A Review of Telomerase as a Therapeutic Target

Telomerase provides the primary mechanism by which cells lengthen their telomeres. In our species only stem cells and cancer cells do this, while in mice more types of cell use more telomerase. Telomere length determines the limit to cell divisions, a little of the length being lost each time a cell divides. Cells that can lengthen their telomeres can continue dividing indefinitely, and that is how stem cells can continually deliver a useful supply of daughter cells to support surrounding tissues. It is also how cancer grows. Cancer and regeneration are the two sides of the same coin of growth and regeneration, one controlled, the other uncontrolled. Thus, broadly speaking, there are two things that can be done with telomerase in medicine, and both projects, while in the comparatively early stages, have a fair number of research groups involved.

Firstly, blocking the ability of telomerase to lengthen telomeres is the larger part of the basis for a universal cancer therapy. Some 90% of cancers abuse telomerase in order to grow and spread. If that can be shut down, then the cancer will be halted in its tracks - any cancer. The challenge of cancer research is not that it is hard and expensive, but rather that most approaches to treating cancer are highly specific to just a few types out of the hundreds of forms of cancerous tissue. This is a poor strategy. Meaningful progress towards defeating cancer will require the development of therapies that can instead be applied to many, or for preference all cancers. Thus blocking telomere lengthening has the potential to completely change the economics of the field, making it feasible to bring an end to cancer within our lifetimes and within the present budget allocated to that goal.

Secondly, taking the opposite approach to increase the activity of telomerase may prove to be a way to enhance regeneration and tissue maintenance, and therefore compensate for the onset of aging and age-related degeneration. In animal studies the outcome of additional telomerase is somewhat analogous to the effects of stem cell therapies, in that cellular activity increases to produce greater healing than normally take place. This is of particular interest in the old, who suffer in part because stem cell activity declines with age, and frailty and organ failure encroaches as a result. Telomerase gene therapies have been used to extend life in mice, and have the secondary effect in that species of reducing cancer rates. This second item is a very interesting outcome, given the role of telomerase in cancer, and we might speculate that it occurs because of improved immune function - enough of a benefit there to counteract any increased cancer risk as old and damaged cells are given the opportunity to do more and divide more often. There is uncertainty as to whether the outcomes in mice reflect the balance of effects that would occur in humans, since mice have a very different balance of telomerase activity. Investigations are ongoing, and great deal remains to be explained.

Therapeutic Targeting of Telomerase

Telomere length and cell function can be preserved by the human reverse transcriptase telomerase (hTERT), which synthesizes the new telomeric DNA from a RNA template, but is normally restricted to cells needing a high proliferative capacity, such as stem cells. Consequently, telomerase-based therapies to elongate short telomeres are developed, some of which have successfully reached the stage I in clinical trials. Telomerase is also permissive for tumorigenesis and 90% of all malignant tumors use telomerase to obtain immortality. Thus, reversal of telomerase upregulation in tumor cells is a potential strategy to treat cancer.

Natural and small-molecule telomerase inhibitors, immunotherapeutic approaches, oligonucleotide inhibitors, and telomerase-directed gene therapy are useful treatment strategies. Telomerase is more widely expressed than any other tumor marker. The low expression in normal tissues, together with the longer telomeres in normal stem cells versus cancer cells, provides some degree of specificity with low risk of toxicity. However, long term telomerase inhibition may elicit negative effects in highly-proliferative cells which need telomerase for survival, and it may interfere with telomere-independent physiological functions. Moreover, only a few hTERT molecules are required to overcome senescence in cancer cells, and telomerase inhibition requires proliferating cells over a sufficient number of population doublings to induce tumor suppressive senescence. These limitations may explain the moderate success rates in many clinical studies.

Despite extensive studies, only one vaccine and one telomerase antagonist are routinely used in clinical work. For complete eradication of all subpopulations of cancer cells a simultaneous targeting of several mechanisms will likely be needed. Possible technical improvements have been proposed including the development of more specific inhibitors, methods to increase the efficacy of vaccination methods, and personalized approaches.

Telomerase activation and cell rejuvenation is successfully used in regenerative medicine for tissue engineering and reconstructive surgery. However, there are also a number of pitfalls in the treatment with telomerase activating procedures for the whole organism and for longer periods of time. Extended cell lifespan may accumulate rare genetic and epigenetic aberrations that can contribute to malignant transformation. Therefore, novel vector systems have been developed for a 'mild' integration of telomerase into the host genome and loss of the vector in rapidly-proliferating cells. It is currently unclear if this technique can also be used in human beings to treat chronic diseases, such as atherosclerosis.

It is important to note that therapies like telomerase enhancement or stem cell transplants do little to nothing to address a range of other issues that cause age-related disease. Age-related changes such as mitochondrial DNA damage, persistent cross-links, and the accumulation of other metabolic waste such as lipofuscin are not going to be meaningfully affected. Each of those individually probably causes enough harm to kill people. So while adjusting stem cells and regeneration can be beneficial, it does not repair these forms of underlying damage, and thus is limited in the degree to which it can turn back the clock. A good way to look at this is in terms of the stem cell therapies now becoming more widely available that address joint paint and dysfunction. They help many patients to a greater degree than any other form of therapy presently available. They do not and cannot remove liver spots or undo macular degeneration, or turn back stiffening of arteries and loss of elasticity of skin, all items driven by the forms of damage noted above. Rejuvenation will in the end require a complete toolkit.

Building a Tau Immunotherapy that does not Increase Inflammation

Alzheimer's disease is associated with the aggregation of misfolded amyloid-β and tau proteins. The consensus position is that these aggregates are the primary cause of pathology, though the biochemistry involved is exceedingly complex and still being mapped. A sizable faction in the research community is working on immunotherapies to clear out misfolded amyoid, tau, or both, though so far this has proven to be more challenging than hoped. One of the potential issues is the risk of such a therapy generating greater inflammation in a patient whose condition is already inflammatory. This article gives an overview of one line of research into tau immunotherapies, and notes a recent step forward towards solving the inflammation problem:

The tangled buildup of tau protein in brain cells is a hallmark of the cognitive decline linked with Alzheimer's disease. Antibodies have been shown to block tau's spread, but some scientists worry it could also fuel inflammation. Now, researchers have found that an antibody's ability to recruit immune cells - known as its effector function - is not necessary for stopping tau's spread. Alzheimer's disease causes a characteristic constellation of pathologies: accumulation of amyloid-β plaques outside neurons, neurofibrillary tangles of tau inside brain cells, and chronic inflammation. Clinical research has mostly focused on targeting amyloid-β with antibody therapies, and several treatments based on this approach are currently in clinical trials. But recent efforts have zeroed in on tau as a new potential target.

Antibodies are known to spur the brain's defense system, microglia, to absorb and degrade tau, but their recruitment of immune cells may also worsen inflammation. Researchers wondered whether effector function was necessary for stopping tau's spread. To find out, the researchers raised transgenic mice that develop a tau pathology similar to that seen in Alzheimer's disease. The team treated the animals with antibodies that had either strong effector function or none at all. The animals that received antibodies with no effector function were able to clear tau as effectively as those that received full-effector function antibodies. "Low and behold, we don't need effector function in order to achieve a halting of accumulation of tau pathology." The findings suggest the antibodies could have an indirect effect on microglial activation, and may be unnecessary for therapeutic effect. The findings are likely to reignite an ongoing debate in the field over whether antibodies target tau inside or outside brain cells.

Link: http://www.the-scientist.com/?articles.view/articleNo/46677/title/Toward-an-Immunotherapy-for-Alzheimer-s-Disease/

How Extracellular Matrix Scaffolds Influence Cell Behavior in Therapies

One approach to regenerative medicine is to use donor extracellular matrix as a scaffolding material. The extracellular matrix is the support structure created by cells that determines the structural properties of a tissue. Its presence in a regenerative therapy can guide cells to rebuild lost tissue to some degree, but a better understanding of how this actually works under the hood could be used to improve the quality of the outcome, as well as to hopefully allow the development of a viable artificial replacement for natural donor matrix materials.

Researchers have identified a mechanism by which bioscaffolds used in regenerative medicine influence cellular behavior, a question that has remained unanswered since the technology was first developed several decades ago. Bioscaffolds composed of extracellular matrix (ECM) derived from pig tissue promote tissue repair and reconstruction. Currently, these bioscaffolds are used to treat a wide variety of illnesses such hernias and esophageal cancer, as well as to regrow muscle tissue lost in battlefield wounds and other serious injuries.

Researchers know that ECM is able to instruct the human body to replace injured or missing tissue, but exactly how the ECM material influences cells to cause functional tissue regrowth has remained a fundamental unanswered question in the field of regenerative medicine. In the new study, the team showed that cellular communication occurs using nanovesicles, extremely tiny fluid-filled sacs that bud off from a cell's outer surface and allow cells to communicate by transferring proteins, DNA and other "cargo" from one cell to another. Exosomes are present in biological fluids such as blood, saliva and urine, where they influence a variety of cellular behaviors, but researchers had yet to identify them in solid body tissues. "We always thought exosomes are free floating, but recently wondered if they are also present in the solid ECM and might facilitate the cellular communication that is critical to regenerative processes."

To explore this possibility, researchers used specialized proteins to break up the ECM, similar to the process that occurs when a bioscaffold becomes incorporated into the recipient's tissue. The research team then exposed two different cell types - immune cells and neuronal stem cells - to isolated matrix bound vesicles, finding that they caused both cell types to mimic their normal regrowth behaviors. "Sure enough, we found that vesicles are embedded within the ECM. In fact, these bioscaffolds are loaded with these vesicles. This study showed us that the matrix bound vesicles are clearly active, can influence cellular behavior and are possibly the primary mechanism by which bioscaffolds cause tissue regrowth in the body."

Link: http://www.eurekalert.org/pub_releases/2016-07/uops-prs072816.php

The Effects of Retirement are Complex

Whenever looking at correlations between behavior and lifespan, or behavior and health, one should always ask whether calorie intake or physical activity level could be involved. Both animal and human studies tell us that the effects of both of these items are large in comparison to almost all other commonly varying factors, with smoking being one of the few exceptions to that rule. In recent years, the growing use of accelerometers rather than self-reporting in studies of exercise have revealed that even quite modest physical activity correlates with a sizable difference in outcomes in later life. Animal studies tell us that exercise does in fact cause improvements in health and at least healthy life span if not maximum life span. It is very hard to pull out causation from human statistics, but it is reasonable to arrange one's life on the basis that causation in other mammals matches up with causation in humans in this matter.

Retirement as an institution has interesting correlations with life span, especially in those countries where it is voluntary, and people are not forced into it, pushed out of their own lives by uncaring bureaucrats. More than one set of research results indicates that retirement is bad for health, and there is the suggestion that this might be because of declining physical activity. Certainly it is easy enough to point to correlations between ill health and retirement - people who age more rapidly or become ill and frail will certainly retire at much higher rates. Much of this research goes beyond the event of retirement itself to look at what happens later, however, and that is where suggested causation emerges from the data.

The open access paper I'll point out today might be taken to indicate that most earlier studies of this nature are perhaps overly simplistic. There are many life paths to consider: an obese individual who retires due to ill health is in a very different bracket of influences and outcomes from a thin individual who transitions from a desk job to actively gardening during the day. Some groups of people do actually undertake more physical activity following retirement. The paper itself splits out retirees into a fair number of categories, and it is worth looking through to find the tables and charts. What we might take away from this is a reminder that rejuvenation therapies are on the horizon, some already in early clinical development, and for many of us a few years here or a few years there may wind up being the difference between living to benefit or dying just at the verge of the new era of treatments for the causes of aging.

Does retirement mean more physical activity? A longitudinal study

Participation in physical activity declines with age concurrent to an increasing risk of preventable health conditions like type 2 diabetes. Yet physical activity is widely recognized as crucial for strengthening and maintaining physical and mental health during aging. Some transitions out of the labor market, such as retirement and semi-retirement, may free up time that could be used to (re) engage in physical activity. Retirement can be seen, therefore, as a potentially sensitive period in the lifecourse to target interventions for promoting healthy ageing. Evidence on physical activity during retirement from cross-sectional studies is mixed and limited by the spectre of reverse causality. Some longitudinal studies have the potential to approximate the transition to retirement, so should be regarded as higher quality evidence. Of the longitudinal studies, some have attempted to isolate the impact of retirement on leisure-time physical activity specifically. Others have investigated whether trajectories in physical activity across retirement vary by indicators of socioeconomic circumstances. Findings remain equivocal, however, providing no firm answer on how retirement affects participation in physical activity.

Accordingly, the purpose of this longitudinal study was to examine participation in different intensities of physical activity among people transitioning out of full-time employment to different forms of retirement, while also accounting for transitions to unemployment, part-time work, or disability status. Data was obtained for 5,754 people in full-time employment aged 50-75 from the US Health and Retirement Survey. Logistic regression was used to examine trajectories in twice-weekly participation in light, moderate and vigorous physical activity among those transitioning to part-time work, semi-retirement, full retirement, or economic inactivity due to disability, in comparison to those remaining in full-time employment.

Twice weekly participation in vigorous and light physical activity changed little for those who remained in full-time employment, while moderate physical activity decreased between baseline and follow-up. Differences in physical activity according to transitional categories at follow-up were evident. Baseline differences in physical activity across all intensities were greatest among participants transitioning from full-time to part-time employment compared to those who remained in full-time employment throughout the study period. Those transitioning to unemployment were already among the least physically active at baseline, irrespective of intensity. Those transitioning to full-time retirement were also among the least active. Declines in physical activity were reported for those transitioning to economic inactivity due to a disability. Physical activity increased regardless of intensity among participants transitioning to semi-retirement and full retirement. Light physical activity increased for those transitioning to unemployment, though less change was evident in moderate or vigorous physical activity.

Insufficient physical activity is suggested to cause 6% of coronary heart disease, 7% of type 2 diabetes, 10% of breast cancer, 10% of colon cancer, and 9% of premature mortality. Although finding opportunities to promote the initiation and maintenance of physically active lifestyles is needed across the lifecourse, this study supports previous evidence that indicates the process of retirement as one such time period. Inevitably, the findings raise questions and hypotheses requiring analyses that are beyond the remit of the paper and, in some cases, also the data available. For example, is the rise in physical activity regardless of intensity among people moving into semi-retirement due to less time spent in employment? Why are people who move into part-time work already more physically active than their counterparts who remained in full-time work? Is the rise in light physical activity among people who become unemployed sustained among those who re-enter some level of employment? What factors buffer the potential impact of disability on the substantial decreases in physical activity? What types of activities do people become more or less engaged in and are there differences between transitional groups? To what extent do changes in physical activity coinciding with the transition out of full-time employment reflect personal choices versus any number of possible competing demands upon time, including informal caring and volunteering? This is not an exhaustive list and it is clear that much remains unknown. Yet, the need to promote physical activity in ageing populations remains a pressing concern and these hypotheses warrant investigation in order to target future interventions accordingly.

A Smad7 Gene Therapy to Inhibit Age-Related Muscle Loss is in Development

There are always many ways to influence any specific process in cells and tissues. When it comes to enhanced muscle growth, the most popular approaches so far are myostatin inhibition, such as via gene knockout or the use of antibodies, or increased levels of the myostatin inhibitor follistatin. Both of these have been shown to greatly increase muscle mass in a number of species, and are thus potential treatments to compensate for the loss of muscle mass and strength that occurs over the course of aging. Physical weakness is a large component of age-related frailty, and even partially removing that part of the aging process is a worthy goal. The research group noted here has taken a different approach to this area of biochemistry, targeting smad7 to inhibit processes that break down muscle tissue:

"Chronic disease affects more than half of the world's population. It occurs with chronic infection, muscular dystrophy, malnutrition and old age. About half the people who die from cancer are actually dying from muscle wasting. What kills a lot of people isn't the loss of skeletal muscle but heart muscle. The heart literally shrinks, causing heart failure." In cachexia, tumors secrete hormones that cause muscle deterioration; in effect, the body eats its own muscles, causing weakness, frailty and fatigue. Researchers have long sought to stop this process, but failed to find a safe way. That's because the hormones that cause wasting - in particular, a naturally occurring hormone called myostatin - play important roles elsewhere in the body.

So researchers needed a way to stop myostatin, but only in muscles. Their solution: an adeno-associated virus - a benign virus that specifically targets heart and skeletal muscle. The virus delivers a small piece of DNA - a signaling protein called Smad7 - into muscle cells. Smad7 then blocks two signaling proteins called Smad2 and Smad3, which are activated by myostatin and other muscle-wasting hormones. By blocking those signals, Smad7 stops the breakdown of muscles. "Smad7 is the body's natural break and, by inhibiting the inhibitor, you build muscle." In 2015, the researchers launched AAVogen, a company that will develop this discovery into a commercial drug, AVGN7.

Link: https://news.wsu.edu/2016/07/26/scientist-develops-gene-therapy-muscle-wasting/

GPR17 as a Target to Reduce Measures of Aging in the Brain

Researchers here note that leukotriene receptor antagonists appear to reduce inflammation and increase plasticity in the brains of rats. They pin down the receptor GPR17 as a protein of interest in this effect. While not directly addressing underlying damage and change that causes inflammation and loss of neural plasticity, it is possible that this type of approach may produce sufficient benefits in humans to merit development. The same arguments apply here as for other classes of therapy that improve tissue maintenance without doing much to reduce the molecular damage that drives aging, such as stem cell transplants. There are clearly meaningful benefits in that case, and so long as this sort of research and development doesn't result in the abandonment of attempts to repair damage and thus halt and reverse aging, it is worth pursuing.

Counteracting some, or ideally all, of such age-related changes might rejuvenate the brain and lead to preservation or even improvement of cognitive function in the elderly. The feasibility of such an approach was recently demonstrated by experiments exposing the aged brain to a young systemic environment, that is, young blood, through heterochronic parabiosis. The aged brain responded to young blood by reduced microglia activation, enhanced neurogenesis, and importantly, by improved cognition. Vice versa, old blood caused premature ageing of the young brain and led to impaired cognition. A proteomic approach identified eotaxin, a chemokine involved in asthma pathology, as one of the molecules that is elevated in ageing and that contributes to neuroinflammation, reduced neurogenesis and to impaired cognition. This triggered us to hypothesize that, aside from eotaxin, additional mechanisms that are originally related to peripheral inflammatory conditions such as asthma might act or even be present in the central nervous system (CNS), where they potentially modulate degenerative and regenerative events.

Leukotriene signalling is well studied in the field of asthma. Leukotrienes mediate inflammatory reactions associated with increased vascular permeability, and leukotriene receptor antagonists such as the drug montelukast have been successfully developed to treat asthmatic patients. The role of leukotrienes in the brain, in particular their contribution to degeneration and regeneration, is less clear and sometimes even controversial. Nevertheless, elevated levels of leukotrienes were reported in acute as well as chronic CNS lesions, and also in the aged brain, where they might mediate neuroinflammatory responses including microglia activation. Here, we demonstrate that montelukast reduces neuroinflammation, restores blood-brain barrier integrity and increases neurogenesis specifically in the brain of old rats, the latter being mediated through inhibition of the GPR17 receptor. Most importantly, montelukast treatment restores cognitive function in the old animals, paving the way for future clinical translation for the treatment of dementias.

The effect on neurogenesis was, like the anti-inflammatory activity, specific to old rats. Thus, montelukast might stimulate neural progenitor proliferation only in situations in which neurogenesis is compromised. Montelukast might liberate progenitors from age-associated inhibitory mechanisms, which most likely include elevated levels of leukotrienes. Obviously, the extrapolation of these results from normal ageing to neurodegenerative diseases is intriguing, and some of the beneficial effects of montelukast in animal models of neurodegeneration might well be attributed to enhanced neurogenesis. In general, a clear dissection between neurogenesis- and neuroinflammation-mediated effects on cognition is not straightforward as neurogenesis and neuroinflammation strongly influence each other. For example neural progenitors induce microglia proliferation and activation, and vice versa, microglia regulate adult hippocampal neurogenesis.

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639806/

Exercise and TERRA in Telomere Biology

Occasionally I'll post research that is only tenuously relevant to aging, but nonetheless fascinating. That is the case for this article and open access paper on a fairly new and still poorly understood area of telomere biology. The researchers link exercise to the generation of TERRA, or telomeric repeat-containing RNA, which might lead to all sorts of speculation among long-time readers here. Exercise, telomere length, and aging are all in the same general bucket of items with many established links. Speculation is all that can be done by onlookers at the present time, however, given that the research community has yet to establish firm connections leading from TERRA to any of the behaviors of telomeres and, separately, exercise that are known to be relevant in aging. Still, reading through gives a good sense of just how complex the situation is under the hood. There are no simple relationships in biochemistry.

Telomeres are repeating DNA sequences that cap the ends of chromosomes. Every time a cell divides a little of the telomere is lost as the cell's DNA is replicated. When the remaining telomeres become too short the cell self-destructs or becomes senescent. This is a part of the Hayflick limit, which has evolved to ensure that most cells can only replicate so many times. Every tissue consisting of such limited cells is supported by a much smaller population of stem cells, which use telomerase to lengthen their telomeres and thus consistently produce an ongoing supply of new cells with long telomeres to replace those that reach their limits. The situation in which only some cells are privileged to divide indefinitely exists because it keeps cancer rates low enough for complex long-lived species to exist and evolve. These days telomere length and telomerase are hot topics in aging research, though not all of it is entirely justified to my eyes. Telomerase gene therapies have been shown to extend life in mice, which may be a result that works along the same lines as stem cell therapies, by increasing the activity of cells and maintenance of tissues. Average telomere length declines with age, but this is a statistical relationship across populations, of limited use for individual diagnosis. Telomere length seems very much like a marker and not a cause of aging.

Telomeres are DNA, and DNA encodes blueprints for proteins. A part of the process of gene expression by which proteins are created is transcription, wherein DNA is used as the pattern to produce RNA molecules. Are telomeres transcribed just like the rest of the nuclear DNA? Yes, as it turns out. Telomeric DNA is transcribed to produce TERRA molecules. What does TERRA do? That is an interesting question with few firm answers at the present time, but a lot of leads and maybes. Telomeres are not just passively sitting there: they encode for RNA, and that RNA does things. By linking TERRA to exercise, known to improve health via a variety of mechanisms, there is the thought that perhaps there are more direct connections than previously thought between changing telomere length and the various options like exercise and calorie restriction known to slow the progression of aging. It is particular interesting, for example, that TERRA may regulate the activity of telomerase, though as for much of the other results relating to TERRA this is fairly tentative and subject to revision. Is this all really relevant to the future of our lives, however? Probably not, as exercise, calorie restriction, and similar ways to modestly slow aging are not the gateways to human rejuvenation. They do too little to address the forms of damage that cause aging, and only repair of that damage, rather than merely slowing it down, can greatly extend life. But that said, this is a most interesting space in the study of cellular biology.

Exercise Boosts Telomere Transcription

When healthy individuals perform a cardiovascular workout, their muscles increase transcription of telomeres. A novel transcription factor appears to promote telomere transcription and provides the first direct evidence that telomere transcription is linked to exercise and metabolism in people. Telomeres were thought to be transcriptionally silent until several years ago when researchers found that mammalian telomeres, including human ones, are readily transcribed into telomeric repeat-containing RNA (TERRA). These RNA molecules have been shown to associate with telomeres but whether and how TERRA can protect telomeres - the repetitive sequences at the ends of linear chromosomes that form a sort of aglet to protect the structures - or promote the lengthening of the ends of chromosomes is not yet fully understood.

Researchers first analyzed human telomeric sequences for potential transcription factor binding sites. The researchers identified a potential binding site for the transcription factor nuclear respiratory factor 1 (NRF1), then confirmed its ability to bind the ends of chromosomes in human cancer cell lines. Because NRF1 is activated when stores of ATP are depleted, as during exercise, the team next enlisted 10 young and healthy volunteers to a low- or high-intensity workout on a stationary bicycle for 45 minutes. The researchers took muscle biopsies and blood samples prior to, right after, and 2.5 hours after the exercise. TERRA levels were increased 2.5 hours after both the low and high intensity workouts and were highest after the high intensity exercise. This is the first evidence that telomeres are transcribed in non-dividing human tissue. Exercise produces reactive oxidative species (ROS) that may damage telomeres. The researchers are now addressing the hypothesis that the TERRA molecules produced from NRF1-dependent telomere transcription may act as scavenger molecules that react with the ROS, protecting the telomere itself from oxidation. "As it is not yet established what role TERRA plays at mammalian telomeres, it is premature to speculate on the effect of NRF1 and TERRA upregulation in exercise on telomere biology or aging."

Nuclear respiratory factor 1 and endurance exercise promote human telomere transcription

DNA breaks activate the DNA damage response and, if left unrepaired, trigger cellular senescence. Telomeres are specialized nucleoprotein structures that protect chromosome ends from persistent DNA damage response activation. Whether protection can be enhanced to counteract the age-dependent decline in telomere integrity is a challenging question. Telomeric repeat-containing RNA (TERRA), which is transcribed from telomeres, emerged as important player in telomere integrity. However, how human telomere transcription is regulated is still largely unknown.

We identify nuclear respiratory factor 1 and peroxisome proliferator-activated receptor γ coactivator 1α as regulators of human telomere transcription. In agreement with an upstream regulation of these factors by adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK), pharmacological activation of AMPK in cancer cell lines or in normal nonproliferating myotubes up-regulated TERRA, thereby linking metabolism to telomere fitness. Cycling endurance exercise, which is associated with AMPK activation, increased TERRA levels in skeletal muscle biopsies obtained from 10 healthy young volunteers. The data support the idea that exercise may protect against aging.

More Details on SENS Research Foundation's ALT Cancer Program

The SENS Research Foundation is currently raising funds for the next step in its cancer research program: building one of the necessary foundations for a universal cancer therapy, one form of treatment that can in principle halt all types of cancer. This requires putting a stop to the lengthening of telomeres in cancer cells, as without that ability cancer tissue cannot grow and spread. This is the one actionable common mechanism shared by all cancers. Cancer cells can use telomerase or alternative lengthening of telomeres (ALT) to extend telomere length, and while some research groups are working on telomerase inhibition, it is unfortunately the case that very few people are working on ALT. Since it has been demonstrated in mice that telomerase cancers can become ALT cancers, both approaches are needed to build a truly universal cancer treatment. Thus the SENS team has stepped in to fill the gap, and needs our help to raise the funds to make this happen.

The Major Mouse Testing Program staff writers took the opportunity to catch up with SENS Research Foundation's Dr. Haroldo Silva who is leading the OncoSENS campaign seeking cures for ALT Cancer.

I saw the article "Control ALT, Delete Cancer" about this project that you co-wrote in April, 2015. Why are you only now starting the crowdfunding effort?

Because we are now at the point where our hard work paid off and we were able to overcome most of the technical hurdles associated with making our novel ALT-specific assay compatible with robotic/automation methods. This is essential to performing high-throughput and large-scale screening studies. We will be measuring a particular biomarker that has only been observed in ALT cancers, namely C-circles, which are circular pieces of DNA containing a repetitive sequence only found at the ends of chromosomes (i.e., telomeres). The more ALT activity is present in a given cancer, the higher the levels of C-circles present in them. Therefore, once we exposed the ALT cancer cells to different compounds we will measure C-circle content quickly to assess if any of the compounds was able to inhibit the ALT pathway.

If your screening does find a promising compound, what do you plan to do with it? Will you patent its anti-ALT properties?

After exhaustive validation of the initial positive screening results, the next step will depend on the nature of the particular compound. If it is currently used in patients for cancer or any other indications we could approach the company that commercializes it to start a joint development program focused on ALT cancer therapy. Otherwise we will explore alternative ways of moving the development of these potential therapies into the private sector. We will absolute aim to patent any compounds that we find helpful in the fight against cancer whenever possible. It takes an average of 12 years for a compound to go from discovery to clinical use in the US. Now, it is possible to reduce that time significantly in case the promising compound we find in our screening is either already approved for clinical use or has been through extensive clinical trials. We will be testing such compounds as part of our screening as explained above. Alternatively, we could target initially ALT cancers that affect less than 200,000 patients in the US in order to obtain orphan drug designation, which can significantly expedite the approval process. This would pave the way for bringing therapies to more common ALT cancers.

How many other groups have also looked at ways to inhibit ALT?

There are very few research groups performing ALT-related cancer research worldwide, especially when you compare it to the amount of scientific output from telomerase-based cancer research efforts. Even within the research groups dedicating a lot of resources to ALT research, none of them to the best of our knowledge have the technical capability to perform such a large small molecule screening in the way we are planning to do it. Our technological achievement with the C-circle assay puts our group in a unique position to perform the largest screening study ever attempted in the field of ALT cancer research.

Link: http://majormouse.org/?q=node%2F225

Stem Cell Therapy as a Potential Glaucoma Treatment

Researchers here provide evidence in mice to suggest that stem cell treatments could be used to address some forms of glaucoma, usually caused by an increase in pressure in the eye that can damage the optic nerve and other structures. The types of glaucoma of interest here are those in which the drainage channels for aqueous humour deteriorate, as those channels might be induced to regenerate via the transplantation of stem cells produced from the patient's own tissues:

Researchers injected stem cells into the eyes of mice with glaucoma. The influx of cells regenerated the tiny, delicate patch of tissue known as the trabecular meshwork, which serves as a drain for the eyes to avoid fluid buildup. When fluid accumulates in the eye, the increase in pressure could lead to glaucoma. The disease damages the optic nerve and can result in blindness. "We believe that replacement of damaged or lost trabecular meshwork cells with healthy cells can lead to functional restoration following transplantation into glaucoma eyes."

One potential advantage of the approach is that the type of stem cells used - called induced pluripotent stem cells - could be created from cells harvested from a patient's own skin. That gets around the ethical quandary of using fetal stem cells, and it also lessens the chance of the patient's body rejecting the transplanted cells. The researchers were able to get the stem cells to grow into cells like those of the trabecular meshwork by culturing them in a solution that had previously been "conditioned" by actual human trabecular meshwork cells. The researchers were encouraged to see that the stem cell injection led to a proliferation of new endogenous cells within the trabecular meshwork. In other words, it appears the stem cells not only survived on their own, but coaxed the body into making more of its own cells within the eye, thus multiplying the therapeutic effect. The team measured the effects in the mice nine weeks after the transplant. Lab mice generally live only two or three years, and nine weeks is roughly equal to about five or six years for humans.

The researchers say they are confident that their findings hold promise for the most common form of glaucoma, known as primary open angle glaucoma. They aren't sure yet if their mouse model is as relevant for other forms of the disease. Another possible limitation of the research: It could be that new trabecular meshwork cells generated from the stem cell infusion eventually succumb to the same disease process that caused the breakdown in the first place. This would require retreatment. It's unclear, though, whether an approach requiring multiple treatments over time would be viable. The researchers plan to continue studying the approach.

Link: http://www.research.va.gov/currents/0716-5.cfm

A Few of the More Interesting of Recent Alzheimer's Research Results

A large fraction of the public funding devoted to aging research goes towards Alzheimer's disease, a very broad set of initiatives that dovetail with other large investments in mapping and understanding the biochemistry of the brain. This is a diverse area of study, since it involves figuring out how a fair-sized slice of the brain actually works at the detail level in order to understand how it becomes broken in this particular case. This means that a great many papers and research results flow past on a weekly basis. Not all of them are useful; institutions of public funding always turn into jobs programs over time, and that inevitably means a lot of people working on things that are neither useful nor interesting. Further, these sorts of institutions are so risk averse that they essential stop funding true fundamental research, the high-risk search for new knowledge. To have a good shot at winning a grant from the National Institute on Aging you really have to be working on something that is already fairly well known and characterized - grant awarding bodies want to see little risk, and want to pay for an expected outcome. Which is the antithesis of actual research. This is why most of the important work at any given time, the real cutting edge in medical research, is funded by some combination of philanthropy and creative accounting by lab managers.

The nature of government programs is a big problem for any group that seeks to use the public funding mainstream as a guide to what they should be doing to help things move faster in the field. If you simply follow that lead, you wind up like the Ellison Medical Foundation, spending a lot of money on fundamental research to no good end, with very little in the way of practical outcomes to show for it at the end of the day. The National Institute on Aging playbook includes a large amount of waste and make-work, and all too little in the way of earnestly pushing the bounds of the possible. In this day and age, an era of rapid progress in biotechnology and medicine, both pushing the bounds of the possible and practical outcomes should be high on the priority list for aging research, meaning radically better and more effective ways to treat aging and age-related disease. Still, there is a lot of Alzheimer's research underway, and some of it is interesting, potentially useful, or at the very least not make-work. A few recent examples can be found below.

Scientists discover how proteins in the brain build-up rapidly in Alzheimer's

Fibrils, known as amyloids, become intertwined and entangled with each other, causing the so-called 'plaques' that are found in the brains of Alzheimer's patients. Spontaneous formation of the first amyloid fibrils is very slow, and typically takes several decades, which could explain why Alzheimer's is usually a disease that affects people in their old age. However, once the first fibrils are formed, they begin to replicate and spread much more rapidly by themselves, making the disease extremely challenging to control.

Despite its importance, the fundamental mechanism of how protein fibrils can self-replicate without any additional machinery is not well understood. Researchers found that the seemingly complicated process of fibril self-replication is actually governed by a simple physical mechanism: the build-up of healthy proteins on the surface of existing fibrils. The researchers used a molecule known as amyloid-beta, which forms the main component of the amyloid plaques found in the brains of Alzheimer's patients. They found a relationship between the amount of healthy proteins that are deposited onto the existing fibrils, and the rate of the fibril self-replication. In other words, the greater the build-up of proteins on the fibril, the faster it self-replicates. They also showed, as a proof of principle, that by changing how the healthy proteins interact with the surface of fibrils, it is possible to control the fibril self-replication. "This discovery suggests that if we're able to control the build-up of healthy proteins on the fibrils, we might be able to limit the aggregation and spread of plaques."

Antibiotic treatment weakens progression of Alzheimer's disease through changes in the gut microbiome

Two of the key features of Alzheimer's disease are the development of amyloidosis, accumulation of amyloid-ß (Aß) peptides in the brain, and inflammation of the microglia, brain cells that perform immune system functions in the central nervous system. Buildup of Aß into plaques plays a central role in the onset of Alzheimer's, while the severity of neuro-inflammation is believed to influence the rate of cognitive decline from the disease. For this study, researchers administered high doses of broad-spectrum antibiotics to mice over five to six months. At the end of this period, genetic analysis of gut bacteria from the antibiotic-treated mice showed that while the total mass of microbes present was roughly the same as in controls, the diversity of the community changed dramatically. The antibiotic-treated mice also showed more than a two-fold decrease in Aß plaques compared to controls, and a significant elevation in the inflammatory state of microglia in the brain. Levels of important signaling chemicals circulating in the blood were also elevated in the treated mice.

While the mechanisms linking these changes is unclear, the study points to the potential in further research on the gut microbiome's influence on the brain and nervous system. "We don't propose that a long-term course of antibiotics is going to be a treatment - that's just absurd for a whole number of reasons. But what this study does is allow us to explore further, now that we're clearly changing the gut microbial population and have new bugs that are more prevalent in mice with altered amyloid deposition after antibiotics."

Pim1 inhibition as a novel therapeutic strategy for Alzheimer's disease

Clinically, Alzheimer's disease (AD) is characterized by impairments of memory and cognitive functions. Accumulation of amyloid-β (Aβ) and neurofibrillary tangles are the prominent neuropathologies in patients with AD. Strong evidence indicates that an imbalance between production and degradation of key proteins contributes to the pathogenesis of AD. The mammalian target of rapamycin (mTOR) plays a key role in maintaining protein homeostasis as it regulates both protein synthesis and degradation. A key regulator of mTOR activity is the proline-rich AKT substrate 40 kDa (PRAS40), which directly binds to mTOR and reduces its activity. Notably, AD patients have elevated levels of phosphorylated PRAS40, which correlate with Aβ and tau pathologies as well as cognitive deficits. Physiologically, PRAS40 phosphorylation is regulated by Pim1, a protein kinase of the proto-oncogene family. Here, we tested the effects of a selective Pim1 inhibitor (Pim1i), on spatial reference and working memory and AD-like pathology in 3xTg-AD mice.

We have identified a Pim1i that crosses the blood brain barrier and reduces PRAS40 phosphorylation. Pim1i-treated 3xTg-AD mice performed significantly better than controls. Additionally, 3xTg-AD Pim1i-treated mice showed a reduction in soluble and insoluble Aβ40 and Aβ42 levels, as well as a 45.2% reduction in Aβ42 plaques within the hippocampus. Furthermore, phosphorylated tau immunoreactivity was reduced in the hippocampus of Pim1i-treated 3xTg-AD mice by 38%. Mechanistically, these changes were linked to a significant increase in proteasome activity. These results suggest that reductions in phosphorylated PRAS40 levels via Pim1 inhibition reduce Aβ and Tau pathology and rescue cognitive deficits by increasing proteasome function. Given that Pim1 inhibitors are already being tested in ongoing human clinical trials for cancer, the results presented here may open a new venue of drug discovery for AD by developing more Pim1 inhibitors.

Brain cell death in Alzheimer's linked to structural flaw

Studying cells from postmortem brains of people who had Alzheimer's disease, researchers previously found that areas of DNA that are typically tightly wound in the cell's nucleus are instead relaxed and unwound in brain cells from Alzheimer's patients. When DNA is unwound it can switch on genes that should be turned off. In the new study, the researchers took a closer look at the nuclei of Alzheimer's patients' brain cells to find out how the DNA becomes unwound. When the researchers used a very high-resolution microscopy technique that let them observe the entire nucleus, they were surprised to see tunnels running through the nucleus of brain cells from people with Alzheimer's disease that were not seen in normal brain cells. "We wanted to find out if these tunnels were actually causing neurons to die or whether they were a side effect of the disease. Using the fly model of Alzheimer's disease we genetically blocked the process of tunnel formation and found that indeed less brain cells died and the flies lived longer. We are now performing lab experiments to see if we can also block the process using drugs."

After identifying this first potential new drug target, the researchers continued their experiments to further elucidate this biological pathway. The cell nucleus is surrounded by what is known as the lamin nucleoskeleton, a structural scaffold made of the protein lamin. They found that when the lamin nucleoskeleton is disrupted and tunnels form, the DNA inside can no longer anchor to the nucleoskeleton and becomes unraveled. In other words, the interaction between tightly wound DNA and the nucleoskeleton is required to maintain the overall 3D architecture of the DNA. They also discovered that the tau that aggregates in the brains of people with Alzheimer's disease disrupts the lamin nucleoskeleton by overstabilizing the actin cytoskeleton found outside of the nucleus, in the cell's cytoplasm. This interrupts the normal coupling between the actin cytoskeleton and the lamin nucleoskeleton, which, in turn, causes the tightly wound DNA to relax. This causes genes to turn on that are not supposed to and, consequently, brain cells die.

Progress in the Use of Bioscaffolds for Muscle Regeneration

Researchers have demonstrated some restoration of strength in patients with severe muscle injuries, using scaffold materials derived from the extracellular matrix (ECM) of pig tissues. This is an incremental step forward towards the end goal of complete regeneration, but shows the potential utility of suitable guide materials to spur reconstruction of missing tissues. This has some relevance to the issue of age-related loss of muscle mass and strength; many of the approaches used to regenerate severe muscle injuries may see adaptation to restoration of muscle in the elderly, though for preference not those involving surgical procedures.

For the Muscle Tendon Tissue Unit Repair and Reinforcement Reconstructive Surgery Research Study, 11 men and two women who had lost at least 25 percent of leg or arm muscle volume and function first underwent a customized regimen of physical therapy for four to 16 weeks. Researchers then surgically implanted a "quilt" of compressed ECM sheets designed to fill in their injury sites. Within 48 hours of the operation, the participants resumed physical therapy for up to 24 additional weeks. By six months after implantation, patients showed an average improvement of 37.3 percent in strength and 27.1 percent in range of motion tasks compared with pre-operative performance numbers. CT or MRI imaging also showed an increase in post-operative soft tissue formation in all 13 patients.

The new data builds upon a 2014 study that showed damaged leg muscles grew stronger and showed signs of regeneration in three out of five men whose old injuries were surgically implanted with ECM derived from pig bladder. Those patients also underwent similar pre- and post-operative physical therapy. The recent results included more patients with varying limb injuries; used three different types of pig tissues for ECM bioscaffolds; investigated neurogenic cells as a component of the functional remodeling process; and included CT and MRI imaging to evaluate the remodeled muscle tissue. "The three different types of matrix materials used all worked the same, which is significant because it means this is a generic property of these materials and gives the surgeons a choice for using whichever tissue they like."

Link: http://www.upmc.com/media/NewsReleases/2016/Pages/regenerative-medicine-muscle-injuries.aspx

Nanog May Improve Function of Old Stem Cells

In this research, the scientists involved investigate a potential role for the gene nanog in the aging of stem cells, a prospect that has been studied for a few years now. Nanog is involved in pluripotency, the ability of embryonic stem cells to generate any cell type, but, as is the case for most cellular biology, not in a straightforward way. In recent years, with the development of induced pluripotent stem cells, a great deal of attention has been directed towards the molecular biology of genes such as nanog.

To battle aging, the human body holds a reservoir of nonspecialized cells that can regenerate organs. These cells are called adult stem cells, and they are located in every tissue of the body and respond rapidly when there is a need. But as people age, fewer adult stem cells perform their job well, a scenario which leads to age-related disorders. Reversing the effects of aging on adult stem cells, essentially rebooting them, can help overcome this problem.

In the new study, researchers introduced Nanog into aged smooth muscle stem cells and found that Nanog opens two key cellular pathways: Rho-associated protein kinase (ROCK) and Transforming growth factor beta (TGF-β). In turn, this jumpstarts dormant proteins (actin) into building cytoskeletons that adult stem cells need to form muscle cells that contract. Force generated by these cells ultimately helps restore the regenerative properties that adult stem cells lose due to aging.

Additionally, the researchers showed that Nanog activated the central regulator of muscle formation, serum response factor (SRF), suggesting that the same results may be applicable for skeletal, cardiac and other muscle types. The researchers are now focusing on identifying drugs that can replace or mimic the effects of NANOG. This will allow them to study whether aspects of aging inside the body can also be reversed. This could have implications in an array of illnesses, everything from atherosclerosis and osteoporosis to Alzheimer's disease.

Link: http://www.buffalo.edu/news/releases/2016/07/023.html

Towards a Greater Knowledge of Mitochondrial DNA Damage in Aging

Today I'll point out a very readable scientific commentary on mutations in mitochondrial DNA (mtDNA) and the importance of understanding how these mutations spread within cells. This is a topic of some interest within the field of aging research, as mitochondrial damage and loss of function is very clearly important in the aging process. Mitochondria are, among many other things, the power plants of the cell. They are the evolved descendants of symbiotic bacteria, now fully integrated into our biology, and their primary function is to produce chemical energy store molecules, adenosine triphosphate (ATP), that are used to power cellular operations. Hundreds of mitochondria swarm in every cell, destroyed by quality control processes when damaged, and dividing to make up the numbers. They also tend to promiscuously swap component parts among one another, and sometimes fuse together.

Being the descendants of bacteria, mitochondria have their own DNA, distinct from the nuclear DNA that resides in the cell nucleus. This is a tiny remnant of the original, but a very important remnant, as it encodes a number of proteins that are necessary for the correct operation of the primary method of generating ATP. DNA in cells is constantly damaged by haphazard chemical reactions, and equally it is constantly repaired by a range of very efficient mechanisms. Unfortunately mitochondrial DNA isn't as robustly defended as nuclear DNA. Equally unfortunately, some forms of mutation, such as deletions, seem able to rapidly spread throughout the mitochondrial population of a single cell, even as they make mitochondria malfunction. This means that over time a growing number of cells become overtaken by malfunctioning mitochondria and fall into a state of dysfunction in which they pollute surrounding tissues with reactive molecules. This can, for example, increase the level of oxidized lipids present in the bloodstream, which speeds up the development of atherosclerosis, a leading cause of death at the present time.

The question of how exactly some specific mutations overtake a mitochondrial population so rapidly is still an open one. There is no shortage of sensible theories, for example that it allows mitochondria to replicate more rapidly, or gives them some greater resistance to the processes of quality control that normally cull older, damaged mitochondria. The definitive proof for any one theory has yet to be established, however. In one sense it doesn't actually matter all that much: there are ways to address this problem through medical technology that don't require any understanding of how the damage spreads. The SENS Research Foundation, for example, advocates the path of copying mitochondrial genes into the cell nucleus, a gene therapy known as allotopic expression. For so long as the backup genes are generating proteins, and those proteins make it back to the mitochondria, the state of the DNA inside mitochondria doesn't matter all that much. Everything should still work, and the present contribution of mitochondrial DNA damage to aging and age-related disease would be eliminated. At the present time there are thirteen genes to copy, a couple of which are in commercial development for therapies unrelated to aging, another couple were just this year demonstrated in the lab, and the rest are yet to be done.

Still, the commentary linked below is most interesting if you'd like to know more about the questions surrounding the issue of mitochondrial DNA damage and how it spreads. This is, as noted, a core issue in the aging process. The authors report on recent research on deletion mutations that might sway the debate on how these mutations overtake mitochondrial populations so effectively.

Expanding Our Understanding of mtDNA Deletions

A challenge of mtDNA genetics is the multi-copy nature of the mitochondrial genome in individual cells, such that both normal and mutant mtDNA molecules, including selfish genomes with no advantage for cellular fitness, coexist in a state known as "heteroplasmy." mtDNA deletions are functionally recessive; high levels of heteroplasmy (more than 60%) are required before a biochemical phenotype appears. In human tissues, we also see a mosaic of cells with respiratory chain deficiency related to different levels of mtDNA deletion. Interestingly, cells with high levels of mtDNA deletions in muscle biopsies show evidence of mitochondrial proliferation, a compensatory mechanism likely triggered by mitochondrial dysfunction. In such circumstances, deleted mtDNA molecules in a given cell will have originated clonally from a single mutant genome. This process is therefore termed "clonal expansion."

The accumulation of high levels of mtDNA deletions is challenging to explain, especially given that mitophagy should provide quality control to eliminate dysfunctional mitochondria. Studies in human tissues do not allow experimental manipulation, but large-scale mtDNA deletion models in C. elegans have proved to be helpful, showing some conserved characteristics that match the situation in humans, as well as some divergences. Researchers have used a C. elegans strain with a heteroplasmic mtDNA deletion to demonstrate the importance of the mitochondrial unfolded protein response (UPRmt) in allowing clonal expansion of mutant mtDNAs to high heteroplasmy levels. They demonstrate that wild-type mtDNA copy number is tightly regulated, and that the mutant mtDNA molecules hijack endogenous pathways to drive their own replication.

The data suggests that the expansion of mtDNA deletions involves nuclear signaling to upregulate the UPRmt and increase total mtDNA copy number. The nature of the mito-nuclear signal in this C. elegans model may have been the transcription factor ATFS-1 (activating transcription factor associated with stress-1), which fails to be imported by depolarized mitochondria, mediates UPRmt activation by mtDNA deletions. A long-standing hypothesis proposes that deleted mtDNA molecules clonally expand because they replicate more rapidly due to their smaller size. To address this question, researchers examined the behavior of a second, much smaller mtDNA deletion molecule. They found no evidence for a replicative advantage of the smaller genome, and clonal expansion to similar levels as the larger deletion. In human skeletal muscle, mtDNA deletions of different sizes also undergo clonal expansion to the same degree. Furthermore, point mutations that do not change the size of the total mtDNA molecule also successfully expand to deleterious levels, indicating that clonal expansion is not driven by genome size. Thus, similar mechanisms may be operating across organisms. In the worm, this involves mito-nuclear signaling and activation of the UPRmt.

There is some debate over interpretation of results. One paper indicates that UPRmt allows the mutant mtDNA molecules to accumulate by reducing mitophagy. Another demonstrates that the UPRmt induces mitochondrial biogenesis and promotes organelle dynamics (fission and fusion). Both papers show that by downregulating the UPRmt response, mtDNA deletion levels fall, which may allow a therapeutic approach in humans. Could there be a similar mechanism in humans, especially since some features detected in C. elegans are also present in human tissues, including the increase in mitochondrial biogenesis and the lack of relationship between mitochondrial genome size and expansion? It is likely that there will be a similar mechanism to preserve deletions since, as in the worm, deletions persist and accumulate in human tissues, despite an active autophagic quality-control process. Although the UPRmt has not been characterized in humans as it has in the worm, and no equivalent protein to ATFS-1 has been identified in mammals, proteins such as CHOP, HSP-60, ClpP, and mtHSP70 appear to serve similar functions in mammals as those in C. elegans and suggest that a similar mechanism may be present.

Further Investigation of P21 and SDF-1 Shows that Cxcr4 Inhibitors can Promote Scarless Healing in Mammals

Mice lacking p21 can regenerate small wounds without scarring, something that is not normally possible in adult mammals. Separately, SDF-1 has been identified as a signal to recruit and activate stem cells, and efforts are underway build regenerative therapies on this basis. Here, scientists dig further into the intersection of these two lines of research to find - as in other studies - that immune system involvement seems to be key to the process. They show that an existing class of drug can induce healing of minor injuries without scars in mice by blocking some of the immune cell activities that normally take place in mammalian wound healing. Ultimately, the goal in this and a range of similar research is to establish whether or not our biochemistry is capable of salamander-like regeneration of limbs and organs, and if so which of the numerous differences between highly regenerative and less regenerative species are blocking this ability.

The ability to regenerate lost organs following trauma is one of the great unsolved mysteries in medical research, and understanding the basis of mammalian regenerative biology is relevant to human regenerative medicine. In mammals, traumatic injuries typically heal with a fibroblast- and collagen-rich response, producing a fibrous scar rather than full reconstitution of cellular subtypes and functional tissue architecture. A central focus of regenerative and developmental biology is to restore normal tissue structure and function after injury. Astonishing examples of tissue and organ regeneration following injury include appendage and eye regeneration in amphibians and teleosts. Limited examples of tissue regeneration also exist in mammals, suggesting that mechanisms governing tissue regeneration may be evolutionarily conserved. Here, we investigated mouse ear regeneration to identify cellular, genetic, and signaling mechanisms driving mammalian appendage regeneration.

Mice lacking p21 fully regenerate injured ears without discernable scarring. Here we show that, in wild-type mice following tissue injury, stromal-derived factor-1 (Sdf1) is up-regulated in the wound epidermis and recruits Cxcr4-expressing leukocytes to the injury site. In p21-deficient mice, Sdf1 up-regulation and the subsequent recruitment of Cxcr4-expressing leukocytes are significantly diminished, thereby permitting scarless appendage regeneration.

The hypothesis that wound epidermis initiates or regulates tissue regeneration has been suggested in other species. In salamanders, the absence of the wound epidermis prevents limb regeneration. Deer antlers regenerate annually, but antlerogenesis is lost if the skin overlying the antler bone pedicle is removed and replaced with a full-thickness skin graft. These findings suggest a two-way interaction between the overlying skin and underlying skeletal tissues and cell types to coordinate tissue regeneration. Our identification of p21-dependent Sdf1 production by keratinocytes at the wounded edge is consistent with this possibility. Further localization of this effect may benefit from studies of mice with conditional p21 knockout alleles, when available. How multiple tissue-specific precursor cells expand and collaborate to restore integrated tissue architecture and function also remains to be defined.

While immune cell recruitment is required to initiate early wound-healing responses, previous studies have demonstrated that some forms of immunosuppression can accelerate subsequent regeneration. In humans, fetal skin regenerates after injury without scarring (unlike adult wound healing), a phenomenon accompanied by reduced immune cell infiltration and decreased inflammation. In our studies, we found that decreased Sdf1 expression and diminished recruitment of Cxcr4+ leukocytes promote tissue regeneration. The balance between inflammatory responses and tissue regeneration is likely to be complex and multiphasic. Further studies are needed to investigate the subsets of wound Cxcr4+ leukocytes recruited by Sdf1 and understand how these cells normally promote wound healing, fibrosis, and scar formation.

Using AMD3100, an established antagonist of Cxcr4 signaling, we induced appendage regeneration in wild-type animals. In the past, AMD3100, either by itself or in combination with platelet-derived growth factor or tacrolimus, improved wound healing and scar formation in diabetic mice and mice receiving thermal burns. Here we show that AMD3100 treatment promotes tissue regeneration and restores normal tissue structure and function after injury in a scarless manner. Currently, short courses of AMD3100 are used to mobilize bone marrow stem cells for transplantation in humans, and a common side effect of AMD3100 is peripheral blood leukocytosis. We speculate that the peripheral blood leukocytosis seen in patients may also result from disruption of Sdf1-mediated leukocyte trafficking, and future studies are needed to understand this mechanism more precisely. Collectively, our observations suggest that the clinical uses of AMD3100 may be expanded to include treatment of traumatic appendage wounds or chronic nonhealing wounds in skin. These are common problems that lack effective treatments and represent an important unmet need in current clinical practice.

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4617975/

Use of Stem Cells in Bypass Therapy Reduces Scarring and Mortality

The press here reports on the positive results of a recent small trial of the introduction of stem cells during bypass surgery for heart attack survivors. Stem cell therapies have over the past decade demonstrated highly variable outcomes in patients, and the methodology of delivery has been shown to be very important. A fair amount of the work accomplished in this field over the past fifteen years has involved trying to determine why seemingly similar approaches to the use of stem cells in regenerative medicine can produce both very successful and marginal outcomes. This therapy, for example, isn't all that different from others that have failed to move the needle in heart regeneration.

People suffering from heart disease have been offered hope by a new study that suggests damaged tissue could be regenerated through a stem cell treatment injected into the heart during surgery. The small-scale study followed 11 patients who during bypass surgery had stem cells injected into their hearts near the site of tissue scars caused by heart attacks. One of the trial's most dramatic results was a 40% reduction in the size of scarred tissue. Such scarring occurs during a cardiac event such as a heart attack, and can increase the chances of further heart failure. The scarring was previously thought to be permanent and irreversible.

At the time of treatment, the patients were suffering heart failure and had a very high (70%) annual mortality rate. But 36 months after receiving the stem cell treatment all are still alive, and none have suffered a further cardiac event such as a heart attack or stroke, or had any readmissions for cardiac-related reasons. Twenty-four months after participants were injected with the stem cell treatment there was a 30% improvement in heart function, 40% reduction in scar size, and 70% improvement in quality of life, as judged by the Minnesota living with heart failure (MLHF) score. "It's an early study and it's difficult to make large-scale predictions based on small studies. But even in a small study you don't expect to see results this dramatic. These are 11 patients who were in advanced heart failure, they had had a heart attack in the past, multiple heart attacks in many cases. The life expectancy for these patients is less than two years, we're excited and honoured that these patients are still alive." The next study will include a control group who undergo bypass but do not receive stem cell treatment, to measure exactly what impact the treatment has.

Link: https://www.theguardian.com/science/2016/jul/24/stem-cell-trial-suggests-damaged-heart-tissue-regenerated

Another Set of Popular Science Articles on the Prospects for Aging Research

Science News recently lumped together a few popular science articles on aging research into a special issue on the subject. As the blurb notes, aging is very much neglected in comparison to its importance, and accepted despite the damage it does. Defeating aging should be the primary focus of medical research, given that it kills about twice as many people as all of the other causes of death put together, and is the root cause of an even larger proportion of disability, pain, suffering, and medical expense. That it isn't is just another sign that we humans are not good at priorities and common sense.

Everyone ages. Growing old is a fundamental feature of human existence. But, our scientific understanding of aging pales in comparison to its significance in our lives. While new studies reveal exciting prospects for slowing the effects of aging, its causes and extensive effects remain enigmatic. Scientists are still divided on some fundamentals of aging, and that's why aging research raises some interesting questions. For example, how does it change the brain? How did different life histories evolve? How old is the oldest blue whale? This special report addresses those questions and more.

I'll link to the first of the articles below, and leave an exploration of the others as an exercise for the reader. That first article is a fairly standard example of this sort of thing, covering a few recent and more publicly discussed research initiatives in the field. As is usually the case, it largely focuses on ways to modestly slow aging, such as calorie restriction mimetic research, or to spur greater stem cell activity in old individuals, such as some of the leads resulting from parabiosis research. It omits any explicit mention of the SENS approach to rejuvenation research, which is, sadly, still par for the course, even as it examines some of the current progress in senescent cell clearance, a topic that has been on the SENS list for fifteen years at this point. That was a decade in advance of any meaningful attempts to remove senescent cells in the laboratory, and it is worth recalling that, as for other aspects of SENS, this was mocked within the scientific community at the time. Those who said as much back then now largely pretend that they agreed this was a viable approach all along; such is human nature. The SENS vision for medical control of aging hasn't changed, and is well known in the field now, but still working its way to greater material support. So when a journalist calls up half a dozen researchers to chat about their research the odds are still pretty good that none of those worthies will have any aspect of the presently active SENS programs in his or her list of pet topics.

This is unfortunate, as it means that most popular science journalism continues to propagate an unrealistic view of the near future of aging research, especially when it comes to expectations for the odds of greatly extending the healthy human life span. There is an opportunity to be seized here, a way to build rejuvenation therapies that can extend life to a far greater extent than is possible via approaches such as calorie restriction mimetics, trials of drugs like metformin, or other marginal strategies that aim to alter the operation of metabolism so as to slightly slow aging. Putting SENS repair strategies like senescent cell clearance side by side with calorie restriction mimetics is to create a false equivalence - these things are not the same at all. Repair can in principle create rejuvenation and indefinite healthy life spans, only limited by the quality of the repair implementation. All of these other technologies to slightly slow aging can do no such thing: they are very limited in comparison, and even if perfected can at most add a few years to human life spans. There is a huge difference between repairing the damage that causes aging and merely slowing down the accumulation of that damage, and that difference is being ignored by people who should know better. Why does this matter? Because building the rejuvenation therapies envisaged in great detail in the SENS proposals, some of which are coming into being in a few startup companies at the present time, requires large-scale support: money, advocacy, discussion, and most importantly widespread understanding.

A healthy old age may trump immortality

On the inevitability scale, death and taxes are at the top. Aging is close behind. It's unlikely that scientists will ever find a way to avoid death. And taxes are completely out of their hands. But aging, recent research suggests, is a problem that science just might be able to fix. As biological scientists see it, aging isn't just accumulating more candles on your birthday cake. It's the gradual deterioration of proteins and cells over time until they no longer function and can't replenish themselves. In humans, aging manifests itself outwardly as gray hair, wrinkles and frail, stooped bodies. Inside, the breakdown can lead to diabetes, heart disease, cancer, Alzheimer's disease and a host of other problems.

Scientists have long passionately debated why cells don't stay vigorous forever. Research in mice, fruit flies, worms and other lab organisms has turned up many potential causes of aging. Some experts blame aging on the corrosive capability of chemically reactive oxygen molecules or "oxidants" churned out by mitochondria inside cells. DNA damage, including the shortening of chromosome endcaps (called telomeres) is also a prime suspect. Chronic, low-grade inflammation, which tends to get worse the older people get, wreaks so much havoc on tissues that some researchers believe it is aging's prime cause, referring to aging as "inflammaging." All these things and more have been proposed to be at the root of aging.

Some researchers, like UCLA's Steve Horvath, view aging as a biological program written on our DNA. He has seen evidence of a biological clock that marks milestones along life's path. Some people reach those milestones more quickly than others, making them older biologically than the calendar suggests. Others take a more leisurely stroll, becoming biological youngsters compared with their chronological ages. Many others, including Richard Miller, a geroscientist at the University of Michigan, deny that aging is programmed. Granted, a biological clock may measure the days of our lives, but it's not a ticking time bomb set to go off on a particular date. After all, humans aren't like salmon, which spawn, age and die on a schedule. Instead, aging is a "by-product of running the engine of life," says biodemographer Jay Olshansky of the University of Illinois at Chicago. Eventually bodies just wear out. That breakdown may be predictable, but it's not premeditated.

Despite all the disputes about what aging is or isn't, scientists have reached one radical consensus: You can do something about it. Aging can be slowed (maybe even stopped or reversed). But exactly how to accomplish such a counterattack is itself hotly debated. Biotechnology and drug companies are developing several different potential remedies. Academic scientists are investigating many antiaging strategies in animal experiments. (Most of the research is still being done on mice and other organisms because human tests will take decades to complete). Even researchers who think they have finally come up with real antiaging elixirs say they don't have the recipe for immortality, though. Life span and health span, new research suggests, are two entirely separate things. Most researchers who work on aging aren't bothered by that revelation. Their goal is not necessarily extending life span, but prolonging health span - the length of time people live without frailty and major diseases.

The glass half full view, to counter my glass half empty points above, is that one of the SENS approaches to treating the causes of aging has finally taken wing and left the nest in these past few years. Senescent cell clearance now appears in popular science articles, is worked on by a number of unaffiliated research groups, has demonstrated life extension in mice, and is under clinical development in multiple companies. As removal of senescent cells proves its worth, other lines of SENS research, other forms of damage to be repaired to create rejuvenation, and the overall strategic approach of focusing on damage and its repair, will gain greater support.

Killifish in Aging Research

Most aging research starts in short-lived species far removed from our own in the tree of life. There is a trade-off involved: it is much cheaper to explore and experiment with interventions in aging in a short-lived species, but the more distant the species the less likely that the results will be useful for longer-lived mammals. Fortunately many of the fundamental mechanisms relevant to aging are very similar across most of the animal kingdom, and even between yeast and humans. Low-cost exploration is very necessary in a field with little funding and an enormous, complex problem space. Without the use of flies, worms, and other short-lived species, most aging research would simply never happen. In recent years killifish have been inducted into the list of species used for aging research, which is an involved process in and of itself. This article looks at some of the high points:

Of the many varieties of killifish, the turquoise killifish (Nothobranchius furzeri) has the shortest lifespan - the briefest of any vertebrate bred in captivity, ranging from 3 to 12 months depending on strain and living conditions. Using killifish to study ageing is not a new idea. In the late twentieth century, scientists studied ageing in one species, Nothobranchius guentheri, that lives for about 14 months. But given techniques available at the time, they could come up with only basic descriptions of ageing features. Now, however, advances in molecular analysis have set up excellent conditions in which to develop the model and investigate mechanisms behind its dotage. The killifish's brief lifespan, relative to those of longer-lived models such as mice and zebrafish, enables ageing research to progress apace. And because the fish is a vertebrate, the research is more directly relevant to people than are studies of short-lived organisms such as fruit flies or nematodes.

The ephemeral existence that so appeals to scientists is an evolutionary adaptation to the fish's natural environment: their accelerated development enables them to live and reproduce in transient mud pools during the wet season in equatorial Africa. But that begged another question: would killifish age in a way that parallels the human process? The answer is yes: the fish do get 'old' before they die. Having shown that killifish decline with age, scientists now want to understand how the process occurs. One key resource is the collection of several strains from Africa whose genomes are not identical. By cross-breeding two strains, researchers created fish with a range of lifespans. They then compared the genomes and longevities of parent and second-generation progeny, and identified a few chromosomal regions, each with hundreds of genes that might influence ageing. Although these did not directly reveal genes involved in longevity, they suggested possible candidates. From this study, the scientists estimated that about 32% of variation in lifespan among turquoise killifish results from genetics, a figure comparable to the 20-35% estimated genetic contribution in mice.

Link: http://dx.doi.org/10.1038/535453a

AUF1 Linked to Stem Cell Function and Muscle Regeneration

The stem cells responsible for muscle growth and regeneration are perhaps the best studied of such populations. It seems that most of the new and interesting insights into the nuts and bolts of stem cell biology are coming from this part of the field, in any case. The therapies emerging from research along these lines should include ways to restore the diminished activity of stem cells in older people, with effects most likely similar to present stem cell therapies, but with greater control and selectivity in outcomes. In particular, researchers are very interesting in finding ways to boost muscle growth in older people in order to compensate for the characteristic loss of muscle mass and strength that occurs with aging.

Researchers found that levels of a single protein known as AUF1 determine whether pools of stem cells retain the ability to regenerate muscle after injury and as mice age. Changes in the action of AUF1 have also been linked by past studies to human muscle diseases. More than 30 genetic diseases, collectively known as myopathies, feature defects in this regeneration process and cause muscles to weaken or waste away. Clinical presentation and age of diagnosis vary, but "this work places the origin of certain muscle diseases squarely within muscle stem cells, and shows that AUF1 is a vital controller of adult muscle stem cell fate."

The study results revolve around one part of gene expression, in which the instructions encoded in DNA chains for the building of proteins are carried by intermediates known as messenger RNAs (mRNAs). Proteins comprise the body's structures, enzymes and signals. The expression of certain genes that need to be turned on and off quickly is controlled in part by the targeted destruction of their mRNA intermediates, a job assigned to proteins like AUF1. The investigators found that among the functions controlled by mRNA stability is the fate of stem cells. Following skeletal muscle injury, muscle stem cells receive a signal to multiply and repair damaged tissue, a process that the researchers found is controlled by AUF1. Among the mRNA targets of AUF1 in muscle stem cells, they discovered one that encodes a "master regulator" of adult muscle regeneration, a protein known as MMP9. This enzyme breaks down other proteins, ultimately controlling their expression levels.

The investigators showed that they could restore normal muscle stem cell function and related muscle regeneration in mice lacking AUF1 by repurposing a drug developed for cancer treatment that blocks MMP9 activity. "This provides a potential path to clinical treatments that accelerate muscle regeneration following traumatic injury, or in patients with certain types of adult onset muscular dystrophy. We may be able to treat a variety of degenerative diseases by enhancing resident tissue stem cells through targeting MMP9 and its pathways, even those with normal AUF1."

Link: http://www.eurekalert.org/pub_releases/2016-07/nlmc-gcr072016.php

Effective Therapies to Extend Healthy Life May Well be Widely Available for a Decade or More in Advance of Definitive Proof

Five years from now, it will be possible to take a trip overseas to have most of the senescent cells that have built up in your tissues cleared away via some form of drug or gene therapy treatment. That will reduce your risk of suffering most age-related diseases, and in fact make you measurably younger - it is a narrow form of rejuvenation, targeting just one of the various forms of cell and tissue damage that cause aging, age-related disease, and ultimately death. I say five years and mean it. If both of the present senescent cell clearance startup companies Oisin Biotechnologies and UNITY Biotechnology fail rather than succeed, and it is worth noting that the Oisin founders have a therapy that actually works in animal studies, while drugs and other approaches have also been shown to both clear senescent cells and extend life in mice, then there will be other attempts soon thereafter. The basic science of senescent cell clearance is completely open, and anyone can join in - in fact the successful crowdfunding of the first Major Mouse Testing Program study earlier this year was exactly that, citizen scientists joining in to advance the state of the art in this field.

Five years from now, however, there will be no definitive proof that senescent cell clearance extends life in humans, nor that it reduces risk of age-related disease in our species over the longer term. There will no doubt be a few more studies in mice showing life extension. There will be initial human evidence that clearance of senescent cells causes short-term improvements in technical biomarkers of aging such as DNA methylation patterns, or more easily assessed items such as skin condition - given how much of the skin in old people is made up of senescent cells - or markers of chronic inflammation. These are all compelling reasons to undertake the treatment, but if you want definite proof of life extension you'll have to wait a decade or more beyond the point of first availability, as that is about as long as it takes to put together and run academic studies that make a decent stab at quantifying effects on mortality in old people.

Uncertainty is the state of affairs when considering the effects of potentially life-extending therapies on human life span. Consider the practice of calorie restriction, for example, where theory suggests the likely outcome is a few extra years, but certainly not a large number of extra years or else it would be very apparent in epidemiological data. I think that an enterprising individual could, given a good relationship with the Calorie Restriction Society, put together a 20-year or 40-year study to that would - in theory - produce a decent set of data on practitioners and outcomes in the wild. It won't happen, most likely, because for one the funding isn't there for such a study, and secondly we'll be well into the era of widely available rejuvenation therapies along the way. Those calorie restriction practitioners will be taking advantage of treatments to repair the causes of aging just like everyone else.

Further, consider the possible effects of bisphosphonate treatment. There is some suggestion that this could add five years to life expectancy, a huge effect to go otherwise unnoticed for a treatment that quite a lot of people undergo in old age - but that may be exactly what has happened, for all we know. There is little work on replication or investigation, sadly. I point this out as an example of the degree to which uncertainty can and does exist for human data, as well as just how hard and expensive it is to dispel. It would take a large study, a lot of work, and waiting for a decade or so to figure out whether this bisphosphonate effect is real.

Now, consider that five years of additional life is not so far off a realistic expectation for the first prototype of any SENS-style rejuvenation therapy, such as senescent cell clearance, that repairs just one of the forms of damage that cause aging. Fixing one thing only gets you so far, as all the other forms of damage will still, on their own, kill you. Aubrey de Grey of the SENS Research Foundation believes that only small gains in overall life span are possible without addressing all of the causes of aging. This is a position well supported by statistical evidence for what would happen if, say, all cardiovascular disease or all cancer was eliminated without affecting other age-related disease. Only a few years of life expectancy would be gained in either of those cases. Arguments against that position run along the lines of suggesting that any repair of damage should produce incremental increases in life span, with reference to reliability theory, or that since all forms of damage and disease interact with one another, removing one will tend to slow the others. But we really won't know for sure until these therapies are out there in use and data is being gathered. You can only go so far in mice, especially given that their life spans are very much more plastic in response to circumstances than ours.

The reason I point out all of this is to note that the next couple of decades are going to be an increasingly confusing time for people who want to purchase elective therapies to extend healthy life. Things that actually work to a significant degree are going to be available alongside increasingly effective stem cell therapies and the same old garbage from the "anti-aging" marketplace that does absolutely nothing but part fools from their money. There will be infinite shades of grey between all of those things. You only have to look at the opportunists selling supposed longevity-enhancing supplements today based on calorie restriction mimetic research, and the articles in which that research is presented as equivalent and equal to SENS rejuvenation research approaches such as clearing senescent cells, to see how this is going to go. To navigate this near future market, for the decade or two it will take for the approaches that actually work to definitively prove their worth in human studies, you must understand more of the underlying science. You must be able to explain to yourself why damage repair approaches like those of the SENS portfolio are more likely to be effective than calorie restriction mimetic supplements - in short, your participation in the market will be guided by your take on the science. This is far from an academic exercise; time matters greatly.

Tissue Engineering of Liver Organoids

Researchers have demonstrated the ability to build organoids of many different tissue types, starting with just a cell sample. The open access paper linked here is one example of many at the present time. These organoids are tiny sections of functional or partially functional organ tissue, limited in size because the research community has yet to develop a reliable means of incorporating the intricate branching vasculature needed to support thicker and larger masses. Still, this is enough to build useful products, either for research such as drug development or even for transplantation in some cases. For organs that are essentially chemical factories, that function doesn't require the original organ to be exactly replicated in shape and size - transplanting a few dozen organoids grown from the patient's own cells might be good enough to form the basis for a viable therapy.

The idea to construct in vitro 3D tissue-like structures to be used as model system for the respective organ is an appealing experimental approach. The main focus hereby is to exploit the in vivo physiological mechanism that occurs during organ development or healing (regeneration) and to implement similar mechanisms to develop a functional tissue in vitro. Such 3D liver-like structures would for example meet the needs of the pharmacological and toxicological industry for drug screening. The main techniques to generate 3D cellular constructs are either the formation of spheroids or building of tissue-like structures by placing sheets of cells and extracellular matrix components on top of each other. The disadvantage of spheroids is that the cells are distributed randomly without formation of spatial organization i.e., liver spheroids neither possess typical hepatic cord-like alignment of polarized hepatocytes nor sinusoids lined with endothelial cells reflecting the in vivo situation. Similarly, 3D liver models generated using sandwich cultures can never fully recapitulate the true in vivo architecture of the organ. Such ex vivo formation of tissue for most complex organs such as heart, kidney or brain would be very challenging.

However, the liver is exceptional in its ability to regenerate. It is well established that fully differentiated adult liver is capable of regeneration as long as a sufficient amount of intact liver remains after damage. Therefore, in principle any differentiated adult liver cell should harbor the potential to proliferate and regenerate to a complex and functional organ under suitable conditions. Indeed, induced-pluripotent stem cells (iPSC) stimulated to become hepatic endoderm-like cells (iPSC-HE) together with mesenchymal stem cells (MSC) and human umbilical vein endothelial cells (HUVEC), self-organize in vitro into macroscopically visible 3D cell clusters by an intrinsic organizing capacity. When these structures were transplanted into mice, they became vascularized, engrafted into the recipient's tissue and produced hepatic factors like albumin. Possible applications of such an organoid structure include replacement therapy but also the possibility to study hepatotoxic effects of new compounds. They could as well be used as simplified model system to investigate processes like liver regeneration, fibrogenesis or malignant transformation. Due to the fact that these organoids are formed out of different cell types, which are in 3D contact to each other, they can be expected to represent a system which is much closer to the depicted in vivo situation than conventional approaches.

In the present work we analyzed if liver organoids could also be generated from adult, differentiated cells and if these organoids can be cultured for long-term to study liver functions. Instead of stem cells, hepatocytes were used to reflect the parenchymal cells of the liver. In order to depict the native physiological condition of liver, we further used liver sinusoidal endothelial cells (LSECs) instead of conventional endothelial cells like HUVECs. LSECs are a specialized type of scavenger endothelial cells that are able to endocytose an array of physiological and foreign macromolecules and colloids from the blood. The generation of these cells involves stable transduction of primary cells with lentiviral constructs carrying sequences which code for certain proliferation-inducing factors. These cells are cultured in medium containing a defined mixture of growth factors, allowing tighter control over proliferation (up to 40 population doublings). Employing this process, almost unlimited numbers of cells from one donor can be obtained. Our results show that liver organoids can be generated and these organoids after culturing them for a period of 10 days, express several marker proteins, genes and enzymes to a degree that is comparable to adult human liver. Furthermore, the architecture of these liver organoids to some degree resembles typical hepatic structures.

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4619350/

Most People will be Surprised by Dramatic Increases in Human Longevity Due to the Introduction of Rejuvenation Therapies Over the Next Forty Years

Most people and most organizations consider the present to be a good model for the future, and base long-term plans on present trends. They are always surprised by change, despite living in an era characterized by rapid change driven by technological progress. The present slow upward trend in remaining human life expectancy at age 65 - perhaps a year every decade - is not the result of any deliberate effort to intervene in the aging process. It is a byproduct of general improvements in the medical technology that is used to attempt to patch over the consequences of aging at the late stage: efforts to keep a damaged machine running without fixing the damage, in other words. This is challenging and expensive, but nonetheless as biotechnology advances small gains are achieved. How very much faster and more effective will this be when the research community redirects its attention to the causes of aging? That is the question, and it isn't hard to see that there is a world of difference between repairing the damage that causes dysfunction and ignoring that damage.

Yet most people don't pay attention to what is going on in the lab, to what is under development in startups, or to what the scientific community is saying, but rather only to existing products that are widely available and well advertised. As a consequence they will be surprised, and potentially unprepared to take advantage of new options that can actually achieve rejuvenation to some degree. Retirement will be transformed radically by rejuvenation biotechnology within our lifetimes. New therapies that collectively add decades to life by repairing the damage that causes aging - an option unavailable today - will certainly be a reality in the 2030s, since the first are in clinical development today. You won't hear any of this from the mainstream of financial planning, as illustrated in this article, but as it is reasonably priced rejuvenation therapies and continued participation in the workforce may be the only good option for many people given the absence of savings in most societies today:

First, you were supposed to die at 85. Then 90. Now 95 and even 100 are common defaults when financial planners tell people how much to save for retirement. Except that's nuts. In the U.S., the typical man at age 65 is expected to live another 18 years. The typical woman, about 20. Yet many financial planners contend we should save as if we're all going to be centenarians. That notion so offends adviser Carolyn McClanahan that she confronted a speaker at a financial planning conference who contended that death at 100 should be the default assumption. "Even when you have a 350-pound guy who smokes?" says McClanahan. Advances in medical science "aren't happening that fast."

Some saving is essential. Obviously. But saving for a retirement that ends at age 100 means you'll need a nest egg that's about 40 percent larger than what you'd need for a normal life expectancy. While there's a 70 percent chance that at least one member of a married couple will make it to 85, the odds are only 20 percent either partner will make it to 95, and even lower that anyone will see 100. "Most of our improvements in life expectancy are coming from the decline in child mortality. The actual survival rate of people in their 80s and 90s is not increasing very fast."

If a 35-year-old wanted to replace 60 percent of her current $60,000 salary at age 65, she would need about $1.2 million at retirement age if she expects to live to 85. Stretch that to 100, and she'll need about $1.7 million. (These figures assume 3 percent average annual inflation and a 7 percent return on investments. Your mileage may vary.) Currently most workers (54 percent) have less than $25,000 saved for retirement. Uncertainty about longevity is just one of many unknowns in financial planning, says Bob Veres, a financial planning industry consultant. So-called "safe" withdrawal rates of 4 percent annually may actually be too conservative in most markets. Also, people often spend less as they age, which makes planners' typical assumptions that spending will increase with inflation each year too conservative. Cautious assumptions may stave off lawsuits, Veres says, but they "diminish the spending capacity of people who retire today."

Link: http://www.cbsnews.com/news/should-you-save-enough-to-live-to-100/