Correlating Cytomegalovirus, T Cell Senescence, and Arterial Stiffness in Aging

Today I'll point out a paper that links three fairly long-standing topics in aging research: the role of cytomegalovirus infection in immune system aging, cellular senescence in the immune system, and progressive stiffening of blood vessels. The authors point out correlations rather than uncovering specific mechanisms to link these items, but it fits nicely with a range of other research on senescent T cells, ways in which senescent cells could contribute to loss of vascular elasticity, the decline of the aging immune system, and the intricate relationship between tissue maintenance and immune system activity. Disarray in regeneration is linked closely with disarray in the immune system, particularly the chronic inflammation that occurs with age. To complete the circle, in any scenario involving inflammation in aging, we nowadays have to pull in the topic of senescent cells for consideration. These cells are efficient generators of inflammatory signaling, and this appears to be a primary mechanism by which they cause harm.

Blood vessel stiffness is one of the most consequential aspects of aging. Cardiovascular disease vies with cancer for the most prevalent cause of death in our species. Stiffness in blood vessels produces hypertension, which in turn contributes to the remodeling of heart tissue that leads to heart failure. Hypertension and stiffness also increase the pace at which small vessels rupture in the brain, and other delicate organs such as the kidney, raising the pace of damage in those tissues. Finding ways to maintain blood vessel elasticity would go a long way to reduce the incidence of numerous classes of age-related disease.

Where does cytomegalovirus fit into this? This is a herpesvirus that is present in near everyone by the time old age rolls around. It is largely harmless to most people, at least in the short term, but over the long term the immune system just keeps on throwing resources at cytomegalovirus in a futile attempt to get rid of it. In an aged immune system a vast number of cells are uselessly specialized to cytomegalovirus, rather than being available for other tasks. The rate of replacement of immune cells is low in adults, and even lower in the elderly, and thus the immune system cannot recover from a state in which most active immune cells are not performing as they should. At least not without some form of outside intervention yet to be brought to the clinic, such as regeneration of the thymus, or regular infusions of patient matched immune cells grown from skin samples.

A correlation between the degree to which the immune system is engaged in its eternal losing battle with cytomegalovirus and the number of senescent T cells suggests a causal relationship, though given the present state of the field I think that a decent argument could be made for the arrow of causation to point in either direction. Are those elders most afflicted by cytomegalovirus afflicted because the immune system was already in a state of accelerated decline for other reasons, or is cytomegalovirus the cause of that decline? From historical data and comparisons between regions of today's diverse world we know that a greater burden of infectious disease has a negative impact on life expectancy. So it is tempting to look first for cytomegalovirus to be the cause, but biology is rarely as consistent as we'd like it to be.

Arterial Stiffness Is Associated With Cytomegalovirus-Specific Senescent CD8+ T Cells

Growing evidence from recent animal and human studies suggests that T cells contribute to the development of hypertension. Previously, we demonstrated that hypertensive patients have an increased frequency of replicative senescent CD8+ T cells in peripheral blood; these cells are characterized by the loss of CD28 and the acquisition of CD57 on their surface. CD28 loss in T cells is one of the most prominent changes associated with aging in humans and is caused by the repetitive antigenic stimulation of T cells. CD57 expression is known to occur during the late stage of T-cell differentiation and might be a distinct measure of replicative senescence in T cells. Compared with CD28+ or CD57- T cells, CD28null or CD57+ T cells produce more proinflammatory cytokines and exert greater cytotoxicity. These senescent T cells are known to be associated with various inflammatory diseases in humans including cardiovascular disease.

It has been also known that cytomegalovirus infection is involved in the accumulation of CD28null or CD57+ senescent T cells. In humans, cytomegalovirus is known to be one of the most important antigens for repetitive T-cell stimulation, and latent infection with cytomegalovirus has been shown to strongly exert age-associated changes on peripheral T cell homeostasis. The cytomegalovirus-seropositive population has a higher frequency of CD28null or CD57+, replicative senescent T cells than the cytomegalovirus-seronegative population. Moreover, cytomegalovirus infection is associated with a variety of chronic inflammatory processes in cardiovascular disease such as hypertension. However, it has not been elucidated how cytomegalovirus infection and senescent T cells contribute to the pathogenesis of cardiovascular disease.

Increased arterial stiffness is one of the major mechanisms underlying the pathogenesis of hypertension. Arterial stiffness is increased in the presence of conventional cardiovascular risk factors including aging. The degree of arterial stiffness is known to be associated with various markers of inflammation, suggesting that immune responses likely play a role in increasing arterial stiffness. Therefore, we investigated whether T-cell senescence is associated with arterial stiffness in the general population, as assessed using pulse wave velocity (PWV) measurements. Next, considering the antigen reactivity of senescent T cells, we examined cytomegalovirus-specific T-cell response and analyzed the relationship between these results and the degree of arterial stiffness.

The study population consisted of 415 Koreans who were recruited from subjects initially registered in the Yonsei Cardiovascular Genome cohort. Our findings demonstrate that the frequency of senescent CD8+CD57+ T cells in peripheral blood is independently correlated with arterial stiffness. Cytomegalovirus-specific T-cell responses were analyzed because cytomegalovirus is a major driving antigen for replicative senescence in T cells. We found that cytomegalovirus-specific CD8+ T cells were more frequently observed in the CD57+ population, and cytomegalovirus-specific cytokine secretion and the cytotoxic degranulation of CD8+ T cells were independently associated with PWV. These data suggest that immune aging, especially T-cell senescence that is linked to cytomegalovirus infection, might play a role in the progression of vascular aging.

Induced Pluripotent Stem Cell Therapy in a Primate Model of Parkinson's Disease

Cell therapy continues to be a promising approach to establishing a treatment for Parkinson's disease. The intent is to replace the dopamine-generating neurons that are lost as the condition progresses. Researchers here report on the past few years of a cell transplant study carried out in monkeys made to exhibit the same cell loss that is produced by Parkinson's in humans. Unlike earlier efforts, the researchers here are using induced pluripotent stem cells in order to generate the neurons to be transplanted.

One of the last steps before treating patients with an experimental cell therapy for the brain is confirmation that the therapy works in monkeys. Researchers have now shown that monkeys with Parkinson's disease symptoms show significant improvement over two years after being transplanted neurons prepared from human induced pluripotent stem cells (iPS cells). The study is expected to be a final step before the first iPS cell-based therapy for a neurodegenerative disease.

Parkinson's disease degenerates a specific type of cells in the brain known as dopaminergic (DA) neurons. It has been reported that when symptoms are first detected, a patient will have already lost more than half of his or her DA neurons. Several studies have shown the transplantation of DA neurons made from fetal cells can mitigate the disease. The use of fetal tissues is controversial, however. On the other hand, iPS cells can be made from blood or skin, which is why researchers plan to use DA neurons made from iPS cells to treat patients.

To test the safety and effectiveness of DA neurons made from human iPS cells, researchers transplanted the cells into the brains of monkeys. It is generally assumed that the outcome of a cell therapy will depend on the number of transplanted cells that survived, but the researchers found this was not the case. More important than the number of cells was the quality of the cells. "Each animal received cells prepared from a different iPS cell donor. We found the quality of donor cells had a large effect on the DA neuron survival." To understand why, he looked for genes that showed different expression levels, finding 11 genes that could mark the quality of the progenitors. One of those genes was Dlk1. "We are investigating Dlk1 to evaluate the quality of the cells for clinical applications."

Another feature of the study that is expected to extend to clinical study is the method used to evaluate cell survival in the host brains. The study demonstrated that magnetic resonance imaging (MRI) and position electron tomography (PET) are options for evaluating the patient post surgery. The group is hopeful that it can begin recruiting patients for this iPS cell-based therapy before the end of next year.


Protein Synthesis Differences in Progeria Suggest Changes in the Nucleolus as a Potential Biomarker of Aging

Researchers here note changes in the nucleolus in both old cells and cells from progeria patients, and suggest that these changes may be characteristic enough in normal aging to serve as a biomarker to assess biological age. There is great interest in the research community in establishing a low-cost, reliable biomarker of this nature, as it would considerably speed up the assessment of potential rejuvenation therapies, those that address the root causes of aging. Currently it is an expensive and time-consuming process, as studies must run long enough to observe the results of a treatment upon mortality rates.

Progeria is not accelerated aging, but has superficially similar outcomes. This rare condition is of interest because the form of molecular damage that is prevalent in this condition, mutated lamin A that causes structural and other irregularities in cells, is also found to a small degree in normal aging. It is an open question as to whether or not that matters in comparison to the laundry list of other forms of molecular damage found in old tissues. So secondary effects observed in progeria patients, those downstream of the lamin A issue, may well not be in any way relevant to normal aging. Even if the observation dovetails with existing knowledge, as is the case here, it could still be peculiar to the progeroid tissue environment and its particular distribution of forms of cellular damage, and so caution is required. Still, the findings in normal cells carried out as a part of this study are intriguing.

Scientists have found that protein synthesis is overactive in people with progeria. The work adds to a growing body of evidence that reducing protein synthesis can extend lifespan - and thus may offer a useful therapeutic target to counter both premature and normal aging. "The production of proteins is an extremely energy-intensive process for cells. When a cell devotes valuable resources to producing protein, other important functions may be neglected. Our work suggests that one driver of both abnormal and normal aging could be accelerated protein turnover."

Initially, researcher were interested in whether mutation was making the lamin A protein less stable and shorter lived. After measuring protein turnover in cultured cells from skin biopsies of both progeria sufferers and healthy people, she found that it wasn't just lamin A that was affected in the disease. "We analyzed all the proteins of the nucleus and instead of seeing rapid turnover in just mutant lamin A and maybe a few proteins associated with it, we saw a really broad shift in overall protein stability in the progeria cells. This indicated a change in protein metabolism that we hadn't expected."

Along with the rapid turnover of proteins, the team found that the nucleolus, which makes protein-assembling structures called ribosomes, was enlarged in the prematurely aging cells compared to healthy cells. Even more intriguing, the team found that nucleolus size increased with age in the healthy cells, suggesting that the size of the nucleolus could not only be a useful biomarker of aging, but potentially a target of therapies to counter both premature and normal aging. The work supports other research that appears in the same issue showing that decreasing protein synthesis extends lifespan in roundworms and mice. The researchers plan to continue studying how nucleolus size may serve as a reliable biomarker for aging.


Restoring Osteocalcin Reverses Memory Loss in Old Mice

Last year researchers showed that raising levels of osteocalcin in old mice reverses some of the age-related decline in exercise capacity. In the paper noted here, the same research group shows that increased osteocalcin also reverses some of the loss in memory function that takes place in later life, at least in mice. Taken together these are quite interesting demonstrations, and we might speculate on whether this could be a cause of improvements in the health of old mice obtained via heterochronic parabiosis, wherein the circulatory systems of an old and a young mouse are linked together. Osteocalcin levels decline with age, and in the osteocalcin studies, the increase in old mice provided by the simple approach of injection. So it doesn't seem implausible that parabiosis might increase the level of osteocalcin in the old mouse.

Currently there is some debate over how benefits emerge from the process of parabiosis. A recent study provided very good evidence to suggest that benefits occur due to a dilution of harmful factors in old blood rather than by provision of helpful factors from young blood. The studies of GDF11 levels that kicked off current interest in parabiosis are still being debated back and forth: it remains unclear as to whether the identification of GDF11 as a protein of interest is correct. So on the whole matters are still in flux in this area of study. That the researchers here produce benefits with plasma transfusion from young to old mice, something that has also had mixed evidence to date, is particularly interesting.

Back to osteocalcin; if researchers can find ways to produce some degree of benefit with supplementation of a few strategic circulating proteins, then all to the good. This nonetheless strikes me as adjusting downstream consequences of the root causes of aging - tinkering with the broken machinery to try to force it to behave rather than fixing the actual problem. Why do circulating protein levels change? They change because cells react to the accumulation of molecular damage in cells and tissues. That damage is the actual problem, and we should expect to find that repair or removal of the damage will revert changes in protein levels such as decline in osteocalcin. Given the advent of senolytic therapies to clear senescent cells - one form of repair treatment for a cause of aging - we should see that phenomenon begin to be cataloged in studies conducted over the next few years. Perhaps not for osteocalcin, depending on which form of damage causes this reaction, but certainly for some other changes.

Bone-Derived Hormone Reverses Age-Related Memory Loss in Mice

"In previous studies, we found that osteocalcin plays multiple roles in the body, including a role in memory. We also observed that the hormone declines precipitously in humans during early adulthood. That raised an important question: Could memory loss be reversed by restoring this hormone back to youthful levels? The answer, at least in mice, is yes, suggesting that we've opened a new avenue of research into the regulation of behavior by peripheral hormones."

Researchers conducted several experiments to evaluate osteocalcin's role in age-related memory loss. In one experiment, aged mice were given continuous infusions of osteocalcin over a two-month period. The infusions greatly improved the animals' performance on two different memory tests, reaching levels seen only in young mice. The same improvements were seen when blood plasma from young mice, which is rich in osteocalcin, was injected into aged mice. In contrast, there was no memory improvement when plasma from young mice engineered to be osteocalcin-deficient was given to aged mice. But adding osteocalcin to this plasma before injecting it into the aged mice resulted in memory improvement. The researchers also used anti-osteocalcin antibodies to deplete the hormone from the plasma of young mice, reducing their performance on memory tests.

The researchers then determined that osteocalcin binds to a receptor called Gpr158 that is abundant in neurons of the CA3 region of the hippocampus, the brain's memory center. This was confirmed by inactivating hippocampal Gpr158 in mice and subsequently giving them infusions of osteocalcin, which failed to improve their performance on memory tests. The researchers did not observe any toxic effects from giving the mice osteocalcin. "It's a natural part of our body, so it should be safe. But of course, we need to do more research to translate our findings into clinical use for humans."

Gpr158 mediates osteocalcin's regulation of cognition

That osteocalcin (OCN) is necessary for hippocampal-dependent memory and to prevent anxiety-like behaviors raises novel questions. One question is to determine whether OCN is also sufficient to improve these behaviors in wild-type mice, when circulating levels of OCN decline as they do with age. Here we show that the presence of OCN is necessary for the beneficial influence of plasma from young mice when injected into older mice on memory and that peripheral delivery of OCN is sufficient to improve memory and decrease anxiety-like behaviors in 16-month-old mice.

A second question is to identify a receptor transducing OCN signal in neurons. Genetic, electrophysiological, molecular, and behavioral assays identify Gpr158, an orphan G protein-coupled receptor expressed in neurons of the CA3 region of the hippocampus, as transducing OCN's regulation of hippocampal-dependent memory in part through inositol 1,4,5-trisphosphate and brain-derived neurotrophic factor. These results indicate that exogenous OCN can improve hippocampal-dependent memory in mice and identify molecular tools to harness this pathway for therapeutic purposes.

Envisaging Alzheimer's Disease as a Cascade from Amyloid to Inflammation to Tau

Alzheimer's disease is marked by an accumulation of solid deposits of amyloid-β and modified tau protein. It is also an inflammatory condition, like many age-associated diseases, and past evidence suggests that reduced inflammation can improve matters, while greater levels of chronic inflammation are a risk factor for developing Alzheimer's. What is cause and what is consequence in all of this, however? The authors of this study propose that the order of causation is amyloid, inflammation, then tau. If so, then amyloid clearance therapies should be better than anti-inflammatory strategies, as and when they can be made to work effectively in humans.

In the brains of people with Alzheimer's disease, there are abnormal deposits of amyloid beta protein and tau protein, and swarms of activated immune cells. But scientists do not fully understand how these three major factors combine to drive the disease. Researchers exposed immune cells normally found in an activated, inflammatory state in Alzheimer's brains to tiny clusters of amyloid beta - or oligomers, which are believed to be the most harmful forms of the protein. "Our thinking was that the amyloid beta oligomers would activate an inflammatory response in these immune cells, and we wanted to see if this would induce pathological forms of tau when given to neurons."

The researchers then focused on the fluid in which the immune cells had been growing. This fluid, which was filled with inflammatory factors resembled the fluid in which these cells typically live inside human brains. The team added this fluid to cultures of human cortical neurons. The neurons soon developed abnormal, bead-like swellings along their axons and dendrites. This "neuritic beading" has been seen in Alzheimer's patients and has been considered an early sign of neuronal damage, although it hasn't been clear how beading was connected to abnormal tau or if the beading led to Alzheimer's disease. The team then looked for tau in the beads and found a striking accumulation of it, though it was in an abnormal form, modified in a different way than previously thought. This modification is thought by the researchers to cause tau to become aggregated.

The finding of abnormal tau in the neuritic beads indicated that these beads could mark tau's entry into the Alzheimer's disease process. Within the beads, researchers also found high calcium levels, which are known to harm neurons and are considered an important feature of neurons in people with Alzheimer's. "We think these neuroinflammatory factors trigger this cascade. They flood the neuron with calcium. And we think that once the calcium accumulates, it causes tau to become abnormally modified. This probably leads to a snowball effect: tau detaches from microtubules and is trafficked throughout the neuron, ending up in these beads. One possibility is that these tau-filled beads are the sites where the classic tangle-like aggregates of tau will eventually emerge, which is the hallmark of Alzheimer's disease."

Researchers used mass spectrometry to sort out the amyloid beta-induced neuroinflammatory molecules that had triggered the calcium influx and neuritic beading. They were able to show that one protein in particular, MMP-9, was responsible for some of these adverse effects. "MMP-9 is an inflammatory protein shown to be elevated in the brains of Alzheimer's patients. In our study, we show that MMP-9 alone can trigger a calcium influx that floods the neuron." The researchers also identified the protein HDAC6, which originates from within neurons and concentrates in the neuritic beads. Normally, HDAC6 is thought to detect unwanted protein aggregates within neurons and transport them away for disposal. However, blocking HDAC6 stopped nearly all beads from forming in these experiments. Both of these proteins have been found to be elevated in affected areas of Alzheimer's brains. Drug companies are now developing and testing HDAC6 inhibitors, which have performed surprisingly well in early studies, although it has not been fully understood how these inhibitors work. "Our work might explain why HDAC6 inhibitors have shown such early promise."


The Society for the Rescue of our Elders

The Society for the Rescue of our Elders initiative arises from the same circle of people who run the Life Extension Foundation and the RAAD festival, and is one of the more promising items I've seen emerge from that group. If they put their minds to it, they should be well able to run useful human trials of senolytic drug candidates and a range of other nascent rejuvenation therapies as these treatments emerge - trying all of the more reliable and useful treatments from mouse studies in human volunteers in order to accelerate progress.

My complaint in the past has been that their efforts get corrupted by their supplement business, and other forms of useless nonsense, but so far that isn't visible here. It is certainly possible to argue the utility of some of the proposed trials, my usual complaints about SENS damage repair to reverse aging on the one side versus tinkering with metabolism to slightly slow aging on the other, but they're all backed by research groups in one way or another. While this particular initiative isn't quite ready for widespread attention yet, there is a signup form, and there is a contact email address if you have thoughts or offers of support to convey. For my part, I am certainly willing to participate in a sensibly designed senolytics trial, should the opportunity arise at a reasonable cost, and I'm sure many of the folk in the audience here are of much the same opinion.

The Society for the Rescue of our Elders has no bylaws, incorporating documents, or other legal structure. Its sole purpose is to unite people in ways that will accelerate the availability of rejuvenation technologies to benefit all of humanity, including members of the group. The Society for the Rescue of our Elders consists of about 1,000 individuals who have demonstrated their desire to donate, invest, and/or actively participate in advancing human age reversal studies.

The Society for the Rescue of our Elders is similar to groups formed in the past to advance a science when the medical profession showed little interest. In 1767 a few wealthy and civic-minded citizens in Amsterdam gathered to form the Society for Recovery of Drowned Persons. Amsterdam is a city of canals and hence people fell in and drowned. It thus became the birthplace for the teaching and promotion of the resuscitation of dead persons. The Society for Recovery of Drowned Persons introduced scientific principles and techniques. Following successes of the Amsterdam society, rescue societies sprang up in most European capitals in the 18th century, all with the goal of finding a way of successfully resuscitating victims of sudden death. Many of these techniques (or variations of them) are used in modern emergency medical practice."

Our mission is to demonstrate statistically-significant human age reversal so that an eruption of charitable and capitalistic forces will compete to induce even longer, healthier lifespans. We live in an era whereby limitations on maximum lifespans are likely to be soon vanquished. Each day our research is delayed, we grow older and frail. There is tremendous urgency to move human rejuvenation projects forward. Funding has been secured for some clinical studies. The costs of certain projects, however, will require them to be self-funded. In these cases, each study subject will have to pay their portion of expenses of being part of the study.

The dasatinib/quercetin study of senolytics therapy will commence shortly and funding was provided by a long-time Life Extension Foundation supporter. It is divided into three phases to test different dose timing. Phase One is now fully enrolled, but other phases are still enrolling subjects. Participants can travel to Los Angeles or Idaho and must be available for two weekends in a row.

The NAD+ infusion study has commenced and funding has been secured to cover 100% of this study's cost. This study is fully enrolled. Future studies that will test NAD+ infusions for Parkinson's, Alzheimer's, and stroke patients, are being planned. Let us know if you'd like to participate. The rapamycin study site has been moved to Southern California. Funding has been secured to cover 100% of this study's cost. The primary cost of this and some other studies are the extensive clinical and biomarker measures that must be done to assess if biological age reversal is occurring. Enrollment for this study is currently open.

The GDF11 trial is planned to initiate in Nassau, Bahamas around October of this year and will require each study participant to self-fund $7,800 for one year's treatment, which includes costs of extensive clinical and biomarker measurements. A clinical trial studying the immunomodulatory properties and cost-effectiveness of mesenchymal stem cells as an alternative treatment for chronic autoimmune conditions is commencing.

The thymus regeneration study will be based in California but is available nationwide. The cost to participate in a one-year trial will be a maximum of $28,000, which includes medications, MRI scans of the thymus (optional), and high-tech monitoring of immune status. The expected re-growth of the thymus gland (based on preliminary results from a 10-patient pilot study) may provide immune restoration benefits.

Young plasma transfer studies (also called Therapeutic Plasma Exchange) will initially be conducted at several sites in Florida, North Carolina, Colorado and Southern California. We anticipate more sites in the U.S. later this year. Two treatment protocols will be offered, one using 5% albumin and immune senescence markers will be offered in both protocols. The expected cost for six infusions including comprehensive measurements of possible efficacy is estimated at $50,000.


Crowdfunding Initial Development of MouseAGE, a Visual Biomarker of Aging for Mice

The latest crowdfunding project now running at is an interesting initiative to apply machine learning methods to generate a cost-effective biomarker of aging in mice based on image analysis rather than physical samples. The biomarker will then be released for free and open use by research groups. There is a need for ways to easily assess the biological rather than chronological age of subjects in laboratory studies, where biological age reflects the current level of damage, dysfunction, and mortality risk. Aging is a process based on the accumulation of molecular damage and its consequences, but until fairly recently there were no useful tests to reliably assess the current state of aging - to obtain a better, more comprehensive, and repeatable measure than just looking at skin condition, or grip strength, or any of the other simple assessments used in the past. Such simple assessments show good correlations with mortality when assessed over a sizable study population, but have too much variability to be useful for the assessment of one individual.

Why does this matter? It matters because we are now entering the era of rejuvenation therapies, and there are a range of candidate treatments under development. Sooner is better when it comes to assessing the quality of various potential therapies, so as to discard less productive paths in favor of more productive paths. Unfortunately the only truly reliable test at the moment is to wait and see what happens following treatment, for as long as it takes to measure the resulting gains in life span. This requires years in mouse studies, and is clearly impractical in human trials. What if there was a simple, reliable test that researchers generally agree accurately reflects physical age, however? Then scientists could apply the test shortly before and shortly after a treatment, quickly obtain a result, and research and development would proceed much more rapidly.

A range of candidate biomarkers of aging are at various stages of development. Out in front are the DNA methlyation metrics, assessing characteristic changes in epigenetic markers that occur with age. A number of groups are taking a more algorithmic approach instead, attempting to find combinations of simple measures such as grip strength that when processed together can produce a more accurate result. There has also been some experimentation in visual identification of age in humans, proceeding alongside the increased interest in facial recognition technologies that characterizes this unpleasantly surveillance-fixated era of ours. It is plausible that this line of work might achieve the accuracy of other items in the present crop of biomarkers, say a margin of error of 5-10 years of biological age, given sufficient interest and investment. If you go digging through the literature, there is supporting evidence to suggest that facial appearance is, on balance, a decent reflection of age.

So if you can do this for humans, why not for mice? The potential payoff here, if it can be made to work, is the ability to skip over all of the equipment and work needed for physical biomarkers in favor of a hands-off camera and computer system. This might be the case for most of the biomarker assessment needed in exploratory studies in mice as they are currently carried out. Thus this is a potential road to greater automation and lower cost in studies of candidate rejuvenation therapies, though how that cost profile works out in practice is of course very dependent on the details. It is certainly the case the proving out the system, finding whether or not it can be made practical, is a comparatively cheap endeavor. The developers have experience with human facial assessment, computational power is cheap, and visual machine learning is a maturing field of software development. This seems worth a try to me.

AI-powered application MouseAGE will use photos of lab animals to identify new therapeutics to treat aging and age-related diseases is launching a crowdfunding campaign to support MouseAGE, an application to assess visual biomarkers of aging in laboratory animals. This Artificial Intelligence-powered research tool, which is being developed by Youth Laboratories, will help scientists accurately determine the biological age of mice during experiments using advanced visual recognition and machine learning techniques. The project will help speed up research on rejuvenation therapeutics while collecting useful data in a more humane way.

When we are looking at other people, we can easily determine their ages and even get a rough idea of their health by looking at their skin tone, pigmentation and elasticity, their hair color, and their other characteristics. However, the human eye cannot accurately determine subtle changes in the appearance of such tiny animals as mice, and this is where MouseAGE can help. To rapidly collect data, commercial mouse breeders, research labs, and application beta testers all over the world will take and upload many mouse photos to the database. By using machine learning combined with visual recognition, MouseAGE will learn to recognize mice from images, to define their body parts, and finally to detect the subtle visual biomarkers of aging.

If successfully funded, the MouseAGE image collection tool will be available as a free mobile application by mid-October 2017. This will allow breeding houses and research institutions to begin collecting images and send them to the database. The project team hopes to collect enough data by February 2018 and will implement the algorithm for mouse age prediction by April 2018. This biomarker system will be made available as a free application shortly afterwards.

MouseAge: Photographic Aging Clock in Mice

Here at MouseAGE we are aiming to create an artificial intelligence-powered research tool to help scientists accurately determine the biological age of mice and test longevity interventions based on photographic images of mice. This will introduce the first visual biomarker for aging in mice, and will help validate potential anti-aging interventions, save animal lives, and greatly speed up the pace of longevity research. By using machine learning combined with visual recognition, MouseAGE will learn to recognize mice from images, to define their body parts, and finally to detect the subtle visual biomarkers of aging.

We have chosen to start with the C57BL/6 (the black 6) mouse strain. This is the most common lab mouse globally, so it makes sense to begin here. Collected images at this stage will total approximately 10,000, including a wide age range of the black 6 mouse - this estimate based on our earlier experience with human faces. Once we have enough photographic material, artificial intelligence training will begin.

Our primary goal is to develop the MouseAGE system so that researchers can benefit from it. This will be an application that can be installed on a personal smartphone to make, annotate, and upload images to our cloud-based system for analysis, as well as be able to perform age assessment on newly taken images. The cost includes this data collection tool for researchers, mouse recognition software and the creation of an accurate, deep-learned, mouse age assessment algorithm. This will utilize feature extraction techniques to identify visual biomarkers of mouse aging, which we want to have thoroughly tested and made available for widespread use in common lab practice.

There will be Many Marginal Senolytic Drug Candidates

Senolytic compounds are those that can destroy senescent cells with minimal harm to other cells. Since a slow accumulation of senescent cells is one of the causes of aging, effective senolytics will be a form of rejuvenation therapy - and a high-class one at that, since senolytics have the potential to be both cheap and needed only once every few years at most. Now that research aimed at discovery of senolytic drug candidates is underway in earnest, we should expect that one of the outcomes will be a large number of compounds that are in fact not so great at this job: small effects, not discriminating enough in effects on senescent versus normal cells, or otherwise unsuitable. A good sign that the effect size in humans will likely be small is that the compound is already in widespread use, as is the case for most extracts from well-studied plants. I think this one is likely to be an example of the type, along with flavenoids such as fisetin and quercetin.

Intrinsic skin aging is a complex biological phenomenon mainly caused by intracellular stressors. Among various factors that accelerate intrinsic aging, the major causes are cellular senescence and mitochondrial dysfunction. When proliferating cells are exposed to various types of stressors, they may undergo growth arrest, termed as cellular senescence. Senescent cells exhibit various phenomena, such as cell-cycle arrest, gene expression changes, and secretion of inflammatory cytokines. Reactive oxygen species (ROS) mainly accelerate cellular senescence and also play a role in determining the lifespan of mammalian cells. Although senescent cells are relatively rare in young organisms, their number increases with aging. Senescent cells secrete numerous factors that have harmful effects on cells.

Kaempferia parviflora Wall. ex Baker, commonly called black ginger, has been used as a dietary supplement and traditional medicine in tropical countries. K. parviflora is reported to have antioxidative, anti-inflammatory, antiviral, and anticancer activities. However, its effect on intrinsic skin aging has not been verified. We investigated the inhibitory effect of K. parviflora on intrinsic skin aging process by evaluating its effect on cellular senescence and mitochondrial dysfunction using H2O2-exposed human dermal fibroblasts. In addition, its effect on skin aging phenotypes was evaluated using hairless mice.

Based on our results, KPE was found to attenuate cellular senescence in H2O2-treated fibroblasts and hairless mice by suppressing SA-β-gal activity and the expression of cell-cycle inhibitors. The restrained expression of cell-cycle inhibitors upon KPE treatment activates the E2F group, which is responsible for cell proliferation. In addition, KPE prevents cellular senescence by regulating the PI3K/AKT signaling pathway. In conclusion, KPE delays intrinsic skin aging process by inhibiting cellular senescence and mitochondrial dysfunction. KPE does not only attenuate cellular senescence through inhibition of the p53/p21, p16/pRb, and PI3K/AKT signaling pathways but also improve mitochondrial biogenesis through PGC-1α stimulation. Consequently, KPE prevents wrinkle formation, skin atrophy, and loss of elasticity by increasing collagen and elastic fibers in hairless mice.


PCSK9 Inhibition May Reduce Cardiovascular Disease Risk via Immune Mechanisms as well as via Lowered Cholesterol

A range of new approaches to lowered cholesterol aim to improve upon statins in reducing the incidence of cardiovascular disease. One of the most promising of these involves inhibition of PCSK9. How does lowered cholesterol help? Oxidized cholesterol in the bloodstream rises with age as a result of increased oxidative stress throughout the body, and these damaged molecules can irritate blood vessel walls. Cells react by generating inflammatory signals, calling in immune cells to help remove the cholesterol. Unfortunately, these cells may be overwhelmed by the damaged cholesterol. This gives rise to areas of damage that grow to become fatty atherosclerotic lesions, weakening and distorting blood vessels, and ultimately causing death or serious injury when they rupture. When there is less cholesterol, the progression of this condition is slowed. Does PCSK9 inhibition in fact produce all of its benefits through lowered cholesterol, however? The results here suggest that it also interferes with the inflammatory aspect of atherosclerosis.

T cells and dendritic cells are common in atherosclerotic plaques. Atherosclerosis is a chronic inflammatory process in which activation of these immune cells may play a major role in the development of cardiovascular disease. Researchers developed an experimental system to directly study how these immune cells from human atherosclerotic plaques are activated in order to discover mechanisms and potential therapies. Specifically, they examined proprotein convertase subtilisin kexin 9 (PCSK9), which is known to target the low-density lipoprotein (LDL) cholesterol receptor for degradation, resulting in increased LDL levels. Knowledge of this mechanism has led to the development of PCSK9 inhibitors, which lower LDL cholesterol.

Researchers investigated the immune effects of PCSK9 on the induction of dendritic cell maturation and T cell activation by oxidised LDL. T cells were isolated from patients with atherosclerotic plaques and from healthy individuals. Human peripheral blood monocytes were differentiated into dendritic cells. The dendritic cells were pretreated with oxidised LDL and then co-cultured with T cells from atherosclerotic plaques and from blood. The researchers found that oxidised LDL promoted the maturation of dendritic cells. These dendritic cells then mediated the activation of T cells into T helper cells. Oxidised LDL also induced PCSK9. PCSK9 inhibition reversed the effects of oxidised LDL on dendritic cells and T cells. Dendritic cell maturation was repressed, as was the activation of T cells.

"We demonstrated for the first time that PCSK9 inhibition reversed the effects of oxidised LDL on immune activation. This changed a pro-inflammatory profile into an anti-inflammatory state that is potentially anti-atherosclerotic. Our study suggests that the benefits of PCSK9 inhibition extend beyond lowering LDL cholesterol."


Success in Rejuvenation Research to Date is Partial: Many Projects Still Need Our Philanthropic Support to Flourish

The past few years have seen very encouraging progress in rejuvenation research and the commercial development of therapies. Senolytic treatments capable of clearing senescent cells, one of the root causes of aging, are moving towards human trials, with a number of companies hard at work on therapies at various stages of development. The animal data continues to roll in, and continues to look very promising, with senescent cells shown to contribute directly to an increasing number of age-related conditions. In addition the established mainstream efforts to remove age-related protein aggregates such as amyloid-β, tau, and α-synuclein are broadening the number of targets and strategies, and in addition are coming closer to success after many years of failed trials. Amyloid-β has finally been cleared from human brains in a clinical trial, and many of the newer approaches to reducing levels of various forms of aggregate seem quite promising in animal and human studies. These aggregates are another of the causes of aging and age-related disease, there is a real sense that the present time is a tipping point in this area of medical development.

As you've no doubt noticed, this zeitgeist has been reflected here at Fight Aging! in an increased consideration of startup companies and the early steps in translation of the most important lines of research from laboratory to clinic. Similarly, groups like the SENS Research Foundation and Methuselah Foundation have also focused a sizable fraction of their attention on this part of the development process. See, for example, the Rejuvenation Biotechnology conference series of the past few years that brought together academia and industry, and the Methuselah Fund launched this year.

Yet it is important to remember that all of this welcome progress, the move from non-profit research to for-profit development, with human trials on the near horizon, is only taking place for a fraction of the areas of science and technology required for comprehensive human rejuvenation. Yes, senescent cell clearance is well under way now, and both protein aggregate clearance and cell therapies seem well funded and pointed in roughly the right direction. But what about therapies to address glucosepane cross-links, a cause of blood vessel stiffening and bone fragility; or the mitochondrial DNA damage and consequent mitochondrial malfunctions that are implicated in such a wide range of age-related disease; or the scores of other forms of metabolic waste found in lipofuscin and amyloids? What about the decline and disarray of the immune system; what about steering the cancer research community towards universal therapies based on prevention of telomere lengthening, applicable to all cancers?

Aging has multiple root causes. Fixing one root cause - say if senescent cell clearance progresses stupendously well, and we're all having 75% of our senescent cells removed at a $15,000 price tag for a form of FOXO4-p53 interdiction via medical tourism sometime around 2021 - has a limited upside because it is only one root cause. Each of the categories of damage outlined in the SENS view of aging is ultimately fatal in and of itself, though it is far from clear which are more or less important to any specific aspect of aging. Remove just one and some forms of mortality will decrease considerably. Others might be postponed. Yet more might be only slightly affected, however, and they will still kill you. The upside of partial rejuvenation is nonetheless a much better prospect than anything that can be done with yesterday's medical technology, but it is only the opening chapter, not the whole story.

Yes, we should do what we can to help commercial development: invest if we are able, cheerlead and publicize if we can. But we can't become distracted from the important lines of research still underway in their earlier phases, prior to the point at which they can make the leap to startup companies, and in need of philanthropic support to move ahead. Despite the considerable evidence supporting the SENS view of aging as damage and rejuvenation as damage repair, the research community and institutional funding sources continue to give little attention to lines of work that are capable of becoming just as large and just as important as senolytic treatments to remove senescent cells. Prior to 2011, senescent cell clearance was another of those ignored lines of work: that success can and must be repeated for the others.

Of the less well supported lines of work that could turn back aging, those closest to realization appear to be: immune system restoration via some form of targeted cell killing; immune system restoration via regeneration of the thymus; pharmaceutical clearance of glucosepane cross-links; and allotopic expression of mitochondrial genes. These are all still at the stage wherein the charitable donations that we as a community can raise for specific projects, or provide to the SENS Research Foundation, make a real difference. These projects all appear to me to be a few years from reaching viability for commercial development, on average, and they all scrabble for needed funding to one degree or another. All of these should produce similar overall degrees of benefit to those produced by senolytic therapies, albeit in very different ways. This is where we can accelerate progress towards the near future of greater human longevity, just as we have in the past.

Growing success in portions of the broader field of rejuvenation research should encourage us: it shows that the support we have provided over the last decade or more has worked. Things are moving, the wheel turns. We can do the same for the parts of the field that have yet to attract the attention they need, have yet to reach the same level of enthusiasm and funding. Give it some thought.

More Evidence to Reinforce "Use It or Lose It," Even in Later Life

Most older people exercise the body and mind far less than they should; as a consequence some degree of the frailty observed in old age in wealthier parts of the world is preventable, a case of neglect rather than unavoidable outcome. You can't choose not to age, yet, but you can choose to exert yourself in order to make matters better than they would otherwise be. There are plenty of studies to show that, even in very late life, greater levels of mental and physical activity produce benefits. In this paper, the researchers dig deeper to see if certain forms of activity can be tied to specific benefits in cognitive function and physiology, but given the current poor state of health maintenance in the general population, I think it more important as yet another set of evidence to show that "use it or lose it" is very real.

The human hippocampus (HC) is affected not only by pathological aging such as in Alzheimer's disease but also by the normal aging process resulting in deficits in memory, learning, and spatial navigation at old age. Magnetic resonance-studies indicate an atrophy rate of the hippocampus and the nearby parahippocampal gyrus of 2-3% per decade, which is further accelerated in the very old age where there is an annual loss of 1% over the age of 70. On the other hand more recent research has shown that the HC counts among the few brain regions with the ability to generate new neurons throughout the lifespan.

In animal models physical activity has been identified as a key mechanism that can drive this adult neuroplasticity. In humans, research has focused on the effects of aerobic fitness and training on volumes and perfusion of the HC. Results reveal that higher cardiorespiratory fitness levels (VO2 max) are associated with larger hippocampal volumes in late adulthood, and that larger hippocampal volumes may, in turn, contribute to better memory function. Furthermore, some investigations also assessed possible physiological mediators of the observed neuroplasticity, such as brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF). However, the role of cardio-respiratory fitness in modulating hippocampal gray matter volume is still under debate.

The hippocampus is also involved in spatial navigation and in motor sequence consolidation suggesting that motor skill learning and motor fitness can have impact on hippocampal volume without any cardio-respiratory change. Hence, the HC seems not only crucial for long-term memory consolidation, learning and spatial navigation, but also for balancing. Intact balance is essential for social mobility and quality of life in aging. Hence, physical intervention programs should take this function into account, too.

In this respect dancing seems to be a promising intervention since it requires the integration of sensory information from multiple channels (auditory, vestibular, visual, somatosensory) and the fine-grained motor control of the whole body. Behavioral studies have already provided evidence of better performance in balance and memory tasks in elderly dancers, but the underlying neural mechanisms have not been addressed comprehensively so far. Knowing that aerobic, sensorimotor and cognitive training contribute to hippocampal volume, which also seems to be associated with balancing capabilities, we initialized a prospective, randomized longitudinal trial over a period of 18 months in healthy seniors. Two interventions were compared: a specially designed dance program, during which subjects constantly had to learn new choreographies, and a traditional fitness program with mainly repetitive exercises.

Before and after intervention, balance was evaluated using the Sensory Organization Test and HC volumes were derived from magnetic resonance images. Fourteen members of the dance (67.21 ± 3.78 years, seven females), and 12 members of the fitness group (68.67 ± 2.57 years, five females) completed the whole study. Both groups revealed hippocampal volume increases mainly in the left HC (CA1, CA2, subiculum). The dancers showed additional increases in the left dentate gyrus and the right subiculum. Moreover, only the dancers achieved a significant increase in the balance composite score. Hence, dancing constitutes a promising candidate in counteracting the age-related decline in physical and mental abilities.


A Popular Science Article on Calorie Restriction Mimetic Development

This popular science piece covers some of the major themes of recent years in the development of calorie restriction mimetic drugs, pharmaceuticals intended to recreate at least a little of the beneficial metabolic response to lowered calorie intake. The article is a cut above the average in terms of quality, but I remain bothered that this line of work receives so much attention in comparison to far better approaches to the treatment of aging, such as the SENS portfolio of therapies based on repair of the molecular damage that causes aging.

Calorie restriction mimetics cannot produce rejuvenation, and cannot do more than slightly slow aging. They are enormously challenging and expensive to develop, as illustrated by the past fifteen years of investment and failure: there is still no viable, reliable, useful choice if you want to take a calorie restriction mimetic drug, and there is still no full accounting of the cellular biochemistry of the calorie restriction response. The drug candidates on the table such as metformin, mTOR inhibitors, and autophagy enhancers are all some combination of only marginally effective, possessed of unreliable data from animal studies, or producing undesirable side-effects. None come close to the reliability and benefits of calorie restriction itself, but even that buys little in humans, considered in context of the bigger picture of what is possible via the SENS approach of damage repair. People taking a hypothetical perfect calorie restriction mimetic would still age and die on much the same schedule as their untreated peers, gaining only modest benefits. We can do better than this.

Soon to be 50, the respected head of an Australian medical institute is contemplating the latest offering from the anti-ageing industry. It's a product that tops up the levels of nicotinamide adenine dinucleotide (NAD+), a commonplace chemical made by our bodies that is crucial for our metabolism. He's not alone. Leonard Guarente has been taking NAD+ boosters for years; and in 2015 started a company, Elysium, to market them. There are likely thousands of users by now. Something has changed in the anti-ageing field. Eccentrics and gullible-types have always availed themselves of anti-ageing remedies. Dubious supplements feed a mushrooming $30 billion industry. But when evidence-clamouring scientists start popping a pill, you sit up and take notice. Like the soon-to-be-50 Australian professor, most aren't aiming to extend their lifespan; they are aiming to extend their "health span" - the period of time before the diseases of ageing catch up with them.

The rough rule of thumb in nematode worms is: restrict calorie intake by 30% and see up to a 30% increase in lifespan. The effects are smaller in mice and even smaller in primates. Not many people have the willpower to adhere to a lifelong diet, though occasional "fasting mimicking diets" seem to have beneficial effects. Nevertheless the holy grail has been to find a drug that could mimic fasting. Calorie restriction flips a metabolic switch from "abundance" to "austerity". Like when you get a big salary cut, you don't go adding extensions to the house; you hunker down, live modestly, recycle your old things and delay your plans to have babies. Somehow responding to this stress also lengthens lifespan. These days researchers think autophagy plays a big part in the lengthening. For instance, recent studies on mice and humans shows that fasting accelerates the refurbishing of tissues, clearing away damaged "senescent cells" while turning on renewing stem cells.

You might think with all the epiphanies of the past 30 years, surely we know enough about ageing to go full speed ahead with interventions? All the candidate compounds, so far, seem to hack into the same pathway triggered by calorie restriction. Well, yes - but this rabbit hole goes very deep. Over the years, one compelling theory has been that it controls the integrity of mitochondria, the engines of our cells which clearly degenerate as we age. According to the theory, the corrosive by-products of cellular combustion - free radicals - cause ongoing damage as an inevitable consequence of being alive. But numerous recent experiments show that slowing the generation of free radicals in mice or flies doesn't actually slow the ageing process. In fact, it seems to have the opposite effect. Nowadays the paradigm shift is that stress signals like those from free radicals, fasting, or exercise trigger an adaptive anti-ageing response. It doesn't mean past theories are entirely wrong. It's just that there is a lot of other stuff going on in ageing as well.

None of this means the era of anti-ageing medicine has to wait for us to explore every blind alley of the rabbit hole. Indeed, most of the researchers I spoke with passionately believe they are more than ready to start testing the plethora of promising new compounds in their pipelines. What's needed is the faucet at the end - the regulatory framework that will incorporate "ageing" as a medical indication.


The 2017 Summer Scholars Working at the SENS Research Foundation

Each year, the SENS Research Foundation accepts a group of young life science academics and puts them to work on projects in aging research, both at the foundation and in allied laboratories, creating ties between research groups that can help to advance the state of the art. This year's batch has worked on a diverse set of projects that spread out beyond core SENS initiatives such as allotopic expression of mitochondrial genes. Reading through their projects is a reminder that a great deal can be accomplished these days given a small team, a little funding, and an equipped laboratory. Progress in medical research is no longer restricted to very large and very well funded groups: with a postgraduate, a few tens of thousands of dollars, and a few months, it is in fact possible to meaningfully contribute to the field. There is so very much still to accomplish when it comes to bringing methods of rejuvenation to the clinic, but a large fraction of these line items can in fact be helped towards realization by such modest, individual efforts. Early stage research, building the proof of concept and the prototype, has fallen in cost dramatically. The tools of the trade are far cheaper and far more capable than even a decade ago, and knowledge of cellular biochemistry has expanded just as dramatically. This trend will continue.

Just as important as getting things done is to expand the population of researchers who view aging as a medical condition, and who are sympathetic to the model of aging as damage accumulation, and thus also to the goal of therapies based on repair of that damage. The defeat of aging, the construction of a comprehensive package of rejuvenation therapies, is a long term project. The research teams putting the finishing touches to the last of the first generation repair therapies, perhaps twenty years from now, will be led by people who are still in college today. The concept of aging as a reversible medical condition can only be made normal and desirable in the eyes of a world that has rejected this idea by involving ever more people in the research community, among patient advocates, in the population at large. This is as much a matter of education of the next generation as it is of persuasion of the current generation. When considering the scale of the medical industry needed to provide effective means of rejuvenation, given that every adult over the age of 40 will be a repeat customer, it is clear that the whole of the field today, for all its growth, is still just in the earliest stages of bootstrapping. This is the most appropriate time to be building foundations for the long-term.

2017 SRF Summer Scholar Profile: Amelia Anderson

Here at the SENS Research Foundation, I have been working with derivatives of drugs which have been shown to solubilize cholesterol and/or harmful derivatives of cholesterol such as oxysterols. Cholesterol and its harmful derivatives are taken up by cells as they attempt to process these molecules for the body. As macrophage lysosomes become more and more saturated with debris from cholesterol molecules, the cells become useless and form foam cells when they can no longer process the excess cholesterol. These malfunctioning foam cells accumulate in the arterial walls, becoming part of the problem instead of the solution and contributing to the plaques which cause atherosclerosis, or hardening of the arteries. In order to develop a safer, more effective treatment for atherosclerosis, a rational drug design venture is underway at SENS. Various tests have been and will be conducted with novel drugs for the purpose of removing cholesterol and its derivatives from atherosclerotic plaques. For my project, experiments have been designed to assess the effectiveness and safety of these drugs for the purpose of reducing atherosclerotic plaques in human arteries.

2017 SRF Summer Scholar Profile: Sumedh Sontakke

Historically, the pharmaceutical industry's mode of operation is to rely on blockbuster drugs by conducting expensive clinical trials followed by marketing in developed economies if the trials are successful. Unfortunately, this tactic isn't working very well. My research project will attempt to use machine learning methods to improve this dismal statistic. How? Machine learning is a tool that helps us understand how several quantities are related to one another purely on the basis of the data provided. It challenges preconceived notions about factors that influence an output. And, in the field of drug development, this is what is needed given the abysmal attrition rate and burgeoning costs. The algorithms that I will employ will highlight the factors that influence the probability that a drug will clear clinical trials. I plan on predicting the launch or failure of new molecular entities using a model that takes a holistic approach with regards to which variables affect drug success.

2017 SRF Summer Scholar Profile: Alefia Kothambawala

Growing up, I hardly thought of aging as a disease as opposed to a natural result of life. However, as I focused on muscle atrophy during a summer internship, I soon saw the larger scope of the problem. After this experience, I sought to better understand tissue growth, wanting to branch out beyond atrophy. Though Alzheimer's Disease (AD) is a dementia characterized by deficits in memory, spatial skills, and language, over half of AD patients also display psychotic symptoms. The shared psychiatric symptoms between schizophrenia and AD suggest common molecular pathophysiology. Furthermore, previous research has shown that the two diseases bear similarities in neural pathology and biochemical dysfunction. Thus, it would be of interest to study the novel use of antipsychotics, particularly clozapine, to investigate AD psychosis. As a SRF Summer Scholar, I will be working to explore the relationship between AD, clozapine, and CRMP2.

2017 SRF Summer Scholar Profile: Tianhan Deng

Prior to joining the SRF Summer Scholars Program, I was heavily involved in a research project aimed at understanding the biology of low-grade gliomas. My project this summer aims to create the best model for lung-to-brain cancer metastasis. Secondary brain metastases are a devastating condition, bearing a dismal prognosis. A large number of brain metastases originate from lung carcinomas, specifically non-small cell lung adenocarcinomas. Due to its complicated biology and tendency to metastasize, it remains one of the deadliest tumors in the field and has posed a great challenge in finding a cure. A promising step toward finding a cure has been the discovery of TRAIL (Tumor Necrosis Factor-Related Apoptosis Inducing Ligand). TRAIL produce anti-tumor effects by causing tumor cells to essentially "suicide," and its specificity for tumor cells but not healthy cells makes it a great therapeutic approach. My project will focus on selecting a good model to recapitulate the biology of metastatic lung adenocarcinoma and gather the preclinical data for a modified TRAIL as a therapy.

2017 SRF Summer Scholar Profile: Shil Patel

This summer, I will explore stem cell treatment for Parkinson's disease (PD). I will be assessing the genotypes of induced pluripotent stem cell (iPSC) lines from 10 patients with PD to evaluate their genomic integrity. Single nucleotide polymorphisms (SNPs) are common sites of genetic variation between humans. By determining the precise nucleotide at common sites of variation, we begin to get a picture of the genome, and the more SNP sites we examine, the more the resolution of the genomic picture increases. I will load patient skin cell and iPSC DNA onto a microarray chip that can detect the nucleotide identity at 4.3 million SNPs across the genome and use bioinformatics software to identify variations. The results will indicate which of the stem cell lines from each patient are safe to use for transplanting neurons. Using SNP microarrays to assess genomic integrity represents a high throughput quality control testing that can be used to safely create functional neurons from the cells of patients that require no immunosuppression after transplantation.

2017 SRF Summer Scholar Profile: Jasmine Zhao

This summer, my project is to design and test different constructs that can potentially improve the allotopic expression of ATP6 to mitochondria in mutant cell lines. Mitochondria are double-membrane bound organelles that provide energy in the form of ATP to power the biochemical reactions of a cell. Unlike other organelles, however, mitochondria have their own DNA separate from the nucleus, and 13 out of those 37 genes encode for oxidative phosphorylation complex proteins. Due to possible leakage of the high-energy electrons of the respiratory chain, which results in the formation of reactive oxygen species, the oxidative stress mitochondrial-DNA (mtDNA) is subjected to can lead to mutations, aging, and cell death. For instance, the mutations of ATP6 have been implicated in different human diseases that affect neural development, vision, and motor movement.

Allotopic expression has been proposed as a gene therapy approach that can potentially treat mitochondrial-DNA diseases. This method aims to express a wild-type copy of an affected mitochondrial gene in the nucleus of a cell, target it to the mitochondria, and allow functional replacement of the defective protein. Stable allotopic co-expression of ATP8 and ATP6 is able to rescue a cell line that is null for the ATP8 protein and has significantly lowered ATP6 protein levels. However, improving the exogenous amount of ATP6 that can be expressed or targeted to the mitochondria may be necessary in order to achieve complete restoration. Therefore, my project will investigate whether appending an additional gene sequence, the soluble tag, can help stabilize ATP6 and prevent unfolding before it is inserted into mitochondria.

2017 SRF Summer Scholar Profile: Srinidhi Venkatesan Kalavai

Through the SRF Summer Scholars Program, I will be studying the TOR pathway in intestinal stem cells of fruit flies to understand the effect of metabolism on stem cell function. The TOR pathway is involved in cell growth by regulating protein synthesis and metabolism, autophagy, transcription and ribosome biogenesis. The TOR pathway seems to be critical for both the proliferation and differentiation of stem cells and is regulated by many different mechanisms. It has been shown that nutrients can regulate TOR, but the exact molecular mechanism involved in regulating TOR is unknown. Thus, the goal of this project is to better understand the molecular mechanisms that are responsible for TOR activation in intestinal stem cells in response to injury.

2017 SRF Summer Scholar Profile: Anja Schempf

Autophagy is the process by which cells degrade old and damaged organelles and proteins, allowing the cells to prevent damage inflicted by these impaired components. In humans, autophagy helps to prevent the aging of cells, but levels of autophagy tend to diminish as we age. When autophagy levels are lower, muscle disorders and heart issues can occur. My goal this summer is to discover the effect of spermidine, a natural polyamine which has been shown to increase mouse lifespan, on liver tissue and to understand whether spermidine acts in the same way as another autophagy-inducing chemical, rapamycin. The main two protein complexes I will be focusing on are mTORC1 (mechanistic target of rapamycin) and mTORC2, which are protein complexes that regulate autophagy and cell regulation as well as cell metabolism. While the drug rapamycin has been shown to reduce autophagy by lowering levels of mTORC1 and therefore elevating autophagy, it is unclear if spermidine acts through the same pathway, despite producing the same effect. By testing mTOR levels, I will be able to discover whether spermidine acts using the same pathway as rapamycin.

2017 SRF Summer Scholar Profile: Michaela Copp

This summer, I will be working with the SRF Mitochondrial Team. Mitochondria generate the cellular energy consumed by mammalian cells through the process of oxidative phosphorylation. Like the nucleus, mitochondria possess their own DNA, termed mtDNA, which encode for 13 proteins critical to cellular respiration. Unfortunately, mitochondria do not have an efficient system for repairing damaged DNA, leading to mutation rates 10 times greater than that detected in nuclear DNA. Scientists believe evolutionary forces have driven mitochondrial genes from the mitochondria into the nucleus, where they are protected from the highly-reactive oxygen molecules produced by oxidative phosphorylation. The SRF Mitochondrial team hopes to mimic this evolutionary process by providing cells with a modified "backup" copy of the remaining mitochondrial genes at a safe harbor within the nucleus. The procedure of expressing genes in the nucleus originating from the mitochondria is called allotopic expression. Prior to this project, allotopic expression studies on mitochondrial genes had been performed via traditional transfection / virus induction procedures which integrate the new DNA randomly into the host genome. The goal of this study is to express the mitochondrial genes from an identified safe-harbor site in the nucleus in order to minimally disrupt the host genome and ensure the gene functions predictably.

2017 SRF Summer Scholar Profile: Heather Tolcher

I am concentrating my efforts on determining the regenerative process of the heart, focusing on the epicardium. Certain animal species, such as zebrafish, can fully repair cardiac tissue that is lost by injury. In adult zebrafish, activation of the epicardium is observed during the immediate response to tissue damage. This summer, I will be investigating the regulatory sequences that are differentially accessible in the regenerating adult epicardium based on ATAC-seq data. This ATAC-seq data shows which chromatin regions on a specific gene are open and accessible and which regions may possibly act as regenerative enhancers on the epicardium. By selecting certain open chromatin regions at different stages of the regenerative process and by performing perturbation experiments in zebrafish, we aim to further elucidate epicardial contributions during cardiac regeneration. By more thoroughly understanding the molecular events that drive cardiac regeneration, we may be able to provide a new perspective and mechanism for clinical intervention after myocardial infarction.

2017 SRF Summer Scholar Profile: Aashka Patel

My project this summer will explore neuronal circuit connectivity of hiPSCs (cells reprogrammed to become embryonic-like stem cells that can differentiate into various cell types) derived from Alzheimer's Disease (AD) neurons. We are going to investigate how Alzheimer's disease affects neural circuitry and the complexity of communication between affected neurons. Firstly, we will obtain a line of AD stem cells and differentiate them into neurons. AD neurons will be cultured and investigated in a multielectrode array (MEA) plate. This relatively new technology allows measurement of individual neuron depolarization. Using data obtained from MEAs, we can analyze the complexity and duration of communication between neurons. Compared to data collected from an unaffected line of neurons, changes in duration and frequency of bursts (synchronized firing of neurons) can inform us about the complexity of information transferred between neurons.

2017 SRF Summer Scholar Profile: Yujie Ma

My projects will use Drosophila melanogaster, better known as fruit flies, as a model system. In my first project I will investigate the role of a member of the sirtuin family in regulating protein homeostasis (proteostasis) in intestinal stem cells (ISCs). My second project will assess whether altering proteostasis in ISCs influences the proteostasis of cell types found in different tissues. For the cell to remain healthy there must be a fine balance between synthesis/degradation and refolding of misfolded or elimination of damaged proteins. The most common mechanisms a cell can employ to degrade damaged proteins are via proteasome or autophagosome. Unfortunately, aging causes a decline in proteostasis; protein aggregates are more likely to form in certain cells of older organisms. I am interested in understating how adult somatic stem cells (SCs) maintain proteostasis, and I will use Drosophila intestinal SCs (ISCs) as a model system to study proteostasis in adult somatic SCs.

FGF21 Promotes Remyelination in the Central Nervous System

Myelin is the material sheathing nerves, essential to their function. Demyelinating conditions such as multiple sclerosis are unpleasant, disabling, and ultimately fatal, but their effects are an exaggerated version of what takes place in everyone over the course of aging. The myelin sheathing of the nervous system is degraded to some degree in all older individuals, probably a consequence of the general reduction or disruption of tissue maintenance of all sorts that takes place in aging, and this is one of the issues that degrades cognitive function in later life. Researchers here examine the repair processes that respond to loss of myelin, and identify a role for FGF21 in spurring myelin maintenance. Given a way to reliably delivery FGF21 past the blood-brain barrier, this might be a basis for therapy.

Central nervous system (CNS) damage, a hallmark of many CNS disorders, is causatively associated with severe neurological deficits in motor, sensory, cognitive, and other functions. Because damaged CNS can spontaneously regenerate after injury, these neurological deficits partially recover over time. One such regenerative process in the mammalian CNS, remyelination, is initiated by proliferation of oligodendrocyte precursor cells (OPCs), which are distributed widely throughout the mammalian CNS. OPC proliferation and subsequent remyelination processes (e.g., migration, differentiation into mature oligodendrocytes) ensure the restoration of saltatory conduction, provision of trophic support for axons, and promotion of functional recovery; therefore, the mechanism of remyelination has attracted considerable attention in regard to its potential applications in regenerative medicine aimed at treating CNS demyelinating diseases.

Disruption of vascular barriers occurs in several types of disease, including multiple sclerosis, cerebral ischemia, brain tumors, and other neurological diseases. Disrupted vascular barriers can lead to hemorrhage, brain hypoperfusion, and transmigration of inflammatory cells into the CNS; consequently, vascular barrier disruption may exacerbate pathological processes. However, OPC proliferation increases in proximity to demyelinating lesions, which are often characterized by vascular barrier disruption. In addition, some of the cells in the CNS express peripheral-hormone receptors, such as the insulin and mineralocorticoid receptors, which regulate neurogenesis in the adult CNS. Although the role of vascular barrier disruption in CNS regeneration has not yet been clarified, we hypothesized that vascular barrier disruption mediated by CNS injury induces the leakage of circulating factors into the CNS, resulting in remyelination.

In this study, we found that circulating FGF21 promotes OPC proliferation. OPC proliferation was elevated in the spinal cords of mice with toxin-induced demyelination, and this proliferation was inhibited by silencing of FGF21 expression in the pancreas. OPCs expressed β-klotho, an essential coreceptor for FGF21, and inhibition of β-klotho expression in OPCs prevented the increase in OPC proliferation and subsequent remyelination. The results of this study reveal an unexpected role of FGF21, which has been previously characterized as a metabolic regulator. In reviewing previous findings regarding FGF21 function in the CNS, we noted that FGF21 can cross the blood-brain barrier, but the FGF21 level in the cerebrospinal fluid of healthy patients is approximately 40% of that in the plasma. Thus, CNS entry of peripheral FGF21 is limited in normal adult subjects.

We should note that FGF21-mediated OPC proliferation is only one of the mechanisms of remyelination. In terms of molecular mechanism, we just focused on the direct action of FGF21 on OPC proliferation; however, FGF also regulates expression of VEGF receptor 2. Because VEGF signaling is related to brain homeostasis, including OPC migration, a process that involves remyelination, an indirect effect of FGF21 on OPCs may also contribute to oligodendrocyte development and remyelination. Meanwhile, FGF21-associated drugs for treating diabetes have recently been developed by pharmaceutical companies, and some of these compounds have reached the stage of clinical trials. We believe that these FGF21-associated drugs may exert FGF21-mediated remyelination effect and provide clinical benefits in patients with CNS demyelination.


An Immune Response to Viral Infection can Promote Cancer

Here, researchers find an unrelated mechanism by which an immune response to invading viruses might as a side-effect damage DNA in cells, and thus raise the risk of certain types of cancer. Both bacterial and viral infections of various types have been linked to increased cancer risk. There is no doubt a diverse set of mechanisms yet to be discovered that might explain these correlations. You might recall a recent paper suggesting that some bacteria force a more rapid pace of replication in stem cells, boosting the occurrence of mutational damage as a result, for example. That is very different from the mechanism uncovered in this research, and we might expect other mechanisms to be equally varied.

Infection with human papilloma virus (HPV) is the primary cause of cervical cancer and a subset of head and neck cancers worldwide. A new paper describes a fascinating mechanism that links these two conditions - viral infection and cancer. The link, basically, is a family of enzymes called APOBEC3. These APOBEC3 enzymes are an essential piece of the immune system's response to viral infection, attacking viral DNA to cause disabling mutations. Unfortunately, the action of family member APOBEC3A can spill over from its attack against viruses to induce DNA mutations and damage in the host genome as well. In other words, this facet of the immune system designed to scramble viral DNA can scramble human DNA as well, sometimes in ways that cause cancer.

"We know that the majority of cancers are caused by genetic mutations. And we know some of the mechanisms that cause these mutations, for example UV radiation can cause mutations that lead to skin cancer and smoking can cause mutations that lead to lung cancer. But there are many more cancers in which we don't know the source of the mutations. The APOBEC3 family can explain how some of these mutations are created. In fact, APOBEC3A can be activated in many ways - not just with HPV infection - and its action may drive a percentage of oncogenic mutations across many cancer types."

Data from the Cancer Genome Atlas showed signatures of APOBEC3-mediated mutations in the PIK3CA gene of about 40 percent of HPV-positive head and neck cancers, but only about 10 percent of HPV-negative head and neck cancers. Adding to this storyline of APOBEC3A-mediated oncogenesis was the fact that expression of APOBEC3A was much higher in HPV-positive cancers. Interestingly, this system that so heavily risks damaging host DNA doesn't work so well against its intended target - APOBEC3A does not successfully eliminate the HPV virus, which remains as a chronic infection. "We have another paper from 2015 showing that HPV has revised their genome against this APOBEC3 enzyme, altering and reducing the target sequences in their own DNA. If APOBEC3 fails to recognize its target sequence, it does not interrupt the DNA. In this, we can see the complex race of evolution - the host evolves the APOBEC3 system to target viruses, but then the viruses evolve their DNA to evade APOBEC3. We are not at any endpoint of evolution - what we may be seeing is the our body's attempt to use this APOBEC3 system to help it evolve more quickly in response to the virus."


Human Trials of Therapies that Aim to Clear α-synuclein from the Aging Brain

A major theme in rejuvenation biotechnology is periodical removal of metabolic waste. The accumulation of various altered proteins into solid deposits that are not found in young tissues is a form of damage. The presence of this waste at best alters cellular behavior in undesirable ways, and at worst causes harm and cell death. This is a root cause of aging, and thus the ability to safely remove the buildup of waste, once achieved, will be a form of rejuvenation. There are many forms of unwanted waste proteins found in old tissues: the amyloid-β and tau best known for their appearance in Alzheimer's disease; the transthyretin amyloid of senile systemic amyloidosis; the many constituents of lipofusin, including the A2E that contributes to cell death in retinal degeneration; the glucosepane cross-links that make bone become brittle and arteries stiffen; and the topic for today, the α-synuclein implicated in Parkinson's disease and other synucleinopathies.

The research community is slowly making inroads into the development of clearance therapies. The most funding has gone into Alzheimer's and amyloid-β, but there is more interest now in tau and α-synuclein than there was in the past. The SENS Research Foundation has done a great deal to pick up the slack where other forms of waste were being ignored: they funded the work that lead to A2E clearance development at Ichor Therapeutics, for example, have worked on breaking down 7KC, one of the compounds implicated in atherosclerosis, and are currently coordinating a research effort aimed at the production of drug candidates to remove glucosepane cross-links. So far, however, only amyloid clearance can claim a large number of initiatives with significant funding that reached the stage of clinical trials. Still, progress is underway and funding is growing in the matter of α-synuclein, as this essay from the SENS Research Foundation notes.

Human Trials of Two New Rejuvenation Biotechnologies Targeting Alpha-Synuclein

Parkinson's disease (PD) is diagnosed on the basis of what are called "motor symptoms" of the disease. This group of symptoms is caused by the progressive loss of dopamine-generating neurons in an area of the brain called the substantia nigra pars compacta (SNc). But there's another group of PD symptoms, termed the "non-motor symptoms" (NMS) of PD, that gets far less attention, even though NMS begin to manifest earlier in the disease, are harder to treat with current therapies, and include some of the most crippling features of living with the later stages of PD.

Whereas PD motor symptoms are driven by loss of dopamine-producing neurons, many of the nonmotor symptoms are instead linked to the accumulation of Lewy bodies and other malformed clumps and fibrils of the protein alpha-synuclein (AS) inside and between neurons. The various forms of aggregated AS first appear in neurons in the periphery of the body (that is, outside of the brain and spinal cord), and then invade the brain, starting from the base of the skull and slowly spreading their way forward across the brain over the course of the disease.

Because most NMS are not driven primarily by loss of dopamine signaling, dopamine-boosting treatments are completely ineffective in controlling most of them. Yet there's now hope: a race amongst several biotech companies to develop rejuvenation biotechnologies to clear AS aggregates out of the aging and early PD brain. These companies are taking what, in SENS terminology, is the amyloSENS approach, developing and testing antibodies that recognize and bind to malformed AS, allowing them to interdict the toxic proteins as they spread from one neuron to the next, and possibly also capturing some of the aggregates inside existing neurons and facilitating their degradation. By sweeping away AS aggregates before they get a chance to spread, AS immunotherapies have the potential to hold the nonmotor symptoms of PD at bay, slowing the overall progress of the disease, and - when combined with mature cell therapy - eventually preventing the disease altogether, and potentially even reversing it.

When we last reported news from Prothena Corp PLC, the founder had recently presented the results of studies using their AS-targeting antibodies at SENS Research Foundation's Rejuvenation Biotechnology 2014 conference. Scientists at Prothena had confirmed that several of their candidate antibodies were able to clear AS pathology out of the brains and spinal cords of mouse models of PD and related disorders, substantially shielding them against the PD-like motor and cognitive impairments suffered by their untreated cousins. They also revealed some very early information specific to PRX002, the humanized version of the most promising antibody tested in the mouse studies, which was then slated to enter into early-stage human trials.

Now we can report on the first published results of those trials, and on early information coming out of an additional trial that has not yet been formally published. For their first basic safety and pharmacokinetics trial, Prothena scientists recruited 40 healthy people without PD to receive either placebo injections or or one of 5 doses of PRX002, ranging from 1 to 30 mg/kg. An hour after dosing, the lowest dose of the antibody led to a reduction of AS in the circulation of more than 30%, with the highest doses reducing it by up to 96%; 24 hours later, levels remained similarly suppressed in the higher-dose groups.

We learned more about the potential of PRX002 from a sneak peak at the interim results from an ongoing Phase 1b clinical trial of of PRX002 in PD patients. This was a larger (80 subjects) trial that for the first time involved volunteers suffering PD - most with the early stages of the disease. The effects of the first dose of PRX002 on serum AS in PD patients were similar to what was seen in young, healthy people in the first trial: up to a 97% decline in the ratio of free to total AS at the highest dose, with the ratio remaining strongly suppressed for at least four hours. But now for the first time, they could see the longer-term effects of each dose. A month after receiving their first dose, just before taking their second shot, subjects' free-to-bound AS ratios had only partially returned to where they had been before receiving their first dose. No serious adverse reactions to PRX002 were observed in trial participants. There was no improvement in symptoms or other signs of disease progression, but no firm conclusion can be drawn from this due to the short duration of the trial period.

Biotech pioneer Biogen has been rather quiet about their work on their AS-targeting antibody BIIB054 - unlike their widely-heralded Aducanumab, another amyloSENS-style immunotherapy, which has generated enormous excitement for what seems to be the clearest-cut effect on both beta-amyloid and problems with cognitive function in people with Alzheimer's disease. They initiated their Phase 1 BIIB054 trial in 2015, and reported promising early results of its use in an animal model of Parkinson's back in the summer of 2016, but have never published the results, issued press releases, or held conference calls to share their findings with the wider public. But all the while, BIIB054 has been jumping one hurdle after another, and the company is powering ahead.

BIIB054 initially emerged as a strong candidate anti-AS imunotherapy. In further testing, BIIB054 selectively bound aggregated AS in tissue samples from people with PD and with Dementia with Lewy Bodies (DLB - a related disease of AS-driven neurological aging), while leaving native AS alone. The company's scientists also report that when they then injected preformed AS fibrils into the brains of mice, BIIB054 slowed the self-templating spread of AS pathology across the brain, and held much of the ensuing motor dysfunction at bay. Based on these results, Biogen advanced BIIB054 into a Phase 1 clinical trial in 2015. 48 healthy people without PD, aged 40-65, were given a single dose of BIIB054 at one of six doses across a very wide range, and followed up for the next 16 weeks using multiple clinical and laboratory assessments, as well as MRI and electrocardiogram data. The results reported so far are similar to the PRX002 results as far as they go, but are clearly at an earlier stage.

Overall this is an exciting moment. Multiple amyloSENS rejuvenation biotechnologies have now emerged from the rejuvenation biotechnology ecosystem, targeting the removal of aggregated alpha-synuclein from the brain and being tested in early-to-mid-stage human clinical trials. Each uses a different approach to targeting these malformed proteins, and is supported by data in animal models - and the early human evidence looks favorable, if very preliminary. And there are more in the pipeline, including candidate AS immunotherapies from Proclara, NeuroPore, and BioArctic Neuroscience. All this suggests that multiple developments are converging toward groundbreaking progress in this area.

Better Vascular Function Correlates with a Slower Decline of the Brain

Age-related declines in cardiovascular health correlate well with neurodegeneration, particularly vascular dementia. The brain is an energy-intensive organ, and reductions in delivery of nutrients have a definite impact. Beyond that there is also the matter of small-scale damage to tiny blood vessels that occurs as a result of dysfunction in the vascular system: rising blood pressure combined with failing mechanisms in blood vessel walls leads to ruptures that produce tiny areas of damage. A range of other mechanisms are also candidates for linking vascular health with brain health in later life. For here and now, one of the lessons to take away is that better maintenance of fitness and vascular health will likely also postpone cognitive decline in old age. It is further worth considering that any of the near future rejuvenation therapies capable of reversing loss of cardiovascular function will also likely help the brain.

Age-related decreases in vascular health are a common finding in the literature and represent one of many potential mechanisms that contribute to declines in the integrity of the aged brain. Identifying clinical markers of vascular health that serve as surrogate signs of brain health is paramount for early intervention and prevention efforts. Ideal markers of vascular health would be non-invasive, able to detect early changes in vascular function, easily administered in clinical settings, and related to neuroimaging techniques that are sensitive to age-related vascular decline.

Neuroimaging indicators of white matter (WM) health, including fractional anisotropy (FA) and WM hyperintensities (WMHs), are sensitive biomarkers of age-related vascular decline. WMHs are associated with increased pulse-wave velocity, a measure of conduit artery stiffness, and FA is significantly decreased in vascular disease. In addition, changes in FA appear to precede the manifestation of irreversible WM lesions, and are predictive of future cerebrovascular incidents. Despite this evidence, less is known about the relationship between these neuroimaging predictors and early detectors of cardiovascular disease, such as endothelial function.

The vascular endothelium is a single cell layer lining all blood vessels. It plays a critical role in regulating vascular tone by mediating the relationship between luminal blood flow and arterial smooth muscle. When compromised, the endothelium contributes to the pathogenesis of vascular disease. Advancing age is associated with endothelial dysfunction, and endothelial dysfunction is associated with Alzheimer's disease and vascular dementia. Moreover, blood markers of chronic endothelial dysfunction are associated with rarefaction of WM. Collectively, these findings suggest that endothelial function may play a critical role in combating age-related declines in brain health.

Endothelial function can be measured non-invasively through the use of digital pulse amplitude technology, which allows for the assessment of vascular function at the fingertip. This measure of peripheral arterial tone (PAT) is correlated with changes in vascular tone using flow-mediated dilation techniques. Little is known about the relationship between endothelial function and WM health. Endothelial cells mediate vessel caliber, and age-related endothelial dysfunction may induce vasoconstriction and chronic hypoperfusion of WM. Ischemia can then lead to myelin degeneration and selective oligodendrocyte death. Recent findings support this mechanism by demonstrating a relationship between microvessel caliber and normal appearing WM.

The Trail Making Test (TMT) is a reliable and valid assessment of executive function that is related to WM health and overall brain health. In the present study, we used a non-invasive measure of PAT to test the hypothesis that endothelial function is associated with WM health and executive function. We then expanded on these findings by exploring the potential relationships between a measure of executive function, the TMT, and both WM health and reactive hyperemia. Our results demonstrate that a peripheral measure of endothelial function, reactive hyperemia index (RHI), is positively correlated with WM microstructure in the corpus callosum in older adults, but is not related to WMH volume. The results from tractography analyses suggest that portions of the corpus callosum most strongly correlated with WM microstructure were those involved in higher-level cognitive processes. These findings motivate future longitudinal studies aimed to determine if increasing endothelial function, through lifestyle modification, attenuates age-related declines in WM microstructure and executive function.


Piezo1 as an Exercise Sensor

Efforts to create an exercise mimetic drug first require identification the controlling mechanisms of the response to exercise,and researchers here report on one such mechanism. Given the past twenty years of research into calorie restriction as an example, we should not expect great progress to rapidly emerge from any one such identification of a regulatory protein involved in exercise, however. Many mechanisms have been identified for calorie restriction over the years, and yet here we stand without meaningful, reliable, useful calorie restriction mimetic drugs in the clinic. What this does illustrate is that recreating altered states of metabolism as a basis for treatments is both very hard and very expensive, with a poor chance of near-term success. Even as the first interesting target mechanisms for potential exercise mimetics emerge, this part of the field still has a decade or more to go before it reaches the equivalent point to today's calorie restriction mimetic research.

A research team has found that a protein called Piezo1 in the lining of blood vessels is able to detect a change in blood flow during exercise. They have described the protein as an 'exercise sensor'. During physical activity - as the heart pumps more blood around the body - the Piezo1 protein in the endothelium or lining of the arteries taking blood from the heart to the stomach and intestines senses the increased pressure on the wall of the blood vessels. In response, it slightly alters the electrical balance in the endothelium and this results in the blood vessels constricting. In a clever act of plumbing, that narrowing of the blood vessels reduces blood flow to the stomach and intestines, allowing more blood to reach the brain and muscles actively engaged in exercise.

The scientists say this is ground-breaking research because it identifies for the first time a key biomolecular mechanism by which exercise is sensed. They believe the health benefit of exercise maybe linked with the fact that blood flow is being controlled to the intestinal area. "If we can understand how these systems work, then we may be able to develop techniques that can help tackle some of the biggest diseases afflicting modern societies. We know that exercise can protect against heart disease, stroke and many other conditions. This study has identified a physiological system that senses when the mammalian body is exercising."

The researchers also investigated the effect of an experimental compound called Yoda1 on the action of the Piezo1 protein. They found that it mimicked the action of increasing blood flow on the walls of the endothelium which is experienced during physical activity, raising the possibility that a drug could be developed which enhances the health benefits of exercise. "One of our ideas is that Piezo1 has a special role in controlling blood flow to the intestines and this is really an important part of the body when we start to think about something called the metabolic syndrome which is associated with cardiovascular disease and type 2 diabetes. By modifying this protein in the intestines then perhaps we could overcome some of the problems of diabetes and perhaps this Yoda1 compound could target the Piezo1 in the intestinal area to have a functional effect. It may be that by understanding the working of the Yoda1 experimental molecule on the Piezo1 protein, we can move a step closer to having a drug that can help control some major chronic conditions."


Kelsey Moody on Antoxerene and the Near Future of Applied Aging Research

Antoxerene formally launched today, concurrently with a $1.5 million funding round, a spin-off venture of Ichor Therapeutics. I recently had the chance to ask Kelsey Moody at Ichor Therapeutics a few questions on the new lines of work that will proceed under the Antoxerene umbrella, as well as his thoughts on the current state of the industry; I think you'll find those interesting. It looks like involvement in the growing senolytics industry is on the cards, and why not? That market will be enormous, with room for many companies and classes of therapy.

As you'll no doubt recall, the staff at Ichor Therapeutics are working on an implementation of technology developed at the SENS Research Foundation with the intent of removing age-related metabolic waste that contributes to macular degeneration. They have a broad range of aspirations beyond this goal, however. When the technology at the heart of Antoxerene was first pointed out to me, a while back, the core of the thing was a novel approach to protein manufacture, just getting started on the long road of commercial development. Infrastructural improvements of this nature are what drive progress in the long term: they are essential to the process of making the various potential applications of scientific progress cheap enough and reliable enough to be practical. This new technology has since been brought into the fold for uses relevant to the development of therapeutics to treat the causes of aging, and that initiative wrapped into the company now called Antoxerene.

Antoxerene has the look of a sizable expansion of the work at Ichor Therapeutics. Could you give an overview of the initiative?

Antoxerene is a pharmaceutical company that develops small molecule drugs for pathways of aging. Many protein-protein interactions are known to contribute to the onset and progression of age-associated disease. One such example is p53. p53 is a master cell regulator that should force apoptosis in cells that become cancerous or senescent. Cancer is obviously a major disease of aging. Senescent cells are non-dividing pro-inflammatory cells that exacerbate or may even cause many diseases of aging. A common feature of both cancerous cells and senescent cells is the ability to inhibit p53. Many cancers achieve this by overexpressing a protein called MDM2, which binds p53. Similarly in senescent cells, a protein called FOXO4 is overexpressed which binds p53. In both cases, p53 is prevented from performing its function and cells that should be eliminated from the body are allowed to persist. One of our goals is to identify small molecules that can disrupt these interactions and reactivate p53. These leads can then be developed as highly targeted drugs to treat cancers and diseases of cellular senescence.

What is it about the underlying protein production technology that makes now a great time to be undertaking this drug discovery work?

Antoxerene is following a traditional small molecule drug discovery path, but we have advanced the state of the art. The typical workflow for drugging a pathway is to manufacture large quantities of the proteins of interest (for example, p53 and FOXO4), then test a library of compounds to identify "hits" that stop the proteins from binding. However, protein manufacturing is often non-trivial, and large quantities of protein are required for a high throughput screen. Complicated proteins like p53 cannot be made using inexpensive microbial systems like E. coli because these bugs lack essential machinery found in mammalian cells. Expression within mammalian systems is possible, but cannot be scaled cost effectively. Because of this, the state of the art for drug discovery is to use small fragments of the proteins of interest, rather than full-length protein. Of course, this is analogous to evaluating a used car by looking at a hubcap. It may or may not accurately depict the state of the entire car.

Under a co-development deal with Finger Lakes Bio, Antoxerene has used proprietary RecombiPure expression technology to manufacture full-length, properly folded, bioactive proteins at scale in E. coli. While everyone else is looking at hubcaps, we see the entire car.

One of your Antoxerene development projects, BuckyProtector, is an antioxidant. Antioxidants have a decidedly mixed history when it comes to therapeutic application and aging. What is new and different here?

BuckyProtector is a combination moon-shot / community service project. Back in 2012, Baati et al described a profound decrease in all-cause mortality in rats that were fed a fullerene formulation. No group has replicated those findings, but a number of people have begun consuming this product from various online vendors. In our hands, we find tremendous variance in the formulation from vendor to vendor, and none of the vendors we contacted were able to provide quality assurance data that support label claims of contents and purity. Preliminary studies suggest that some of these formulations may be highly toxic. We have brought proper manufacturing and quality control in house and are working to definitively answer whether development of a fullerene therapeutic is worthy of a serious translational effort. We hope to have more to report on this front in the coming months.

I see that FOXO4-p53 is on the list of targeted mechanisms. Is Ichor getting into the senescent cell clearance field in a significant way? What do you think of the prospects for this area of development?

Our interest in the senescent cell clearance field will largely depend on what we find during our initial screens. However, we are open to the idea of having a significant focus in the space. The field is heating up, and we have specific expertise in drugging p53 pathway interactions that make us uniquely suited to take on a discovery initiative around FOXO4-p53. This seems like an area where we can make a large impact in a cost effective and timely manner.

The last few years have seemed very positive from the point of view of progress towards the treatment of aging, in terms of gaining support and building working technology. What are your predictions for the next five to ten years?

This is difficult to predict because it is unclear to me what impact the tech sector will have on the life sciences, and drug development in general. What I have observed over the past 3-5 years is a growing interest among software and tech entrepreneurs and investors in the life sciences, and the aging space in general. Some companies, such as BioAge Labs and Insilico Medicine, are looking to apply modern computational approaches to drug discovery, with a focus on aging. Others, such as Unity Biotechnology or Oisin Biotechnologies, are pursuing more traditional translational research initiatives, but with substantial financial support from tech investors. We even see a number of software and tech entrepreneurs entering the life sciences, such as with Immusoft.

It is uncertain what levels of success these companies will achieve, but I am optimistic. To the best of my understanding these are well thought out initiatives being led by strong teams. However, there is a tendency for some people from the software and tech sectors to think biology is a coding problem that can be solved by throwing money at it, and seem to gravitate towards personalized health, synthetic biology, biohacking, and similar initiatives. This is great for driving interest in aging research or developing a profitable consumer product, but when lofty expectations are met with the harsh reality of bench science, particularly in drug development, there is a high risk that ambitions will be stifled.

The Ellison Medical Foundation was an early example of this. Up to $40 million per year was spent on aging research starting in 1998. With relatively little to show for it, the program was concluded in 2013. It is not sufficient to throw money at research problems, particularly when drug discovery is the goal. And this is a trap high net worth individuals seem to repeatedly fall into. The basic science, medicinal chemistry, toxicology, formulation work, regulatory pathway, clinical trials, IP strategy, and business strategy all rely upon incredibly divergent skill sets. It is rare to find a team that possesses all of them. New investors in particular should be grilling entrepreneurs on the details of these points, not getting caught up in the hype of cool technology (though the latter is certainly the more fun part).

All that said, collectively I believe the future for the treatment of aging is bright. Aging research is becoming a mainstream discipline as the research questions are becoming clearer. "How do we cure aging?" doesn't fly. Better questions lead to better answers. "What level of therapeutic efficacy will be achieved for disease X with a targeted FOXO4-p53 drug that selectively eliminates senescent cells?" We hope to find out.

How can our community help Ichor to succeed in this latest venture?

By writing. Ichor has a great opportunity to begin leveraging NY government programs for funding, tax incentives, and exposure. If pursued properly, these can do an enormous amount to leverage investor funding and promote public interest in aging research. There are not a lot of players in the Syracuse area where we operate, and we are getting noticed. Letters from the community will help. It does not matter where you live. Type or write two copies of a letter made out to Senator John DeFrancisco and Rob Simpson and physically mail it to Senator John DeFrancisco's Syracuse office or Rob Simpson's Syracuse office respectively.

Tell them that you read about the exciting new research Ichor Therapeutics is doing in Syracuse. Tell them that their Grants for Growth program provided essential seed funding for getting both of Ichor's initiatives (Lysoclear and Antoxerene) off the ground, and raise millions of dollars in follow-on funding. Tell them that you are excited to see people in government taking an active role in promoting medical research on age-related disease, particularly start-ups. Tell them that you wish your government would do the same. Tell them that you hope they continue to support companies like Ichor in the Syracuse region. It is important that these letters be "mainstream" friendly. Ichor is not curing aging. We are developing first in class drugs for age-associated disease. It doesn't have to be long or fancy, but in a small city like Syracuse, your letters will be noticed. They will matter. They will drive decisions.

Changes in Microvesicles as a Potential Marker of Cellular Senescence

One of the ways in which cells communicate and react to one another is via vesicles, small membrane-wrapped packets of proteins. Cell signaling in general is an important part of the detrimental effects of senescent cells on tissue function and health, and so changes in signal mechanisms might prove to be a useful marker of the presence of such cells. Now that therapies based on clearance of senescent cells are under active commercial development, there is considerable interest in the scientific community in better ways to identify and classify senescence in tissues. This open access paper is an example of the sort of research presently taking place.

Mesenchymal stem cells (MSCs) have been found to broadly distribute throughout the body and have the potential to differentiate into lineages of mesenchymal tissues such as bone, fat, and cartilage cells. Recently, MSCs have become a promising tool for cell-based therapy in tissue engineering and regenerative medicine. There is considerable evidence that MSC senescence is considered as a contributing factor to aging and aging-related diseases and replicative senescence impairs the regenerative potential of MSCs. To better understand and monitor cell senescence in MSCs, it is necessary to have a reliable biomarker for identification of these cells.

Unique phenotypic alterations of senescent MSCs have been reported including enlarged morphology, arrested proliferative capability, increased β-galactosidase activity, telomere shortening, accumulation of DNA damage, alteration of chromatin organization, reduced expression of surface antigen markers, up-regulation of cell cycle inhibitors (P16INK4A and P21WAF1), and senescence-associated secretory phenotype (SASP). Since surface and external factors can be detected without intracellular delivery of a probe and without harming the cells, they can serve as ideal biomarkers to identify senescent cells. Senescent MSCs release a specific secretome, including matrix metalloproteinases (MMP2, TIMP2), cytokines (IL-6), insulin like growth factors binding proteins (IGFBP4, IGFBP7), and monocyte chemoattractant protein-1 (MCP-1). The role of these factors has been investigated in the identification of MSC senescence.

As a key component of the cell secretome, microvesicles (MVs) are shed from cell surface by their parental cells into the extracellular environment. Recent reports indicate that these small vesicles can mirror the molecular and functional characteristics of their parental cells and participate in important biological processes, such as the surface-membrane trafficking and the horizontal transfer of proteins and RNAs among neighboring cells. A growing body of evidences has shown that MVs shed by MSCs (MSC-MVs) express MSC-related markers, which act as key effectors of MSCs. Many biological functions have been attributed to MSC-MVs, such as tissue repair, hematopoietic support, immunomodulatory regulation, and inhibition of tumor growth. Recently, it has been reported that old rat MSC-MVs have unique miRNAs and significantly inhibited TGF-β1-mediated epithelial-mesenchymal transition; however, no information is available on whether MSC-MVs could represent characteristics of their parental cells in senescence.

In the present study, we investigated the changes in MSC-MVs when their parental MSCs experienced senescence, including MSC-MV size distribution, concentration, surface antigens, osteogenesis-related functions and miRNA content, to characterize these senescent MSC-MVs and evaluate their ability to resemble their parental senescent MSCs. Our findings provide evidence that MSC-MVs are a key factor in the senescence-associated secretory phenotype of MSCs and demonstrate that their integrated characteristics can dynamically reflect the senescence state of MSCs representing a potential biomarker for monitoring MSC senescence.


Starting in on the Identification of Mechanisms by which Gut Bacteria Influence Aging

It is now fairly well established that gut bacteria have a degree of influence on the pace of aging, though just how much of individual variation can be explained in this way is still a question mark. The next step in the process of investigation is to identify the most significant mechanisms involved. This will no doubt proceed in much the same way as investigations of the mechanisms of calorie restriction and exercise, with researchers seeking ways to mimic the presence of favorable gut bacteria populations via pharmaceuticals. Just like those other parts of the field, this probably isn't going to result in therapies that can meaningfully slow aging any time soon, however. It is a challenging area of development, as illustrated by the lack of practical outcomes resulting from the past decade of work on calorie restriction mimetics. Further, the possible effect sizes are too small to care about in comparison to what can be achieved in principle through rejuvenation biotechnologies such as those of the SENS research portfolio.

A class of chemicals made by intestinal bacteria, known as indoles, help worms, flies and mice maintain mobility and resilience for more of their lifespans, scientists have discovered. Healthspan is a term used to describe the length of time a human or animal, while aging, can stay active and resist stress. In this research, the focus is on whether the animals live healthier, but not necessarily longer. "This is a direct avenue to a drug that could make people live better for longer. We need a better understanding of healthspan. With medical advances, people are living longer; but you might not really want to live longer if it means spending those extra years frail and infirm." The burden imposed by diseases of aging on the healthcare system is expected to skyrocket in coming decades.

Interest in the health effects of the microbes that live in our bodies has exploded in recent years. In humans and mice, some studies have shown that the spectra of bacteria in our bodies become narrower with age. Indole, produced by many types of bacteria through breakdown of the amino acid tryptophan, can smell noxious or flowery depending on the concentration. Indole and its chemical relatives can be found in plants, especially vegetables such as broccoli and kale. One such relative is also known as auxin, a growth hormone for plants needed for light-seeking and root development.

The roundworm C. elegans is one of the premier organisms in which to study aging. Studies in C. elegans led to discovery of a set of genes that control how long the worms can live. Several of the genes are components of the insulin signaling pathway, and they influence lifespan in flies and mice as well. Worms normally eat bacteria. So researchers fed them E. coli bacteria that produce indoles, and compared them with worms fed E. coli that cannot produce indoles. As they age, older worms spend less time moving around, can't swallow as well and are more sensitive to stressors. Although indoles didn't change the maximal lifespan, they markedly increased the amount of time worms were mobile after the age of 15 days, and it increased their swallowing strength and resistance to heat stress, even in young animals. In addition, worms usually stop reproduction at the age of 5 days, but dietary indole more than doubled their reproductive span, allowing them to remain fertile up to 12 days.

Indole had similar effects on mobility and resistance to heat in Drosophila fruit flies, and with mice, a comparable pattern was evident. Researchers treated mice with antibiotics to eliminate the existing flora, and then re-colonized them with either normal E. coli, or, as a control, with bacteria that cannot produce indole. In very old mice (28 months), indoles helped animals maintain their weight, mobility and activity levels. In younger mice, indoles extended survival after exposure to lethal radiation. Indoles may be keeping the intestinal barrier intact and/or limiting systemic inflammatory effects. Researchers are now investigating how indoles exert their effects in aging animals, how dysregulation of indoles produced by the microbiota contribute to frailty, and how indoles can be used to reverse these effects.


Venture Funds for Longevity Science: an Interview with Laura Deming

Laura Deming runs the Longevity Fund, which was arguably the first of the current small group of venture funds focused on supporting companies that commercialize implementations of aging research, depending on how we want to classify the incubator activities of the Methuselah Foundation over the past decade. The fund invested in Unity Biotechnology, so I have to imagine it will do fairly well as a result: senolytic therapies such as those under development at Unity Biotechnology are ultimately going to be a bigger market than just about anything else that presently exists in the medical community. Every human much over the age of 40 is a potential customer at some price point.

Much of Deming's work in the venture community these past years has been behind the scenes, with little public advocacy, and I think this a pity as she usually has interesting things to say on the matter. Progress in growing this community, its funding, and its progress, requires more of the people involved to at least once in a while step up and talk in public about the support they are providing to research and development in the field of longevity science. While we can't all be publicity engines like Aubrey de Grey, or Michael West, or the like, I think there are many missed opportunities to do good at little cost by speaking out.

This 23-year-old just closed her second fund - which is focused on aging - with $22 million

TC: What did you study at MIT?

LD: I majored in physics actually, but I continued to work in a couple of labs, including [one overseen by] Lenny Guarente [a biologist known for his research on life span extension]. It was a lot of fun. I thought I'd be a scientist, but a grad student familiar with the Thiel fellowship told me I should apply and I did. It's funny, one of the directors of the [Thiel] program told me recently that he thought I'd fail, even though he was very supportive. After we closed the first fund, he was like, "I never thought that would work out."

TC: Why?

LD: In part because not long ago, if you talked with most VCs about aging, they didn't think there was anything there. I think aging is such a young science, they hadn't heard about it. Meanwhile, I care a lot about it, and though we don't know if it'll work or not, it's not unlike [biotech companies trying to tackle] cancer in that way, and if you believe in cancer companies, you should also care about aging companies.

TC: How much did you raise for that first fund?

LD: A grand total of $4 million, and I was very proud of this. To be honest, I'd assumed $100,000 was enough to build a fund until I arrived in San Francisco and realized it was really enough to live on for two years. When I started fundraising, I was 17 - too young to legally sign contracts. I'd never managed money before. But I could talk to people about the science and got them on board with that. In the end, we had great anchor investors come together, and we invested in five companies that kind of proved out the strategy.

TC: One of your portfolio companies is Unity Biotechnology, a company that's trying to reverse aging through therapeutics. Didn't it just raise a giant Series B round this week?

LD: It did. All of the companies in that portfolio have [at least] raised series A rounds of $30 million or more to get to that proof of concept.

TC: Given the amounts involved, is the plan to form special purpose vehicles, or SPVs, around your break-out winners?

LD: We like to help LPs follow on, so we look to do that in whatever way makes sense for both parties. With Unity, we put in money as early as possible because Ned Davis, who runs the company, is amazing and we thought its aging thesis would succeed.

TC: Do you think your work will be harder, given that investors seem to be paying much more attention to aging suddenly?

LD: No. With our first fund, we spent up to six months with each deal, tracking the company before it was even raising. It's something LPs really value from us; they know when they invest in something that they don't need to re-do the diligence, that we've already looked at a bunch of stuff and we know this is the best possible investment in [a particular vertical]. Earlier, our biggest challenge was getting other investors on board and convincing them that aging has become a place to play. Now that's a non-issue, which is great. Our job is to help the companies get other investors on board, so it's wonderful to see excitement in the space begin to build.

What are some of the other newer funds in this space? Deep Knowledge Ventures started to invest a while back, such as in Insilico Medicine. They are a part of the international community connected to the Biogerontology Research Foundation. I wouldn't call them a longevity-focused fund per se, but the principals have a strong interest in this field. Apollo Ventures on the other hand is very definitely branded as a fund involved in longevity science and interested in treating aging as a medical condition. They even launched an online magazine, Geroscience, to help propagate their point of view. This sort of advocacy for the field is one of the most cost-effective activities that venture funds can undertake. It costs them a tiny fraction of the funds they devote to their investments, and helps to expand the marketplace. When all is said and done, attention and understanding are the real goals; the ability to pull in funding is derived from those items.

Kizoo Ventures is run by Michael Greve, one of the present backers of the SENS Research Foundation agenda. The venture fund follows the Forever Healthy Foundation now in investing in companies relevant to the SENS vision of rejuvenation biotechnologies capable of repairing the damage that causes aging. Today that means senolytic therapies, and tomorrow those will be joined by other methods of damage repair such as cross-link breaking and allotopic expression of mitochondrial DNA.

This year the Methuselah Foundation launched the Methuselah Fund, an evolution of their past assistance and incubation of companies such as Organovo and Oisin Biotechnologies. This is not a traditional venture fund in that it is as much a non-profit as for-profit entity. It will be interesting to see how it progresses as new companies emerge: the organizers obviously strongly support some of the most relevant approaches to treating aging as a medical condition.

Just recently, another vocal high net worth investor launched the Juvenescence fund. It remains to be seen where exactly they will support the field, but it can't hurt to have the involvement of more businesspeople who see the worth of talking up their positions. Money doesn't grow on trees, even in times like these when the central banks are printing more than the elite can easily use. Raising funding for rejuvenation biotechnology development requires the development of a networked and interested investment community at every level, from seed funding through to raising tens of millions for the final commercial development of a therapy. Given that we're all aging, it is in everyone's interest to help those communities come into being. That very definitely means talking about the field, and the more the better.

Delivering RNA to Make Heart Cells Divide More Readily

Heart regeneration has been something of a theme this past week. Here, researchers report on a method of spurring greater cell division in the cardiomyocyte population of the heart, cells that usually divide very little. Greater division for a short period of time offers the potential of enhanced regeneration, filling out tissue with more competent cells, though it isn't terribly clear at this point what the downsides to this sort of approach might be. One reason for cells to be reluctant to replicate is that this state has evolved because it acts as defense against cancer risk, but I think the regenerative medicine field as a whole has so far demonstrated that there is a fair degree of leeway in which greater cell activity can take place without significant risk of cancer arising. If you are enthused by cell transplant therapies, then you should probably also follow work on methods to transiently accelerate replication of native cells. The near future outcomes are likely to be similar.

In the lifetime of an adult mouse or human heart, new cardiomyocytes (CMs) are generated albeit at very low rates of ~1%. On the other hand, adult zebrafish and neonatal mouse hearts can fully regenerate upon surgical resection or infarct injury. Like the zebrafish and neonatal mouse, new CMs in the adult mouse appear to arise by mitosis of pre-existing CMs, but a sufficient level of endogenous mitosis is lacking to allow for adequate regeneration and repair during disease progression. Loss of the full capacity to regenerate occurs soon after the seventh postnatal day when CMs in the neonatal mouse heart exit the cell cycle.

This highlights two key questions for the field of cardiac regeneration: (a) what holds back adult CMs from dividing and (b) can any adult CM be induced to divide? Indeed lineage tracing studies in regenerating hearts of zebrafish and neonatal mice, show that proliferation potency is achieved by cell cycle re-entry of pre-existing CMs. Consistent with this, Hippo/Yap pathway components, the transcription factor Meis1, and a series of microRNAs have been separately implicated in the regulation of CM proliferation. While the majority of CMs in adult mouse hearts permanently exit the cell cycle, a rare subset existing in relatively hypoxic microenvironment of the myocardium, retain proliferative neonatal CM features, and have smaller size, mono-nucleation and lower oxidative DNA damage. Although this specialized subset of CM may explain the ~1% endogenous proliferation capacity in the adult myocardium, it remains unexplored whether heterogeneity of the stress-response gene expression changes among the larger majority of cell cycle-arrested CMs would uncover a sub-population that could be motivated to re-enter the cell cycle.

We therefore undertook nuclear RNA sequencing of healthy and failing hearts, and uncovered the heterogeneity of CM transcriptomic stress-response. We noted distinct sub-populations of CMs and uncovered gene regulatory networks specific for each sub-population, displaying specific sub-group upregulation of cell cycle, and de-differentiation genes. Using co-expression analysis, gene networks were constructed that pointed to key long intergenic non-coding RNAs (lincRNA). Our results altogether suggest that sub-populations of adult CMs exist, and possess a unique endogenous potential for cardiac repair by the targeting of key regulator lincRNA. Further work is warranted to investigate their direct effects on cardiac regeneration.


A New Book on the History of Longevity Advocacy, a Backdrop to the Present

Ilia Stambler has published a new book on advocacy for longevity science. If you liked his last book, which is freely available online, and covered the recent history of longevity science, the past century of aspirations and efforts to address aging as a medical condition, then you should probably take a look at this one. The desire for healthy longevity has deep roots, even if half the world today seems strangely reluctant to publicly endorse the goal of living longer in good health.

This book considers the multidisciplinary aspects of longevity promotion, from the advocacy, historical, philosophical and scientific perspectives. The first part on longevity advocacy includes examples of pro-longevity campaigns, outreach materials, frequent debates and policy suggestions and frameworks that may assist in the promotion of research and development for healthy longevity. The second part on longevity history includes analyses of the definition of life-extensionism as a social and intellectual movement, the dialectics of reductionism vs. holism and the significance of the concept of constancy in the history of life extension research, an historical overview of evolutionary theories of aging, and a tribute to one of the founding figures of modern longevity science.

The third part on longevity philosophy surveys the aspirations and supportive arguments for increasing healthy longevity in the philosophical and religious traditions of ancient Greece, India, the Middle East, in particular in Islam and Judaism, and the Christian tradition. Finally, the fourth part on longevity science includes brief discussions of some of the scientific issues in life extension research, in particular regarding some potential interventions to ameliorate degenerative aging, some methodological issues with diagnosing and treating degenerative aging as a medical condition, the application of information theory for aging and longevity research, some potential physical means for life extension, and some resources for further consideration.

These discussions are in no way exhaustive, but are intended to simulate additional interest, consultation and study of longevity science and its social and cultural implications. It is hoped that this book will contribute to broadening, diversifying and strengthening the academic and public deliberation on the prospects of healthy life extension for the entire population. The setting and careful consideration of a goal may be seen as a first step toward its accomplishment.


Clearing Senescent Cells Partially Reverses Osteoporosis in Mice

Senescent cells accumulate in tissues with age, a consequence of the normal operation of cellular biochemistry. While these cells can be beneficial in small numbers and for short period of times, such as while playing a role in wound healing, it is unfortunately the case that - when present in large numbers and lingering for years - the activities of these cells contribute meaningfully to the progression of age-related disease. Their signals and other secreted molecules generate chronic inflammation, corrode tissue structure, and alter the behavior of normal cells for the worse. Senescent cells are one of the causes of aging, in other words.

Progress in the means to safely remove these cells has led to numerous studies in the past few years in which senescent cells have been shown to contribute directly to many specific age-related conditions. This well illustrates that the fastest way to make progress in understanding any given cause of aging is to find a way to selectively remove it, and see what happens. In the research results I'll point out today, the authors look at the contribution of senescent cells to the development of osteoporosis. Encouragingly, they demonstrate that the condition can be partially reversed by removing these unwanted cells, at least in mice. Past evidence suggested that this would be the case, but here the proof is much more direct, more compelling.

What is osteoporosis? In a nutshell, it is the failure of tissue maintenance in bone. In older people bone becomes weak and fragile: failing bone, failing muscle, and a failing immune system are among the most obvious and troubling components of age-related frailty. Unlike the case for most other tissues, maintenance failure in osteoporosis is an imbalance between processes of destruction and processes of creation. Bone is maintained by osteoclasts, responsible for breaking down bone tissue, and osteoblasts, responsible for building it. There is a constant dynamic balance between the removal and deposition of bone in healthy individuals, but with age that balance tilts ever more towards the osteoclasts. This isn't the only contributing factor; consider for example the role of cross-links in weakening bone by altering the structural properties of its extracellular matrix independently of the activities of osteoblasts and osteoclasts. Imbalance is significant, however.

What upsets this balance? Inflammation is one candidate, and senescent cells are well known for their ability to generate chronic inflammation. Changes in vesicle-based cell signaling are also implicated, though it is unclear as to the degree to which senescent cells can be blamed here. There are plenty of papers examining more specific proteins, signals, and aspects of cell state in osteoblasts and osteoclasts, but these are very narrow slices of the problem and not all that illuminating. It is hard to place them in the bigger picture of cause and effect. It is likely that senescent cell clearance will be a widely available therapy for osteoporosis for quite some time before the effects of aging are fully understood in this one case.

It is very promising that the research community can now forge ahead with the destruction of senescent cells in animal studies and pin down their precise contribution to many varied conditions and processes of aging. Beyond the hope for therapies that might become accessible via medical tourism in the next few years, this is a time in which many new players may be drawn to the rejuvenation research field by the existence of real, working treatments targeting a cause of aging. Some will be convinced that repair approaches such as the SENS programs, that have incorporated senescent cell clearance as a goal for the past fifteen years, are the best way forward. More funding and more support are needed if we are to see the rest of the SENS agenda for rejuvenation therapies realized just as senescent cell clearance is being realized today.

Researchers report link between cells associated with aging and bone loss

Researchers have reported a causal link between senescent cells - the cells associated with aging and age-related disease - and bone loss in mice. Targeting these cells led to an increase in bone mass and strength. "While we know from previous work that the accumulation of senescent cells causes tissue dysfunction, the role of cell senescence in osteoporosis up to this point has been unclear. The novelty of this work for the bone field lies in the fact that, rather than targeting a bone-specific pathway, as is the case for all current treatments for osteoporosis, we targeted a fundamental aging process that has the potential to improve not only bone mass, but also alleviate other age-related conditions as a group."

In the study, researchers used multiple approaches to target senescent cells in mice with established bone loss between 20 and 22 months of age. That's the equivalent of over age 70 in humans. Approaches included using: (a) a genetic model where senescent cells can be killed off; (b) a pharmacological approach, where senolytic drugs eliminate senescent cells; and (c) a Janus kinase inhibitor - a drug that blocks the activity of Janus kinase enzymes - to eliminate the toxic products produced by senescent cells. "The effects of all three approaches on aging bone were strikingly similar. They all enhanced bone mass and strength by reducing bone resorption but maintaining or increasing bone formation, which is fundamentally different from all current osteoporosis drugs."

The benefits on bone found in elderly mice were not evident in younger mice. That, coupled with the finding that the senolytic drugs were effective when given only intermittently, supports the link between senescent cells and age-related bone loss. Researchers administered a senolytic drug combination (dasatinib and quercetin) once per month to eliminate senescent cells. "Even though this senolytic drug combination was only present in the mice for a couple of hours, it eliminated senescent cells and had a long-lasting effect. This is another piece of the mounting evidence that senolytic drugs are targeting basic aging processes and could have widespread application in treating multiple chronic diseases."

Targeting cellular senescence prevents age-related bone loss in mice

Aging is associated with increased cellular senescence, which is hypothesized to drive the eventual development of multiple comorbidities. Here we investigate a role for senescent cells in age-related bone loss through multiple approaches. In particular, we used either genetic (i.e., the INK-ATTAC 'suicide' transgene encoding an inducible caspase 8 expressed specifically in senescent cells) or pharmacological (i.e., 'senolytic' compounds) means to eliminate senescent cells. We also inhibited the production of the proinflammatory secretome of senescent cells using a JAK inhibitor (JAKi).

In aged (20- to 22-month-old) mice with established bone loss, activation of the INK-ATTAC caspase 8 in senescent cells or treatment with senolytics or the JAKi for 2-4 months resulted in higher bone mass and strength and better bone microarchitecture than in vehicle-treated mice. The beneficial effects of targeting senescent cells were due to lower bone resorption with either maintained or higher bone formation as compared to control mice. In vitro studies demonstrated that senescent-cell conditioned medium impaired osteoblast mineralization and enhanced osteoclast-progenitor survival, leading to increased osteoclastogenesis.

Collectively, these data establish a causal role for senescent cells in bone loss with aging, and demonstrate that targeting these cells has both anti-resorptive and anabolic effects on bone. Given that eliminating senescent cells and/or inhibiting their proinflammatory secretome also improves cardiovascular function, enhances insulin sensitivity, and reduces frailty, targeting this fundamental mechanism to prevent age-related bone loss suggests a novel treatment strategy not only for osteoporosis, but also for multiple age-related comorbidities.

Early Steps in the Tissue Engineering of Intervertebral Discs

In this paper, researchers report on progress towards the manufacture of intervertebral discs suitable for transplantation. These tissue structures sit between the bones of the spine, the vertebrae. A sizable proportion of the population suffers at least some degree of degenerative disc disease even quite early in later life. It is one of the first serious consequences of the underlying damage that accumulates to cause aging, as well as one of the most widespread, and so there is a large potential market for practical tissue engineering or regenerative medicine solutions in this part of the field. That said, anything involving surgery and the spine isn't going to be cheap, and this is one of many areas in which therapies that can restore and repair existing tissue structures would be vastly preferable.

The intervertebral disc (IVD) is located between the vertebral bodies and is responsible for distributing forces experienced by the spinal column. It is composed of nucleus pulposus (NP) surrounded by annulus fibrosus (AF). The NP is compression resistant and rich in type II collagen and proteoglycans. The AF is comprised of multiple lamellae of angle-ply and aligned bundles of collagen fibrils, which confer the stability for spinal motion by resisting tensile forces. Adding to the complexity of the AF structure, the extracellular matrix (ECM) composition of the AF varies from the inner zone adjacent to the NP, where it is rich in proteoglycans and both type II and I collagen, to the outer zone, which is rich in type I collagen.

Replacement of the damaged disc with an in vitro formed IVD that has the functionality of a healthy disc is a reparative approach that is currently being investigated. However, recapitulating the unique architecture of the disc has been a limitation to developing this approach for clinical use. Previous studies showed that NP tissues with compressive strength can be formed scaffold free and integrated to the top surface of a porous bone substitute material such as calcium polyphosphate (CPP). The bone substitute will help anchor the implanted tissue as bone ingrowth will fix it into the bone.

AF tissue has been generated using biodegradable electrospun-aligned nanofibrous polycarbonate urethane (PU). This scaffold has the tensile strength of a native AF lamella and fiber diameters similar to the native collagen fibrils, allowing seeded AF cells to accumulate collagen aligned parallel to the scaffold. However, the successful integration of in vitro generated NP and AF tissues is crucial for it to be mechanically functional in vivo and for the longevity of the engineered IVD replacement as the NP and AF function together to resist reduction in disc height and extraneous deformation. Defective integration between in vitro engineered AF and NP tissues would resemble a fissure within a disc and thus could result in the failure of disc replacement.

Thus, the goal of engineering of an IVD replacement should be focused toward generation of a disc that can serve as a functional motion segment that recapitulates the complex architecture of the disc, exhibits the capability to withstand complex forces in vivo, and shows integration between the different tissue types in the engineered disc and with the host tissues that will be maintained postimplantation. In this study, we report the development of a two-step process to form an in vitro integrated IVD model composed of preformed multilamellated AF tissue utilizing nanofibrous aligned PU scaffolds and NP tissues formed on a bone substitute material. This tissue was characterized histologically, by immunohistochemical staining, and biomechanically. To assess integration and adherence to the bone substitute in vivo, short-term evaluation of this construct in a bovine model was performed.

This study shows that it is possible to form a model of the IVD in vitro by combining preformed AF and NP tissues. These tissues integrate and have mechanical stability. This is the first report, to the best of our knowledge, describing integration of in vitro formed AF and NP tissues and evaluation of the interfacial shear strength. The mechanism that led to this integration is unknown. A previous study that examined bioengineered cartilage-cartilage integration suggested that the matrix between the two tissues intermingle as studies showed thin collagen fibers that were produced by the bioengineered cartilage admixed with the mature collagen fibers of the native cartilage across the interface with the host tissue. The presence of both type I and II collagens at the AF-NP interface suggests that this may be occurring in this situation as well.

Interestingly, it has been proposed that the integration of distinct tissue types requires an intervening region that serves as a gradual and continuous transition in ECM properties and/or mechanical properties. In summary, this study demonstrates that it is possible to generate a model of an IVD by combining the individual tissue components and forming various interfaces with sufficient mechanical strength to be handled. The construct was present 1 month after implantation and the AF tissue was intact. Further studies are required to optimize implant fixation and scale up the disc size to evaluate its suitability as a disc replacement in an animal model.


The Processes of Atherosclerosis Damage the Heart in Addition to Blood Vessels

The end stage of atherosclerosis involves blood vessels with walls that are distorted and weakened by inflamed fatty deposits, and the vessel itself narrowed. Sooner or later something important ruptures catastrophically, causing death or serious injury. This is the outcome of a number of different, entirely ordinary biochemical processes operating over the years. These processes are also at work in the heart itself, however. When we consider efforts to clean up the root causes of atherosclerosis, such as those pioneered in the SENS research programs and elsewhere, we might also look at how that would play out in heart tissue.

What lies at the root of atherosclerosis? Firstly persistent cross-links form in the extracellular matrix of all tissues over the years, altering their structural properties. In the case of blood vessels this reduces their elasticity. Secondly, blood vessel tissues calcify with age. The causes of this are less well understood, but there are strong indications that inflammation and the growing numbers of senescent cells resident in older tissues are at fault. Like cross-linking, calcification serves to reduce elasticity. Reduced blood vessel elasticity distorts the feedback mechanisms that determine blood pressure, and the outcome is age-related hypertension. Increased blood pressure is an important component in the lethality of atherosclerosis, as it determines how readily weakened blood vessels will rupture.

Secondly, our metabolism produces an output of damaged lipids, such as those created as a consequence of cells suffering mitochondrial dysfunction. Aging and a larger number of such malfunctioning cells brings a larger flow of these damaged lipids. Ever more of them find their way into the bloodstream, where they can irritate blood vessel walls. In some cases nearby cells will overreact, or immune system cells will be damaged and overwhelmed by the lipids. There, a growing and inflammatory lesion of dead cells will start to form, sustained by a continual supply of cells turning up to try to clean up the damage - and failing, adding their remains to the problem. This is how atherosclerotic plaques start, ultimately growing so large that they harm blood flow and blood vessel structure.

Although aortic valvular sclerosis and aortic stenosis (AS) have long been thought of as two independent entities, they are now considered to be different stages of the same process. This disease manifests initially as valve thickening caused by lipocalcified deposits, leading to progressive reduction of the valve orifice which, over time, causes hemodynamically significant stenosis. Its incidence increases exponentially with age and hence was long considered a simple passive age-related degenerative process with calcium buildup. However, several studies have shown that, in addition to age, calcific aortic valve disease (CAVD) is related to the presence of cardiovascular risk factors such as male sex, arterial hypertension, diabetes mellitus, dyslipidemia, and smoking, sharing many similarities with the process that regulates atherosclerosis.

There is therefore a direct relationship between the presence of valvular calcium deposits and the development of coronary disease and cardiovascular events, to the point that some authors even consider aortic calcification a possible marker of atherosclerosis and subclinical coronary artery disease. In 1986, it was suggested that the presence of aortic alcification was a form of atherosclerosis and numerous authors have since demonstrated this fact. In the Cardiovascular Health Study, the presence of aortic sclerosis in patients without previous coronary disease increased the risk of myocardial infarction and cardiovascular mortality 1.4 and 1.5 times, respectively.

In the initial stage of the disease, there is a thickening of the valves with formation of calcium nodules that begins on the aortic valve side. These valves remain flexible for a long time, so that their opening mechanism is not affected. With the passage of time, the areas of thickening converge in large calcified masses that end up protruding into the exit tract of the aortic valve, conferring greater stiffness to the valves and significantly decreasing the valvular area, thus interfering with its normal functioning. From the microscopic point of view, there are many similarities with the lesions observed in the earliest stages of atherosclerosis. These lesions, initially interspersed with areas of normal tissue, will eventually coalesce and are characterized by disruption of the basement membrane, with areas of inflammation and cellular infiltration, deposit of atherogenic lipoproteins, and participation of the active mediators of calcification.

Lipid deposit plays an important initiator role in the cascade of cellular signaling leading to valvular calcification. The lipoproteins involved in the process include low-density lipoproteins (LDLs) and lipoprotein A. These are atherosclerosis molecules that undergo oxidation with the release of free radicals which are highly cytotoxic and also capable of stimulating inflammatory activity and mineralization. LDLs are phagocytized by macrophages, converting them into foam cells, the fundamental substrate of the atherosclerotic plaque. With progressive lipid uptake, these macrophages begin an irreversible transformation process that ends with apoptosis. Apoptosis also causes the release of factors that promote atherogenesis and progression to the complicated plaque stage, characterized by the presence of necrotic areas.

Unlike atherosclerotic plaque where the nucleus is composed of lipids associated with foam cells and areas of necrosis, in calcified valves the lipids are deposited mainly in the subendothelial zone and to a lesser extent in the deeper areas. Lipid-laden macrophages are evenly distributed in areas where there are high lipid concentrations and no areas of necrosis. In atherosclerotic plaques, the toxic accumulation of oxidized LDL causes cell death leading to plaque fracture. This is the major event that precipitates the appearance of clinically relevant symptoms. However, this mechanism has not been demonstrated in the case of CAVD, where the onset of symptoms is conditioned by the progression of calcification and increased valve rigidity.

In the more advanced phases of the disease there is remodeling of the extracellular matrix and calcification. Alteration of the matrix is promoted by the release of inflammatory cytokines. Aortic calcification is a very complex active process involving the production of proteins that promote tissue calcification. In fact, extracellular matrix proteins normally found in bone, such as osteocalcin, osteopontin, and osteonectin, can also be found in calcified valves. This presence reveals pathological calcification and bone formation at the valve level. In short, this process involves different mechanisms of bone mineralization and resorption.

In conclusion, CAVD is highly prevalent. Long understood as a passive process, it is now known to be complex and one which involves pathophysiological mechanisms similar to those of atherosclerosis. Understanding these mechanisms could help to establish new therapeutic targets that might allow us to halt or at least slow down the progression of the disease.


Exercise Restores Failing Autophagy in Damaged Heart Tissue

Despite the very promising progress in aging research that has taken place since the turn of the century, it remains the case that exercise and calorie restriction are still the most reliable and beneficial methods of improving long-term health and life expectancy. That should cease to be true a few years from now when the first senolytic drug candidates are better categorized and more easily available, but for today the oldest of free methodologies have a better expectation value than anything you might consider paying for. Precisely because these effects are reliable, and to a lesser degree because present medical approaches to treating age-related disease are expensive and marginal, the research community is interested in reverse engineering the changes in metabolism brought on by exercise and calorie restriction. The goal is to find ways to induce at least some of these changes independently of lifestyle choices, as a therapy.

The pharmaceutical development of calorie restriction mimetics has been ongoing in earnest for more than a decade, but there isn't yet much to show for it when it comes to practical treatments. The biochemistry is enormously tangled and complex, since calorie restriction changes just about everything in cellular metabolism that looks like it might be relevant to health and aging. Exercise is only marginally less challenging to investigate, but less work has gone into that end of the field to date, and so it lags further behind. Still, some general conclusions can be drawn from the evidence to date, one of which is that increased autophagy is an important component of the benefits.

Autophagy is a collection of processes responsible for clearing out debris and damaged inside cells: broken proteins, unwanted chemicals, and damaged cell structures. These are tagged, sometimes encapsulated in a membrane, and then hauled off for disassembly. It is clearly the case that more autophagy is good, based on the small mountain of evidence that exists to back up that claim, and this is presumably the case because more aggressive autophagy results in less damage present in cells at any given moment in time. Less damage means less of a chance for that damage to produce other, lasting consequences. Many of the scores of methods that modestly slow aging in laboratory species result in individuals that exhibit increased autophagy. Calorie restriction fails to produce its benefits when autophagy is selectively disabled. And so on. There is a portion of the field somewhat related to calorie restriction and exercise research in which boosted autophagy is investigated as a potential basis for therapies - though just like the development of calorie restriction and exercise mimetics, there is very little of practical use to show for the past ten years of work.

The research results noted here can be added to the long list of those that point towards autophagy as an important component in the way in which exercise produces improvements in long-term health. This is particulary true of autophagy that targets damaged mitochondria. The consensus in the research community is that mitochondrial damage plays an important role in the progression of aging, though there is considerable debate over the details. Anything that can cut back on the pace at which cells become taken over by dysfunctional mitochondria should as a consequence slow down aging.

Better autophagy is nowhere near as good as the sort of rejuvenation biotechnology solutions proposed by the SENS Research Foundation and others - any level of autophagy will still be subverted by suitably broken mitochondria to some degree - but it is better than nothing. The bounds of the possible for increased autophagy are amply demonstrated by the difference between people who take care of themselves and people who don't. You gain a few years in health life expectancy. You can't reliably exercise your way into living in good health until 100, and you'll still be frail and diminished even if you are one of the few who makes it that far. Exercise mimetics are unlikely to produce radically larger results. Only future repair therapies after the SENS model, those that can target and remove a large fraction of the damage that causes aging, such as every last dysfunctional mitochondrion, can possibly provide significantly more than just a slight slowing of aging.

Research reveals how physical exercise protects the heart

Regular exercise is now considered an important form of treatment for heart failure, a condition in which the heart is unable to pump enough blood to meet the body's needs. The benefits of exercise range from prevention of cachexia - severe loss of weight and muscle mass - and control of arterial blood pressure to improved cardiac function, postponing a degenerative process that causes progressive heart cell death. About 70% of heart failure patients die from the condition within five years. A recent study helps to elucidate part of the mechanism whereby aerobic exercise protects the sick heart.

"Basically, we discovered that aerobic training facilitates the removal of dysfunctional mitochondria from heart cells. The removal of dysfunctional mitochondria increases the supply of ATP, the molecule that stores energy for the cell, and reduces the production of toxic molecules, such as oxygen free radicals and reactive aldehydes, an excess of which damages the cell structure." The long-term aim of the research is to identify intracellular targets that can be modulated by drugs to produce at least some of the cardiac benefits obtained by means of physical exercise. "Evidently, we don't aim to create an exercise pill, which would be impossible because exercise acts at many levels and throughout the organism, but it might be feasible for a drug to mimic or maximize the positive effect of physical activity on the heart."

In a previous study the group showed through experiments with rats that aerobic training reactivates the proteasome, an intracellular complex responsible for cleansing cells of damaged proteins. The results also showed that proteasome activity in the heart of a patient with heart failure decreases by more than 50% and that, as a result, highly reactive proteins build up in the cytoplasm, where they interact with other structures and cause heart cell death. In the recently published article the group showed that exercise also regulates the activity of another cellular cleansing mechanism, known as autophagy. "Instead of degrading isolated proteins, this system creates a vesicle, an autophagosome, around dysfunctional organelles and transports all this material at once to the lysosome, a sort of incinerator. The lysosome contains enzymes that destroy cell waste. However, we observed that autophagic flux is interrupted in the heart of a rat with heart failure and that there's a buildup of dysfunctional mitochondria."

The mitochondria may even divide to isolate the damaged part and facilitate its removal. The researchers were able to observe this by analyzing the activity of proteins related to the process of mitochondrial division. However, the system that should transport the rejects to the lysosome is unable to complete the task. When the researchers analyzed heart tissue from a rat model of heart failure, they found that the cells contained large clusters of small fragmented mitochondria. This was not observed in the group of healthy rats. These mitochondria were placed in an apparatus that measured oxygen consumption and hence assessed mitochondrial metabolism. The test confirmed that the mitochondrial respiration was not functioning properly.

"The images showed that membranes were trying to form around these small mitochondria, but the autophagosome failed to surround them completely. We concluded that they were accumulating because the removal system wasn't working. The rats were placed on the treadmill, and the dysfunctional mitochondria disappeared. The exercise restored the process of dysfunctional cardiac mitochondria removal. The benefits of exercise were abolished when we blocked autophagy pharmaceutically or genetically. Our hypothesis is that physical training modulates the expression and/or activity of one or more key proteins involved in mitophagy, or mitochondrial autophagy, thereby restoring its activity. We're now trying to confirm this hypothesis."

Exercise reestablishes autophagic flux and mitochondrial quality control in heart failure

We previously reported that facilitating the clearance of damaged mitochondria through macroautophagy/autophagy protects against acute myocardial infarction. Here we characterized the impact of exercise, a safe strategy against cardiovascular disease, on cardiac autophagy and its contribution to mitochondrial quality control, bioenergetics and oxidative damage in a post-myocardial infarction-induced heart failure animal model.

We found that failing hearts displayed reduced autophagic flux depicted by accumulation of autophagy-related markers and loss of responsiveness to chloroquine treatment at 4 and 12 weeks after myocardial infarction. These changes were accompanied by accumulation of fragmented mitochondria with reduced O2 consumption, elevated H2O2 release and increased Ca2+-induced mitochondrial permeability transition pore opening. Of interest, disruption of autophagic flux was sufficient to decrease cardiac mitochondrial function in sham-treated animals and increase cardiomyocyte toxicity upon mitochondrial stress.

Importantly, 8 weeks of exercise training, starting 4 weeks after myocardial infarction at a time when autophagy and mitochondrial oxidative capacity were already impaired, improved cardiac autophagic flux. These changes were followed by reduced mitochondrial number:size ratio, increased mitochondrial bioenergetics and better cardiac function. Moreover, exercise training increased cardiac mitochondrial number, size and oxidative capacity without affecting autophagic flux in sham-treated animals.

Further supporting an autophagy mechanism for exercise-induced improvements of mitochondrial bioenergetics in heart failure, acute in vivo inhibition of autophagic flux was sufficient to mitigate the increased mitochondrial oxidative capacity triggered by exercise in failing hearts. Collectively, our findings uncover the potential contribution of exercise in restoring cardiac autophagy flux in heart failure, which is associated with better mitochondrial quality control, bioenergetics and cardiac function.

A Successful Trial of Gene Therapy to Spur Vascular Growth in Heart Disease

One approach to the structural damage that takes place in heart disease is to attempt to spur growth of new blood vessels, to deliver nutrients to heart tissue that is currently poorly supplied. Gene therapy is in principle well suited to this goal, as a range of genes are known to be involved in regulating the processes of blood vessel generation. So far attempts to create a viable treatment haven't gone so well, unfortunately, but here researchers report success in a recent trial. The results seem promising. At the high level, this approach doesn't address the underlying causes of the situation, the various degenerative processes that give rise to heart disease and structural failure of important tissues in the first place, but when effective it might be considerably better than doing nothing, at least in the near term of a few months or years of remaining life expectancy for these patients.

Angina pectoris is the most common symptom of coronary artery disease (CAD). In spite of improved medical and revascularization therapies, 5-10% of patients undergoing coronary angiography have refractory angina (RA), i.e. they are severely symptomatic while on optimal medical therapy and prior revascularization and not amenable to further revascularization procedures. Some patients with CAD develop collateral arteries, which can rescue ischaemic myocardium in spite of significant occlusions in coronary arteries and alleviate ischaemic symptoms. Therapeutic vascular growth stimulates this natural process and offers a potential new treatment for RA. However, most previous cardiovascular proangiogenic trials have been unsuccessful. This is likely due to (i) poor gene transfer efficiency in the myocardium, (ii) tested growth factors may not have been the most optimal ones, and (iii) inability to target therapy into ischaemic, but viable myocardium.

To address these challenges, we used PET perfusion imaging and an electromechanical catheter system for gene transfer to identify ischaemic, hibernating myocardium with the lowest perfusion reserve for the targeted therapy. For the first time, we also used VEGF-DΔNΔC, a new member of the VEGF family that stimulates both angiogenesis and lymphangiogenesis. In addition, because Lp(a) is associated with pro-atherogenic, pro-inflammatory, and pro-thrombotic effects, elevated plasma levels were tested as a potential new biomarker to identify patients who might benefit from the induced therapeutic vascular growth.

Thirty patients with severe RA were randomized 4:1 to VEGF-DΔNΔC therapy (AdVEGF-D group) and placebo (controls) in blocks of five patients. To select optimal sites for gene injections, the left ventricle was mapped to detect areas of viable myocardium with reduced contraction. Coronary angiography and PET imaging were used to confirm viable myocardial segments with impaired myocardial perfusion reserve (MPR). In the AdVEGF-D group, MPR of the treated area increased from 1.00 ± 0.36 at baseline to 1.31 ± 0.46 at 3 months and to 1.44 ± 0.48 at 12 months. Myocardial perfusion reserve of the reference area (myocardium with the highest MPR at baseline) showed no significant change. On the contrary, it tended to decrease by 10.7% at 3 months and 8.8% at 12 months. Myocardial perfusion reserve in the control group showed no significant change from baseline to 3 and 12 months.

A potential impact of elevated Lp(a) was also noted in the response of the RA patients to this therapy, with the most benefit in patients with the highest Lp(a) levels. This is consistent with a recent report that 50% of patients with RA have elevated Lp(a), and in whom Lp(a) lowering achieved by lipid apheresis was associated with objective evidence of myocardial blood flow improvement by MRI and significant relief of RA symptoms.


Bacteria Promote Cancer by Enhancing Stem Cell Replication and Turnover

Bacterial infection has been linked to cancer risk in some cases, and here researchers propose that this is because the bacterial species can cause some stem cell populations to replicate more frequently. Greater cell activity in this fashion over time raises the risk of a cancerous mutation occurring. The authors of the study examine only the one case in which a bacteria-cancer association is well studied, but we might speculate on similar situations elsewhere in the body.

While it has long been recognized that certain viruses can cause cancer by inserting oncogenes into the host cell DNA, the fact that some bacteria can also cause cancer has been slower to emerge and much harder to prove. While it is now clear that most cases of stomach cancer are linked to chronic infections with H. pylori, the mechanism remains unknown. Researchers have spent many years investigating this bacterium and the changes it induces in the cells of the stomach epithelium. In particular, they were puzzled how malignancy could be induced in an environment in which cells are rapidly replaced.

It was suspected that the answer might lie in the stem cells found at the bottom of the glands that line the inside of the stomach, which continually replace the remaining cells 'from the bottom up' - and which are the only long-lived cells in the stomach. Researchers have now overturned the established dogma to show that H. pylori not only infects the surface cells, which are about to be sloughed off, but that some of the bacteria manage to invade deep into the glands and reach the stem cell compartment. They have now found that these stem cells do indeed respond to the infection by increasing their division - producing more cells and leading to the characteristic thickening of the mucosa observed in affected patients.

The researchers used different transgenic mice to trace cells expressing particular genes, as well as all their daughter cells. The results indicate that the stomach glands contain two different stem cell populations. Both respond to a signalling molecule called Wnt, which maintains stem cell turnover in many adult tissues. Crucially, they discovered that myofibroblast cells in the connective tissue layer directly underneath the glands produce a second stem cell driver signal, R-spondin, to which the two stem cell populations responded differently. It is this signal, which turned out to control the response to H. pylori: Following infection, the signal is ramped up, silencing the more slowly cycling stem cell population and putting the faster cycling stem cell population into overdrive.

These findings substantiate the rising awareness that chronic bacterial infections are strong promoters of cancer. 'Our findings show that an infectious bacterium can increase stem cell turnover. Since H. pylori causes life-long infections, the constant increase in stem cell divisions may be enough to explain the increased risk of carcinogenesis observed. Our new findings shed light on the intriguing ways through which chronic bacterial infections disturb tissue function and provide invaluable clues on how bacteria, in general, may increase the risk of cancer'.


Cell Banking for Future Autologous Cell Therapies Seems Pointless

I'll start here by pointing out the most useful application for cryopreservation of cells and tissues: it greatly reduces the cost of logistics in transplant medicine. When you need to coordinate people and cells and places on timescales of a few days, weeks, or months, the ability to confidently put the cells into safe storage for short period of time changes the whole tenor of the affair. Just look at the organ transplant field, for example, which is defined by the fact that this storage cannot yet be achieved. Organ transplantation is enormously expensive not just because the donor pool is limited, but also because organs cannot be kept alive and useful for very long outside the body. When the state of reversible tissue crypopreservation advances to permit reliable vitrification and restoration of whole organs, the whole field of transplantation will change dramatically. That change in logistics has already taken place for applications involving cells, such as fertility biotechnology, but long enough ago that most of us probably don't appreciate the magnitude of the difference between before and after.

A recent startup, Forever Labs, is aiming at an application of cell cryopreservation that I think is much less useful. This is the practice of banking cells, particularly stem cells, in the hope of using them in cell therapies in the more distant future, decades away. The theory here is that you are banking today's less damaged cells, and because they are less damaged they will be more helpful in medical applications than the worn set of cells you'll possess twenty years and a lot more damage down the line:

Forever Labs preserves young stem cells to prevent your older self from aging

Forever Labs, a startup in Y Combinator's latest batch, is preserving adult stem cells with the aim to help you live longer and healthier. Stem cells have the potential to become any type of cell needed in the body. It's very helpful to have younger stem cells from your own body on hand should you ever need some type of medical intervention, like a bone marrow transplant as the risk of rejection is greatly reduced when the cells are yours. The founder spent the last 15 years studying stem cells. What he found is that not only do we have less of them the older we get, but they also lose their function as we age. So, he and his co-founders started looking at how to bank them while they were young.

The founder banked his cells two years ago at the age of 38. So, while he is biologically now age 40, his cells remain the age in which they were harvested - or as he calls it, "stem cell time travel." Stem cell banking isn't new. In fact, a lot of parents are now opting to store their baby's stem cells through cord blood banking. But that's for newborns. For adults, it's not so common, and there's a lot of snake oil out there.

The process involves using a patented device to collect the cells. Forever Labs can then grow and bank your cells for $2,500, plus another $250 for storage per year (or a flat fee of $7,000 for life). The startup is FDA-approved to bank these cells and is offering the service in seven states. What it does not have FDA approval for is the modification of those cells for rejuvenation therapy. The founders refer to what the company is doing as longevity as a service, with the goal being to eventually take your banked cells and modify them to reverse the biological clock. But that may take a few years. There are hundreds of clinical trials looking at stem cell uses right now. Forever Labs has also proposed its own clinical trial to take your stem cells and give them to your older cells.

To me banking cells for future cell therapy sounds pointless. It is, in effect, a bet against progress in applied cell biotechnology - and given the revolutionary pace of advancement in all areas of biotechnology, this appears a poor wager from where I stand. Is it to be imagined that two decades from now it will not be possible to engineer youthful or sufficiently-youthful-like cells from old skin samples? The process of producing induced pluripotent stem cells is already known to be capable of reverting a number of aspects of aged cells, such as mitochondrial issues. Tinkering with epigenetic markers, such as those that differ between cells from old and young tissues, is a going concern: gene therapy of all sorts will explode in size and capability over the decades ahead. Age-related metabolic waste inside cells can be diluted through replication. Correcting stochastic mutations in cell samples is in principle as straightforward as picking out different cell lineages and comparing their genomes to find the root genome prior to those mutations, and then applying CRISPR. Today that's a feasible lab project given some funding. Twenty years from now colleges will be running that as an afternoon lesson on the student's personal lab desk machines in CellBio 201. In the absolute worst case, use somatic cell nuclear transfer to put patient DNA into a pristine cell, and establish a new line that way.

Progress isn't all that we should consider here, however. Suppose that the cell banking wager pays off, and biotechnology somehow magically fails to advance meaningfully over the next two decades. Lucky you, now the beneficiary of younger, less damaged cells that can be used for cell therapy. But with the technology of cell therapies as they stand now or next year, what can you really do with those cells? The answer is nothing that is more than somewhat beneficial, meaning the present panoply of more reliably effective stem cell transplants and cell therapies. All of those potential uses, so far as can be seen to date, are more or less as effective when employing the cells of an old individual. So far the only signs that young cells would be significantly better occur in cases where those cells are taken from individuals shortly after birth, or before. But even there, this is a question of cell signaling and cell state, something that researchers are hotly engaged in deciphering even now: just how likely is it that they will have failed to replicate these mechanisms a few decades from now?

So it seems to me that the only way in which banking your stem cells makes sense is if biotechnology progresses extremely selectively: a complete failure to understand and control cell state any more effectively than today, coupled with radical strides in the capabilities of cell therapies. Since the latter strongly depends on the former, I'd say that this future isn't going to come to pass. Therefore it really doesn't make much sense to bank cells for future therapeutic use based on the idea that relative levels of age-related cell damage will make a significant difference.

Towards Efficiency in Uncovering all Potential Longevity-Altering Substances

The research community is moving, slowly and incrementally, towards a world in which drug libraries become vastly larger and more useful because it should be possible to use computational techniques to far more efficiently (a) predict the effects of specific compounds on specific biological mechanisms, and (b) design similar, better compounds. Much of the trial and error, and thus most of the cost of drug discovery will go away. The result will be a pharmaceutical development processes that is still definitely of a trial and error nature at its core, but much more informed, far removed from the blind fumbling and chance discovery of the past. Insilico Medicine is a business community example of progress towards this goal, and the open access paper noted here is an example of analogous research community work.

Does this mean we should expect the near-term emergence of longevity-enhancing drugs based on the adjustment of metabolic state that are vastly more effective than rapamycin analogs? I think no. My thesis is that the effectiveness of these drugs is far more constrained by the lack of plasticity of human longevity in response to metabolic alteration than it is by the quality of the drug. Exercise and calorie restriction mimetics have a limited upside in terms of what they can do for us.

Where pharmaceutical approaches do prove to have larger and more reliable effects on longevity, it will be because they are producing true repair of the causes of aging rather than mere metabolic adjustment. Examples include removal of senescent cells, or breaking down forms of metabolic waste ranging from cross-links to amyloids to the constituents of lipofuscin that accumulate in lysosomes. Here, better drug development processes will lead to an improved pipeline of drug candidates that are more efficient at specific damage repair tasks. This is where upgrades in the infrastructure of the traditional pharmaceutical pipeline can shine. Now if only more groups were intent on this path rather than trying to find a marginally better alternative to rapamycin...

Old age is the greatest risk factor for many diseases, including various types of cancer, inflammatory and neurodegenerative diseases. Traditional medical science combats one disease at a time, instead of combating the underlying biological ageing process that leads to many age-related diseases. From a whole body system's point of view, this traditional one-disease-at-a-time approach focuses on the downstream diseases, rather than considering the underlying mechanisms of age-related functional decline. This approach has limited effectiveness at present and is likely to be less effective in the future, because of an increasingly larger elderly population suffering from multiple age-related diseases. In contrast, interventions that slow down ageing and promote "healthy ageing" could in principle delay the onset of all age-related diseases, with a significant benefit to human health and a large reduction of healthcare costs.

Pharmacological interventions are arguably the most practical ageing intervention for humans, avoiding the main problems with genetic interventions (generally unethical in humans) and dietary interventions such as caloric restriction, which are difficult to maintain for the vast majority of people. For instance, there is currently great interest in discovering drugs that mimic the process of caloric restriction. In addition, promising research on pharmacological interventions on the ageing process is underway at the National Institute of Aging's Intervention Testing Program (ITP), which consists of administering drugs or chemical compounds to mice under carefully controlled conditions. However, as mouse experiments are costly and time consuming, so far only a limited number of drugs or compounds have been evaluated. Thus, using simpler model organisms for evaluating a chemical compound's effect on an organism's lifespan is appealing, and a substantially larger number of studies have administered compounds to C. elegans than other organisms. As the ITP for mice, the Caenorhabditis Intervention Testing Program has been introduced for assessing longevity variation for chemical compounds.

In this work we analyse data from the DrugAge database, which contains information about chemical compounds and their effect on the lifespan of organisms. DrugAge contains a variety of compounds with anti-ageing properties such as gerosuppressant, geroprotective and senolytic activity as well lifespan increasing properties for a specific species. In order to analyse such data, we use random forests, which is a supervised machine learning method. In this work, the random forest builds a classification model to predict whether or not a chemical compound will increase the lifespan of C. elegans, based on predictive features describing that compound. The best model produced by the random forest method was applied to a screening "external" dataset with compounds from the DGIdb database, where the effect of the compounds on an organism's lifespan is unknown. The predictions of that model were used to identify the "top hit" compounds in the DGIdb dataset, i.e. compounds with higher probabilities of increasing lifespan in C. elegans.

In conclusion we have built, using machine learning, a model to predict the longevity effects of chemical compounds in C. elegans, using the recently published DrugAge dataset. The list of top-hit compounds and their analysis contributes to our knowledge of likely longevity-extending compounds, and experimental confirmation of these predictions would be an interesting direction for future research.


An Injected Tissue Engineered Heart Patch

Tissue engineers are still limited in the size of tissues they can produce, as there remains no reliable solution for the generation of capillary networks. The thickness of tissue that can be constructed is thus limited to the distance that nutrients can perfuse in the absence of capillaries. The production of thin sheets is viable under these constraints, and a number of research groups are investigating methods of spurring heart regeneration by applying a sheet - a patch - of suitable cells onto the exterior of this organ. The research noted here is an example of the type, merging this line of work with efforts to produce tissue scaffolds that can be injected, rather than requiring surgery to implant.

Repairing heart tissue destroyed by a heart attack or medical condition with regenerative cells or tissues usually requires invasive open-heart surgery. But now researchers have developed a technique that lets them use a small needle to inject a repair patch a little smaller than a postage stamp, without the need to open up the chest cavity. The team are experts in using polymer scaffolds to grow realistic 3D slices of human tissue in the lab. One of their creations, AngioChip, is a tiny patch of heart tissue with its own blood vessels - the heart cells even beat with a regular rhythm.

Such lab-grown tissues are already being used to test potential drug candidates for side effects, but the long-term goal is to implant them back into the body to repair damage. "If an implant requires open-heart surgery, it's not going to be widely available to patients. It's just too dangerous." After a heart attack the heart's function is reduced so much that invasive procedures like open-heart surgery usually pose more risks than potential benefits.

The researchers spent nearly three years developing a patch that could be injected, rather than implanted. After dozens of attempts, they found a design that matched the mechanical properties of the target tissue, and had the required shape-memory behaviour: as it emerges from the needle, the patch unfolds itself into a bandage-like shape. The shape-memory effect is based on physical properties, not chemical ones. This means that the unfolding process doesn't require additional injections, and won't be affected by the local conditions within the body. Over time, the scaffold will naturally break down, leaving behind the new tissue.

The next step was to seed the patch with real heart cells. After letting them grow for a few days, the team injected the patch into rats and pigs. Not only does the injected patch unfold to nearly the same size as a patch implanted by more invasive methods, the heart cells survive the procedure well. "When we saw that the lab-grown cardiac tissue was functional and not affected by the injection process, that was very exciting. Heart cells are extremely sensitive, so if we can do it with them, we can likely do it with other tissues as well." The team also showed that injecting the patch into rat hearts can improve cardiac function after a heart attack: damaged ventricles pumped more blood than they did without the patch.


Macrophages Showing Markers of Cellular Senescence may not be Senescent Cells

Cellular senescence is one of the causes of aging: rising numbers of cells fall into a harmful senescent state and then linger there. The activities of these cells directly contribute to loss of tissue function and the progression of many age-related diseases. You might recall last year's investigations into possible cellular senescence in the immune system, focused on macrophages that exhibit some of the markers used to identify senescent cells. Does this mean that part of the macrophage population is in fact senescent in older people, and they would benefit from the removal of those cells, as is the case for other senescent cell types, or does it mean something else entirely, and these cells may not be harmful? In the open access paper here, the author's of last year's study suggest that the latter situation is the case, though whether or not these cells are damaging to an individual remains to be determined.

The markers in question here are p16 (also known as p16ink4a) and senescence-associated β-galactosidase (SAβG). If we approach this from the point of view of concern that treatments might be destroying cells unnecessarily, then SAβG isn't all that relevant, as I'm not aware of any group that actually targets that signal, versus only using it for assessment purposes. The companies that are developing pharmaceuticals to destroy senescent cells are not doing so in a way that specifically targets raised expression of these genes: drug development starts with a drug found in the compound libraries that is somewhat useful in killing the cells you want it to kill, and then you try to improve upon whatever it turns out to do under the hood. That mechanism doesn't have any necessary connection to the markers that the research community has developed to identify senescent cells.

On the other hand p16 is one of the targets used by Oisin Biotechnologies, and their gene therapy absolutely does recognize specific genes and and their expression levels, and selects cells for destruction on that basis. The Oisin team will in the course of their development find out one way or another whether or not removal of p16-expressing macrophages is useful. We might also recall that the earlier studies of mice genetically engineered to clear senescent cells used p16 as the identifying marker for cell destruction. Clearly the benefits there were achieved with a clean sweep of p16-expressing macrophages as well as other senescent cells, even if it can be argued that those macrophages are not senescent in the way we'd consider other cell types to be senescent.

The broader point raised in the paper here is that a refinement is needed in the current taxonomy of cellular senescence, especially in how it relates to markers that are coming to be understood as perhaps less specific than was originally hoped. That seems a fair enough comment on the current state of the research. I think that this desired progress will arrive, and fairly quickly now that senescent cells - as defined by various measures and markers - can be destroyed reliably and effectively. The size of the effects on health and life span in rodents obtained so far are large enough that future animal studies should fairly conclusively settle whether or not certain cell populations are bad and should be removed.

p16(Ink4a) and senescence-associated β-galactosidase can be induced in macrophages as part of a reversible response to physiological stimuli

The accumulation of p16Ink4a-positive cells is observed in aged mice, and their eradication has been linked to certain improvements in the health state of older animals consistent with rejuvenation. Even though p16Ink4a-positive cells in vivo have been assumed to be senescent, little evidence exists to directly support this assumption. Our previous work identifying macrophage subtypes that co-express markers conventionally assigned to senescent cells (SCs), p16Ink4a/SAβG, has prompted additional interpretations of previously published experimental data regarding the role of p16Ink4a-positive cells in aging and age-related diseases.

As such, defining the exact nature of p16Ink4a-positive cells is crucial for proper development of therapeutics for the prevention and treatment of aging and age-related diseases. Today, the field of aging is focused on the development of senolytic compounds that are isolated for their ability to selectively kill SCs generated in vitro. If these cells are different from p16Ink4a-positive cells accumulating in vivo with age, this could misdirect both academic studies of senescence as a phenomenon, as well as practical efforts to develop anti-aging therapeutics. These considerations motivated our present work, which was aimed at defining the nature of p16Ink4a-positive cells found in mouse tissues in vivo and their relation to the phenomenon of cellular senescence.

What is "cellular senescence"? Currently, all definitions agree that SCs cease to proliferate. However, this parameter is not sufficient to define SCs since this is also the property of terminally differentiated cells. One apparent difference is that terminal differentiation occurs in response to various physiological stimuli, while induction of senescence almost always occurs in response to genotoxic stress. Accordingly, the onset of senescence commonly involves p53, a major universal genotoxic stress response mechanism that triggers cell cycle arrest, the first step in conversion to senescence. Another intrinsic property of the senescent phenotype is that it is not reversible through known physiological stimuli, only occurring through the acquisition of genetic mutation or epigenetic modulations. Thus, a more precise definition of SCs should include those cells that irreversibly cease to proliferate following genotoxic stress. Currently, none of the other properties of SCs that are being used for their recognition, such as p16Ink4a- or SAβG-positivity, are sufficiently specific for SCs as to be essential components of this definition.

We previously demonstrated that a significant proportion of p16Ink4a/SAβG-positive cells in the fat tissue of older mice are of hematopoietic origin, express surface markers of macrophages and are capable of phagocytosis. Here, we demonstrate that these cells appear and accumulate independently of their p53 status. Furthermore, induction of p16Ink4a/SAβG markers can be significantly modulated (in both directions) by physiological stimuli known to polarize macrophages. In recent literature, a role for p16Ink4a has been implicated in macrophage physiology with no relation to other properties of senescence. For example, p16Ink4a expression is induced during monocyte differentiation into macrophages in vitro without affecting the cell cycle, and macrophages from p16Ink4a-deficient mice are skewed towards an M2 phenotype, exhibiting defects in M1 polarization response.

In summary, we conclude that a significant proportion of p16Ink4a/SAβG-positive cells accumulating in aging mice are macrophages that acquired this phenotype as part of their physiological reprogramming towards an M2-like phenotype. This interpretation is consistent with reports that tumor-associated macrophages (TAMs), which possess also an M2 phenotype, were shown to express p16Ink4a. It is highly unlikely that senolytic compounds isolated for their ability to eradicate bona fide SCs would be equally potent and selective against cells that simply resemble SCs by two unreliable biomarkers (p16Ink4a/SAβG) yet lack the most definitive properties of senescence. However, several molecules identified with anti-SC activities, including ruxolitinib, dasatinib, and quercetin, have documented anti-inflammatory effects on macrophages that may contribute to improvements in healthspan. We believe that the assumptions made in a series of recent works - that p16Ink4a/SAβG-positive cells are SCs - needs to be carefully re-evaluated, and that the effects of anti-SC therapies on macrophages needs to be evaluated.

Importantly, our results do not overthrow the significance of the SC's role in aging or disprove the rationale for the development of senolytic compounds. Nevertheless, they do question the accuracy of interpretation of the reasons for the improvement of the health of mice following the eradication of p16Ink4a-positive cells, raising the possibility that SCs may not be the only ones implicated in age-related frailty and that other players may be involved that could require different approaches to target.

Activating Hair Follicle Stem Cells to Enhance Hair Growth

This work, I think, is not significant for the hair growth, but for the fact that the researchers involved have found a simple way to enhance the activity of a stem cell population. It suggests that the research community might expect to find analogous (but probably quite different) simple ways to selectively achieve the same outcome in other stem cell populations that support other tissue types. Losing hair is somewhere in the vicinity of inconvenient and annoying. There are any number of other tissues in which the age-related decline of stem cell activity is ultimately fatal, and those seem to me to be the more important challenges to focus upon.

Hair follicle stem cells are long-lived cells in the hair follicle; they are present in the skin and produce hair throughout a person's lifetime. They are quiescent, meaning they are normally inactive, but they quickly activate during a new hair cycle, which is when new hair growth occurs. The quiescence of hair follicle stem cells is regulated by many factors. In certain cases they fail to activate, which is what causes hair loss.

Researchers found that hair follicle stem cell metabolism is different from other cells of the skin. Cellular metabolism involves the breakdown of the nutrients needed for cells to divide, make energy and respond to their environment. The process of metabolism uses enzymes that alter these nutrients to produce metabolites. As hair follicle stem cells consume the nutrient glucose - a form of sugar - from the bloodstream, they process the glucose to eventually produce a metabolite called pyruvate. The cells then can either send pyruvate to their mitochondria - the part of the cell that creates energy - or can convert pyruvate into another metabolite called lactate. "Our observations about hair follicle stem cell metabolism prompted us to examine whether genetically diminishing the entry of pyruvate into the mitochondria would force hair follicle stem cells to make more lactate, and if that would activate the cells and grow hair more quickly."

The research team first blocked the production of lactate genetically in mice and showed that this prevented hair follicle stem cell activation. Conversely, they increased lactate production genetically in the mice and this accelerated hair follicle stem cell activation, increasing the hair cycle. "Before this, no one knew that increasing or decreasing the lactate would have an effect on hair follicle stem cells. Once we saw how altering lactate production in the mice influenced hair growth, it led us to look for potential drugs that could be applied to the skin and have the same effect."

The team identified two drugs that, when applied to the skin of mice, influenced hair follicle stem cells in distinct ways to promote lactate production. The first drug, called RCGD423, activates a cellular signaling pathway called JAK-Stat, which transmits information from outside the cell to the nucleus of the cell. The research showed that JAK-Stat activation leads to the increased production of lactate and this in turn drives hair follicle stem cell activation and quicker hair growth. The other drug, called UK5099, blocks pyruvate from entering the mitochondria, which forces the production of lactate in the hair follicle stem cells and accelerates hair growth in mice.


A Hair Follicle Recipe for Skin Organoids

Researchers here describe a new recipe for guiding skin cells to form organoids and generate hair follicles. A fair amount of tissue engineering is the search for reliable recipes, different for every tissue type. Once established such recipes can be used to enable the production of specific cell and tissue types for research and transplantation, or to inform the development of therapies to encourage the same processes of regrowth to take place in the body, without the need for transplantation.

How does the skin develop follicles and eventually sprout hair? A new study addresses this question using insights gleaned from organoids, 3D assemblies of cells possessing rudimentary skin structure and function - including the ability to grow hair. Scientists started with dissociated skin cells from a newborn mouse and then took hundreds of timelapse movies to analyze the collective cell behavior. They observed that these cells formed organoids by transitioning through six distinct phases: 1) dissociated cells; 2) aggregated cells; 3) cysts; 4) coalesced cysts; 5) layered skin; and 6) skin with follicles, which robustly produce hair after being transplanted onto the back of a host mouse. In contrast, dissociated skin cells from an adult mouse only reached phase 2 - aggregation - before stalling in their development and failing to produce hair.

To understand the forces at play, the scientists analyzed the molecular events and physical processes that drove successful organoid formation with newborn mouse cells. At various time points, they observed increased activity in genes related to: the protein collagen; the blood sugar-regulating hormone insulin; the formation of cellular sheets; the adhesion, death or differentiation of cells; and many other processes. In addition to determining which genes were active and when, the scientists also determined where in the organoid this activity took place. Next, they blocked the activity of specific genes to confirm their roles in organoid development.

By carefully studying these developmental processes, the scientists obtained a molecular "how to" guide for driving individual skin cells to self-organize into organoids that can produce hair. They then applied this "how to" guide to the stalled organoids derived from adult mouse skin cells. By providing the right molecular and genetic cues in the proper sequence, they were able to stimulate these adult organoids to continue their development and eventually produce hair. In fact, the adult organoids produced 40 percent as much hair as the newborn organoids - a significant improvement. "Normally, many aging individuals do not grow hair well, because adult cells gradually lose their regenerative ability. With our new findings, we are able to make adult mouse cells produce hair again. In the future, this work can inspire a strategy for stimulating hair growth in patients."


Oxidative Stress and Cellular Senescence in the Progression of Osteoarthritis

Osteoarthritis is a common age-related degenerative joint condition in which cartilage and bone are lost, though in the earlier stages of the condition, changes in cartilage are more subtle and complicated in their effects. While not traditionally seen as an inflammatory condition, as there is no evident, visible joint inflammation as occurs in other forms of arthritis, there is nonetheless a strong case for considering osteoarthritis to be driven by localized inflammation. Recently, the increased number of senescent cells in aged joint tissue has been shown to contribute directly to the development of osteoarthritis. Indeed, osteoarthritis will be near the top of the list of conditions that Unity Biotechnology plans to treat with senolytic drugs capable of selectively destroy senescent cells. These unwanted cells generate inflammation through the signaling molecules they create, and thus a role in osteoarthritis makes a lot of sense in hindsight.

Today's open access paper on the relationship between age and osteoarthritis focuses more on oxidative stress than on inflammation, however. Oxidative stress is the excessive generation of oxidative molecules by cells, which can cause damage or even cell death, but perhaps just as importantly it can alter cellular behavior in quite sweeping ways. Oxidative stress and inflammation often go hand in hand, and there is plenty of evidence to suggest that one is capable of causing the other, with the arrow of causation pointing in either direction. So one might take this paper as a different view of the same overall set of mechanisms, a different emphasis on investigation and intervention.

Nonetheless, if you read through the observations, it is clear that a sizable number of those thought most relevant to the development of osteoarthritis point towards the activities of senescent cells in one way or another. This perhaps even includes the oxidative stress given the lines that can be drawn between cellular senescence and mitochondrial dysfunction, and between inflammation and oxidative stress, though clearly the age-related cross-linking found in cartilage has its own independent and significantly detrimental effects. This isn't just senescent cells at work, even if it turns out to be mostly senescent cells at work. Fortunately the advent of senolytics will enable researchers to make inroads into disentangling these various causes and their consequences: removing one of the causes is the fastest and most effective way to determine the size of its contribution and its relationship with other mechanisms.

The Role of Aging in the Development of Osteoarthritis

Osteoarthritis (OA) is one of the most common causes of pain and disability in adults. There are a host of risk factors for the development of OA that include joint injury, obesity, genetic predisposition, and abnormal joint shape and alignment. However, the factor that has the greatest influence on the incidence and prevalence of OA is age. A major limitation in the management of patients with OA is the lack of any therapy that can slow the progression of the disease. The lack of any intervention that targets the disease process has resulted in a substantial increase in joint replacement surgery. Clearly, a safe, effective and less-expensive treatment that can alter the course of the disease will have a major impact on both quality of life and future health-care expenditures. The obvious billion dollar question is how do we slow or stop the progression of joint damage and improve symptoms in individuals with OA.

OA is a slowly progressive disease of synovial joints characterized pathologically by focal destruction of the articular cartilage, a hypertrophic response in neighboring bone that results in osteophyte formation and subchondral sclerosis, variable degrees of synovial inflammation, a thickening of the joint capsule, and damage to soft tissue structures including ligaments and, in the knee, the meniscus. The destruction and loss of the articular cartilage is central to the development of OA and most of the research to date on aging mechanisms relevant to OA has focused on changes in the cartilage. It is important to note that joint aging and OA are not one and the same but rather aging changes can make the development of OA more likely to occur. With normal aging the cartilage appears slightly brown due to an accumulation of advanced glycation end-products and is thinner than in young adults but is otherwise smooth and intact. The accumulation of advanced glycation end-products has been found to alter the biomechanical properties of cartilage making it more "brittle" and susceptible to degeneration. In contrast, in joints affected by OA there is marked destruction and loss of the cartilage accompanied by osteophytes and subchondral bone thickening.

The destruction and loss of the articular cartilage in OA is driven by an imbalance in the production and activity of pro-inflammatory and catabolic mediators. The imbalance in catabolic and anabolic signaling results in overproduction of matrix degrading enzymes including the matrix metalloproteinases (MMPs) and aggrecanases. MMP-13 is important because of its ability to degrade type II collagen, the major structural protein in cartilage which provides the tissue's tensile strength, whereas the aggrecanases are notable for their ability to degrade aggrecan, the large proteoglycan that is responsible for the resiliency of cartilage.

Aging processes that promote an imbalance in chondrocyte signaling resulting in increased production of MMPs and aggrecanases would be central to the development and progression of OA. A focus of our research efforts, and others in the field, has been on gaining a better understanding of the basic molecular mechanisms driving this imbalance in signaling. This could be due to cellular senescence and the development of what has been termed the senescence-associated secretory phenotype. The senescence-associated secretory phenotype is characterized by increased production of many of the same cytokines, chemokines, and MMPs found in OA cartilage, suggesting that OA chondrocytes assume a senescent phenotype. More studies are needed to define the underlying mechanisms of chondrocyte senescence and to determine if removal of senescent cells using compounds that have been called "senolytics" would slow the progression of OA and be disease and/or symptom modifying.

Hallmarks of aging have been proposed, such as cellular senescence and telomere attrition, that are believed to represent key mechanisms by which aging contributes to the development of age-related conditions. One of the hallmarks is mitochondrial dysfunction which can promote age-related disorders in part through increased levels of reactive oxygen species (ROS). Age-related mitochondrial dysfunction has been suggested as a contributing factor in the development of OA. To obtain in vivo support for the hypothesis that mitochondrial dysfunction promotes the development of OA through increased levels of ROS, we evaluated the severity of naturally occurring OA in transgenic mice engineered to express human catalase targeted to the mitochondria. These mice have been shown to have reduced markers of oxidative stress with aging, accompanied by a reduction in age-related pathology and increased lifespan. Compared to age-matched wild-type controls, we found that the 18- to 33-month-old male MCAT mice had a modest but significant reduction in the severity of OA changes in knee articular cartilage.

It is thought that elevated levels of ROS, found in oxidative stress conditions, could promote age-related conditions through the disruption of physiologic signaling. In a series of studies, we have shown that oxidative stress occurs with aging in articular cartilage and this promotes an imbalance in catabolic and anabolic signaling that could play a key role in the development of OA. IGF-1 and OP-1 are key cartilage growth factors and we showed a reduced response of human articular chondrocytes to IGF-1 or the combination of IGF-1 and OP-1, resulting in reduced matrix gene expression and matrix protein synthesis. The reduced response to these growth factors appears to be due to altered cell signaling mediated by oxidative stress.

In summary, there are likely multiple factors related to aging that promote the development of age-related conditions such as OA. A central feature of OA is the imbalance in catabolic and anabolic signaling in cartilage that results in progressive matrix destruction. Our studies are providing evidence that age-related oxidative stress plays a key role in this catabolic-anabolic imbalance. Studies on the molecular mechanism are revealing excessive oxidation of key anti-oxidant systems in chondrocytes. Oxidative inactivation of anti-oxidant systems allows for rising levels of intracellular ROS that cause disruption of physiologic signaling. The failure of simple anti-oxidants to impact aging and age-related disease may be related to their inability to specifically target this disrupted signaling. Future interventions that can restore proper redox signaling in aging chondrocytes hold promise for the treatment of OA.

Reprogramming of Fibroblasts as an Approach to Reduce Heart Fibrosis

There have been a few papers published in recent days covering efforts to reduce fibrosis in the aging heart, and here is another one. Fibrosis is the excessive creation of scar-like structures that disrupt tissue function, and is a consequence of the dysregulation in regenerative processes that occurs with age. There are no truly effective treatments for fibrosis presently available, but several lines of research are quite promising. Senolytic therapies to clear senescent cells in particular should reduce fibrosis, as the link between senescent cells and fibrosis seems clearly established at this time. The other potential approaches involve various ways to interfere with the mechanisms that generate the scarring of fibrosis, in this case by reprogramming the fibroblasts largely responsible for creating fibrotic structures.

During a heart attack, blood stops flowing into the heart; starved for oxygen, part of the heart muscle dies. The heart muscle does not regenerate; instead it replaces dead tissue with scars made of cells called fibroblasts that do not help the heart pump. The heart weakens; most people who had a severe heart attack will develop heart failure, which remains the leading cause of mortality from heart disease. A team of researchers has shown that administration of a cocktail made of transcription factors Gata4, Mef2c and Tbx5 (GMT) results in less scar tissue, or fibrosis, and up to a 50 percent increase in cardiac function in small animal models of the disease. This result was presumed to be mostly a consequence of the reprograming of heart fibroblasts into cardiomyocyte-like cells. Interestingly, the team noticed that reduced fibrosis and improved cardiac function far exceeded the extent of induced new cardiomyocyte-like cells.

"We and others had described that, in addition to inducing reprograming of fibroblasts into cardiomyocyte-like cells, the GMT cocktail also induced reduction of post-heart attack fibrosis. However, not much attention had been paid to the latter." The research team investigated in more detail how the GMT cocktail activated mechanisms that reduced fibrosis. They found the first evidence that, of the three components in the GMT cocktail, only Gata4 was able to reduce post-heart attack fibrosis and improve cardiac function in a rat model of heart attack. Further exploration of the molecular mechanism mediating this novel effect showed that administering Gata4 to rat fibroblasts in the lab resulted in reduced expression of Snail, the master gene of fibrosis. "Gata4 plays a complex role in heart regeneration: as part of the GMT cocktail, it contributes to the reprograming of fibroblasts into cardiomyocyte-like cells; we know it contributes to heart hypertrophy - the development of an enlarged heart - and now we discovered that it alone can decrease cardiac fibrosis. Others have reported that Gata4 also can suppress liver fibrosis. There is still a lot to be done before we can transfer these discoveries to the bedside, but they are important first steps."


GRK2 as a Target for the Treatment of Heart Fibrosis

Fibrosis is one of the characteristics of old tissue, a disarraying of the normal processes of regeneration and tissue maintenance that leads to the formation of scar-like structures and consequent loss of tissue function. This is especially notable in the heart, in the kidneys, and in some lung conditions. Little progress was made towards effective therapies until it was determined that senescent cells in old tissue are an important cause of fibrosis; the various therapies under development that target and remove these cells should prove useful in this regard. This isn't the only line of research that might prove viable enough to make a meaningful difference, however. Here, researchers report on continued efforts to sabotage fibrosis via the GRK2 protein and its interactions.

Researchers report encouraging preclinical results as they pursue elusive therapeutic strategies to repair scarred and poorly functioning heart tissues after cardiac injury. They inhibited a protein that helps regulate the heart's response to adrenaline. This alleviated the disease processes in mouse models of human heart failure, and in cardiac cells isolated from heart failure patients. The experimental approach focuses on the role of the proteins Gβγ and GRK2, which are involved in a signaling pathway activated by adrenaline stimulation. The adrenergic system plays a fundamental role in maintaining normal heart function. Data shows that chronic over stimulation of the system (which happens after a heart attack) prompts hypertrophy - a thickening and enlargement of the heart muscle. It also causes fibrosis, the formation of scar tissue.

In a mouse model that closely simulates the disease progression in humans after a heart attack, the researchers blocked Gβγ-GRK2 molecular signaling with an experimental small molecular inhibitor called gallein. When treatment was started one week after the initial cardiac injury, it preserved heart function and reduced tissue scarring and enlargement - essentially rescuing the animals from heart failure. The authors also reported a similar level of protection in a new genetically altered mouse model in which GRK2 is removed from a specific cell type in the heart - the cardiac fibroblast. "Regrettably, there are essentially no clinical interventions that effectively target these tissue-damaging cardiac fibroblasts. This work may provide evidence that shifts the way we think about treating heart failure."

Researchers first tested the compound gallein by administering it one week following cardiac injury in control mice with unaltered expression of GRK2. Four weeks after the initial cardiac injury, control mice showed signs of significant fibrosis and heart dysfunction, although targeted Gβγ-GRK2 inhibition with gallein offered the animals substantial cardiac functional protection. This included preservation of the heart muscle's contractile abilities and a reduction of fibrosis within the cardiac tissue. In a second group of mice, the team genetically removed the GRK2 protein shortly after cardiac injury from cardiomyocytes, the contractile/functional cells of the heart. In mice that had GRK2 specifically removed from their cardiomyocytes post-injury, gallein treatment demonstrated significant protection of heart function in the animals. This suggests a potential protective role for the drug beyond cardiomyocyte cells.

In a third group of mice, GRK2 expression was eliminated post injury from just heart fibroblast cells. These animals maintained nearly normal heart function and showed significant improvements in ejection fraction (how forcefully the heart muscle pumps blood) with no further cardiac protection provided by gallein treatment. Researchers attribute the benefits of Gβγ-GRK2 inhibition to a decrease in the pathologic activation of cardiac fibroblasts, as well as a subsequent reduction in fibrosis in the injured cardiac tissue. Taken together, these findings suggest that the improvements observed in the heart's contractile performance after injury may be the result of an overall reduced fibrotic burden.


A Cell Therapy Reduces the Number of Senescent Cells in Aged Rat Hearts, and Reverses Numerous Measures of Aging

The research results noted here today are most interesting, as the scientists involved report success in turning back a number of measures of cardiovascular and general aging in old rats via delivery of cells derived from young heart tissue. This work touches on a whole range of themes from recent years: cell therapies involving transplants from young to old individuals; that cell therapies might produce the bulk of their beneficial effects through cell signaling; the degree to which vesicles are the important channel for that cell signaling; the role of cellular senescence in the processes of tissue aging, such as rising levels of fibrosis; and to round out the selection, considerations of telomere dynamics and telomerase activity. It is a fairly impressive collection of important topics for just the one study.

To me the the point that stands out is that senescent cells were reduced in number following treatment. I would like to know whether this happens because signaling from the transplanted cells pushes these lingering senescent cells across the line into self-destruction via apoptosis, or whether it spurs the immune system to destroy them, though I imagine I'll be waiting a few years to find out. Most of the metrics mentioned in the paper could be explained by reduction in senescent cell count, as via the senescence-associated secretory phenotype (SASP), these unwanted cells are directly responsible for chronic inflammation, fibrosis, disruption of regeneration, and possibly cardiac hypertrophy. The evidence for those consequences of cellular senescence has amassed in numerous papers over the past few years. We should also expect senescent cells to contribute meaningfully to many or most of the other aspects of aging in similar ways.

We might speculate on the size of the senolytic contribution in this study versus that of increased telomerase and consequent changes in average telomere length. While there are examples of increased telomerase producing benefits to health and longevity in rodent studies, it has to be noted that rodent telomere dynamics are very different from those of humans. For one, rodents express telomerase in somatic cells, whereas humans do not. So it isn't at all clear what the telomere and telomerase observations here mean when it comes to predicting outcomes in humans. It is possible to suggest that additional telomerase and telomere lengthening in stem cells may have analogous effects, as the situation in rodents and humans for stem cell telomere dynamics is less radically different. But for an observation of increased telomerase in somatic cells? Hard to say.

That said, this is a very promising study that opens many doors for further exploration. What in the vesicles is acting as a senolytic therapy to remove senescent cells? Might this behavior be found in other cell types, and can it be generalized, identified, and recreated to order via cell programming techniques? To what degree are the results shown in this study due to reduced burden of cellular senescence versus consequences of increased telomerase versus other possible mechanisms? Is there a useful shortcut in all of this to human cell therapies that will have more of an effect on the underpinnings of aging than those developed to date? These and other, similar questions spring to mind immediately.

Stem Cells From Young Hearts Could Rejuvenate Old Hearts

In the study, investigators injected cardiosphere-derived cells, a specific type of stem cell known as CDCs, from newborn laboratory rats into the hearts of rats with an average age of 22 months, which is considered aged. Other laboratory rats from the same age group were assigned to receive placebo treatment, saline injections instead of stem cells. Both groups of aged rats were compared to a group of young rats with an average age of 4 months. Baseline heart function was measured in all rats, using echocardiograms, treadmill stress tests, and blood analysis. The older rats underwent an additional round of testing one month after receiving cardiosphere-derived cells that came from young rats.

"The way the cells work to reverse aging is fascinating. They secrete tiny vesicles that are chock-full of signaling molecules such as RNA and proteins. The vesicles from young cells appear to contain all the needed instructions to turn back the clock." Results of those tests show lab rats that received the cardiosphere-derived cells experienced the following: improved heart function; demonstrated longer heart cell telomeres; improved their exercise capacity by an average of approximately 20 percent; and regrew hair faster than rats that didn't receive the cells. "This study didn't measure whether receiving the cardiosphere-derived cells extended lifespans, so we have a lot more work to do. We have much to study, including whether CDCs need to come from a young donor to have the same rejuvenating effects and whether the extracellular vesicles are able to reproduce all the rejuvenating effects we detect with CDCs."

Cardiac and systemic rejuvenation after cardiosphere-derived cell therapy in senescent rats

Cardiosphere-derived cell (CDC) therapy has exhibited several favourable effects on heart structure and function in humans and in preclinical models; however, the effects of CDCs on aging have not been evaluated. We compared intra-cardiac injections of neonatal rat CDCs to a control of phosphate-buffered saline, PBS, in 21.8 ± 1.6 month-old rats (mean ± standard deviation; n = 23 total). Ten rats of 4.1 ± 1.5 months of age comprised a young reference group. Blood, echocardiographic, haemodynamic and treadmill stress tests were performed at baseline in all animals, and 1 month after treatment in old animals. Histology and the transcriptome were assessed after terminal phenotyping. For in vitro studies, human heart progenitor cells from older donors, or cardiomyocytes from aged rats were exposed to human CDCs or exosomes secreted by CDCs from paediatric donors.

Transcriptomic analysis revealed that CDCs, but not PBS, recapitulated a youthful pattern of gene expression in the hearts of old animals (85.5% of genes differentially expressed). Telomeres in heart cells were longer in CDC-transplanted animals. Cardiosphere-derived cells attenuated hypertrophy; histology confirmed decreases in cardiomyocyte area and myocardial fibrosis. Cardiosphere-derived cell injection improved diastolic dysfunction compared with baseline, and lowered serum brain natriuretic peptide. In CDC-transplanted old rats, exercise capacity increased ∼20%, body weight decreased ∼30% less, and hair regrowth after shaving was more robust. Serum biomarkers of inflammation (IL-10, IL-1b, and IL-6) improved in the CDC group. In summary, young CDCs secrete exosomes which increase telomerase activity, elongate telomere length, and reduce the number of senescent human heart cells in culture.

Is the Mitochondrial Permeability Transition Pore at the Center of Mitochondrial Contributions to Aging?

Researchers here outline a model of mitochondrial dysfunction as a contributing cause of aging that centers around mitochondrial permeability transition pores, molecular structures that govern the permeability of the inner mitochondrial membrane. These pores are known to be associated with the mitochondrial stress and functional failure that is observed in the biochemistry of numerous age-related diseases, but the degree to which this is a consequence versus a cause of damage is one of many open questions in the cellular biology of aging. The more usual focus of the mitochondrial contribution to aging is damage to mitochondrial DNA, and consequent operational failure due to loss of specific proteins needed for normal mitochondrial function. This is the basis for the SENS rejuvenation research approach of copying mitochondrial genes into the cell nucleus to provide a backup source of these proteins.

Oxidative stress in animals is strongly correlated with aging and lifespan, as predicted by the free radical theory of aging (FRTA). Because most reactive oxygen species (ROS) are generated in the mitochondria (mROS), in close proximity to mitochondrial DNA (mtDNA) and the mitochondrial oxidative phosphorylation system, it was suggested that oxidative damage to mtDNA, mitochondrial proteins, and phospholipids is the direct cause of aging and determines lifespan. This more specific version of FRTA was named the mitochondrial free radical theory of aging. The evidence supporting mFRTA is extensive.

The mitochondrial permeability transition pore (mPTP) is an inner membrane protein complex that can be induced to form a nonselective channel. The channel exhibits several conducting states that can open for short (milliseconds) or long (seconds) periods, and with different permeabilities. Full opening of the mPTP results in increased production of mROS and release of most associated metabolites. As a result, the mitochondrial membrane potential collapses, oxidative phosphorylation and mitochondrial metabolism are inhibited, the matrix swells, and on prolonged opening the outer membrane ruptures, releasing intermembrane space proteins. Moreover, the release to the cytosol of ROS and metabolites disrupts cellular homeostasis and increases oxidative damage. Prolonged pore opening in a large number of mitochondria in the cell can lead to cell death by necrosis or similar pathways.

Frequent and extended opening of the mPTP, with its associated bursts of mROS, can overwhelm the cell's antioxidant systems resulting in extensive DNA damage. A more moderate ROS production by mitochondria may not lead to strong pro-apoptotic signals but is sufficient to trigger various mechanisms that adjust cellular processes and protect the mitochondria and the cell from damage. This level of ROS formation is mostly contained by antioxidant systems. When their capacity is exceeded, the increased oxidative stress activates the mPTP. While short, infrequent opening of the mPTP also triggers protective pathways, increasing the frequency and duration of the mPTP is associated with more persistent oxidative damage that may result in aging and even cell death.

Because it is difficult to untangle the protective effects of mROS from its deleterious effects, the concept of FRTA has not been widely accepted. Instead, a consensus is emerging in which the balance between mROS-induced protective pathways and cell damage-induced apoptotic pathways is somehow integrated in the mitochondria to determine the progression of aging and ultimately cell death. Here, we propose that these contrasting signals are integrated at the level of the mPTP, which largely determines the rate of aging and ultimately lifespan by the frequency and duration of pore openings.

The hypothesis that mPTP is the driver of aging can be considered a refinement of mFRTA as it is proposed that much of the oxidative damage to the mitochondria itself results from the activation of mPTP and that most of the effects of 'mitochondrial dysfunction' and mROS on aging and lifespan are mediated through activation of the mPTP. By controlling both the depletion of cellular NAD+ and the induction of a strong DNA damage response, mPTP can drive aging and death of postmitotic cells as well as senescence in mitotic cells. Moreover, it is likely that mPTP opening also mediates mROS-driven inflammation, because the formation of the NPLR3 inflammasome appears to depend on opening of the mPTP, and chronic activation of the mPTP (by deletion of MICU1) was found to extend the pro-inflammatory response in response to injury.

The fact lifespan can be extended experimentally in several animal models of aging, and the findings that in many cases lifespan extension appears to depend on mROS signaling are often cited as the strongest evidence against mFRTA. Evidently, in these cases, mROS initiate the mitochondria protection pathways at an early age and this leads to lifespan extension. The mitochondrial protection pathways invariably lead to inhibition of the mPTP, whether indirectly by inhibition of mROS production, increased antioxidant protection, increased mitophagy, and increased mitochondrial biogenesis, or by direct inhibition of mPTP activation. In a study of a very large number of C. elegans lifespan modulations by mutations and environmental manipulations, it was shown that lifespan correlates negatively with the frequency of 'mitoflashes' at an early adult age. If one accepts the interpretation that 'mitoflashes' signal the opening of the mPTP, it could be argued that in all these cases lifespan extension is the result of inhibition of mPTP opening in early adulthood. Metformin, the first drug approved for clinical trials for retarding the progress of human aging, was shown to inhibit the mPTP. Thus, it is likely that in most, if not all, manipulations that extend animal lifespan, the mPTP is inhibited, directly or indirectly.

In summary, we suggest that the mPTP itself is the elusive site of integration of the contrasting pro- and antiapoptotic signals that determine the rate of progression to aging. While many processes upstream of the mPTP (e.g., oxidative phosphorylation, electron transport, mROS production, mitochondrial antioxidant defense, mitophagy, mitochondrial biogenesis) are also affected by the various protection mechanisms, it is likely that these upstream processes affect aging largely through their effects on mPTP activation. There is still much to be learned about the composition and structure of the mPTP, the mechanisms that control mPTP opening, the various activation states of the mPTP, the extent and types of ions and metabolites that are released, and how the progression of aging affects these processes. The progression of aging to death does not follow a uniformly shaped curve in all animals. An animal's lifespan can be determined by the failure of one particular critical organ, by either postmitotic or mitotic cells, and differences between the control of the mPTP in different organs, and different types of cells, may account for some of the differences between species. Further studies of the control of mPTP in aging can open the door to a much better understanding of the determinants of longevity.


Senescent T Cells, Immunosenescence, and T Cell Exhaustion are all Distinct but to Some Degree Overlapping Phenomena

Immunosenescence is a high-level descriptive term for one collection of symptoms that manifest in the aging immune system, largely revolving around a loss of capacity: an inability to respond effectively to pathogens and to clear out damaged and dangerous cells. Cellular senescence on the other hand is a low-level descriptive term for a harmful cell state that appears in increasing numbers with advancing age, disrupting tissue function and contributing to age-related diseases. The evidence to date strongly suggests that senescence as a cellular phenomenon extends to the T cells of the adaptive immune system in later life, though it is not yet clear just how similar this is to the manifestation of senescence as it is observed in other cell types, or the degree to which it contributes to immunosenescence.

To further muddy the waters, T cell senescence is not the same as T cell exhaustion, a separate form of immune cell dysfunction that is also associated with age and immunosenescence. Assigning names in biochemistry is a process of drawing a ragged circle around a collection of measures and markers, and perhaps later, once the systems involved are mapped and understood to a much greater degree, some reconciliation and renaming will take place where the accumulated nomenclature becomes obsolete or overlaps in a confusing manner. That point has yet to be reached here.

The immune system is made up of many different immune cell types, each with its own unique functions, to collectively protect the host against foreign pathogens. T cells comprise around 7-24% of the immune cells and around ~70% of the lymphocytes in human blood. The ability of T cells to proliferate upon antigen stimulation is crucial as it dramatically increases the number of antigen-specific T cells to aid in resolving the infection, otherwise known as clonal expansion. After the resolution of the infection, these T cells undergo apoptosis during the contraction phase to return to the steady state. However, as T cells replicate multiple times due to repeated stimulation with pathogens during a host's lifetime, they further differentiate, lose their proliferation capacity and may reach the stage of replicative senescence.

The inability of T cells to proliferate is partly due to the erosion of telomeres and the loss of telomerase activity, a phenomenon is analogous to the Hayflick Limit first characterized in fibroblasts. Besides having an impaired proliferative capacity and shorter telomere length, senescent fibroblasts also adopt a pro-inflammatory profile, whereby they could secrete pro-inflammatory cytokines into the environment and cause tissue damage by chronic inflammation. However, these features of senescence are only established in other cell types, and classical T cells may shares similar features but the signals and pathways leading to those functional hallmarks may be different. Whether cellular senescence shares common pathways across all immune cells and all mammalian cells still needs to be demonstrated.

It is not surprising that investigators are often confused with the terms senescence and exhaustion of T cells. Senescence and exhausted T cells do have some similarity in certain aspects of functionality but they are not entirely the same. Therefore, it is important to note the differences between senescence and exhaustion of T cells, as this will allow accurate interpretation of results and propose the right therapeutic approach to be used. First, the markers expressed by senescent T cells are markers such as CD57 and KLRG-1, which indicates replicative senescent. On the other hand, the markers associated with exhaustion of T cells are programmed cell death 1 (PD-1), lymphocyte activation gene 3 (LAG-3), T cell immunoglobulin mucin 3 (TIM-3) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4).

Second, senescent T cells adopt a pro-inflammatory profile and are able to secrete high levels of pro-inflammatory cytokines with stimulation which is similar to the senescence associated secreting phenotype (SASP) observed in other senescent cell types. The SASP concept has been established in non-immune cells but it remains to be proven in T cells. However, as SASP cells are unable to proliferate but can produce a higher range of pro-inflammatory molecules, it is likely that senescent T cells exhibit some aspects of SASP. Exhausted T cells are unable to both proliferate and to secrete cytokine upon stimulation suggesting again that the two definitions refer to different cellular status.

Third, senescent T cells are more prevalent in the highly-differentiated phenotypes (effector memory/terminal effector) and resistant to apoptosis. Exhausted T cells on the other hand, are usually central memory/effector memory T cells that have undergone repetitive or chronic stimulation. They are programmed to undergo apoptosis as PD-1 pathway seems to strongly associate with survival. Lastly, replicative senescent seems to be irreversible whereas exhaustion is reversible. Studies have shown that blockade of PD-1 ligation is able to recover the function of cytokine secretion in T cells. "Reversing exhaustion" has been very successful in human clinical trials, raising the 5-year survival rate of different type of cancer patients in advanced cancer stages.

Senescent T cells were recently shown to regain function by inhibiting the p38 mitogen-activated protein kinase (MAPK) pathway. Restoring function of senescent T cells is very relevant in the context of human aging while restoring the function of exhausted T cells is more relevant in a pathological context (e.g., cancer immunotherapy, infectious diseases). Having clarified the differences between senescent and exhausted T cells, the markers associated with each phenotype could be co-expressed on the surface of the T cells, which means they could be both senescent and exhausted. It is not clear, however, whether senescent T cells are more susceptible to exhaustion and vice-versa.


A Perhaps Surprisingly Large Degree of Age-Related Frailty is Self-Inflicted

No-one can choose not to age, at least not until reliable, low-cost rejuvenation therapies are developed, but some aspects of aging can be accelerated through simple neglect - and one can therefore choose to avoid that burden. Frailty is one of these aspects: a condition of weakness and lack of resilience found in many older people. Losses of muscle mass and bone strength, immune system and organ function all play their part. There are various formal definitions of frailty as a medical condition, but there is no bright dividing line here: it is a continuum of decline. Frailty is an end state of aging, and everyone will get there eventually unless claimed by one of the common fatal age-related conditions first. Nonetheless, it is certainly possible to get there faster rather than more slowly, by making poor choices in health and lifestyle. The research materials linked below argue that the majority of people are not aware of the degree to which they are harming themselves, and that efforts should be taken to correct this state of affairs.

In our technological society of cheap calories, easy transportation, and replacements for physical labor, most people eat too much and exercise too little. That becomes ever more pronounced over the years, as older individuals tend to become wealthier and thus more able to enjoy all of these comforts. This has a cost when it comes to health, and there is a large body of research that seeks to put numbers to that cost, both for the average individual and for the population as a whole. Avoidable damage done to health over the long term is often referred to as secondary aging. It includes, for example, the consequences of chronic inflammation and other metabolic disruption produced by excess visceral fat, as well as accelerated loss of muscle resulting from lack of exercise. Near everyone in later life fails to exercise sufficiently, as demonstrated by study after study showing improvement in the muscle and health of even very old people following modest resistance exercise programs.

Ultimately, forms of applied biotechnology will eliminate the need for exercise and calorie counting, but this lies at least decades in the future, well past the immediate focus on first generation rejuvenation therapies that each only address one narrow fraction of the causes of aging. I suspect that the development of the full portfolio of therapies needed to turn back aging will itself stretch over decades, from the easiest such as senolytics to the hardest such as comprehensive stem cell replacement. There is still a role for taking care of your own health even in the midst of a revolution in medical biotechnology, because the trajectory of secondary aging you set for yourself today will be a sizable determinant of the degree to which you can benefit tomorrow from the first incremental advances in treating the causes of aging.

Preparing for longevity -- we don't need to become frail as we age

"Societies are not aware of frailty as an avoidable health problem and most people usually resign themselves to this condition. Fortunately, by proper lifestyle and adequate physical, mental, and social activities, one may prevent or delay the frailty state." Frailty encompasses a range of symptoms that many people assume are just an inescapable part of aging. These include fatigue, muscle weakness, slower movements, and unintentional weight loss. Frailty also manifests as psychological and cognitive symptoms such as isolation, depression, and trouble thinking as quickly and clearly as patients could in their younger years. These symptoms decrease patients' self-sufficiency and frail patients are more likely to suffer falls, disability, infections, and hospitalization, all of which can contribute to an earlier death.

There is ample evidence that the prevalence and impact of frailty can be reduced, at least in part, with a few straightforward measures. Unsurprisingly, age-appropriate exercise has been shown to be one of the most effective interventions for helping the elderly stay fit. Careful monitoring of body weight and diet are also key to ensuring that older patients are not suffering from malnutrition, which often contributes to frailty. "Social campaigns should inform societies about age related frailty and suggest proper lifestyles to avoid or delay these conditions. People should realize that they may change their unfavorable trajectories to senility and this change in mentality is critical to preparing communities for greater longevity."

Is It Time to Begin a Public Campaign Concerning Frailty and Pre-frailty?

Frailty is a geriatric syndrome caused by a multisystem decrease in reserve capability and is associated with a high risk for various adverse outcomes. Frailty is not synonymous with either comorbidity or disability, but comorbidity is a risk factor for frailty, and disability is an outcome of frailty. Pre-frailty is a condition predisposing and directly preceding frailty. The frailty state is associated with a variety of adverse consequences, such as falls, cognitive decline, infections, hospitalization, disability, institutionalization, and death. Frail patients present much worse prognoses than non-frail patients, particularly in cardiovascular diseases. Moreover, frailty impairs the effects of invasive treatments in these disorders, e.g., percutaneous coronary interventions, transcatheter aortic valve implantations or coronary artery bypass grafting. Frailty also imposes a significant financial burden on health systems, particularly because frailty appears to have an incremental effect on ambulatory health expenditures.

Awareness of these facts may afford us an opportunity to develop cost-effective care for this group of people, resulting in improvement in long-term care and its outcomes. However, despite numerous studies addressing this condition in recent years, frailty as an entity is not commonly recognized in the general population or even by some medical societies, and there are no consistent preventative and therapeutic strategies dedicated to this disorder. Because population aging is associated with a higher prevalence of frailty and pre-frailty, it is necessary to familiarize societies with these states. Moreover, if we want to improve the quality of life of elderly persons and reduce expenses for their care in the future, we should take preventative measures against frailty now. Therefore, it is time to begin treating frailty like other population-affecting diseases such as obesity, diabetes or hypertension. Appropriate prospective studies are needed to define which preventative lifestyle interventions should be implemented to ensure good physical and mental conditions in senility. Social campaigns could draw societies' attention to proper life habits that may be effective to avoid not only diabetes and cardiovascular diseases but also age-related frailty.

Clarifying Circadian Rhythm in Stem Cell Aging

Circadian rhythms, repeated 24-hour cycles of change, run in many parts of our biochemistry. Like most aspects of metabolism and its regulation, circadian rhythms become disrupted in later life. Numerous research groups have put in time trying to map this disruption, attempting to find its place in the chains of cause and effect that take place in aging and age-related disease. The research noted here is an example of incremental progress in this part of the field, a clarification of the role of circadian rhythm in stem cell aging. The activity of stem cells declines with advancing age, and thus tissue maintenance and function declines with it. The research community is seeking points at which to interfere safely to slow or reverse this decline, though to my eyes much of this work takes place too far down the lengthy chain of cause and effect that leads from fundamental molecular damage to age-related disease. Addressing root causes should be far more effective than attempting to clear up consequences.

It is widely believed that, with the passage of time, stem cells cease to differentiate between day and night cycles, in other words they lose their circadian rhythm, and that this loss promotes ageing. However, this has been found not to be the case. Two recent studies reject this hypothesis. During ageing, stem cells continue to show rhythmic activity but reprogram their circadian functions. "Aged stem cells conserve circadian rhythm but now perform another set of functions to tackle the problems that arise with age. The problem is that as they age, stem cells lose the rhythmic functions necessary for tissue protection and maintenance, which become replaced by functions aimed at coping with stress. Loss of the previous circadian functions of stem cells during natural ageing contributes in some way to greater damage and greater ageing".

In both studies, researchers compared stem cells from young mice (three months old) with those of aged mice (between 18 and 22 months old) in three kinds of tissue, namely skin, muscle and liver, every four hours over one day. It is known that a low-calorie diet delays the signs of ageing in primates and mice. In another set of experiments, researchers gave mice a low-calorie diet for six months and compared them with counterparts on a normal diet. The animals on the low-calorie diet conserved most of the rhythmic functions of their youth. According to the researchers, this would explain why a calorie restriction diet slows down ageing. What is not clear is whether low-calorie diets would keep ageing at bay in humans. In this regard, it is important to further examine why metabolism has such a dominant effect on the stem cell ageing process and, once the link that promotes or delays ageing has been identified, to develop treatments that can regulate this link.

"Although ageing always involves circadian reprogramming, an interesting aspect of our results is that such reprogramming is specific and distinct for each type of tissue studied. This observation implies that although the entire organism is ageing, each tissue goes through this process in a different way. So to address the slowing down of ageing, it will be necessary to study each tissue separately. Keeping the rhythm of stem cells "young" is important because in the end these cells serve to renew and preserve very pronounced day-night cycles in tissues."


Dysfunctional Golgi Apparatus Implicated in Some Forms of Neurodegeneration

Researchers have shown that dysfunction in Golgi apparatus organelles in brain cells is important in some forms of neurodegenerative disease, and identified a controlling protein that might be used in order to partially reverse this dysfunction. The Golgi apparatus is involved in the later stages of production and deployment of protein machinery in the cell; it packages up proteins for dispatch to their destination inside the cell, or for secretion outside the cell. Some past research has suggested relevance for Golgi apparatus failure in Alzheimer's disease, and there are indications that Golgi function might be one of the factors determining differences in species longevity.

Researchers have identified the early neuropathic mechanism of polyglutamine brain disease, one of the representative degenerative brain diseases, and suggested a way to restore it. It is expected to accelerate the development of the early neuropathy treatment for a variety of degenerative brain diseases. The research teams have verified for the first time in the world that dendritic-specific Golgi, one of the cellular organelles in neurons, plays a key role in early neuropathy of degenerative brain disease.

In a model of degenerative brain diseases such as Huntington's chorea and spinal cord cerebellar degeneration that are caused by polyglutamine toxic protein, the research teams identified that deformation or abnormality of dendritic-specific Golgi, which plays a key role in supplying the cell membrane of brain cells, is the major cause of degenerative brain disease as it leads morphological transformation of neuronal cells.

In these morphologically modified brain cells, the study has demonstrated that the early neuropathy of diseased brain cells can be restored by inducing overexpression of the CrebA gene, the newly discovered key factor in pathology. In addition, by identifying the transcription factors involved in the early neuropathy caused by toxic proteins such as CrebA and high-level factor CREB-binding protein, the researchers have suggested that they could be new subjects to develop therapeutic agents for degenerative brain diseases.


Towards Effective Sabotage of the Bacteria that Cause Tooth Decay

The research community has for some years now seemed on the verge of making real progress in the elimination of tooth decay and periodontal disease. That final leap from understanding and promising research to earnest clinical development always takes longer than we'd like it to, however. The most pressing and widespread dental issues are largely bacterial in origin, but not quite as straightforward as simply identifying one unwanted type of microbe and getting rid of it. This is a story of interactions between the behavior of different species, and the need to eliminate harmful behavior without disrupting the activities of the many beneficial bacterial species found in the mouth. The work needed to draw closer to practical treatments has developed across the course of this decade.

We should care about the decay of the mouth for the same reason we should care about the decay of the rest of the body. Every piece of our physiology is useful in some way. Further, everything is connected, and the harms that bacteria cause to gums in particular results in inflammation that spreads into other tissues. There is a strong association between the presence of forms of oral bacteria known to be problematic and overall mortality rates in later life. Given what we know of the role of inflammation in aging, this should not be surprising: it accelerates the development and progression of all of the common age-related diseases.

As the research noted here illustrates, the mouth is a proving ground for a range of approaches to the targeted sabotage of bacteria: efforts to remove specific bad behavior while changing as little else as possible. This strategy is almost forced on the medical community by necessity. The mouth is about as far from a sterile environment as it is possible to get, one in which even sophisticated attempts to eliminate bacteria for the long term usually prove futile. It is also home to many useful bacterial species whose removal will only cause issues, even if it was practical to keep them out for longer than a few days or weeks. The sort of heavy-handed antibacterial strategies that work so well for infections elsewhere in the body, or to eliminate bacterial strains that are only rarely encountered, and will not immediately replenished from the environment, are not useful here. Success in the development of more targeted approaches to oral bacteria may well find use elsewhere, however.

Small molecule inhibitor prevents or impedes tooth cavities in a preclinical model

Researchers have created a small molecule that prevents or impedes tooth cavities in a preclinical model. The inhibitor blocks the function of a key virulence enzyme in an oral bacterium, a molecular sabotage that is akin to throwing a monkey wrench into machinery to jam the gears. In the presence of the molecule, Streptococcus mutans - the prime bacterial cause of the tooth decay called dental caries - is unable to make the protective and sticky biofilm that allows it to glue to the tooth surface, where it eats away tooth enamel by producing lactic acid. This selective inhibition of the sticky biofilm appears to act specifically against S. mutans, and the inhibitor drastically reduced dental caries in rats fed a caries-promoting diet. "Our compound is drug-like, non-bactericidal and easy to synthesize, and it exhibits very potent efficacy in vivo. It is an excellent candidate that can be developed into therapeutic drugs that prevent and treat dental caries."

The glucan biofilm is made by three S. mutans glucosyltransferase, or Gtf, enzymes. The crystal structure of the GtfC glucosyltransferase is known, and the researchers used that structure to screen - via computer simulations - 500,000 drug-like compounds for binding at the enzyme's active site. Ninety compounds with diverse scaffolds showing promise in the computer screening were tested for their ability to block biofilm formation by S. mutans in culture. Seven showed potent inhibition and one, #G43, was tested more extensively. #G43 inhibited the activity of enzymes GtfB and GtfC. #G43 did not inhibit the expression of the gtfC gene, and it did not affect growth or viability of S. mutans and several other oral bacteria tested. Also, #G43 did not inhibit biofilm production by several other oral streptococcal species. In the rat-model of dental caries, animals on a low-sucrose diet were infected with S. mutans and their teeth were treated topically with #G43 twice a day for four weeks. The #G43 treatment caused very significant reductions in enamel and dentinal caries.

Structure-Based Discovery of Small Molecule Inhibitors of Cariogenic Virulence

Dental caries is a multifactorial disease of bacterial origin, which is characterized by the localized destruction of dental hard tissues. Though the oral cavity harbors over 700 different bacterial species, Streptococcus mutans initiates the cariogenic process and remains as the key etiological agent. Using key matrix producing enzymes, glucosyltransferases (Gtfs), S. mutans produces sticky glucosyl glucan polymers, which facilitate the attachment of the bacteria to the tooth surface. The glucans is a major component of the biofilm matrix that shields the microbial community from host defenses. Furthermore, copious amounts of lactic acid are produced as a byproduct of bacterial consumption of dietary sugars within the mature biofilm community, which ultimately leads to demineralization of the tooth surface, ensuing cariogenesis.

Selectively targeting cariogenic pathogens such as S. mutans has been explored previously, however it was found that the antimicrobial peptide also alters the overall microbiota. Our increasing understanding of bacterial virulence mechanisms provides new opportunities to target and interfere with crucial virulence factors such as Gtfs. This approach has the added advantages of not only being selective, but may also help to preserve the natural microbial flora of the mouth, which may avoid to exert the strong pressure to promote the development of antibiotic resistance, overcoming a major public health issue in the antibiotic era. It is well established that glucans produced by S. mutans Gtfs contribute significantly to the cariogenicity of dental biofilms. Therefore, the inhibition of the Gtf activity and the consequential glucan synthesis would impair the S. mutans virulence, which could offer an alternative strategy to prevent and treat biofilm-related diseases.

S. mutans harbors three Gtfs: GtfB, GtfC, and GtfD. Previous studies have demonstrated that glucans produced by GtfB and GtfC are essential for the assembly of the S. mutans biofilms. We conducted an in silico screening of 500,000 drug-like small molecule compounds targeting GtfC and identified top scored scaffolds for in vitro biofilm assays. Seven potent biofilm inhibitors emerged from this study, the lead compound #G43 was further characterized and shown to have anti-biofilm activity through the binding to GtfBC and the inhibition of the activity of GtfBC. The lead compound drastically reduced bacterial virulence in a rat model of dental caries.

Reaction Time Variability as a Marker of Aging

There are many easily measured biomarkers that correlate to various degrees with mortality risk and aging, such as grip strength, heart rate variability, as so forth. Given enough of them, it may be possible to build a much more accurate biomarker of aging through a weighted combination algorithm, but this has yet to be accomplished well enough to compete with the DNA methylation approach to measuring biological age. It is important to establish some useful form of biomarker of aging, however it is accomplished, as this can then be used to assess potential rejuvenation therapies far more cost-effectively than any of the other alternative options, such as running lengthy life span studies. Lack of a quick, cost-effective method of rating the outcome such therapies in both animal and human studies is holding back the field.

In addition to average performance level, there is an increasing focus in ageing research on intraindividual variability or inconsistency in cognitive performance. Such variability in performance is often measured by the trial-to-trial within-person variation in reaction times (RT) on a single cognitive task and is known as intraindividual reaction time variability (IIVRT). IIVRT has received considerable attention as a useful indicator of neurobiological disturbance. Consistent with this, several studies indicate that IIVRT is greater in older age and in a variety of neuropathological conditions of old age. Associations have been found with measures of brain integrity, including white matter hyperintensities, brain connectivity, and dopaminergic neuromodulation.

Our present interest is whether this measure can predict mortality in old age. It is possible that neurobiogical changes that are related to eventual mortality are captured by variability measures and are present many years in advance. A few studies have reported that increased variability predicts mortality up to 19 years before eventual death in older populations but it is unknown whether this association is independent of general age-related cognitive decline, an established risk factor for mortality. Moreover, the potential influence of incipient dementia on this relationship has not been addressed adequately in previous studies.

Hence, IIVRT warrants investigation as a specific predictor of impending death in older age independently of global cognitive level and other mortality risk factors. Therefore, the aim of this study was to investigate the association of IIVRT with mortality over 8 years in a large, well-characterised population-based cohort of older adults aged 70 years and over. In this large community-based old age cohort, greater variability in RT performance but not slower mean RT predicted all-cause mortality while adjusting for conventional mortality risk factors of age, sex, cardiovascular risk and APOE ɛ4 status and important potential confounders. Our findings broadly support and extend the small extant literature by providing further support for a strong association between IIVRT and all-cause mortality. The findings supports the view of IIVRT as a behavioural marker of neurobiological integrity.


Evidence for Cellular Senescence to be Involved in Cardiac Hypertrophy

In this open access paper, evidence is presented for senescent cells to be involved in the development of age-related cardiac hypertrophy, detrimental changes in the structure of the heart. The results here are somewhat more speculative than much of the recent evidence for cellular senescence to contribute to specific age-related conditions, most of which is direct and robust. Firstly the authors are arguing for senescence to be a relevant mechanism in a cell population that largely doesn't replicate, and therefore will not be generating large numbers of transient senescent cells as somatic cells hit the Hayflick limit. Fewer transient senescent cells means fewer senescent cells that fail to self-destruct and linger to cause issues. Another objection is the animal model used, which did not involve aged individuals, and so there is always the possibility that the type of damage and change in heart tissue caused here is not all that relevant to aging. Nonetheless, the results seem interesting, and there is always the point that fibrosis - a major feature of heart aging - is now well connected to cellular senescence in other tissues.

Pathological cardiac hypertrophy is the cellular response to biomechanical or neurohumoral stimuli. The defining features of hypertrophy are increased cardiomyocyte size, enhanced protein synthesis and reinduction of the so-called fetal gene program. Although hypertrophy has traditionally been considered as an adaptive response required to sustain cardiac output, in the long term, hypertrophy predisposes individuals to heart failure, arrhythmia and sudden death. Despite the recent advances in understanding the molecular and cellular processes that contribute to cardiac hypertrophy, there remains the need for further investigation.

Cellular senescence describes the permanent form of cellular proliferative arrest. Senescent cells are characterized by phenotypic changes; for example, increased cell size, enhanced senescence-associated β-galactosidase (SA-β-gal) activity and high levels of cyclin-dependent kinase inhibitors (CDKIs) which block the cell cycle. The mammalian heart has long been considered a quiescent organ. Although there are a few studies suggesting that cardiomyocytes can divide at a low rate under certain conditions, it is widely believed that the majority of cardiomyocytes, if not all of them, are out of cell cycle shortly after birth. Therefore, the question that has been raised is whether cardiomyocytes can undergo senescence. Previous studies have revealed that cardiomyocytes from old mice show certain senescence-associated properties, including high SA-β-gal activity, increased CDKIs expression, accumulated lipofuscin and decreased telomerase activity. Based on the fact that cardiac senescence and hypertrophy share defining features and signaling pathways, the aim of our study is to find out whether cardiac senescence is involved in the process of pathological cardiac hypertrophy and what could be the specific biomarkers for evaluating cardiac aging.

Our present results show for the first time that a cardiac senescence phenotype occurs in isoproterenol-induced pathological cardiac hypertrophy by analysis of a wide range of senescence markers. Similar results were also reported in an angiotensin II-induced cardiac hypertrophy model, and dilated cardiomyopathy caused by cardiac-specific Bmi1 deletion manifested by the increased ratio of SA-β-gal positive cells. It suggested that not only does cardiac senescence exist in the heart but also that it is involved in multiple hypertrophy models.


Cellular Senescence as a Cause of Aging: from Wishful Thinking to Case Closed

Today's open access review covers what is known of cellular senescence as a cause of aging, and is a very readable example of the type. It is always pleasant to find a well-written paper that can serve as an introduction for people outside the scientific community, those with an interest in the topic but only a little knowledge of the relevant biology. If you have friends who fit that description, and who are not all that familiar with the science, then you might send this over as a more gentle introduction than some of the other reviews of cellular senescence published in recent years. In particular, you might point out the middle section from which I borrowed the title for this post.

Senescent cells are those that have entered an altered state in which replication is shut down, and a range of signals and other molecules are secreted. These provoke inflammation, attract immune cells, remodel the nearby extracellular matrix, and increase the likelihood of nearby cells also becoming senescent. Senescence has several forms, occurring in response to cell damage, a toxic environment, radiation, or in the vast majority of cases as the end state of a somatic cell that has reached the Hayflick limit on cell divisions. Most species have a two-tier hierarchy of cells: a small number of stem cells that can replicate indefinitely, and the limited somatic cells that make up the vast majority of any tissue. Stem cells produce a supply of somatic cells to make up those lost to the Hayflick limit. In such a system something like senescence has to exist if somatic cells are in fact to be limited in the number of times they can replicate. Why does this two-tier system exist? Probably because it is the most accessible way to suppress the risk of cancer sufficiently well for higher animal life to evolve at all: if any more of our cells were normally capable of unlimited replication, and thus easily subverted by cancerous mutations, then our lineage could not survive over evolutionary time.

Beyond the necessity of being a full stop at the end of a somatic cell's life span, cellular senescence appears to have evolved other uses along the way. Reuse is very common in biology. Thus cellular senescence acts to set limits to growth in embryonic development, coordinates with the immune system in wound healing, and acts to suppress cancer, at least when the number of senescent cells is still low, by shutting down replication in cells that are most at risk of becoming cancerous. Senescent cells so far appear to be best as short-lived entities that self-destruct or are destroyed by the immune system quite quickly after they appear. The contribution of senescent cells to aging is produced by the tiny minority of such cells that somehow linger instead. The signals they secrete, used in the short term to carry out their evolved tasks, become destructive when issued over the long-term, and in ever increasing volume. The solution to this problem is likely very simple: destroy these cells, clearing up the remnant population that natural processes fail to eliminate. Doing so will reverse this one portion of the aging process.

Senescence in the aging process

From its initial discovery, it was postulated that senescence, on some level, was linked with organismal ageing. Modern forms of this hypothesis propose that senescent cells are produced gradually throughout life. These then begin to accumulate in mitotic tissues and act as causal agents of the ageing process through the disruption of tissue function. This conceptual model carries three underlying assumptions: firstly that senescent cells are present in vivo, secondly that they accumulate with age, and finally that an accumulation of senescent cells can have a negative impact. Each is worthy of examination.

A steady production of senescent cells is quite plausible if the kinetics whereby populations of normal cells become senescent in vitro are assumed to be similar in vivo. Many early reports evaluated findings with the mistaken underlying assumption that cell cultures become senescent because all of the cells divide synchronously for a fixed number of times and then stop. In fact, it has been known since the early 1970s that each time a cell goes through the cell cycle (i) it has a finite chance of entering the senescent state and (ii) this chance increases with each subsequent division. Thus, senescent cells appear early on if a cell population is required to divide. Indirect demonstrations that senescent cells occur in vivo, accumulate with ageing, and do so at reduced rates in organisms where ageing is slowed (for example, by dietary restriction) were occasionally published from the 1970s onwards. However, they were technically difficult to perform and correspondingly hard to interpret.

Senescence triggers changes in gene expression. A central component of this shift is the secretion of biologically active proteins (for example, growth factors, proteases, and cytokines) that have potent autocrine and paracrine activities, a process termed the senescence-associated secretory phenotype (SASP). This results in cells that overproduce a wide variety of pro-inflammatory cytokines, typically through the induction of nuclear factor kappa B (NF-κB) and matrix-degrading proteins such as collagenase. Other radical phenotypic changes, such as calcification, have also been shown to occur in some cell types with the onset of replicative senescence. The individual components of the SASP vary from tissue to tissue and, within a given cell type, can differ depending upon the stimulus used to induce senescence (for example, in fibroblasts rendered senescent by oncogene activation compared with telomere attrition or mitochondrial dysfunction). Such studies demonstrated that senescent cells could, at least potentially, produce significant and diverse degenerative pathology.

However, the observation that something can produce pathology does not mean that it must produce pathology, and a historic weakness of the cell senescence literature was that the in vivo studies essential to testing the causal relationship between ageing and cellular senescence (induced by any mechanism) were lacking. However, the production of transgenic mouse models in which it was possible to eliminate senescent cells has finally made such tests experimentally feasible. Initial studies demonstrated first that senescent cells appeared to play a causal role in a variety of age-associated pathologies in the BubR1 mutant mouse and subsequently that either life-long removal of senescent cells or their clearance late in life significantly attenuated the development of such pathologies in these progeroid animals. This clearly demonstrated that senescent cells can have significant, deleterious effects in vivo. Interestingly, the removal of senescent cells in this system was not associated with increased lifespan (an observation that demonstrated that it is possible to achieve classic 'compression of morbidity' by deleting senescent cells). However, on more conventional genetic backgrounds, attenuated age-related organ deterioration was accompanied by increases in lifespan of the order of 25%.

A justifiable claim can be made to consider these studies 'landmarks' in the field in that (i) they demonstrate a causal relationship between senescent cells and 'ageing' and (ii) the same mechanism can cause changes associated with 'ageing' as well as those associated with 'age-related disease'. These results have unusually profound philosophical implications for a scientific paper and challenge a fundamental ontological distinction that has been drawn for almost two thousand years between 'natural' ageing and 'unnatural' disease.

Whether an enhanced emphasis on basic human studies is a useful parallel-track approach to the pioneering work now taking place in rodent models or an essential next step is a matter of perspective. Many fundamental mechanisms of ageing are conserved between species, but there are often important species-specific differences. Those inclined to stress the cross-species similarities will be inclined to deprioritise human studies and vice versa. Regardless of the species of origin, the extent of variation in the phenotype of senescent cells derived from the same tissue in different individuals is not well characterised. It would be surprising if important intra-individual variation did not exist within the general population as well as 'outliers' (for example, centenarians and those with accelerated ageing diseases such as Werner's syndrome). Although data on differential SASP profiles in response to a senescence stimulus are beginning to enter the literature, they remain fragmentary concerning the senescent cell phenotype in different tissues.

Despite these gaps, progress is being made towards the development of 'senolytic' drugs that can destroy senescent cells - with the goal of duplicating the effects of the transgenic mouse models first in normal animals and eventually in human patients. Initial results seem promising.

Gene Therapy Restores Youthful Neural Plasticity in the Visual Cortex

Researchers have found that manipulating levels of the Arc gene can enhance plasticity in at least the visual cortex of the mouse brain, restoring it to youthful levels in older mice. In this recent work, the researchers demonstrate this outcome via use of gene therapy. Neural plasticity is an overall measure of the degree to which brain cells can reorganize themselves, and the pace at which new cells are created to facilitate those changes. This plasticity declines with age, and the balance of evidence to date suggests that maintaining a higher level would be beneficial for many aspects of cognitive function and health of brain tissue.

Like much of the rest of the body, the brain loses flexibility with age, impacting the ability to learn, remember, and adapt. Now, scientists report they can rejuvenate the plasticity of the mouse brain, specifically in the visual cortex, increasing its ability to change in response to experience. Manipulating a single gene triggers the shift, revealing it as a potential target for new treatments that could recover the brain's youthful potential. Additional research will need to be done to determine whether plasticity in humans and mice is regulated in the same way.

The dramatic way in which the brain changes over time has long captured the imagination of scientists. A "critical window" of brain plasticity explains why certain eye conditions such as lazy eye can be corrected during early childhood but not later in life. The phenomenon has raised the questions: What ordinarily keeps the window open? And, once it's shut, can plasticity be restored? Earlier work showed that the critical window never opens in mice lacking a gene called Arc. Temporarily closing a single eye of a young mouse for a few days deprives the visual cortex of normal input, and the neurons' electrophysiological response to visual experience changes. By contrast, young mice without Arc cannot adapt to the new experience in the same way.

If there is no visual plasticity without Arc, the thinking goes, then perhaps the gene plays a role in keeping the "critical window" open. In support of the idea, the new investigation finds that in the mouse visual cortex, Arc rises and falls in parallel with visual plasticity. The two peak in teen mice and fall sharply by middle-age, suggesting they are linked. The researchers probed the connection further in two more ways. First they tested mice that have a strong supply of Arc throughout life. At middle-age, these mice responded to visual deprivation as robustly as their juvenile counterparts. By prolonging Arc's availability, the window of plasticity remained open for longer. In the second set of experiments, viruses were used to deliver Arc to middle age mice, after the critical window had closed. Following the intervention, these older mice responded to visual deprivation as a youngster would. In this case even though the window had already shut, Arc enabled it to open once again.

The prevailing notion of how plasticity declines is that as the brain develops, inhibitory neurons mature and become stronger. Increased inhibition in the brain makes it harder to express activity-dependent genes, like Arc, in response to experience or learning. That leads to decreased brain plasticity. Normally, Arc is rapidly activated in response to stimuli and is involved in shuttling neurotransmitter receptors out of synapses that neurons use to communicate with one another. Additional research will need to be done to understand precisely how manipulating Arc boosts plasticity.


A Fragment of Klotho Improves Cognition and Synaptic Plasticity in Mice

In this open access paper, researchers report on use of a portion of the longevity-associated klotho protein to enhance cognitive function in mice. It works in both young and old mice, so is a fairly general mechanism, and may or may not be related to any of the possible roles klotho might play in the progression of aging.

α-Klotho (klotho) is a pleiotropic protein that circulates as a hormone following cleavage from its transmembrane form. It regulates insulin, Wnt, and fibroblast growth factor (FGF) signaling. Overexpression of klotho extends life in organisms, whereas lowering klotho shortens it. Elevated klotho levels in humans, resulting from genetic variation, also associate with lifespan in some populations. In model organisms and humans, levels of klotho decline with age, chronic stress, cognitive aging, neurodegenerative disease, and models of neurodegenerative disease.

We previously discovered that life-long, genetic overexpression of klotho causally enhances normal cognition and neural resilience independent of age and when broadly expressed in the mouse body and brain. It does so, at least in part, by directly or indirectly optimizing synaptic functions through NMDA receptor (NMDAR)-dependent mechanisms. Importantly, genetic, lifelong, and widespread klotho elevation also contributes to neural resilience in a human amyloid precursor protein (hAPP) model of neurodegenerative disease related to AD; that is, it effectively counters cognitive and synaptic deficits despite high levels of pathogenic proteins, including , tau, and phospho-tau. The relevance of klotho to brain health in humans is supported by the findings that elevated serum klotho, related to variation in the gene, are associated with better measures, including cognition, structural reserve of the prefrontal cortex in normal aging, connectivity between cortical regions, and physical performance in aging, and that diminished klotho levels are associated with worse brain measures.

Whether acute klotho elevation represents a strategy that can rapidly enhance cognition, motor functions, and/or induce brain resilience is a gap in our knowledge of its therapeutic potential. Here we show that αKL-F, a fragment of the α-klotho protein similar to its secreted form, can acutely improve cognitive and motor functions following peripheral administration. It does so despite apparent impermeability to the blood-brain barrier in mice. Further investigation of αKL-F-mediated molecular mechanisms revealed activation of glutamatergic signaling and enhancement of synaptic plasticity. Our findings highlight a role for αKL-F in promoting optimal synaptic functions in the normal brain and to boost "synaptic health" in aging and disease-states. Because synaptic health may confer resilience against the effects of aging and a myriad of aging-and non-aging related neurologic and psychiatric diseases, the potential to enhance it may be relevant to the human condition.


Cardiotrophin 1 Spurs Greater Regeneration Following Heart Injury

Researchers have in recent years found a number of ways to enhance regeneration in specific tissues in various laboratory species. In this one the focus is on cardiotrophin 1, and is particularly interesting when held up in comparison to what is known of the roles and relationships in heart aging from other studies of this gene. Here, researchers temporarily increase cardiotrophin 1 levels in rodents in order to produce improved regeneration of damaged heart tissue in a scenario of heart failure. Yet in the past, it was demonstrated that cardiotrophin 1 knockout mice, lacking this protein throughout their lives, live longer than their unmodified peers. This is thought to be the case because this protein spurs greater arterial stiffness and fibrosis of heart tissue, as well as greater hypertrophy as heart muscle enlarges in response to rising blood pressure and other changes that accompany aging. This hypertrophy isn't beneficial: it is a form of dysfunction, a structural alteration that weakens the heart and disarrays normal processes in ways that can lead to heart failure.

How to reconcile these opposing observations? Perhaps by looking at the way in which regeneration runs awry in old age: regenerative processes are disrupted by inflammation resulting from senescent cells and immune system failure. Fibrosis is one of the consequences, the generation of scar-like structures in place of correctly functioning tissue. Everything else being equal, more active regeneration in the heart over the long term will mean more fibrosis and consequent tissue dysfunction in this scenario, just as too little regeneration heads to a different bad end. Yet greater regeneration applied only in the short term might prove capable of more positive outcomes. Similarly for cardiac hypertrophy, if heart tissue has a greater capacity for regeneration and growth, then the possible extent of hypertrophy is correspondingly larger when it takes place over years of later life. For a short term boost in regenerative capacity that risk is diminished. This is probably an overly simplistic view; as the paper makes notes there is no clear-cut line to draw between the regulatory controls of beneficial growth and pathological growth of heart tissue.

What we might take away from this is that the rules can be very different for changes in any of the controlling mechanisms of metabolism depending on whether the long term or the short term is considered. Cellular biochemistry is complicated, and that makes it hard to find ways to manipulate it into better states that are not found normally in nature. Not that having examples in nature makes it all that much easier - look at the lack of progress towards practical calorie restriction mimetics, for example, despite this being a very easily induced and well-studied altered state of metabolism. I take this as an argument in support of the cost-effectiveness of repair-based approaches to aging and age-related disease: try to depart from the known, good biochemistry as little as possible, precisely because that is expensive and time-consuming. Instead of attempting to improve human metabolism, focus instead on repair, meaning removal of the differences between old and young tissues with the goal of restoring the known normal biochemistry of youthful individuals.

How to trick your heart into thinking you exercise: cardiotrophin improves heart health and repairs damage in lab models

Researchers have discovered that a protein called cardiotrophin 1 (CT1) can trick the heart into growing in a healthy way and pumping more blood. They show that this good kind of heart growth is very different from the harmful enlargement of the heart that occurs during heart failure. They also show that CT1 can repair heart damage and improve blood flow in animal models of heart failure. "When part of the heart dies, the remaining muscles try to adapt by getting bigger, but this happens in a dysfunctional way and it doesn't actually help the heart pump more blood. We found that CT1 causes heart muscles to grow in a more healthy way and it also stimulates blood vessel growth in the heart. This actually increases the heart's ability to pump blood, just like what you would see with exercise and pregnancy."

Heart muscle cells treated with CT-1 become longer, healthier fibres. CT-1 causes blood vessels to grow alongside the new heart muscle tissue and increases the heart's ability to pump blood. When CT-1 treatment stops, the heart goes back to its original condition, just like it does when exercise or pregnancy end. CT-1 dramatically improves heart function in two animal models of heart failure - one caused by a heart attack (affecting the left side of the heart) and one caused by high blood pressure in the lungs (pulmonary hypertension, affecting the right side of the heart). CT-1 stimulates heart muscle growth through a molecular pathway that has traditionally been associated with promoting cell suicide (apoptosis), but CT-1 has a better ability to control this pathway.

The researchers note that while exercise could theoretically have the same benefits as CT-1, people with heart failure are usually limited in their ability to exercise. The researchers have patents pending for the use of CT-1 to treat heart conditions and they hope to develop partnerships to test this protein in patients. If this testing is successful it will take a number of years for the treatment to become widely available.

Cardiotrophin 1 stimulates beneficial myogenic and vascular remodeling of the heart

Heart muscle growth, commonly referred to as cardiac hypertrophy, is a compensatory response that matches organ size to the systemic demands of the body. Hypertrophy can be a detrimental or beneficial adaptation, depending on the type of growth that occurs. In pathologic hypertrophy, heart muscle mass increases (wall thickness) without a corresponding improvement in function. Pathologic hypertrophy is generally irreversible and readily transitions to heart failure (HF), making this maladaptive process a leading cause of morbidity and mortality. Given the prominence in disease etiology, the biochemical and molecular characteristics of pathologic hypertrophy have been intensely studied and documented.

Physiologic cardiac hypertrophy is a form of beneficial remodeling, characterized by a modest increase in heart mass with improved contractile function that is reversible. Both pregnancy and endurance exercise provide well-documented means to engage this form of organ growth, a response that can also directly antagonize pathologic hypertrophy and the progression to heart failure. Akt- and MAPK-mediated signaling cascades appear to be consistent molecular signatures of physiologic hypertrophy, yet there is a paucity of definitive information regarding systemic factors that may initiate or propagate this healthy remodeling event. Insulin-like growth factor has been examined as a probable physiologic hypertrophy agonist, yet the pleiotrophic effects of this hormone may preclude its use as a bona fide cardiac restoration agent.

Cardiotrophin 1 (CT1) was originally identified as a promising hypertrophic agonist in vitro, however its expression has been more recently linked to myocardial pathology, systemic elevated blood pressure, and cardiac failure in both animals and humans. Despite these observational data implicating CT1 in certain cardiovascular diseases, this cytokine is known to bind and engage gp130 receptor complexes, a known pro-survival signal for cardiomyocytes. Therefore, we reasoned that elevated expression of CT1 in human cardiac pathologies may simply reflect a compensatory response, which attempts to curtail disease progression through the biologic remodeling activity of CT1.

Here, we demonstrate that human CT1 protein (hCT1) engages a fully reversible form of myocardial growth, and that hCT1 attenuates the ongoing pathology and loss-of-function in an aggressive and unremitting model of right heart failure (RHF). hCT1 promotes cardiomyocyte growth in part by inducing a limited activation of an otherwise pathologic hypertrophy signal, as mediated by the caspase 3 protease. In addition, hCT1 engages a cardiomyocyte-derived vascular growth signal to ensure that the modest heart muscle growth is temporally matched with a supporting angiogenic response. Moreover, two weeks administration of hCT1 in vivo produced cardiac remodeling that was similar to that induced by exercise and, in a model of progressive RHF due to severe pulmonary arterial hypertension, improved cardiac function and reversed right ventricle (RV) dilatation. These data suggest that hCT1 fulfills the criteria as a beneficial remodeling agent, with a capacity to curtail or limit an intractable form of HF.

Identification of a Potential Cause in Variability of Heart Regeneration

There is a fair degree of variation in the degree to which various mammalian lineages can recover from injury to heart tissue, but even greater differences in proficient regenerators such as zebrafish and salamanders. The heart is not a very regenerative organ in mammals, while zebrafish can regrow even sizable losses of heart tissue. Researchers here investigate a potential cause of these differences, with an eye to enhancing regenerative capacity in heart tissue via some form of therapy to adjust the underlying biochemistry that regulates regeneration.

In a recent study, researchers focused on a regenerative type of heart muscle cell called a mononuclear diploid cardiomyocyte (MNDCM). Zebrafish and newborn mammals, including mice and humans, have large numbers of MNDCMs and a relatively robust ability to regenerate heart muscle. However, adult mammals have few MNDCMs and a correspondingly limited capacity for regeneration after an injury such as a heart attack. Even so, the situation for adult mammals is not uniformly dire: the researchers observed a surprising amount of variation in the number of MNDCMs among different strains of adult mice. In some strains, MNDCMs accounted for only 1.9 percent of heart muscle cells. In others, a full 10 percent were MNDCMs. As expected, the higher the percentage of MNDCMs, the better the mice fared in regenerating their heart muscle after injury.

"This was an exciting finding. It suggests that not all individuals are destined to permanent heart muscle loss after a heart attack, but rather some can naturally recover both heart muscle mass and function. If we can identify the genes that make some individuals better at it than others, then perhaps we can stimulate regeneration across the board." Using an approach called a genome-wide association study, the researchers indeed identified one of the key genes underlying this variation: Tnni3k. By blocking this gene in mice, the researchers produced higher percentages of MNDCMs and enhanced heart regeneration. In contrast, activating this gene in zebrafish decreased MNDCMs and impaired heart regeneration. "The activity of this gene, Tnni3k, can be modulated by small molecules, which could be developed into prescription drugs in the future. These small molecules could change the composition of the heart over time to contain more of these regenerative cells. This could improve the potential for regeneration in adult hearts, as a preventative strategy for those who may be at risk for heart failure."


Reprogramming Skin Cells in situ as an Approach to Delivery of Cell Therapy

Researchers recently presented an interesting and novel approach to cell therapy based on reprogramming patient cells. The normal methodology involves taking a cell sample, then reprogramming and culturing the desired cells, and returning them to the body. In this case the process is inverted: a device capable of delivering reprogramming factors into cells via electroporation is touched to the skin, and triggered. Some of the reprogrammed cells then migrate to enhance regeneration in nearby tissues. This is probably not applicable to all or even a sizable fraction of the potential uses of cell therapy, but the researchers have found a few applications that seem to work well enough to justify further development of this approach.

Researchers have developed a new technology, tissue nanotransfection (TNT), that can generate any cell type of interest for treatment within the patient's own body. This technology may be used to repair injured tissue or restore function of aging tissue, including organs, blood vessels and nerve cells. "By using our novel nanochip technology, injured or compromised organs can be replaced. We have shown that skin is a fertile land where we can grow the elements of any organ that is declining."

Researchers studied mice and pigs in these experiments. In the study, researchers were able to reprogram skin cells to become vascular cells in badly injured legs that lacked blood flow. Within one week, active blood vessels appeared in the injured leg, and by the second week, the leg was saved. In lab tests, this technology was also shown to reprogram skin cells in the live body into nerve cells that were injected into brain-injured mice to help them recover from stroke. "This is difficult to imagine, but it is achievable, successfully working about 98 percent of the time. With this technology, we can convert skin cells into elements of any organ with just one touch. This process only takes less than a second and is non-invasive, and then you're off. The chip does not stay with you after the reprogramming of the cell starts. Our technology keeps the cells in the body under immune surveillance, so immune suppression is not necessary."

TNT technology has two major components: First is a nanotechnology-based chip designed to deliver cargo to adult cells in the live body. Second is the design of specific biological cargo for cell conversion. This cargo, when delivered using the chip, converts an adult cell from one type to another. TNT doesn't require any laboratory-based procedures and may be implemented at the point of care. The procedure is also non-invasive. The cargo is delivered by zapping the device with a small electrical charge that's barely felt by the patient. "The concept is very simple. As a matter of fact, we were even surprised that it worked so well. In my lab, we have ongoing research trying to understand the mechanism and do even better. So, this is the beginning, more to come."


A Novel View of Lysosomal Dysfunction in Neurodegenerative Disease

Autophagy is an important process, a form of cellular housekeeping in which broken proteins, damaged cell components, and other metabolic waste are tagged, packaged, and conveyed a lysosome for recycling. Lysosomes are membranes filled with enzymes and other molecular tools capable of breaking down most of what a cell will encounter in its lifetime. Most is not all, however, and over the course of a human life span lysosomes in the long-lived cells of the nervous system become weighed down with compounds they cannot effectively recycle. These lysosomes become bloated and dysfunctional, and their cells suffer due to rising levels of waste and breakage. This is, of course, a very high level and general description of a downward spiral. At the detailed level there is a great deal yet to be determined about exactly how this failure progresses.

Nerve cells, or neurons, are structurally quite different from most other cell types. They extend very long connections between one another, axons, which also need the service of lysosomes, just as much as the rest of the cell body. In the research noted below, the authors identify the failure of lysosomes to move along axons as a possible factor in the decline of autophagy in old nervous system tissue. It isn't clear how this relates to the buildup of waste in lysosomes, and in fact one might take this as only a very preliminary examination of the issue of axonal transport of lysosomes. The researchers have identified a regulator they can use to artificially degrade this transport, but that isn't the same as showing that changes in the regulator are relevant in normal aging: all it shows is that making autophagy worse - by any means - accelerates the age-related neurodegeneration that gives rise to conditions like Alzheimer's disease. We already know this to be the case, and we already know that autophagy declines in effectiveness with age. A reason for continued investigation in this case is that the specific characteristics of lysosomal failure in axons produced in this study look very similar to those occurring in Alzheimer's disease, but we should reserve judgement until further progress has been made.

The SENS rejuvenation research approach to lysosomal decline is to find ways to break down the specific molecular waste that the lysosome struggles with. The presence of this waste is a form of damage, a cause of aging, and it should be removed if aging is to be addressed. The philosophy here is that it is probably more cost-effective to make this potential repair and see what happens as a result than to take the time to first completely untangle the complexities of cellular biochemistry. Potential therapies that should improve the state of the system are in fact one of the best tools to aid in creating understanding, as success in repair establishes knowledge of causes and consequences that would be far harder to obtain through inspection only. Ichor Therapeutics is doing this for one form of waste that occurs in retinal cells, building the Lysoclear therapy for macular degeneration. In the context of the paper below, it would be most interesting to find out how the Ichor approach changes the behavior of lysosomes in retinal axons.

Scientists reveal role for lysosome transport in Alzheimer's disease progression

Researchers have discovered that defects in the transport of lysosomes within neurons promote the buildup of protein aggregates in the brains of mice with Alzheimer's disease. The study suggests that developing ways to restore lysosome transport could represent a new therapeutic approach to treating the neurodegenerative disorder. A characteristic feature of Alzheimer's disease is the formation of amyloid plaques inside the brain. The plaques consist of extracellular aggregates of a toxic protein fragment called β-amyloid surrounded by numerous swollen axons, the parts of neurons that conduct electric impulses to other nerve cells.

These axonal swellings are packed with lysosomes, cellular garbage disposal units that degrade old or damaged components of the cell. In neurons, lysosomes are thought to "mature" as they are transported from the ends of axons to the neuronal cell body, gradually acquiring the ability to degrade their cargo. The lysosomes that get stuck and accumulate inside the axonal swellings associated with amyloid plaques fail to properly mature, but how these lysosomes contribute to the development of Alzheimer's disease is unclear. One possibility is that they promote the buildup of β-amyloid because some of the enzymes that generate β-amyloid by cleaving a protein called amyloid precursor protein (APP) accumulate in the swellings with the immature lysosomes.

Researchers investigated this possibility by impeding the transport of lysosomes in mouse neurons. The researchers found that neurons lacking a protein called JIP3 failed to transport lysosomes from axons to the cell body, leading to the accumulation of lysosomes in axonal swellings similar to those seen in Alzheimer's disease patients. The swellings also accumulated APP and two enzymes - called BACE1 and presenilin 2 - that cleave it to generate β-amyloid. Neurons lacking JIP3 therefore generated increased amounts of β-amyloid. The researchers then removed one copy of the gene encoding JIP3 - halving the amount of JIP3 protein - from mice that were already prone to developing Alzheimer's disease. These animals produced more β-amyloid and formed larger amyloid plaques, surrounded by an increased number of swollen axons. "Collectively, our results indicate that the axonal accumulations of lysosomes at amyloid plaques are not innocent bystanders but rather are important contributors to APP processing and amyloid plaque growth."

Impaired JIP3-dependent axonal lysosome transport promotes amyloid plaque pathology

Amyloid plaques, a defining feature of Alzheimer's disease (AD) brain pathology, have long been recognized to contain an extracellular aggregate of the β-amyloid peptide that is surrounded by microglia and an abundance of swollen axons. These axons contain a massive accumulation of organelles that resemble lysosomes and/or hybrid organelles arising from the fusion of lysosomes with late endosomes and autophagosomes (subsequently referred to as lysosomes for simplicity). Despite their long-known and robust occurrence, the disease relevance of these lysosome-filled axonal swellings has not been established.

The high abundance of lysosomes within axonal swellings at amyloid plaques and their potential role as sites of APP processing raise questions concerning the fundamental mechanisms that govern axonal lysosome abundance. Multiple studies have identified late endosomes and autophagosomes within distal regions of axons that likely play key housekeeping functions by sequestering old or damaged proteins and organelles. However, to degrade and recycle their contents, these organelles must acquire lysosomal properties such as hydrolytic enzymes and a highly acidic lumen. To this end, these organelles are thought to undergo a maturation process within axons that is coupled with their retrograde axonal transport toward the neuronal cell body.

To test the contribution of axonal lysosomes to amyloid plaque pathology, we first sought to develop a genetic strategy to perturb axonal lysosome abundance. To this end, we identified an important role for mouse JNK-interacting protein 3 (JIP3) in regulating the abundance and maturation state of axonal lysosomes. Of particular interest, immature lysosomes accumulated in the axons of JIP3 knockout (KO) neurons in a manner that recapitulated the key molecular and morphological properties of plaque-proximal axonal lysosomes in AD, including the buildup of APP-processing machinery. Such changes in the abundance and/or localization of APP-processing proteins were accompanied by increased β-amyloid peptide production. We then tested the in vivo effect of depleting JIP3 in a mouse model of AD and found a dramatic worsening in the severity of amyloid plaque pathology. These observations support a model wherein the accumulation of lysosomes within local axonal swellings at plaques actively contributes to APP processing and plaque development and suggest that restoration of normal axonal lysosome transport and maturation could help to suppress the development and progression of AD brain pathology.

Why and How are We Living Longer?

Both healthy and overall life expectancy has gently trended upwards over the last few centuries. In recent decades the pace has been two years per decade for life expectancy at birth, and perhaps one year every decade for life expectancy at 65. If we understand aging to be an accumulation of cell and tissue damage, and we understand that no past therapies have deliberately addressed this damage, then it is probably a fair question to ask why this trend in human life span exists. Is it an inadvertent slowing of damage accumulation, the result of somewhat papering over the consequences of that damage, or some other effect? The underlying reasons for small, slow changes in complex, poorly understood systems are ever challenging to pin down, especially when so much of the evidence is statistical in nature. This leaves a lot of room to debate, particularly regarding the nature of the present trend, rather than the century-old gains in life expectancy that were most likely due to reductions in the burden of infectious disease over the life span.

As a sidebar, the author of this paper, Thomas Kirkwood, is one of a number of scientists in the field who fully embrace the concept of aging as a process of damage accumulation, but nonetheless are either ambivalent or hostile towards efforts to repair the damage in order to create rejuvenation therapies. If you look back in the Fight Aging! archives, you'll find a fair number of examples of Kirkwood sparring with Aubrey de Grey of the SENS Research Foundation, or otherwise dismissing the SENS damage repair approach. Now that senolytic therapies to clear senescent cells are undeniably mainstream, a repair approach that was part of the SENS portfolio at the outset, Kirkwood must acknowledge it. Indeed, he does so in this paper. This is how progress is going in some parts of the research community: people who rejected SENS out of hand ten or fifteen years ago, despite the compelling evidence, continue to reject SENS out of hand, except for the one piece that they now cannot ignore.

During the last decades of the 20th century, a remarkable phenomenon became apparent. Contrary to general expectation, the increase in human life expectancy - a measure of average length of life within the population - that had been occurring steadily in developed countries for almost two centuries failed to hit its predicted ceiling and has carried on at the same rate as before. To appreciate why the continuing increase in life expectancy was unexpected, it is necessary to examine what had been driving its earlier increase: cleaner drinking water, better sanitation and improvements in housing, education and nutrition all contributed, aided latterly by the development and widespread application of vaccines, antibiotics and other advances in preventive and therapeutic medicine. As the last quarter of the 20th century began, the residual levels of early- and mid-life mortality had fallen so low that any further reductions could have had only a modest effect on further increasing life expectancy.

As it was assumed that the ageing process itself was essentially immutable - a biological given - it was expected that populations would simply contain greater numbers of older people. These would die at the same ages as the oldest of their predecessors, who had been fewer in number but aged just the same. What has changed, however, is that it is now the death rates of those of advanced age - 80 and older - that are falling fastest. Put simply, it seems that the nature of old age is undergoing a significant change. Old people are, as a rule, reaching more advanced ages in better and better condition, and this is reflected in the continuing increase in life expectancy. What is likely to happen to human longevity in the future? What factors influence our individual trajectories of health into old age? How feasible is it to think of discovering new ways to extend further the duration of healthy life free of disability and disease?

The evolution of ageing is now generally understood to have occurred not through programming of ageing as an adaptive benefit in its own right, but because the force of natural selection falls off strongly across the course of the lifespan. The different longevities of different species can be explained because the exposure to accidents varies from one species to another, and consequently, selection will favour a higher investment in somatic maintenance in a species better adapted to survive the hazards of its ecological niche than in a species subject to a higher extrinsic level of risk. Comparative studies of ageing consistently reveal that cell maintenance is greater in longer-lived organisms.

A striking feature of ageing is its variability. That ageing is malleable is evident from the falling death rates in old age. The more hygienic conditions of modern life in high-income countries, with fewer sources of physical stress and earlier interventions to maintain health, most probably explain why people now reach old age physically 'younger' than their parents and grandparents. Malleability is also evident through the social gradient in health and life expectancy, whereby those of lower socio-economic status have shorter life expectancy.

Recent progress in research on ageing has generated considerable interest in the potential for science to extend the human health span, i.e. the period free of significant disease or disability, beyond the improvements that are occurring already. These include the possibilities of the following: (i) drugs targeting molecular pathways found to be involved in the regulation of lifespan, such as rapamycin and resveratrol, or enzymes such as telomerase; (ii) control of food intake through dietary restriction or intermittent fasting, to mimic longstanding observations on the life-extending effects of caloric restriction in rodents; (iii) so-called 'senolytic' strategies selectively to remove senescent cells from aged tissues and organs; (iv) transfer of plasma or serum from young to old individuals, based on pioneering studies using pairs of young and old rodents whose circulatory systems were connected; (v) repurposing of existing drugs, such as metformin, previously licensed for treatment of diabetes and now of interest for potential anti-ageing properties.

Despite the exciting potential for progress, it is important to reflect briefly on the main challenges confronting the attempts to extend the health span. The regulatory framework within which new interventions to extend health span can be developed raises particularly interesting challenges. When targeting illness, especially if it is painful and life limiting, the barriers against accepting possible side-effects are lower. Thus, anti-ageing interventions will most easily gain approval if they target late-stage diseases. However, these are not the interventions that will most effectively extend the health span. The latter interventions are ones that would need to be introduced before or as soon as possible after the earliest signs of age-related health deficits become apparent. They will therefore also be candidates for application across the population at large.

It is as yet uncertain to what extent and when science will deliver improvements in health span. Given what we know already about the general nature of the ageing process and of its malleability, it seems entirely reasonable, indeed probable, that improvements of this kind will occur. It would be wise, however, not to promise or expect too much too soon. However, the same science is likely to provide further evidence to support and encourage the kinds of changes in nutrition and lifestyle that are already known to be effective, and here it is reasonable to expect benefits to occur faster.


Calorie Restriction Enhances Learning Distinctly From Effects on Health and Longevity

In this open access paper the authors present evidence for the practice of calorie restriction, also known as dietary restriction, to enhance learning capacity via mechanisms that are separate from those related to its effects on health and longevity. An evolutionary explanation for lower calorie intake to result in better cognitive function is fairly straightforward; we might suggest that changes improving the odds of obtaining food in times of scarcity are likely to be selected. The calorie restriction response as a phenomenon is near universal in the animal kingdom, though the size of the effect varies widely, with short-lived species having a far greater increase in life span. This appears to have first evolved very early in the development of life, given that the biochemistry controlling nutrient sensing and consequent changes in metabolism is very similar across a spectrum of species ranging from yeast to humans.

Learning capacity is known to decline with age, and similar effects are also associated with several neurodegenerative diseases. Regulation of insulin signaling by dietary restriction (DR) modulates lifespan in many organisms, and it has been also shown to enhance learning and memory. However, the underlying mechanisms of these processes are largely unknown due to the difficulty in disentangling the systemic effects of DR from any potentially brain-specific effects. Here, we have analyzed the molecular effects of dietary restriction in C. elegans and show that associative learning is enhanced by reducing production of the tryptophan metabolite kynurenic acid (KYNA).

KYNA is an antagonist of glutamatergic signaling in neurons, and we find that its depletion in the nervous system upon DR allows for increased activation of an interneuron that is both necessary and sufficient to mediate learning. We investigated the effects of reductions in either insulin or mTOR signaling pathways, as well as the effects of pharmacological and genetic interventions that lead to activations of AMPK and autophagy. We show that DR and these DR mimetics each result in learning enhancements. Despite their wide-ranging cellular and organismal effects, we find that the beneficial effects of each of these interventions on learning are fully dependent on reductions in KYNA.

Finally, we demonstrate that KYNA levels have no effect on organismal lifespan, indicating that the effects of this KYNA-mediated response to dietary restriction is truly specific to brain function and not a secondary consequence of improved health or longevity. As altered KYNA levels are associated with neurodegenerative and psychiatric diseases, our results suggest that this component may be an important modulator of learning and memory in humans as well.


More Evidence for Senolytic Therapies as a Treatment for Lung Fibrosis

Research into cellular senescence as a cause of aging and age-related disease has expanded greatly these past few years. Several companies are developing approaches to safely remove these unwanted cells. Very compelling evidence has emerged for the role of senescent cells in aging; a number of research teams have demonstrated reversal of specific measures of aging in various tissues, with one study reporting extended life spans in normal mice in which senescent cells were cleared. The evidence to date is particular interesting in the case of lung conditions, especially those in which inflammation and fibrosis are prominent features. Removing senescent cells from aged mice has been shown to improve lung tissue function and elasticity. Further, senescent cells and their ability to generate inflammation have been strongly implicated in the pathology of fibrotic, inflammatory lung conditions such as idiopathic pulmonary fibrosis.

Senescent cells accumulate with age, a small lingering remnant population of the vast number of cells that every day become senescent and then self-destruct or are destroyed by the immune system. Tissues have a two-tier hierarchy of cells: the vast majority of somatic cells that can only divide a limited number of times before becoming senescent, and the small number of stem cells that can self-renew themselves over the course of a lifetime, and which act as a source of new somatic cells. In most tissues the somatic cell population turns over consistently on a timescale of days to weeks depending on tissue type: countless senescent cells are created as this happens. Near all are quickly destroyed in one way or another, but the very few that fail to achieve that goal become a significant cause of aging over the years.

Senescent cells secrete a potent mix of signals that spurs inflammation, degrades tissue structures, and makes nearby cells more likely to become senescent themselves, among other effects. The signals relate to the normal short-term roles for the senescent cells: to assist in wound healing; to rouse the immune system to clear senescent cells; to halt tissue construction in embryonic development; to suppress the risk of cancer by ensuring that the most at-risk cells become senescent. But left to continue this program for the long-term, and in increasing numbers, the result is age-related disease and failure of tissue function.

The presence of senescent cells appears to be one of the important contributing causes of the dysfunction in regeneration that occurs with aging. Fibrosis is a part of this, in essence a failure to correctly repair and restore tissue structures that involves the formation of scar-like deposits that disrupt normal tissue function. It is at least partially driven by rising levels of inflammation, and a signaling environment that upsets the normal relationship between the immune system and tissue-resident cells. Senescent cells are the most obvious culprit, and a range of studies like the one noted here present evidence in support of the role of cellular senescence in driving fibrosis and fibrotic disease. As the number of senolytic treatments capable of clearing senescent cells increases, and these treatments become more reliable and well-characterized, expect to see more and better studies on this topic in the years ahead. Human trials of senolytics to reverse fibrosis should not be more than a few years distant at this point.

Cell aging in lung epithelial cells

Pulmonary fibrosis causes the patient's lung tissue to scar, resulting in progressive pulmonary function deterioration. In particular, the surface of the alveoli (called the alveolar epithelium) is often affected. If the disease's origin is unknown, the condition is called idiopathic pulmonary fibrosis, or IPF for short. "The treatment options for IPF have been few and far between. We are therefore attempting to understand how the disease comes about so that we can facilitate targeted treatment." In the current work, researchers have now succeeded in solving another piece of the puzzle. "In both the experimental model and in the lungs of IPF patients, we were able to show that some cells in the alveolar epithelium have markers for senescence. Because the occurrence of IPF increases with age, this was already suspected. We have now succeeded in proving this hypothesis."

Senescence impairs lung function in two ways: It prevents lung cells from dividing when they need to be replaced. And senescent cells secrete mediators that further promote fibrosis. Since this effect also plays a role in cancer, the scientists were able to access an already existing group of medicines, the so-called senolytic drugs that selectively kill off senescent cells. In order to test possible treatment strategies, the scientists placed the affected cells into a three-dimensional cell culture and examined the drugs's effect ex vivo. "We observed that this caused a decline in the quantity of secreted mediators and additionally a reduction in the mass of connective tissue proteins, which are greatly increased in the disease." Altogether, the study shows that senescence in the cells of the alveolar epithelium can contribute to the development and worsening of IPF.

Senolytic drugs target alveolar epithelial cell function and attenuate experimental lung fibrosis ex vivo

The incidence of idiopathic pulmonary fibrosis (IPF) increases with age and accumulating evidence strongly suggests ageing as a crucial contributor to IPF initiation and progression. In support of ageing as one proposed driver of disease pathogenesis, normal and accelerated-aged mice are more susceptible to experimentally induced fibrosis. A landmark paper in 2013 described nine hallmarks of ageing, and importantly, all nine hallmarks have been found to contribute to IPF pathogenesis, albeit to a variable degree. Cellular senescence, representing one of these hallmarks, is characterised by stable cell cycle arrest accompanied by secretion of mediators, including pro-inflammatory cytokines and metalloproteinases, collectively termed the "senescence-associated secretory phenotype" (SASP). While the detrimental effects of senescence are thought to be a result of stem or progenitor cell depletion or of the SASP components, senescence has also been described to be beneficial in tumour suppression and wound healing.

In the lung, as in other organs, the number of senescent cells increases with age and cellular senescence has been linked to the pathogenesis of chronic lung diseases such as chronic obstructive pulmonary disease or IPF. The contribution of senescent cells to disease onset and progression remain unclear. Some studies have suggested a link between increased senescence and fibrotic burden, while others report that attenuation of lung fibrosis correlates with lung fibroblast senescence. In addition to lung fibroblasts, evidence has emerged that alveolar epithelial cells can become senescent in IPF. However, lung epithelial cell senescence and its potential pathogenic role in IPF remains largely unexplored. Here, we aimed to investigate whether senescence of this cell population is detrimental or beneficial to lung repair. We utilised senolytic drugs on fibrotic lung epithelial cells in vitro and ex vivo in three-dimensional lung tissue cultures and demonstrated that senolytic treatment attenuates fibrotic mediator expression, while stabilising epithelial cell marker expression and function. These findings suggest that senescence contributes to development of lung fibrosis and that treatment of pulmonary fibrosis with senolytic drugs might be beneficial.

Optimism without Complacency in the Matter of Rejuvenation Research

In this article, the Life Extension Advocacy Foundation volunteers offer thoughts on the middle road for expectations regarding the near future of research and development in longevity science. There are all too many people who are either overly pessimistic or overly optimistic. While it is true that the optimists of today are not in the same terrible position as the optimists of the last generation, who completely misjudged the scope of what was possible via pharmaceutical approaches to aging, it is still the case that a great deal must be accomplished in order to bring effective rejuvenation biotechnologies to the clinic. There is too little funding for many of the necessary areas of work based on the SENS vision of damage repair, and even in very well-supported and active fields such as cancer and stem cell research, comparatively little effort goes towards the most effective approaches. So while we can look back at considerable progress made in past years towards the realization of SENS-like rejuvenation therapies, and the clinical development of the first line of such therapies in the form of senolytics is forging ahead, the work has in many ways only just started.

In the last year or so we have seen remarkable progress with a number of interventions that target the aging processes to prevent and treat age-related diseases. There is plenty to be excited about, and with all this good news recently it is tempting to become overly optimistic. I have seen a significant number of people suggest that everything will be fine now, because the first technologies are starting to arrive in the repair based approach to aging, but this is a dangerous mindset to fall into. We should not think we are close to bringing the aging processes under medical control. The metabolism of the human body is a highly complex interconnected machine and anyone with an understanding of biology understands that controlling this complexity is likely the work of decades if not longer. However, there is an approach that seeks to sidestep this complexity - rejuvenation biotechnology.

Rejuvenation biotechnology is a multi-disciplinary field of science whose aim is the prevention and reversal of age-related diseases by targeting the aging processes that cause them. This is a dramatic deviation from traditional medicine and in particular geriatrics which aims to treat the consequences, often by attempting to tweak metabolism far downstream from the actual root causes, rather than prevent it happening in the first place by focusing on where the damage begins. This traditional approach of treating the symptoms and not the cause is an approach doomed to fail, and considering people continue to die from age-related diseases it is time to admit that this approach has been a spectacular failure. Repairing the underlying damage, whilst itself not trivial, is considerably less complex than attempting to tweak metabolism or treating the consequences as traditional geriatrics does. Regardless of how you categorize the damages of aging, be it the seven damages model of SENS or the Hallmarks of Aging model, they are much the same and both advocate the repair approach to aging. The damage repair approach is becoming a realistic goal in the next couple of decades and that is very good news indeed.

Some parts of the damage repair approach are now far advanced and enjoying a great deal of attention and hype in the media. But there are a number of approaches to damage that are yet to reach this level of attention. Because aging comprises of a number of interlinked but distinct processes, addressing only one or two of them is unlikely to yield significant increases in healthy lifespan. This is confirmed in rodent experiments where a single damage has been addressed. We see increased lifespans as a result of addressing these hallmarks of aging and a delay of age-related diseases, which is the aim of rejuvenation biotechnology. And yet, these animals ultimately still die of the age-related damages that are not being addressed. Believing that addressing just one form of damage will make a dramatic difference puts us in serious danger of becoming overly optimistic and thus complacent. Quite simply, there are no magic bullets.

At the risk of stating the completely obvious: we should be focusing the greatest efforts now on the areas where progress is the least advanced. We need to help these approaches that are lagging behind catch up with the rest that are more advanced. Areas like crosslink breaking, mitochondrial gene transfer and the destruction of misfolded proteins are all areas that are in need of support. As it stands these and other critical research areas that are needed to realize full medical control of the aging processes to address age-related diseases are yet to reach a proof-of-concept stage. That leaves the basic science and early-stage development of these technologies entirely in the hands of philanthropy.


Cell Therapy versus Lung Fibrosis

In recent years the research community has made some progress towards the use of cell therapies to treat fibrosis in lung tissue, the basis for a number of ultimately fatal conditions that present cannot be effectively controlled. Fibrosis is a disruption of the structure of tissue, the formation of scar-like structures that degrade tissue function. This line of research may soon be overtaken by the use of senolytic treatments to remove senescent cells, given that senescent cells appear to be a significant cause of the age-related failures in regenerative processes that cause fibrosis. Nonetheless, prior to recent work on cellular senescence and fibrosis, cell therapies were the most promising approach. Here, researchers report on recent progress in this part of the field:

Promising research points towards a possible stem cell treatment for several lung conditions, such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), and cystic fibrosis. These diseases of the lung involve the buildup of fibrous, scar-like tissue, typically due to chronic lung inflammation. As this fibrous tissue replaces working lung tissue, the lungs become less able to transfer oxygen to the blood. In the case of IPF, which has been linked to smoking, most patients live for fewer than five years after diagnosis. The two drug treatments for IPF reduce symptoms but do not stop the underlying disease process. The only effective treatment is a lung transplant, which carries a high mortality risk and involves the long-term use of immunosuppressive drugs.

Scientists have been studying the alternative possibility of using stem cells to treat IPF and other lung fibrosis diseases. Some types of stem cells have anti-inflammatory and anti-fibrosis properties that make them particularly attractive as potential treatments for fibrotic diseases. Researchers have focused on a set of stem cells and support cells that reside in the lungs and can be reliably cultured from biopsied lung tissue. The cells are called lung spheroid cells for the distinctive sphere-like structures they form in culture. Lung spheroid cells showed powerful regenerative properties when applied to a mouse model of lung fibrosis. In their therapeutic activity, these cells also outperformed other non-lung-derived stem cells known as mesenchymal stem cells, which are also under investigation to treat fibrosis.

Researchers showed that they could obtain lung spheroid cells from human lung disease patients with a relatively non-invasive procedure called a transbronchial biopsy. They cultured lung spheroid cells from these tiny tissue samples until they were numerous enough - in the tens of millions - to be delivered therapeutically. When they infused the cells intravenously into mice, they found that most of the cells gathered in the animals' lungs. The researchers then induced a lung fibrosis condition in rats that closely resembled human IPF. Then the researchers injected the new cultured spheroid cells into one group of rats. Upon studying this group of animals and another group treated with a placebo, the researchers saw healthier overall lung cells and significantly less lung inflammation and fibrosis in the rats treated with lung spheroid cells.


Recent Examples of Research into Protein Aggregates and their Clearance in the Context of Neurodegenerative Disease

Today the topic is protein aggregation in the aging brain, its consequences, and efforts to both understand and remove these aggregates. I'd noticed a few interesting research notices in the past few weeks, but they were pushed into the backlog by other matters. They are generally representative of the interest in aggregates in the research community, and of the incremental progress towards practical treatments. Removing solid deposits of misfolded or otherwise altered proteins from the brain has proven to be far more challenging than was first hoped when immunotherapies aimed at clearing the amyloid-β associated with Alzheimer's disease began earnest development more than a decade ago. There are signs of progress, and a broadening of different approaches, but it is hard to say when success will arrive in the clinic. Many of the current approaches are clearly very incremental, and even if realized as medical technologies would only produce marginal improvements.

Alzheimer's disease is where the bulk of funding goes in this part of the field, but it is only one of a score of age-related medical conditions that appear to be driven by the buildup of harmful proteins in the central nervous system. If the occasional post on the molecular biochemistry of neurodegenerative conditions here at Fight Aging! interests you, then you should consider adding ALZFORUM to your news feed. It is a good example of what can be achieved in advocacy and education if given sufficient funding. The breadth of mainstream interest in tackling Alzheimer's disease has supplied sufficient resources to fill in all of the areas of a research community, including an education and awareness arm, not just the bare bones.

Arguably this large research community should be viewed not as an effort to produce cures, but as an effort to understand the biochemistry and operation of the brain. The prospect of therapies for neurodegeneration is the rallying flag, the promised application of new knowledge that generates necessary public support. The real goal is knowledge, not treatments. At the large scale, all fields of science work this way: the pure aim of increased knowledge is funded by whatever that knowledge can be used to achieve. Absent advocacy to generate public appreciation of clear, near-future applications, it is very challenging to obtain the funding needed to perform any sort of medical research. Yet medical research is so clearly the greatest determinant of our future health and longevity that I have to see this state of affairs as an important failing of human nature. Important matters never seem to gain the focus that they merit.

Agent Clears Toxic Proteins And Improves Cognition in Neurodegeneration Models

Researchers have found cell receptors abnormally overexpressed in post-mortem brains of those with Parkinson's and Alzheimer's diseases, and that they can be inhibited in animal models to clear toxic protein buildup, reduce brain inflammation, and improve cognitive performance. These dual findings mark the first time that the receptors, discoindin domain receptors (DDRs), have been understood to play a role in Parkinson's and Alzheimer's diseases. They are primarily known as potential targets against cancer. "Activation of these cell receptors appear to prevent brain cells from cleaning out the trash - the toxic buildup of proteins, such as alpha-synuclein, tau and amyloid, common in neurodegenerative diseases."

When DDRs are over-expressed, their actions become destructive. One reason may be that DDRs are protein enzymes known as tyrosine kinases that act as on and off switches of the cell self-cleaning process known as autophagy. Excess DDRs activation may switch off autophagy, resulting in build-up of toxic proteins inside brain cells and possibly breakdown of the blood-brain barrier, common in neurodegenerative diseases. DDRs inhibition with a tyrosine kinase inhibitor appears to insulate the brain via blood-brain barrier repair, which prevents harmful immune cells that circulate in the body from getting into the brain where they can indiscriminately attack and kill healthy and sick neurons, like those that have been unable to perform autophagy. "We studied an experimental tyrosine kinase inhibitor that enters the brain and inhibits DDRs. Inhibition of these receptors with a low dose of the agent, LCB-03-110, or reduction of DDRs expression in several models of Parkinson's and Alzheimer's disease, allows nerve cells to switch on autophagy to clear toxic proteins and help the brain insulate itself from circulating inflammatory cells. This led to cognitive improvement in our animal models."

Gene variant protecting against Alzheimer's disease decreases plasma beta-amyloid levels

New research shows that the APP gene variant protecting against Alzheimer's disease significantly decreases plasma beta-amyloid levels in a population cohort. This is a significant discovery, as many on-going drug trials in the field of Alzheimer's disease focus on decreasing beta-amyloid levels in the brain tissue. According to the study, the APP A673T gene variant, which is a variant in the amyloid precursor protein gene protecting against Alzheimer's disease, leads to an average of 30 per cent decreased levels of the beta-amyloid subtypes 40 and 42. The effects of this previously discovered gene variant were analysed by utilising data from the METSIM (METabolic Syndrome In Men) study.

Approximately 0.3% of the population are carriers of the APP A673T gene variant. Although the variant itself is rare, the observed association with decreased plasma beta-amyloid levels is important from the viewpoint of Alzheimer's drug trials. Several on-going drug trials for Alzheimer's disease focus on decreasing beta-amyloid levels in the brain tissue. The findings from the population cohort in eastern Finland show that a life-long decrease in beta-amyloid levels is not associated with detrimental effects on lipid or glucose metabolism, or on any other metabolically relevant events.

Steering an enzyme's "scissors" shows potential for stopping Alzheimer's disease

Scientists have identified a couple of crucial steps in the formation of a protein called amyloid beta, which accumulates in clumps, or "plaques," in the brains of people with Alzheimer's disease. Those discoveries inspired efforts at disrupting the biochemical carving of amyloid beta's precursor protein into its final, toxic shape. The latest drugs being tested try to silence an enzyme, called BACE1, that cuts the precursor protein. But BACE1 has other functions that are beneficial, so stopping it altogether could bring unwanted side effects - including disrupting the production of myelin, the protective insulation of brain cells. Researchers have found that changing where the cut is made - in effect, guiding the enzyme's scissors to a different point - could achieve the same goal, with less collateral damage.

Researchers built upon two discoveries in the past decade of two rare mutations: one, found in Italian people, that leads to early onset Alzheimer's disease, and another, found in Icelandic people, that staves off Alzheimer's disease. The team was particularly intrigued by the diametrically opposite effects of both mutations because they affected the same point on the precursor protein's chain of 770 amino acids, swapping one acid for another. The researchers injected one set of mice with a virus carrying the Italian gene mutation, and another set with the Icelandic mutation. They found that the amino acid substitution affected where the precursor protein was cleaved. The Icelandic mutation resulted in a shortened form of amyloid beta, which does not become "sticky" and turn into plaque. The Italian mutation produced a longer, "stickier" version of amyloid beta, which ultimately becomes neuron-smothering plaque. Actually, the effects were a matter of degree: Each mutation led to more cuts in one location or more cuts in the other location. But in the gradual degradation of Alzheimer's disease, that could be enough - reducing the levels of the offending toxin could translate into many more years of life before cognitive decline sets in.

AgeX Therapeutics

AgeX Therapeutics is a spin-off of BioTime, one of the earliest of the present generation of stem cell therapy companies, and run by a fairly vocal supporter of the idea that stem cell treatments have the potential to help address aging. Considered as a whole, the stem cell field, for all of the tremendous progress made to date, actually hasn't moved far towards the classes of therapy that would be required to address the roots of stem cell population decline in aging. Treatments have instead been compensatory, or attempts to enhance regeneration, or attempts to reduce inflammation, or tissue engineering for transplant, or attempts (largely failed so far) to increase the numbers of a specific cell type in situ. All of these have some small overlap with issues involving age-related tissue damage and stem cell decline, but only a small overlap.

AgeX Therapeutics is perhaps of interest to our community for the fact that Aubrey de Grey of the SENS Research Foundation has taken a position there, more than his usual presence on the advisory board of a relevant venture. In addition, the company has recently raised funding from investors that include Jim Mellon's and Michael Greve's funds. So it seems worth looking more closely at the lines of development here than one would for the average stem cell therapy startup, to speculate on how this would lead to classes of therapy closer to the SENS vision for addressing cell loss and stem cell dysfunction in aging. We shall see how it progresses.

AgeX Therapeutics, Inc. is a biotechnology company formed in 2017 as a subsidiary of BioTime, Inc. Its mission is to apply technology related to cell immortality and pluripotency to human aging and age-related disease. The Company's technology platform has three facets: Pluripotent stem cell-derived progenitor cell lines representing over 200 types of cells in the body (PureStem technology); HyStem matrices; and induced tissue regeneration (iTR) - the latter being an emerging technology directed at inducing the immortal regeneration of tissues in the body. ​

Through BioTime, AgeX has license to a large consolidated technology and patent estate including technologies invented at Geron and subsequent companies. AgeX is leading off with cell-based regenerative therapeutics for significant unmet needs in age-related disease such as type II diabetes and ischemic disease. In addition, it will also be advancing products based on an entirely new technology platform aimed at the central molecular processes of aging itself designated "induced Tissue Regeneration (iTR)." AgeX scientists believe that the combination of telomerase therapy and iTR may unlock the potential of immortal tissue regeneration in humans.

Some naturally-occurring animals such as the Mexican salamander can profoundly regenerate damaged tissues. Humans also have this potential, but only in the first weeks of development. Using advanced molecular and artificial intelligence technologies, we have identified pathways we believe may provide means of unlocking this profound biology in human medicine. The pathways suggest that they may also be integral to the biology of aging and cancer as well. Patents relating to this emerging technology have been filed and animal studies are currently underway. The combination of pluripotent stem cell and iTR technology may provide AgeX with a valuable platform to address large markets associated with chronic degenerative age-related disease.


Converting Effector T Cells into Regulatory T Cells

Slow progress is being made in the development of means to adjust the operation and configuration of the immune system, especially when it comes to damping inflammation. Present approaches used in the clinic are blunt, suppressing immune activity as a whole, or at least large swathes of it, and have significant side-effects. More sophisticated ways to adjust immune cell behavior may have applications in reducing some of the consequences of the disarray of the immune system that occurs with age. In particular, if the chronic inflammation and overactivity of the aged immune system could be reduced, some benefits might be realized. In the longer term, however, the real relevance of this sort of work is as a stepping stone towards a greater capacity to arbitrarily adjust the immune system in situ, changing or destroying very specific subpopulations of immune cells in order to achieve desired effects. It is possible that this could lead to the prevention of misconfiguration and change in relative numbers of immune cells that occurs with age.

Scientists have revealed, for the first time, a method to reprogram specific T cells. More precisely, they discovered how to turn pro-inflammatory cells that boost the immune system into anti-inflammatory cells that suppress it, and vice versa. The researchers studied two types of cells called effector T cells, which activate the immune system to defend our body against different pathogens, and regulatory T cells, which help control the immune system and prevent it from attacking healthy parts of its environment.

By drawing on their expertise in drug discovery, the team identified a small-molecule drug that can successfully reprogram effector T cells into regulatory T cells. Their study describes in detail a metabolic mechanism that helps convert one cell type into another. This new approach to reprogram T cells could have several medical applications. For instance, in autoimmune disease, effector T cells are overly activated and cause damage to body­­. Converting these cells into regulatory T cells could help reduce the hyperactivity and return balance to the immune system, thus treating the root of the disease. In addition, the study could improve therapies using stem cells. At least in theory, producing regulatory T cells could promote immune tolerance and prevent the body from rejecting newly-transplanted cells.

"Our work could also contribute to ongoing efforts in immunotherapy for the treatment of cancer. This type of therapy doesn't target the cancer directly, but rather works on activating the immune system so it can recognize cancer cells and attack them." Many cancers take control of regulatory T cells to suppress the immune system, creating an environment where tumors can grow without being detected. In such cases, the team's findings could be used to transform regulatory T cells into effector T cells to strengthen the immune system so it can better recognize and destroy cancer cells.


Reviewing the Commercial Application of Longevity Science

In the open access paper I'll point out today, João Pedro de Magalhães, a long-standing member of both the transhumanist and aging research communities, casts an unbiased eye over present commercial efforts to treat aging as a medical condition, to slow or reverse its effects. The small online transhumanist community that blossomed with the advent of the web over the course of the 1990s includes many alumni who went on to join the scientific community, found biotechnology companies, write books, become advocates, or in other ways influence the course of today's world, now on the cusp of building rejuvenation therapies. Discussions of radical life extension, technological acceleration, and artificial general intelligence were far more fringe concerns back then than is now the case, but this growth in awareness isn't a coincidence. Visions slowly become reality because people work to make that happen. Technological progress is not accidental: it is led by our desires.

I should say that de Magalhães is here generous in not passing judgement on the value (or lack thereof) of most of the various ventures and classes of approach he surveys. But some approaches are definitely better than others, and to my eyes one the principal challenges at this time is to ensure that the effective (damage repair to reverse aging) rather than ineffective (metabolic alteration to slow aging) lines of research obtain significant support and funding. I think that there is definitely the need for some kind of metric to assess the utility of various efforts to address aging. Given figures for investment in a field, number of life span studies in various species, and average size of effect, one could potentially construct an Effectiveness Score to distinguish between fields that are absorbing a great deal of funding to no effect versus those that are more promising. I'd want an algorithm that clearly differentiates between, say, pharmaceutical targeting of mTOR, development of calorie restriction mimetics as a whole, and senolytics in terms of cost-effectiveness. I would expect the latter to be far more cost effective based on present data and the time and funding required to obtain that data. Sadly I suspect that no-one in the field has much of an incentive to participate in such an assessment, and obtaining the funding numbers wouldn't be an easy task.

The Business of Anti-Aging Science

The dream of fending off old age is as old as human civilization. Given the global aging of the population, developing interventions that preserve health in old age and postpone the onset of age-related diseases is more important than ever. In addition, we now know that it is possible to retard aging in animal models. Various genetic, dietary, and pharmacological interventions have been shown to increase lifespan, in some cases dramatically (tenfold is the current record), in short-lived model organisms like yeast, worms, flies, killifish, mice, and rats. Importantly, life-extending interventions not only increase longevity but can retard the onset of age-related diseases, resulting in the extension of healthspan (i.e., the length of time one lives in good health). These breakthroughs in the biology of aging and its impact on health and disease, referred to by some as 'geroscience', have led to the promise that we will be able to delay or slow human aging, resulting in unprecedented health benefits.

Leading causes of death worldwide, and notably in industrialized countries, are age-related diseases like cardiovascular diseases, cancer, and neurodegenerative diseases. Because of the strong relationship between the aging process and age-related diseases, the benefits emerging from anti-aging science have enormous potential. Using a model of future health and spending in the USA, the effect of delayed aging resulting in 2.2 years additional life expectancy would yield US$7 trillion in savings over 50 years; whereas addressing single pathologies such as cancer and heart disease would yield less, mostly due to competing risks. Given its huge potential financial benefits, anti-aging science has tremendous commercial opportunities. The anti-aging industry has struggled in the past in terms of reputation, but driven by more recent scientific breakthroughs it has been growing substantially with several young companies supported by world-leading brands.

As with most diseases, traditional pharmacological approaches are the most straightforward and widely explored way to target aging. Notable examples of anti-aging drug discovery efforts include pharmacological manipulations of sirtuins, sirtuin 1 (SIRT1) in particular (targeted by resveratrol), and TOR (targeted by rapamycin), which are currently being explored. TOR inhibition by rapamycin results in increased lifespan from yeast to mammals. In a small but groundbreaking clinical trial by Novartis, rapamycin improved immune function in elderly volunteers. Because rapamycin has various side effects, companies and laboratories are trying to develop safer analogs, known as 'rapalogs'. Research on resveratrol and sirtuins was high profile in 2008 when GlaxoSmithKline (GSK) purchased the sirtuin-focused biotech company Sirtris (based on work at Harvard Medical School) for US$720 million. Enthusiasm for resveratrol and sirtuins as anti-aging compounds has arguably declined in more recent years. Briefly, results have been largely disappointing since then. While Sirtris demonstrated that anti-aging biotech companies could rapidly grow in value and become a financial success for founders and early investors, its more recent problems might have hurt subsequent anti-aging science-based enterprises by discouraging investors and entrepreneurs.

Antioxidants have been historically a major focus of the field. However, currently the idea that antioxidant pathways play a major role in aging is being challenged, and epidemiological studies have largely failed to support the supposed benefits of antioxidants. While many dietary supplements still focus on antioxidants, few companies in the field maintain such a focus.

Telomeres, the protein-bound structures at the ends of chromosomes, shorten with cell division and, at least in some tissues, with age. Although genetic manipulations of telomerase in mice have yielded conflicting results, one study found that overexpression of telomerase in adult mice led to a 24% increase in median lifespan while not increasing the incidence of cancer. Therefore, the idea of activating telomerase as anti-aging remains a powerful one, even resulting in one self-experiment using gene therapy by BioViva.

Telomere shortening, as well as various stressors, can cause proliferating cells to stop dividing and enter a proinflammatory senescent state. There is evidence that senescent cells accumulate with age, at least in some tissues. In a landmark study, drug-induced clearance of p16Ink4a-positive cells (a marker of senescence) once per week from age 1 year extended the median lifespan in two normal strains of mice by 24-27%. Tumorigenesis and age-related deterioration of heart and kidney were delayed or slowed. As a consequence, Unity Biotechnology, a company founded by researchers at the Mayo Clinic involved in the above-mentioned work as well as the Buck Institute, has raised US$116 million from investors to develop senolytic (i.e., an agent that destroys senescent cells) treatments. Continuing research by the cofounders has focused on senolytic agents, including the killing of senescent fibroblasts with piperlongumine and ABT-263. Interestingly, they have also acquired a patent related to a senescent cell antibody for imaging and delivery of therapeutic agents.

Other companies focusing on senolytics include Oisin Biotechnologies, although, according to their website, they seem to be developing a genetically targeted intervention to clear senescent cells, suggesting a different approach than Unity. Moreover, Everon Biosciences has shown that a significant portion of cells with p16Ink4a expression may be a subclass of macrophage termed senescent associated macrophages (SAMs). Following this discovery Everon has announced that they will focus on these SAMolytic agents. Last, Siwa Therapeutics' focuses on developing antibodies against senescent cell markers capable of identifying and removing senescent cells.

With a decidedly Silicon Valley-based confidence, venture-capital funded big-data approaches are being pursued in aging and longevity science. High-profile players include Calico and Human Longevity Incorporated (HLI). Started as one of Google's moonshot projects in 2013, Calico is attempting to harness big data to improve understanding of the basic biology that controls lifespan. Not much is known about how this will look in practice. HLI is focused more directly on data than Calico and aims to create the largest database of integrated high-throughput assays - genotype, transcript, and microbiome data - along with deep phenotypic data on patients to fully map genotype to phenotype to inform health care in general. Published efforts have focused on deep sequencing of human genomes. Other companies are using big-data techniques to find new uses for already approved drugs. For one project Insilico Medicine uses deep learning on multiple 'omics' data types to find new relationships between existing drugs and gene regulatory pathways effected in, or otherwise related to, aging-related diseases.

In addition to reasons for spending on basic research in general, anti-aging science has unusual potential to benefit from market forces due to particularly favorable demographics. The median wealth of US families aged 62 years or older is over US$200,000, compared with US$100,000 and US$14,000 for middle-aged and young families, respectively. This may in part be responsible for the increase in investment in even non-traditional therapies and direct to consumer (DTC) products and services aimed at extending healthy lifespan. One high-profile DTC company is Elysium Health, which sells its Basis pill directly to consumers. Basis contains an NAD+ precursor, nicotinamide riboside, that declines with age and is required for sirtuin activity. Elysium has already concluded a preregistered, 2-month randomized, double-blind Phase I trial for Basis using 120 healthy 60-80-year-olds. While results have yet to be published, a company press release claims that participant's blood NAD+ levels were increased by 40% for the duration of the second month. However, the release did not mention the results for health measures.

Caloric restriction (CR) is the most studied and most consistent intervention that increases both health- and lifespan. While a CR diet is too harsh for most people, intermittent fasting (IF) has been proposed as a less-restrictive alternative. Based on this premise, L-Nutra was created to develop and market proprietary fasting-mimetic meals designed to provide the beneficial effects of IF.

A growing number of companies are now focusing on anti-aging science. In a way this is surprising, given that the first high-profile anti-aging company, Sirtris, while a success as an early investment has thus far failed to live up to its anti-aging expectations. Modern advances, abundant aging-related targets and an aging population can arguably be driving the current crop of anti-aging biotechs, but how realistic is it that these will succeed? In a sense there are few assumptions of which we can be confident. At present we can state that: (i) aging is a complex process; (ii) although there are numerous theories of aging with vocal advocates, there is no consensus among scientists regarding the underlying causes of aging; and (iii) aging can be manipulated in short-lived model systems by genetic, dietary, and pharmacological intervention. However, that leaves many open questions, so the uncertainty concerning human anti-aging approaches remains very high.

Although findings from short-lived model organisms, particularly in terms of the plasticity of aging, have been a major breakthrough in the field, the degree to which they are relevant to humans is unknown. Human homologs of genes associated with aging in model organisms have been associated with human longevity in some cases, but these are rare and thus our understanding of the genetic basis of human longevity remains largely unknown. Therefore, it is plausible that most findings from short-lived model organisms will not be relevant to human beings. Briefly, not only may the pathways necessary to extend lifespan in model systems be often irrelevant to the comparatively long-lived human species. Given the above concerns, a major open question is how effective anti-aging interventions can be in humans. Even if they have benefits, how do these compare with mundane lifestyle choices like going to the gym?

Of the 4000 private and 600 public biotech companies worldwide, only a few percent have shown increasing profitability. Historically, only one in 5000 discovery-stage drug candidates obtain approval and only a third of those recoup their R&D costs. Besides, the success rate of clinical trials is not improving, although we have more information, data, and potential targets than ever before. Given the various constraints on the study of aging, including the reliance on short-lived model organisms, long validation times, and poor biological understanding, it would be surprising if most of the companies described here are active a mere 5-10 years from now. Likewise, most companies in the anti-aging biotech sector are startups, and thus riskier. From an investor's perspective this means that investors in anti-aging biotech are expecting to lose money but hoping to win big.

Omics approaches are imperative, as is a multidisciplinary outlook, but while these have augmented the search space, attrition rates remain very high. Perhaps surprisingly, despite the so-far failure of Sirtris, which would be expected to hurt the industry, anti-aging biotech is more vibrant than ever. Clearly even such high-profile failure has not dissuaded investors, including many tech billionaires. No doubt new technologies will be developed and new targets discovered in the coming years and decades, possibly opening new avenues for the commercialization of aging in other directions. The promise of fending off old age remains more powerful than ever and the financial gains for any company delivering on that promise will continue to be extremely attractive. Anti-aging biotech can then be seen as an extreme reflection of the biotech sector: risky and most likely to fail, but if one company is successful the outcomes are monumental.

Do Chimpanzees Suffer from Alzheimer's Disease?

Researchers here report on the presence of protein aggregates characteristic of Alzheimer's disease in old chimpanzees. This may not result in any meaningful new lines of investigation, however, given that studies of this species are now heavily restricted. In principle, comparative biology studies using similar, related species can be useful in helping to understand specific mechanisms and cellular behaviors. In the case of Alzheimer's disease, any of the benefits that might result from such a research program may well be overtaken by success in any one of the numerous forms of therapy currently under development. Comparative biology is a useful approach, but successfully removing a possible cause, such as one type of protein aggregate, and then observing the effects is even better as a source of new information.

Researchers have discovered tell-tale signs of Alzheimer's disease in 20 elderly chimpanzee brains, rekindling a decades-old debate over whether humans are the only species that develop the debilitating condition. Whether chimps actually succumb to Alzheimer's or are immune from symptoms despite having the key brain abnormalities is not clear. But either way, the work suggests that chimps could help scientists better understand the disease and how to fight it - if they could get permission to do such studies on these now-endangered animals.

A definitive diagnosis of Alzheimer's includes dementia and two distortions in the brain: amyloid plaques, sticky accumulations of misfolded pieces of protein known as amyloid beta peptides; and neurofibrillary tangles, formed when proteins called tau clump into long filaments that twist around each other like ribbons. Many other primates including rhesus monkeys, baboons, and gorillas also acquire plaques with aging, but tau tangles are either absent in those species or don't fully resemble those seen in humans. In the new study, and thanks to a newly founded center that collects brains from chimps that die at zoos or research centers, the team was able to examine the brains of 20 chimps aged 37 to 62 - the oldest recorded age for a chimp, roughly equivalent to a human at the age of 120. Of these chimps, 13 had amyloid plaques, and four also had the neurofibrillary tangles typical of more advanced stages of Alzheimer's in humans.

But so far, only humans are known to show the Alzheimer's trifecta of plaques, tangles, and dementia. The 20 chimps whose brains were studied had not been tested for cognitive or behavioral changes. As a result, "we can't say these chimps had Alzheimer's, but we can say for sure that they are the only other species with its pathologic hallmarks." Some scientists aren't persuaded that the chimp brains really do match those of human Alzheimer's patients. In human brains, amyloid plaques are associated with neuron death, which wasn't measured in the new study. The researchers plan to go back to the same chimp brains to calculate neuron death, but proving that chimps develop dementia will require research on living animals.


Reviewing Epigenetic Inheritance of Longevity

Natural variations in longevity can be inherited to some degree, but one of the more interesting findings in recent years is that induced longevity as a result of environmental circumstances such as calorie restriction or gene therapies applied to adults only, and thus not inherited, can also produce extended longevity in offspring. Researchers were initially quite surprised to find that even limited forms of Lamarkian inheritance could exist. The proposed mechanism is inheritance of epigenetic markers, decorations to DNA that control the degree to which specific proteins are produced from their genetic blueprints. This open access paper reviews what is known on this topic.

Until recent years, a basic assumption in biology was that mutations in the DNA sequence were the only source of heritable phenotypic variation. It is commonly believed that genetic information may be transmitted to the next generations by germ cells only, while somatic cells do not have any inheritance function. The core of this theory is the idea that information is not capable of being transferred from somatic to germline cells and, respectively, to the next generations. This concept is commonly referred to as the Weismann's barrier. According to this concept, a strict distinction exists between innate and acquired characters. There is, however, significant empirical evidence to suggest that the Weismann's barrier is not entirely impermeable and can be crossed.

Examples for non-DNA sequence-based inheritance across generations have been obtained in a variety of species, including microbes, plants, worms, flies, fish, rodents, pigs, and humans. Many recent papers highlight the role of epigenetic mechanisms in mediating these effects. These processes include modified patterns of DNA methylation and histone posttranslational modifications, replacement of canonical histones with histone variants, as well as altered noncoding RNA expression causing changed local accessibility to the genetic material and modified gene expression. In several recent studies, the potential importance of non-genomic transgenerational effects in the inheritance of age-related characteristics has been highlighted. However, the transgenerational effects on longevity have been reported only rarely to date. Most of the papers reviewing and discussing such effects are focused solely on data obtained from the nematode Caenorabditis elegans, although similar findings were obtained in other species as well.

In evolutionary terms, the transmission of the adaptive transcriptional patterns acquired throughout the parental life course in subsequent generations via the mechanism of epigenetic memory can enable the organism to better survive in potentially adverse environments. In particular, it has been repeatedly reported that offspring of parents exposed to nutritional stresses exhibit altered expression of genes related to metabolic functions including those implicated in pro-longevity metabolic pathways. The mechanisms potentially responsible for such inter- and transgenerational effects are currently the subject of active investigation. In most studies on short-lived models such as nematodes and flies, the role of histone modifications in transgenerational transmission of epigenetic information was highlighted, while in rodent models changes in DNA methylation have been mainly detected.


A Short Interview with George Church on Genetics and the Treatment of Aging

The Life Extension Advocacy Foundation volunteers recently interviewed George Church, one of the leaders in the research community who has come around these past few years to speak out in public as being very much in favor of treating aging as a medical condition. I point this out largely because they ask about some of his recent comments regarding timelines in the near future development of anti-aging therapies. He thinks that the first are only a few years away, which is indeed true from my perspective given what is happening in the development of senolytics to clear senescent cells, but Church doesn't have senolytics in mind when he says this. He is one of the luminaries of modern genetic biotechnology, and he sees the future through that lens.

Professor George Church - Turning Back Time to End Age-related Diseases

You recently said that you "predict we are about to end the aging process. In the next five years no less!" Whilst progress has indeed been rapid in the field of rejuvenation biotechnology, could you clarify, is this five years to achieving this in human cells, to clinical trials or what exactly?

Within five years it seems plausible to have some gene therapies in FDA approved clinical trials in dogs - aimed at general aging reversal, but quite likely, labeled for specific diseases (and in humans soon thereafter). This means combinations of gene therapies aimed at most of the known major aging pathways, though there are major challenges in efficient delivery.

Do you agree that epigenetic alterations as described in the Hallmarks of Aging are a primary driver of the aging process, and if so do you think we can safely use cell reprogramming factors OSKM (OCT4, SOX2, KLF4 and MYC) to turn back cellular aging?

Yes. Epigenetics are important drivers, but it are only part of the Hallmarks of Aging - and OSKM would, in turn, be only part of that. Other examples are factors behind heterochronic parabiosis. Efficacy may depend on the various tissue types.

DNA damage is proposed to be a primary reason we age. Can it be repaired by targeting TFAM (Transcription factor A, mitochondrial precursor) to increase NAD (a coenzyme in all living cells that facilitates the production of energy) levels that are known to facilitate DNA repair?

We have targeted TFAM and consequently raised NAD successfully. The NAD-facilitated repair is not the only route - we can prevent DNA damage (via the management of radical oxygen species), prevent the impact of such damage (e.g. duplicating tumor suppressor genes), favor specific types of DNA repair, or induce apoptosis in cells which appear to acquire potentially oncogenic mutations.

Cancer is caused by an unstable genome resulting from DNA damage and could be considered the poster child of aging diseases, can we use CRISPR to defeat cancer?

Genome editing (TALENs, CRISPR, etc.) and transgenic methods (CART) are being 'successfully' applied, but proof of generality and long remission is not here yet. Effective alternatives are preventative - vaccines against some of the 11 infectious, cancer-causing agents (e.g. HPV), inherited genome sequencing, genetic counseling, prophylactic surgery and avoiding environmental risk factors. Some strategies which work to preventatively reduce cancer in mice might benefit from engineering germline or more efficient delivery of gene therapies (since single untreated cells matter more for cancer than other diseases).

Do you think we can learn useful knowledge that can be applied to humans from the whole-genome sequencing of long lived species such as the 400-year-old greenland shark?

The most promising sequencing insights will probably come from genomes closest to average humans, such as naked mole rat, bowhead whales and human supercentenarians. Even more crucial is low-cost, high-accuracy testing of hypotheses flowing from those sequences, plus already hundreds of hypotheses from model organisms and cell biology (see the GenAge database).

Genetics is an enormous area, even when you narrow down the scope to genetic biotechnologies that can be used to build therapies relevant to aging. There are numerous different things going on, not all of which we should be equally enthused by. I'll draw some fairly arbitrary lines here to demarcate three classes of genetic therapy. The first broad class of work is very similar to existing pharmaceutical development: the construction of means to temporarily alter the level of a particular protein or interfere in one or more interactions carried out by this protein. Genetic technologies hold the promise of being able to carry out this task with far greater accuracy and control over the size of the outcome. The second class of work involves the creation of permanent effects by adding or removing DNA in a targeted fashion, such as to provide a functional copy of a gene that is broken as a result of an inherited mutation. This is not yet practical for therapies applied to human adults due to challenges in obtaining reliable, comprehensive cell coverage, meaning introducing the new DNA into enough cells, and especially stem cells, to produce a significant and lasting effect. But that goal lies very close in the near future.

The third class of work involves more complicated use of genetic machinery. The production of programmable DNA machines that can read cell state, react, and carry out logical operations to produce different outcomes for different circumstances, for example. The Oisin Biotechnologies approach to targeted cell destruction is one such early, simple machine. Far more complex machinery is obviously possible, given the existence of cells in the first place. This class of more complicated uses also include applications of gene therapy that achieve a more devious and multi-layered goal than just inserting a gene that will result in proteins being produced. For example, allotopic expression of mitochondrial genes involves inserting altered versions of mitochondrial genes into nuclear DNA, their usual sequences wrapped in such a way that cellular transport machinery will pick it up these altered proteins, move them back to the mitochondria, and then import them into mitochondria, ending up with a copy of the original protein at the end of that process.

Now, much of the first category of genetic engineering, tinkering with levels of specific genes, will be just as marginal for the treatment of aging as the pharmaceutical approaches that preceded them. That is inherent in the proteins and genes being targeted. When the goal is mimicking the response to calorie restriction, or increasing autophagy, or similar alterations shown to modestly slow down aging in laboratory animals, then the small size and lack of reliability in the outcome is as much inherent in the target as it is in the method used to manipulate the target. These mainstream efforts are only slightly increasing resistance to the consequences of molecular damage in aging, or slightly slowing the accumulation of that damage. They are not truly effective means of addressing aging.

We should nonetheless expect to find that some targets accessible to genetic methods are a lot better than those that can be or have been manipulated via drugs. There are some promising genetic variants that exist in the wild and have far larger effects on human cholesterol levels than the best drugs, such as statins, for example. There is myostatin and follistatin, that can be targeted to increase muscle growth to a far greater degree than any pharmaceutical method, and thus resist age-related loss of muscle mass. But these are still not repair therapies. They are only ways to better compensate somewhat for the losses and damage of aging. The damage will still win if it is not addressed.

So what George Church describes in the short term is really just the application of genetics to the ongoing pharmaceutical tinkering with metabolism that has achieved little of any practical use in the past few decades. All that has been gained is knowledge. What he describes in the longer term is the much more ambitious project of rebuilding the human genome, one small step at a time, to create packages of changes that result in slower aging, greater resistance to the consequences of aging, and other enhancements to the human condition. This is an immense project of vast scope and complexity. It will happen in the fullness of time, but it cannot possibly produce anywhere near as good an outcome in the next few decades as the alternative approach of keeping the present baseline human genome unmodified, and focusing on periodic repair of the molecular damage that arises as a side-effect of the normal operation of metabolism. The research community has a far better roadmap for this goal, there is far less to achieve, and it is a much easier set of projects, where far more is known of what must be done. Genetics with the goal of improving humanity is seductive, as the long-term potential is truly amazing - but unless we address the damage first, we'll all be long dead before that potential is reached.

Longer-Lived Mice Better Resist Immune System Decline

In this open access paper, researchers examine the functionality of the immune system in old mice. They find a correlation between greater longevity and more successful compensation for age-related changes. Longer-lived mice tend to have immune systems capable of better, less disrupted function in later life. Given the importance of the immune system to many aspects of tissue function, over and above its role in defending against pathogens, this should perhaps not be all that surprising. Open questions remain on the relevant mechanisms and the degree to which sustained immune performance is a matter of resisting damage versus better compensating for damage versus stochastic differences in the load of molecular damage between individuals.

Aging of the immune system, which is known as immunosenescence, involves a striking rearrangement of almost every component, leading to changes including enhanced as well as diminished functions. In addition, the functioning of the immune system has been demonstrated to be an excellent marker of health, given that several age-related changes in immune functions are predictive of mortality and lifespan. Thus, long-lived individuals seem to exhibit a high degree of preservation of several functions of the immune system with values similar to those observed in adult individuals. This may be essential to reach a very advanced age in a healthy condition.

Among all the age-related changes that the immune system undergoes, the most obvious is the involution of the thymus gland. Accordingly, one of the most marked age-related alterations in the immune cells has been reported in the T lymphocytes, specifically in the lymphoproliferative response to mitogens, which is decreased in old subjects for both humans and experimental animals. The study of the proliferative response of leukocytes to a given stimulus has become an important issue given that a low lymphoproliferative response to mitogens has been linked to an increased mortality, and together with other parameters, defines the immune risk phenotype in humans.

Cytokines are principal mediators of interactions among immune cells. They are responsible for the development and resolution of immune response and are greatly affected by the aging process. In fact, an age-related loss of homeostasis in cytokine networks can contribute significantly to health impairment in old age. In this context, together with the previously mentioned age-related loss of functionality in immune cells, aging is characterized by a chronic low-grade inflammatory status, so-called "inflammaging". Thus, it has been described that an age-related increase in release of pro-inflammatory cytokines in resting cells leads to a sterile inflammation. This is accompanied by an elevation of circulating levels of cytokines in old subjects, such as IL-6, which in addition has been related to a higher risk of mortality. However, cells from old subjects produce lower pro-inflammatory cytokines when needed to do so, i.e., after a mitogenic stimulus, compared to those of adult subjects. Again, long-lived individuals, despite having high levels of pro-inflammatory markers, have a postponed disease onset, making it difficult to understand whether "inflammaging" is beneficial or detrimental.

Based on the striking facts regarding lymphoproliferation and cytokine release by immune cells in long-lived individuals, it was hypothesized that these individuals could present different proliferative as well as cytokine release dynamics as an adaptive mechanism. Moreover, given that all the studies in long-lived individuals previously mentioned have been cross-sectional, it is still not known if they reach those advanced ages due to the maintenance of optimal immune cell function during their whole life (as if they were adults) or whether they experience an age-related impairment in these functions but are able to compensate for it. In order to address these questions, an individualized longitudinal study was performed on female ICR-CD1 mice analyzing the proliferation as well as the cytokine secretion profile of leukocytes obtained from animals at different ages. The study was performed starting at the adult age, 40 weeks old, and followed each animal individually until its death.

In the present study, it has been found that old mice exhibit a significant increase in the basal proliferation of immune cells, what takes place in the absence of a proliferative stimulus, with respect to when they were younger. In contrast, long-lived mice show basal proliferative levels similar to when they were adults. The high proliferation in the absence of stimulus seen in old mice implies a deregulation of the immune system. Those mice that naturally achieve high longevity are the ones that not only maintained lower levels of basal proliferation and higher levels of proliferation after stimulation during their whole lifetime, but are also those that achieve a better control of the effects of aging on the immune functions. Thus, long-lived mice are those that maintained a lower secretion of pro-inflammatory cytokines and a higher secretion of anti-inflammatory cytokines in unstimulated conditions as well as a higher one upon stimulation when they were old, compared to their age-matched counterparts. This is the first study to demonstrate that the animals reaching high longevity experience immune-senescent changes (to a lesser extent than those which do not reach advanced ages), but they are able to compensate for them by showing optimal levels when they are long-lived.


Linking the Bad Behavior of Senescent Cells with Innate Immune Mechanisms

Senescent cells accumulate in tissues with age, and while they make up a comparatively small fraction of all cells even in late life, they nonetheless cause great harm. These cells actively secrete a potent mix of signals, the senescence-associated secretory phenotype (SASP), that spurs chronic inflammation, degrades extracellular matrix structures, promotes fibrosis, disarrays regenerative processes, and generally changes the behavior of nearby normal cells for the worse. This materially contributes to age-related degeneration and disease. Recently, researchers have linked regulation of the SASP with mechanisms related to the innate immune system, suggesting that there may be opportunities here to sabotage the SASP. There is certainly a faction in the research community who would like to proceed towards therapies on the basis of modulating the SASP without removing senescent cells, but it has to be said that the evidence to date strongly supports the more direct approach of destroying these cells - it is much easier to achieve, and definitively removes all aspects of the SASP, not just a few of them.

Cells in the body or in cultures eventually stop replicating. This phenomenon is called "senescence" and is triggered by shortening of telomeres, oxidative stress or genetic damage to the cells, either acute or simply due to the cell growing "old". Understanding the causes and impact of senescence can give us deep insights into the development of cancer and ageing. When cells senesce, they undergo profound changes, including the secretion of several inflammation-mediating proteins (cytokines, chemokines, extracellular-matrix proteins, growth factors). The production of this "senescence-associated secretory phenotype" controls a number of biological processes such as wound healing and tissue repair, but also tumor formation and some age-related disorders. But although we know how senescence increases the activity of the genes for these proteins, we know very little about how the entire process begins in the first place.

Researchers have now found that senescing cells use a mechanism of the innate immune system to regulate the secretion of inflammation-mediating molecules. The innate immune system includes fast-acting but non-specialized cells (macrophages, neutrophils, mast cells, etc.) that provide the first line of defense against the millions of potential pathogens to which humans are constantly exposed. The innate immune cells use a host of pattern recognition receptors to sense and identify foreign parts of an invading pathogen, such as the DNA of a virus. DNA-sensing is accomplished through a two-receptor system comprising an enzyme called cGAS and an adaptor molecule called STING. Once activated, the cGAS-STING pathway triggers the production of inflammatory proteins that help fight off the pathogen.

Unexpectedly, the researchers now found that senescent cells in the body use the cGAS-STING pathway to regulate and facilitate their secretion of inflammation mediators. But in the context of senescent cells, it is the cell's own DNA that activates cGAS because of defects in the integrity of the nuclear envelope. Examining the relevance of this fundamental mechanism, the study found that the cGAS-controlled secretion of cytokines appears to play a role in various contexts of senescence such oxidative stress, oncogene signaling, and irradiation. The scientists also observed that at least irradiation and oncogene activation exert these actions through cGAS-STING in vivo as well. The study shows that DNA sensing through the cGAS-STING pathway is an important regulator of senescence and the release of inflammatory mediators, and could also serve as surveillance system that protects the organism against neoplastic cells, which opens up new insights for our understanding of the development of cancer. Moreover, since the inflammatory response of senescent cells also promotes ageing, the cGAS-STING pathway could serve as new drug target to tackle age-related diseases.