the gap between rich and poor is one of the most commonly raised ones, probably second only to concerns of overpopulation. Like many others, this concern may appear valid at first, but it does not survive careful analysis. The underlying assumption of the argument we are discussing is that rejuvenation therapies would be so very expensive that only rich people would be able to afford them, thus fracturing the world into the ever-young, ever-healthy rich ones, and the poor, sick, old ones with no access to these technologies. It is very likely that rejuvenation therapies will be quite expensive initially due to a number of factors. However, even if we can initially assume a high cost for rejuvenation biotechnologies, we need to keep in mind that new technologies generally start off as very expensive and eventually become affordable and widespread.

For instance, it took only 15 years for full genome sequencing cost to drop from $100 million to $300, making personalised medicine a reality globally. In the field of medicine, there are several other examples of this same trend of falling cost and prices. The drug metformin, used for the treatment of type 2 diabetes (and probably the first drug to slow down aging in healthy people, which is currently the subject of the TAME clinical trial), was initially expensive but eventually its price plummeted to a few dollars. Its price fell from $1.24 per tablet in 2002 to 31 cents in 2013. Similarly, improvements in technology have drastically reduced the costs of research diagnostics, and the advent of remote technology has allowed a cost reduction for both patients and hospitals as specialists can be contacted at a distance. As an example, this means hospitals do not need to have radiologists in location all the time, but can instead remotely send them patient data for analysis and thus only pay for each individual service; this, in turn, implies potentially cheaper services for the patients as well.

Technology typically becomes much cheaper as time goes by; there is no reason to believe the same would not be true of rejuvenation technologies, especially when one takes into account an extremely strong economic motivator: The market for rejuvenation biotechnologies would be the largest in history. Every single person in the world has aging and is thus a potential customer. It is of course very likely that those with wealth and therefore greater means will obtain cutting edge technology first (as we have seen repeatedly historically) before everyone else. However, one should consider that those early adopters are playing "guinea pig" and in effect are paving the way for the masses and helping developers offset the costs incurred during the development process due to paying premium prices for early access to these technologies.

If, for the sake of the argument, we assumed that rejuvenation biotechnologies could somehow be an exception to the trend of falling prices in technology, we would need to decide whether people ending up paying for their own rejuvenation therapies is more a realistic scenario than governments subsidizing the treatments, partly or wholly. The majority of countries in the world have universal healthcare systems that take care of their citizens or residents health needs either for free or for a nominal fee. These costs are offset by taxes which ensure the health service is able to provide this level of care to all. Presently, health expenditures for the elderly constitute a considerable burden on a country's economy. Although the elderly have already contributed wealth to society when they were younger, they often stop doing so when they retire. The desired result of rejuvenation therapies leads to a much better scenario. If rejuvenation therapies are reapplied with proper timing, no individual would ever reach a state of age-related decay and poor health that could make him or her unfit for work. Consequently, the costs of treating age-related diseases using current medicine could be reduced with the arrival of more robust therapies offered by rejuvenation biotechnology. Such rejuvenation therapies aim to prevent a plethora of diseases before they manifest, potentially saving money. However, even if the costs are the same and we are simply trading one set of medicines for another, the benefit to health, quality of life and productivity makes it more than worth it regardless.

Link: http://www.lifeextensionadvocacyfoundation.org/education/only-the-rich/

Testing the Quality of Brain Preservation by Exercising Neurotransmitter Functions

You, your self, consists of the slowly shifting structural pattern of matter that holds the data of the mind. That structure is thought to reside in the synapses that connect neurons in the brain, though there is some debate on this topic and final confirmation still lies somewhere in the future. Survival after cold water drowning, in which the brain ceases all activity for a time but nonetheless carries on after rescue, adequately demonstrates that the basis of the mind is physical, not ephemeral, however, no matter where exactly it is to be found in the fine structure of brain tissue. This is important, because it means that an individual is only finally, absolutely dead and gone when that structure is destroyed. A person can be minutes past present definitions of clinical death, but still exist, still be dying in the sense that the structures of the mind are being destroyed by ischemia. Past that span of minutes it gets far more sketchy and unknown as how much of the self remains. That is a hard question to answer absent a definitive location for that data. What if the destruction can be halted, the brain preserved, however?

Preservation of the brain, the self, is the point of the cryonics industry. As soon as possible following death, the brain is cooled by stages and perfused with cryoprotectant. The result is vitrification with minimal ice crystal formation, a method demonstrated to preserve the fine structure of brain tissue, assuming a sufficiently comprehensive perfusion was achieved. There are examples of vitrified and thawed nematode worms retaining memory, and the cryobiology field is working towards reversible vitrification of organs to improve the logistics of organ transplantation and tissue engineering. When a patient is cryopreserved by a cryonics provider, the vitrified body and brain is stored in liquid nitrogen, awaiting a future with sufficiently advanced technology to undertake restoration. The individual is clinically dead, but not gone. The mind still exists, paused, and while that remains true we can envisage future combinations of molecular nanotechnology and regenerative medicine that could achieve a restoration to active life. Will that come to pass? Hopefully so, but nothing is certain. You roll the dice and look for the best odds, just as in any other decision. The odds following cryopreservation are infinitely better than those following burial or cremation. No-one comes back from oblivion.

A potential alternative to cryonics is plastination. This uses chemical fixation at room temperature instead of low-temperature vitrification, halting all biological processes by binding them up in fixative molecules while preserving the original molecular structure of the tissues. The technology needed to restore plastinated tissue is likely to be much more advanced than that needed to restore a vitrified brain: there are many more chemical reactions that need to be undone, molecule by molecule, and at the same time as kick-starting the normal cellular processes. At the present time there is no plastination industry akin to the cryonics industry that preserves people following death, but this may be nothing more than a historical accident. If the founders of the cryonics movement in the 1960s and 1970s had the chemistry background to settle on plastination, then we'd be looking back at decades of increasing experience in that technology instead. As the Brain Preservation Technology Prize contest of recent years illustrated, there isn't any great difference between the two approaches in terms of preservation of fine structure in brain tissue. Both can achieve the goal given a good methodology and absence of complications - and in both cases the burden and the challenge of restoration is placed upon future researchers. Which is fine; preserved patients can wait it out for as long as the preservation organizations continue.

How do we assess the quality of a preservation method, however? The primary methodology at the moment is the use of electron microscopy to assess the small-scale structure of neurons and synapses. It is possible to raise objections to this as a measure of success, but it is a good starting point. If significant disruption is seen here, then there is little point in looking any closer until we have a much better idea as to exactly which structures encode data. Another possible approach is to work with studies in lower species that can be preserved and restored, and assess their cognitive function after the process. That isn't possible for plastination, but has been done for vitrified nematode worms, as I mentioned above. Beyond this, what else can be attempted? In the research linked below, a novel approach is assessed in one of the common forms of plastinated brain tissue. The researchers manage to exercise some of the functionality of the preserved brain cells despite the chemical fixation process. If it can be replicated, this strikes me as a very compelling demonstration, and one that should certainly be expanded upon. I would be most interested to learn whether or not this sort of approach could be attempted in vitrified brain tissue at liquid nitrogen temperature - unfortunately I know far too little about this area of science to even guess at how one would go about such a task, or the degree to which it is possible at that temperature.

When Is the Brain Dead? Living-Like Electrophysiological Responses and Photon Emissions from Applications of Neurotransmitters in Fixed Post-Mortem Human Brains

The fundamental principle that integrates anatomy and physiology can be effectively summarized as "structure dictates function". This means the functional capacities of biological substrata are determined by the chemical composition, geometry, and spatial orientation of structural subcomponents. As the heterogeneity of structure increases within a given organ, so does the functional heterogeneity. Nowhere is this more evident than in the human brain. It can be described as a collection of partially-isolated networks which function in concert to produce consciousness, cognition, and behaviour. It also responds to its multivariate, diversely energetic environment by producing non-isotropic reflections within its micrometer and nanometer spaces. The specific spatial aggregates of these dendritic alterations result in processes that have been collectively described as memory: the representation of experience.

When structures of the brain undergo changes sufficient to terminally disrupt these functional processes and the individual is ultimately observed to lose the capacity to respond to stimuli, the brain is said to be clinically dead. This state has been assumed to be largely irreversible. It should be noted that the specific criteria which must be achieved in order to ascribe death to an individual are not universal and exhibit a significant degree of non-consensus. The precise point beyond which the brain is no longer "living", a threshold which remains unidentified, is perhaps less definite than has been historically assumed. Without life support systems, either endogenously in the form a cardiovascular network or exogenously in the form of mechanical aids, the brain degenerates progressively until full decomposition and dissolution. Complete loss of structure is strongly correlated with the complete loss of function. When the brain is dead and the tissue has lost its structural integrity, the individual is assumed to no longer be represented within what remains of the organ.

If, however, the brain is immersed within certain chemical solutions before degeneration and decomposition, the intricate and multiform structures of the human brain can be preserved for decades or perhaps centuries. The gyri and sulci which define the convex and concave landscapes of the brain's outer surface as well as the cytoarchitectural features of the cerebral cortex remain structurally distinct. The deep nuclei and surrounding tract systems remain fixed in space, unchanging in time. Though structurally intact, the functions of the brain are, however, still considered to be absent. It has been assumed that the chemical microenvironment (e.g., pH, nutrient content, ionic gradients, charge disparities, etc.) of both cells and tissues within the preserved brain must be altered to such a degree to prevent degradation that these spaces no longer represent those which underlie the cellular processes which give rise to normal human cognition and behaviour.

The principle of anatomy and physiology which describes the relationship between structure and function would hold that in the presence of structural integrity so too must there be a functional integrity. If the structure-function relationship is a physical determinant, functional capacities should scale with structural loss and vice versa. Therefore the maintenance of structure subsequent to clinical death by chemical fixation could potentially regain some basic function of the tissue to the extent to which structure and function are intimately related. Here we present lines of evidence that indicate brains preserved and maintained over 20 years in ethanol-formalin-acetic acid (EFA), a chemical fixative, retain basic functions as inferred by microvolt fluctuations and paired photon emissions within the tissue. They are both reliably induced and systematically controlled by the display of electrical and chemical probes which include the basic inhibitory and excitatory neurotransmitters or their precursors. Each of these profiles exhibit dosage-dependence and magnitude dependences that are very similar to those displayed by the living human brain. As neuroscientists we have been taught or have assumed that the fixed human brain is an unresponsive mass of organic residual that has replaced what was once a vital, complex structure that served as the physical substrate for thought, consciousness, and awareness. The results of the present experiments strongly suggest we should at least re-appraise the total validity of that assumption.

MicroRNA Differences Across the Course of Aging Correlate with Life Span

A cell might be considered a state machine whose state and state transitions are determined by the amounts of various proteins present. The process of gene expression by which genetic blueprints are converted into proteins is enormously complex, and a large fraction of the various types of molecule assembled inside a cell have much more to do with manipulating the steps involved in gene expression than with other cellular activities. Every facet of gene expression, from the pace at which proteins are produced to which protein is produced when there are multiple options for a given stretch of DNA, is subject to a constant, ever-changing set of interactions, feedback loops between production and influence over production. Researchers are these days putting a great deal of effort into mapping the classes of protein machinery involved in regulation of gene expression, such as microRNAs (miRNA), and some of that work is focused on aging:

Biomarkers of aging are biological parameters that change in a predictable direction with aging in most individuals and, when assessed early in life, may predict subsequent longevity better than chronological age alone. Beyond their prognostic utility, the discovery of biomarkers of aging is attractive because they may shed light into the intrinsic mechanism of aging as a biological process. Identifying biomarkers of aging may also provide insight into the biological mechanisms that accelerate or decelerate aging. miRNAs have emerged as important regulators of biological mechanisms that are relevant for aging. miRNAs are short non-coding RNAs that regulate gene expression. With over 1800 human miRNAs reported, miRNAs influence a wide range of biological functions, such as stem cell self-renewal, cell proliferation, apoptosis, and metabolism.

Profiles of miRNAs found in plasma and serum have been linked to numerous cancers, cognitive impairment, Alzheimer's disease and other neurodegenerative disorders, and other pathologies, indicating that miRNAs are a new class of biomarkers of human diseases present in blood. Because of the close relationship between these diseases and longevity, miRNAs may also serve as biomarkers of human aging. Our prior work has shown that miRNAs can serve as genetic biomarkers of aging in the nematode C. elegans. Because miRNAs and aging genetic pathways are conserved from nematodes to humans, an increasing number of human miRNA studies have been carried out over the past several years. These studies have shown differential abundance of multiple miRNAs in peripheral blood mononuclear cells (PBMCs) or serum/plasma when comparing younger and older adults. We used miRNA PCR arrays to measure miRNA levels in serum samples obtained longitudinally at ages 50, 55, and 60 from 16 participants of the Baltimore Longitudinal Study of Aging (BLSA) who had documented lifespans. We compared miRNA expression changes not only across (i.e., between older and younger participants) but also within participants (using the three samples taken at different ages from each individual). In accordance with recent research that found a strong association between circulating miRNAs and human aging, our study suggests that circulating miRNAs are biomarkers of longevity.

Many interesting expression profiles were observed between study participants with different lifespans. For example, when comparing samples analyzed at age 50 between the long-lived and short-lived subgroups, we identified the 10 most differentially higher and lower expressed miRNAs. The most upregulated miRNA in long-lived participants, miR-373-5p, is part of the miR-373 family, which functions as a tumor suppressor in breast cancer. The most downregulated miRNA in long-lived participants, miR-15b-5p, has been found to be upregulated in oral cancer cells. Because lifespan is a complex trait characterized by escaping, delaying, or surviving fatal age-related diseases, including cancers, further scrutiny of the potential roles of the identified miRNAs in human aging is of great importance and interest. Six of the nine miRNAs (miR-211-5p, 374a-5p, 340-3p, 376c-3p, 5095, 1225-3p) may serve as useful biomarkers, as each of the six miRNAs were correlated with lifespan and were significantly up- or downregulated. Future studies can identify how examining expression of multiple miRNAs simultaneously versus one or a few miRNAs individually would affect these correlations. While some miRNA biomarker or disease-association studies have found significant correlations only by analyzing a profile of expression of multiple miRNAs, our study did identify miRNAs that individually correlate with lifespan. Further, it is striking that miRNA expression at ages 50, 55, and 60 correlates with the eventual, quite varied lifespans of the 16 participants in our pilot study.

Link: http://dx.doi.org/10.18632/aging.101106

Arguing for Some Clonal Expansion of T Cells in the Aging Immune System to be a Beneficial Adaptation

Growth in the clonal expansion of immune cells, the creation of many similar cells of the same lineage, and a reduction in the diversity of such lineages, is characteristic of the aged, dysfunctional immune system. The context in which this is usually discussed is the way in which the proportion of memory T cells, particularly those devoted to persistent pathogens such as cytomegalovirus that cannot be effectively cleared from the body, expands at the expense of other types of immune cell. An immune system burdened with too many memory cells focused on just a few pathogens is one that cannot effectively carry out all of its other tasks. In the research here, however, the authors argue that some forms of this age-related clonal expansion represent an attempt by the immune system to compensate for the damage and disarray of aging. Interestingly the class of cells examined here are senescent, and most other evidence suggests that various forms of senescent immune cells are not beneficial - they produce harmful effects, just like other cells do when they fall into a senescent state.

Inasmuch as immunity is a determinant of individual health and fitness, unraveling novel mechanisms of immune homeostasis in late life is of paramount interest. Comparative studies of young and old persons have documented age-related atrophy of the thymus, the contraction of diversity of the T cell receptor (TCR) repertoire, and the intrinsic inefficiency of classical TCR signaling in aged T cells. However, the elderly have highly heterogeneous health phenotypes. Studies of defined populations of persons aged 75 and older have led to the recognition of successful aging, a distinct physiologic construct characterized by high physical and cognitive functioning without measurable disability. Significantly, successful agers have a unique T cell repertoire; namely, the dominance of highly oligoclonal αβT cells expressing a diverse array of receptors normally expressed by NK cells. Despite their properties of cell senescence, these unusual NK-like T cells are functionally active effectors that do not require engagement of their clonotypic TCR.

The accumulation of NK-like CD28null T cells with advancing age represents a remodeling of the immune repertoire as a compensatory mechanism for the general age-related losses in conventional T cell-dependent immunity. There is thymic atrophy with age leading to impaired production of new naïve T cells, making older adults unable to respond to new and emerging pathogens in an antigen-specific manner. With antigenic exposure through life, there is progressive contraction of the naïve T cell compartment, with corresponding expansion of memory and senescent T cell compartment. These events over the lifespan result in the contraction of diversity of the clonotypic TCR repertoire. With cycles of expansion and death of T cells during antigenic challenges, the phenomenal accumulation of apoptosis-resistant CD28null NK-like T cells is likely a protection against clinical lymphopenia, which is very rare among older adults.

The acquisition of a diverse array of NK-related receptors on CD28null T cells maintains immunologic diversity in old age. There is co-dominant expression of diverse NK-related receptors along clonal lineages of CD28null T cells in late life. This is in stark contrast to the conventional clonotypic TCR diversity that is characteristic of the young. Signaling of these NK-related receptors effectively imparts an innate function to aged T cells; hence, we had originally introduced the term "NK-like T cells" to emphasize their NK-related receptor-driven, TCR-independent effector function. NK-like T cells compensate for the corresponding age-related functional loses in the NK cell compartment. Induction of NK-related receptors on T cells may not be surprising since T cells and NK cells originate from a common lymphoid progenitor. Thus, inducibility of NK-related receptors in senescent CD28null NK-like T cells is consistent with functional plasticity of T cells. Although the intricacies of T cell plasticity are still being investigated, such plasticity re-directs the elaboration of effector activities to ensure a vigorous immunity. In old age, signaling of effector activities of NK-like T cells through NK-related receptors is an adaptation of the aging immune system. Such adaptation is a way to maintain immune homeostasis despite the inefficiency of classical TCR signaling and the contraction of diversity of the repertoire of clonotypic TCRs. NK-like T cells are highly resistant to cell death and may represent Darwin's "fittest" lymphocytes that contribute to immune function into old age.

The expression of NK-related receptors along clonal lineages of CD28null T cells with aging clearly represents a reshaping or remodeling of the immune repertoire. T cell signaling through these receptors independent of the TCR also illustrates the emerging theme that cell senescence may not necessarily be synonymous with dysfunction. One scientific challenge is to determine what drives the induction of diversity of expression of NK-related receptors on T cells with advancing age. Another is to determine whether the TCR-independent effector function of NK-like T cells translates into vigorous immune defense and/or immune surveillance in late life.

Link: http://dx.doi.org/10.3389/fimmu.2016.00530

Temporarily Applying Pluripotency Reprogramming Factors to Adult Mice

Today's interesting news, doing the rounds in the popular press and being gleefully misinterpreted along the way, is that, working in mice, researchers have induced temporarily increased levels of the proteins used to reprogram normal cells into pluripotent stem cells. This produced a number of short term benefits to regeneration and metabolism, though the long-term results on life span remain to be assessed. Cancer and regeneration are two sides of the same coin, and it is thought that the characteristic decline in stem cell activity with age is part of an evolved balance between risk of cancer and risk of tissue failure. Many of the methods of globally spurring greater regeneration either definitely or theoretically carry the risk of cancer. Stem cell therapies and telomerase gene therapies fall into this categories, though on the whole the cancer risk in practice has so far turned out to be lower than the cancer risk in theory. The reasons for this remain to be fully explored. Nonetheless, the whole complex system of a few stem cells with unlimited replication supporting a tissue of many somatic cells with tightly limited replication that exists in near all species came into being in the evolutionary context of cancer. We depend upon biological structures that are self-repairing and resilient in many ways, but that are very vulnerable to cellular malfunctions of uncontrolled growth that distort the structure and disrupt correct function. So where we are less self-repairing and resilient than we might be, cancer is the first and most obvious culprit when considering the evolutionary history that created us.

It has been a decade since researchers first figured out how to reprogram normal adult cells into induced pluripotent stem cells, capable of forming any cell, but likely to do who knows what if put into the context of living tissue. Reprogramming occurs in a cell culture, using a cell sample, not in a living organism. This reprogramming actually involves surprisingly few changes, dialing up the gene expression of a few specific proteins, with the first attempts using Oct4, Sox2, cMyc, and Klf4. The use of induced pluripotent stem cells in medicine is a matter of developing a methodology that will differentiate the pluripotent cells into the desired type of stem or progenitor cell appropriate to the tissue in question, using the patient's own cells as a starting point so that the resulting therapeutic cells are matched perfectly. That is fairly safe, given suitable testing, and will eventually provide a cost-effective source of all the cells needed for the next generation of regenerative medicine and tissue engineering. The cells put in place match those already present in the tissue, and should pick up on the same environment of signals and undertake the appropriate work of regeneration. Delivering pluripotent stem cells as-is, on the other hand, is just asking for cancer: it is more or less the same thing as putting precancerous cells into the patient. There is no control or guidance, and what happens next is up to the hand of fate.

Given this, one would think that taking the next step and using gene therapy to upregulate the reprogramming proteins in a living individual would be even worse. In addition to a whole bunch of newly pluripotent cells, you have newly pluripotent cells appearing in random locations and changed from random cells with random levels of preexisting damage. None of this sounds particularly safe. In fact, that experiment has been carried out in mice, and as you might expect the result is the development of cancers. The newly created pluripotent cells start building whatever springs to mind, wherever they happen to be. However, there are several examples we can point to in which dialing up protein production permanently is disastrous, but turning it up intermittently is quite beneficial. One good example is the tumor suppressor gene p53, which if producing proteins all the time will, in addition to even more effectively reducing cancer risk, accelerate aging by suppressing processes that are also necessary to regeneration and tissue maintenance. Cancer and regeneration use the same mechanisms - one is simply more regulated than the other. Most of the tumor suppression genes that have been cataloged target these shared mechanisms. Yet producing additional p53 only when regulatory processes determine it is needed, suppresses cancer more effectively without accelerating aging.

In this context the researchers here use a methodology of temporarily increasing expression of the pluripotency genes Oct4, Sox2, cMyc, and Klf4 in mice. They do this in cell cultures, then in mice with an accelerated aging disorder - actually a dysfunction of the cellular structure akin to that in human progeria - and then in normal aged adult mice. I think it a good idea to ignore the first two of these. Cell cultures are not living animals, and we should usually pay little attention to studies on accelerated aging models for the same reason we should pay little attention to studies in poisoned mice. Progeria and poisoning are both conditions that have little relevance to normal aging, being an accumulation of cell damage that doesn't occur to any large degree in normal aging, so it is often very hard to determine whether or not the results are in any way useful. If you produce a lot of damage and then help work around that damage, but none of the above actually happens in the course of ordinary aging, what does that say? The answer depends on details specific to each case that most of us are not knowledgeable enough to assess.

Fortunately here the researchers did undertake a study in normal mice. Unfortunately it was only a short-term study, so considerations of life span and longer term outcomes, such as cancer rate, will have to wait. Still, as an additional data point in the larger picture of what can be done to enhance regeneration in mammals, it is interesting. We can consider all sorts of plausible candidate mechanisms that have been explored in past years and likely overlap with those involved in the outcomes produced by stem cell transplants and telomerase gene therapies. That said, this upregulation of pluripotency factors is certainly something that I'd put in the "very unwise" bucket, should you find yourself in the position to undergo such a gene therapy in the years ahead. It is much more risky than telomerase gene therapy, and that in and of itself looks like something to skip until more data on the outcomes in larger mammals arrives.

Turning back time: Salk scientists reverse signs of aging

As people in modern societies live longer, their risk of developing age-related diseases goes up. In fact, data shows that the biggest risk factor for heart disease, cancer and neurodegenerative disorders is simply age. One clue to halting or reversing aging lies in the study of cellular reprogramming, a process in which the expression of four genes known as the Yamanaka factors allows scientists to convert any cell into induced pluripotent stem cells (iPSCs). Like embryonic stem calls, iPSCs are capable of dividing indefinitely and becoming any cell type present in our body. "What we and other stem-cell labs have observed is that when you induce cellular reprogramming, cells look younger. The next question was whether we could induce this rejuvenation process in a live animal."

While cellular rejuvenation certainly sounds desirable, a process that works for laboratory cells is not necessarily a good idea for an entire organism. For one thing, although rapid cell division is critical in growing embryos, in adults such growth is one of the hallmarks of cancer. For another, having large numbers of cells revert back to embryonic status in an adult could result in organ failure, ultimately leading to death. For these reasons, the team wondered whether they could avoid cancer and improve aging characteristics by inducing the Yamanaka factors for a short period of time. To find out, the team turned to a rare genetic disease called progeria. Both mice and humans with progeria show many signs of aging including DNA damage, organ dysfunction and dramatically shortened lifespan. Moreover, the chemical marks on DNA responsible for the regulation of genes and protection of our genome, known as epigenetic marks, are prematurely dysregulated in progeria mice and humans. Importantly, epigenetic marks are modified during cellular reprogramming.

Using skin cells from mice with progeria, the team induced the Yamanaka factors for a short duration. When they examined the cells using standard laboratory methods, the cells showed reversal of multiple aging hallmarks without losing their skin-cell identity. Encouraged by this result, the team used the same short reprogramming method during cyclic periods in live mice with progeria. The results were striking: Compared to untreated mice, the reprogrammed mice looked younger; their cardiovascular and other organ function improved and - most surprising of all - they lived 30 percent longer, yet did not develop cancer. Lastly, the scientists turned their efforts to normal, aged mice. In these animals, the cyclic induction of the Yamanaka factors led to improvement in the regeneration capacity of pancreas and muscle. In this case, injured pancreas and muscle healed faster in aged mice that were reprogrammed, indicating a clear improvement in the quality of life by cellular reprogramming.

In Vivo Amelioration of Age-Associated Hallmarks by Partial Reprogramming

The last decade of scientific research has dramatically improved our understanding of the aging process. The notion that cells undergo a unidirectional differentiation process during development was proved wrong by the experimental demonstration that a terminally differentiated cell can be reprogrammed into a pluripotent embryonic-like state. Cellular reprogramming to pluripotency by forced expression of the Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc [OSKM]) occurs through the global remodeling of epigenetic marks.

Although in vitro studies have been informative, the physiological complexity of the aging process demands an in vivo approach to better understand how reprogramming may affect cellular and organismal aging. Breakthrough studies have shown that cellular reprogramming to pluripotency, although associated with tumor development (e.g., teratoma formation), can be achieved in vivo in mice by the forced expression of the Yamanaka factors. In addition, we and other groups have demonstrated that partial reprogramming in vitro by transient expression of OSKM can induce a dedifferentiated progenitor-like state. Together, these observations suggest that cellular reprogramming may be used to promote tissue regeneration and led us to hypothesize that in vivo partial reprogramming could slow or reverse the aging process and extend organismal lifespan. Here, we report that cyclic in vivo induction of OSKM in a mouse model of premature aging improves age-associated phenotypes and extends lifespan. In addition, we demonstrate the amelioration of cellular phenotypes associated with aging by short-term induction of the Yamanaka factors in mouse and human cells. Finally, we show that short-term expression of OSKM alleviates pancreatic and muscle injury in older wild-type (WT) mice.

Our observations may reinforce the potential role of epigenetic changes as drivers of aging and highlight the plasticity of the aging process, which might be altered by cellular reprogramming in vivo. In addition, our results suggest that aged cells undergo a process of molecular rejuvenation during the initial stages of cellular reprogramming to pluripotency. Failure to erase critical hallmarks of aging may lead to refractory populations of cells and cellular senescence. Due to the complexity of the reprogramming and aging processes, future studies will be necessary to investigate whether partial reprogramming can ameliorate aging hallmarks during physiological aging and to better understand the molecular mechanisms behind this phenomenon. This information will be necessary if we are to develop accurate and efficient epigenetic remodeling strategies toward maximizing the beneficial effects of in vivo reprogramming while avoiding potential risks associated with the in vivo expression of the Yamanaka factors.

Reading the whole of the analysis in the paper, I have to say that I think these researchers have a lot of the picture back to front. Putting epigenetic changes front and center as a primary mechanism in aging, as opposed to a reaction to rising levels of cell and tissue damage, is the cart in front of the horse. Sure, those epigenetic changes cause further problems, but focusing on targeting them won't remove the primary damage that causes aging. It only forces the damaged engine to work harder. Maybe that produces benefits, as it seems to in stem cell therapies that work via signaling to put existing cells back to work, but it isn't solving the real problem.

A Discussion of Calico Labs

Google founded the California Life Company, or Calico Labs, to work on aging, and has put a large amount of money into this project. It is all comparatively secretive, but so far the evidence suggests that this will, sadly, turn out much the same way as the Ellison Medical Foundation, which is to say (a) work on extending the map of all cellular biochemistry relevant to the progression of aging at the most detailed level coupled to (b) attempts to slightly slow aging via pharmaceuticals. The project is headed by someone who has little interest in translational research, the business of bringing therapies to market, and those involved - for the most part - are not people with a track record of paying attention to the SENS program of repairing damage to produce rejuvenation. The SENS research agenda is to my eyes the only viable way forward to produce meaningful extension of healthy life any time soon, and certainly the only way to help older people by turning back aging at later stages. It is also far closer to realization and far less expensive to develop than efforts to safely alter human metabolism to slow the rate at which damage is done. The field of aging research has all too little funding in comparison to its potential, but it doesn't suffer from a lack of fundamental research anywhere near as much as it suffers from a lack of taking what is already well known about the forms of cell and tissue damage that cause aging in order to build therapies here and now.

David Botstein is Calico's chief scientific officer. He is 74, with a grizzled shadow of beard reaching up from his collar. In November, I found him at a lecture hall at MIT, where he offered a rare window onto experiments under way at Calico. Botstein, a well-known Princeton geneticist whom Calico recruited out of near retirement, was in town to celebrate the birthday of a successful former student, now a sexagenarian. "The pleasure is coming to see old friends. The not-so-­pleasure is if these guys are 60, what am I?" In his lecture, Botstein described several technologies - four, in fact - that Calico has for isolating old yeast cells from the daughter cells that bud off them. These old cells are tracked and subjected to a comprehensive analysis of which genes are turned up or turned down, a technique that is Botstein's specialty. Botstein told me Calico is exactly what Google intended: a Bell Labs working on fundamental questions, with the best people, the best technology, and the most money. "Instead of ideas chasing the money, they have given us a very handsome sum of money and want us to do something about the fact that we know so little about aging. It's a hard problem; it's an unmet need; it is exactly what Larry Page thinks it is. It's something to which no one is really in a position to pay enough attention, until maybe us."

Botstein says no one is going to live forever - that would be perpetual motion which defies the laws of thermodynamics. But he says ­Cynthia Kenyon's experiments on worms are a "perfectly good" example of the life span's malleability. So is the fact that rats fed near-starvation diets can live as much as 45 percent longer. The studies Botstein described in yeast cells concerned a fundamental trade-off that cells make. In good times, with lots of food, they grow fast. Under stresses like heat, starvation, or aging, they hunker down to survive, grow slowly, and often live longer than normal. "Shields down or shields up," as ­Botstein puts it. Such trade-offs are handled through biochemical pathways that respond to nutrients; one is called TOR, and another involves insulin. These pathways have already been well explored by other scientists, but Calico is revisiting them using the newest technology. "A lot of our effort is in trying to verify or falsify some of the theories," Botstein says, adding that he thinks much of the science on aging so far is best consumed "with a dose of sodium chloride." Some molecules touted as youth elixirs that can act through such pathways - like resveratrol, a compound in red wine - never lived up to their early hype.

According to Botstein, aging research is still seeking a truly big insight. Imagine, he says, doctors fighting infections without knowing what a virus is. Or think back to cancer research in the 1960s. There were plenty of theories then. But it was the discovery of oncogenes - specific genes able to turn cells cancerous-that provided scientists with their first real understanding of what causes tumors. "What we are looking for, I think above everything else, is to be able to contribute to a transformation like that. We'd like to find ways for people to have a longer and healthier life. But by how much, and how - well, I don't know." Botstein says a "best case" scenario is that Calico will have something profound to offer the world in 10 years. That time line explains why the company declines media interviews. "There will be nothing to say for a very long time, except for some incremental scientific things. That is the problem."

To some, Calico's heavy bet on basic biology is a wrong turn. The company is "my biggest disappointment right now," says Aubrey de Grey, an influential proponent of attempts to intervene in the aging process and chief science officer of the SENS Research Foundation, a charity an hour's drive from Calico that promotes rejuvenation technology. It is being driven, he complains, "by the assumption that we still do not understand aging well enough to have a chance to develop therapies." Indeed, some competitors are far more aggressive in pursuing interventions than Calico is. "They are very committed to these fundamental mechanisms, and bless them for doing that. But we are committed to putting drugs into the clinic and we might do it first," says Nathaniel David, president and cofounder of Unity Biotechnology. This year, investors put $127 million behind Unity, a startup in San Francisco that's developing drugs to zap older, "senescent" cells that have stopped dividing. These cells are suspected of releasing cocktails of unhelpful old-age signals, and by killing them, Unity's drugs could act to rejuvenate tissues. The company plans to start with a modestly ambitious test in arthritic knees. De Grey's SENS Foundation, for its part, has funded Oisin Biotechnologies, a startup aiming to rid bodies of senescent cells using gene therapy.

Link: https://www.technologyreview.com/s/603087/googles-long-strange-life-span-trip/

An Example of Reducing or Altering Cellular Senescence

Researchers have demonstrated a number of genetic and pharmacological approaches that seem to modulate cellular senescence, either by somewhat lowering the number of cells that become senescent or by somewhat reducing the impact of the senescence-associated secretory phenotype (SASP). Senescent cells are one of the root causes of aging. They produce damage and age-related disease through the signals they secrete, which cause inflammation, remodel surrounding tissue structures, and alter the behavior of normal cells for the worse. Many of the methods that over the years have been demonstrated to modestly slow aging in laboratory animals have some sort of effect on the properties of cellular senescence, but a potential therapy based on these methods would have to be far, far more effective in order to compete with selective destruction of senescent cells as an approach to the problem. The cell culture research here is an example of present explorations into altering the processes of senescence rather than simply destroying the unwanted cells, but I can't say that I see it as being all that promising for anything other than the production of greater knowledge of the senescent state.

Cellular senescence is a hallmark of aging and senescent cells accumulate with age in vivo in mammals; this is thought to drive aging by limiting tissue replicative capacity and causing tissue dysfunction. Developing strategies to delay the onset of senescence or remove senescent cells may provide a route to preventing age-related disease. Targeting senescence as a means to combat aging and age-related diseases is, however, challenging due to its antagonistically pleiotropic nature - any treatment needs to limit the deleterious impacts of senescent cells without impacting the potent barrier against tumorigenesis. While caloric restriction has been reported to extend healthspan in macaques, the most promising candidate for a longevity therapeutic in mammals is rapamycin.

Rapamycin mechanistically acts by binding the protein FKBP12, producing a complex which can bind and inhibit mTOR. mTOR constitutes the point at which diverse environmental signals are coordinated into a cellular response, regulating pathways including cell growth, proliferation, survival, motility and protein synthesis. mTOR is present in two complexes in metazoa, mTORC1 and mTORC2, which have different components and functions. Rapamycin inhibits mTORC1, but chronic treatment may also disrupt mTORC2. While rapamycin extends lifespan in mice even when administered in middle age, it has significant side-effects that may limit its use in humans. We have therefore explored the potential of second generation rapalogs i.e. pharmacological agents that inhibit mTORC but act not through binding to FKBP12 but instead as mTORC-specific ATP mimetics. AZD8055 is an ATP-competitive inhibitor of mTOR kinase in both mTORC1 and mTORC2. AZD8055 has anti-proliferative effects similar to those of rapamycin and has been taken forward into clinical trials against various forms of cancer.

Here, we test whether acute mTORC inhibition can alter features of senescence in cells that have already undergone a large number of population doublings (PD) - as they are about to undergo senescence but are currently still proliferating, we term these populations 'near-senescent'. Such high cumulative PD (CPD) near-senescent cells show many signs characteristic of senescence including increased size and granularity, SA-β-gal staining, high lysosomal content and accumulation of actin stress fibers. They are still capable of cell proliferation, albeit with a reduced rate of proliferation compared with cells at lower CPD. Here, we test the effect of inhibiting both mTORC1 and mTORC2 using the TOR-specific ATP mimetic AZD8055. Remarkably, we demonstrate significant reversal of major phenotypes of senescence on short term low dose pan-TOR inhibition. We therefore suggest that AZD8055 may prove useful in modulating health outcomes in late life.

Link: https://dx.doi.org/10.18632/aging.100872

Looking Back and Ahead in the Use of Pluripotent Stem Cells in Medicine

There are a few papers and commentaries that you might find interesting in the latest issue of Regenerative Medicine. The one I'll point out here offers a retrospective and a forecast for the use of pluripotent stem cells in medicine. It is authored by one of the more outspoken figures from the last decade of research and development, but is worth reading regardless of that point. All industries tend to follow what has come to be known as a hype cycle as they reach critical mass and transition into broad adoption and large scale development. Stem cell medicine as a whole had its initial peak of attention and overhyped expectations, followed by a consequent period of disillusionment as people realized that it wasn't a silver bullet for everything, and that, yes, there was actually going to be quite a lot of work involved in turning the new knowledge of stem cell biology and promising early results in transplant therapies into the bigger, better next generation of medicine. All of that largely took place almost decade ago. As is always the case, it is after the initial hype and crash is out of the way that the real work begins in earnest, and at a far greater scale. The ongoing development of cell therapies is now well into this quieter, more productive period of growth; the engineering of reliable treatments that improve upon the prior state of the art.

Not all cell therapies are relevant to aging and rejuvenation, but since it is the case that comparatively simple forms of stem cell transplant can produce a number of benefits in age-damaged tissues, and are an incremental improvement over existing therapies for a number of conditions, a large fraction of the development initiatives in this industry are focused on age-related disease. So far the most reliable benefits are produced by classes of therapy in which stem cells provide signaling that reduces inflammation and spurs greater regenerative activity in native cell populations. In most cases the transplanted cells don't integrate or stick around for the long term, however. Stem cell treatments for the sort of inflammatory joint issues prevalent in the old are an example of the type, as are most treatments involving mesenchymal stem cells. Regeneration of internal organ damage and effective treatment of age-related disease has proven to be a more elusive goal, however. Benefits are observed, but reliability is a real challenge. A great deal of the data is hidden from view, given that most patients are treated via medical tourism and formal trials are an expensive and slow business.

Given all of this, it is fair to say that a large fraction of the effort and funding in stem cell medicine has little to do with addressing aging directly. The therapies are compensatory in nature, and do not target the causes of degenerative aging relevant to the space of cell therapies. Insofar as aging is in part a problem of cell loss on the one hand and a mix of damage and declining activity in stem cell populations on the other, we would want to see cell therapies that can replace lost cells (such as muscle cells in order to reduce frailty) and deliver fresh new stem cell populations that will integrate into tissues and take up the work of their predecessors. The latter is the preferable approach, as new stem cells that work as they did when youthful should solve the problem of lost cells and weakened tissues as a matter of course. The challenge here is that it appears that much of the problem of stem cell decline in aging is driven by changes in signaling in tissue, which in turns results from the varied forms of cell and tissue damage that cause aging. Stem cell decline is a reaction to damage, possibly an evolved response that serves to balance death by cancer on the one hand and death by failing organs on the other. Replacing stem cell populations with new, pristine cells is certainly needed, but will probably be of only limited benefit without inroads into other forms of rejuvenation therapy that can lift the burden of damage and thus revert the signaling environment to a more youthful state.

Pluripotent stem cells: the last 10 years

Pluripotent stem cells (PSCs) can differentiate into virtually any cell type in the body, making them attractive for both regenerative medicine and drug discovery. Over the past 10 years, technological advances and innovative platforms have yielded first-in-man PSC-based clinical trials and opened up new approaches for disease modeling and drug development. Induced PSCs have become the foremost alternative to embryonic stem cells and accelerated the development of disease-in-a-dish models. Over the years and with each new discovery, PSCs have proven to be extremely versatile.

In 2006, it had been 8 years since the initial isolation of human embryonic stem cells (hESCs) and incremental scientific progress was being made. However, ethical dilemmas regarding the use and/or destruction of human embryos as well as legislative barriers in several countries hindered hESC research endeavors. Moreover, the need to source several hundred embryos for the creation of hESC lines to cover the diversity of human leukocyte antigen (HLA) phenotypes made clinical translation of embryonic stem cell (ESC) based therapies seem difficult. This situation precipitated major initiatives to find alternatives. Single blastomere technology is one such alternative; it was developed in 2006 as a nondestructive ESC derivation method and was first demonstrated for mouse ESCs, then adapted for human ESCs in the same year. With this technique, a single cell or 'blastomere' is isolated from a morula (8-cell) stage embryo and, after culture and expansion, can give rise to an ESC line.

Somatic cell nuclear transfer (SCNT) is another alternative for generating hESCs without the destruction of naturally made embryos. This technique has been used successfully in other species such as calves, pigs and mice since the late 1990s and early 2000s, yet for various reasons including the availability of federal funding, institutional review board (IRB) requirements and public sentiment, it took until 2013 for it to be successfully applied to humans. In SCNT, the nucleus of an unfertilized egg is removed and replaced with the nucleus from a somatic cell. Precise culture conditions coupled with maternal factors within the egg promote the reprogramming of the somatic cell nucleus back to a pluripotent state and can give rise to an ESC line. Despite these successes, SCNT has not been widely used for ESC derivation due to the need for high-quality eggs and precise microsurgical techniques. Moreover, the requirement for egg donation is a significant barrier to its widespread use.

Arguably the most important alternative to conventional methods for hESC generation was the invention of induced PSC (iPSC) technology in 2006 and its application to human cells in 2007. iPSC technology avoids the use and destruction of human eggs and/or embryos altogether, thereby largely circumventing ethical controversy. iPSCs are generated through the reprogramming of somatic cells back to an embryonic-like state; the addition of exogenous reprogramming factors triggers this reprogramming process. iPSC technology revolutionized the field of PSC research. Today, generating iPSCs takes many shapes and forms, with different reprogramming factors, different methods for introducing factors to cells, different starting cell types, among others. The technology has undergone a fascinating evolution from its first report in 2006 to the present day and it will continue to evolve in years to come. In 2009-2011, right around the same time that various second-generation reprogramming methods were being developed, reports were starting to emerge that iPSCs were not equivalent to ESCs and that differentiation potential of iPSCs was either impaired or skewed based on the starting somatic cell type. Differences in the somatic cell type used for reprogramming, the specific reprogramming method employed, as well as the extent of culturing are thought to influence the degree of disparity between various iPSC lines and/or ESCs. Yet, in some instances, epigenetic memory can be reduced or even eliminated through subsequent passaging of iPSC clones, or alternatively by differentiation and secondary reprogramming, whereas errors that arise during reprogramming may be corrected through the use of chromatin modifying drugs. Improvements and modifications made to reprogramming methods over the past decade have helped improve the safety and quality of iPSCs such that the development of iPSC-based therapies is moving forward rapidly. In years to come, the development of iPSC-based therapies may overtake conventional hESC-based ones since their generation does not involve the destruction of embryos or even the use of any unfertilized eggs. This is particularly appealing for the long-discussed generation of banks of HLA-matched PSCs to cover patient diversity on a larger scale and reduce or avoid the need for concomitant immunosuppression.

PSCs may be useful for treating a wide variety of diseases given their ability to differentiate, theoretically, into every cell type in the body. The last 5-6 years have seen the PSC field begin to deliver on this promise, with a handful of clinical trials being approved in spinal cord injury, macular degeneration (AMD), diabetes and heart disease. Starting it off in 2009, Geron received investigational new drug (IND) approval to begin testing its hESC-derived oligodendrocyte precursors, GRNOPC1 in a Phase I trial for spinal cord injury. In 2010, a few months before Geron transplanted GRNOPC1 into its first patient, Advanced Cell Technology received IND approval to begin testing hESC-derived retinal pigment epithelium (RPE) for age-related macular degeneration. Around the same time that ACT's 2014 safety data were being published, Japan's RIKEN Institute successfully transplanted the world's first iPSC-derived therapy into humans. They too chose the eye and (wet) AMD as a first indication but decided to transplant autologous iPSC-derived RPE into patients instead of using an off-the-shelf allogeneic cellular product. Given the risks of first-in-human PSC-based therapies, the eye is considered a logical place to begin developing therapies. First, the eye is a locally contained environment, providing a natural barrier to any potentially deleterious cells spreading systemically. Second, its immune-privileged nature may make it more accepting of transplanted allogeneic cells in the long-term. Third, the lens provides a way to noninvasively image the transplantation site over time and functional readouts such as visual acuity are easy to obtain. Indeed, numerous groups have active trials listed. More than a decade of PSC research and development has also led to clinical trials for PSC-derived therapies in other disease areas. In 2014, Viacyte received IND approval to begin a Phase I/II trial to treat Type 1 diabetes. In addition to the above trials, a PSC-derived therapy was approved for an ischemic heart disease Phase I clinical trial in 2013.

The last decade has also seen incredible progress on the development of other PSC-based therapies, some very close to beginning clinical trials. Several groups have made great progress in generating PSC-derived dopaminergic (DA) neurons for the treatment of Parkinson's disease (PD). A long-standing goal for PSC research has been the in vitro generation of glucose-responsive, insulin-producing mature pancreatic β cells to treat diabetes. In 2014, a new protocol was finally able to overcome this challenge and resulted in the in vitro generation of β cells expressing mature pancreatic β cell markers. PSCs are being developed for therapeutic use in various other diseases as well. For example, autologous iPSCs are being generated for patients with the blistering skin disorder, epidermolysis bullosa as part of a cell replacement strategy. In the eye, retinal progenitors are being developed from both ESCs and iPSCs to use as a cell replacement therapy for retinal degenerative diseases, such as retinitis pigmentosa (RP), whereby transplantation of the progenitors would lead to in vivo differentiation and functional engraftment by mature photoreceptors. PSCs are also being developed to maintain the health of endogenous cells at risk for degeneration in various diseases. For example, iPSC-derived macrophages are being manipulated for therapeutic use in Alzheimer's disease (AD) patients. These macrophages have been engineered to express high levels of the β-amyloid-degrading enzyme, neprilysin 2, in an effort to reduce the burden of disease-associated plaques and spare the health of existing neurons in AD. Similarly, in amyotrophic lateral sclerosis (ALS), iPSC-derived neural stem cells may provide therapeutically useful support to endogenous neurons.

Gene editing technologies have been developed to correct disease-causing genetic mutations, functionally replace and/or knock-out expression of dysfunctional genes. Regardless of the editing system employed, the objectives of PSC-based gene editing endeavors fall into two major categories: improving disease models and drug screening systems through the creation of isogenic controls, and gene editing for cell-based therapies. Proof of principle studies includes a report where Crispr/Cas gene editing was used to correct the mutation of the β-globin gene in iPSCs from a β-thalassemia patient. These corrected iPSCs displayed improved differentiation capacity into various types of hematopoietic progenitors and may be one day used as a source of autologous hematopoietic stem cells for transplantation and repopulation of the hematopoietic system. Similarly, Crispr/Cas9 was used to correct a mutation in the gene encoding the RP GTPase regulator in iPSCs derived from a patient with X-linked RP. These corrected cells could in principle be differentiated into photoreceptors or their progenitors and used in cell replacement strategies for RP patients.

The dramatic progress made over the past decade will almost certainly translate into exciting new advancements in decades to come. First-in-man PSC-based clinical trials have thus far shown that PSC-derivatives are safe to use in humans, and provide the impetus for continued clinical trial testing. To date, trials have almost exclusively employed hESCs, yet that is likely to change in the future. Improvements in iPSC quality should enable these ethically sound alternatives to hESCs to catch up or even pass hESC usage in clinical trials. As differentiation procedures and 3D technologies improve, PSCs will become ever more integral to drug screening efforts and disease modeling, although it is unlikely they will ever fully replace the use of in vivo disease models. Another major advancement that will likely drive PSC research in years to come involves the marriage of gene editing technology with PSCs. The ability to precisely correct disease-causing mutations, create isogenic controls and potentially eliminate immunogenicity of PSC derivatives make gene editing in PSCs an incredibly important endeavor. The PSC field will likely produce additional exciting breakthroughs in the coming decade - advancements that could one day make incurable diseases curable.

A Method to Partially Compensate for Failing Wound Healing in Skin

The healing of wounds in skin falters with age and in conditions such as diabetes for a variety of reasons, some better understood than others. The cells responsible for building the replacement skin lose their coordination and in the worst cases this can lead to wounds that do not heal at all. The research noted here doesn't address the underlying reasons for this failure of healing, the molecular damage of aging, but attempts to work around the problem by providing some of the structure and functions that the cells are failing to achieve on their own, and by delivering signals that are known to generally increase cell performance in growth and regeneration.

A team of researchers has demonstrated for the first time that their peptide-hydrogel biomaterial prompts skin cells to "crawl" toward one another, closing chronic, non-healing wounds often associated with diabetes, such as bed sores and foot ulcers. The team tested their biomaterial on healthy cells from the surface of human skin, called keratinocytes, as well as on keratinocytes derived from elderly diabetic patients. They saw non-healing wounds close 200 per cent faster than with no treatment, and 60 per cent faster than treatment with a leading commercially used collagen-based product.

Until now, most treatments for chronic wounds involved applying topical ointments that promote the growth of blood vessels to the area. But in diabetic patients, blood vessel growth is inhibited, making those treatments ineffective. Researchers have been working with their special peptide - called QHREDGS, or Q-peptide for short - for almost 10 years. They knew it promoted survival of many different cell types, including stem cells, heart cells and fibroblasts (the cells that make connective tissues), but had never applied it to wound healing. "We thought that if we were able to use our peptide to both promote survival and give these skin cells a substrate so they could crawl together, they would be able to close the wound more quickly. That was the underlying hypothesis."

The researchers compared the Q-peptide-hydrogel mix to the commercially available collagen dressing, to hydrogels without the peptide, and to no treatment. They found that a single dose of their peptide-hydrogel biomaterial closed the wounds in less than two weeks. "Currently, there are therapies for diabetic foot ulcers, but they can be improved. Diabetic wound healing is a complicated condition, because many aspects of the normal wound healing process are disrupted." This finding could have big implications for many types of wound treatments, from recovery after a heart attack to healing post-surgery. Accelerated healing times also introduces the added benefit of reducing the opportunity for infection.

Link: https://www.eurekalert.org/pub_releases/2016-12/uotf-sc121216.php

More Evidence for the Importance of BACE1 in Alzheimer's Disease

BACE1 is a target for Alzheimer's therapies as it is involved in the production of amyloid-β. The condition is characterizing by rising levels of this form of amyloid in the brain, which in turn produces a halo of harmful biochemical interactions that damage and kill brain cells. Researchers are working on a range of ways to reduce the amount of amyloid-β, and interfering with its production is one approach, albeit so far not as effective as striving to remove the amyloid, such as via immunotherapies. Here, researchers explore some of the biochemistry surrounding BACE1; cellular machinery never acts in isolation, and there are always relationships linking many different proteins relevant to any mechanism. Thus there are always multiple options and targets when it comes to achieving a specific result in the operation of cells.

Scientists have found that reduced levels of a protein called Rheb result in spontaneous symptoms of memory loss in animal models and are linked to increased levels of another protein known to be elevated in the brains of Alzheimer's disease patients. The researchers investigated the link between Rheb and an important enzyme called BACE1, which is elevated in older adults and people with Alzheimer's disease. "We know that Rheb regulates BACE1, which is a major drug target in Alzheimer's disease. Studies of the autopsied brains of Alzheimer's patients have found a significant reduction in Rheb, so it is possible that an increase in Rheb could reverse the buildup of amyloid plaque or help reduce or even reverse age-related memory loss."

To uncover the impact of eliminating Rheb, researchers put genetically altered mice through a battery of behavior tests beginning at around six months of age. While Rheb depletion did not affect the overall body weight or motor activity of the animals, it did have subtle and selective effects on certain memory tasks they performed, such as navigating a maze and memory recall. The researchers compared these symptoms to memory deficits that occur in humans with Alzheimer's disease and related dementia. They also found that Rheb depletion increased BACE1 levels, which was consistent with previous research showing that higher BACE1 levels may be a contributing factor for memory deficits.

The fact that some research shows that Rheb messenger RNA is induced during protein starvation in fruit flies, led researchers to theorize that a high-protein diet in humans might be a risk factor for decreasing Rheb levels with age, resulting in mild-to-severe cognitive deficits, as seen in animal models. "This is an indication that nutrient signaling might regulate cognitive functions in mammals through alteration of Rheb-BACE1 pathway activity. Overall, our study demonstrates that forebrain Rheb depletion promotes aging-associated cognitive defects. Targeting the Rheb pathway may offer some therapeutic potential for aging- or Alzheimer's disease-associated memory deficits."

Link: http://www.scripps.edu/news/press/2016/subramaniam20161207.html

Can Cellular Senescence be Reversed in the Near Future, and is Reversal Desirable?

Cellular senescence is one of the causes of degenerative aging. Normal somatic cells in adults become senescent at the end of their replicative life span, when they reach the Hayflick limit on cell divisions, or in response to damage or a toxic environment. Most such cells self-destruct or are destroyed by the immune system, but some linger to cause problems, ever more of them over the years. A senescent cell generates a mix of signals known as the senescence-associated secretory phenotype (SASP) that promotes inflammation, damages surrounding tissue structures, and alters the behavior of nearby cells for the worse. Senescence isn't all bad, however: in limited doses, it helps to lower the risk of cancer by shutting down those cells most at risk. It also occurs during wound healing and embryonic development, and plays necessary roles in both of those processes. Nonetheless, cellular senescence helps to kill us as we age, and as more of these cells accumulate in tissues, their presence speeds the progression of many age-related diseases.

Researchers are taking two broad approaches to cellular senescence at the present time. The first is to build therapies that can selectively destroy senescent cells, following the SENS rejuvenation model of periodic removal of damage. If the number of senescent cells is managed so as to keep that count low, then they will not cause further harm. This has the advantage of being straightforward and requiring little further research to put into practice. A range of demonstrated treatments and potential treatments already exist - gene therapies, immunotherapies, senolytic drugs, and so forth - and companies such as Oisin Biotechnologies and UNITY Biotechnology are bringing some of these technologies to the clinic. The second approach is nowhere near as far along, and involves altering the behavior of senescent cells to make the SASP less harmful. There is a long way to go yet in order to produce a decent therapy on this front, and it isn't clear how much potential there is in the present avenues of investigation, or how much more research is required to make meaningful progress. Such a therapy wouldn't remove senescent cells, and therefore would have to be a continual rather than periodic treatment.

There is a third potential approach, however, which is to revert senescent cells back to a normal state of operation. In the ordinary course of events, senescence is thought to be an irreversible state, though there is a substantial grey area here, as nothing is black and white in biochemistry. There may well be different degrees and types of senescence, similar outcomes produced by different balances of the same varied collection of processes and triggers. I think it highly unlikely that the switch for senescence boils down to one controlling protein and one configuration. That said, cells are state machines and substantial reprogramming of that state has already been demonstrated, such as for induced pluripotency. Given sufficient understanding of the machinery and the signals involved, it should be possible to turn a senescent cell into a perfectly normal cell. There is the caveat that it will probably just turn right back again if the stimulus or damage that provoked the change in the first place is still around, however. Thus any practical approach to revert senescence is likely only useful if accompanied by other forms of repair or alteration, such as lengthening of telomeres to push the cell back from the Hayflick limit. It is an open question as to whether or not this sort of approach would cause further problems by putting damaged and older cells back into circulation, but to a certain extent that question is in the process of being answered by work on telomerase gene therapies and first generation stem cell therapies, both of which appear to produce that outcome to some degree. This is all highly speculative, however - there is a lot of work left to be accomplished to turn arguments and evidence into solid facts.

From my point of view none of this is really worth the effort for therapeutic development given that senescent cells can be destroyed to produce benefits, and anything other than destroying them is going to be much harder to achieve. It is of course useful from a pure science perspective; it adds to the map of metabolism and the way in which cellular biochemistry interacts with aging. With that in mind, the paper linked below is an example of researchers investigating some of the machinery that forms the switches and triggers that determine whether or not a cell adopts a senescent state. At this point the cutting edge of cellular biochemistry has moved well past simpler considerations of genes and proteins and is delving into the highly complex interactions that take place inside the processes of gene expression, wherein the genetic blueprint is converted into one or more proteins. This has numerous stages, and at every stage there is a dance of various regulatory molecules also produced from DNA. The closer that researchers look, the more there is to be mapped.

Identification of senescence-associated circular RNAs (SAC-RNAs) reveals senescence suppressor CircPVT1

Cellular senescence is a state of indefinite growth arrest triggered by exposure of a cell to stress-causing stimuli. When the stress signal arises from successive rounds of replication causing gradual shortening of telomeres, which exposes telomeric DNA and triggers a DNA damage response, the ensuing program is named replicative senescence. When the stress signal comes from other sources of damage, such as oxidants, radiation, heat, activated oncogenes, or toxins, the ensuing program is named stress-induced senescence. Senescence is characterized by increased activity of the tumor suppressor TP53, higher levels of its transcriptional target p21/CDKN1 and the CDK inhibitor p16/INK4A, and activation of the p16 target retinoblastoma (pRB). Senescent cells have a complex impact on human physiology and pathology. Some effects of senescent cells are beneficial, such as tissue remodeling, wound repair, and growth suppression of potentially oncogenic cells. However, many effects of senescent cells are believed to be detrimental. Besides causing tissue dysfunction, senescent cells exhibit a senescence-associated secretory phenotype (SASP), whereby they produce and secrete inflammatory cytokines and chemokines, matrix metalloproteases, and growth and angiogenic factors. The accumulation of senescent cells has been associated with disease processes such as sarcopenia, arthritis, cancer, diabetes, and neurodegeneration.

MicroRNAs (miRNAs) are ∼22-nucleotide long noncoding (nc)RNAs that form part of the RNA-induced silencing complex (RISC), within which the RNA-binding protein (RBP) AGO2 binds microRNAs directly. MicroRNA-RISC complexes influence protein expression patterns through the interaction of the microRNA with subsets of mRNAs via partial complementarity, generally leading to reduced stability and/or reduced translation of the mRNA. By influencing protein expression patterns, microRNAs have been implicated in key cellular processes, including numerous pathways that control senescence. Indeed, many microRNAs show altered expression levels during senescence. A notable class of microRNAs implicated in growth arrest and senescence is the human let-7 family. Given that let-7 members are expressed from genomic regions that are deleted in tumors and that they suppress expression of oncogenes and proteins that enhance cell proliferation, the let-7 family has been implicated in tumor suppression. Conversely, let-7 members have been proposed to promote senescence, as their levels rise during cell senescence and let-7 suppresses the production of proteins that promote proliferation and inhibit senescence.

Circular RNAs (circRNAs) are ncRNAs that form covalently closed circles. Initially, they were considered byproducts of splicing, but recent work has revealed that a vast number of circRNAs exist in mammalian cells and that some of them are abundant and stable, suggesting that they may have regulatory functions in the cell. A substantial fraction of spliced transcripts gives rise to circRNAs, but the repertoire of transcripts from which circRNAs are derived is cell type-specific, supporting the notion that circRNA biogenesis and function may be highly regulated. CircRNAs are believed to influence several cellular processes. CircRNAs have been known for more than two decades but did not draw much attention until recently, when their high abundance was revealed by transcriptome-wide RNA-sequencing and several circRNAs have been characterized as inhibitors of microRNAs and thus regulators of gene expression.

Here, we used high-throughput RNA sequencing (RNA-Seq) to survey senescence-associated circRNAs (which we termed 'SAC-RNAs') differentially expressed in proliferating and in senescent human fibroblasts. Among the circRNAs selectively reduced in senescent cells, we focused on CircPVT1, as silencing CircPVT1 in proliferating cells triggered senescence. Although several microRNAs were predicted to bind CircPVT1, only let-7 was found enriched after pulldown of endogenous CircPVT1, suggesting that CircPVT1 might selectively modulate let-7 activity and hence expression of let-7-regulated mRNAs. Reporter analysis revealed that CircPVT1 decreased the cellular pool of available let-7, and antagonizing endogenous let-7 triggered cell proliferation. Importantly, silencing CircPVT1 promoted cell senescence and reversed the proliferative phenotype observed after let-7 function was impaired. Consequently, the levels of several proliferative proteins that prevent senescence, such as IGF2BP1, KRAS and HMGA2, encoded by let-7 target mRNAs, were reduced by silencing CircPVT1. Our findings indicate that the SAC-RNA CircPVT1, elevated in dividing cells and reduced in senescent cells, sequesters let-7 to enable a proliferative phenotype.

A Summary of the NIA Interventions Testing Program

The NIA Interventions Testing Program (ITP) is a fairly old-school effort to rigorously test all the plausible claims of modestly slowed aging in mice via pharmaceuticals, dietary supplements, and environmental factors like calorie restriction. For those of us more interested in outright rejuvenation through damage repair after the SENS model, rather than merely slowing aging a little, I think there still a number of things worth learning from the ITP results to date. For example, firstly, that almost all claims of slowed aging in mice due to supplements and drugs made in past years were artifacts or otherwise erroneous results, and vanish when evaluated with greater rigor. That suggests that any result of around 10% life extension in mice should probably be taken with a grain of salt, given that the ITP researchers have observed variance in the life spans of control mice raised in identical environments at different study sites. Secondly, that it is very hard to evaluate small differences in aging and life span. This is a part of the larger point I try to make on efforts to slow aging: that for a number of reasons it is more expensive and more challenging than attempts to produce rejuvenation by reverting the established differences between old and young tissues, such as accumulations of metabolic waste, senescent cells, and other forms of molecular damage. Rejuvenation therapies, when they work, should reliably result in larger differences in life span - there should be absolutely no ambiguity at all about the outcome.

The Interventions Testing Program (ITP) was established by the National Institute on Aging (NIA) to investigate the potential of dietary interventions to promote healthy aging. The ITP uses a four-way cross genetically heterogeneous mouse model (UM-HET3) to reduce the impact of strain-specific characteristics on outcomes. Lifespan tests are done in parallel, using the same protocol, at three independent sites to increase robustness of the findings. Population sizes are large enough that the protocol will detect a 10% change in mean lifespan, in either sex, with 80% power, pooling data from as few as two sites. Standard operating procedures were designed to maintain as much consistency as possible among the three sites, including caging, bedding, food, and light/dark cycles. Interventions for testing are proposed by the research community through an annual call-for-proposals, and proposed compounds have ranged from drugs and dietary supplements to micronutrients and metabolic intermediates.

Before the ITP embarks on testing a compound, pilot studies are done to maximize the chances of a successful test. Goals of the pilot studies include demonstrating that the compound is stable in food and that it is uniformly mixed in the food, determining blood levels after short-term treatment (bioavailability), showing evidence of an effect from the short-term treatment (bioactivity), and in some cases, testing for toxicity. The testing of rapamycin is a good case-in-point for analyzing stability of the compound in the food. Pilot analysis showed that about 85% of the rapamycin was degraded by the food preparation process, leading to the use of microencapsulation to deliver stable doses of the compound in food.

The list of all compounds tested by the ITP and in progress is on the ITP website. To date, six compounds have shown significant extension of lifespan: aspirin in males only; rapamycin in males and females (with a greater effect in females); 17αEstradiol in males only; acarbose in males and females (with a greater effect in males); nordihydroguaiaretic acid (NDGA) in males only, and protandim in males only. The positive findings illustrate some important aspects for aging interventions research. The effective interventions appear to include several disparate mechanisms, demonstrating that many cellular pathways might be exploited to influence lifespan and aging. Rapamycin modulates the nutrient-sensing pathways via its interaction with mTOR. Acarbose was anticipated to work as a caloric restriction mimetic due to its ability to reduce the rate of absorption of carbohydrates, but its mechanism of action appears more complex, since caloric restriction results in significant lifespan extension in both male and female UM-HET3 mice, while the effects of acarbose were much larger in males. Aspirin is known for its anti-inflammatory and antioxidant activities, NDGA also has anti-inflammatory and antioxidant activities, 17αEstradiol has neuro-protective properties independent of binding to the estrogen receptor, and protandim activates Nrf2 transcriptional regulator. This diverse group of interventions demonstrates the complex nature of the biology of aging.

Another major surprise is the extent of sex differences in response to the interventions. Four of the six positive interventions only worked in one sex, and the two that had an effect in both sexes showed sex-specific differences in the extent of the effect. Blood levels of a compound sometimes differed between males and females, but that did not always explain the sex difference in lifespan extension. For rapamycin, achieving approximately equivalent blood levels in males and females by treating with different doses did result in similar increases in lifespan. But for NDGA, even at doses giving similar blood levels in males and females, females still did not respond. The ITP's findings illustrate how important it is to examine the effects of interventions in both sexes and suggest that further studies on the mechanism of these sex effects may yield important insights into the underlying biology, and guidance for eventually clinical studies. Multi-site testing protocols also add value to the design because some site-to-site variation is unavoidable even with every effort made to minimize differences between sites. For example, the ITP has consistently found that control male mice at one site weigh less and live longer than the control males at the other two sites, even though each site uses the same food preparations and standardized husbandry. Positive findings replicated in different labs are inherently stronger than a finding from one lab, while disparate findings convey a valuable caution and emphasize the need for replications in other laboratories, other mouse stocks, and other drug doses.

Link: http://www.ebiomedicine.com/article/S2352-3964(16)30554-0/fulltext

Initial Results Reported from a Phase 1 Safety Trial of a Tau Vaccine

Alzheimer's disease is both an amyloidosis and a tauopathy; its symptoms are produced by some combination of the presence of solid deposits of misfolded amyloid-β and tau protein, though there is much debate over which is more important and how they interact with one another and brain cells in order to produce pathology. Effective treatment will probably involve removing both amyloid-β and tau aggregates from brain tissue and cerebrospinal fluid. So far the best class of approach, and the one with the most funding behind it at the present, is immunotherapy, engineering the immune system to attack and remove the unwanted waste. Even that has proven to be much harder than expected, however, and the field is littered with failed trials and promising implementations that did not translate from animal studies to human biochemistry. Only recently have human trials produced meaningful results in amyloid clearance, and earnest efforts to remove tau from the brain started later and have less funding. Still, there is progress towards immunotherapies that can clear tau, as noted here:

So far, many of the antibody drugs proposed to treat Alzheimer's disease target only the amyloid plaques. Despite the latest clinical trial that is hailed as our best chance in the quest for treating Alzheimer's, all later phase trials have failed with many causing severe side effects in the patients, such as abnormal accumulation of fluid and inflammation in the brain. One of the reasons for side effects, many speculate, is due to the antibody directing a reaction towards normal amyloid present in blood vessels or simply releasing beta-amyloid caught in the vessel wall.

The authors of the study have developed a vaccine that stimulates the production of an antibody that specifically targets pathological tau, discovering its "Achilles' heel". It is able to do this because healthy tau undergoes a series of changes to its structure forming a new region that the antibody attacks. This new region (the "Achilles' heel"), while not present in healthy tau, is present in diseased tau early on. Therefore, the antibody tackles all the different varieties of pathological tau. In addition to this important specificity, the antibody is coupled to a carrier molecule that generates a considerable immune response with the added benefit that it is not present in humans, thus avoiding the development of an immune reaction towards the body itself.

Side effects have included a local reaction at the site of injection. This skin reaction is thought to occur due to the aluminum hydroxide, an adjuvant used in vaccines to enhance the body's own antibody production. No other serious secondary effects were directly related to the vaccine. Overall, the safety of the drug and its ability to elicit an immune response were remarkable. While many trials against Alzheimer's disease stubbornly continue to target amyloid, our study dares to attack the disease from another standpoint. This is the first active vaccination to harness the body's ability to produce antibodies against pathological tau. Even though this study is only a phase 1 trial, its success so far gives the authors confidence that it may be the answer they are looking for to halt the progress of this devastating disease.

Link: https://www.eurekalert.org/pub_releases/2016-12/ki-tfc121216.php

In the Last Three Weeks of the SENS Rejuvenation Research Fundraiser, Donations are Tripled by Matching Until the End of the Year

This year's SENS rejuvenation research fundraiser has three weeks to go, and there are now two challenge funds with money left to match your charitable donations: the $150,000 fund established by Michael Greve's Forever Healthy Foundation, and today Josh Triplett has added another $20,000 above and beyond his generous donations earlier in the year. Thus donations to the SENS Research Foundation made now will be matched twice. Give $100 and a total of $300 will go towards expanding the SENS research programs aimed at bringing an end to age-related disease, frailty, and mortality, an end to the suffering and pain that accompanies aging today. In addition there are still matching dollars left to encourage people to become SENS Patrons. Sign up as a monthly donor to the SENS Research Foundation before December 31st, and Josh Triplett, Christophe and Dominique Cornuejols, and Fight Aging! will match the next year of your donations. If you know someone who hasn't yet decided on the charity he or she will support this year, then point out the good work of the SENS Research Foundation.

As 2016 winds to a close, drawing a line under a tremendous amount of progress towards the first viable rejuvenation therapies based on clearance of senescent cells, I encourage you to reread the SENS materials and the overview of the research programs that the SENS Research Foundation has organized and funded using years of donations from people like you and I. Consider for a moment how fortunate we are to live in an age in which we have the opportunity to help make the end of aging a reality. That there is a good enough understanding of the biochemistry of old tissues to identify the metabolic wastes, the cross-links in the extracellular matrix, the damage to mitochondrial DNA, the senescent cells, and other causes of aging. Further, that biotechnology is moving rapidly enough for the therapies repair and reverse these root causes of aging to be plausible and achievable. That observers such as I can assemble forecasts based on present ongoing work in the scientific and biotechnology communities and order the likely near future clinical availability of various approaches to human rejuvenation. All that remains is to persuade people and to raise the funds needed to make it happen, and in that we are so very much further ahead than we were even a decade ago.

Yet there is so very much left to accomplish! From here it might seem a mountain of work, to go from a world in which next to nothing can be done about aging to a world in which aging is controlled and defeated, but in reality small differences today are all that lie between (a) a future in which aging is, by increments, brought under medical control soon enough to save our lives and those of our children and (b) a future in which aging continues to destroy the lives of everyone. These small differences are the choices made by a handful of people today, choices that will snowball in the years ahead to create significant change: the choices made by researchers, advocates, and everyday philanthropists. If you are one of the modest community whose members read Fight Aging! from time to time, then you are one of those people, knowing enough and seeing far enough ahead to understand that the world can be changed for the better. That aging is not set in stone, and its causes can be repaired. All great and sweeping change starts small, with a few small decisions: the decision to tell a friend about the SENS Research Foundation and the likely prospects for the future; the decision to donate as you can to help the research take place; the decision to learn more about the underlying science.

A golden future lies ahead of us, if we just reach for it. So donate to the SENS Research Foundation, an organization doing a great deal to create that future, removing roadblocks from research and development, and giving rise to serious commercial efforts to produce cost-effective, widely available rejuvenation therapies.

Evidence for Exercise to Improve Mitochondrial DNA Repair via p53 Activity

To add to the list of possible mechanisms by which exercise improves long-term health, researchers here offer evidence for exercise to enhance repair of damage to mitochondrial DNA. Note that they are using mice with a DNA repair deficiency that exhibit accelerated development of age-related disease, and this is often a path to results that have little bearing on normal aging, but in this case I don't think that greatly impacts the principal finding of a evidence for a novel mitochondrial DNA repair mechanism triggered by exercise. The herd of hundreds of mitochondria found in every cell are the remnants of symbiotic bacteria, with many important roles in cellular biochemistry. They still replicate like bacteria and carry their own DNA. Unfortunately that DNA is more prone to damage and less readily repaired than the DNA in the cell nucleus. Some forms of damage, such as deletions that impair the mitochondrial processes that produce the energy store molecule ATP, lead to mitochondria that are both dysfunctional and able to replicate more effectively than their peers. Cells become taken over by these broken mitochondria and fall into a state in which they export harmful, reactive molecules into the surrounding tissues. This process contributes to degenerative aging. Therefore any mechanism that improves mitochondrial DNA repair is likely to slow the impact of aging, and we might expect to find such mechanisms involved in at least some of the known methods of modestly slowing aging in laboratory species.

Molecular investigations of age-related pathologies implicate mitochondrial DNA (mtDNA) mutations as one of the primary instigators driving multisystem degeneration, stress intolerance, and energy deficits. It is intuitive to assume that the de novo mtDNA mutations observed during aging are due to accumulated, unrepaired oxidative damage, but some evidence actually suggests that mtDNA replication errors may be the more important culprit. The demonstration that multiple aspects of aging are accelerated in mutator mice harboring error-prone mitochondrial polymerase gamma (POLG1) provides support for the causal role of mtDNA replication errors in instigating mammalian aging.

The epidemic emergence of modern chronic diseases largely stems from the adoption of a sedentary lifestyle and excess energy intake. There is incontrovertible evidence that endurance exercise extends life expectancy and reduces the risk of chronic diseases in both rodents and humans. We have previously shown that endurance exercise effectively rescued progeroid aging in mutator mice concomitant with a reduction in mtDNA mutations, despite an inherent defect in POLG1 proofreading function. Exercise has also been shown to increase telomerase activity and reduce senescence markers. These findings suggest a link between exercise-mediated metabolic adaptations and genomic (nuclear and mitochondrial) stability; however, the identity of this metabolic link remains unknown. In this study, we have utilized PolG mice to investigate the mitochondrial-telomere dysfunction axis in the context of progeroid aging, and to elucidate how exercise counteracts mitochondrial dysfunction and mtDNA mutation burden through mitochondrial localization of the tumor suppressor protein p53.

Endurance exercise reduces mtDNA mutation burden, alleviates multisystem pathology, and increases lifespan of the mutator mice, with proofreading deficient POLG1. We report evidence for a POLG1-independent mtDNA repair pathway mediated by exercise, a surprising notion as POLG1 is canonically considered to be the sole mtDNA repair enzyme. Here, we show that the tumor suppressor protein p53 translocates to mitochondria and facilitates mtDNA mutation repair and mitochondrial biogenesis in response to endurance exercise. Indeed, in mutator mice with muscle-specific deletion of p53, exercise failed to prevent mtDNA mutations, induce mitochondrial biogenesis, preserve mitochondrial morphology, reverse sarcopenia, or mitigate premature mortality. Our data establish a new role for p53 in exercise-mediated maintenance of the mtDNA genome and present mitochondrially targeted p53 as a novel therapeutic modality for diseases of mitochondrial etiology.

Link: http://dx.doi.org/10.1186/s13395-016-0075-9

Proposing Cross-Linking in the Extracellular Matrix to Contribute to Immunosenescence

In this interesting open access paper, the authors propose that too little attention has been given to immune cell behavior in tissues rather than in blood, and that means that researchers have overlooked the possibility that age-related changes in the extracellular matrix structures that support tissues might be a significant cause of the growing immune dysfunction that takes place in later life. One of the more important of these changes in the extracellular matrix is the growing presence of cross-links, persistent sugary compounds produced as a byproduct of normal metabolic operations that chain together the large molecules of the extracellular matrix. In doing so these cross-links change the chemical and structural properties of the matrix and the tissue as a whole, producing results such as loss of elasticity in skin and blood vessels, which in turn contribute to a variety of age-related diseases. If cross-linking does indeed contribute to immunosenescence, the decline of the immune system with age, then that only increases the importance of ongoing research funded by the SENS Research Foundation aimed at safely breaking down this unwanted form of metabolic waste. In humans near all persistent cross-links appear to involve a single class of compound, glucosepane. So in theory there is only a single target here, needing just one drug development program to make a large difference to long-term health and longevity.

Immunosenescence is defined as age-related changes in the immune system. It is associated with a progressive deterioration of the ability to mount immune responses and with a higher mortality rate in the elderly. Immunosenescence is currently thought to depend on lifelong antigen load, leading to the senescence of cells in the immune compartment, with a prominent role attributed to the chronic anti-cytomegalovirus (anti-CMV) response. There seems to be an increasing use of immune resources allocated to the anti-CMV response with aging, a process that ultimately leads to exhaustion. The cause remains unclear and in humans the few studies examining the presence of viral reactivation in the blood, found it negative. More data are therefore needed in the field of human aging in order to conclude on this point. The role of CMV in immunosenescence is clearly important, but, rather than being directly causal, can also be interpreted as a consequence of more general age-related changes in the three-dimensional microenvironment in which most immune cells are mobile and operate, the extracellular matrix (ECM). Immunologists have neglected the implications of such changes, partly because most of the studies carried out on immunosenescence, at least until very recently, focused on blood because it is the most accessible source of cells and biological fluid in humans. Although of value, these data, lead to an overestimated qualitative and quantitative importance of this compartment in the understanding of the immune system physiology. The recent discovery of resident memory T cells, or TRM, showed immune surveillance to be largely local and, therefore, not readily accessible through studies on blood.

Here, we argue that efforts to decipher immunosenescence must consider both blood and the ECM. The TRM are located in the ECM, and the known biochemical and biophysical modifications to this medium associated with aging consequently hampers local immune surveillance by these cells. ECM proteins and proteoglycans have well-documented roles in scaffolding, but they also have a profound effect on cell behavior, through interactions with secreted ligands or cell-transmembrane receptors, in particular integrins. We suggest that the progressive and irreversible age-related changes in the extracellular matrix may actually provide a unifying framework explaining all the molecular and cellular features of immunosenescence. The key point is that for the immune cells to be functional, they must be free to recirculate, navigate and rest within the extracellular matrix, in tissues and organs. This point is instrumental in tissue surveillance and protection even in the absence of peripheral lymphocytes. We will consider immunosenescence within this framework, focusing on the adaptive immune system and T cells in particular, even though these cells are neither the only ones to be affected during aging nor the only ones concerned with mobility.

We argue that the mobility of immune cells in non-lymphoid tissues is a necessary element for effective immunity. A lack of immune cell mobility, either intrinsic, as in hereditary defects affecting actin remodeling for example, or extrinsic, as in aging, results in an impairment of immune responses. No three-dimensional (3D) model of deregulated cell mobility has ever been proposed or explored in the context of immunosenescence. We hope that this hypothesis which is based on reviews of fields that have not hitherto be connected together will promote future studies, in silico and in vitro, to validate this theory experimentally. The 3D model can reconcile many features of aging, such as the altered responses to vaccination, which is in essence both a memory and a local process, and dysfunctions of peripheral tolerance (autoimmunity). The chronic process of T cell death due to mechanical stress within the cross-linked mesh of the aged ECM may also account for activation of the inflammasome, leading to inflammaging, and to a state of immune deficiency typical of aged subjects. In conclusion, we propose an update of the theoretical framework of immunosenescence, based on a novel hypothesis: the increasing stiffness and cross-linking of the senescent ECM lead to a progressive immunodeficiency due to an age-related decrease in T cell mobility and eventually the death of these cells. A key element of this mechanism is the mechanical stress to which the cell cytoplasm and nucleus are subjected during passage through the ECM.

Link: http://dx.doi.org/10.1016/j.arr.2016.11.005

An Interview with Mantas Matjusaitis of CellAge, Crowdfunding New Senescent Cell Markers and Removal Methodologies

I mentioned CellAge some weeks ago; a new entry to the collection of companies and research groups interested in developing the means to safely identify and remove senescent cells from old tissues. A few days later one of those companies, UNITY Biotechnology, announced a sizable $116 million venture round, which certainly put the field on the map for anyone who wasn't paying attention up until that point. In contrast, CellAge are taking a less commercial path for now, by raising funds from the broader community of supporters and intending to make some of the tools they create freely available to the field. Why are senescent cells important? Because they are a cause of aging, and removing them is a narrowly focused form of rejuvenation, shown to restore function and extend healthy life in animal studies. An increasing number of senescent cells linger in our bodies as we age, secreting signals that harm tissue structures, produce chronic inflammation, and alter the behavior of nearby cells for the worse. Senescent cells also participate more directly in some disease processes, such as the growth of fatty deposits, weakening and blocking blood vessels, that takes place in atherosclerosis. By the time that senescent cells come to make up 1% of the cell population in an organ, their presence causes noticeable dysfunction and contributes significantly to the progression of all of the common age-related diseases.

This coming Monday, the CellAge team will be hosting an /r/futurology AMA event - the post is up already if you want add your own questions for the scientists involved. Earlier this week, the CellAge principals launched a crowdfunding campaign with Lifespan.io: they are seeking $40,000 with stretch goals and rewards beyond that to get started on their vision for senescent cell therapies. If you've ever wanted the chance to have a DNA promoter sequence named after you ... well, here it is. This has certainly been a busy year for community fundraising in rejuvenation research: I imagine that things will heat up even more in the years ahead. The CellAge view of the field of senescent cell clearance is that the markers currently used to identify senescent cells are too crude and lacking in specificity. These researchers want to build the basis for the next generation of better senescent clearance therapies, those capable of identifying and removing far greater proportions of these unwanted cells. This is an admirable goal, given that those involved intend to make the initial results of their work freely available to to the research community. From my point of view, I'd say the current markers are absolutely good enough for a first pass, the production of a therapy that will produce significant benefits, and the results in mice and rats achieved over the past two years are an adequate demonstration on that front. I'm definitely in agreement that research and development doesn't stop at "good enough for a first pass," however. There should always be someone building the next and better generation of medicine around the time that the current generation is heading towards the clinic. So take a look at this fundraiser and see what you think; the technical details make for interesting reading.

CellAge: Targeting Senescent Cells with Synthetic Biology

Recently it has been demonstrated that senescent cells (cells which have ceased to replicate due to stress or replicative capacity exhaustion) are linked to many age-related diseases. Furthermore, removing senescent cells from mice has been recently shown to drastically increase mouse healthspan, the period of life free of serious diseases. CellAge, together with a leading synthetic biology partner, Synpromics, are poised to develop a technology allowing for the identification and removal of harmful senescent cells. Our breakthrough technology will benefit both the scientific community and the general public.

In short, CellAge is going to develop synthetic promoters which are specific to senescent cells, as promoters that are currently being used to track senescent cells are simply not good enough to be used in therapies. The most prominently used p16 gene promoter has a number of limitations, for example. First, it is involved in cell cycle regulation, which poses a danger in targeting cells which are not diving but not senescent either, such as quiescent stem cells. Second, organism-wide administration of gene therapy might at present be too dangerous. This means senescent cells only in specific organs might need to be targeted and p16 promoter does not provide this level of specificity. Third, the p16 promoter is not active in all senescent cells. Thus, after therapies utilizing this promoter, a proportion of senescent cells would still remain. Moreover, the p16 promoter is relatively large (2.1kb), making it difficult to incorporate in present gene therapy vehicles. Lastly, to achieve the intended therapeutic effect the strength of p16 promoter to drive therapeutic effect might not be high enough.

CellAge will be constructing a synthetic promoter which has a potential to overcome all of the mentioned limitations. A number of gene therapy companies have successfully targeted other types of cells using this technology. With your help, we will be able to use same technology to develop tools and therapies for accurate senescent cell targeting. As our primary mission is to expand the interface between synthetic biology and aging research as well as drive translational research forward, we will offer our senescence reporter assay to academics for free. We predict that in the very near future this assay will be also used as a quality control step in the cell therapy manufacturing process to make cell therapies safer!

I recently had the chance to talk with the CellAge founder Mantas Matjusaitis about the initiative and his views of the broader field. After so many years of bootstrapping support for senescent cell research, it is definitely very welcome to see such an influx of interest in senescent cell therapies, and the arrival of many diverse approaches in this area of research and development.

How did you folk at CellAge meet? What made you decide that senescent cell clearance was the most needful accomplishment you could work on?

As many worthwhile efforts go, we didn't push CellAge into existence just because we wanted to start a company. I have been following ageing research for very long time and so I was aware what is happening in the field. At the same time, I emerged myself into synthetic biology where I am doing my PhD now. For a while, I have been exposed to these different fields and at some point things just connected. Recent publications on mouse models showed that there is a great promise in removing senescent cells and from my own end, some exciting technological opportunities presented themselves from the synthetic biology side. So CellAge is really a result of many coincidence that led to this project. After I discussed these ideas with more experienced people, some of whom are our advisors now, I came to realize that there is a real opportunity here and we took it!

There are a lot of approaches under development; perhaps you could outline yours and how it differs from those of Oisin, UNITY, and SIWA, among others?

Yes there are multiple companies working towards same or similar goal and I am very happy of their efforts. First and foremost, I am scientists and I lead CellAge as a scientist - we just want to see this technology coming to existence, be it us or someone else who does it. That being said, at this stage it's really hard to see which approach will be best and it's likely (considering examples in oncology field) that combination of therapies will need to be taken (e.g. immunotherapy together with gene therapy or small molecules together with gene therapy). Moreover, some approaches might be more suitable for some applications and some patient groups. So its good we have multiple shots at the same goal to maximize our success chances and not have all the eggs in the same basket. But of course this all only make sense if we have an unique angle and I strongly believe we do! At CellAge, we are focusing on using synthetic biology tools to construct promoters which will be only active in senescent cells. Early on, this will help scientists working on aging research to better identify senescent cells and push field forward faster, and later this might become a key or supportive technology used in the therapies. Lastly and most importantly, I just want to stress out that for me science is key thing here and I do not see other groups working the the field as competition but rather as a potential source of collaboration.

There seems to be a growing contingent who want to treat cellular senescence by tinkering with or shutting down the senescence-associated secretory phenotype (SASP). What is your take on this as an approach versus cell destruction?

I think this is a very potent strategy, which probably is also technically easier to achieve because of regulatory burdens and the fact that small molecules might be more potent in this front. That being said, there might be couple of downsides with this approach and so different approaches, like ours at CellAge, should still be investigated. Firstly, different cells have different SASP and so there might not be a single bullet to cure it all. Secondly, although SASP is one of the key mechanisms how senescent cells harm our body but it's not the only one. Senescent cells can also escape senescence and become cancerous. Lastly, unless you take "SASP inhibitors" for the rest of your life, this will be only temporary solution if cells remain in the tissues. Also, I just would like to add that senescent cell destruction is only a first step for us. Here at CellAge we believe that eventually we will go beyond just killing cells and will be able to repair cells before they become damaged or senescent.

You're looking at crowdfunding; what made you choose this path for the initial development of your work?

Crowdfunding is not the only path we are taking, but it is one we are counting on most. We are also applying for grants and various competitions in addition to this crowdfunding campaign. We believe that for the stage of our company, this is most appropriate path. Importantly, we want to make our tools available to academics free of charge and investors might have a problem with that.

You are clearly energized by the goal of healthy life extension, making the human life span longer. What is your vision for the broader future of SENS-like rejuvenation medicine over the coming decades?

As a scientists I would like to be a bit more skeptic and rather advocate that CellAge is working on healthspan, rather than lifespan extension. I think that although we had glimpses of how lifespan can be expanded in mice, but we are still relatively far from translating that into humans. Instead, CellAge is focusing on age-related diseases and their prevention - a field in which role of senescent cells has much more of scientific proof. I personally am a big fan of SENS and their work. I think they are taking a correct way forward and I would even dare to predict, or hope, that many things they are aiming to achieve will reach the daylight soon enough. For the future, CellAge vision is to construct even more elaborate genetic circuits and gene therapies which will allow to fix cells instead of killing them. We are big believers in using biological logical gates and circuits to construct novel computing processes in the cells in the form of gene therapy.

Applying More Rigor to the Search for Drug Candidates to Modestly Slow Aging

The majority of researchers interested in treating aging as a medical condition are involved in work that will, at best, only modestly slow the progression of age-related disease and dysfunction. They do not follow the SENS view of damage repair to produce rejuvenation, but rather the idea that one must alter the operation of metabolism in order to slow down the pace at which damage occurs. The scope of the possible benefits is much smaller via this approach, and further it is probably more expensive to achieve those lesser results. Altering metabolism safely requires a greater level of understanding than repairing the existing and well-understood forms of damage that produce aging, and generating that understanding is slow and expensive. You might look back at the past decade of work on sirtuins, for example, one tiny slice of the biochemistry associated with calorie restriction: a very large amount of time and money has gone into improving knowledge of that area of metabolism, but there is nothing of practical use to show for it as a result. Some research groups respond to this history with efforts to improve the process of drug development, to move towards more cost-effective ways to both analyze the vast mountains of existing data on metabolism and identify drug candidates that will produce the desired modest slowing of the aging process. Here is an example of the type:

Researchers have developed the GeroScope algorithm to identify geroprotectors - substances that extend healthy life. Hundreds of compounds were screened for geroprotective activity using computer simulations, and laboratory experiments were conducted on the ten substances that were identified using this algorithm. Decades of hard work by highly-competent research teams and millions of dollars are spent on the process of developing new drugs. And the screening and development process of geroprotectors, interventions intended to combat aging, a complex multifactorial biological process affecting every cell in the human body, is even more tedious. Computer modeling techniques may significantly reduce the time and cost of development. "The aging of the population is a global problem. Developing effective approaches for creating geroprotectors and validating them for use in the human body is one of the most important challenges for biomedicine. We have proposed a possible approach that brings us one step closer to solving this problem."

For several years the group studied cancer-related processes and relied on the Oncofinder, an algorithm designed to study and analyze the activation values of molecular pathways by comparing gene expression in cancerous and normal healthy cells, and also comparing tissue samples of different patients. The researchers applied a similar approach to develop GeroScope, which is able to compare changes in the cells of young and old patients and search for drugs with minimal side effects that compensate for these changes. To do this, the scientists analyzed transcriptomic data in "young" (donors aged between 15 and 30 years) and "old" (donors over the age of 60) samples from many human tissue types. This data was used for advanced computer modeling to identify and re-construct the molecular pathways associated with aging. Molecular pathways are a sequence of reactions that lead to changes in a cell. The most common molecular pathways are involved in metabolism and signal transduction. GeroScope modeled molecular pathways and analyzed cell reactions to various substances. Having chosen 70 compounds from the database of geroprotective drugs, the scientists used the new algorithm to identify 10 substances that could have geroprotector properties in accordance with the model.

The predictions made by the computer model were confirmed in cell cultures of human fibroblasts for several substances. Some of these drugs are already actively sold as dietary supplements individually. Further analysis of the pathway-level effects of many of these compounds provided insights into the possible combinations providing maximal cumulative effects and minimizing the possible adverse effects. "For computer modeling this is a very good result. In the pharmaceutical industry, 92% of drugs that are tested on animals fail during clinical trials in humans. The ability to simulate biological effects with such a high level of accuracy in silico is a real breakthrough. We hope that some of these drugs will soon be tested on people using biologically-relevant biomarkers of aging."

Link: https://mipt.ru/english/news/geroscope_a_computer_method_to_beat_aging

Exercise Improves Arterial Resilience to Age-Related Increases in Oxidative Stress

Researchers digging deeper into the mechanisms by which exercise produces benefits have found that it improves the resistance of blood vessels to oxidative stress. With age the presence of oxidizing molecules and oxidative modification of proteins, preventing correct function, increases for reasons that include damage to mitochondria, the power plants of the cell. Oxidative damage to molecular machinery is somewhere in the middle of the chain of cause and effect that starts with fundamental forms of damage to cells and tissues and spirals down into age-related diseases. Near all of this oxidation is repaired very quickly, the damaged molecules dismantled and recycled, but in most contexts more of it over the long term is worse than less of it.

Cardiovascular diseases (CVD) are the leading cause of death in developed societies. The risk of CVD increases progressively with advancing age, such that greater than 90% of deaths from CVD occur in people over the age of 55. Although the mechanisms underlying the age-related increase in CVD risk have not been fully elucidated, strong evidence indicates that the development of arterial dysfunction is a key factor. An important manifestation of arterial dysfunction is vascular endothelial dysfunction, characterized by a decline in endothelium-dependent dilation (EDD).

A major mechanism underlying the development of age-related endothelial dysfunction is oxidative stress, characterized by excessive production of reactive oxygen species (ROS) relative to endogenous antioxidant defense capacity. Oxidative stress can disrupt many aspects of arterial function, including reducing the bioavailability of the vasodilatory and vasoprotective molecule nitric oxide (NO), resulting in impaired EDD. A key source of arterial oxidative stress is excessive production of mitochondrial reactive oxygen species (mtROS). Whereas healthy mitochondria are critical mediators of arterial homeostasis and produce physiological levels of mtROS vital for cell signaling, declines in mitochondrial health are characterized by excessive mtROS production. We have recently shown that excess arterial mtROS production is a major contributor to tonic arterial oxidative stress-mediated suppression of EDD with primary aging in mice. Emerging evidence suggests that, in addition to baseline deficits in vascular function, aging may also be accompanied by reduced arterial resilience, i.e., the ability to withstand stress. Because human aging occurs in the presence of numerous stressors, it is important to understand how aging alters arterial resilience and to identify potential interventions that may improve the ability of arteries to withstand these challenges.

Mitochondria are critical components of the cellular stress response and interact with and regulate other stress response mediators, including antioxidant enzymes and heat shock proteins (Hsp). Thus, mitochondrial dysregulation has the potential to impact major upstream mechanisms, such as oxidative stress, that mediate vascular function. However, it is unknown whether age-related declines in arterial mitochondrial health contribute to decreased resilience in the presence of acute stressors. Aerobic exercise is a powerful intervention that improves baseline endothelial function in the setting of aging. It is well known that aerobic exercise improves mitochondrial biogenesis and homeostasis in non-vascular tissues, and recent work suggests that exercise can also improve markers of arterial mitochondrial content and health in healthy animals, but the effects of aerobic exercise on arterial mitochondria with primary aging are unclear. We tested the hypothesis that aging would be associated with impaired arterial resilience to acute stress and reduced arterial mitochondrial health in mice, and that voluntary aerobic exercise initiated in late-life (10 weeks of voluntary wheel running) would increase resilience and improve mitochondrial health in aging arteries.

In line with a recent study in our laboratory, we observed that age-related vascular endothelial dysfunction is accompanied by elevated arterial mitochondrial superoxide production. Importantly, we show here that voluntary aerobic exercise normalized mitochondrial superoxide production in arteries of old mice, suggesting that exercise-induced reductions in arterial mitochondrial oxidative stress may contribute to improvements in vascular endothelial function. Our findings further extend previous work by demonstrating that, in addition to restoring baseline vascular endothelial function, voluntary aerobic exercise improves arterial resilience to acute stressors in old mice. Consistent with our previous report, we observed that acute treatment with rotenone, a mitochondrial Complex I inhibitor that can also induce mitochondrial superoxide production, impairs carotid artery endothelial function in old mice to a greater degree than arteries from young mice, indicating that aging arteries are more vulnerable to a mitochondria-specific challenge. In the present study, we show that voluntary aerobic exercise completely restores the ability of aged arteries to withstand this acute mitochondrial stress.

Link: http://dx.doi.org/10.18632/aging.101099

Recent Research on Modulating Muscle Stem Cell Decline with Aging

Today I'll point out a couple of recent papers that are illustrative of present research into muscle stem cells and the changes that take place in these cell populations with age. Note the interest in finding ways to modulate those changes, slow them down, or somewhat reverse them. Muscle stem cells are one of the most studied of stem cell populations, a state of affairs that is partly historical accident and partly because it is easier to obtain cells to work with that is the case for many other tissues. There are hundreds of cell types in the body, and every different form of tissue is supported by its own populations of stem cells and progenitor cells at various stages of differentiation. They are all very different, requiring different signals and circumstances in order to function correctly, as is illustrated by the fact that researchers need to develop new methodologies to work with each new tissue type that is built from cells in the laboratory. Understanding muscle stem cells is just one step on a lengthy road leading towards a complete catalog of the cellular biochemistry of tissue maintenance and regeneration.

All of our tissues are almost entirely composed of somatic cells with limited replicative lifespans. Once they reach the Hayflick limit, they self-destruct or become senescent, and most of the latter are destroyed by the immune system. Stem cells and progenitor cell populations are less limited but more tightly regulated, spending much of their time dormant. When active they work to create a supply of new somatic cells to replace those lost over time. This system in which near all cells are very limited in growth potential came into being because it enables multicellular organisms to have a low enough rate of cancer to prosper in the evolutionary competition for survival. Cancer and regeneration have always been the opposing sides of the same coin for higher species characterized by important, delicate structures that must be maintained intact over time. Exceptional regeneration of the sort possessed by hydras, a species that appears to be functionally immortal, gets left behind somewhere before the evolution of a sophisticated central nervous system: it may well be that those two characteristics are mutually exclusive. Still, we mammals got a raw deal in comparison to zebrafish or salamanders, capable of regenerating limbs. At some point it was more favorable in the evolutionary arms race to drop regeneration in favor of additional resistance to cancer.

One of the most pressing aspects of stem cell biology is that the activity of stem cell populations decline with age, something that so far appears to be largely a matter of signaling when it comes to muscle stem cells. That may or may not universally true for other types of stem and progenitor cell. Certainly stem cell populations and their supporting niche cells suffer the molecular damage of aging just like other cells do. Nonetheless, in the case of muscle stem cells there are numerous studies demonstrating restored stem cell activity in old animals via various forms of intervention. Thus there is considerable interest in the research community when it comes to building a map of the biochemistry of this stem cell decline, and then building therapies to put these stem cells back to work. Loss of muscle mass and strength, and ability to regenerate from injury, is an important component of age-related frailty. If that can be reduced by overriding the reactions of cells to rising levels of damage, and without significantly raising the risk of cancer, then perhaps some good can be done here even in advance of methods of repairing the underlying damage that causes aging. I'd much rather see more work on rejuvenation through repair rather than forcing damaged cells into youthful patterns of behavior, but the latter is clearly going to happen regardless of my opinions on the matter: a fair number of research teams are headed in that direction. Stem cell research as a whole is set on a collision course with the issue of stem cell decline in aging, as a sizable majority of the therapies one would want to want to build using stem cell research are for age-related conditions. Solving the issues of failing stem cells in an old tissue environment must happen at some point in order for researchers to achieve their goals.

Muscle PGC-1α modulates satellite cell number and proliferation by remodeling the stem cell niche

Satellite cells (SC) are adult muscle stem cells located at the periphery of muscle fibers. SCs are accordingly exposed to various signals from within and outside of the fiber, which collectively comprise the specific environment termed the SC niche. Although metabolically inactive and quiescent in resting conditions, SCs quickly become activated in response to a stimulus such as injury or strenuous exercise. These stem cells are indispensable for skeletal muscle regeneration, and despite being present in relatively small numbers (2-5% of total myonuclei), SCs have a vast proliferative and regenerative potential. Proper activation and proliferation, as well as return to quiescence, are all essential to preserving SC number and function. In various pathological contexts, for example, in certain muscular dystrophies or aging, a depletion of SC numbers is linked to impaired regenerative capacity. Importantly, reduced SC numbers and myogenic activity are often caused by alterations of the SC niche. For example, excess fibronectin in the basal lamina in an uninjured state is correlated with a reduced ability of SCs to respond to injury. Age-associated accumulation of extracellular matrix (ECM) components leads to the thickening of the basal lamina, thereby preventing SCs from sensing changes in the environment and resulting in a reduced activation propensity. Inversely, treatment with fibronectin can restore satellite cell activation in old muscle. Moreover, local transient fibronectin secretion by SCs is an important step in the cascade of SC activation and subsequent proliferation, and such a transient increase in fibronectin muscle expression is necessary for successful regeneration.

SC numbers vary by muscle fiber type, with higher counts present in oxidative compared to glycolytic muscle beds. In line with this, endurance exercise increases SC numbers in mice and humans. The peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) is a major driver of oxidative fiber-type specification, mitochondrial biogenesis, and high endurance capacity. Furthermore, PGC-1α gene expression is induced by exercise and exhibits a preference for slow, oxidative fibers. Finally, muscle-specific overexpression of PGC-1α protects against a variety of muscle-wasting conditions, including fiber atrophy or the pathologies in dystrophic mouse models. Nevertheless, a potential link between PGC-1α, oxidative fibers, exercise, and SCs has not been studied yet. By using a mouse model which specifically overexpresses PGC-1α in adult muscle fibers, we attempted to delineate the aforementioned missing link and assess the importance of indirect effects of PGC-1α on SC phenotype. Here, we show that muscle fiber PGC-1α modulates SC number as well as proliferation and that the latter, at least in part, could be regulated by the altered expression of ECM components, including fibronectin protein levels, in the basal lamina. Increased PGC-1α content in the SC niche therefore results in an accelerated SC response to injury and higher myogenic capacity.

Loss of niche-satellite cell interactions in syndecan-3 null mice alters muscle progenitor cell homeostasis improving muscle regeneration

During aging, myofiber size progressively decreases with an accompanying loss of fast twitch myofibers, leading to reduced overall muscle mass and strength that, when severe, results in sarcopenia. Loss of muscle mass and strength is accompanied by increased matrix deposition (fibrosis) and increased fat infiltration. Skeletal muscle regeneration is impaired in aged muscle and associated with cell-intrinsic deficits in satellite cell function; however, satellite cell contribution to sarcopenia has been recently questioned, although a contribution of satellite cell loss to aging-associated fibrosis is supported.

Satellite cells in G0 phase reside within the musculature and are poised to rapidly activate in response to injury. Upon activation, satellite cells re-enter the cell cycle, migrate away from their niche, and proliferate as myoblasts, eventually undergoing terminal differentiation into myocytes that fuse into pre-existing damaged muscle fibers or fuse to one another generating new muscle fibers. During regeneration, a portion of satellite cells returns to its niche, re-enters quiescence, and expresses Pax7 but no other myogenic transcription factors. The transmembrane heparan sulfate proteoglycan syndecan-3, a component of the satellite cell niche, controls satellite cell homeostasis by regulating signaling pathways within the niche. Moreover, members of the Syndecan family regulate cell-cell adhesion and cell-matrix adhesion via interaction with integrins and cadherins. Following a muscle injury, syndecan-3 null (Sdc3-/-) satellite cells fail to replenish the resident pool of quiescent satellite cells within the niche and therefore syndecan-3 appears to regulate satellite cell homeostasis.

We show that syndecan-3 loss alters satellite cell adhesion to the myofiber, altering interactions with the niche and (i) improves muscle regeneration upon repeated acute muscle injuries, (ii) rescues muscle histopathology and function in dystrophic muscle tissue, and (iii) improves muscle aging with a reduction in fibrosis. The lifelong improvement in muscle regeneration observed in Sdc3-/- muscle arises in part by altered satellite cell homeostasis and changes in satellite cell adhesiveness to the myofiber.

Age-Related Inflammation and its Effects on the Generation of Immune Cells

With age, the immune system falls into a state of ever increasing chronic inflammation, a process known as inflammaging: the immune system is overactive, but nonetheless declines in effectiveness at the same time. Researchers here consider how inflammaging can damage the bone marrow stem cell populations responsible for generating immune cells, possibly the basis for a vicious cycle in which the failures of the immune system feed upon themselves to accelerate age-related damage and dysfunction.

Hematopoiesis is an active, continuous process involving the production and consumption of mature blood cells that constitute the hemato-lymphoid system. All blood cells arise from a small population of hematopoietic stem cells (HSCs) in the bone marrow (BM) that have two unique properties: self-renewing capacity, the ability to generate themselves, and multi-lineage differentiation capacity, the ability to produce all blood cell types. Since, in the steady state, most adult HSCs are in the G0 phase of the cell cycle, i.e., they are quiescent and are estimated to turnover slowly on a monthly time scale, daily hematopoietic production is mainly sustained by highly proliferative downstream hematopoietic progenitor cells (HPCs).

Aging of the hematopoietic system is represented by functional declines in both the adaptive and the innate immune system, an immunosenescence that leads to high susceptibility to infections, low efficacy of vaccinations, and increased vulnerability to the development of autoimmunity and hematologic malignancies. It has been show that (a) B cell production decreases significantly with advancing age, i.e., the naïve B cell pool diminishes, while the memory B cell pool expands. Diversity of the B cell repertoire also decreases in association with lowered antibody affinity and impaired class switching. B cells are prone to produce auto-antibodies increasing the incidence of spontaneous autoimmunity; (b) de novo T cell production also declines with aging partially due to thymic involution. CD8+ T cells undergo oligoclonal expansion and their repertoire is skewed toward previously encountered antigens, as niches for naïve T cells in peripheral lymphoid tissues become occupied by terminally differentiated cells; (c) NK cells show diminished cytotoxicity and cytokine secretion; (d) although myeloid cells increase in number, their functionality is decreased, e.g., neutrophils migrate less in response to stimuli, and macrophages have reduced phagocytic activity and decreased oxidative burst; and (e) erythropoiesis also declines in elderly people causing frequent anemia, while the thrombocytic lineage has not, to date, been reported to be significantly affected by aging.

There are similarities between hematopoietic alterations during inflammation and those that occur with aging. In response to aging and bacterial infection, myelopoiesis becomes dominant over lymphopoiesis in relation to immunosenescence. Most notably, B-lymphopoiesis is impaired due to a decreased level of E47, a transcription factor essential for B cell development, in aged mice. The aging-associated myeloid dominance and/or adipogenesis in BM might be triggered by increased basal levels of pro-inflammatory cytokines even in the absence of infection. Indeed, levels of circulating pro-inflammatory cytokines, such as IL-6, TNF-α, IL-1Rα, and C-reactive protein, are reportedly upregulated in healthy elderly populations. These observations allow us to hypothesize that "inflammaging" represents a subclinical grade of chronic inflammation possibly contributing to the initiation and/or acceleration of hematopoietic aging.

Since numerous inflammatory factors are increased in aged hematopoietic tissues, and inflammation- and aging-associated hematopoietic changes share common cellular and molecular alterations, it is reasonable to speculate that low-grade inflammation might be involved in hematopoietic aging with reduced fitness of both adaptive and innate immune cells. Given that some hematopoietic phenotypes during inflammation and aging arise from functional alterations in HSCs and progenitor cells (HSPCs), it would be worthwhile to elucidate the underlying common mechanisms. Future research could yield meaningful insights into cell-intrinsic changes in HSPC quantity and quality, e.g., how aspects of HSPC population dynamics such as functional heterogeneity and population size change, whether all subsets of HSCs with a distinct lineage output respond equally to inflammatory stimuli or only the minor fraction is responsive, how the self-renewal and differentiation capacities of HSC are altered on a per-cell basis, and molecular changes in cellular signaling, such as alterations in cellular metabolism, transcriptional networks, epigenetic modifications, and genomic instability. It is also essential to understand to what extent inflammaging-associated cell-extrinsic factors influence HSPC biology, including signals derived from the BM niche, tissue damage/repair, infection, obesity, or the microbiome. In addition, the fundamental task that remains is identification of the factors initially triggering the process of hematopoietic inflammaging. Inflammation- or aging-related external stimuli appear to force quiescent HSCs to proliferate and impair their self-renewal and differentiation capacities, as suggested by evidence that HSC cycling in response to chemotherapy administration or hematopoietic stress accelerates the manifestation of aging phenotypes. These data suggest that the central features of HSCs aging might be attributable to accumulation of a proliferative history that is closely associated with perturbed self-renewal and differentiation.

Inflammation and aging have thus far been seen as two independent pathophysiological processes. However, a growing body of evidence has highlighted biological changes in hematopoiesis and HSCs that are common to both inflammation and aging. Thus, it is likely that sustained inflammatory stimuli contribute to hematopoietic aging and possibly leukemogenesis, supporting the inflammaging concept. Since inflammation and aging might both be involved in increased risk for leukemogenesis, eliminating unwanted inflammaging factors is a potential approach to preserving both HSC and immune functions, and thereby preventing a functional decline in hematopoiesis and the emergence of malignant clones. Future investigation is required to better characterize hematopoietic inflammaging processes at the tissue, cellular, and molecular levels.

Link: http://dx.doi.org/10.3389/fimmu.2016.00502

Immune Function as a Biomarker of Age and Predictor of Remaining Life Expectancy

The immune system declines with age, as the proportion of its cells capable of responding to new threats falls, autoimmunity increases, and the system as a whole enters a state of constant, rising inflammation. The failure of the immune system speeds other forms of damage and dysfunction in aging, as immune cells are responsible for killing potentially harmful cells, such as those that become senescent or precancerous. The immune system also plays important roles in a variety of essential processes, such as wound healing and maintenance of brain tissues. Clearing out the causes of immune system decline will be a necessary part of any future toolkit of rejuvenation therapies. The open access paper linked here is an illustration of the importance of immune function in aging, as markers of its decline correlate with age and remaining life expectancy:

Chronological age, defined as the time elapsed since birth, fails to be an accurate indicator of the rate of the aging process. This is due to the heterogeneity that aging shows in the diverse members of a population. This phenomenon led to the concept of "biological age", which estimates how well an individual functions in comparison with others of the same chronological age. Given that biological age is a better indicator than chronological age of the health, remaining healthy life span, and active life expectancy of each subject, its determination is very relevant. However, despite its simple definition, quantification of the biological age is a difficult task. Many studies have been carried out trying to obtain the most appropriate parameters for determining biological age and have been mainly focused on both physiological (respiratory function, systolic arterial tension) as well as on biochemical (albumin, cholesterol) markers. Moreover, other markers such as genetic (telomere length) or epigenetic (DNA methylation) have also been proposed. Nevertheless, despite different sets of markers being proposed in these studies, none of them have been validated. Therefore, the subject is still incomplete and more research should be carried out.

Most work on biological age has not included parameters of the immune system, which is a homeostatic system that contributes to the appropriate function of the organism. It is well known that with aging there is an increased susceptibility to infectious diseases, autoimmune processes and cancer, which indicates the presence of a less competent immune system, exerting a great influence on age-related morbidity and mortality. Since it has been demonstrated that the functioning of the immune system is an excellent marker of health and given that several age-related changes in immune functions have been linked to longevity whereas others have been shown to be predictive of mortality, the aim of the present study was to determine if some immune functions could be useful as markers of biological age and therefore as predictors of longevity.

In order to validate a potential set of parameters as markers of biological age, it is necessary to confirm that the levels shown in particular subjects reveal their real health and senescent conditions and, consequently, their rate of aging. This has to be demonstrated by meeting two requirements. The first is that if an adult individual shows values characteristic of a chronologically old individual, he or she should die prematurely. The second is that a long-lived individual, known to have experienced healthy aging, should have a value of these biomarkers similar to that of an adult. The first requisite can only be confirmed in experimental animals, given that it is a difficult task to follow-up human subjects throughout the whole aging process due to their long life span. Thus, mice were chosen for our study, which show a mean longevity of about 2 years. The second requirement can be confirmed in both human centenarians and experimental animals such as extremely long-lived mice.

Among all the possible functions of immune cells, we have focused on the ones that are the most relevant in the immune response and are known to experience an age-related decrease. In phagocytes, their ability to migrate towards the focus of infection (chemotaxis) and their capacity to ingest foreign particles (phagocytosis); in natural killer (NK) cells, their capacity to destroy tumoral cells and in lymphocytes, their ability to migrate towards the site of antigen recognition (chemotaxis) and to proliferate in response to mitogens (lymphoproliferation). Thus, in order to validate the above mentioned immune functions as markers of biological age and predictors of longevity, these functions were studied in leukocytes isolated from peripheral blood of human subjects in a cross-sectional study, from their 30s until their 100s. In addition, the same functions were analyzed in leukocytes obtained from peritoneum of mice without killing them, enabling a longitudinal study to be performed, starting at the adult age and following each animal until its death. Neutrophil chemotaxis and phagocytosis, as well as the activity of NK cells, lymphocyte chemotaxis and proliferative response showed lower values in old individuals in comparison to those in adults. Considering the state of these functions in subjects which reach a high longevity, and consequently have attained successful aging, both humans and mice showed more similar values to those observed at adult age than to those at old age.

Link: http://dx.doi.org/10.18632/aging.101116

ErythroMer as a Step Forward in Artificial Blood

A recent conference presentation on the artificial blood product ErythroMer has been doing the rounds in the press in the past few days. It sounds like the researchers involved have made meaningful progress towards overcoming many of the practical hurdles that have halted similar lines of work. You might take a look back in the Fight Aging! archives for a good open access review that covers many of the attempts to create nanoparticles and cell-like entities that can usefully augment the principal activities of red blood cells. There have been many more challenges in this line of work than might immediately spring to mind, and it makes for interesting reading. ErythroMer is a nanoparticle rather than cell based approach, which is the side of the house that I see as having the greatest potential to exceed present capabilities of our evolved blood and oxygen transport systems. So it is good to see progress on this front; it is most likely from blood substitute nanoparticles that future oxygenation enhancement technologies will arise, offering greater physical robustness and resilience to injury.

There are many lines of research that aim to produce some form of artificial blood, whether built on existing biochemistry and the mass production of cells or cell-like entities, or constructed from first principles as an oxygen-bearing nanoparticle of some form. Even narrowly effective forms of artificial blood with limited uses might nonetheless offer sizable benefits. For example, consider a form of nanoparticle that cannot be used in the long term, but can nonetheless efficiently carry oxygen: this can form the basis for a cost-effective substitute for the large amounts of blood used in trauma cases. Alternatively, a way to mass produce normal red blood cells with specific blood groups would do away with the need for the infrastructure of blood donation and thus make the whole business of banking blood much cheaper. Alternatively again, nanoparticles are much smaller than red blood cells, yet can be engineered to carry more oxygen than those blood cells. In cases of stroke, heart attack, or other ischemic injuries nanoparticles can delivery oxygen to areas that blood cells cannot reach, as well as increase the levels of oxygen reaching all tissues in the body. It isn't just a matter of therapies for the damaged, either. When thinking about enhancement of healthy physiology, something that is a little further out in the future, if today's best oxygen-carrying nanoparticles could be made safe for the long term, then when fully oxygenated an individual could undertake activity for thirty minutes or more without needing to breathe. Food for thought.

Just-Add-Water: Artificial Blood Cells Could Offer Convenient, Portable Alternative to Blood Transfusion

Researchers have developed the first artificial red blood cells designed to emulate vital functions of natural red blood cells. If confirmed safe for use in humans, the nanotechnology-based product could represent an innovative alternative to blood transfusions. The artificial cells, called ErythroMer, are designed to be freeze-dried, stored at ambient temperatures, and simply reconstituted with water when needed. Proof-of-concept studies in mice demonstrate that the artificial cells capture oxygen in the lungs and release it to tissues - the main functions of red blood cells - in a pattern that is indistinguishable from that seen in a control group of mice injected with their own blood. In rats, ErythroMer effectively resuscitated animals in shock following acute loss of 40 percent of their blood volume.

The donut-shaped artificial cells are formulated with nanotechnology and are about one-fiftieth the size of human red blood cells. A special lining encodes a control system that links ErythroMer oxygen binding to changes in blood pH, thus enhancing oxygen acquisition in the lungs and then dispensing oxygen in tissues with the greatest need. Tests show ErythroMer matches this vital oxygen binding feature of human red blood cells within 10 percent, a level the researchers say should be sufficient to stabilize a bleeding patient until a blood transfusion can be obtained. So far, tests suggest ErythroMer has overcome key barriers that halted development of previous blood substitutes, including efficacy and blood vessel narrowing. The team's next steps are testing in larger animals, ongoing safety assessment, optimizing pharmacokinetics, and ultimately conducting in-human clinical trials. The researchers are also pursuing methods for scaling up production. If further testing goes well, they estimate ErythroMer could be ready for use within 10-12 years.

ErythroMer Blood Substitute

4.5 million Americans receive blood transfusions each year, but human blood is limited by its supply and availability. under development, including Perfluorocarbon-Based Oxygen Carriers (PBOC) and Cell-Free Hemoglobin Based Carriers (HBOC), have mostly failed to preserve key physiologic functions of human blood cells. An effective artificial blood substitute will likely create and fulfill market demands for applications including hemorrhagic shock and emergency blood supplies. ErythroMer is a novel blood substitute composed of a patented nanobialys nanoparticle. Existing blood substitutes under development often trap nitric oxide unintentionally and fail to release oxygen in a context-specific manner. ErythroMer has multiple unique advantages by design: (1) Toroidal morphology resembling red blood cells; (2) Physiologic oxygen binding and release; (3) Simple system to inhibit hemoglobin auto-oxidation; (4) Limited nitric oxide sequestration; (5) Amenability to freeze-drying (lyophilization) and reconstitution. As a validation of these advantages, ErythroMer has been shown to demonstrate superior performance than other blood substitutes in a rodent model.

Erythromer (EM), a Nanoscale Bio-Synthetic Artificial Red Cell: Proof of Concept and In Vivo Efficacy Results

There is need for an artificial oxygen (O2) carrier for use when stored blood is unavailable or undesirable. To date, efforts to develop hemoglobin (Hb) based oxygen carriers (HBOCs) have failed, because of design flaws which do not preserve physiologic interactions of Hb with: O2 (they capture O2 in lungs, but do not release O2 effectively to tissue) and nitric oxide (NO) (they trap NO, causing vasoconstriction). ErythroMer design surmounts these weaknesses by: encapsulating Hb, controlling O2 capture/release with a novel 2,3-DPG shuttle and attenuating NO uptake through shell properties. The ErythroMer prototype has passed rigorous initial ex vivo and in vivo "proof of concept" testing and bench testing, which suggests this design surmounts prior challenges (by HBOCs) in emulating normal RBC physiologic interactions with O2 and NO. In models of major bleeding/anemia, ErythroMer reconstitutes normal hemodynamics and O2 delivery, observed at the system, tissue, and cellular level. ErythroMer potential for extended ambient dry storage has significant implications for portability and use. Next steps include formulation scaling, detailed study of pharmacokinetics, biodistribution and safety, as well as evaluation in large animal models of hemorrhagic shock.

Evaluating the Effects of Calorie Restriction on Biomarkers of Human Health and Aging

This very readable open access paper is illustrative of the sort of work presently taking place to try to put some numbers to the effects of calorie restriction in humans, though note that these researchers are very focused on the harms caused by excess visceral fat tissue rather than other possible mechanisms. When it comes to the practice of calorie restriction there is plenty of data for the short term benefits to health, and via existing epidemiological studies that can be extrapolated the longer term reduced risk of age-related disease, but there is very little data that sheds light on the degree to which calorie restriction should be expected to extend human life expectancy. We know it won't do as much for human life span as it does for mice, as human life expectancy is much less plastic in response to circumstances. If eating less produced a life span half as long again in our species, as it can in mice, we'd certainly know about it by now. One of the challenges for researchers in the field is to explain the reasons for this difference, given that the short term changes in mice and humans resulting from calorie restriction are in fact very similar.

Aging and wrong lifestyle choices, including inadequate dietary patterns, increase the risk of developing several diseases such as obesity and its-related chronic degenerative diseases. Interestingly, the aging program can be accelerated by obesity. It is thus likely that obesity reduces life- and health span and plays a predominant role in the onset of age-related diseases. In fact, the prevalence of obesity is globally increasing in populations and has become a burden for healthcare systems. Several studies suggest that dietary restriction (DR) regimens (e.g. intermittent fasting, calorie restriction, low calorie diet) reverse obesity and improve health in human by promoting the same molecular and metabolic adaptations that have been shown in animal models of longevity. In particular, DR in humans ameliorates several metabolic and hormonal factors that are implicated in the pathogenesis of an array of age-associated chronic metabolic diseases.

At present it is difficult to evaluate the effectiveness of DR on lifespan in humans, so that several works proposed predictive non-invasive biomarkers to evaluate the geroprotective role of DR. However, a miscellaneous of biomarkers is investigated in human intervention studies limiting the statistical robustness of the data. Whether a "biomarker-based" approach could be suitable for evaluating the effectiveness of DR still remains a matter of debate. Precision medicine is a medical model that proposes the customization of healthcare, with the identification of predictors that can help to find the effectiveness of health-promoting dietary interventions. Biomarkers represent potentially predictive tools for precision medicine but, although affordable 'omics'-based technology has enabled faster identification of putative biomarkers, their validation is still hindered by low statistical power as well as limited reproducibility of results. Herein, through meta-analysis we have evaluated the effect size of DR regimens on adipose mass and well-recognized biomarkers of healthy aging.

Herein we included all studies evaluating the impact of DR on several healthy-associated markers in human including adipose mass. Increased visceral adiposity leads to chronic inflammation, which is often associated with a number of comorbidities (e.g. hyperinsulinemia, hypertension, insulin resistance, glucose intolerance) and reduced life expectancy. Through this meta-analysis approach, we confirmed the capacity of DR to reduce total and visceral adipose mass and, interestingly, we observed a more effective visceral adipose mass reduction after DR regimens. These findings suggest that to obtain a more effective adipose mass loss, 20% in calorie reduction could be an elective strategy. Central or visceral adiposity perturbs systemic inflammation in animal models and human and relatively to this, the healthy effects of DR could be mediated by visceral adiposity reduction. Indeed, DR significantly diminished the markers of inflammation, highlighting the central role of DR-mediated adipose tissue remodelling in improving inflammatory profile in human. Furthermore, DR also increased adiponectin/leptin ratio, which is commonly associated with ameliorated insulin sensitivity in human. In line with this effect, we demonstrated that DR was successful in reducing insulin, IGF-1 and HOMA index.

Link: http://dx.doi.org/10.18632/aging.101122

Fewer Defects in RNA Splicing Linked to Multiple Ways of Slowing Aging

Researchers have found a common underlying mechanism that appears necessary for the modest slowing of aging achieved via a variety of methods, including calorie restriction and mechanisms related to the mTOR pathway. Since most aspects of cellular biochemistry influence one another, and most methods of slowing aging have (a) a very similar range of effects and (b) don't appear to stack with one another, it shouldn't be surprising that researchers continue to find shared underlying molecular machinery.

Researchers have linked the function of a core component of cells' machinery - which cuts and rejoins RNA molecules in a process known as "RNA splicing" - with longevity in the roundworm. The finding sheds light on the biological role of splicing in lifespan and suggests that manipulating specific splicing factors in humans might help promote healthy aging. "What kills neurons in Alzheimer's is certainly different from what causes cardiovascular disease, but the shared underlying risk factor for these illnesses is really age itself. So one of the big questions is: Is there a unifying theme that unfolds molecularly within various organ systems and allows these diseases to take hold?"

Due to advances in public health, life expectancy has dramatically increased worldwide over the last century. Although people are generally living longer lives, they are not necessarily living healthier lives, particularly in their last decades. Age-related diseases such as cancer, heart disease, and neurodegenerative disease are now among the leading global health burdens - a problem that will likely only worsen. In order for bodies - and cells - to maintain youthfulness, they must also maintain proper homeostasis. At the cellular level, that means keeping the flow of biological information, from genes to RNA to proteins, running smoothly and with the right balance. While a considerable amount is known about how dysfunction at the two ends of this process - genes and proteins - can accelerate aging, strikingly little is known about how the middle part, which includes RNA splicing, influences aging. Splicing enables one gene to generate multiple proteins that can act in different ways and in disparate parts of the body. "Although we know that specific splicing defects can lead to disease, we were really intrigued about de-regulation of RNA splicing as a driver of the aging process itself, because practically nothing is known about that. Put simply, splicing is a way for organisms to generate complexity from a relatively limited number of genes."

Researchers designed a series of experiments in the roundworm Caenorhabditis elegans to probe the potential connections between splicing and aging. "C. elegans is a great tool to study aging in because the worms only live for about three weeks, yet during that time they can show clear signs of age. For example, they lose muscle mass and experience declines in fertility as well as immune function." Notably, the worms' cells are transparent, so researchers harnessed fluorescent genetic tools to visualize the splicing of a single gene in real-time throughout the aging process. Not only did the scientists observe variability on a population level - after five days, some worms showed a youthful pattern of splicing while others exhibited one indicative of premature aging - but they could also use these differences in splicing (reflected fluorescently) to predict individual worms' lifespans prior to any overt signs of old age.

Interestingly, when the team looked at worms treated in ways that increase lifespan (through a technique known as dietary restriction), they found that the youthful splicing pattern was maintained throughout the worms' lives. Importantly, the phenomenon is not restricted to just one gene, but affects genes across the C. elegans genome. The finding suggests that splicing could play a broad role in the aging process, both in worms as well as humans. As they dug more deeply into the molecular links between splicing and aging, researchers zeroed in on one particular component of the splicing apparatus in worms, called splicing factor 1 (SFA-1) - a factor also present in humans. In a series of experiments, the researchers demonstrate that this factor plays a key role in pathways related to aging. SFA-1 is specifically required for lifespan extension by dietary restriction and by modulation of the TORC1 pathway components AMPK, RAGA-1 and RSKS-1/S6 kinase. Remarkably, when SFA-1 is present at abnormally high levels, it is sufficient on its own to extend lifespan.

Link: https://www.hsph.harvard.edu/news/press-releases/uncovering-smoking-gun-in-age-related-disease/

Angiotensin Receptor Autoimmunity Correlates with Age-Related Frailty and Hypertension

Autoimmunity is the name given to a very large class of conditions in which the immune system malfunctions and attacks the body's own cells and machinery. Each different inappropriate target produces a different autoimmune condition, ranging from demyelination diseases like multiple sclerosis, in which the immune system attacks processes and molecules necessary for maintenance of the sheath of myelin that coats nerves, to inflammatory diseases such as rheumatoid arthritis, in which the most obvious damage occurs at the joints. In between lie autoimmune conditions for near every important aspect of our biochemistry. While it is true that the best known autoimmune conditions are not all that age-related - rheumatoid arthritis is noted as "a disease of young women" by some sources, for example - autoimmunity in the general sense does grow with age. The immune system is immensely complex even when working correctly, but the dark forest of the aged, dsyfunctional immune system is especially poorly mapped. New forms of autoimmunity and other immune system malfunctions are discovered on a regular basis. Look at the recent unveiling of type 4 diabetes as a more esoteric example of the age-damaged immune system causing issues in important tissues. It is a condition that is probably quite prevalent in the old, yet missed until now. There are no doubt a great many forms of autoimmune disease presently hiding in the margins of age-related frailty and medical conditions, yet to be cataloged and understood.

Given that the mapping of the immune system and the catalog of autoimmunity is so far from being complete, I would argue that we should devote more attention and funding towards shortcut therapies based on immune ablation and reconstruction. Researchers have in recent years cured known forms autoimmunity with very high dose immunosuppressant or chemotherapy regimes, wiping out the overwhelming majority of immunity cells, then allowing the body to repopulate its immune system naturally. Since the configuration of the immune system, including any mistaken tendency to attack the body's own tissues, is stored in its varied cell populations, this is roughly equivalent to wiping the slate and starting over. Though the cell and tissue damage of aging isn't addressed, only the harmful alterations to immune system configuration that have accumulated over the years, there is the potential to turn back some of the clock here. Unfortunately, while successful, the processes currently used to destroy immune cells with the necessary degree of completeness are dangerous enough, both in immediate risk of death and in long-term damage to health, to only be worth it when the autoimmune condition is very harmful. That is changing, however, with the advent of side-effect-free approaches to targeted cell killing such as the c-kit and CD47 method demonstrated earlier this year, or the approach that Oisin Biotechnologies uses to destroy senescent cells.

The important point here is that clearing and recreating the immune system doesn't just deal with the autoimmunity known to the research community. It also deals with the autoimmunity that isn't known, and scientists have good reason to believe that there is quite a lot of that still hiding in the woodwork. As an example of the type, I'll point out the research linked below, in which the authors find a correlation between (a) a form of autoimmunity targeting components of the angiotensin system, which is responsible for managing blood pressure and sodium levels, and (b) the risk and degree of age-related frailty and hypertension, or raised blood pressure. The more that your own immune system is actively sabotaging the machinery, the worse off you are, in other words, and this is just one of the more subtle cases in which this is shown to be the case. It is interesting to observe that the harmful effects of this form of autoimmunity are modestly reduced by one of the classes of drug that has come into use to lower blood pressure, angiotensin receptor blockers. Thus the benefits of this type of medicine may turn out to result in part from effects that were not at all intentional. Hypertension, of course, is tremendously damaging, and it is absolutely correct to try to reduce age-related increases in blood pressure. It drives numerous forms of cardiovascular disease, from harmful remodeling and weakening of heart tissue, to increased breakage of small blood vessels in the brain, to structural failure of large blood vessels weakened by atherosclerosis. It isn't good at all.

New Link Discovered Between Class of Rogue Autoantibodies and Poor Health Outcomes

Results of a new study led offer new evidence for a strong link between angiotensin receptor autoantibodies and increased risk of frailty. The team says a large class of common blood pressure drugs that target the angiotensin receptor, called angiotensin receptor blockers (ARBs), may help patients depending on the levels of the autoantibodies. In healthy individuals, immune cells produce proteins called antibodies that attack foreign invaders to destroy them and clear them out of the system. In contrast, with autoimmune disorders, the immune cells produce autoantibodies that target the body's own tissue. "We discovered that frail older individuals have markedly higher levels of an autoantibody against its own angiotensin system. The angiotensin system is a key hormonal system that regulates blood pressure and fluid balance. The presence of these antibodies in this subset of vulnerable older adults was associated with increased inflammatory burden, and with decline in grip strength, walking speed and increased number of falls."

Individuals with higher levels of autoantibodies were also more likely to suffer from higher blood pressure. The use of ARBs in such individuals correlated with better control of their blood pressure, suggesting a possible personalized medicine approach to high blood pressure treatment in older adults.Some older adults become frail as they age, and this frailty has been associated with chronic inflammation. To examine the relationship between autoantibody levels and frailty, the research team first recruited 255 participants ages 20 to 93 in Baltimore, Maryland. Participants were separated into two categories: 169 younger adults (ages 20 to 69) and 87 older adults (70 and older). The team measured blood levels of autoantibodies and found that older adults had nearly twice the levels of autoantibodies than the younger adults - a median of 7.3 micrograms per milliliter of blood compared to the younger adult group's median level of 3.76. The researchers then used a frailty screening tool to identify frail older adults by measuring grip strength and walking speed, and asking questions about weight loss, fatigue and levels of physical activity. Older adults with high autoantibody levels were 3.9 times more likely to be frail. For every 1 microgram per milliliter of blood increase in autoantibodies, the researchers observed a decrease in hand grip strength of 5.7 pounds. Additionally, every 1 microgram per milliliter of blood increase in autoantibodies increased the odds of falling by 30 percent.

"Building off of our knowledge that these autoantibodies cause chronic inflammation, we decided to look at a class of medications, angiotensin receptor blockers, that block inflammation and are commonly prescribed to lower blood pressure." To examine the effects of autoantibodies levels on ARBs, the team collected 20-year-old data from a second patient population in Chicago and measured patients' previously collected serum for autoantibody levels. The 60 participants were 70 to 90 years old, and half had been treated with ARBs. The researchers observed similar associations between autoantibody levels and decline in grip strength and walking speed in the Chicago population. Furthermore, for every 1 microgram per milliliter increase of autoantibodies, those not receiving ARBs lived 115 days less - approximately shortened life span by 9 percent. Chronic treatment with ARBs attenuated the autoantibodies' association with decline in grip strength and increased mortality.

Discovery and Validation of Agonistic Angiotensin Receptor Autoantibodies as Biomarkers of Adverse Outcomes

Agonistic angiotensin II type I receptor autoantibodies (AT1RaAbs) have not been associated with functional measures or risk for adverse health outcomes. AT1RaAbs could be utilized to stratify patient risk and to identify patients who can benefit from angiotensin receptor blocker (ARB) treatment. Demographic and physiologic covariates were measured in a discovery set of community dwelling adults from Baltimore (N=255) and AT1RaAb associations with physical function tests and outcomes assessed. A group from Chicago (N=60) was used for validation of associations and to explore the impact of ARB treatment.

The Baltimore group had 28 subjects with falls, 32 frail subjects and 5 deaths. Higher AT1RaAbs correlated significantly with interleukin-6, systolic blood pressure, body mass index (BMI), weaker grip strength, and slower walking speed. Individuals with high AT1RaAbs were 3.9 times more likely to be at high risk after adjusting for age. Every 1 µg/ml increase in AT1RaAbs increased the odds of falling 30% after adjusting for age, gender, BMI and blood pressure. The Chicago group had 46 subjects with falls and 60 deaths. Serum AT1RaAb levels were significantly correlated with grip strength, walking speed and falls. Every 1 µg/ml increase in AT1RaAbs, decreased time to death by 9% after adjusting for age, gender, BMI and blood pressure. Chronic treatment with ARBs was associated with better control of systolic blood pressure and attenuation of decline in both grip strength and time to death.

Long Telomeres may also be Problematic

Researchers here provide initial evidence to suggest that very long telomeres may be problematic in human cells - that manipulating our biochemistry to push telomere length outside evolved norms in either direction will cause issues. Telomeres are repeated DNA sequences that cap the ends of chromosomes. There is considerable interest in telomere length in connection with aging, as average telomere length diminishes with age, though this is a statistical effect across populations and not very useful for individual predictions. There is a lot of variation over time and by health status in any given individual and between any two individuals of the same age and fitness. On the whole telomere length looks a lot like a marker of aging rather than the cause of problems: the groups that primarily seek to engineer longer telomeres in search of a way to slow aging are probably putting the cart before the horse.

Tissues are made up of somatic cells that are restricted in the number of divisions they can undertake, and supported by a small number of stem cells that are not restricted in that way. Each cell division results in a loss of telomere length, and once telomeres are too short the cell becomes senescent or self-destructs. New cells with long telomeres are created by stem cells, and those stem cells maintain long telomeres themselves via the use of telomerase. Thus average telomere length in somatic cells would seem to be a measure of some combination of stem cell activity and cell division rates - and it is known that stem cell populations decline with age. Researchers have demonstrated slowed aging in mice through increased telomerase activity, but it is far from clear as to identity of the important mechanisms in this effect: greater stem cell activity seems the most plausible, but there are a range of other options.

Ever since researchers connected the shortening of telomeres - the protective structures on the ends of chromosomes - to aging and disease, the race has been on to understand the factors that govern telomere length. Now, scientists have found that a balance of elongation and trimming in stem cells results in telomeres that are, as Goldilocks would say, not too short and not too long, but just right. "This work shows that the optimal length for telomeres is a carefully regulated range between two extremes. It was known that very short telomeres cause harm to a cell. But what was totally unexpected was our finding that damage also occurs when telomeres are very long."

Telomeres are repetitive stretches of DNA at the ends of each chromosome whose length can be increased by an enzyme called telomerase. Our cellular machinery results in a little bit of the telomere becoming lopped off each time cells replicate their DNA and divide. As telomeres shorten over time, the chromosomes themselves become vulnerable to damage. Eventually the cells die. The exception is stem cells, which use telomerase to rebuild their telomeres, allowing them to retain their ability to divide, and to develop ("differentiate") into virtually any cell type for the specific tissue or organ, be it skin, heart, liver or muscle - a quality known as pluripotency. These qualities make stem cells promising tools for regenerative therapies to combat age-related cellular damage and disease. "In our experiments, limiting telomere length compromised pluripotency, and even resulted in stem cell death. So then we wanted to know if increasing telomere length increased pluripotent capacity. Surprisingly, we found that over-elongated telomeres are more fragile and accumulate DNA damage."

The reasearchers began by investigating telomere maintenance in laboratory-cultured lines of human embryonic stem cells (ESCs). Using molecular techniques, they varied telomerase activity. Perhaps not surprisingly, cells with too little telomerase had very short telomeres and eventually the cells died. Conversely, cells with augmented levels of telomerase had very long telomeres. But instead of these cells thriving, their telomeres developed instabilities. "We were surprised to find that forcing cells to generate really long telomeres caused telomeric fragility, which can lead to initiation of cancer. These experiments question the generally accepted notion that artificially increasing telomeres could lengthen life or improve the health of an organism."

The team observed that very long telomeres activated trimming mechanisms controlled by a pair of proteins called XRCC3 and Nbs1. The lab's experiments show that reduced expression of these proteins in ESCs prevented telomere trimming, confirming that XRCC3 and Nbs1 are indeed responsible for that task. Next, the team looked at induced pluripotent stem cells (iPSCs), which are differentiated cells (e.g., skin cells) that are reprogrammed back to a stem cell-like state. iPSCs - because they can be genetically matched to donors and are easily obtainable - are common and crucial tools for potential stem cell therapies. The researchers discovered that iPSCs contain markers of telomere trimming, making their presence a useful gauge of how successfully a cell has been reprogrammed. "Stem cell reprogramming is a major scientific breakthrough, but the methods are still being perfected. Understanding how telomere length is regulated is an important step toward realizing the promise of stem cell therapies and regenerative medicine."

Link: http://www.salk.edu/news-release/goldilocks-effect-aging-research/

The Latest on Chimeric Antigen Receptor Therapy for Leukemia

The use of chimeric antigen receptors (CAR) to create engineered T cells to attack specific varieties of cancer cell, identified by their surface chemistry, is so far proving to be effective for leukemia, a cancer of the immune system. Researchers are also making inroads in adapting the therapy for use in solid tumors. While an initial group of patients treated several years ago with the first pass at CAR T cell therapy remain in remission, the news here focuses on the results from a more recent trial:

The 24 patients had undergone most standard therapies available to them and yet their chronic lymphocytic leukemia had come back strong. Almost all of them had been treated with a newly approved, targeted drug called ibrutinib; data from other studies show that most patients whose disease progresses after ibrutinib treatment do not survive long. The majority of the 24 had chromosomal markers in their leukemia cells that serve as predictors of a bad response to most standard therapies. But most of these patients, who were enrolled in a small, early-phase trial, saw their advanced tumors shrink or even disappear after an infusion of genetically engineered immune cells.

In the trial, participants' disease-fighting T cells were removed from their blood and genetically engineered to produce an artificial receptor, called a CAR, or chimeric antigen receptor, that empowered them to recognize and destroy cancer cells bearing a target molecule called CD19. After patients received chemotherapy, the CAR T cells were infused back into their bloodstream to kill their CD19-positive cancers. While all 24 patients with chronic lymphocytic leukemia, or CLL, received the experimental therapy, researchers focused in his presentation on the results in a subgroup of 19 patients who received particular chemotherapy regimens and doses of CAR T cells the researchers now prefer, based on recent data in other groups of patients on the trial. Fourteen of 19 experienced a partial or complete regression of their disease in their lymph nodes. And of the 17 who had leukemia in their bone marrow when they enrolled on the trial, the marrow became cancer-free in 15 after they received CAR T cells. "It's very pleasing to see patients with refractory disease respond like this. We had seen very good responses to the same CAR T-cell therapy in acute lymphoblastic leukemia and non-Hodgkin lymphoma, so we hoped responses would be good in CLL too."

Follow-up with CLL participants is ongoing. As per U.S. Food and Drug Administration requirements for experimental gene therapies, the research team will track patient outcomes for at least 15 years. Researchers reported that the CLL patients with the highest number of CAR T cells in their blood after infusion were most often the patients who had had the greatest extent of cancer in their marrow, blood and lymph nodes at the time of infusion. Those with more CAR T cells were also most likely to have their disease disappear from the bone marrow after the cells entered their bodies. Side effects included high fevers, due to activation of CAR T cells, and neurologic symptoms. Although one patient died from severe toxicity, the side effects experienced by other patients in the study were temporary. The researchers also reported biomarkers they had identified in patients' blood from the day after CAR T-cell infusion that were associated with the later development of the most severe toxicities. They hope these markers could eventually become the cornerstone of tests to predict and mitigate the most serious side effects of CAR T-cell infusion. "If you can find biomarkers within a day of CAR T-cell infusion, which we have, you can then look at future cohorts of patients to work out whether early intervention can help prevent toxicity."

Link: http://www.fredhutch.org/en/news/center-news/2016/12/promising-results-in-trial-of-t-cells-in-high-risk-leukemia.html

An Important Step Forward Towards a Vaccine for Periodontal Disease

The various types of gum disease and periodontal conditions create insidious forms of damage, caused by the presence of unwanted but very persistent species of bacteria found in the mouth. Most people suffer inflammation of the gums to some degree, and this is due to the activities of bacteria such as Porphyromonas gingivalis. While it is true that there are a large number of ways to remove the bacterial species found in the mouth, the challenge is that they always return, and do so very quickly, often within days. This is obviously important from the point of view of the quality of your teeth over the long term, but arguably the real reason to pay attention here is because inflammation and damage in the gums directly correlates with inflammation and damage to the heart and the rest of the cardiovascular system. Research has shown that the presence and prevalence of bacterial species associated with gum disease correlates with mortality rates, while gum disease itself correlates with cognitive decline and the presence of amyloid in the brain, to pick a few examples. If you don't keep dental health under control, your risk of suffering all of the cardiovascular diseases that are driven by chronic inflammation increases significantly, and it appears that your chances of suffering dementia get a boost as well. Unfortunately, for the whole of human history, dental health has proven to be a real challenge: gains have been incremental and still require a fair amount of ongoing work on the part of the individual.

Yet we live in an age of biotechnology and rapid, revolutionary progress. It is unthinkable that immunology, genetics, gene therapies, and advanced medical applications of the life sciences can continue to coexist with the fact that we can't get rid of a few simple bacterial species that are causing us considerable harm. Sooner or later the research community will bring all undesirable bacteria under medical control. For some years now, a number of dental research groups have been working on potential methods of permanently excluding the bacteria that cause periodontitis and other inflammatory damage to gums, teeth, and the underlying bone. This has proven to be slow going, unfortunately. Nonetheless there have been signs of progress of late. To pick an example from earlier this year, one research team has managed to rouse the innate immune system into attacking and destroying bacterial species that cause gum disease, reversing the progression of periodontitis. Similarly, the research linked below takes the form of a vaccine, training the immune system to attack one of the problem molecules produced by the Porphyromonas gingivalis bacteria that contribute to periodontitis. The dental research community tends to have a faster time to market and less of a regulatory burden than the rest of the broader medical community, so we might expect to see something along these lines reaching clinics within the next few years.

Scientists publish evidence for world-first therapeutic dental vaccine

A world-first vaccine which could eliminate or at least reduce the need for surgery and antibiotics for severe gum disease has been validated. A team of dental scientists has been working on a vaccine for chronic periodontitis for the past 15 years. Clinical trials on periodontitis patients could potentially begin in 2018. Moderate to severe periodontitis affects one in three adults and more than 50 per cent of Australians over the age of 65. It is associated with diabetes, heart disease, rheumatoid arthritis, dementia and certain cancers. It is a chronic disease that destroys gum tissue and bone supporting teeth, leading to tooth loss.

The findings represent analysis of the vaccine's effectiveness by collaborating groups. The vaccine targets enzymes produced by the bacterium Porphyromonas gingivalis, to trigger an immune response. This response produces antibodies that neutralise the pathogen's destructive toxins. P. gingivalis is known as a keystone pathogen, which means it has the potential to distort the balance of microorganisms in dental plaque, causing disease. "We currently treat periodontitis with professional cleaning sometimes involving surgery and antibiotic regimes. These methods are helpful, but in many cases the bacterium re-establishes in the dental plaque causing a microbiological imbalance so the disease continues. Periodontitis is widespread and destructive. We hold high hopes for this vaccine to improve quality of life for millions of people."

A therapeutic Porphyromonas gingivalis gingipain vaccine induces neutralising IgG1 antibodies that protect against experimental periodontitis

From epidemiological surveys moderate to severe forms of periodontitis affect one in three adults and the disease has been linked to an increased risk of cardiovascular diseases, certain cancers, preterm birth, rheumatoid arthritis and dementia related to the regular bacteremia and chronic inflammation associated with the disease. The global prevalence of severe periodontitis has been estimated from 2010 epidemiological data to be 10.5-12.0% and the global economic impact of dental diseases, of which periodontitis is a major component, has been estimated to be US$442 billion per year. The conventional therapy for periodontitis involves scaling and root planing to remove plaque microorganisms. Treatment can sometimes involve surgery to improve access and/or to reduce pocket depth and can also include the use of antibiotics and/or antimicrobials. However, treatment outcomes are variable and heavily dependent on patient compliance. Even in patients on a periodontal maintenance program involving regular professional intervention sites continue to progress and teeth are lost.

Although chronic periodontitis is associated with a polymicrobial biofilm, specific bacterial species of the biofilm such as Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia as a complex or consortium have been closely associated with clinical measures of disease. P. gingivalis is found at the base of deep periodontal pockets as microcolony blooms in the superficial layers of subgingival plaque adjacent to the periodontal pocket epithelium, which helps explain the strong association with underlying tissue inflammation and bone resorption at relatively low proportions (10-15%) of the total bacterial cell load in the pocket. Furthermore, it has been shown from studies using the mouse periodontitis model that P. gingivalis is a keystone pathogen, which dysregulates the host immune response to favour the polymicrobial biofilm disrupting homeostasis with the host to cause dysbiosis and disease.

The extracellular Arg- and Lys-specific proteinases 'gingipains' (RgpA/B and Kgp) of P. gingivalis have been implicated as major virulence factors that are critical for colonisation, penetration into host tissue, dysregulation of the immune response, dysbiosis and disease. The gingipains, in particular the Lys-specific proteinase Kgp is essential for P. gingivalis to induce alveolar bone resorption in the mouse periodontitis model. The gingipains have also been found in gingival tissue at sites of severe periodontitis at high concentrations proximal to the subgingival plaque and at lower concentrations at distal sites deeper into the gingival tissue. This has led to the development of a cogent mechanism to explain the keystone role played by P. gingivalis in the development of chronic periodontitis.

The role of P. gingivalis as a keystone pathogen in the initiation and progression of chronic periodontitis suggests that a strategy of targeting the major virulence factors of the bacterium, the gingipains, by vaccination may have utility in the prevention of P. gingivalis-induced periodontitis. Indeed, studies using the gingipains as a prophylactic vaccine that induces a high-titre antibody response in naive animals before superinfection with the pathogen have shown protection against alveolar bone resorption. However, patients with P. gingivalis-associated periodontitis harbour the pathogen at above threshold levels in subgingival plaque and exhibit an inflammatory immune response, hence it is possible that therapeutic vaccination could exacerbate inflammation and bone resorption in these patients. Here we show that therapeutic vaccination with a chimera antigen targeting the gingipains protects against alveolar bone resorption in P. gingivalis-associated experimental periodontitis and that this protection is mediated via a predominant Th2 anti-inflammatory response with the production of gingipain-neutralising IgG1 antibodies.

Common Sense on Aging and the Role of Medicine

Ronald Bailey, who has written on and off on the topic of longevity science for about as long as I've been paying attention to the subject myself, here outlines a common sense view of aging and its treatment as a medical condition. It is a sign of progress that more people are stepping up to make reasoned arguments along these lines. At the large scale and over the long term, the only research that is carried out to completion is that which is supported and understood, at least in outline, by the public at large. Lines of research that aim to control the causes of aging and thereby prevent and cure all age-related disease are not yet widely supported or appreciated, and this is why such research is still a minority concern in the scientific community. There is much work left to be done for patient advocates.

In the 21st century, almost everything that kills people, except for accidents and other unintentional causes of death, has been classified as a disease. Aging kills, so it's past time to declare it a disease too and seek cures for it. In 2015, a group of European gerontologists persuasively argued for doing just that. They rejected the common fatalistic notion that aging "constitutes a natural and universal process, while diseases are seen as deviations from the normal state." A century ago osteoporosis, rheumatoid arthritis, high blood pressure, and senility were considered part of normal aging, but now they are classified as diseases and treated. "There is no disputing the fact that aging is a 'harmful abnormality of bodily structure and function,'" they note. "What is becoming increasingly clear is that aging also has specific causes, each of which can be reduced to a cellular and molecular level, and recognizable signs and symptoms."

So why do people age and die? Basically, because of bad chemistry. People get cancer when chemical signals go haywire enabling tumors to grow. Heart attacks and strokes occur when chemical garbage accumulates in arteries and chemical glitches no longer prevent blood cells from agglomerating into dangerous clumps. The proliferation of chemical errors inside our bodies' cells eventually causes them to shut down and emit inflammatory chemicals that damage still healthy cells. Infectious diseases are essentially invasions of bad chemicals that arouse the chemicals comprising our immune systems to try and (too often) fail to destroy them.

Also in 2015, another group of European researchers pointed out that we've been identifying a lot of biomarkers for detecting the bad chemical changes in tissues and cells before they produce symptoms associated with aging. Such biomarkers enable pharmaceutical companies and physicians to discover and deploy treatments that correct cellular and molecular malfunctions and nudge our bodies' chemistry back toward optimal functioning. As a benchmark, the researchers propose the adoption of an "ideal norm" of health against which to measure anti-aging therapies. "One approach to address this challenge is to assume an 'ideal' disease-free physiological state at a certain age, for example, 25 years of age, and develop a set of interventions to keep the patients as close to that state as possible," they suggest. Most people's body chemistry is at its best when they are in their mid-twenties. In fact, Americans between ages 15 and 24 are nearly 500 times less likely to die of heart disease, 100 times less likely to die of cancer, and 230 times less likely die of influenza and pneumonia than people over the age of 65 years. For lots of us who are no longer in our twenties, television talk show host Dick Cavett summed it up well: "I don't feel old. I feel like a young man that has something wrong with him."

Link: http://reason.com/archives/2016/12/02/time-to-declare-aging-a-disease-and-get

Evidence for the Gut Microbiome to Contribute to Parkinson's Disease

In this open access paper, researchers provide evidence in support of the hypothesis that the development of Parkinson's disease starts in the gut, with changes in the microbiome that promote dysfunction:

Neurological dysfunction is the basis of numerous human diseases. Affected tissues often contain insoluble aggregates of proteins that display altered conformations, a feature believed to contribute to an estimated 50 distinct human diseases. Neurodegenerative amyloid disorders, including Alzheimer's, Huntington's, and Parkinson's diseases (PD), are each associated with a distinct amyloid protein. PD is a multifactorial disorder that has a strong environmental component, as less than 10% of cases are hereditary. Aggregation of α-synuclein (αSyn) is thought to be pathogenic in a family of diseases termed synucleinopathies, which includes PD, multiple system atrophy, and Lewy body disease. αSyn aggregation is a stepwise process, leading to oligomeric species and intransient fibrils that accumulate within neurons. Dopaminergic neurons of the substantia nigra pars compacta (SNpc) appear particularly vulnerable to effects of αSyn aggregates.

Although neurological diseases have been historically studied within the central nervous system (CNS), peripheral influences have been implicated in the onset and/or progression of diseases that impact the brain. Indeed, emerging data suggest bidirectional communication between the gut and the brain. Gastrointestinal (GI) physiology and motility are influenced by signals arising both locally within the gut and from the CNS. Neurotransmitters, immune signaling, hormones, and neuropeptides produced within the gut may, in turn, impact the brain. The human body is permanently colonized by microbes on virtually all environmentally exposed surfaces, the majority of which reside within the GI tract. Increasingly, research is beginning to uncover the profound impacts that the microbiota can have on neurodevelopment and the CNS. Dysbiosis (alterations to the microbial composition) of the human microbiome has been reported in subjects diagnosed with several neurological diseases. For example, fecal and mucosa-associated gut microbes are different between individuals with PD and healthy controls. Yet, how dysbiosis arises and whether this feature contributes to PD pathogenesis remains unknown.

Gut bacteria control the differentiation and function of immune cells in the intestine, periphery, and brain. Intriguingly, subjects with PD exhibit intestinal inflammation, and GI abnormalities such as constipation often precede motor defects by many years. It is posited that aberrant αSyn accumulation initiates in the gut and propagates via the vagus nerve to the brain in a prion-like fashion. This notion is supported by pathophysiologic evidence: αSyn inclusions appear early in the enteric nervous system (ENS) and the glossopharyngeal and vagal nerves. Further, injection of αSyn fibrils into the gut tissue of healthy rodents is sufficient to induce pathology within the vagus nerve and brainstem. However, the notion that αSyn aggregation initiates in the ENS and spreads to the CNS via retrograde transmission remains controversial, and experimental support for a gut microbial connection to PD is lacking.

Based on the common occurrence of GI symptoms in PD, dysbiosis among PD patients, and evidence that the microbiota impacts CNS function, we tested the hypothesis that gut bacteria regulate the hallmark motor deficits and pathophysiology of synucleinopathies. Herein, we report that the microbiota is necessary to promote αSyn pathology, neuroinflammation, and characteristic motor features in a validated mouse model. We identify specific microbial metabolites, short-chain fatty acids, that are sufficient to promote disease symptoms. Remarkably, fecal microbes from PD patients impair motor function significantly more than microbiota from healthy controls when transplanted into mice. Together, these results suggest that gut microbes may play a critical and functional role in the pathogenesis of synucleinopathies such as PD.

Link: http://dx.doi.org/10.1016/j.cell.2016.11.018

The Slow Death of the Self that is Produced by the Normal Operation of Human Memory

People are terrified of dementia, by the loss of the self that results from the final stages of the accumulation of age-related damage in the brain. Whether this is loss of data or merely loss of access to data, that data being encoded in the structures of neurons and their connecting synapses, depends upon the details along the way. Either option amounts to the same thing for someone in the midst of the condition when there is only faint prospect of therapies arriving soon enough to matter. But if dementia is an asymptotic approach to 100% loss of data, what to make of the fact that we are, on a day to day basis, largely accepting of our normal relationship with the data of the mind, in which we lose 98% of everything that we experience within a few weeks of the event? A week from now you will not remember reading this, nor will there be any trace of what took place in the surrounding minutes before and after. You will have to guess at how you spent your time, what you were thinking, who you were at that moment. We are, every one of us, thin and translucent ghosts of our own history, mere summaries of a rich set of data that is now gone.

Yet we get by. Normal is normal, but that doesn't mean it is good, or that it should go unexamined. To put this another way, there was a person who lived a few decades ago in the UK, and got by. Later, there was another person who came to the US and spent time here, as people do. I know about as much about those individuals as I do about friends of long standing, perhaps just a little more. Yet both of them were me. All of that remains of them, of their richness of data, are the echoes I carry with me now. I have the memories burned in by adrenaline or, to a lesser extent, by sheer boring repetition, but those are just signposts in the mist by this point. Ask me who I was back then, and the answer will be largely extrapolation. Are those individuals dead? Am I so different that such a question makes sense to ask? To what extent is the self burning away and vanishing because we have a poor capacity for remembrance? To what extent is change death, in other words? Here of course I do little more than wave my hands at questions that have been debated at great length in the philosophy community.

Those of us who are generally opposed to the idea of being scanned, uploaded, and copied have the view that a copy of the self is not the self. It is its own separate individual. Individuality stems from the combination of pattern of information and the matter that the pattern is bound to. It isn't clear that, for example, an emulation running in an abstraction layer over computing hardware can be considered a continuous entity, rather than a unending series of nanosecond individuals assembled and then destroyed. In the continuity view of identity, a Ship of Theseus sort of a viewpoint, you are still you even if all your component parts are slowly replaced over time. There is a sizable grey area at the border between small parts and slow replacement, which is fine, and large parts and rapid replacement, which is the same as death. If someone removes half of your brain in one go and replaces it with a hypothetical machine that accepts exactly the same inputs and produces exactly the same outputs where it connects to the remaining brain tissue, I would say that this means that you just died, even though an entity that thinks in the same way as you did continues onward. Conversely, replacing neurons one by one with machines that perform the same functions, and allowing time for each neuron to reach equilibrium with its neighbors, seems acceptable.

Continuity comes attached at the hip to change of the self over time. Life is change, and we celebrate it. But we lose so very much in the course of that change that it seems matters really could be better managed. The figure for 98% loss of memory over weeks arises from self-experiments carried out by a determined fellow in the late 1800s, and which have been repeated every so often by the research community ever since. A replication paper was published just last year, for example. This enormous loss is the way things work for normal humans, and coupled with the adrenaline mechanism for selective additional memory of events that matter, one can see how this sort of a system might have evolved. A prehistoric lifespan is the same few tasks with very minor variations repeated over and again until death or disability, interspersed with a much smaller number of painful and terrifying learning experiences, with each new generation running the same rat wheel as the previous.

There are claims of people with extraordinary memory, or even eidetic or photographic memory, but the scientific community is far from settled on the question of the degree to which these claims result from (a) misinterpreting the top end of the curve for normal variation in memory capacity, versus (b) narrowly specialized memory training, versus (c) some form of genuinely unusual and exceptional ability based on neurobiological differences yet to be described. The mechanisms of memory are being deciphered in the laboratory, however, and there are various demonstrations of a modest degree of enhanced memory in animal studies. The question of whether greatly enhanced memory can be induced through near future medicine remains open: it will certainly happen eventually, but when will it start in earnest, and when will it go beyond adding only few more percentage points to the fraction of events we recall from our lives? It seems to me that this is a goal that should be given a far greater priority than is the case today. Consider that if we had perfect memory, what would we think of someone who forget near everything he or she did? We would call it a medical condition and offer support, in the same way that the medical community seeks to treat and aid people suffering age-related cognitive decline or amnesia today. If there were a great many of those people, there would be an enormous investment in the search for a cure, just as we do today for Alzheimer's disease. But because our disability is normal and shared, there is no such effort.

Embryonic Gene Hoxa9 Reactivates with Age to Limit Muscle Stem Cells

The changes that take place in stem cell populations with age are most studied in muscle tissue at the present time. Stem cells in old tissue spend ever more time quiescent rather than active, and thus the supply of new somatic cells needed to maintain and repair muscle declines. From the evidence accumulated to date this appears to be largely driven by changes in signaling rather than molecular damage to the stem cells themselves, though there is that as well. Researchers are attempting to catalog these signals with the hope of overriding them in order to restore youthful levels of regeneration in aged patients, and the research noted here is one example of this type of research. The decline in stem cell activity with age is thought to be part of an evolved balance between death by lack of tissue maintenance on the one hand and death by cancer on the other. Lower rates of stem cell activity reduces the chance of a damaged cell running amok. However, the use of stem cell therapies that change signals to put native cells back to work, and studies of telomerase gene therapy that has much the same effect, so far suggest that there is a fair amount of room to improve the situation without significantly raising the risk of cancer.

The development of the embryo during pregnancy is one of the most complex processes in life. Genes are strongly activated, and developmental pathways must do their job in a highly accurate and precisely timed manner. So-called Hox-genes play an important regulatory role in this process. Although remaining detectable in stem cells of adult tissues throughout life, after birth they are only rarely active. Now, however, researchers have shown that, in old age, one of these Hox-genes (Hoxa9) is strongly re-activated in murine muscle stem cells after injury; leading to a decline in the regenerative capacity of skeletal muscle. Interestingly, when this faulty gene re-activation was inhibited by chemical compounds, muscle regeneration was improved in aging mice, thus suggesting novel therapeutic approaches aimed at improving muscle regeneration in old age.

The biggest surprise from the current study is that the re-activation of Hoxa9 after muscle injury in old age impairs the functionality of muscle stem cells instead of improving it. Originally, Hoxa9-induced developmental pathways are responsible for the proper development of body axes - for example, during development of the fingers of a hand. A decline in stem cell functionality leads to an unavoidable decrease in the regenerative capacity of the whole skeletal muscle. With age, this may weaken the muscular strength after injury. The courses of stem cell and tissue aging are yet to be completely understood. It has already been recognized that signals which control the development of the embryo become activated in aging stem cells. However, the regulator-genes controlling these signals have not yet been analyzed in aging. "From an evolutionary perspective, Hox-genes are very old. They regulate organ development across almost the entire animal kingdom - from flies up to humans. It is a huge surprise that the faulty re-activation of these genes leads to stem cell aging in muscle. This finding will fundamentally influence our understanding of the courses of aging. Surprisingly, old muscle stem cells did not show a faulty activation of the epigenome in quiescence - the resting stage in non-injured muscle. Only in response to a muscle injury, do the stem cells display an abnormal epigenetic stress response, which leads to the opening of DNA and, thus, to the activation of developmental pathways."

The researchers now plan to investigate whether a similar re-activation of embryonic genes is also causative for the loss of muscle maintenance in aging humans. Medical compounds that limit alterations in the epigenome may improve the regenerative capacity of muscles in old mice. Thus far, this approach is too unspecific and affects the modification of genes in several cells and tissues. For this reason, a collaborative study is primed to investigate whether a nanoparticle-induced, target-specific inhibition of Hox-genes in muscle stem cells is feasible and, if so, would it be sufficient to improve muscle regeneration and maintenance.

Link: http://www.leibniz-fli.de/nc/institute/public-relations/press-releases/research/detailpage/?tx_news_pi1%5Bnews%5D=3310

A Reasonable Perspective on Cryonics

In this article, one of the scientists involved in our rejuvenation research community outlines a very reasonable view on cryonics and cryopreservation. Cryonics is the low-temperature preservation of at least the brain following death, done these days with the use of cryoprotectants and vitrifiction to minimize ice crystal formation. It offers an unknown chance at a future restoration to life: technology marches onwards year after year, and for so long as the structures that encode the data of the mind are preserved, there is the possibility of living again in a future age that has mastered the technologies needed for restoration. This would include, at a minimum, comprehensive control over cellular biology and some form of advanced molecular nanotechnology. Even in our present era, there is considerable interest in developing reversible vitrification for organ storage, to ease the logistics of tissue engineering and organ donation and transplantation, and early proof of concept experiments have taken place in that field. The types of technology that would be needed to restore a preserved cryonics patient can be envisaged by extrapolation from present efforts in that field and in the work being carried out on rejuvenation therapies.

A teenager who tragically died of cancer recently has become the latest among a tiny but growing number of people to be cryogenically frozen after death. These individuals were hoping that advances in science will one day allow them to be woken up and cured of the conditions that killed them. But how likely is it that such a day will ever come? Nature has shown us that it is possible to cryopreserve animals like reptiles, amphibians, worms and insects. Nematode worms trained to recognise certain smells retain this memory after being frozen. The wood frog (Rana sylvatica) freezes during winter into a block of ice and hops around the following spring. However, in human tissue each freeze-thaw process causes significant damage. Understanding and minimising this damage is one of the aims of cryobiology.

At the cellular level, these damages are still poorly understood, but can be controlled. Each innovation in the field relies on two aspects: improving preservation during freezing and advancing recovery after thawing. During freezing, damage can be avoided by carefully modulating temperatures and by relying on various types of cryoprotectants. One of the main objectives is to inhibit ice formation which can destroy cells and tissues by displacing and rupturing them. For that reason, a smooth transition to a "glassy stage" (vitrification) by rapid cooling, rather than "freezing", is the aim. Reviving whole bodies also poses its own challenges as organs need to commence function homogeneously. The challenges of restoring the flow of blood to organs and tissues are already well-known in emergency medicine. But it is perhaps encouraging that cooling itself does not only have negative effects - it can actually mitigate trauma. In fact, drowning victims who have been revived seem to have been protected by the cold water - something that has led to longstanding research into using low-temperature approaches during surgery.

The pacemakers of scientific innovation in cryobiology are both medical and economic. Many advances in cell preservation are driven by the infertility sector and an emerging regenerative medicine sector. Cryopreserved and vitrified cells and simple tissues (eggs, sperm, bone marrow, stem cells, cornea, skin) are already regularly thawed and transplanted. Work has also started on cryopreservation of "simple" body parts such as fingers and legs. Some complex organs (kidney, liver, intestines) have been cryopreserved, thawed, and successfully re-transplanted into an animal. While transplantation of human organs currently relies on chilled, not frozen, organs, there is a strengthening case for developing cryopreservation of whole organs for therapeutic purposes.

But there's another huge hurdle for cryonics: to not only repair the damage incurred due to the freezing process but also to reverse the damage that led to death - and in such a manner that the individual resumes conscious existence. So will it one day be possible to cryopreserve a human brain in such a manner that it can be revived intact? Success will depend on the quality of the cryopreservation as well as the quality of the revival technology. Where the former is flawed, as it would be with current technologies, the demands on the latter increase. This has led to the suggestion that effective repair must inevitably rely on highly advanced nanotechnology - a field once considered science fiction. The idea is that tiny, artificial molecular machines could one day repair all sorts of damage to our cells and tissues caused by cryonics extremely quickly, making revival possible. Given the rapid advances in this field, it may seem hasty to dismiss the entire scientific aim behind cryonics.

Link: http://theconversation.com/will-we-ever-be-able-to-bring-cryogenically-frozen-corpses-back-to-life-a-cryobiologist-explains-69500

Support for Impaired Drainage Theories of Alzheimer's Disease

Alzheimer's disease is associated with the growing presence of solid deposits of misfolded amyloid-β and altered tau protein in the brain. A halo of complex and much debated biochemistry connects these forms of metabolic waste with the dysfunction and death of neurons; it isn't the amyloid or the tau itself, but related molecules and their interactions that cause pathology, arising as a result of the existence of the amyloid and tau. Clearing these unwanted proteins should help to turn back the progression of Alzheimer's, a goal complicated by the fact that many Alzheimer's patients also suffer from other forms of neurodegeneration, such as the vascular dementia that results from hypertension, blood vessel stiffness and structural failure, and many tiny zones of cell death caused by blood vessel failures over the years. Unfortunately in addition to these complications, safely clearing amyloid in the human brain has proven to be very challenging. Most efforts to date have used forms of immunotherapy, and only recently have good results emerged in human trials. The field of the past decade is littered with the remains of failed efforts. Clearance of tau has much further to go in order to arrive at the point of human trials, not having received the same level of attention and funding over the past decade. It is becoming apparent that it will also have to be removed from the brain, however.

Why do amyloid and tau aggregate in the aging brain? There are many competing theories. The brain, its immune system, and its surrounding support structures are enormously complex and only partially understood. In many ways the quest to understand Alzheimer's disease is one and the same with the quest to understand the brain as a whole. A cure for Alzheimer's is the goal that brings in funding for fundamental research into the mechanisms of thought, memory, and aging, as well as details of cellular behavior, inflammation and immunology in the brain, distinctly different and more complicated than elsewhere in the body. One interesting point regarding amyloid-β is that its levels in brain tissue and cerebrospinal fluid are very dynamic. It is constantly created and destroyed, and so the accumulation with age is not a matter of slow and steady creation, but rather results from the interaction and changing nature of numerous processes.

One class of theories seeking to explain increased amounts of amyloid-β with aging postulate a gradual failure in mechanisms of clearance, such as immune activity, since the immune system is responsible for removing many forms of unwanted metabolic waste, or filtration of cerebrospinal fluid by the choroid plexus. Alzheimer's becomes a tertiary consequence at the end of a chain of failures that starts with some form of age-related decline in the effectiveness of clearance of metabolic waste in the brain. Cerebrospinal fluid isn't just filtered, however. Small amounts continually drain away from the brain via a variety of small channels in the head, to be replaced by new fluid generated by the choroid plexus. In recent years some researchers have suggested that this drainage is an important mode of clearance for amyloid and tau, and that the necessary channels becomes impaired due to other forms of age-related damage and change. You might look at the efforts of Leucadia Therapeutics, for example, a startup company funded by the Methuselah Foundation, as they work to prove or disprove this mechanism as a cause of Alzheimer's disease. With that in mind, I noticed the following research today, in which the authors offer further evidence in support of the class of hypotheses that involve impaired cerebrospinal fluid drainage.

Study suggests possible new target for treating and preventing Alzheimer's

The new study examined aquaporin-4, a type of membrane protein in the brain. Using brains donated for scientific research, researchers discovered a correlation between the prevalence of aquaporin-4 among older people who did not suffer from Alzheimer's as compared to those who had the disease. Aquaporin-4 is a key part of a brain-wide network of channels, collectively known as the glymphatic system, that permits cerebral-spinal fluid from outside the brain to wash away proteins such as amyloid and tau that build up within the brain. These proteins tend to accumulate in the brains of some people suffering from Alzheimer's, which may play a role in destroying nerve cells in the brain over time.

The study closely examined 79 brains donated through the Oregon Brain Bank. They were separated into three groups: People younger than 60 without a history of neurological disease; people older than 60 with a history of Alzheimer's; and people older than 60 without Alzheimer's. Researchers found that in the brains of younger people and older people without Alzheimer's, the aquaporin-4 protein was well organized, lining the blood vessels of the brain. However within the brains of people with Alzheimer's, the aquaporin-4 protein appeared disorganized, which may reflect an inability of these brains to efficiently clear away wastes like amyloid beta. The study concluded that future research focusing on aquaporin-4 - either through its form or function - may ultimately lead to medication to treat or prevent Alzheimer's disease.

Association of Perivascular Localization of Aquaporin-4 With Cognition and Alzheimer Disease in Aging Brains

Since 2013, we have defined a brain wide perivascular pathway, termed the glymphatic system, that facilitates the recirculation of cerebrospinal fluid (CSF) through the brain parenchyma and supports the clearance of interstitial solutes including amyloid-β (Aβ) and tau. Perivascular exchange of CSF and interstitial fluid is dependent on the astroglial water channel aquaporin-4 (AQP4), which is localized to perivascular astrocytic endfeet that ensheathe the cerebral vasculature. We demonstrated that perivascular CSF recirculation and Aβ clearance are impaired in the aging mouse brain, impairment that was associated with the loss of perivascular AQP4 localization. Prior studies in postmortem human tissue show that AQP4 is up regulated and that localization of AQP4 to the cerebral vasculature is disrupted in the AD cortex. This suggests that age-related mislocalization of AQP4 may slow glymphatic function and promote protein aggregation and neurodegeneration.

In this study, we assessed AQP4 expression and perivascular localization in human brain samples including individuals of different ages and with different cognitive and neuropathological AD profiles. Expression of AQP4 was associated with advancing age among all individuals. Perivascular AQP4 localization was significantly associated with AD status independent of age and was preserved among eldest individuals older than 85 years of age who remained cognitively intact. When controlling for age, loss of perivascular AQP4 localization was associated with increased amyloid-β burden.

Another Group Argues for Alzheimer's Disease to be a Diabetic Condition

A number of the aspects of Alzheimer's disease biochemistry have a strong similarity to aspects of type 2 diabetes biochemistry. Alzheimer's also has the same risk factors, such as the presence of excess visceral fat tissue. Some researchers have gone so far as to call for the classification of Alzheimer's as type 3 diabetes. While not official, there has been enough of this sort of discussion over the years that when type 4 diabetes was discovered it had to be called type 4 in order to avoid the inevitable confusion. It is very unclear as to where the diabetic aspects of Alzheimer's disease fit in the long chain of cause and effect that leads from fundamental damage that causes aging to age-related disease, and so equally unclear as to how effective it can be in the best case to undertake efforts to adjust this biochemistry. Nonetheless, the research linked here is one of many examples in which Alzheimer's has facets that strongly resemble diabetes:

Researchers have found a promising treatment for Alzheimer's disease, by noticing a similarity in the way insulin signaling works in the brain and in the pancreas of diabetic patients. In the pancreas, the Kir6.2 channel blockade increases the insulin signaling, and insulin signaling decreases the blood glucose levels. In the brain, insulin signaling increases the acquisition of memory through CaM kinase II activation by Kir6.2 channel blockade. The research group thus concluded that Alzheimer's disease can be described as a diabetic disorder of the brain. Memantine, a drug widely used to treat Alzheimer's disease, is a well known inhibitor of the N-methyl-D-aspartate (NMDA) receptors that prevent excessive glutamate transmission in the brain. Researchers have now found that memantine also inhibits the ATP-sensitive potassium channel (Kir6.2 channel), improving insulin signal dysfunction in the brain.

In their experiment with mice, the researchers found that memantine treatment improved impaired hippocampal long-term potentiation (LTP) and memory-related behaviors in the mice through the inhibition of KATP channel Kir6.2. "Our results suggest that Kir6.2 blockade in dendritic spines by memantine regulates CaMKII activity by increasing intracellular Ca2+ mobilization, which in turn improves cognitive function by promoting AMPAR trafficking into the postsynaptic membrane. Since KATP channels Kir6.1 or Kir6.2 are critical components of sulfonylurea receptors (SURs) which is downstream insulin receptor signaling, the KATP channel inhibition by Memantine mediates the anti-diabetic drug action in peripheral tissues. And this leads to improved cognitive functions and improved memory retention among Alzheimer's patients." The researchers now hope that results of their study and the parallels drawn with diabetes, will lead to new treatments for Alzheimer's disease, using the inhibition of Kir6.2 channel.

Link: http://www.tohoku.ac.jp/en/press/alzheimers_diabetic_brain_disorder.html

Stem Cell Research and the Treatment of Neurodegenerative Diseases

In this open access review paper, the authors make a case for more human trials in the development of stem cell therapies to treat neurodegenerative diseases. An abundance of caution and heavy regulatory burden drives greater use of animal studies than is perhaps merited given the safety data derived from the first of those studies, which in turn leads to high cost and a high rate of failure in development. A more rapid move to human trials after proving safety in animals is one possible solution to this problem. Another is for large improvements in the quality and cost of on-demand growth of small brain tissue sections that exhibit specific disease characteristics, but even then it is still important to transition to human trials sooner after safety is proven rather than later.

Progress in the field of clinical research and medicine has decreased global mortality drastically. The developed countries have extended the life span of their aging population. However, the modern world is now faced with the issues of aging and age related disorders. Neurodegeneration and neurodegenerative disorders are one of the major health implications faced by the aging population. Neurodegenerative disorders have been thoroughly investigated using animal models, primary cultures, and post mortem human brain tissues. Though informative, these approaches have some limitations. Data obtained from animal models fails to directly correlate with that of humans because a rodent brain is not an exact mimic of a human brain. Despite being highly conserved evolutionarily, mammalian genomes are not identical. Therefore species difference prevents the animal data from successful validation during clinical field trials which poses a severe economic burden. Preclinical studies often do not efficiently translate to the clinic and the clinical trial failures have been reported time and again. Primary culture of neurons is challenging because these are the post mitotic differentiated cells which are difficult to sustain in the in-vitro conditions. Ethical constraints have held back human based research and thus the best possible source of human samples are the postmortem brain tissues. However, these autopsied samples depict the end stages of the disease and do not give much insight into the intricacies of the disease' developing stages. Researchers are not willing to subject the human beings to untested interventions, but the choices have been limited so far.

Majority of neurodegenerative disorders have been incurable (Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis) so far but timely diagnosis can help in the management and symptom alleviation. However, researchers across the world are continuously striving to achieve the cure and hope to achieve fruitful results in the near future. Neurodegeneration studies are largely divided into two major categories. One is the experimental modeling strategy which allows for a comprehensive understanding of the disease such as the etiology, pathophysiology, genotypic-phenotypic interactions, symptomatic, and mechanistic insights. The second is the medical approach which deals with the treatment, therapy, and disease management. Stem cells and iPSCs find widespread application for both, disease modeling as well as transplantation and regenerative therapeutics. In the present review we shall discuss the applicability of stem cell research in the field of neurodegenerative disease modeling and provide the current updates of how stem cell and induced pluripotent stem cell based studies have been employed to address the diagnosis and therapy of the most common neurodegenerative disorders. We shall briefly touch upon the advances and preferable methodologies employing stem cell and iPSC culture such as the three dimensional (3D) culture which has revolutionized the current trend of in-vitro studies. The article intends to highlight the fact, that though animal based in-vivo research is absolutely necessary for the neuroscience research, one cannot wholly and solely depend upon it and human based stem cell driven research has and will open newer avenues for the neurodegenerative disorders′ modeling and treatment.

Link: http://dx.doi.org/10.3389/fmolb.2016.00072