Attempts to Reverse Aspects of Ovarian Aging

Fertility clinics, just like "anti-aging" clinics, are a lucrative niche industry that has the potential to stop being sketchy and fraud-ridden just as soon as reliable rejuvenation therapies arrive on the scene. Given this, one might view these and a number of other similar industries as potential pools of funding to help bring the first rejuvenation therapies to the clinic. That has to be balanced against the bad publicity attendant with doing business in this part of the market, but considered in the long run, if the therapies work then will even justifiable initial skepticism much matter? The Society for Rescue of Our Elders and Betterhumans trials of senolytic drugs to clear senescent cells are one example of a faction within the highly dubious "anti-aging" marketplace starting to embrace an approach that actually works.

Today's topic is ovarian aging, and the desire to turn back all of the reproductive and metabolic changes that come with it. A variety of interesting efforts on this front have emerged in recent years. You might recall that researchers engineered artificial ovaries and demonstrated them to be fully functional in mice earlier this year, for example. The transplantation of young ovaries into old mice has been demonstrated to extend life and improve health. Over at the SENS Research Foundation you'll find a fairly science-heavy article from a few years back that covers these and other initiatives aimed at postponing menopause.

Here I'll point out news from Inovium Rejuvenation, which seeks to apply the lessons from parabiosis studies to restoring ovarian function in older women. It is an attempt to adjust the balance of signals in the bloodstream towards a more youthful level, something that is also in the process of being trialed by groups such as Alkahest and Ambrosia in the US, though with different goals, different implementations, and measuring different outcomes. My expectation is that likely best plausible outcome, somewhere down the line, is something akin to the results of first generation stem cell transplants - a modestly beneficial override of age-related changes in inflammation, stem cell activity, and so forth. Given the degree of conflicting evidence on parabiosis from the scientific community, unreliable or absent benefits seem equally likely to result, but if you don't try, you don't find out. None of this, of course, is a direct effort to repair the underlying causes of aging. Rather, it is a way to force damaged machinery back into action. As stem cell therapies demonstrate, that can nonetheless produce some degree of benefits, but the damage that causes aging is still there, and that limits the scope of those benefits.

Youthful Blood Reverses Menopause, Aging In Ongoing Clinical Trials

Preliminary results from the world's first clinical trials to reverse menopause and its associated negative health effects in women has shown reversal of menopausal symptoms and hormone restoration to fertile levels. Since July 2017, the California-based Inovium trials have been evaluating the link between a new treatment to restore ovarian function discovered in 2015 by partner clinicians in Athens, Greece. Approximately 10 women and their partners have been selected to move forward in the trial, which will further examine their progress as they begin In-Vitro Fertilization and other strategies for late-life pregnancy. Over 100 additional women have received the treatment in 2017, with over 75% of all women proceeding forward positively towards pregnancy.

The clinical results of the California trials have effectively reproduced the success of preclinical trials conducted in Greece in 2015, where Platelet Rich Plasma (PRP) injections were discovered to rejuvenate the ovaries of menopausal women, restore fertility, and pursue pregnancy. Of more than 60 women who received the treatment preclinically, over 75% now have the option of natural pregnancy or in vitro fertilization, including 9 successful pregnancies. Over 75% have also seen overall hormone levels return to youthful levels. No donor is needed - instead, the patient's own genetic material is used to heal the body. The basic process involves the removal of the patient's own blood plasma, enrichment via centrifuge, and re-injection into the ovaries once elements commonly present in youthful blood have emerged.

As a point of comparison, one might also read the following open access review of the ovarian stem cell niche and the factors leading to its decline with age. The authors argue that immune system and circulatory system function, both of which are certainly line items thought to be beneficially influenced in parabiosis studies, go some way towards determining ovarian function. You can join the dots here to see why research groups might think this is all worth a try, even if approaches intended to change the signaling environment in the bloodstream are really doing nothing to repair the well-described forms of cell and tissue damage that cause aging, and are thus limited in their outcomes.

Ovarian Stem Cell Nests in Reproduction and Ovarian Aging

The fixed primordial follicles pool theory, which monopolized reproductive medicine for more than one hundred years, has been broken by the discovery, successful isolation and establishment of ovarian stem cells. It has brought more hope than ever of increasing the size of primordial follicle pool, improving ovarian function and delaying ovarian senescence. The traditional view holds that stem cell aging contributes to the senility of body and organs. However, in the process of ovarian aging, the main factor leading to the decline of the reproductive function is the aging and degradation of ovarian stem cell nests, rather than the senescence of ovarian germ cells themselves.

Recent studies have found that the immune system and circulatory system are involved in the formation of ovarian germline stem cell niches, as well as regulating the proliferation and differentiation of ovarian germline stem cells through cellular and hormonal signals. Therefore, we can improve ovarian function and delay ovarian aging by improving the immune system and circulatory system, which will provide an updated program for the treatment of premature ovarian failure and infertility.

The Impact of Aging on Skin Biomechanics, Involving Cross-Links and Proteoglycans

The research presented here examines the progression of aging in skin, and its effects on the structural properties of that tissue. There are few surprises here for those familiar with the SENS vision for rejuvenation therapies. The accumulation of cross-links in the extracellular matrix is thought to be a primary cause of loss of elasticity in tissues, and features prominently in this open access paper. Methods of safely breaking persistent cross-links, perhaps resulting from the work on glucosepane carried out at the Spiegel Lab, funded by the SENS Research Foundation, should help to restore elasticity to skin, and more importantly, to blood vessels.

The most visible effects of aging are observed in skin and have been extensively studied for medical and cosmetic purposes. The three skin layers are affected both structurally and functionally. However, aging primary impacts the mechanical integrity of the dermis. At macroscopic scale, the mechanical behavior of aged dermis shows an increased stiffness and a decreased ability to recoil. At lower scales, a complex multi-parameters process eventually results in a decrease of collagen and elastin contents due to an imbalance between matrix proteins synthesis and degradation by matrix metalloproteinases, an increase of collagen cross-linking, a deterioration of proteoglycans and a subsequent loss of water.

Collagens are the main component of the dermis and other connective tissues. Fibril-forming collagens assemble into striated fibrils, the diameter and three-dimensional organization of which are tissue-specific. They form multiprotein networks with other matrix proteins such as the elastin fibers and non-fibrillar matrix (proteoglycans, glycoaminoglycans...) that determine the mechanical behavior of dermis and other collagen-rich tissues. Collagen fibers are usually heterotypic structures. In dermis, they are made of type I, III and V collagens. Type V collagen is a minor component that acts as a regulatory fibril-forming collagen. As such, it plays an important role in the pathogenesis of the classical Ehlers-Danlos (EDS) syndrome. This rare connective tissue disease illustrates the close link between collagen microstructure and tissue mechanics since it is caused by mutations in collagen V genes. EDS patients show a prematurely aged skin, which illustrates the close link between collagen microstructure and skin aging.

The relationship between collagen hierarchical structure and mechanical behavior has been explored using numerical simulations from the molecular scale and constitutive models have been proposed to explain the skin mechanical behavior. Recently, multiphoton microscopy has been used to monitor the reorganization of collagen microstructure during mechanical assays in skin and in various tissues. This allows us to measure simultaneously the microstructural reorganization of the tissue under mechanical stimulation and the mechanical behavior at macroscopic scale, which provides multiscale experimental data not accessible using other techniques.

This study aims at addressing the role of aging on the mechanical multiscale behavior of skin. This issue is addressed in murine skin because of easier availability of matched groups at different ages. We combined traction assays with multiphoton microscopy in ex vivo skin samples from mice aged 15 to 20 months. We compared these data to our previous results obtained in one-month old mice. We studied both wild type (WT) and genetically-modified mice for which collagen V expression in skin has been modulated, inducing modified biomechanical behavior in young mice.

Age-related microstructural changes in the dermis affect collagen fibers as well as the other components of the extracellular matrix. Notably, there is a progressive decrease in collagen, elastin and proteoglycans content, an increase in glycation cross-linking within and between fibers and the matrix proteins become fragmented with little spatial structure. Accordingly, the dermis is thinner, as reported in the literature for human skin and observed in our data for murine skin. The age-related structural changes of the skin have been reported to be largely similar in human and murine skin. Specifically, it has been reported that the collagen content decreases by about 30% between 2 (young) and 22 (old) months in murine skin.

Microstructural data for WT mice showed that the microstructural reorganization upon imposed stretch is the same for young and old mice. This might be surprising considering the many age-related changes in the skin ultrastructure and the quantitative changes of the mechanical parameters. This absence of variation may be explained by the combination of two effects that compensate each other: the increase of cross-linking in old mice impedes the collagen network reorganization, while the decrease of collagen content facilitates this reorganization. The collagen network has a higher level of organization in old mice. This may be attributed to the cumulated effect of skin stretching during lifespan, which is facilitated by the reduced content of collagen and its increased cross-linking. Further, the overall volume of old skin samples decreased upon stretching compared to young mice. This may be explained by the degradation of proteoglycans in old mice, which results in a decreased efficiency to retain water during mechanical stimulation, and therefore a smaller final volume.

In conclusion, our simultaneous observations of the mechanical behavior at macroscopic scale and of the microstructure of dermis are well explained in the framework of our multiscale interpretation of skin mechanics, which seems applicable to both aged and young murine skin. The two main microstructural changes affecting the mechanical properties appear to be the age-induced cross-linking and the degradation of the proteoglycan non-fibrillar matrix, which let the water flow out more easily. All these considerations emphasize the complex role of the microstructure in the mechanical properties. Our findings open the door to future research on human skin to verify whether the above findings obtained in murine skin fully apply to human skin.


Will Rejuvenation of the Thymus Require Rejuvenation of the Lymphatic System?

Some of the decline of the adaptive immune system is caused by the very slow replacement rate of T cells. A slow replacement rate makes the immune system look a lot like it is bounded in size, and within those bounds can be found an ever-increasing number of broken, misconfigured, and malfunctioning cells, their population growing faster than it can be replaced. T cells are created in the bone marrow but mature in the thymus, and the age-related atrophy of the thymus is a primary cause of this slowdown in cell replacement. Thus there is considerable interest in our community in finding ways to restore functional thymic tissue, capable of turning out new T cells at a faster pace. This article takes a look at one of the scientific groups involved in this research.

What if you could experience full health until the very end of your life? Researchers think long-lasting immunity from disease might be possible - if the thymus and the T-cells it produces to fight infection can be brought back to work efficiently. As we age, cells that defend against infection are gradually lost because we stop making them. This is particularly true with T-cells, and the result is often an onslaught of infectious diseases later in life. By rejuvenating the immune system, the researchers are hoping to stop that onslaught.

"T-cells are made in the specialized T-cell factory that sits behind our chest bone, and this is called the thymus. T-cells are critical in orchestrating an immune response. However, by the time we have gone through puberty, the thymus is churning out only one-tenth of the T-cells it made before puberty. What's more, there is evidence that between age 40 and 50, there's another tenfold drop. Down to 1 percent. So, the good news is it's not down to zero. The bad news is you're not producing many T-cells. That's really the earliest manifestation of our aging, the shrinking of the thymus."

However, even if the thymus remained plump and pumped out T-cells at a mad rate, it would be for naught. With age comes the sullying of the lymphatic system, whose job it is to circulate lymph and serve as a highway for T and other immune cells, equipped with vital communication checkpoints. Although T-cells still enter the lymph system in older people, the scant T-cells that are produced can't readily enter the lymph nodes. "Aged lymph nodes aren't able to effectively call in the cells from the outside, so fewer cells arrive. Moreover, when the cells arrive, they don't move inside like they should. Inside the lymph node is a superhighway meshwork, and we have found that this really gets messed up in aging."

So, researchers are formulating a novel plan of attack. "The idea here is that we want to rejuvenate both the thymus and the peripheral lymph organs, so both the factory that makes the cells and sites where the T-cells go to do the real work of defense against infection can once again work together. We feel like we will never get to rejuvenation if we work only on the thymus. If we are successful, we will see an improvement in immune defense and survival. Older adults are still by far the largest population for which infectious diseases still represent a significant risk. Our dream is to bring back the thymus and the T-cells to work the way that they should, particularly if we can fix the lymph nodes. That's not only going to benefit the T-cells but it will benefit the entire immune system. Our lifespan has been extended, but the problem is that for a sizable number of people, they're dealing with chronic diseases the last 15 or 20 years of life, and that is the part I'd like to get rid of. That is the dream of gerontology and the promise of the biology of aging research."


Theorizing that Aging is an Emergent Property of Cellular Competition

Why does aging exist? Why, when we look about the world, can we only find two defensible examples of an immortal species, the hydra and the jellyfish Turritopsis dohrnii? There are a few other species that might be immortal, but the evidence is fairly shaky in near all cases, meaning that it is more of a challenge than is usually the case to show aging, or the data is sparse. These species are probably only negligibly senescent, meaning that they tend to decline rapidly at the end of life and otherwise show few signs of aging up until that point. Lobsters fall into this category, for example. Given that there is exactly one species with good evidence of its immortality - no-one has yet run an equivalent to the rigorous testing of hydra mortality rates in Turritopsis dohrnii - and countless species that clearly age, what are the odds that any given species with poor data is actually immortal? Not so good, I think.

The authors of the paper noted below have an interesting view on why aging is an inevitable outcome of evolutionary processes. To their eyes the declines of aging are an emergent property of competition between classes of cell in multicellular organisms. You might contrast this with the view that aging is a race to the bottom that occurs because environments change, often radically in comparatively short periods of time, and species in which individuals age have a greater ability to adapt to that change than species in which individuals are immortal. Thus aging species out-compete the immortal species in every evolutionary niche over long periods of time. That model has the advantage of predicting that we might see a few immortal species at any given moment, but we should not expect them to last. So while the paper below is thought-provoking, the primary problem I see here is that there is no acknowledgement of the existence of hydra - something of a challenge to a model that presents aging as absolutely inevitable.

In fact, the authors come on very strong with this view of aging as inevitable and beyond our power to defeat in the publicity materials. I have to think that they are quoted out of context and the quotes then assembled by someone who doesn't understand the research, which entirely relates to the evolution of aging, not our ability to intervene in the aging process. How it is we find ourselves stuck in these corroding bodies is a somewhat separate topic from what we choose to do about it - meaning the identification of the best strategies for periodic repair of our failing biochemistry. So I'd say skip the publicity materials, which I think are trying, poorly, to express the idea that there is no way to prevent breakage from occurring in cellular biochemistry, and go straight to the paper. It isn't open access, but the usual way past those barriers works just fine.

It's mathematically impossible to beat aging, scientists say

"Aging is mathematically inevitable - like, seriously inevitable. There's logically, theoretically, mathematically no way out. As you age, most of your cells are ratcheting down and losing function, and they stop growing, as well. But some of your cells are growing like crazy. What we show is that this forms a double bind - a catch-22. If you get rid of those poorly functioning, sluggish cells, then that allows cancer cells to proliferate, and if you get rid of, or slow down, those cancer cells, then that allows sluggish cells to accumulate. So you're stuck between allowing these sluggish cells to accumulate or allowing cancer cells to proliferate, and if you do one you can't do the other. You can't do them both at the same time."

Although human mortality is an undisputed fact of life, the researchers' work presents a mathematical equation that expresses why aging is an "incontrovertible truth and an intrinsic property of being multicellular. People have looked at why aging happens, from the perspective of 'why hasn't natural selection stopped aging yet?' That's the question they ask, and implicitly in that is the idea that such a thing as non-aging is possible, so why haven't we evolved it? We're saying it's not just a question of evolution not doing it; it can't be done by natural selection or by anything else."

"You might be able to slow down aging but you can't stop it. We have a mathematical demonstration of why it's impossible to fix both problems. You can fix one problem but you're stuck with the other one. Things will get worse over time, in one of these two ways or both: Either all of your cells will continue to get more sluggish, or you'll get cancer. And the basic reason is that things break. It doesn't matter how much you try and stop them from breaking, you can't."

Intercellular competition and the inevitability of multicellular aging

Whereas mutation accumulation and antagonistic pleiotropy theory address the role of organismal selection in aging, we ask here whether aging is a fundamental and intrinsic feature of multicellular life. For an organism to avoid aging, it must overcome or mitigate the consequences of heritable changes in somatic cells, the vast majority of which are deleterious, and hence best thought of as "damage." Heritable cellular degradation is a product not just of somatic mutations but also of other changes, such as epigenetic drift and the accumulation of misfolded proteins. In unicellular organisms, competition between cells can weed out deleterious heritable changes, allowing a population to exist indefinitely despite individual degradation. Just as competition between individuals can eliminate deleterious alleles from a unicellular population, competition between cells within a multicellular organism can weed out malfunctioning, slower growing cells within an organism. Therefore, intercellular competition seems to hold the potential for immortality; by continually eliminating damaged cells, a multicellular organism might persist in perpetuity if only selection to do so were somehow strong enough.

Aging in multicellular organisms occurs at both the cellular and intercellular levels. Multicellular organisms, by definition, require a high degree of intercellular cooperation to maintain homeostasis. Often, cellular traits required for producing a viable multicellular phenotype come at a steep cost to individual cells. Conversely, many mutant cells that do not invest in holistic organismal fitness have a selective advantage over cells that do. If intercellular competition occurs, such "cheater" or "defector" cells may proliferate and displace "cooperating" cells, with detrimental consequences for the multicellular organism. Cancer, a leading cause of death in humans at rates that increase with age, is one obvious manifestation of cheater proliferation.

Thus, intercellular competition proves to be a double-edged sword; competition can remove damaged cells, but competition can also allow cheating cells to prosper. Here, we derive a general model of the effect of somatic evolution on aging and examine the behavior of a related model of discrete genotypes in simple numerical cases. Aging is characterized by the dual, but seemingly contradictory, features of loss of cellular vigor and uncontrolled cell growth, and we model the evolution of two corresponding cellular traits. First, we use the term "vigor" to reflect general cellular function or metabolic activity. Second, we use the term "cooperation" to represent investment in traits that are costly to the cell but beneficial for the organism as a whole; one manifestation of loss of cooperation is an increased propensity toward cancer. We show that intercellular competition produces a double bind resulting in inevitably declining organismal vitality with age in multicellular organisms.

Given most organisms' capacity to grow and regenerate, aging does not seem, at first glance, inevitable. Consequently, many have argued that aging is an accident of imperfect selection, where selection fails to purge deleterious, age-related mutations from an otherwise potentially immortal genotype. We have shown that even if selection against aging could be made more powerful, aging would remain an inescapable facet of multicellular life. As our model addresses the role of somatic evolution in aging, it should be seen as complementary, rather than contradictory, to models of aging via evolution by natural selection of multicellular individuals. Our model points to intercellular competition as a key factor in navigating the double bind of cellular degradation and cancer. It suggests that research programs focusing on quantifying the degree of intercellular competition and making comparisons across taxa, among individuals in the same population, among tissues of the same individual, and across developmental time, may be key to understanding the evolution and progress of aging.

No Problem that can Possibly be Produced by Rejuvenation Therapies is Worse than Not Having Rejuvenation Therapies

The Life Extension Advocacy Foundation authors are presently walking through the foundational arguments for pursuing the development of human rejuvenation therapies. This covers the long list of clear benefits to health, wealth, and society; cataloging the terrible cost of aging; pointing out that the most commonly voiced objections veer from the trivial to the ridiculous to the outright and obviously incorrect; and so forth. It is a strange thing that we humans hate to be idle, but at the same time it is in our nature to be very conservative. We cling to the present status quo, no matter how bad it might be, even as we are energetically collaborating to overturn it. You will find no shortage of people who defend the horrific toll in suffering and death caused by aging simply because it and its consequences are familiar. But imagine that aging did not exist: would you find people jumping up to endorse an introduction of the slow and painful death of tens of millions of individuals every year? The gradual, painful, and enormously costly incapacity of hundreds of millions more?

The traditional objections raised against the idea of longer lifespans touch a variety of different topics, but they can all be reduced down to a single, general form: "Rejuvenation biotechnologies would cause a specific problem, so it's best not to go there." Here, we're not going to question whether rejuvenation will cause a certain problem or not; rather, whatever problem we may be talking about, let us assume that it will happen and weigh it against the benefits of the defeat of aging.

To do so, let's keep in mind that aging kills about 100,000 people a day; that is, it accounts for two-thirds of all deaths worldwide. Moreover, it causes an indecent amount of suffering, disability, and debilitation, making the last decades of one's life increasingly miserable. To that, we must add all the problems of an aging society - money and resources spent on pensions and geriatrics with little to no utility, practical and emotional burden on the families of the elderly, too many retired people to be supported by a declining younger population, the lot of them. Let's also not forget that these are virtually everyone's problems. Is the above better than the potential side effects of the defeat of aging and the countermeasures we might thus have to take?

For example, suppose we determined that rejuvenation would cause such an unmanageable population increase that, in order to prevent it, it would be necessary to limit births worldwide, at least until we were able to support a larger population. Is asking all people to become sick and die better than asking those who want children to postpone their parenthood plans?

Another example: imagine that an evil dictator used rejuvenation to prolong his reign of terror by decades. So, on one hand, nobody would suffer and die of aging anymore; on the other hand, people who lived under the dictator would have to endure the dictatorship for longer. Forget for a moment that waiting for a dictator to die of old age isn't the best way to get rid of him; rather, let's reflect on this: would the amount of suffering caused by the dictator to a fraction of the human population be worse than that caused by aging to everyone? Would it be fair to ask the whole world to give up on lifesaving medical technology so that no dictator could ever use it to continue oppressing a minority that could be saved by more effective means anyway?

Let's face it - suffering and death are hardly a solution to anything. Will the rise of rejuvenation biotechnology cause unexpected side effects and challenges? Quite possibly, because it is a disruptive technology, and as such, it has the power to revolutionize our lives. But as for other past disruptive technologies, we'll figure things out as we go.


Werner Syndrome is More Similar to Accelerated Aging than Progeria, but is Nonetheless Not Accelerated Aging

Progeroid syndromes such as progeria and Werner syndrome have at least the superficial appearance of accelerated aging, but are not in fact accelerated aging. They are caused by specific breakages due to genetic mutation, usually in DNA repair mechanisms, that allow a few types of cellular dysfunction and damage to grow over time much more rapidly than is the case in unaffected individuals. Some of these types of damage are thought to be significant in normal aging, but some are clearly not present to any great degree even in very old individuals. What this should tell us is that aging is exactly an accumulation of molecular damage leading to cellular dysfunction. All forms of damage will produce outcomes that can be compared to aging, some more so than others. Whether or not this is useful in aging research depends very much on the specific details in each case.

Werner syndrome (WS) is a segmental progeria. It belongs to a small group of disorders characterized by accelerated aging. WS patients in their 20s and 30s display features similar but not identical to those of normal older individuals. WS is caused by mutations in the WRN gene, a RecQ helicase that protects genome stability by regulating DNA repair pathways and telomeres. Because of its resemblance to normal aging, WS is widely studied in the field of aging, and many consider WS the best example of an accelerated aging syndrome. The recently described hallmarks of aging pathways have been widely considered the key processes affected during aging. Since WS clinical features include many aspects of normal aging, it is not surprising that WRN functions in, or its loss impacts, many of these pathways.

Aging research has enumerated nine hallmarks of aging: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. Patients with WS have defects in DNA repair machinery and show genomic instability. WRN, in association with the telomere-protecting shelterin complex, promotes telomere maintenance, and loss of WRN, as seen in vitro and in patients with WS, results in the rapid decline of telomere length. A progressive increase in DNA methylation is considered an aging biomarker, and, consistent with this, patients with WS display increased epigenetic age. Increased DNA damage accumulation, genomic instability, telomere attrition, and histone methylation are contributing factors for cellular senescence and stem cell exhaustion in WS. Although extensive research is required to sort out the molecular functions of WRN in regulating proteostasis, nutrient sensing, and mitochondria, WS is phenotypically associated with a loss in proteostasis and mitochondrial dysfunction.

Thus many of the hallmarks of aging are found in patients with WS and altered as a direct consequence of WRN loss. Although there is strong evidence for a role for WRN in several of the pathways, others show a weak association and need further investigation. Patients with WS display many aging features, but the initiating pathology for most is still not known.


An Interview with Yuri Deigin of Youthereum Genetics: the Merging of an Initial Coin Offering and Pluripotency Factors

Initial coin offerings (ICOs) are driving most of the light and heat in the blockchain world these days. People are raising enormous sums in cryptocurrencies for ventures with somewhere between little plausibility and ordinary levels of startup plausibility. In many ways it looks a lot like the last years of the internet bubble way back when; there are a lot of parallels. The flows of funding may be driven by some combination of people bypassing Chinese currency controls, early holders of Bitcoins and Ether diversifying their holdings within the blockchain ecosystem, and various large investment concerns whose owners have found they can make a quick buck by flipping blockchain tokens, all of which adds fuel to the fire. As I asked earlier this year, if fairly dubious ventures can pull in tens of millions of dollars doing this, why can't we use this to fund thoughtful, legitimate initiatives in rejuvenation research? The challenge here lies in finding a meaningful use for blockchains and network effects in our world of research and development.

Some groups are forging ahead with that effort. I've mentioned Open Longevity's ICO, in which they seek to fund collaborative human trials of various potential pharmaceutical means to slow aging, but for today the focus is on Youthereum Genetics, a newer venture that also seeks to use an ICO as a mechanism to fund research and development. The Youthereum principals are initially intending to work on a means to deliver pluripotency factors involved in the creation of induced pluripotent stem cells to spur regeneration. A demonstration of this was conducted by a research group and published earlier this year, resulting in health benefits for the progeroid mice often used in early stage aging research. This was somewhat surprising as an outcome: haphazardly inducing cells to become pluripotent in a living organism sounds like a rapid short-cut to cancer.

The next steps will be to try this in normal mice, quantify the most useful dose and delivery method, and continue to watch carefully for evidence of cancer as a side-effect. In the best case this may be a road to a regenerative therapy analogous to stem cell transplants, but that remains to be seen. As in so many areas of research where interesting results may or may not lie ahead, the first question is where the funding for that work will be found. The Youthereum team hope that tapping into the blockchain market is the way to go.

I recently had the chance to chat with Yuri Deigin of Youthereum Genetics, and to ask some questions about his aims. As you can tell he is proceeding from a programmed aging point of view - something that I tend to present as standing in diametric opposition to the more mainstream view of aging as accumulated damage. Possibly oversimplifying, this is the question of whether in aging epigenetic change (a program) causes damage, or whether damage causes epigenetic change (a reaction). A programmed aging point of view leads one to intervene in processes that are, to the accumulated damage point of view, secondary consequences only, and attacking secondary consequences just won't be very effective. We are close to the years in which one side or the other will be definitively proven correct, due to the implementation of specific approaches to the treatment of aging as a medical condition.

Nothing is completely black and white, however, and it is interesting to see the development of areas where theorists from either side of this divide will meet in the middle at approaches to therapies that both will consider potentially useful enough to try, but for different reasons. Some classes of stem cell therapies and efforts to achieve similar effects through changes in signaling or reprogramming cells in situ rather than through delivery of cells are a good example of the type. From a programmed aging point of view, these are levers with which to change epigenetic signaling to more youthful levels, while from an accumulated damage point of view, they could be essentially compensatory in nature, like stem cell therapies, but picking the slack to some degree for native regenerative processes that are hampered by damage.

Why Youthereum Genetics, and why now? Who are you, and how did this organization come to be?

I am a Russian-Canadian transhumanist longevity activist, amateur theoretical biologist, and a biotech entrepreneur. Previously, those areas of my life did not intersect, but in the past few months the stars have aligned to prompt me to finally combine my passion and expertise, and channel them into an undertaking I consider the most important in my life: curing aging. Or - getting off the high horse - at least developing some significant life extension therapies for humans, because at the moment there are none. By "significant" I mean something that can prolong our lives by at least 30%. No therapy outside of caloric restriction has been able to achieve this milestone even in mice - not rapamycin (26%), not metformin (14%), not telomerase (24%), not senolytics (26%) or any other 'geroprotector'. And caloric restriction which holds the record for non-genetic lifespan extension (up to 50% in various rodents) failed to produce anywhere near as spectacular a result in primates. In the two macaque studies conducted on CR, at most a 10% median lifespan increase was observed in females and in some groups CR actually shortened lifespan.

Personally, I believe that the reason behind this inability to put a significant dent in aging in the past 50+ years lies in its programmed nature. Over the years, I have seen plenty of evidence in support of this hypothesis with the most convincing being results from parabiosis and young plasma experiments. I think that aging is ultimately controlled by the hypothalamus, just like all other aspects of ontogenesis. This concept dates back to the 1950s and is described in detail in the works of Dilman, Frolkis and Everitt's. Recent research by Dongsheng Cai and his colleagues provides further evidence for the hypothalamic hypothesis. On the cellular level, aging is most likely both tracked by and executed via epigenetic regulation of gene expression. Several years ago it was first observed that a person's age is highly correlated to his/her epigenetic profile. Later it was recognized that these 'epigenetic clocks' are effective life expectancy predictors, which confirmed that epigenetics is a key component of the aging process. Many organisms were found to have such 'epigenetic clocks' that are highly correlated with both their age and probability of death.

Moreover, Nature knows how to roll back or even completely reset the epigenetic clock. This is done for every new embryo and is most likely the reason why every new animal is born young despite having started as an oocyte cell of the same age as its mother (as mother's oocytes were formed while she herself was still in utero). Finally, experiments with epigenetic rejuvenation which demonstrated that rolling back epigenetics rejuvenates not just individual cells but entire organisms (and prolongs their lifespan) have confirmed that epigenetics is not just a consequence but an important driver or aging. This is where Youthereum Genetics comes in. Based on the recent work of Juan Carlos Izpisua Belmonte's group at Salk, who have shown that periodic induction of OSKM transcription factors can prolong lifespans of progeric mice by up to 50%, we hypothesize that aging can be rolled back by periodic epigenetic rollbacks. Our strategy is aimed at translating this hypothesis into a safe therapy that produces sizable, noticeable rejuvenation in humans.

Why us and why now? In a nutshell, because I grew too tired of waiting for someone else to do it and not seeing anyone step up to the plate. So I put together a team that is capable of designing and overseeing experiments for all the steps involved in first verifying the science behind our hypothesis and then translating it into a therapy should science hold up. The only thing left to do now is a small matter of raising the necessary funding. I am being sarcastic, of course. It is a huge challenge, especially given the amounts required and the associated scientific risks involved. But I am willing to try, even in the face of high odds against.

What is your model for what is going on under the hood in animals transfected with pluripotency factors? Why does it produce benefits?

As I mentioned, I am of the Programmed Aging Witnesses cult. At least that's what some opponents of programmed aging call us. I believe that most if not all forms of various intra- and intercellular damage that we see the body accumulate with age do so because our cells gradually tone down the volume of various damage repair mechanisms. Our cells do so via epigenetic regulation of various genes upon receipt of endocrine signals that originate in the hypothalamus based on circadian rhythms and some sort of an internal clock. We know there is a clock because we can see how finely tuned the timings of various developmental and cyclical processes are - from embryogenesis to puberty to menstrual cycles.

So my belief is that the body has enough capacity for self-repair to function at the level of a 25-year-old for hundreds if not thousands of years, or maybe even longer. If the germ line can do so for billions of years, periodically generating a new organism from scratch, it seems logical to me that just a fraction of those remarkable bodybuilding abilities should be enough to sustain our bodies for much, much longer periods than we see today. So if we find a way to trick our cells into thinking that we are 25, they will function (and get replenished) at the level of a 25 year old regardless of our chronological age. To do so, they would need to have gene expression profiles (epigenetic profiles) typical of 25-year-old humans. And we know from the work of Hannum and Horvath that the epigenetic profiles of 25-year-olds are quite different from profiles of 45- and 65-year-olds.

So when we induce OSKM factors in cells, what I think happens is epigenetic rewinding that is associated with upregulation of various repair mechanisms. It is an empirical fact that induced pluripotent stem cells experience significant rejuvenation that ameliorates virtually all the famous Hallmarks of Aging: telomeres elongate, laminar defects get fixed, mitochondrial function gets restored and so on. There is a great article about this by Vittorio Sebastiano and Tapash Jay Sarkar of Stanford with plenty of details.

That said, one doesn't have to believe in programmed aging to see the potential of epigenetic rejuvenation for life extension purposes. In fact, Aubrey de Grey, who is one of our advisors, despite being a staunch opponent of the programmed hypothesis, also believes epigenetic rollback holds therapeutic promise. In his view, the ability to rejuvenate the aged body by reactivating early-life pathways does not in any way conflict with the idea that aging is unprogrammed and results from the gaps in our anti-aging machinery rather than the presence of actively pro-aging machinery. I would be more than happy to be proven wrong on the underlying mechanisms of epigenetic rejuvenation as long as it provides us with a lifespan extension comparable to that seen in Belmonte's work.

Conversely, why won't this treatment produce an unacceptable level of cancer risk? That is always a concern in this sort of thing.

Absolutely, teratomas are probably the biggest concern of this approach. In fact, before Belmonte showed that there is a Goldilocks zone of OSKM induction that extends lifespan without producing teratomas, cancer risk of this approach was thought to be prohibitive for its translation. Apparently, it isn't. The trick is to roll the cells back ever so slightly to prevent them from de-differentiation, but to do so often enough to prevent (or at least slow down) the accumulation of age-related damage that results from the relentless downregulation of damage repair mechanisms with age.

How does this fit together into your view of aging? What do you expect from this and other efforts in the years ahead? Where would you expect the biggest wins to emerge?

This fits my view of aging like a glove. In fact, the reason I got so excited about Belmonte's results back in February was because before I learned about them, I hypothesized that if we ever learn to roll back epigenetic changes, doing so periodically can provide us with a good enough "hack" to significantly delay aging until we completely decipher its mechanisms and learn to stop them for good. So epigenetic rejuvenation is precisely where I think the biggest gains in life extension could emerge. One other important area that we also plan to explore at Youthereum, albeit in a separate research track, is trying to decode hypothalamic exosome secretions. We think that Dongsheng Cai's latest paper, which showed that 16-months old mice exhibit signs of rejuvenation after a one-time injection with hypothalamic exosomes isolated from cultured hypothalamic neuronal stem cells, is really onto something.

Tell us about your take on how to merge the flow of funds in the blockchain market with the goal of doing something useful in longevity science. So much of what is going on in the ICO space seems a very clumsy effort to bolt one thing, the blockchain, onto another completely unrelated thing that has no logical connection to the blockchain. How are you different?

We are not trying to pretend that we will contribute something to the blockchain infrastructure. We won't, we are a decentralized biotech crowdfunding project that is raising money first and foremost for scientific research. In other words, we are users of the blockchain technology, not its developers. We plan to use it to eliminate any middlemen between us and our funding contributors, and to ensure that all our backers' rights to the therapies we plan to develop are not affected by various governmental red tape - current or future. Those are the two main benefits of decentralization, in our opinion. So we view ICOs as just a more efficient crowdfunding mechanism, even if that makes some blockchain purists cringe. I am not sure why they would cringe, though - by embracing the blockchain paradigm and bringing real-world projects into their realm we are actually validating their technology and greatly expanding its potential user base.

How does Youthereum Genetics differ from Open Longevity, who are trying their own hand at an ICO?

While Mikhail Batin of Open Longevity and I agree that we need more people to do everything possible to develop radical life extension therapies ASAP, we differ on what kinds of interventions could actually produce such life extension. I believe that no therapy that exists today, including any clinically approved drugs, can prolong our lifespans by more than 10%, let alone 30%. So in my view, conducting clinical trials for the Fasting-Mimicking Diet (FMD) or use of statins to see if they have the potential to prolong lifespan is not very useful. Epigenetic rejuvenation, on the other hand, does, in my view, have the potential to prolong our lifespans by over 30% or even much, much greater. That is why I am betting so much of my time and money on it.

If this all goes swimmingly well, and you are buried in funds, with decent animal data on the use of pluripotency factors as a therapy, what next?

Let me try answering this by first describing our research plan. We intend to subdivide it into 3 parallel research tracks: (1) development of an optimal dosing regimen using OSKM factors; (2) search for safer factors of epigenetic rollback that do not lead to complete de-differentiation; (3) creation of the best means of gene delivery, preferably patentable. So our key hypothesis is as follows: in order to reliably rejuvenate the entire body, we need to periodically roll back the epigenetic clock of most cells in the body, if not all cells. Thanks to the work of Belmonte's group, we know that this is possible by delivering OSKM factors (or other transcription factors) into the cell. However, this is a tricky endeavor: roll back too little and you get no sizable effect; roll back too much and you might get cancer, as cells would lose their identity and become pluripotent again. After all, their ability to turn cells back into pluripotent state was the main selection criterion for picking the 4 OSKM factors from the original 24 candidates. So, while OSKM factors are effective and represent a "bird in hand", they are far from ideal for our purposes.

We should strive to find better, safer epigenetic rollback factors; we plan to start by revisiting the remaining 20 factors of Yamanaka's original 24, and also try to use the Oct4 factor alone, since there is evidence that it alone is able to roll back epigenetics and is generally the main "guardian of the epigenetic gates." However, narrowing down the factors is only half of the challenge. Delivering them safely and, ideally, cheaply is the other half. The epigenetic aging program is quite robust even in the face of weekly rollbacks, as demonstrated by Belmonte et al., therefore, obtaining meaningful rejuvenation in humans would most likely require monthly or even weekly induction of epigenetic rollback factors (whether OSKM or otherwise). The most cost-effective way of achieving this would be to integrate a special, normally silent polycistronic cassette containing the genes for the rollback factors into virtually each cell of a patient. Such a cassette would be activated by a unique and normally inert custom agent that would need to be developed separately, and would enable this approach to be patentable. Today such cassettes are activated by, for example, tetracycline or doxycycline. With this approach, the marginal cost of a weekly induction of rejuvenating factors would only be the cost of the induction agent (presumably, a small molecule or a peptide) - comparatively cheap.

In summary, we see the most optimal research plan as a step-by-step, iterative improvement of the already proven approach, the induction of OSKM factors with doxycycline; such a cassette with OSKM factors can be delivered to the body using a lentiviral carrier available on the market today. This will proceed in parallel with the development of an ideal therapy: maximally safe and effective factors activated by a unique, inert, patentable agent. Patentability is crucial for being able to interest Big Pharma in in licensing this therapy upon reaching the IND stage. If the project successfully reaches the IND stage, we believe Big Pharma companies will then be sure to license this therapy to begin clinical studies, first for prevention of atherosclerosis, Alzheimer's disease, diabetes or other age-related indications that anti-aging drugs are using today for regulatory purposes, as aging itself is not yet classified as an indication by the WHO. In a nutshell, that is our plan - get the therapy to the IND stage and then let Big Pharma do what it does best: validate it clinically. We estimate that to get to the IND stage it would take 5-6 years if all goes well.

The Mitochondrial Contribution to Alzheimer's Disease

Like many neurodegenerative conditions, Alzheimer's disease is associated with a general reduction in the function of mitochondria. Since these cellular components are responsible for generating energy store molecules to power cellular processes, and since brain cells require a lot of energy to function, it makes sense to find that declines in mitochondrial function are associated with disorders of the brain. Where does this fit into the chains of cause and consequence in aging, however? What causes global mitochondrial failure throughout cell populations?

Evidence suggests that these general mitochondrial declines are due to failing autophagy, the cellular processes responsible for removing damaged and dysfunctional mitochondria. Equally, it is the case that changes in mitochondrial dynamics, occurring for poorly understood reasons as reaction to other changes and damage in aging cells, appear to hinder autophagy. This is all quite distinct from the consensus on aggregation of damaged and misfolded proteins, amyloid-β and tau, as the primary cause of Alzheimer's disease. Until there are reliable methods to remove and repair one or more of these contributions to the condition, it is hard to do more than theorize on their relative importance.

For three decades, it has been thought that the accumulation of small toxic molecules in the brain, called amyloid beta, or in short, Aβ, is central to the development of Alzheimer's disease (AD). Strong evidence came from studying familial or early-onset forms of AD (EOAD) that affect about five percent of AD patients and have associations with mutations leading to abnormally high levels or abnormal processing of Aβ in the brain. However, the "Aβ hypothesis" has been insufficient to explain the pathological changes in the more common late-onset Alzheimer's disease (LOAD).

"Because late-onset Alzheimer's is a disease of age, many physiologic changes with age may contribute to risk for the disease, including changes in bioenergetics and metabolism. Bioenergetics is the production, usage, and exchange of energy within and between cells or organs, and the environment. It has long been known that bioenergetic changes occur with aging and affect the whole body, but more so the brain, with its high need for energy." It has been less clear what changes in bioenergetics are underlying and which are a consequence of aging and illness.

Researchers analyzed the bioenergetic profiles of skin fibroblasts from LOAD patients and healthy controls, as a function of age and disease. The scientists looked at the two main components that produce energy in cells: glycolysis, which is the mechanism to convert glucose into fuel molecules for consumption by mitochondria, and burning of these fuels in the mitochondria, which use oxygen in a process called oxidative phosphorylation or mitochondrial respiration. The investigators found that LOAD cells exhibited impaired mitochondrial metabolism, with a reduction in molecules that are important in energy production, including nicotinamide adenine dinucleotide (NAD). LOAD fibroblasts also demonstrated a shift in energy production to glycolysis, despite an inability to increase glucose uptake in response to the oxidative stress that impairs their mitochondrial energy production." Because the brain's nerve cells rely almost entirely on mitochondria-derived energy, failure of mitochondrial function, while seen throughout the body, might be particularly detrimental in the brain.


Immune Cells Clear Damage to Assist in Nerve Repair

Immune cells are important in regeneration, carrying out numerous tasks and issuing signals in a complex interaction with other cell types to produce coordinated reconstruction after damage. Researchers here find that neutrophils assist in the task of clearing out debris after injury to the nervous system, in addition to the macrophages already known to carry out this task. This may change the focus of a number of efforts to spur greater regeneration by manipulating the behavior of immune cells.

Immune cells are normally associated with fighting infection but in a new study, scientists have discovered how they also help the nervous system clear debris, clearing the way for nerve regeneration after injury. Researchers have now shown that certain immune cells - neutrophils - can clean up nerve debris, while previous models have attributed nerve cell damage control to other cells entirely. "This finding is quite surprising and raises an important question: do neutrophils play a significant role in nerve disorders?" Neutrophils are one of the most common types of immune cells and known to engulf microorganisms, but they are not normally associated with peripheral nerve damage.

Researchers found damaged nerve cells produce a stream of molecular lures that specifically attract neutrophils to injury sites in mice. Damaged mouse sciatic nerves produced hundreds of times the normal amount of two "chemoattractant" molecules, Cxcl1 and Cxcl2, which attach to the surfaces of neutrophils and draw the immune cells into injured tissue. Once at the injury site, the neutrophils engulf cellular debris caused by the nerve damage, tidying up the area so the cells can repair themselves. Without the cellular clearance mechanism, nerves can't properly regenerate after injury.

Previous studies have pointed to immune cells called macrophages as the primary immune cell responsible for engulfing and breaking down nerve debris. The team was studying mice genetically modified to lack a receptor on the surface of macrophages - CCR2 - that helps macrophages hone in on injury sites. "We expected that the clearance would be dramatically inhibited without the receptor. To our amazement, the clearance was unchanged from that in normal mice. The mystery we to solve was how nerve cell debris is cleared in these mutant animals." The experiments included sorting immune cells found at injury sites by molecules on their cellular surfaces, and many hours looking at mouse cells through the microscope. "Though it turns out that several different cells pick up the slack in the absence of macrophages, it was the neutrophil that emerged as a major contributor to debris removal. We also discovered that when we depleted neutrophils, nerve debris clearance was significantly halted in both normal mice and mice lacking a major population of macrophages." Without neutrophils, nerve cells could not properly clear debris.

The findings could open the door for new therapeutics designed to help repair nerve cells damaged by neurodegenerative disease. Results from the new study suggest immunostimulant molecules that target neutrophils at nerve injury sites might enhance clean-up and promote nerve cell repair. Immunostimulant molecules are often used to treat chronic infections and immunodeficiencies, but additional studies will be needed to determine their specificity and effectiveness in the context of neuropathies.


The Links Between Mitochondrial Dynamics and Progression of Aging are Complex

Every cell contains hundreds of mitochondria, a highly dynamic population of bacteria-like structures responsible for generating the energy store molecule ATP, used to power cellular processes, and that take part in the operation of many of those cellular processes in other ways as well. They are bacteria-like because they evolved from symbiotic bacteria, and still have a remnant of their original DNA. Mitochondria constantly divide, fuse together, are culled by cellular quality control mechanisms, and promiscuously swap their DNA and component parts with one another. Cells even exchange mitochondria. All of this makes mitochondria very challenging to study: they don't stand still to be counted and assessed. Any yet the changes that take place in mitochondria over the course of a lifetime appear very important as a determinant of aging and age-related disease. So difficult or no, the research community must better understand how mitochondria contribute to aging and how that contribution can be turned back.

There are at least two quite distinct classes of process taking place in mitochondria. Firstly there is the damage to mitochondrial DNA that produces dysfunctional mitochondria that can take over cells and make them dysfunctional as well. This involves large deletion mutations, happens as a result of the normal operation of cellular metabolism, and produces a small population of problem cells that pollute the surrounding tissue with oxidized, damaged molecules. This is familiar to those who follow SENS rejuvenation research, as it is here that the recommended intervention takes place: copying mitochondrial DNA into the cell nucleus to provide a backup source of protein machinery to keep the mitochondria from malfunctioning the the harmful way that contributes to the aging process.

The second class of process is much more complex, and involves changes in mitochondrial dynamics of fusion and fission, population size, shape of mitochondria, and energy production. From a SENS point of view, these are secondary and later effects that take place as a consequence of other primary forms of damage and change in aging: cells and their components react, and often in ways that make things worse. All of these mitochondrial changes are comparatively poorly understood as a holistic process, though there are a great many papers that look at thin slices of the issue. Many age-related conditions, particularly neurogenerative conditions as brain cells require a large supply of energy to function correctly, are associated with failing mitochondrial function as a whole: less energy, disrupted participation in cellular activities, and the character of mitochondrial activity changes in numerous other ways.

Some researchers have attempted to classify some of the zoo of possible states of mitochondrial activity in aged tissues by the degree of fusion and fission taking place, by whether mitochondria are becoming fused and large, or staying small in greater numbers. They are also in search of ways to adjust mitochondrial dynamics by dialing up or down the level of fusion or fission. As the research here makes clear that is a very crude starting point when it comes to understanding a complex situation - whether or not changes to fusion and fission map to better or worse outcomes is dependent on other details. I see this as yet more efforts to tinker with the disease state rather than buckling down to strike at the roots of the problem. To make significant progress, tackle the less complex, better understood roots of aging rather than trying to force a partially understood end state into a slightly less worse configuration. This choice of strategy, and the fact that most research groups take the worse approach, is just as apparent in mitochondrial research as it is elsewhere in the field.

Manipulating mitochondrial networks could promote healthy aging

Manipulating mitochondrial networks inside cells - either by dietary restriction or by genetic manipulation that mimics it - may increase lifespan and promote health, according to new research. The study sheds light on the basic biology involved in cells' declining ability to process energy over time, which leads to aging and age-related disease, and how interventions such as periods of fasting might promote healthy aging. Mitochondria - the energy-producing structures in cells - exist in networks that dynamically change shape according to energy demand. Their capacity to do so declines with age, but the impact this has on metabolism and cellular function was previously unclear. In this study, the researchers showed a causal link between dynamic changes in the shapes of mitochondrial networks and longevity.

The scientists used C. elegans (nematode worms), which live just two weeks and thus enable the study of aging in real time in the lab. Mitochondrial networks inside cells typically toggle between fused and fragmented states. The researchers found that restricting the worms' diet, or mimicking dietary restriction through genetic manipulation of an energy-sensing protein called AMP-activated protein kinase (AMPK), maintained the mitochondrial networks in a fused or "youthful" state. In addition, they found that these youthful networks increase lifespan by communicating with organelles called peroxisomes to modulate fat metabolism.

"Low-energy conditions such as dietary restriction and intermittent fasting have previously been shown to promote healthy aging. Understanding why this is the case is a crucial step towards being able to harness the benefits therapeutically. Our work shows how crucial the plasticity of mitochondria networks is for the benefits of fasting. If we lock mitochondria in one state, we completely block the effects of fasting or dietary restriction on longevity."

Dietary Restriction and AMPK Increase Lifespan via Mitochondrial Network and Peroxisome Remodeling

Mitochondrial network remodeling between fused and fragmented states facilitates mitophagy, interaction with other organelles, and metabolic flexibility. Aging is associated with a loss of mitochondrial network homeostasis, but cellular processes causally linking these changes to organismal senescence remain unclear. Here, we show that AMP-activated protein kinase (AMPK) and dietary restriction (DR) promote longevity in C. elegans via maintaining mitochondrial network homeostasis and functional coordination with peroxisomes to increase fatty acid oxidation (FAO).

Inhibiting fusion or fission specifically blocks AMPK- and DR-mediated longevity. Strikingly, however, preserving mitochondrial network homeostasis during aging by co-inhibition of fusion and fission is sufficient itself to increase lifespan, while dynamic network remodeling is required for intermittent fasting-mediated longevity. Finally, we show that increasing lifespan via maintaining mitochondrial network homeostasis requires FAO and peroxisomal function. Together, these data demonstrate that mechanisms that promote mitochondrial homeostasis and plasticity can be targeted to promote healthy aging.

Towards the Transformation of Scar Tissue to Muscle in the Aged Heart

The ability to transform one cell type directly into another has been demonstrated for many combinations of types in the laboratory, at least in principle, if not with the reliability needed to move on to the development of clinical therapies. The types of interest here are the fibroblasts that form scar tissue and the cardiomyocytes of heart muscle. Heart tissue is not very regenerative, and scarring and reduced function follows injury of any sort, especially those arising from the structural failures of age: heart attacks and other forms of cardiovascular disease that can deprive the heart of oxygen and nutrients. With the growing damage of aging it is also the case that regeneration runs awry. The presence of senescent cells and chronic inflammation results in fibrosis, the generation of scar-like collagen structures and raised numbers of fibroblasts rather than the correct maintenance of healthy muscle tissue. What if those fibroblasts could be converted in situ into cardiomyocytes, however?

Reversing scar tissue after a heart attack to create healthy heart muscle: this would be a game-changer in the field of cardiology and regenerative medicine. In the lab, scientists have shown it's possible to change fibroblasts (scar tissue cells) into cardiomyocytes (heart muscle cells), but sorting out the details of how this happens hasn't been easy, and using this kind of approach in clinics or even other basic research projects has proven elusive. Now, researchers have used single cell RNA sequencing technology in combination with mathematical modeling and genetic and chemical approaches to delineate the step-by-step molecular changes that occur during cell fate conversion from fibroblast to cardiomyocyte. The scientists not only successfully reconstructed the routes a single cell could take in this process but also identified underlying molecular pathways and key regulators important for the transformation from one cell type to another.

"We used direct cardiac reprogramming as an example in this study. But the pipelines and methods we've established here can be used in any other reprogramming process, and potentially other unsynchronized and heterogeneous biological processes." When we are babies, embryonic stem cells throughout our bodies gradually change into a variety of highly specialized cell types, such as neurons, blood cells, and heart muscle cells. For a long time, scientists thought these specific cell types were terminal; they could not change again or be reverted back to a state between embryonic and their final differentiated stage. Recent discoveries, though, show it's possible to revert terminally differentiated somatic cells to a pluripotent state - a kind of "master" cell that can self-produce and potentially turn into any kind of cell in the body. Scientists have also figured out how to convert one kind of differentiated somatic cell type into another without detouring through the pluripotent stage or the original progenitor stage.

Direct cardiac reprogramming, a promising approach for cardiac regeneration and disease modeling, involves direct conversion of cardiac non-myocytes into induced cardiomyocytes (iCMs) that closely resemble endogenous CMs. Like any reprogramming process, the many cells that are being reprogrammed don't do so at the same time. "So, at any stage, the cell population always contains unconverted, partially reprogrammed, and fully reprogrammed cells, which makes it difficult to study using traditional approaches. Some of what we found is clinically important. For example, we know that after a heart attack, cardiac fibroblasts around the injured area are immediately activated and become highly proliferative but this proliferative capacity decreases over time. A way to take advantage of the varied cell cycle status of fibroblasts over the progression of a heart attack and its aftermath would certainly broaden the application of cellular reprogramming for patients and optimize outcomes."

The team continued with detailed functional analysis of the top candidate - the splicing factor called Ptbp1. Evidence suggests it as a critical barrier to the acquisition of cardiomyocyte-specific splicing patterns in fibroblasts. The study showed that Ptbp1 depletion promoted the formation of more iCMs. "The new knowledge learned from our mechanistic studies of how a single splicing factor regulates the fate conversion from fibroblast to cardiomyocyte is really a bonus to us. Without the unbiased nature of this approach, we would not gain such fresh, valuable information about the reprogramming process. And that's the beauty of our platform."


The Prospects for Rejuvenation through Targeted Destruction of Senescent Cells

This popular science article covers some of the high points of current work on methods of clearing senescent cells from old tissues, with a focus on the better funded groups - Unity Biotechnology and the research groups involved in that company. So it omits mention of the long years of advocacy prior to 2011, in which the Methuselah Foundation, SENS Research Foundation, and allies called for work on destroying senescent cells based on the compelling evidence for their role in aging that has existed for decades, and were rebuffed. It also omits mention of the other research groups and companies working in the field. This tends to be the way things go, of course - those who are first to raise significant funding tend to be those guiding the presentation of history.

Regardless, this is an enormously promising area of development, and the first rejuvenation therapies to arrive in the clinic in the years ahead will involve some form of senescent cell clearance. Indeed, adventurous individuals could self-experiment with any of the candidate senolytic drugs today, though I think it wiser to wait a few years for the first human trials to report their results. The article plays up indications of variation and typing in senescent cells - that there are tissue-specific differences that will require different approaches for destruction - but I think the concerns here are overblown. Significant health benefits are being achieved in mouse studies even with only partial clearance via one given method, and the variance is nowhere near as large as is the case in cancerous cells.

Although many cells do die on their own, all somatic cells (those other than reproductive ones) that divide have the ability to undergo senescence. But, for a long time, these twilight cells were simply a curiosity. "We were not sure if they were doing something important." Despite self-disabling the ability to replicate, senescent cells stay metabolically active, often continuing to perform basic cellular functions. By the mid-2000s, senescence was chiefly understood as a way of arresting the growth of damaged cells to suppress tumours. Today, researchers continue to study how senescence arises in development and disease. They know that when a cell becomes mutated or injured, it often stops dividing - to avoid passing that damage to daughter cells. Senescent cells have also been identified in the placenta and embryo, where they seem to guide the formation of temporary structures before being cleared out by other cells.

But it wasn't long before researchers discovered the dark side of senescence. In 2008, three research groups revealed that senescent cells excrete a glut of molecules - including cytokines, growth factors and proteases - that affect the function of nearby cells and incite local inflammation. They described this activity as the cell's senescence-associated secretory phenotype, or SASP: hundreds of proteins involved in SASPs. In young, healthy tissue these secretions are probably part of a restorative process, by which damaged cells stimulate repair in nearby tissues and emit a distress signal prompting the immune system to eliminate them. Yet at some point, senescent cells begin to accumulate - a process linked to problems such as osteoarthritis, a chronic inflammation of the joints, and atherosclerosis, a hardening of the arteries. No one is quite sure when or why that happens. It has been suggested that, over time, the immune system stops responding to the cells.

Surprisingly, senescent cells turn out to be slightly different in each tissue. They secrete different cytokines, express different extracellular proteins and use different tactics to avoid death. That incredible variety has made it a challenge for labs to detect and visualize senescent cells. "There is nothing definitive about a senescent cell. Nothing. Period." The lack of universal features makes it hard to take inventory of senescent cells. Researchers have to use a large panel of markers to search for them in tissue, making the work laborious and expensive. A universal marker for senescence would make the job much easier - but researchers know of no specific protein to label, or process to identify. "My money would be on us never finding a senescent-specific marker. I would bet a good bottle of wine on that."

But there's a silver lining to these elusive twilight cells: they might be hard to find, but they're easy to kill. Senescent cells depend on protective mechanisms to survive in their 'undead' state, so researcher began seeking out those mechanisms. They identified six signalling pathways that prevent cell death, which senescent cells activate to survive. Then it was just a matter of finding compounds that would disrupt those pathways. In early 2015, researchers identified the first senolytics: an FDA-approved chemotherapy drug, dasatinib, which eliminates human fat-cell progenitors that have turned senescent; and a plant-derived health-food supplement, quercetin, which targets senescent human endothelial cells, among other cell types. The combination of the two - which work better together than apart - alleviates a range of age-related disorders in mice.

By now, 14 senolytics have been described in the literature, including small molecules, antibodies and a peptide that activates a cell-death pathway and can restore lustrous hair and physical fitness to ageing mice. So far, each senolytic kills a particular flavour of senescent cell. Targeting the different diseases of ageing, therefore, will require multiple types of senolytics. "That's what's going to make this difficult: each senescent cell might have a different way to protect itself, so we'll have to find combinations of drugs to wipe them all out." For all the challenges, senolytic drugs have several attractive qualities. Senescent cells will probably need to be cleared only periodically - say, once a year - to prevent or delay disease. So the drug is around for only a short time. This type of 'hit and run' delivery could reduce the chance of side effects, and people could take the drugs during periods of good health.


A Growing Interest in the Contents of Exosomes in Aging

Exosomes, or extracellular vesicles, are one of the modes by which cells communicate. They are tiny membrane-wrapped packages of signal molecules, constantly secreted and ingested by any population of cells - though note that exosomes are, confusingly, not the same as the larger microvesicles, also membrane-wrapped particles that can carry molecules between cells. Nothing to do with cells is simple or straightforward. In recent years, the falling cost of core biotechnologies has enabled an increasing number of researchers to investigate the contents of exosomes and relate them to specific changes in cellular behavior.

To pick a few examples, exosome signaling is important in the way in which excess fat tissue produces inflammation and metabolic disruption. Researchers are also digging through exosome contents in search of the signals that allow stem cell transplants to produce beneficial effects - it will probably be much more efficient just to deliver the signals themselves. Some groups are adopting an intermediary approach of harvesting and delivering exosomes rather than cells. The specific contents of exosomes definitely change with age, though the details differ for every cell population and process of interest. Senescent cells are one of the root causes of aging, and they produce harmful effects in surrounding cells and tissue structures through inflammatory and other signaling processes - the senescence-associated secretory phenotype. Their exosomes are quite different from those of normal cells, which we might expect to be the case.

The two open access papers I'll point out today touch on the contents of exosomes in a different context, that of neurodegenerative conditions and the age-related decline in cognitive function. These progressive failure modes are all very complex in their biochemistry, largely because the brain is very complex. Simple root causes give rise to end results that are as complex as the surrounding system. Most neurodegenerative conditions have numerous contributing causes and later consequences, tangled up into an unclear mix of layers of only partially understood cause and effect. Changes in cell signaling are certain in there somewhere, along with inflammation, failure of cell maintenance processes, immune system disarray, and growing deposits of uncleared metabolic waste.

Perspective Insights of Exosomes in Neurodegenerative Diseases: A Critical Appraisal

Exosome discovery has exhibited enormous growth over the past three decades. Once known primarily for their role in eliminating excessive cellular proteins and undesirable molecules, exosomes are now known to be required for many physiological processes, such as, the maintenance of normal physiological functions and cell-to-cell communication, and to play important roles in the progression of diseases, such as, cancer and neurodegenerative diseases. Their involvement in neurodegenerative disease progression are attributed to their abilities to transfer biomolecules and pathogenic entities across biological barriers. Furthermore, their abilities to transport proteins and nucleic acids (siRNA, miRNA) have been exploited for the delivery of drugs and other encapsidated biomolecules.

Exosome secretion has been reported for a number of cells in the nervous system. Exosomes have a great effect on cell-to-cell communication, due to: (1) interactions between topical proteins and receptors on target cells; and (2) proteolysis of their cargoes and internalizations of their contents via endocytosis. Furthermore, they allow intercellular communications, via the transport of protein and nucleic acid entities under both normal and diseased states, which suggests exosomes participate in development, cellular function and associated pathologies.

Aggregation of proteins is a hallmark of neurodegenerative diseases, and their accumulations in the central nervous system hinder mitochondrial and proteosomal functions, axonal transport and synaptic transmission and enhance endoplasmic reticulum stress. The ability of exosomes to carry misfolded or aggregated proteins enhances the progression of neurodegenerative diseases. In line with the prion-like spreading hypothesis, their implications in the transmission of infectious particles - prions, amyloid precursor protein, α-synuclein, and superoxide dismutase 1 - between cells in the nervous system are currently being explored.

miRNA in Circulating Microvesicles as Biomarkers for Age-Related Cognitive Decline

Neuroimaging, genetics, and circulating biomarkers are being developed to differentiate normal aging from diseases that affect cognition. While genetic markers may suggest susceptibility to disease, these gene markers are not diagnostic. Similarly, more accurate techniques for identifying pathology, such as positron emission computed tomography, are expensive and may miss early diagnosis, which is critical for treatment. Due to the relative ease of collecting blood, blood based biomarkers could provide a simple and relatively inexpensive means for tracking the progression of cognitive decline and effectiveness of treatments, as well as providing information on mechanism for cognitive impairment. Recent research suggests that non-coding RNAs found in the circulation can act as biomarkers for diseases of aging including cancer, cardiovascular and neurodegenerative disease.

Within the circulation, microRNAs (miRNAs) can be found attached to proteins or in extracellular vesicles, small (50 nm to 1 μm) vesicles of endocytic origin that are released from cells into the extracellular environment. Some (e.g., exosomes) are able to cross membranes (e.g., blood-brain barrier) and can be detected in bodily fluids including serum, urine, and saliva. In this way, microvesicles can provide intercellular and inter-organ communication by delivery of miRNAs to influence transcription and altering genetic processes. Indeed, studies suggest that circulating levels of miRNAs in plasma or in exosomes may be able to identify Alzheimer's disease.

In the current study, we describe miRNAs associated with extracellular microvesicles from plasma as possible biomarkers of cognitive decline during aging. Community dwelling older individuals from the North Florida region were examined for health status and a comprehensive neuropsychological battery, including the Montreal Cognitive Assessment (MoCA), was performed on each participant. A subpopulation (58 females and 39 males) met the criteria for age (60-89) and no evidence of mild cognitive impairment. Despite the stringent criteria for participation, MoCA scores were negatively correlated within the limited age range.

A decrease in MoCA score was associated with increased expression of several miRNAs. The rise in expression of brain selective miRNA could signify conditions in the brain, such as aberrant neural activity, damage, or disease, that result in increased synthesis or release from the brain and a decline in function. In addition, it is possible that highly expressed miRNA are delivered to the brain from the circulation, to influence brain function. The miRNA biomarkers from plasma microvesicle exhibited an expression profile, which was different from that previously described for Alzheimer's disease, suggesting that these biomarkers may be specific to cognitive decline in normal aging.

Implicating Wnt/β-catenin Signaling in Age-Related Hair Graying

Researchers here report their evidence for increased Wnt signaling in hair follicles and skin in older mice to be implicated in the age-related graying of hair. They demonstrate accelerated hair graying through gene therapy to increase Wnt signaling in these cell populations, considering that it produces exhaustion in the cell populations responsible for hair pigmentation. It remains to be seen as to whether the reverse effect can be produced via suppression of this pathway in older animals.

Aging is a physiological process associated with progressive structural and functional declines of tissues and organs. The hair follicle is a mini-organ that undergoes repetitive cyclic regeneration, thus supplying an excellent model for aging-associated disorders. Typical hair follicle aging phenotypes can be observed but not limited to several signs, such as irreversible hair loss, hair thinning and graying.

Regenerative hair cycling process in a single hair follicle consists of three consecutive phases including growth phase (anagen), regression phase (catagen) and resting phase (telogen). Hair stem cell activation during telogen to anagen transition is mainly controlled by two reciprocal out of phases mechanisms. These include Wnt/β-catenin signaling pathway, which shows crucially roles in hair regeneration. The other one is Bmp signaling pathway, which is decreased in competent telogen phase compared to the refractory telogen phase, leading to hair regeneration. Melanocyte stem cells share the same niche with hair follicle stem cells. Progress has been made in unveiling regenerative behaviors and differentiation of melanocytes. Melanocyte stem cells are activated coordinately with hair follicle stem cells during hair regeneration. They migrate out from the bulge niche to the hair matrix region, and differentiate into melanocytes which generate melanin to pigment hairs.

There is increasing evidence showing that many morphogenetic pathways play key roles in regulating melanocytes behaviors. Of these, Wnt signaling functions as an important pathway controlling the patterning of melanocytes and influencing the decisions of melanocyte stem cells differentiation to pigment the hairs. Wnt3a induces melanocyte stem cell differentiation in vivo and in vitro. Exogenous Wnt recruits β-catenin and Lef1 to bind the promoter of microphthalmia-associated transcription factor (MITF), which functions as a key gene that governs fates of melanocyte lineage cells. Previous study shows that one of the visible signs of hair follicle aging is hair loss. However, the mechanism of hair graying as the other obvious sign of hair follicle aging remains further investigation. Whether Wnt signaling acts as a positive or negative regulator in hair follicle aging is unclear.

Therefore, in this study, we first compared the hair graying phenotype in young and adult mice. Since the important role of Wnt signaling in aging of other tissues, we examined periodic expression of β-catenin which is the effector of Wnt signaling pathway, in melanocyte lineage cells during hair cycling. We found that β-catenin expression was significantly increased both at 34 month telogen phase skin and 34 month anagen phase skin in aged mice, when compared to young mice. We observed that β-catenin expression is not only increased in the hair follicles of aged mice, but also increased at the dermal microenvironment. To explore the function of Wnt signaling on melanocyte differentiation, we over expressed Wnt10b through adenovirus-mediated expression in vivo or in vitro, through intracutaneous injection of adenovirus into the young adult skin, or by adding them into melanocyte stem cells, respectively. Our results indicate that Wnt signaling promotes differentiation of melanocyte stem cell, exhaustion of which leads to hair graying during aging.


Patterns of MicroRNA Expression as a Biomarker of Aging

As a complement to the DNA methylation based biomarkers of aging, researchers are also finding that patterns of microRNA levels can serve a similar purpose. These tools offer the potential for a rapid assessment of candidate rejuvenation therapies rather than having to run lengthy life span studies, something that is prohibitively expensive for most research groups even in mice, and entirely out of the question in humans. It is hoped that a generally agreed upon biomarker of aging, a low-cost test that fairly accurately reflects biological age, defined as the burden of cell and tissue damage that causes dysfunction and death, will speed up progress towards the development of rejuvenation treatments. The advent of senescent cell clearance as a viable rejuvenation therapy should greatly help the development and validation of such biomarkers: the two lines of development will support one another.

Human aging is a complex process that has been linked to dysregulation of numerous cellular and molecular processes. Recent studies have revealed that human aging can be characterized by changing patterns of DNA methylation and expression of protein-coding genes. A growing body of research suggests that aging is associated with changes in DNA methylation both genome-wide and at specific C-G dinucleotide (CpG) loci. At the messenger RNA (mRNA) level, a recent meta-analysis of whole-blood gene expression in ~15,000 individuals identified 1497 mRNAs that are differentially expressed in relation to age. An age predictor based on mRNA expression (i.e., mRNA age) highlighted genes involved in mitochondrial, metabolic, and immune function-related pathways as key components of aging processes. The difference between mRNA age and chronological age correlated with many metabolic risk factors including blood pressure, total cholesterol levels, fasting glucose, and body mass index (BMI).

MicroRNAs (miRNAs) are a class of small noncoding RNAs that downregulate protein-coding genes by either cleaving target mRNAs or suppressing translation of mRNAs into proteins. Research in a Caenorhabditis elegans model system revealed changes in miRNA expression in relation to lifespan and longevity. In humans, highly specific miRNA expression patterns are correlated with many age-related diseases including cardiovascular disease and cancer. Recent studies have examined differentially expressed miRNAs in relation to age in whole blood, peripheral blood mononuclear cells (PBMC), and serum. These studies, however, were based on small sample sizes, limiting the power to investigate age-related changes in miRNA expression. We hypothesized, a priori, that it would be possible to create a miRNA signature of age that is predictive of chronological age and that age prediction based on miRNA expression is biologically meaningful and can be used as a biomarker of risk for age-related outcomes including all-cause mortality.

In a previous study, we measured miRNA expression in whole blood from more than 5,000 Framingham Heart Study (FHS) participants. We investigated the heritability of miRNA expression and performed a genome-wide association study (GWAS) of miRNA expression. Our results showed that miRNAs are under strong genetic control. In the present study, we further investigated whole-blood miRNA expression in relation to chronological age in FHS participants. We identified 127 miRNAs that were differentially expressed in relation to chronological age, and performed internal validation by splitting the samples 1:1 into two independent sample sets. An integrative miRNA-mRNA coexpression analysis and miRNA target prediction revealed many age-related pathways underlying age-associated molecular changes. We also defined and evaluated an age predictor based on miRNA expression levels (i.e., miRNA age). Our results indicate that the difference between miRNA age and chronological age is associated with multiple age-related clinical traits including all-cause mortality, coronary heart disease (CHD), hypertension, blood pressure, and glucose levels.


Protein Aggregates of Alzheimer's Disease Observed in Aged Dolphins

What can we learn from the observation that very few other mammalian species exhibit the protein aggregates associated with Alzheimer's disease, the characteristic amyloid-β plaques and tau neurofibrillary tangles? There is debated evidence of amyloid in some primate species other than our own, and a study published earlier this year was the first to claim both amyloid and tau in old chimpanzee brains. Primates do not seem to suffer the widespread death of brain cells that occurs in humans, however, amyloid or no amyloid. In short-lived mammals such as rodents there is little sign of this sort of protein aggregation at all. When researchers are said to study Alzheimer's disease in mice, they are in fact studying one of a number of very artificial biochemistries, genetically engineering lineages given conditions that resemble Alzheimer's in some ways - but these conditions are not actually Alzheimer's. Alongside the enormous complexity of the biochemistry involved, with mapping of the brain and the cell taking place alongside investigation into its failure with age, this artificiality of the mouse models, the fact they are so very different from human Alzheimer's, is one of the reasons why there is a high rate of failure in moving from animal research to human medicine in neurodegenerative research.

In the research noted here, the authors show evidence for dolphins to exhibit both amyloid and tau, making them only the second mammalian species for which this the case. The publicity materials claim it to be the only species, but this is fair enough given that it is only a couple of months since the chimpanzee research was published - that sort of outdated claim is fairly commonplace given that papers can take a year to get through peer review, and months in the final passage to publication. Why humans, dolphins, and chimpanzees, however? Why not mice and horses? This probably ties back in to the question of why longer-lived mammals are longer-lived - what exactly are the biochemical switches and dials involved in this difference? It is of particular interest for our understanding of human evolution because our longevity is comparatively recent, a point of branching from our near primate cousins that may be connected with selection pressures associated with our greater intelligence. Intelligence allows for culture, collaboration, and the Grandmother effect, in which older individuals can help to ensure that their descendants prosper, and thus a longer life is selected for. Should we expect this in dolphins? Data supports the presence of the Grandmother effect in killer whale communities, so it doesn't seem far-fetched.

In the research materials here, it is speculated that some large fraction of the metabolic reactions to calorie restriction, that extend life by up to 40% in mice, have evolved to be switched on all the time in humans and other longer-lived mammals. If the case, this would explain why calorie restriction has only a modest effect on life span in humans - some currently unknown size of benefit that cannot be much larger than a few years, or it would have been noted, measured, and recorded long ago. One counter-argument is that the short term response to calorie restriction in humans is beneficial and looks very similar to that of mice - humans clearly can obtain health benefits through the practice of calorie restriction, and thus perhaps we need to look elsewhere in our biochemistry for an explanation of the sizable difference in outcomes for longevity.

Dolphin brains show signs of Alzheimer's Disease

"It is very rare to find signs of full-blown Alzheimer's Disease in non-human brains. This is the first time anyone has found such clear evidence of the protein plaques and tangles associated with Alzheimer's Disease in the brain of a wild animal." Humans are also almost unique in living long after they are capable of having children; fertility in both men and women declines sharply around the age of 40, but people can go on to live as long as 110 years. Other animals tend to die shortly after the end of their fertile years. Researchers tested the idea that living long after the end of fertility might be linked to Alzheimer's Disease, by studying the brains of another species which can live long after having offspring: dolphins. They found signs of Alzheimer's Disease in the brains of dolphins which had died after washing up ashore on the Spanish coast.

The team analysed 'plaques' of a protein called beta amyloid in the brains of dolphins, as well as tangles of another protein called tau: these plaques and tangles are signatures of Alzheimer's Disease. The team think that humans and dolphins are near-uniquely susceptible to Alzheimer's Disease because of alterations in how the hormone insulin works in these species. Insulin regulates the levels of sugar in the blood, and sets off a complex chemical cascade known as insulin signalling. While alterations in insulin signalling can cause diabetes in people and other mammals, previous scientific work also found that extreme calorie restriction in some animals (e.g. mice and fruit flies) altered insulin signalling - and extended the animals' lifespan by up to three times.

"We think that in humans, the insulin signalling has evolved to work in a way similar to that artificially produced by giving a mouse very few calories. That has the effect of prolonging lifespan beyond the fertile years, but it also leaves us open to diabetes and Alzheimer's Disease. Previous work shows that insulin resistance predicts the development of Alzheimer's Disease in people, and people with diabetes are more likely to develop Alzheimer's. But our study suggests that dolphins and orcas (who also have a long post fertility life span) are similar to humans in many ways; they have an insulin signalling system that makes them an interesting model of diabetes, and now we have shown that dolphin brains show signs of Alzheimer's identical to those seen in people."

Alzheimer's disease in humans and other animals: A consequence of postreproductive life span and longevity rather than aging

Alzheimer's disease and diabetes mellitus are linked by epidemiology, genetics, and molecular pathogenesis. They may also be linked by the remarkable observation that insulin signaling sets the limits on longevity. In worms, flies, and mice, disrupting insulin signaling increases life span leading to speculation that caloric restriction might extend life span in man. It is our contention that man is already a long-lived organism, specifically with a remarkably high postfertility life span, and that it is this that results in the prevalence of Alzheimer's disease and diabetes. We present novel evidence that Dolphin, like man, an animal with exceptional longevity, might be one of the very few natural models of Alzheimer's disease.

Tinkering with Nematode Lifespan Proceeds Apace

There are too many methods of extending life in the nematode worm species Caenorhabditis elegans to mention them all, and too many related research papers arrive each year to note every one. To date all of these approaches involve changing the operation of metabolism in order to slow aging. The paper here is unusual for employing a combination of multiple genetic manipulations, rather than focusing on just one, but is otherwise representative of ongoing efforts to investigate aging by slowing it down in short-lived laboratory species. This sort of work will, I think, have little impact on the development of rejuvenation therapies for human use: those will arise from repairing the forms of molecular damage that causes aging, such as by selectively destroying senescent cells, rather than through alterations in metabolism that gently slow the accumulation of that damage.

Aging is a complex phenomenon influenced by multiple genetic pathways. Aging has been particularly well-studied in C. elegans, where more than 100 genes have been identified that can extend lifespan. Examples of pathways that influence C. elegans lifespan are: 1) control of cellular damage and redox state by mitochondrial activity, 2) protection from bacterial pathogenicity, 3) resistance to cellular stress, 4) caloric restriction and 5) aberrant expression of developmental control genes in old age.

Previous studies have focused on genes and pathways one at a time in order to examine the underlying mechanisms for lifespan extension. Recently, we have investigated the effects of manipulating many of these pathways simultaneously by expressing four transgenes with longevity functions in a transgenic strain. The first longevity transgene was zebrafish ucp2, which has mitochondrial uncoupling activity, a function that is absent from C. elegans. Expression of zebrafish ucp2 extended lifespan by 40% compared to a transgenic control strain. Uncoupling allows protons to leak into mitochondria without producing ATP, thus reducing inner membrane potential. A lower potential attenuates mitochondrial production of free radicals, which reduces free radicals damage accumulation during aging.

The second longevity gene was zebrafish lysozyme, lyz, which has an anti-bacterial function that is not found in C. elegans lysozymes. A strain expressing zebrafish lyz had a lifespan 30% longer than the transgenic control. Worm lifespan is limited by mild pathogenic effects from E. coli, which is used as a food source. Lysozymes degrade the bacterial cell wall and thus are key players against bacterial pathogens. Hence, introduction of a vertebrate lysozyme could extend lifespan by improving innate immunity via reduction of pathogenicity from E. coli.

The third longevity gene was hsf-1, which encodes heat shock transcription factor that induces expression of many stress-resistance genes. Overexpression of hsf-1 extended lifespan 35% compared to the transgenic control. The fourth longevity gene was aakg-2(sta2), which encodes the gamma subunit of AMP activated protein kinase. This is a regulatory signaling molecule that responds to low ATP/AMP ratios and plays a key role in stress response. The sta2 mutation in aakg-2 is a gain-of-function mutation that causes the enzyme to be constitutively active. C. elegans strains expressing aakg-2(sta2) had lifespans that were 45% longer than transgenic controls.

A transgenic strain was generated that expressed all four longevity genes: ucp-2, lyz, hsf-1 and aakg-2(sta2). This strain had a lifespan that was 130% longer than the transgenic control, which is roughly the sum of the effects from each longevity transgene expressed alone. Here, we extend our previous work by manipulating a developmental factor as a fifth component, namely knocking down the HOX co-factor unc-62 (Homothorax) in a strain expressing four longevity genes. RNAi against unc-62 in a wild-type worm has previously been shown to significantly extend lifespan (45%). The mechanism of lifespan extension via unc-62(RNAi) involves reprogramming several developmental pathways. First, unc-62(RNAi) decreases the expression of yolk proteins (vitellogenins) that aggregate in the body cavity in old age, thus reducing protein aggregation in old worms. Second, unc-62(RNAi) results in a broad increase in expression of intestinal genes that typically decrease expression with age, presumably allowing prolonged function in old age.

The quintuply-modified strain has a lifespan that is 160% longer than the transgenic control strain. Additionally, the quintuply-modified strain maintains several physiological markers of aging for a longer time than the transgenic control. Our results support a modular approach as a general scheme to study how multiple pathways interact to achieve extreme longevity.


People Underestimate the Burden of Age-Related Frailty and Disease

It could be argued that one of the reasons why people are willing to put aside consideration of rejuvenation research, and the related prospects for therapies to turn back aging, is that most underestimate the burdens of age. They are young enough to not be personally impacted today, and the older people they know don't tend to be all that open about the challenges, the pain, the suffering. No-one wants to be the walking medical catalog in the conversation, but everyone gets to be just that at some point, when it can't be hidden away any more. From a stoic perspective, if being old isn't that bad, and then you die peacefully, then that isn't such a terrible situation to be in. I think many people have exactly this errant view - that being old isn't that bad from a physical and mental perspective. Yet it is, it is. It is just that older people tend to be reserved about their suffering, popular entertainment features fit and happy older folk, and most younger individuals only have to go through the process of brutal disillusionment once, with the decline of their parents. That still leaves much of a life span in which those illusions can be maintained.

The ill health of old age is a formidable sword of Damocles looming over us all, and when it falls down, it typically does not hit just us; the elderly are certainly the primary victims, but their family are collateral casualties. When people lose their health and independence to aging, their families have to go through the pain of seeing their loved ones becoming more and more fragile, sick, dependent, perhaps even demented. Adding insult to injury, the troubles caused by aging don't stop here, because a sick and dependent person needs looking after. Thus, the family of an elderly person needs to step in themselves to take care of their relative; if this is not possible, a nursing home is likely going to be the only option left.

Personally taking care of a sick elder is no joke. It requires patience, effort, and most of all, time. It's a real challenge, especially so for people who have young kids of their own to look after. Let's also not forget that it is emotionally very taxing. The nursing home option may partly solve the problem, because there, somebody else does the caring for you, but telling your elders that you can't take care of them any more isn't the best feeling in the world, for you or for them. This can be a rather costly solution, too and as much as every last penny spent to take care of a loved one is well spent, a typical family only has so many pennies, and just because they need them for grandpa, it doesn't mean they can conjure money out of thin air.

As things stand, when we're going to be old, our dear ones will be faced with the issues above; however, if a decent rejuvenation platform was in place by then, none of these issues would materialize, because we'd be healthy and independent in spite of our age. We would never be a burden on our dear ones, and the time we'd spend together would be quality time for us and for them. Luckily for me, I'm still very far from that stage of life when all your friends of a lifetime keep dying. I like to think that there would be more than one person grieving for my loss, and I believe that would actually be the case for most of us. If we exclude few, rare scenarios, your friends, and family would probably rather have you alive and well than inside a coffin. Thanks to rejuvenation, your spouse, your children, your grandchildren, and your friends may benefit from your presence, life experience, and persona for a much longer time. This would be a benefit for you as well, because you could live through your 80s, 90s, and who knows how much longer, without having to bury a dear friend a few times a year.


A Concise Overview of Amyloid-β in Alzheimer's Disease

The open access paper noted here is a fairly concise tour through current thinking on the role of amyloid-β in Alzheimer's disease. Amyloids are solid deposits that appear in aged tissues, a few specific proteins that can misfold or become altered in ways that cause them to clump together and precipitate from solution into fibrils and other structures. Either the amyloid itself or, as in the case of amyloid-β, the surrounding biochemistry prompted by its existence causes harm to cells. Since amyloids are created as a side-effect of the normal operation of cellular metabolism, and since they do in fact cause harm, they can be considered one of the root causes of aging. Why they are found in old tissues rather than young tissues is may be primarily a consequences of failing maintenance systems: problems in the drainage or filtration of cerebrospinal fluid; the progressive dysfunction of immune cells responsible for clearing out unwanted metabolic waste; the progressive failure of recycling mechanisms in long-lived cells.

Given this, it is interesting to consider that the high-profile efforts to reduce levels of amyloid-β in Alzheimer's patients, largely through immunotherapies, were one of the earliest forms of significant work on rejuvenation - though not carried out with that intent. It continues to be the most aggressively funded of all such research, and still not with the intent of rejuvenation, though any sufficiently safe and comprehensive treatment could be repurposed for that use. Unfortunately it has proven very challenging to safely remove amyloid-β through the methodologies chosen to date: despite dozens of clinical trials since the turn of the century, only last year was real progress made with aducanumab. Lack of progress breeds a diversity of other approaches, and so despite the central position of amyloid-β in the consensus on how Alzheimer's progresses and causes harm, many competing views of the condition have come into being over the past decade. Some researchers now focus on inflammation, immune dysfunction, and microbial infections. Others focus on tau protein and neurofibrillary tangles, raising the profile of Alzheimer's as a tauopathy. Still more investigate age-related declines in the drainage of cerebrospinal fluid.

Clearance of amyloid-β remains the primary strategy and where most of the funding goes. It does seem fairly clear that Alzheimer's, like most of aging, has multiple contributing causes. Numerous theories of causation other than amyloid-β have a good deal of solid evidence backing them, particularly tau and microbial infection. Given the challenges inherent in analyzing the complexities of the disease, however, it will require success in removing at least one of the causes to make any serious headway in discussions of either (a) the relative size of various contributions, or (b) which are primary causes versus secondary consequences that cause their own problems.

β-Amyloid and the Pathomechanisms of Alzheimer's Disease: A Comprehensive View

Nascent protein chains, emerging from the ribosomes, need to fold properly into unique 3D structures, eventually translocate and then assemble into stable, functionally flexible complexes. In the crowded cellular environment, newly synthesized polypeptide chains are at risk of misfolding, forming stable, toxic aggregates. These species may accumulate in aged animal cells, especially in neurons and can cause cellular damage inducing cell death. Aggregation of specific proteins into protein inclusions and plaques is characteristic for many neurodegenerative diseases (NDDs), including Alzheimer's disease (AD). Molecular pathological classification of neurodegenerative diseases is based on the presence of these pathologically altered, misfolded proteins in the brain as deposits. The combination of proteinopathies is also frequent.

What is the mechanism of formation of toxic protein aggregates in a living cell? Proteins are structurally dynamic and thus constant surveillance of the proteome by integrated networks of chaperones and protein degradation machineries (including several forms of autophagy) are required to maintain protein homeostasis (proteostasis). NDDs are considered mostly as pathologies of disturbed protein homeostasis. The proteostasis network declines during aging, triggering neurodegeneration and other chronic diseases associated with toxic protein aggregation. In both aging and AD there is a general decrease in the capacity of the body to eliminate toxic compounds. In AD, toxic β-amyloid (Aβ) and hyperphosphorylated Tau (pTau) aggregates may interact with subcellular organelles of the neurons, trigger neuronal dysfunction and apoptosis that lead to memory decline and dementia.

Aging per se is the most important factor of AD and several other neurodegenerative diseases, "the neurobiology of aging and AD is walking down the same road". AD could be seen as a "maladaptive interaction between human brain evolution and senescence". Other authors hypothesized that formation of aggregated proteins might be a protective strategy of the aging neurons. There are numerous hypotheses for understanding the pathogenesis of AD, owing to the multifactorial character of the disease. Some of them (disturbance of the cholinergic system; hypoperfusion, hypoxia in the brain; Ca2+-signalization problems; neuroinflammation; mitochondrial dysfunction; chronic endplasmic reticulum stress and protein misfolding; decreased Aβ-clearance, etc.) are not controversial and could be unified into a general broad hypothesis. The common nominator of these hypotheses is the important role of Aβ in the pathogenesis of AD.

The conventional view of AD is that much of the AD-pathology is driven by an increased load of Aβ in the brain of patients ("amyloid hypothesis"). During the last 15 years many therapeutic strategies were based on lowering Aβ in the brain. Up to now, most of the strategies have failed in clinical trials and the relevance of the amyloid hypothesis has often been questioned. Very recent results show that pathophysiological changes begin many years before clinical manifestation of AD and the disease is a multifaceted process. The core of the amyloid hypothesis stays on and novel clinical trial strategies may hold promise.

In the present review article, we summarize the physiological functions of amyloid precursor protein (APP) and the role of amyloid fragments in adult brain. Then we give a short summary on the genetic background of AD, the interaction of Aβ peptides with subcellular organelles, the pathways of Aβ clearance from the brain, the role of neuroinflammation, brain circulation and the blood-brain-barrier (BBB) in the AD pathogenesis. Finally, we discuss very shortly the major trends in drug discovery and the possibilities for prevention and treatment of AD.

Young Endothelial Cells can be Used to Restore Some Degree of Youthful Behavior in Aged Hematopoietic Stem Cells

Stem cells reside in a niche composed of other cell types that provide necessary support. Age-related changes in that niche, the accumulation of damage and reactions to that damage, contribute to stem cell decline in later life. Stem cells become less active, and this and other alterations in behavior produce downstream consequences of various sorts. An example is the tendency of old hematopoietic stem cells, responsible for generating blood and immune cells, to create more myeloid and fewer lymphoid daughter cells. This leads to subtle imbalance and dysfunction in the immune system, an additional burden atop the problems caused by the declining rate at which new immune cells are created.

Finding ways to restore the youthful behavior of hematopoietic stem cells is thus an area of interest for the research community. Scientists here show that engineering a less damaged stem cell niche for these hematopoietic stem cells can reverse declining activity, but not the myleoid bias, suggesting that signals of age-related change arriving from beyond the niche are also influential. Other lines of research suggest that chronic inflammation is an important part of the problem, for example, and inflammatory signals can spread widely through the bloodstream. Nonetheless, the results here suggest that delivery of young niche cells as a therapy could restore some degree of lost immune cell production in aged individuals, strengthening the immune system.

Aging of the hematopoietic system is associated with a decline in adaptive immunity, an increased incidence of anemia, and a predisposition to myeloid neoplasms. Hematopoietic stem cells (HSCs) show an increase in immunophenotypically defined cells with age, a decrease in their long-term reconstitution abilities, and a significant increase in myeloid-biased cell output at the expense of lymphopoiesis. These studies clearly describe the cell-intrinsic HSC alterations that lead to aging-related hematopoietic deficiencies. While the cell-autonomous changes in the HSC that promote aging-related changes in hematopoiesis are more well defined, the contribution of the aged bone marrow (BM) microenvironment in promoting aged hematopoietic phenotypes is poorly understood.

The adult BM microenvironment is a highly specialized cellular niche composed of vascular endothelial cells (ECs) and perivascular stromal constituents that support HSC maintenance and hematopoietic homeostasis. Within the BM hematopoietic microenvironment, the vascular endothelium is indispensable for supporting HSC quiescence, self-renewal, and differentiation into lineage-committed progeny. The aged BM microenvironment has also been shown to influence hematopoietic aging in young HSCs. While ECs are a critical component of the HSC niche, the individual role of aged ECs in the process of hematopoietic aging has not been examined. Here, we explore the idea that aged ECs are sufficient to promote aging of young HSCs and that the infusion of young ECs can be exploited to improve age-related hematopoietic deficiencies.

In this study, we used cultured BM-derived endothelium from young and aged mice to evaluate whether an age-dependent dysregulation of the BM endothelial niche is sufficient to disrupt the homeostatic HSC-supportive microenvironment and drive aging-associated hematopoietic phenotypes. Using an established ex vivo cell culture system, we demonstrated that culturing of young hematopoietic stem and progenitor cells (HSPCs) on aged endothelium inhibited long-term HSC repopulating activity in a competitive transplantation setting and promoted a myeloid bias at the expense of B cell and T cell lymphopoiesis. Moreover, aged HSPCs cultured on young endothelium showed a marked increase in hematopoietic reconstitution.

These results extended to endothelial infusions in young and aged mice, in which aged BM-derived ECs failed to support endogenous hematopoietic recovery following myelosuppressive irradiation and imparted a myeloid bias in young mice; conversely, infusions of young ECs enhanced HSC activity and increased B and T cell output in young and aged animals. Moreover, young EC infusions enhanced aged HSC transplantation (HSCT) and overall survival through protection of the endogenous BM vascular niche. This lays the groundwork for the development of cellular therapies that can serve to enhance hematopoietic recovery in the elderly population following myelosuppressive treatments to ultimately protect patients from severe morbidities and mortality associated with the treatment of hematological disorders.


Longevity Industry Whitepapers from the Aging Analytics Agency

The Longevity International project of the Aging Analytics Agency arises from the Biogerontology Research Foundation / Deep Knowledge Ventures portion of our growing community. The various companies and non-profit initiatives associated with this part of the community - such as In Silico Medicine and the International Aging Research Portfolio - share a focus on data. Those involved are now possessed of quite a lot of information about funding, technologies, and just who is doing what in the research community and market of young biotechnology companies. Thus the Aging Analytics Agency is a consultancy that aims to put to use this domain knowledge of the current field. The intended audience is venture firms and large companies with a newfound interest in medicine to treat aging, currently drawn in to the field by the present flurry of development in senolytics and other areas of rejuvenation biotechnology.

For today, I wanted to point out the Longevity Industry Landscape Overview for 2017, though there are other interesting materials to look through. The perspective of the authors is that of the Hallmarks of Aging rather than the SENS view of the causes of aging, but we can appreciate the points of overlap - the acknowledgement that aging has root cause forms of cell and tissue damage, and that the way forward is to address that damage. If the battle to make progress moves on to a hard-fought, evidence-based argument over which forms of damage are legitimate root causes and how best to tackle them, then that is a big improvement over the present state of affairs, in which the primary issue is the need to convince many more people that aging is a viable target for medicine at all, and that human rejuvenation is a plausible near future goal if we just put more funding into the right sort of existing lines of research.

The term "geroscience" was coined by the US National Institute on Aging, to mean "the field of biological sciences that seeks to understand the role of aging in disease." Of the total $1.6B annual NIA budget, only $183.1M goes to fundamental "Aging Biology", with the majority going to Alzheimer's and particular age-related diseases. The application of fundamental knowledge generated by geroscientists is enabling the development of therapies that prevent and/or reverse the molecular and cellular damage caused by aging. By slowing or reversing the aging process, all age-related diseases can be addressed, leading to a healthy lifespan ("healthspan") extension.

Rejuvenation biotechnology is the translational, clinical, and applied relative of geroscience. This discipline aims to prevent and repair the fundamental damage that causes aging. This damage can include: somatic DNA damage, telomere attrition, transposon-related genomic instability, reduced autophagy and protein turnover, epigenetic drift, stem cell exhaustion, advanced glycation endproducts, and more.

The global population is aging due to longer life (albeit in poor health) and the decision among Westerners to have fewer children. This is a major problem for government healthcare and pension systems. Economists refer to this profound, historically-unprecedented population shift as "The Silver Tsunami." The best way to prevent such a catastrophe for these systems is by slowing or reversing aging itself. Doing so extends the expected healthy lifespan and reduces the number of years each person spends in a socially costly state of chronic ill health and frailty.

The traditional medical model has worked very well for particular acute conditions such as infection and traumatic injury. We are no longer dying from infection, as was the leading cause of death a century ago. Chronic lifestyle and age-related diseases such as cardiovascular disease, cancer, diabetes, stroke, and dementia have become the leading killers in the West. Modern medicine has struggled to address these multifactorial diseases. Given that biological age is the primary risk factor, it makes sense to target the damage that causes aging rather than downstream symptoms.

There are two kinds of drugs: type A, innovative blockbuster, first-in-class, broad market drugs such as statins, antidepressants, and lifestyle drugs; type B, incremental best-in-class or "me too" drugs that offer superior safety or efficacy over existing molecules but do not target a novel biochemical mechanism. Rejuvenation therapy will be of type A. Because everyone ages, anti-aging drugs will have the widest market of any other drug. The disruptive element of rejuvenation biotechnology is that it will displace therapies targeting age-related diseases. Suppose a gene therapy (such as APOE4 or FOXO3A) reverses cardiovascular aging and atherosclerosis. Few will need statin drugs (including atorvastatin, the best selling pharmaceutical in history, generating $125B over 14.5 years for Pfizer). Similarly, why try to selectively kill cancer cells when medicine can repair the DNA damage, quell chronic inflammation ("inflammageing"), and reverse the immune senescence that causes cancer rates to rise so dramatically with age?

Biotechnology and geroscience in particular are on the verge of a Cambrian explosion of breakthrough science that will transform healthcare into an information science capable of improving the human condition more profoundly than even the advent of antibiotics, modern molecular pharmacology, and the Green agricultural revolution. The time-course of this major evolutionary transition and whether we and our loved ones live long enough to benefit from these breakthroughs is dependent upon the choices of the scientific and investment community today.


Why Age? Why Die?

Why age? Why die? The answer today is because we have little choice in the matter. But what if we did have the choice tomorrow? The first real, working rejuvenation therapies, those based on clearance of senescent cells, are under active development in a growing number of companies. Pilot human trials have started at one non-profit, Betterhumans. Funds are flowing into this field of development as the evidence becomes ever more compelling. Adventurous individuals can even, with a little effort, obtain and use some of the early senolytic drug candidates for rational self-experimentation in destroying their own senescent cells. These compounds are not enormously expensive even now, prior to mass-manufacture. Given greater appreciation of this point, given more support, this and a range of other forms of human rejuvenation - approaches based on repair of the forms of cell and tissue damage that cause aging - could be moving much more rapidly towards the goal of reliable clinical treatments that are available to everyone at a reasonable cost.

Given the will to move forward, given popular support, we can give ourselves the choice of whether or not to age. Not quite tomorrow, but within a small number of years. Soon enough to matter. Soon enough that we should be thinking about it today, about how to help make this happen more rapidly, with greater quality of results, with fewer false starts. On this topic, the people behind the popular YouTube channels Kurzgesagt and GCP Grey, with some help from the volunteers of the Life Extension Advocacy Foundation, have put together a couple of videos that are attracting a fair amount of attention. Speaking as a generator of unrelenting walls of text, it is always a pleasure to see quality advocacy work carried out in other mediums. See what you think, and if you happen to know people who are primarily consumers of video rather than the written word, you might point them to these works.

Of the people who give the prospects for the defeat of aging a few moments of thought today, some few will go on to join and support our community tomorrow. Many hands make light work. We don't have to persuade the whole world, just enough people to fund the various necessary lines of rejuvenation research to the point at which they can be proven, picked up by the medical industry, and carried forward by the massive demand for health and working treatments for age-related disease. That is happening for senescent cell clearance, stem cell medicine, and some forms of amyloid clearance today, but there are many other areas that need as much success and attention, and it all needs to move more rapidly than is the case right now. We can do something about that, if we choose to.

A Better Gamma-Secretase Inhibitor for the Treatment of Alzheimer's Disease

Gamma-secretase inhibitors block the formation of the amyloid-β associated with Alzheimer's disease, but to date they are just one more in a long line of failed attempts to produce a therapy for that condition by adjusting the operation of cellular metabolism in the disease state in some way. Existing pharmaceutical gamma-secretase inhibitors act too generally, causing significant disruption of essential mechanisms that far outweighs whatever benefit they might produce. Here, however, researchers claim to have established a much more specific gamma-secretase inhibitor, one that only disrupts the formation of amyloid-β and nothing else. Is this good enough to justify another run at this challenge? Time will tell.

The most common neurodegenerative disorder, Alzheimer's disease is characterized by the buildup of amyloid plaques and neurofibrillary tangles in several brain regions. The leading hypothesis for its pathogenesis is the amyloid cascade - which suggests that the amyloid beta-protein, and particularly the amyloid-beta 42 peptide, initiates the disease process. An imbalance between the production and clearance of amyloid-beta results in the protein's aggregation into larger plaques that lead to the death of brain cells and the cognitive symptoms seen in Alzheimer patients. Several potential treatments have been developed that specifically target amyloid, but none have been effective in halting disease progression.

Amyloid-beta is produced by the cleavage of the larger amyloid precursor protein (APP) by an enzyme called gamma-secretase. Previous research led to the development of gamma-secretase inhibitors that totally block the function of the enzyme, but in clinical trials these drugs produced serious side effects through their effects on the processing of other proteins. As an alternative, researchers first developed the concept of gamma-secretase modulators (GSMs), which change but do not totally suppress the enzyme's activity, back in 2000. More recently reseearchers developed a group of soluble GSMs, one of which - SGSM-36 - appeared to be a promising candidate for clinical development.

In the current study, the researchers showed that three days of treatment with SGSM-36 reduced levels of amyloid-beta 42 in the brains and plasma of a validated mouse model of inherited Alzheimer's without affecting the processing of APP by other enzymes. In cellular models they compared the action of SGSM-36 to that of semagacestat, one of the gamma-secretase inhibitors that failed in clinical trials. While SGSM-36 treatment only reduced levels of the toxic amyloid-beta 40 and 42 peptides, semagacestat reduced all form of amyloid as well as gamma-secretase processing of other proteins, including the important signaling protein Notch, reduction of which may have caused the toxic effects of gamma-secretase inhibitor treatment.

"Genetic, biochemical, molecular biological and pathological evidence all support the hypothesis that excessive accumulation of amyloid-beta - particularly amyloid-beta 42 - is the primary event leading to Alzheimer's related pathology. In our future studies, we will be testing SGSM-36 against similar molecules that may have equal or higher potency in reducing amyloid-beta 42 and further investigating its molecular mechanisms in animal models, with the eventual goal of testing its potential in clinical trials."


Reviewing Cdc42 as a Means to Make Hematopoietic Stem Cells Functionally Young

Hematopoietic stem cells (HSCs), responsible for generating blood and immune cells, decline with age. This is one of the reasons why old immune systems suffer from a low rate of replacement of cells. For some years now, researchers have demonstrated that blocking Cdc42 reverses much of this decline, indicating that stem cell inactivity in the old is as much a matter of response to the aged, dysfunction tissue environment as it is a matter of intrinsic damage, at least in this population. Here, researchers review what is presently known on this topic.

Skin, intestine and blood are composed of short-lived cells that require continuous replenishment by somatic stem cells to maintain tissue homeostasis. Current theory is therefore that especially aging of stem cells that form these tissues will greatly contribute to the decline in tissue function with aging. Identifying mechanisms of stem cell aging and conditions under which aged stem cells become functionally similar to young stem cells might be important first steps towards devising treatments of aging-associated imbalance in tissue homeostasis and tissue regeneration with the ultimate goal of allowing for healthy aging.

Cdc42 belongs to the Rho GTPase family of the Ras superfamily, acting as a binary molecular switch that cycles between a GTP-bound active state and GDP-bound inactive state in response to a variety of extracellular stimuli. A key function of Cdc42 is regulation of elements that structure cells like the actin cytoskeleton or part of the microtubule network, which is believed to be a central mechanism for Cdc42-mediated cell polarization, adhesion and migration. Another important function of Cdc42 is to regulate cell growth signaling. It is becoming clear that the function and signaling pathways regulated by Cdc42 are tissue and cell type-specific, and the general principles of Cdc42 function defined by in vitro methods or from one tissue cell type may or may not apply to another cell type in in vivo situations. This also means that observations for example from fibroblasts (from which most of the information stems) might be informative for designing targeted experiments, but ultimately, in which pathway and function Cdc42 may operate in aged HSCs needs to be stringently dissected in HSCs and can not just be inferred from data obtained in other types of cells or systems.

Cell polarity is well characterized in epithelial cells and neuronal stem cells, but was only recently described to also exist in HSCs. Studies support a critical role of polarity in stem cell maintenance. What might be the role of polarity in stem cells? Polarity can be associated with specialized and compartmentalized functions in HSCs, with migration or with division. A defining feature of stem cells is their ability to maintain a balanced number of stem cells (self-renewal), while at the same time being able to generate specialized progeny (differentiation). Both processes depend on the ability of stem cells to undergo either symmetric or asymmetric divisions, which involve cell polarity.

Supporting a determining role for polarity in stem cell aging is a recent study showing that a loss of proper polarity in aged Drosophila germ-line stem cells correlates with their reduced function. To date, the role of HSC polarity with respect to the mode of HSC division and cell fate potential of daughter cells has not been experimentally tested. Given the established role of Cdc42 in mediating morphologic polarity in many cell types and in regulating HSC differentiation, it has been somewhat logical to postulate that Cdc42 plays a role in coordinating polarity in HSCs.

Genome-wide association studies of longevity in humans linked elevated expression of Cdc42 in hematopoietic cells to increased morbidity and aging. The holy grail of aging research is the question of rejuvenation. Are molecular mechanisms of aging reversible? If elevated Cdc42 activity is causally linked to stem cell aging and apolarity, then reversion of the level to the level found in young HSCs might result in "younger" HSCs. Aged HSCs, in which Cdc42 activity level was, via pharmacological inhibition, reduced to the level found in young mice, presented functionally and upon transplantation almost identically to young HCS. This suggests that Cdc42 activity might represent a novel target to rejuvenate aged HSCs via altering stem cell polarity.


Patient Paid Clinical Studies are a Good Plan for Rejuvenation Therapies

There are great many people willing to rain fire and brimstone upon the merest mention of clinical studies in which the patient pays the costs. They emerge whenever any group runs such a study, or whenever an initiative earnestly proposes greater adoption of this structure of trial for medical procedures. At root, there is a sizable fraction of the population that seems very hostile to the idea that patients be allowed to choose their own risks, and we see this hostility whenever some loosening or adjustment of regulation is proposed. Petty authoritarianism, yes, but to the degree that it shuts down responsible experimentation and progress in medicine, and slows the pace of development as a consequence, it is just as harmful as the real thing.

A primary complaint about the patient paid structure is that it is impractical to conduct blind studies or use placebo treatments in a control group, as people tend to want to get what they paid for. This greatly reduces the ability of a study to assess the presence or absence of effects that are small, intermittent, or vary widely between patients due to as-yet unknown factors. If you are looking for small and unreliable effects, and sadly this is pretty much the case for most modern medicine for the treatment of age-related disease, then this is a fair criticism. You should not be trying to use this sort of trial structure in such a scenario.

However, when it comes to rejuvenation therapies we are not interested in small and unreliable effects. Small and unreliable is the same as failure. The SENS rejuvenation research programs, and any other initiative to repair the causes of aging, is aiming for large and reliable effects. The expectation is certainly there for success in addressing any of the molecular damage at the root of aging to produce reliably beneficial outcomes in patients. We all age for the same reasons, and a beneficial therapy in one individual should be beneficial in every individual of much the same age group. But people are used to the marginal effectiveness of present day medicine, the quest for tiny, incremental, unreliable gains, and that steers their expectations regarding the appropriate way to proceed.

When it comes to placebo treatments, it is arguably the case that some types of patient paid rejuvenation therapy trial could be structured to include them. Consider senolytic treaments that clear senescent cells, for example. One could envisage a trial that involves two treatments two weeks apart. One is a placebo. After each treatment, metrics are assessed. In mice, beneficial changes following elimination of senescent cells occur quite rapidly, as the senescence-associated secretory phenotype is cleared out. There will be measures of health status in humans that can be checked a few days or a few weeks later. So in general, there are often ways to proceed with a placebo for short-term studies and short-term measures.

Yes, for longer-term patient paid studies the use of a placebo control group just isn't practical. Again, however, the point of the exercise is the detection or confirmation of reliable, large effects. It is perfectly viable to use the rest of the population as your control group. If a senolytic therapy cuts back all sorts of measures of metabolic age quite quickly, to a degree that can only be achieved via other methods over a long period of time, if at all, then it is hard to reject that out of hand just because there was no control group of study participants. Based on the results in mice to date, and what is known of cellular senescence in humans, one would expect the first drug or other therapy to replicate the same degree of cell clearance in humans to be so very evidently beneficial that attempts to run blind studies with control group will be pointless - they will add little.

The response from the more conservative end of the scientific community following a patient paid study that shows significant benefits should be to pull in funds and interest to run their own more structured and careful studies to better quantify and improve upon the results. Publicity from the patient paid study will help them to do that, breaking through the reluctance that seems to characterize much of the industry. The patient paid structure is a way to bring in the necessary funding to carry out pilot studies in the absence of funding bodies within the existing institutions willing to do that. Given the history of the development of senescent cell clearance as a field of medicine - the long years in which it was ignored despite the compelling evidence, the struggle to fund the landmark studies in mice that proved that removing senescent cells could reverse aging - we should all be very skeptical that existing institutions will ever fund worthy projects in rejuvenation research if left to their own devices. They need to be kicked into action by outside efforts and outside funding, as they are otherwise happy to drift along performing marginal work.

If we want radical change to take place in the research community, if we want to see more work on human rejuvenation based on the SENS vision of repair therapies that can turn back aging, then patient paid studies are an important tool in the toolkit. Money doesn't grow on trees, and there are costs involved in getting the job done. Patient paid studies are one of the ways to overcome that hurdle.

Why Pursue the Development of Rejuvenation Therapies?

Why pursue the development of rejuvenation therapies? What do I get out of it? The answer to that question - health! - is self-evident to those of us who have been thinking about this for a while, but a fair amount of advocacy for any cause is a matter of explaining what is obvious to the advocate, but not to someone unfamiliar with the idea. Sometimes it is hard to see one's own blind spots, and especially so when it comes to long exposure to a subject: we forget what it was like not to know. Given that, I think an overview of the point of developing rejuvenation therapies, discussing what an individual stands to gain, is a good thing to have in the toolkit.

I'm sure you've noticed that the Life Extension Advocacy Foundation has been shouting from the rooftops for quite a while that rejuvenation biotechnologies need to happen, and we're doing our best to make them happen as soon as possible. The job isn't easy; the fact that numerous people still raise concerns about the idea doesn't make it any easier, and we invest part of our time duly addressing those concerns. But the discussion about what might go wrong or how to prevent this or that hypothetical problem might draw attention away from another, possibly even more important question: why do we strive to make rejuvenation a reality? There's not much point in doing something if it yields no benefits, especially if that something requires as much hard work as this cause does; so, what are the expected benefits of rejuvenation?

Health: rejuvenation, we have said time and again, is pretty much all about health. The causal link between biological aging and pathologies is well established, and even when we account for the few elderly who are exceptionally healthy for their age, we're left with the obvious fact that the older you are, the sicker you are - and even the aforementioned exceptions aren't in the best of shape. To the best of my knowledge, the number of people who actively wish to be sick at some point tends to be fairly small; so, when you think that a truly comprehensive rejuvenation platform would allow people to maintain youthful health irrespective of their age, the health benefits of rejuvenation become crystal clear.

Independence: frailty, failing senses, weakness, and diseases aren't good friends of independence, but they are good friends of old age. That's why nursing homes exist in the first place - to take care of elderly people who are no longer independent. Again, even the few exceptional cases who manage on their own until death don't have it easy. Having people doing things for you can be nice in small doses, but having to have people doing things for you, not so much. Rejuvenation would eliminate the health issues that make the elderly dependent on others.

Longevity: as odd as it may sound, longevity is really just a 'side effect' of health, because you can't be healthy and dead. The longer you're healthy enough to be alive, the longer you'll live. Since rejuvenation would keep you in a state of youthful health, the obvious consequence is that you'd live longer. How much longer exactly is hard to say, but as long as you're healthy enough to enjoy life, it's safe to say that longevity would be a benefit; you'd have more time and energy to dedicate to what you love doing, and you could keep learning and growing as a person for an indefinitely long time.

Ultimately, all of these perks can be summarised into one: choice. If we had fully working rejuvenation therapies available and were thus able to keep ourselves always perfectly healthy, regardless of our age, we could choose whether we wanted to use these therapies or not. Those who wish a longer, healthier life could avail themselves of the opportunity and escape aging for as long as they wanted; those who prefer to age and bow out the traditional way could just as easily not use the therapies. Rejuvenation would give us an extra option we currently don't have; everyone is forced to face the burden of aging and eventually die of it, for the moment. Being able to choose what we wish for ourselves is one of the most fundamental human rights and an obvious, unquestionable benefit.


Cell Cycle Activation Increases Cardiomyocyte Replication to Repair Heart Damage

Mammalian heart tissue is not very regenerative in the normal course of events. The cells are slow to divide and make up their numbers, even in response to damage, whether that caused by a heart attack or other structural failure in aging tissues, or the more minor wear and tear of everyday life. Given this, one of the present themes in regenerative research is to find ways to spur greater rates of cell division in heart tissue, a compensatory strategy, but possibly beneficial enough to be worth trying. Approaches such as blocking the Hippo pathway, or delivering microRNAs that influence some of the same machinery look promising in animal studies. Here, researchers outline another approach to trigger the cell cycle and thus increase the pace at which heart cells divide, but with a focus on achieving this goal in transplanted cells rather than native cells.

Biomedical engineers report a significant advance in efforts to repair a damaged heart after a heart attack, using grafted heart-muscle cells to create a repair patch. The key was overexpressing a gene that activates the cell-cycle of the grafted muscle cells, so they grow and divide more than control grafted cells. Up to now, an extremely low amount of engraftment of cardiomyocytes has been a stumbling block in hopes to use grafted cells to repair hearts after a heart attack. Without the successful repair that a graft could potentially offer, the damaged heart is prone to later heart failure and patient death.

In experiments in a mouse model, researchers showed that gene overexpression of the cell-cycle activator CCND2 increased the proliferation of grafted cardiomyocytes. This led to increased remuscularization of the heart at the dead-tissue site of the heart attack, a larger graft size, improved cardiac function and decreased size of the dead tissue, or infarct. Besides regenerating muscle, the grafted cells also increased new blood vessel formation at the border zone of the infarct, apparently through increased activation of the paracrine mechanism. The team used cardiomyocytes that were derived from human induced pluripotent stem cells, as they work toward a goal of eventual clinical treatment for human heart attack patients.

Researchers first showed that overexpression of CCND2 in the human induced pluripotent stem cells-derived cardiomyocytes, or hiPSC-CMs, increased the proportion of cells that exhibited markers for the S and M phases of the cell-cycle, and for cytokinesis, as measured in cell culture. When they injected overexpressing hiPSC-CMs into the infarct region and the border of the infarct in the mouse model, the left ventricle ejection fraction was significantly greater at week four and the infarct size was significantly smaller, as compared with mice receiving normal hiPSC-CMs that did not overexpress CCND2. Both treatments were improvements as compared with untreated mice. Overexpression also led to an increased number of engrafted hiPSC-CMs, as measured by bioluminescence and human cell markers.


Senescent T Cells Generate the Same Damaging Secretions as Other Senescent Cells

The immune system runs awry with age in a number of overlapping ways. The adaptive component of the immune system, made of B cell and T cell populations that adapt to store information about the pathogens they encounter, in particular suffers from forms of misconfiguration and exhaustion. Too many cells become devoted to useless tasks, such as the continually expanding and pointless battle against cytomegalovirus. Too much activity against pathogens produces large numbers of exhausted T cells and anergic T cells, incapable of responding aggressively when reacting to new threats, and not replaced rapidly enough with fresh T cells. Aging is accompanied by a diminished capacity to generate new T cells; this limit squeezes down from the top, while the failure and overspecialization of T cells squeezes up from the bottom. The immune system becomes ever less capable.

Because the T cell response to invaders involves replication, the rapid creation of a suitably equipped army to fight whatever the current war might be, there will always be some degree of cellular senescence in T cells, just as in all replicating cell types in the body. Cellular senescence is one of the full stops at the end of a normal cell's life span: it can only divide so many times before its telomeres become short, it hits the Hayflick limit, and either self-destructs or becomes senescent. Senescent cells near all go on to self-destruct a little later, or are destroyed by portions of the immune system dedicated to that purpose. Senescence can also be triggered by DNA damage resulting from a toxic environment, other forms of severe cellular stress, or the signals of nearby senescent cells. This serves to suppress the risk of cancer by removing those cells most likely to gain the combination of mutations needed to run amok. Senescent cells also have some transient, beneficial activities: they are involved in wound healing and embryonic development, again being destroyed after their task is complete.

Unfortunately some senescent cells linger for the long term, evading destruction. I say unfortunately because senescent cells generate a potent mix of inflammatory and other signals, the senescence-associated secretory phenotype (SASP). This disrupts regenerative processes, corrodes nearby tissue structures, and spurs the chronic inflammation that drives so many of the aspects of aging. While only a few percent of all cells have become senescent by the time old age rolls around, that is more than enough to have caused a significant fraction of the medical conditions of degenerative aging. Researchers have shown that senescent cells are one of the direct significant contributing causes of a wide range of issues: the ultimately lethal fibrosis that occurs in many organs; osteoarthritis; atherosclerosis; and more.

In the research noted here, the authors show that senescent T cells have essentially the same SASP as other forms of senescent cells investigated in recent years. This means that they will be just as harmful to health, a cause of aging given sufficient numbers. It is something of a debated question as to how much of T cell dysfunction with age is a matter of anergy, exhaustion, or senescence, and so also a question as to how many of these cells there are. If the numbers are significant, their presence also means that efforts to selectively remove senescent cells by provoking them into apoptosis, or by identifying their specific internal chemistry, should be expected to improve immune function alongside the other benefits shown to date in animal studies. Clearing out broken, dysfunctional T cells will free up space in the immune system and trigger their replacement. That will happen slowly in old people, given the limited replacement rate, but that too can be improved with suitable cell therapies - delivering large numbers of patient-matched immune cells is well within the present capacities of the biotechnology industry, just another of a fair number of potential treatments that have yet to be pushed through the regulatory system. Too many possibilities, too few researchers, and too high a regulatory barrier to entry.

Human CD8+ EMRA T cells display a senescence-associated secretory phenotype regulated by p38 MAPK

Immune senescence results from defects in T-cell immunity and is also characterized by a low-grade chronic inflammatory state. Little is known about the source of the inflammation that fuels most age-related diseases; however, it may derive from an age-related decline in homoeostatic immune function, resistance to endogenous microbes or senescent cells. The senescent phenotype is not just proliferative arrest; rather, it is a widespread change in protein expression and secretion, including pro-inflammatory cytokines, chemokines, growth factors and proteases, termed the senescence-associated secretory phenotype or SASP. Consequently, senescent cells can alter the tissue microenvironment and affect neighbouring cells through paracrine signalling.

The SASP was originally thought to result from persistent activation of the DNA damage response; however, it is now known to be regulated by p38 MAPK, which was shown to be both necessary and sufficient for its development in fibroblasts. The chronic and sustained activation of p38 MAPK differs substantially from the response to acute stress and was found to follow the kinetics of SASP development. Furthermore, siRNA interference of p38 MAPK was shown to significantly reduce the secreted levels of most SASP factors. To date, the SASP has predominantly been characterized in fibroblast cell culture models or aged mice, with very few reports of a SASP being found in the human immune system with either age or differentiation.

Senescent CD8+ T cells are found within the CD27-CD28- population, and these highly differentiated T cells can be further divided using CD45RA. T cells that re-express CD45RA within this subset have multiple characteristics of senescence, including a low proliferative activity, high levels of DNA damage and the loss of telomerase activity. We have also shown that p38 MAPK signalling, which is increased in highly differentiated CD8+ T cells, is involved in the loss of telomerase activity and proliferative capacity and that blockade of p38 MAPK activity with a specific small-molecule inhibitor can restore both proliferation and telomerase activity in these cells. However, surprisingly the CD45RA-re-expressing senescent T cells do not have critically short telomeres, suggesting that senescence in these cells may be induced by other mechanisms including DNA damage by increased reactive oxygen species production.

In this study, we demonstrate that irrespective of the derivation of CD8+ CD45RA+CD27- T cells, these primed cells exhibit a unique highly inflammatory secretory profile characteristic of the SASP, and we also provide evidence that ADAM28 can be used as a functional marker of senescence in CD8+ T cells. Furthermore, we show that the secretory phenotype in CD8+ CD45RA+CD27- T cells is controlled through p38 MAPK signalling, which contributes to age-associated inflammation.

KLF4 Involved in Autophagy and Age-Related Vascular Dysfunction

There are any number of specific proteins associated with the progression of aging and its dysfunctions in one way or another. The overwhelming majority are not directly involved in the fundamental molecular damage that causes aging, but rather in the secondary consequences and reactions to that damage. It is therefore the case that they are poor targets for efforts to treat aging, because trying to manipulate the dysfunctional state of metabolism is a poor substitute for fixing the root cause damage that leads to that dysfunction. The research here is an example of the type, and the sort of investigations that result.

The maintenance of cellular and organismal homeostasis determines the progress of aging. On a cellular level, homeostasis is maintained, in part, through macroautophagy (hereafter referred to as autophagy), a conserved mechanism by which a cell achieves multiple goals, including clearance of misfolded proteins and organelle turnover with subsequent recycling of degraded constituents. As cells age, their ability to perform these functions declines. This likely leads to an unsustainable accumulation of protein aggregates, which ultimately present an obstacle to cellular survival. Indeed, studies of the distinct signaling networks in C. elegans that modulate lifespan have provided evidence of a central role for autophagy in many known longevity paradigms.

Thus loss of protein and organelle quality control secondary to reduced autophagy is a hallmark of aging. However, the physiologic and molecular regulation of autophagy in long-lived organisms remains incompletely understood. Here we show that the Kruppel-like family of transcription factors are important regulators of autophagy and healthspan in C. elegans, and also modulate mammalian vascular age-associated phenotypes.

Kruppel-like family of transcription factor deficiency attenuates autophagy and lifespan extension across mechanistically distinct longevity nematode models. Conversely, Kruppel-like family of transcription factor overexpression extends nematode lifespan in an autophagy-dependent manner. Furthermore, we show the mammalian vascular factor Kruppel-like family of transcription factor 4 (KLF4) functions to regulate autophagy in vascular endothelial cells and modulate blood vessel aging in mice. KLF4 expression also decreases with age in human vascular endothelium. Thus, Kruppel-like family of transcription factors constitute a transcriptional regulatory point for the modulation of autophagy and longevity in C. elegans with conserved effects in the murine vasculature and potential implications for mammalian vascular aging.


Parabiosis Restores Some Kidney Function in Aged Animals

In parabiosis studies, a young and old animal have their circulatory systems linked. This is shown to improve measures of aging in the old animal, such as regenerative capacity, stem cell activity, and so forth. There is considerable debate over the mechanisms involved, with the current balance of evidence favoring a dilution of harmful factors and signals present in old blood and tissues rather than a delivery of beneficial factors and signals present in young blood.

In the research reported here, the authors examine the effects of parabiosis on the function of aged kidneys. It is too early to say what this will add to the discussion of specific mechanisms, but speculation is certainly possible. Even given the consensus, it has to be said that the data looks a lot one might expect to see if young immune cells are coming in and doing a better job of reducing the senescent cell burden in an aged kidney than the native, old immune system is capable of achieving. Yet it is also possible that simply altering the balance of factors in the surrounding environment spurs more of these unwanted and harmful cells to self-destruct on their own, given that they are already primed for apoptosis.

Whether changes in internal body environment affect kidney aging remains unclear. Specifically, it is unknown whether transplanted kidneys from older donors recover from tissue damage after placement in younger recipients. In this study, a parabiosis animal model was established to investigate the effects of a young internal body environment on aged kidneys.

The animals were divided into six groups: young (Ycon) and old (Ocon) control groups, isochronic youth-youth group (Y-IP), elderly-elderly group (O-IP) and heterochronic youth (Y-HP) elderly (O-HP) group. After parabiosis, tubule and interstitial tissue scores in the O-HP group were significantly lower than in the Ocon and O-IP groups. The expression of aging-related protein p16 and senescence-associated β-galactosidase in the O-HP group was significantly reduced compared with the Ocon and O-IP groups. Autophagy factor Atg5 and LC3BII were significantly upregulated, while the expression of the autophagic degradation marker (P62) was significantly downregulated in the O-HP group compared with the Ocon and O-IP groups.

With the same comparison, the positive cells of TUNEL staining and the expression of inflammatory cytokines IL-6 and IL-1β were significantly reduced, while the total/cleaved caspase-3 and total/pNF-κB were significantly increased in the O-HP group. The results demonstrated that a young blood environment significantly reduces kidney aging. These findings provide new evidence supporting an increase in the upper age limit for human kidney transplantation donors.


Mesenchymal Stem Cell Transplants Trialed as a Therapy for Age-Related Frailty

At least one group is running trials of stem cell transplants as a potential treatment for age-related frailty syndrome: the scope of the possible in the near term is to find way to incrementally improve the condition, not produce a sizable reversal, but that is an improvement over the current situation, given that there is no effective treatment. The closest thing to a standardized, proven, reliable class of stem cell therapies involves the use of mesenchymal stem cells, sourced from a patient, or from lines of cells grown and engineered for transplantation with minimal risk. The primary outcome of mesenchymal stem cell therapies, or at least the reliable outcome, is a reduction in the systemic, chronic inflammation that accompanies old age. While it is entirely possible that other mechanisms are at work, the cells typically don't last long following transplantation, and thus it is the brief signaling changes that must produce benefits that can last for months or longer.

Chronic inflammation is a major problem in aging. It drives progression of most of the age-related conditions, and high levels of inflammation are certainly considered to be a major component of frailty syndrome in the old. In the context of a general treatment for frailty based on reductions in inflammation, the focus is less on the acceleration of specific age-related conditions over time, however, and more on the immediate consequences of constant high levels of inflammation for cell biochemistry, pain, cognitive function, joint function, regeneration, and tissue maintenance. Many aspects of age-related dysfunction are to some degree being actively maintained in their current impacted state by the presence of inflammation - take away that inflammation, and the problems subside a little, back to the lower level of harm and loss expected due to accumulated cell and tissue damage.

In recent years, it has become clear that chronic inflammation, as opposed to the normal short-term inflammation resulting from injury or infection, disrupts the finely tuned dance carried out between tissue and immune system needed for regeneration. This is an emerging theme in the investigation of how senescent cells cause aging, for example, as these unwanted cells are potent sources of inflammatory signaling. So if we see unreliable or marginal benefits from stem cell therapies that look like enhanced regeneration, it might well be that this is at root a short-term reduction in the age-related disruption of tissue maintenance - perhaps enough to allow a little reconstruction to take place in some patients. This is speculation, of course, and the cellular biochemistry is challenging to investigate; we should probably expect a first generation of moderately reliable therapies in advance of complete understanding of their mechanisms. Here is another point to consider on this topic: if the inflammation model of benefits is correct, then clearance of senescent cells should be at least as good a treatment for frailty as mesenchymal stem cell transplant, and probably better and more lasting.

Stem Cell Transplantation for Frailty

It was reported over 50 years ago that old age is associated with depletion and loss of function of stem cells. Since that time, there has been extensive research confirming the deleterious effects of aging on all types of stem cells, and a growing belief that such age-related changes in stem cells further accelerate tissue and organismal aging. There have also been hundreds of early-phase clinical trials using mesenchymal stem cells (MSCs) for a wide range of disorders including graft-versus-host disease, autoimmune disease, and heart disease where both regenerative and immunomodulatory effects of MSC are harnessed.

The possibility that stem cells might be "vehicles for youthful regeneration of aged tissues" has been well recognized. Mesenchymal stem cells from young mice infused into old mice improved age-related osteoporosis and also increased life span. Transplantation of stem cells from young mice to old mice has also been reported to improve cardiac and reproductive function. There is clearly an opportunity to now undertake clinical trials to explore the therapeutic potential for stem cell transplants for age-related conditions in older humans.

Frailty provides an ideal target for clinical trials of MSC transplantation and aging. Frailty in older humans is associated with reduced circulating MSC, while many of the clinical features of frailty involve mesenchymal tissues, that is, the musculoskeletal system. In clinical practice, the diagnosis is often made based on clinical impression rather than any formal diagnostic process. The definitions of frailty overlap with definitions of aging and sarcopenia. Frailty can be considered to be the end-stage consequence of the biological processes of aging and accumulated chronic disease. Recently two clinical trials were published on the effects of MSC transplantation in frail older humans, and these trials represent potential landmarks in the treatment of frailty. Both studies are early-phase trials of a small number of participants, designed primarily to assess safety, so conclusions about efficacy need to be treated with caution. Even so, the results are striking and, at minimum, pave the way for large randomized Phase III clinical trials.

The first study was a Phase I open-label trial where allogeneic MSC collected from the bone marrow of younger donors aged 20-45 years were used to treat 15 frail patients (average age 78 years) using a single infusion of either 50, 100, or 200 million cells. After 6 months, outcomes that improved included the 6-minute walk and tumor necrosis factor α (TNFα) levels, with variable improvements in forced expiratory volume in 1 second (FEV1), Mini-Mental State Examination (MMSE), and quality of life. No significant adverse effects were recorded, and only one patient developed antibodies that could potentially neutralize the outcomes.

The second study by the same group was a Phase II randomized, double-blinded trial of allogeneic MSC at two doses (100 or 200 million cells) versus placebo. The participants were 30 frail patients with an average age of 76 years. No therapy-related adverse effects were documented at 1 month. Improvements were reported for physical performance, the 6-minute walk test, short physical performance exam, FEV1, and TNFα mostly in the 100 million cell groups. The authors conclude that the treated groups had "remarkable improvements" in outcomes. There are always caveats associated with interpreting efficacy in small numbers of subjects, yet it is remarkable that a single treatment seems to have generated improvement in key features of frailty that are sustained for many months.

Allogeneic Human Mesenchymal Stem Cell Infusions for Aging Frailty

The purpose of this Phase 1 pilot study, AllogeneiC Human Mesenchymal Stem Cell in Patients with Aging FRailTy via IntravenoUS Delivery (CRATUS), was to evaluate the safety and tolerability of allogeneic hMSCs (allo-hMSCs) in patients with aging frailty and to explore domains of treatment efficacy of allo-hMSCs through the reduction of signs and symptoms of aging frailty. The major new findings of CRATUS are that intravenous allo-hMSC infusions are safe and well tolerated in elderly individuals with early signs and symptoms of frailty. Importantly, there were improvements in a constellation of parameters that are important predictors of morbidity and mortality in patients with aging frailty.

With no current standard of care for frailty, allo-hMSCs may hold great promise as a cell therapy agent for patients with this syndrome. The underlying basis for positive effects of allo-MSCs are likely due, at least in part, to anti-inflammatory and proregenerative effects. In this regard, frailty is characterized by systemic inflammation and low "reserve capacity" of organ systems thought due to diminished endogenous stem cell production. Replenishment of the body's stem cell "factory" and/or revitalization of stem cell niches via intravenous infusion of allo-hMSCs may help treat the morbidities associated with aging frailty.

Allogeneic Mesenchymal Stem Cells Ameliorate Aging Frailty: A Phase II Randomized, Double-Blind, Placebo-Controlled Clinical Trial

There are no specific medical or biologic treatments that ameliorate or reverse frailty. Stem cell depletion is a key mechanism postulated to contribute to frailty. In this regard, we recently conducted a phase I open label study of human allogeneic mesenchymal stem cells (allo-hMSCs) intravenously infused for frailty, which showed that the cells could be safely administered, improved measures of functional capacity, and reduced inflammation. Therefore, we conducted the current phase II double-blinded and placebo-controlled study in order to test the hypothesis that exogenous allo-hMSCs could reverse signs and symptoms of frailty in older individuals.

Similar approaches have been shown to exert beneficial effects on the cardiovascular system, with functional improvements on various types of heart disease, endothelial function, and systemic inflammation. Given their pleiotropic mechanisms of action, which include antifibrotic, anti-inflammatory, proangiogenic properties, and their ability to stimulate endogenous progenitor cells, we hypothesize that their use may offer a novel treatment strategy in frail patients.

The findings here replicate in large part the results of the earlier open label study, support the concept that MSCs have bioactivity against aging frailty, and confirm the fact that 100 million cells represents a superior dose level compared to 200 million. The reasons underlying the inverse dose relationship noted here remain incompletely understood. The 100 million dose group produced significant improvements in both physiologic and immunologic markers of frailty, while the high dose group solely demonstrated positive immunomodulatory effects.

Compensation is not a Cure: an Example Involving Blood Pressure

Near the entire corpus of present day medicine for age-related disease, even the comparatively successful treatments, is essentially compensatory in nature. It fails to address in any meaningful way the underlying causes of aging and disease. "Comparatively successful" is presently measured against doing nothing, rather than against the goal of a cure, of controlling the aging process. By that latter standard, there is no such thing as successful medicine for age-related disease. Yet.

The research noted here is one small demonstration of the point that compensatory efforts fail because they do not address the root causes of the problem: the underlying pathology marches on, overwhelms the bounds of possible compensatory efforts, and patients decline and die as a result. Blood pressure rises with age because blood vessels stiffen, because of persistent cross-links in the extracellular matrix, and because of calcification encouraged by the presence of senescent cells, and because of related dysfunctions in the signaling mechanisms that coordinate vascular contractions and reactions to pressure. Current pharmaceuticals that do reliably lower blood pressure do nothing for the roots of the issue.

Hypertension affects about 40% of those aged over 25 and is a major risk factor for heart disease, stroke and kidney failure. An interdisciplinary group of scientists found that conventional medication aimed at reducing high blood pressure restored normal vascular rhythms only in the largest blood vessels but not the smallest ones. "It is clear that current anti-hypertensive treatments, while successfully controlling blood pressure, do not restore microvascular function."

Based on a networks physiology approach, the researchers compared a group aged in their twenties and two older groups aged around 70 - one with no history of hypertension and the other taking medications for high blood pressure. In the older group being treated for high blood pressure the drug treatment restored normal function at the level of arterioles and larger vessels. But when the researchers studied the nonlinear dynamical properties of the smallest blood vessels in the body, they found differences between the two older groups.

"Specifically, current hypertensive treatment did not fully restore the coherence or the strength of coupling between oscillations in the heart rate, respiration, and vascular rhythms (vasomotion). These are thought to be important in the efficient and adaptive behaviour of the cardiovascular system. Indeed, one aspect of ageing is the progressive physiological weakening of these links that keep the cardiovascular system reactive and functional. The results have not only confirmed previous observations of progressive impairment with age of the underlying mechanisms of coordination between cardiac and microvascular activity, but for the first time have revealed that these effects are exacerbated in hypertension. Current antihypertensive treatment is evidently unable to correct this dysfunction."


Outliers Such as Mole Rats Break and Enhance the Models of Aging and Metabolism

Models and trends established across collections of species are used as a tool to try to understand the complex relationship between metabolism and aging, meaning how exactly the natural variations between individuals and species arise from the behavior of cells and interaction with the surrounding environment. This is something of a sideshow to the main business of rejuvenation research, but since the scientific impulse is to map and understand, there is much more of the sideshow taking place than actual efforts to repair the causes of aging. In this slow and expensive business of deciphering the detailed progression of aging, the greatest insight can arise from the outlying examples that do not fit into the models and hypotheses that manage to explain most observations. Some of the various long-lived mole-rat species provide good examples of the type, as illustrated by this open access paper.

Reproduction is an energetically expensive process that supposedly impairs somatic integrity in the long term, because resources are limited and have to be allocated between reproduction and somatic maintenance, as predicted by the life history trade-off model. The consequence of reduced investment in somatic maintenance is a gradual deterioration of function, i.e. senescence. However, this classical trade-off model gets challenged by an increasing number of contradicting studies that show no negative effect of high metabolic rate on lifespan, or even a positive association. Consequently, more research is needed to gather representative data from animals with different life histories, to gain a comprehensive understanding of how life history trade-offs influence lifespan.

Ansell's mole-rats (Fukomys anselli) are subterranean rodents with an extraordinary long lifespan, 22 years being the maximum recorded age thus far. They live in multigenerational families where typically only the founder pair (breeders) reproduces. Most of the offspring (non-breeders) forego reproduction and remain in the natal family. A clear contradiction to the classic trade-off model has been shown in this species: breeding individuals live up to twice as long as their non-breeding counterparts, a feature which is unique amongst mammals. Previous studies showed that daily activity between breeders and non-breeders does not show differences, and social rank does not influence life expectancy. Hence, extrinsic factors like aggression, fighting and higher workload in non-breeders are not likely to influence the lifespan difference. Here, we test the hypothesis that breeders and non-breeders of Ansell's mole-rats differ in their mass specific resting metabolic rate (msRMR), as a possible approach to understand the bimodal aging pattern.

Low msRMR is a common trait in bathyergid rodents interpreted as an adaptation to the subterranean habitat, and our measurements generally confirm previous studies. However, our finding that long-lived breeders of F. anselli have higher metabolic rates compared to shorter-lived non-breeders is novel. This aspect is most interesting since investment in reproduction was long thought to impair somatic maintenance according to the classical trade-off model, but recent findings refer to the trade-off model as being too simplistic. Especially in terms of female reproduction, a meta-analysis from different homeothermic vertebrates has shown that in intraspecific comparisons between breeders and non-breeders, breeders had lower levels of oxidative damage in certain tissues.

This effect could be attributed to upregulation of antioxidant defense mechanisms, such as glutathione or superoxide dismutase activity, which shows a tissue-dependent upregulation in several species during reproduction. This oxidative shielding hypothesis, even if not consistent across different studies, suggests a reproduction-induced protection of mothers and offspring. Ansell's mole-rats are continuously reproducing once they achieve the reproductive status. Oxidative shielding might protect the animals from detrimental pregnancy effects due to a higher energy turnover in female breeders compared to non-breeders. However, the bimodal lifespan in Ansell's mole-rats is not sex-dependent, indicating a general effect in terms of reproductive status, msRMR, and lifespan rather than just a pregnancy effect restricted to females.

Oxidative stress as a main factor contributing to life history trade-offs is getting challenged by increasing contradictory studies. The uncoupling-to-survive hypothesis complements simplistic theories of senescence by explaining apparent exceptions. It suggests that elevated oxygen consumption, a measure for msRMR in the present study, could be also observed due to uncoupling of proton flux in the mitochondria. This process, also referred to as inducible proton-leak, is facilitated by uncoupling proteins and increases RMR. On the other hand, inducible proton-leak is known to reduce ROS production by reducing mitochondrial membrane potentials. Hence the higher msRMR measured in breeders of Ansell's mole-rats could be due to higher rates of mitochondrial uncoupling compared to non-breeders.

Several studies found higher rates of uncoupling in those laboratory mice that lived longer compared to other individuals with shorter lifespans. However, in the case of mole-rats this model should be considered carefully, since in naked mole-rats, surprisingly high levels of oxidative damage to DNA, lipids and proteins were found, which contrasts with the proposed benefit of mitochondrial uncoupling. In general, our finding stresses the complexity of currently discussed aging mechanisms.


The 2017 Winter SENS Rejuvenation Research Fundraiser: Become a SENS Patron, and Your Donations are Matched

This year's SENS Research Foundation winter fundraiser launches today, with a target of $250,000. Donations will support ongoing rejuvenation research programs at the SENS Research Foundation Research Center, as well as in laboratories at Yale, the Buck Institute, the Babraham Institute, and Oxford. The SENS Research Foundation continues to carefully unblock important but neglected fields of research that are relevant to repairing the cell and tissue damage that causes aging - you might take a look at the SENS timeline to see the past and presently ongoing success stories, in which charitable donations were used to move promising research from idea to demonstration to commercial development. A range of important research programs are still in the early stages or the middle of this process, and thus the more that we support these efforts, the faster the progress towards a comprehensive suite of rejuvenation therapies capable of turning back aging and age-related disease.

Following last year's model, Josh Triplett, Christophe and Dominique Cornuejols, and Fight Aging! have put together a $36,000 challenge fund for SENS Patrons. We will match the next year of donations for anyone who becomes a SENS Patron by signing up as a new monthly donor at the SENS Research Foundation between now and December 31st of this year. I invite you all to please put your best foot forward and help out. The SENS Research Foundation is a 501(c)(3) charity, and donations are tax deductible, even in much of Europe, though the details are a little more complex, and vary by country. Tell a friend. Print out and put up one of our posters. Set up a fundraising exercise of your own - there are many ways to help out.

I might be just a touch biased on this topic, but to my eyes supporting this cause is truly effective altruism. Not just because aging is the greatest cause of pain, suffering, and death in the world - by a large margin, and the poor suffer the most, as is always the case - but because the SENS Research Foundation, and the Methuselah Foundation before it, have a proven track record when it comes to turning philanthropic donations for SENS research programs into concrete progress towards human rejuvenation.

Past charitable donors have seen a number of strategic investments in promising but underfunded research turn their donations into active commercial development efforts. For example: work on preventing the consequences of mitochondrial DNA damage, one of the root causes of aging, through allotopic expression of mitochondrial genes was funded with modest support starting back in 2008. That gave rise to Gensight, a company that now puts tens of millions of dollars into developing this technology. SENS programs that mined bacteria for enzymes capable of safely breaking down age-related metabolic waste have resulted in candidates for drug development that are licensed out to the LysoClear program to tackle age-related macular degeneration, and to for efforts to break down some of the harmful compounds that contribute to atherosclerosis. Further, efforts to remove the transthyretin amyloid connected to heart disease, using catalytic antibodies, have moved into a company for commercial development. More is on the way. This year, work on an important component of a universal cancer therapy, achieved through suppression of telomere lengthening, is being spun out, along with promising work on glucosepane cross-link breaking - one of the more important causes of the loss of tissue elasticity that damages skin and, more importantly, blood vessels.

The SENS Research Foundation has also funded research in cellular senescence in aging, and SENS advocates has persistently and actively fought for more funding for this line of development for fifteen years. This helped to bring to an end the long period during which the research community rejected this very important field of research. As senolytic therapies to clear senescent cells have finally blossomed into a suddenly popular area of development, the SENS Research Foundation helped to seed fund the startup Oisin Biotechnologies, working on a gene therapy approach to selectively destroy senescent cells and cancerous cells with minimal side-effects. That company is presently raising a new round of funding to take their work to the clinic.

As a final item to consider, remember that all of this exciting progress towards the end goal of effective human rejuvenation was built atop a modest starting point, that being the small, simple decisions of a few thousand people just like you and I: people who gave a small amount of money every month, such as the members of the Methuselah 300. It is because of these people, their conversations, and their dedication and vision, that the first SENS rejuvenation research programs took place at all. It is because of these people that high net worth individuals such as Peter Thiel, Michael Greve, and Jim Mellon have been drawn to the field to provide significant material support. We make a difference. We are the leaders, we are the people carrying the lantern to light the way. Because of our efforts, the world will be a better place tomorrow, one in which being old doesn't have to mean being sick, frail, and faltering.

Considering Common Mechanisms in Alzheimer's Disease and Osteoporosis

It has been observed that Alzheimer's disease and osteoporosis appear to be correlated to a larger degree than one would expect simply because both emerge, after a long chain of cause and effect, from the root causes of aging. That they are correlated in this way suggests that they share in common some parts of the middle of that long chain. Given that osteoporosis is a condition of the bones, a disruption of the balance between cells that create bone and cells that destroy bone, and Alzheimer's is a condition of the brain, in which aggregated proteins overwhelm cells, what could these two very different outcomes of aging have in common? This open access paper looks at some of the current evidence and hypotheses.

Accumulation of abnormally folded amyloid beta peptide (Aβ) in cerebral amyloid plaques is the pathologic hallmark of Alzheimer's disease (AD). Aβ originates from the amyloid precursor protein (APP), a membrane protein expressed in many tissues and synapses of neurons with unknown function. A group of specific enzymes named secretases cleave APP into distinct fragments. APP cleavage by β-secretase and then γ-secretase leads to pathological Aβ oligomers. Oligomers are the units which form protofibrils and later fibrils and plaques. Genetic models of AD are typically established by excessively expressing Aβ protein and the current hypothesis of AD etiology centers around amyloid plaques.

Unlike the complexity and controversy in AD, the pathogenesis of osteoporosis is known as an imbalance between bone formation and mineralization. Hyperparathyroidism, Vitamin D deficiency, and steroid use are common causes of osteoporosis. Osteoporosis is mostly asymptomatic until minor trauma or falls lead to fractures. Bone formation involves bone matrix production and mineralization, whereas bone resorption is a biological erosive process mediated by osteoclasts. When the balance leans toward bone resorption, bone mineral density (BMD) decreases and osteoporosis develops.

Bone resorption is driven by the receptor activator nuclear factor-kappa B ligand (RANKL) / receptor activator nuclear factor-kappa B (RANK) signaling network, a signaling complex with multiple downstream pathways. The binding of RANKL to RANK triggers the cascade. Amyloid deposition in the brain and RANKL signaling are two seemingly independent pathways leading to AD and osteoporosis. The possible linkage between these two pathways has been investigated by measuring osteoclast activities in a transgenic mice model of AD. Both in vitro and in vivo examinations showed enhanced Aβ expression in bone, together with increased adipose tissue formation in the marrow space, analogous to osteoporotic bones. The abnormally expressed amyloid deposition appears to interfere with the RANKL signaling cascade and in turn the balance between bone formation and bone resorption. Similar findings extend to human studies.

Previous observational studies have reported the increased frequency of comorbid osteoporosis in AD. The relationship between these two diseases is more likely one of shared etiology than one condition causing the other. The overexpression of Aβ may take place in both brain and bone, interfering with the RANKL signaling cascade, enhancing osteoclast activities, and leading to osteoporosis. There is a growing body of evidence from in vitro and in vivo studies that the AD pathology in the brain can be reflected by examining the bone. Future investigation will focus on assessing biomarkers of cognitive aging in patients with osteoporosis and looking into the bone microstructure of patients with AD.


Short-Term Calorie Restriction Boosts Innate Immunity in Flies

Calorie restriction slows aging, with the current consensus being that this is largely mediated through increased autophagy, the housekeeping processes that clear out and recycle broken components within the cell. Calorie restriction does, however, change more or less everything there is to be measured in cellular metabolism, so it is certainly possible that other mechanisms are relevant. In this context, researchers here present evidence to show that, at least in flies, the defense against infection mounted by the innate immune system is enhanced by short term calorie restriction. It is also worth considering that this sort of effect may explain some of the degree to which calorie restriction reduces the burden of cellular senescence and cancer risk over the long term, by incrementally improving the ability of the immune system to remove harmful and potentially harmful cells.

Studies of dietary restriction, a reduction in nutrient intake without malnutrition, in a diverse array of organisms have revealed it to be an effective way to extend lifespan and promote broad-spectrum improvement in health during aging. Early work focused on total caloric intake as the driving force behind these beneficial effects, but studies that have comprehensively examined the effects of individual macronutrients on lifespan underscore the importance of protein-to-carbohydrate ratio. In the fruit fly, Drosophila melanogaster, yeast restriction has been used as an alternative to wholesale dilution of the diet to effectively extend female fly lifespan. These effects have also been observed in mammals, where protein restriction increased rodent lifespan. Together, these studies establish that the life-extending benefits associated with dietary restriction can be achieved without reducing total caloric intake when the relative consumption of protein to carbohydrates is low.

A striking feature of the effects of dietary restriction is its acute nature, yielding beneficial outcomes with short-term application. In Drosophila, a switch to a restricted diet reduced short-term mortality risk within 48 hr, and in mice, 1 week of protein starvation decreased tissue damage caused by temporary blockage of blood flow during surgical operation, greatly improving survival following renal ischemic injury. Even ad libitum feeding of low-protein, high-carbohydrate diets for 8 weeks resulted in metabolic improvement in mice compared to those fed high-protein, low-carbohydrate diets.

A significant threat to global health is infectious diseases. Acute preventative strategies that strengthen immunity prior to such procedures are therefore of strong interest. To answer the questions of whether, similar to general health and aging, innate immune function is acutely modulated by individual nutrients, we executed a comprehensive analysis of the effects of dietary composition on survival following pathogenic infection in Drosophila. Although lacking adaptive immunity, insects are equipped with innate immunity, which is an ancient first-line defense mechanism that recognizes the pattern of invading microorganisms as well as their virulence factors. Drosophila innate immunity has humoral and cellular components, and this innate immune response is highly conserved between Drosophila and mammals.

Here, we present evidence that yeast restriction, but not carbohydrate restriction, substantially improves fly survival following bacterial infection through several components of innate immunity. We find that yeast-restriction-mediated enhancement of innate immunity is orchestrated by components of the target of rapamycin (TOR) signaling network, in which reduced TOR signaling results in a stabilization of the transcription factor Myc through its suppressor protein phosphatase 2A. Myc in turn mediates a sustained induction of genes that encode antimicrobial peptides, which are effective bacterial killers. These results implicate a function for protein phosphatase 2A (PP2A) and Myc as signaling molecules that serve to potentiate the immune response in yeast-restricted animals following pathogenic infection.


Researchers Generate Decellularized Livers, Ready for New Cells and Transplantation

Decellularization is the most promising near term approach to generating patient-matched organs for transplantation. It is a fairly simple concept at root: researchers remove all of the cells from an organ, leaving the scaffold of the extracellular matrix with all of its intricate details and chemical cues. The challenge lies in building a reliable methodology that can be scaled up for widespread use. Much of the work on decellularization to date has focused on hearts and lungs, but in the paper noted here, researchers outline a method for reliably decellularizing whole livers.

Decellularization does of course require a donor organ as a starting point, unfortunately, but that can include a significant fraction of the potential donor organs that would normally be rejected by the medical community for one reason or another, as well as organs from other species, such as pigs. Given suitably genetically engineered pigs, a decellularized pig organ repopulated with human cells should contain no proteins that will provoke significantly harmful responses following transplantation. This and other options should roll out into availability in the years ahead, ahead of the range of more ambitious tissue engineering projects that aim to grow entire organs from a patient cell sample.

Decellularization is ahead of other methodologies for the creation for patient-matched organs because the research community has yet to produce a good method of generating the intricate networks of tiny blood vessels that are needed to support tissue much larger than a millimeter or two in depth - the distance that nutrients can perfuse in the absence of capillaries. Yet over the past few years many research groups have demonstrated the production of organoids, tiny sections of complex, functional organ tissue, for a variety of organs. Thus the actual production of organs from patient cells will be a going concern just as soon as the blood vessel question is figured out. Unfortunately, this has been the state of the field for years now, with many promising leads but no definitive end in sight. Meaningful progress in bringing decellularization to the medical community is to be welcomed in the meanwhile.

Decellularization of Whole Human Liver Grafts Using Controlled Perfusion for Transplantable Organ Bioscaffolds

The only therapy for liver cirrhosis is liver transplantation, but the shortage of organ donors imposes a severe limit to the number of patients who benefit from this therapy. With increasing shortage of donor organs and decrease of their quality, the development of novel procedures and alternatives for organ transplantation becomes essential. Thus, organ engineering, which involves the repopulation of acellular matrices, was explored with the use of polymeric scaffolds or three-dimensional (3D) printing of liver tissue to make scaffolds that can be seeded with hepatocytes or other cell types.

Although these are powerful tools worth exploring, it remains difficult to design and create artificial, yet functional liver tissue with functional vascular and biliary trees for clinical use. Alternatively, removal of cells from an existing organ, leaving a complex mixture of structural and functional proteins that constitute the extracellular matrix (ECM), may provide a natural habitat for reseeding with an appropriate population of cells, and connected to the blood stream and biliary system.

Ideally, ECM is cell free, but remains the interlocking mesh of fibrous proteins (collagen, elastin, fibronectin, and laminin) and glycosaminoglycans (GAGs). Evidence from rodent models shows the feasibility of decellularization of whole liver organs that provides an excellent scaffold for reseeding liver (stem) cells for graft engineering. Also, porcine and sheep liver have been successfully decellularized to obtain ECM for transplantation. However, so far, there is very limited experience with decellularization of whole livers from humans.

Recently, researchers demonstrated efficient decellularization of a whole liver and partial livers to generate small cubes of human liver scaffold. Different decellularization methods have been described among which are physical force (freeze/thaw, sonication, and mechanical agitation), enzymatic agents (trypsin, endonucleases, and exonucleases), and/or chemical agents (ionic, nonionic, and zwitterionic detergents). Usually, combinations of these methods are used. In larger organs, such as human or porcine liver, perfusion through the intrinsic vascular beds is the favorable route to be able to reach all cells. So far, most experimental decellularization protocols include the use of sodium dodecyl sulfate (SDS) to generate full freedom of cells and translucency, but this also progressively destroys the ECM and hampers clinical translation.

In this study, we report successful decellularization of human livers to obtain transplantable whole organ scaffolds. We show proof of concept that these scaffolds can serve as feasible resources for future tissue-engineering purposes. Using a controlled perfusion system, a complete 3D acellular human liver scaffold was generated on a clinically relevant scale and free of allo-antigens. We present the feasibility of systematically upscaling the decellularization process to discarded human livers. Eleven human livers were efficiently decellularized by nonionic detergents by machine perfusion. A careful choice of the decellularization methodology is of great importance as methods described for decellularization may be well suitable for other organs than the liver, but may damage the composition of the matrix proteins.

Repopulation of a complex organ such as the liver poses numerous challenges. Using the extracellular matrix of the native liver obviously helps to create the most optimal niche for cells to repopulate, but the types of cells to be infused to create fully functional liver tissue remains to be elucidated. In addition to the liver-specific matrix proteins, the still present vascular and biliary system may also provide entry routes for the different cell types needed. Obviously, efficient recellularization is a complex process in which hepatocytes or other parenchymal cells need to pass the remnant basement membrane of the decellularized blood vessels or bile ducts to enter the parenchyma after vascular or biliary administration, respectively. In addition, cell numbers that are required for efficient recellularization are highly dependent on cell type and volume of the scaffold.

Reendothelialization is a pivotal step to prevent thrombosis as a result of the massive collagen contact surface that blood will encounter upon reperfusion, and which cannot be prevented by coating with heparin. We demonstrated, like others did in animal models, that matrix sections can be reseeded with endothelial cells and these cells end up at the location of the decellularized blood vessels and pave the basal membrane. In our studies, HUVEC were used as a source of endothelial cells, as in most studies in rodents and pigs, but other sources such as endothelial progenitor cells are also used and show similar results. The next hurdle to be taken toward clinical application is to choose a cell source for liver parenchyma repopulation. An adult liver contains ∼150-350 billion cells of which the largest part (70%-85%) is made up by hepatocytes. However, adult primary hepatocytes of high quality are scarce and therefore limit tissue-engineering applications. Ideally, autologous cells, isolated from the patients themselves, are used as these cells will have a low risk to trigger an immune response. Alternatively, (autologous) pluripotent stem cells that self-renew and are able to differentiate into all cell types needed could be seeded.

In summary, human cadaveric livers can be successfully decellularized using machine perfusion and nonionic detergents, and can be repopulated with endothelial cells. The next steps toward clinical application involve finding a cell source or combinations of cell types to reseed the matrix, including the vascular and biliary system, to gain functional liver tissue.

The Roles of mTOR in Aging

Next to insulin signaling, the biochemistry surrounding mechanistic target of rapamycin (mTOR) is probably the greatest point of study for that part of the mainstream research community interested in modestly slowing aging through pharmaceuticals, researchers who generally show little interest in the alternative approach of repairing the causes of aging to produce rejuvenation. Drugs and drug candidates to slow aging are largely intended to adjust the operation of cellular metabolism involved in nutrient sensing to mimic some of the beneficial response to calorie restriction, such as increased autophagy. mTOR is, as one might imagine, the primary target for the action of rapamycin, and similar pharmaceuticals known as rapalogs, that inhibit mTOR and have been shown to slow aging in mice. The paper here is a good summary of present knowledge on the subject.

The most studied and best understood longevity pathways govern metabolism according to available nutrient levels. The fundamental mechanisms from signaling cascades to protein complexes are conserved across phyla. A controlling hub at the center of nutrient sensing and signaling is the mechanistic target of rapamycin (mTOR) that governs cellular growth, protein synthesis, and degradation. mTOR acts upstream of several transcription factors, such as TFEB, FOXO, FOXA, and Nrf, that are essential for lifespan-extending strategies such as dietary restriction. These transcription factors also control autophagy, a cellular process that clears proteins and dysfunctional organelles, and reduces proteotoxic and oxidative stress while maintaining a pool of amino acids for protein synthesis. mTOR responds to amino acids, a pathway modulated by proteins such as sestrins.

Here we will review the current knowledge on the best-known longevity pathways across animal models, namely insulin/insulin-like signaling and its downstream transcription factor FOXO, and transcription factor FOXA-dependent signaling. We consider how FOXO and FOXA are regulated by mTOR, and what role autophagy plays in the lifespan extension they confer. We also consider additional longevity mechanisms that rely on lipid signaling and the proteasome. We conclude with a discussion of how advancements in technologies such as induced pluripotent stem cells can enable the study of longevity-regulating mechanisms in human systems, and how emerging ideas on nuclear-cytoplasmic compartmentalization and its loss could contribute to our understanding of transcriptional dysregulation of nutrient-sensing pathways in aging.

The mechanism through which mTOR accelerates cellular and organismal aging is still unclear, but causative elements discussed include increased oxidative and proteotoxic stress associated with mTOR-mediated mRNA translation and inhibition of autophagy resulting in the accumulation of defective organelles, including mitochondria. It is important to emphasize the complexity of the pathway: mTOR regulates metabolic transcription factors and can be regulated by the same transcription factors, such as TFEB and FOXO, and mTOR is able to regulate nuclear morphology and induce epigenetic changes by which it is affected.

Several components of the mTOR pathway have still not been investigated in the context of aging and longevity. It is possible that differential expression or activity of TOR-regulating proteins can be part of the age-associated changes in the base level of mTOR signaling, associated also with a decline in protein turnover and autophagy, and increase in protein aggregation. Another possible way the regulation of these longevity-driving processes could deteriorate over time is the loss of nucleocytoplasmic compartmentalization, as seen in progeria, and also in healthy aged individuals, whose cells show evidence of increased nuclear membrane blebbing and progerin buildup. In addition to the recorded effects of this loss on DNA damage and promotion of cellular senescence, further aggravated with simultaneously increased mTOR signaling, this could possibly disable the highly controlled localization of transcription factors, including those regulating processes related to aging, feeding into a vicious cycle of perturbed metabolism and homeostasis.

Rapamycin has recently been shown to alleviate some aging phenotypes while exacerbating others. These results could be due at least in part to attenuated mTORC2 activity, the loss of which has been shown to reduce longevity in Caenorhabditis elegans and in liver-specific mTORC2 knockout mice, while inhibition of mTORC1 is largely viewed as advantageous. Development of new drugs targeting the amino acid sensing pathway may increase selectivity to mTORC1 and enable assessments of longevity changes upon pharmacological complex-specific mTOR inhibition.


No Great Surprises in a Recent Study of the Causes of Variation in Human Lifespan

A recent study of human life expectancy uses a novel approach but the results offer no real surprises, confirming most of the current consensus associations. As a tour of the high level points, it is worth skimming. There are few genetic relationships that are large enough to be seen, and those that are visible are small in comparison to the impact of lifestyle choices. Excess fat tissue is just about as harmful as smoking for the obese: two months of life expectancy lost for every kilogram of excess weight. This all confirms the long-standing common wisdom when it comes to maintaining health for the long term - but also shows that the scope of the possible in the absence of rejuvenation therapies is very limited. You can move your life expectancy a few years up or a good many years down given the tools and techniques of yesterday. For more than that, we must look to the SENS research programs and similar efforts to repair the cell and tissue damage that causes aging.

Longevity is of interest to us all, and philosophers have long speculated on the extent to which it is pre-determined by fate. Here we focus on a narrower question - the extent and nature of its genetic basis and how this inter-relates with that of health and disease traits. In what follows, we shall use longevity as an umbrella term. We shall also more specifically refer to lifespan (the duration of life) and long-livedness (living to extreme old age, usually defined by a threshold, such as 90 years). Up to 25% of the variability in human lifespan has been estimated to be genetic, but genetic variation at only three loci (near APOE, FOXO3A and CHRNA3/5) have so far been demonstrated to be robustly associated with lifespan.

Prospective genomic studies of lifespan have been hampered by the fact that subject participation is often only recent, allowing insufficient follow-up time for a well-powered analysis of participant survival. On the other hand, case-control studies of long-livedness have had success and some technical appeal (focusing on the truly remarkable), but such studies can be limited and costly in their recruitment. We recently showed that the extension of the kin-cohort method to parental lifespans, beyond age 40, of genotyped subjects could be used to detect genetic associations with lifespan with some power in genomically British participants in UK Biobank (UKB).

Here we extend that approach in a genome-wide association meta-analysis (GWAMA) to discovery across UKB European- and African-ancestry populations and 24 further population studies (LifeGen), mainly from Europe, Australia and North America, to search for further genetic variants influencing longevity. We then use those GWAMA results to measure genetic correlations and carry out Mendelian randomisation (MR) between other traits and lifespan seeking to elucidate the underlying effects of disease and socio-economic traits on longevity, in a framework less hampered by confounding and reverse causality than observational epidemiology.

We replicated previous findings of genome-wide significant associations between longevity and variants at CHRNA3/5 and APOE and discovered two further associations, at LPA and HLA-DQA1/DRB1, with replication of the further associations in a long-livedness study. We found no evidence of association between lifespan and the other 10 loci previously found to suggestively associate with lifespan, despite apparent power to do so. We showed strong negative genetic correlation between coronary artery disease (CAD), smoking, and type 2 diabetes and lifespan, while education and openness to experience were positively genetically correlated. Using MR, we found that moving from the 25th to 75th percentile of cigarettes per day, systolic blood pressure, fasting insulin and body mass index (BMI) causally reduced lifespan by 5.3, 5.2, 4.1 and 3.8 years, respectively, and similarly moving from the 25th to 75th percentile of educational attainment causally extended lifespan by 4.7 years.

Our finding that a reduction in one BMI unit leads to a 7-month extension of life expectancy, appears broadly consistent with those recently published by the Global BMI Mortality Collaboration, where great effort was made to exclude confounding and reverse causalit7. We also found each year longer spent in education translates into approximately a year longer lifespan. When compared using the interquartile distance, risk factors generally exhibited stronger effects on mortality than disease susceptibility. Although both CAD and cigarette smoking show a very similar genetic correlation with lifespan, the measured effect of smoking is twice as large as that of CAD, perhaps because smoking influences mortality through multiple pathways.

Our results show that longevity is partly determined by the predisposition to common diseases and, to an even greater extent, by modifiable risk factors. The genetic architecture of lifespan appears complex and diverse and there appears to be no single genetic elixir of long life.


Immune Cell Telomeres and Senescence in the Context of Viral Infection and Aging

It is considered that a sizable component of the disarray of the aged immune system is caused by cytomegalovirus infection, and here I thought I'd note a couple of recent papers that touch on the intersection between this topic and the measurement of telomere length. The herpesvirus cytomegalovirus cannot be cleared from the body by the immune system; it lurks and reappears again and again, but causes few or no obvious issues in the vast majority of individuals beyond this one long-term problem. It is pervasive, and more than 90% of the population is infected by the time they reach old age. Ever more immune cells become specialized to attack cytomegalovirus, that number expanding rapidly in later life. The immune system operates with only a low rate of replacement cells, which makes it act very much like a space-limited system, with a ceiling on the number of cells it can support at once. Too much of its limited count of cells becomes taken up by cytomegalovirus-specific cells that are incapable of performing all the other necessary tasks, such as destroying cancerous cells, or attacking novel, unrecognized pathogens.

At present telomere length is usually measured in immune cells taken from a blood sample. Considered over a population, average telomere length via this measure tends to trend down over the course of a lifetime. Individuals can vary considerably, however, and average length bounces up and down quite dynamically with health changes and other short-term environmental factors. It isn't much use as a metric for any sort of individual assessment. What does telomere length even signify? Well, every time a cell divides, telomeres shorten a little. When they get too short, the cell self-destructs or becomes senescent, ceases to divide, and is then usually destroyed by the immune system. Stem cells, however, maintain long telomeres via use of telomerase, and carry out their task of tissue maintenance by delivering a supply of new daughter cells with long telomeres. So average telomere length in any cell population is a smeared-out metric that reflects something of cell division rates and something of stem cell activity rates. We know that stem cell activity declines with age, and this would be enough for us to expect some sort of fall in average telomere length.

Immune cells division rates are greatly influenced by many factors that are not relevant in other cell types: the presence of pathogens; the degree to which tissues are generating inflammatory signals; and so forth. In particular, we would expect persistent pathogens such as herpesviruses and HIV to push the immune system into greater replication, shorter telomeres, high rates of senescence, and general exhaustion as a result - which appears to be the case. What can be done about the issue, however? The most promising line of attack for cytomegalovirus, a mostly harmless pathogen aside from its decades-long grinding down of the immune system, appears not to be to tackle the virus itself, but to periodically destroy and replace all of the problem immune cells. Getting rid of cytomegalovirus would be a nice bonus on top of that, but not of any great use in and of itself for old people. The damage has already been done. Immune destruction and recreation isn't pie in the sky: it is already being accomplished in the context of curing serious autoimmune conditions. However, the therapeutic approaches used are presently fairly damaging, akin to chemotherapy in impact on the patient. Given better and more gentle methodologies of selective cell destruction - such as those under development at Oisin Biotechnologies, among others - then this will become a very plausible prospect.

Telomere Dynamics in Immune Senescence and Exhaustion Triggered by Chronic Viral Infection

The progressive loss of immunological memory during aging correlates with a reduced proliferative capacity and shortened telomeres of T cells. Growing evidence suggests that this phenotype is recapitulated during chronic viral infection. The antigenic volume imposed by persistent and latent viruses exposes the immune system to unique challenges that lead to host T-cell exhaustion, characterized by impaired T-cell functions. These dysfunctional memory T cells lack telomerase, the protein capable of extending and stabilizing chromosome ends, imposing constraints on telomere dynamics.

Unlike normal memory T cells, which persist due to the levels of interleukin-7 (IL-7) and IL-15, exhausted T cells only require the presence of viral antigen to continue proliferating. This is partly due to losses in interleukin-2 receptor-β (CD122) and interleukin-7 receptor (CD127) that limit generation of virus specific T cells. Because viral antigen is intermittently or constantly supplied to these cells, viral specific T cells never cease proliferating. Depending on the length of infection, this could result in progressively shorter telomeres and an age-related decline in T-cell responses.

A deleterious consequence of excessive telomere shortening is the premature induction of replicative senescence of CD8+ T cells. While senescent cells are unable to expand, they can survive for extended periods of time, occupying immunological space where functional immune cells could exist. The accumulation of senescent CD8+ T cells has been proposed to play a role in failed immune surveillance and in facilitating the development of metastasis of certain cancer types. Interestingly, some studies proposed that it may be possible to reverse this phenotype by reactivating telomerase expression.

Evidence is mounting that high levels of antigen stimulation result in excessive proliferation, driving cells into a state of replicative senescence due to telomere attrition. The benefits for addressing viral T-cell exhaustion and immune senescence in patients with chronic viral infections and chronic inflammatory or auto-immune diseases are great so as to finally eradicate the chronic virus. Therefore, it is relevant to the ongoing efforts to develop therapeutic vaccines aimed at stimulating CD8+ T-cell responses and current immunotherapy based on adoptive transfer of expanded virus-specific CD8+ T cells.

There are still many questions when it comes to the therapeutic potential of blocking T-cell exhaustion. One concern is whether fully exhausted T cells can be reactivated. If exhausted T cells have reached a state of terminal differentiation, they may have undergone permanent cell cycle arrest and irreversible cellular senescence. In this case, it is important that anti-exhaustion therapy (such as drugs to block immune inhibitory markers) be given at the proper time, before the cells become permanently differentiated. In the latter case, it would then be imperative to target these cells for removal through enhanced cell death, since reactivation is not possible.

Telomere Shortening, Inflammatory Cytokines, and Anti-Cytomegalovirus Antibody Follow Distinct Age-Associated Trajectories in Humans

Chronic infection with cytomegalovirus (CMV) has a profound impact on the immune system and is considered one of the causes of immunosenescence in the elderly. The serum titer of CMV-specific IgG has been widely used as an indicator of CMV infection status, but its significance in immunosenescence is less well defined. Age-associated increase in anti-CMV IgG has been reported from cross-sectional studies, but its trajectory has not been analyzed in longitudinal studies. Although a recent study found no difference of telomere length in subjects between CMV seropositive and negative from a cross-sectional analysis, it is unknown whether the rates of changes of these age-associated biomarkers in vivo are correlated or independent.

In this study, we sought to measure the in vivo changes of telomere length, inflammation-related cytokine and anti-CMV antibody titer with age and to determine the trajectory of these age-associated immune changes and their inter-relationship using longitudinal analysis over an average of 13 years. Specifically, we assessed the individual longitudinal trajectories of peripheral blood mononuclear cell (PBMC) telomere length, eight pro-inflammatory cytokines, and anti-CMV IgG titer in 456 subjects. Strikingly, aging-associated changes in these variables occur with a distinct trajectory in each individual. Thus, immune aging is a heterogeneous process across individuals, and an assessment of immunosenescence requires a combinatorial evaluation of multiple age-associated biomarkers.

Although aging affects multiple organs and tissues, the rates of age-related changes display a remarkable degree of variation within the human population. Our previous longitudinal studies of aging of the immune system assessed immune cell composition and telomere length, and demonstrated highly individualized changes. Overall, the results of our longitudinal studies suggest that the manifestations of aging-associated changes in the immune system are multifaceted and exhibit independent trajectories. These findings suggest that there is no dominant integrator among the three classes of age-related change studied here: telomere attrition in PBMCs, increased circulating IFN-γ and IL-6, and increased titers of anti-CMV IgG.

In contrast to the disassociation among age-related changes in telomere length of PBMCs, circulating inflammatory cytokines, and titer of anti-CMV IgG, the changes of various inflammatory cytokines with age show a number of positive correlations. The rate of increase in IL-6 is positively correlated with the rate of change in IL-4, and the rate of IL-1β is positively correlated with the rates of IL-13, IL-12p70, and IL-2. Although not all these cytokines displayed statistically significant age-associated changes, this suggests that the expression of these multiple pro-inflammatory cytokines may be regulated by common stimulators and/or that these cytokines may regulate one another in an autocrine and paracrine fashion. This mutual enhancement of inflammatory cytokine expression may explain why the increase in pro-inflammatory cytokines with age is rarely limited to a single cytokine.

Bubr1 and Brain Aging

In mice, loss of Bubr1 produces high levels of DNA damage, cancer, and the appearance of accelerated aging. The proteins produced by this gene are an important part of the mechanisms controlling cell division, and their absence results in all sorts of harm to chromosomal structures. As is true of many such progeroid mechanisms related to DNA damage, it remains an open question as to whether Bubr1 is also relevant in normal aging. Interestingly, the production of artificially increased levels of Bubr1 in mice does modestly slow some measures of aging - but the effects on life span may be due to a reduction in cancer incidence rather than any other effect on the processes of aging. It is much harder than you might think to peel apart the various influences and causes in studies of this nature. One of the areas of focus in the study of Bubr1 and aging is the brain and its loss of function, particularly the declining rate at which new neurons are created; here is a short overview of recent research on this topic.

The hippocampus is one neurogenic region in the adult mammalian brain that continues to produce neurons well into adulthood. This process of neurogenesis occurs in the subgranular zone (SGZ) of the hippocampal dentate gyrus that harbors neural stem cells (NSCs). These actively participate in a sequential process where they proliferate, migrate and mature into neurons that are functionally integrated into the hippocampal circuitry. This is a highly plastic process that affords the hippocampus roles in memory formation, learning, and mood regulation. However, it is also an age-dependent one where the number of NSCs decline with age. Age-related cognitive disability is one example of the functional implications of deficits in this process. A molecular understanding of this course has so far eluded the field. Recent evidence has demonstrated that BubR1, a mitotic checkpoint kinase, decreases with natural aging and induces progeroid features and aging-related central nervous system (CNS) abnormalities. In our recent study we sought to address if BubR1 played a role in age-related hippocampal changes.

In this study, we show BubR1 is expressed in the radial-glia like NSCs (RGC), and its expression is reduced in an age-dependent manner. We used progeroid BubR1H/H mice with reduced hippocampal BubR1 levels to show significantly reduced proliferation. Progenitor cell types vulnerable to BubR1 insufficiency included significant reductions in activated RGCs, intermediate progenitor cells, and neuroblasts. Such changes in cellular proliferation were exacerbated in BubR1 H/H mice in an age-dependent manner. Next, we sought to address if BubR1 played a role in maturation of the surviving neurons. An in vitro analysis using post-mitotic neurons derived from adult NSCs showed BubR1 localization in the dendrites and the cytoplasm. BubR1H/H mice showed a significant increase in the portion of immature neurons with a concurrent decrease in mature neurons, indicating delayed neuronal maturation in BubR1H/H mice. Importantly, these morphological alterations were significantly rescued in BubR1-overexpression mice, suggesting a critical post-mitotic role of BubR1 in newborn neurons.

This study expands on the varied and emerging functions of BubR1 and implicates it as a key regulator in the age-dependent changes in adult hippocampal neurogenesis. In addition, while BubR1 is primarily known as a key component for mitosis, our study is the first to delineate the critical post-mitotic role for BubR1 in neuronal maturation. However, this study does not yet provide the mechanistic link or elucidation of the molecular machinery that occurs between BubR1 decrease and significant reductions in proliferation and maturation of newborn hippocampal neurons. Recent studies from our lab have identified involvement of Wnt signaling as a novel molecular regulator to this process. Furthermore, it remains to be understood if sustained BubR1 levels during aging process may have a protective role in the aged brain, and thus represent a novel therapeutic target for age-related cognitive declines. This is a future direction that can shed further light on BubR1 and aging.


Healthier Older People have a Gut Microbiome More Like that of Younger People

The research community has amassed a fair amount of evidence to show that the composition of the gut microbiome changes with aging and has some influence over the pace of aging. Consider interactions between gut bacteria and the immune system, and the degree to which it promotes chronic inflammation, for example. Other mechanisms by which our gut microbes influence systems and organs are also being uncovered of late. Just how much the gut microbiome contributes to natural variations in human life span remains an open question: is it on a par with exercise and calorie intake, or a lesser influence? Further, are changes in the gut microbiome a consequence of lifestyle choices or are they a more independent factor? Research such as the program noted here attempts to put some bounds to the possible range of answers.

In one of the largest microbiota studies conducted in humans, researchers have shown a potential link between healthy aging and a healthy gut. The researchers studied the gut bacteria in a cohort of more than 1,000 Chinese individuals in a variety of age-ranges from 3 to over 100 years-old who were self-selected to be extremely healthy with no known health issues and no family history of disease. The results showed a direct correlation between health and the microbes in the intestine. "It begs the question - if you can stay active and eat well, will you age better, or is healthy aging predicated by the bacteria in your gut?"

The study showed that the overall microbiota composition of the healthy elderly group was similar to that of people decades younger, and that the gut microbiota differed little between individuals from the ages of 30 to over 100. "The main conclusion is that if you are ridiculously healthy and 90 years old, your gut microbiota is not that different from a healthy 30 year old in the same population." Whether this is cause or effect is unknown, but the study authors point out that it is the diversity of the gut microbiota that remained the same through their study group. "This demonstrates that maintaining diversity of your gut as you age is a low-cholesterol is a biomarker of a healthy circulatory system." The researchers suggest that resetting an elderly microbiota to that of a 30-year-old might help promote health.


POT1 is a Second Shelterin Component that Influences Aspects of Aging

You might recall that researchers recently demonstrated that increased levels of TRF1, a component of the shelterin protein complex, could modestly extend healthy (but not overall) life span in mice. The effect is likely mediated through raised levels of stem cell activity in older individuals, somewhat turning back the usual trend towards declining tissue maintenance. The paper I'll point out today makes an good companion piece, in that it examines the shelterin component POT1, finding that increased levels of this protein also help to maintain stem cell activity. Both POT1 and TRF1 decline with advancing age, and the argument made by some researchers is that shelterin activity is one of the more relevant mechanisms in stem cell aging. That, of course, says comparatively little about where this fits in the chain of cause and effect. If there is less POT1 and TRF1, what caused that? I'm inclined to think that changes in protein expression, and the epigenetic alterations needed to increase or decrease production of proteins from their genetic blueprints, are reactions to more fundamental cell and tissue damage.

What is shelterin and what does it do? This complex is involved in defending telomeres, the repeated DNA sequences found at the end of chromosomes, from various DNA repair and other processes that would cheerfully and destructively cut them short at any moment. Telomere length is an important part of the mechanisms that permit or restrict cell replication: a little of their length is lost with each cell division, and when too short a cell either becomes senescent or self-destructs. The vast majority of cells in the body are restricted in the number of divisions they can carry out, on a countdown to destruction, and this is the foundation of all of the methods used by complex organisms such as mammals to suppress cancer to a sufficient degree to get by. Only a small number of cells, the germline and the stem cells responsible for tissue maintenance, use telomerase to lengthen their telomeres and thus replicate indefinitely. Keeping only a small number of cells privileged in this way greatly reduces the risk of one of them becoming damaged in a way that causes it to run rampant, the seed for a cancer. Too little shelterin and stem cells start to fail in their self-renewal, becoming inactive, senescent, or destroying themselves, because they progressively fail to maintain their long telomeres. More shelterin produces the opposite effect, making stem cell populations better maintained and more active in older individuals.

Stem cells have evolved to decline with age. The current consensus is that this, like a very large number of line items in cellular biochemistry, involves resistance to cancer. Evolutionary pressures lead to a species that attains a certain life span, but how exactly that life span is achieved by cell biochemistry may vary. Our species, long-lived in comparison to our nearest primate cousins, appears to have achieved a large enough resistance to cancer to obtain those additional years at the cost of a slow decline into frailty and organ failure. It doesn't have to be that way - one can look at elephants, for example, who achieved sufficient resistance to cancer to live as long as they do via much more efficient cancer suppression mechanisms. In this context, each species' biochemistry ends up where it does through the forces of natural selection favoring a certain life span, interacting with the happenstance of moving from point A to point B in the biochemistry of cells through evolutionary time. Changes in the availability of shelterin over a lifetime are just one small part of this picture.

The telomere binding protein Pot1 maintains haematopoietic stem cell activity with age

Appropriate regulation of haematopoietic stem cell (HSC) self-renewal is critical for the maintenance of life long hematopoiesis. However, long-term repeated cell divisions induce the accumulation of DNA damage, which, along with replication stress, significantly compromises HSC function. This sensitivity to stress-induced DNA-damage is a primary obstacle to establishing robust protocols for the ex vivo expansion of functional HSCs. Telomeres are particularly sensitive to such damage because they are fragile sites in the genome. As HSCs lose telomeric DNA with each cell division, which ultimately limits their replicative potential, HSCs therefore require a protective mechanism to prevent DNA damage response (DDR) at telomeres in order to maintain their function.

The shelterin complex - which contains six subunit proteins, TRF1, TRF2, POT1, TIN2, TPP1, and RAP1 - has a crucial role in the regulation of telomere length and loop structure, as well as in the protection of telomeres from DDR signaling pathways such as ATR. Protection of telomeres 1 (POT1) binds to telomeric single-stranded DNA (ssDNA) and thereby prevents ATR signaling. Human shelterin contains a single POT1 protein, whereas the mouse genome has two POT1 orthologs, Pot1a and Pot1b, which have different functions at telomeres. Pot1a is required for the repression of DDR at telomeres. In contrast, Pot1b is involved in the maintenance of telomere terminus structure. It has recently been shown that shelterin components TRF1, Pot1b, and Tpp1 critically regulate HSC activity and survival. However, due to embryonic lethality in Pot1a knockout mice, the role of Pot1a in maintaining HSC function is still unclear and it is not known if POT1/Pot1a has a non-telomeric role in HSC regulation and maintenance.

Here, we found that Pot1a regulates HSC activity by inhibiting ATR-dependent telomeric DNA damage, and thereby protecting cells from associated apoptosis. These results indicate that the formation of the shelterin complex at the telomeric region is important to Pot1a mediated maintenance of HSC activity. However, in addition to this telomeric role we have also identified a novel non-telomeric role, preventing the production of reactive oxygen species (ROS). Due to these protective functions, we find that treatment with exogenous Pot1a maintains HSC self-renewal and function ex vivo and improves the activity of aged HSCs. This new non-telomeric role is particularly interesting since reduction of ROS is thought to be crucial in inhibiting global DNA damage in HSC in culture.

In addition to its role in protecting against stress we also found that Pot1a has a central role in regulating stem cell activity during aging. We observed that expression of Pot1a is lost during aging, and this loss results in the accumulation of DNA damage, alterations in metabolism, and an increase in ROS production, which in turn compromises aged HSC function. However, we observed that this decline is reversible: remarkably ex vivo treatment of aged HSCs with recombinant POT1a is able to re-activate aged HSCs. Since Pot1a overexpression inhibited the expression of Mtor and Rptor in aged HSCs, the regulation of mTOR signaling by Pot1a may participate in this re-activation of aged HSC function.

Although the precise mechanisms by which this functional improvement occurs have yet to be fully determined, our results indicate that exogenous Pot1a can both prevent telomeric and non-telomeric DNA damage and inhibit ROS production, thereby inducing a more potent immature phenotype in aged HSCs upon ex vivo culture. It will be interesting to clarify how these mechanisms are related to one another and determine, for example, whether telomere insufficiencies precede metabolic changes and ROS production or vice versa.

There Will be Many More Approaches to the Destruction of Senescent Cells

Targeted removal of senescent cells is a narrow form of rejuvenation, reversing one of the causes of degenerative aging. A variety of different approaches are in clinical development: targeting standard cell destruction techniques based on gene expression inside cells, as illustrated by the Oisin Biotechnologies method; various antibodies that bind to surface characteristics of senescent cells to induce immune cells to destroy them; and numerous small molecule drug candidates to target portions of the cellular mechanisms that either encourage or prevent cell self-destruction.

Senescent cells are primed for the programmed cell death process of apoptosis, and the overwhelming majority follow that path. The few that linger are the problem, but there are many points in the mechanisms of apoptosis that might be targeted to push them over the edge. A few have been discovered and demonstrated, such as the Bcl-2 family, the interaction between FOXO4 and p53, and HSP90, but the research community has only started in earnest on this line of work in the past couple of years. Initial successes to date will encourage greater efforts in the years ahead. The research here is an example of the type, in that it is a more detailed consideration of how cells choose between continued senescence and self-destruction that points out a new potential target by which that choice can be swayed in either direction.

DNA damage is a threat to genome integrity and its protection relies on the tumor protein, p53, signaling pathway response to the threat. The activity of the p53 pathway involves several feedback loops that control phosphorylated p53 concentration levels and can influence in different ways the expression of gene sets that lead to specific cell fates. In general, positive feedback loops are associated with cell fate stabilization and negative feedback loops with reversible cell fates. Under DNA damage the cell cycle is arrested at checkpoints activating the p53 pathway dynamics, in the case of light DNA damage an oscillatory dynamics is observed while for heavy damage, senescence (permanently cell cycle arrested cells) or apoptosis pathways are triggered.

Experimental and theoretical attempts to describe the oscillatory and apoptotic phenotypes are in progress, but in the case of senescence more investigations are required. Recently, an experiment confirmed a correlation between the DNA damage level induced by the anti-cancer drug etoposide with a switch in the p53 pathway behavior. For low concentrations of the drug culture cells present an oscillatory phenotype and few cell deaths, while for high concentrations there are arrested cells, no oscillations, and many cell deaths.

The onset of senescence is associated mainly with the upregulation of the cell cycle inhibitors pRB, p21, and/or the senescence DNA locus CDKN2A. MicroRNAs (miRNAs) can also regulate the cell cycle. For example, microRNAs can form feedback loops with p53. MiRNAs are small noncoding regulatory RNA molecules that target specific messenger RNAs (mRNAs) to repress their translation. A recent experimental study confirmed that miR-16, whose expression is regulated by p53, mediates the fate between senescence or apoptosis through p21. By changing miR-16 expression level the authors observed a phenotype change from senescence to apoptosis in cells. These experimental observations provide a basis for understanding how the p53 pathway dynamics is determined by repairable or irreparable DNA damage, and how perturbations of miR-16 can allow the control of cell fate.


Cellular Senescence in Chronic Kidney Disease

There is good evidence for the growing number of senescent cells present in old tissues to be an important root cause of fibrosis, the breakdown of normal regenerative processes that results in scar-like structures in place of functional tissue. Chronic kidney disease is one of a number of age-related condition driven by fibrosis, all of which presently lack effective forms of treatment, capable of significantly turning back the progression of fibrosis. Fortunately, change is coming: researchers are exploring the link between fibrotic diseases and cellular senescence with an eye to producing new classes of treatment. Numerous approaches to the targeted removal of senescent cells are presently under development. The first and simplest of them are already entering human trials. I expect to see considerable progress in the treatment of fibrosis in the years ahead.

The continuous accumulation of senescent cells leads to the age-related deterioration of vital organs and thus constitutes an organism's ageing process. Correspondingly the therapeutic removal of senescent cells can improve health and prolong lifespan. Compared with young people, the elderly population not only is more susceptible to kidney damage but also shows more severe clinical manifestations and a lower likelihood of recovery of renal function. Chronic kidney disease (CKD) is increasingly being accepted as a type of renal ageing. Along with the process of ageing, the kidney shows certain types of changes for which specific findings are lacking. The ageing kidney and CKD share a great number of similarities in both structural and functional changes.

CKD is a frequent independent risk factor for renal failure and other age-related diseases. CKD is a complex pathological process mainly involving oxidative stress, inflammation, autophagy, apoptosis, and epigenetics. Recently, cellular senescence has become an increasingly popular and extensively studied topic because of its role in the occurrence and development of CKD. In CKD, the expression levels of senescence-associated β-galactosidase (SA-β-gal) and cell cycle inhibitor p16 protein were significantly increased in the glomeruli, tubules and interstitium, suggesting that the process of cellular senescence occurs in CKD. Many factors involved in the progress of CKD, such as urinary toxins, infections, dialysis treatment, and excessive activation of the renin-angiotensin system, can cause diverse types of DNA damage response (DDR) and accelerate the ageing process. The role of cellular senescence in CKD cannot be ignored.

When cells become senescent, they remain metabolically active and undergo widespread gene expression changes, secreting certain factors and changing the surrounding environment. This is the senescence-associated secretory phenotype (SASP), consisting of all types of cytokines, chemokines, growth factors, and proteases. In the course of kidney diseases, several cell types in the kidney experience cellular senescence and secrete a large number of factors that are collectively defined as the CKD-associated secretory phenotype (CASP). It has been demonstrated that CASP and SASP have prominent similarities, which may act as an essential medium mediating the interaction between CKD and cellular senescence.

Although there is a striking resemblance between SASP and CASP in terms of their features of up-regulation and the species involved, there remain many gaps in the understanding of the complex role of cellular senescence and SASP in CKD and other age-related diseases. It is beneficial to establish their mechanisms in the pathogenesis and progression of CKD. Therefore, the common process of cellular senescence and SASP is considered a treatment target for CKD and other age-related diseases.


Loss of Lipid Chaperones Mimics Some Aspects of Calorie Restriction

The research I'll note today involves genetic knockout of fatty acid-binding proteins in mice, something that appears to slow the development of metabolic disorders associated with excess fat tissue and aging - there is a lot more funding for investigation of the former cause as opposed to the latter cause, sadly. The work is, I think, chiefly interesting for mimicking some of the cellular effects of calorie restriction, while preventing some degree of the metabolic decline that accompanies aging, but achieving all of this without either extending life or improving the other usual functional measures of aging: loss of strength, cognitive decline, and so forth. In principle that sort of result should be quite hard to achieve, and indeed I can think of few lines of research in which this happens with any reliability in short-lived species such as mice. They are sensitive to environmental and genetic interventions, with very plastic life spans in comparison to those of longer-lived species such as our own. Anything that constitutes a significant improvement to health should also extend life.

Extending the duration of measures of health without extending life span is hard precisely because aging is determined by cell and tissue damage, a consequence of that damage, just like the decline of any complex machinery. There are only a few options when it comes to how to proceed: fix the root cause damage, try to compensate for loss of function by adding more capacity, or try to prevent secondary effects that result from the primary damage. Medicine to date has focused on the latter two options, which is precisely why it produces only marginal, incremental benefits. Making a damaged machine work well without repairing the damage is exactly as challenging as it sounds.

The genetic intervention carried out by the researchers in this paper has the look of a method of preventing secondary effects, some of those resulting from weight gain and fat tissue dysfunction in aging, by interfering in the processing of fats. That is no doubt an overly simplistic consideration. For example, we know that simple surgical removal of visceral fat significantly extends life span in mice, and yet the genetic approach here, that reduces weight gain, has no such outcome. A first thought is that it is possible that removal of fatty acid-binding proteins is causing harm in other areas of biochemistry, and thus shortening life even as it helps on the metabolic front. So while the researchers discuss their data as evidence of a decoupling of metabolic health and life span, and make a fair case, it may or may not be what is happening under the hood.

Targeting 'lipid chaperones' may hold promise for lifelong preservation of metabolic health

Scientists found that mice that lack fatty acid-binding proteins (FABPs) exhibit substantial protection against obesity, inflammation, insulin resistance, type 2 diabetes, and fatty liver disease as they age compared with mice that have FABPs. However, this remarkable extension of metabolic health was not found to lengthen lifespan. FABPs are escort proteins or "lipid chaperones" that latch onto fat molecules, transport them within cells, and dictate their biological effects. Previous work found that when FABP-deficient mice were fed high-fat or high-cholesterol-containing diets, they did not develop type 2 diabetes, fatty liver, or heart disease.

Metabolic health typically deteriorates with age, and researchers believe that this contributes to age-associated chronic diseases and mortality. Studies have shown that high-calorie diets impair metabolism and accelerate aging; conversely, calorie restriction has been shown to prevent age-related metabolic diseases and extend lifespan. In the new study, researchers examined metabolic function in multiple cohorts of FABP-deficient mice throughout their life. They found that FABP deficiency markedly reduced age-related weight gain, inflammation, deterioration of glucose tolerance, insulin sensitivity, and other metabolic malfunctions. This effect was more strongly observed in female than male mice. Surprisingly however, they did not find any improvement to lifespan or preservation of muscular, cognitive, or cardiac functions with age.

The researchers saw striking similarities between the alterations in tissue gene expression and metabolite signatures in the genetic model of FABP-deficiency developed for this study and the alterations that occur due to calorie restriction. The findings suggest that it may be possible to mimic part of the metabolic benefits of calorie restriction by targeting FABPs. In addition, by examining the molecular differences between these models, it may also be possible to identify other pathways that contribute to longer life span or alternative strategies to prevent metabolic diseases.

Uncoupling of Metabolic Health from Longevity through Genetic Alteration of Adipose Tissue Lipid-Binding Proteins

In this study, we have shown that the lipid chaperones FABP4/FABP5 are critical intermediate factors in the deterioration of metabolic systems during aging. Consistent with their roles in chronic inflammation and insulin resistance in young prediabetic mice, we found that FABPs promote the deterioration of glucose homeostasis; metabolic tissue pathologies, particularly in white and brown adipose tissue and liver; and local and systemic inflammation associated with aging. A systematic approach, including lipidomics and pathway-focused transcript analysis, revealed that calorie restriction (CR) and Fabp4/5 deficiency result in similar changes to the adipose tissue metabolic state, specifically enhanced expression of genes driving de novo lipogenesis and non-esterified fatty acids accumulation. Furthermore, CR was associated with reduced FABP4 in circulation, providing a potential molecular mechanism underlying its metabolic benefit.

The extension of metabolic health by Fabp deficiency is long-lasting even in aged female mice. However, despite the remarkable protection in glycemic control, insulin sensitivity, inflammation, and tissue steatosis in Fabp-deficient mice, we did not observe any change in the lifespan curves. We also did not detect preservation of cardiac, muscular, and cognitive functions. In females, there was even a mild decline in cardiomuscular function associated with Fabp deficiency during aging. These observations support the concept that, in higher organisms, significant improvements in metabolic tissue inflammation, metabolic tissue integrity, and systemic metabolic homeostasis may not necessarily lead to increased longevity.

Our studies with Fabp-deficient mice now provide genetic evidence in animal models that prolonged metabolic health, particularly glucose and lipid homeostasis, may be uncoupled from lifespan and maintenance of cardiac, muscular, and cognitive systems, which partially recapitulates the human pathophysiology observed during intensive glycemic control. Furthermore, it is intriguing that there is a considerable overlap between the unique lipidomic profile, especially in adipose tissue, of Fabp-deficient animals with those that have been subject to CR. Future studies exploring the similarities and distinctions between these models in multiple sites may provide additional insights into specific pathways and their regulation of healthspan and lifespan. Further exploration of the disconnect between metabolic health and longevity may also shed light on alternative therapeutic approaches against diabetes and possibly other metabolic diseases that are associated with aging as a risk factor.

The Genre of Popular Science Articles on Treating Aging that Fail to Mention SENS Rejuvenation Research Programs

This popular science article on efforts to treat aging as a medical condition is a particularly good example of the type that fail to mention SENS rejuvenation research and any related efforts that involve repair of the cell and tissue damage that causes aging. This one even omits any mention of senolytics, the rapidly broadening efforts to clear senescent cells that are supported by increasingly robust evidence, which has to be a deliberate omission in any overview of the current state of the field. The rise of senolytics and the current enthusiasm for study of senescent cells is very hard to miss. Why do authors do this? What is the prejudice that leads them to focus on marginal, challenging efforts that haven't made significant progress towards practical therapies, such as work on calorie restriction and calorie restriction mimetics? This author is clearly capable of finding sensible things to say about many of the topics that are covered, which makes it more of a mystery.

As researchers work to develop and test ways to slow aging, they will first look to create treatments intended for people in their 50s and 60s, when chronic diseases often start to set in. Studies evaluating those treatments, some of which are already planned (most notably the trial for metformin), should only take a few months or years, measuring secondary indicators like frailty instead of death itself to ensure their efficacy. Eventually, there might be drugs for people to start taking when they're even younger. But giving pharmaceuticals to healthy people is a hard sell. Without extensive long-term clinical trials, it's impossible to anticipate how the decades-long use of an anti-aging drug will affect other aspects of long-term health. There will almost inevitably be some side effects, and the public will have to wade through discussions of whether or not it's worth it. There are people who question whether the clinical trials needed to prove the safety and efficacy of such therapies are even ethical.

These issues hint at a deeper ideological hurdle stopping anti-aging treatments from becoming commonplace. For now, our medical system is designed to address medical conditions as they arise. Putting interventions to treat aging on the market would mean a fundamental shift in our medical system, towards preventative medicine. "We've been trained in biomedicine to focus on sickness rather than health, so that paradigm shift will take time." And to move from success in the lab to having an actual impact on human wellbeing, you need to have public opinion on your side. Social acceptance of aging interventions could pave the way for the medical shift. The field of anti-aging research suffers from a reputation problem. For decades, products running the gamut from skin creams to herbal supplements have claimed to have "anti-aging" properties, with virtually no science to back them up. "People associate our field with snake oil. That only adds to that perception that it's not rigorous." What's more, people in general are reluctant to talk about getting old and dying.

For now, researchers are still trying to get the U.S. Food and Drug Administration (FDA) onboard. As it stands now, the FDA only approves treatments for a specific medical condition. Now researchers in the field of aging are trying to convince the agency to make a separate designation for preventative medicine. From the FDA's perspective, the field of medicine built around combating aging is still in its infancy. "A question not yet answered is how many aging-related but otherwise independent diseases (coronary artery disease, dementia, sarcopenia, etc.) would need to be improved for us to consider the therapeutic effect an 'anti-aging' effect, rather than an effect on specific diseases. It is worth noting again that a drug that improved any of these conditions would be very valuable," an FDA spokesperson said. It's also still a challenge to figure out how to measure whether or not these interventions are effective.

"If the field of aging is going to move forward in having drugs to treat aging in humans, we're going to have to have an FDA-approved pipeline to do so." Having that framework in place will drive innovation, researchers claim - more research money can be allocated towards prevention, and pharmaceutical companies will work to develop new drugs that could potentially be used by the entire adult population. Though researchers don't believe there will be a special designation for anti-aging interventions anytime soon, a clear FDA pathway, plus more frank public discourse, could give the field a reputation to match the rigorous science already underway. And it seems increasingly likely that some intervention or another will emerge to keep people healthy for longer. "20 years ago, I would have said finding a way to extend the health span had a .5 percent chance of working. It's up to a 25 percent chance now, and every year it's going up."


A Small Molecule Drug that Selectively Induces Apoptosis in Cancer Cells

This cancer research is interesting for the strong resemblance it bears to current senolytic strategies to destroy senescent cells by forcing them into the programmed cell death process of apoptosis: these cells are primed for that fate, but fail to reach it on their own. The therapies used affect normal cells as well as the targeted senescent cells, but cause little impact in the healthy cells that should be spared. This same type of approach is here applied to cancerous cells, using a close relative of the pro-apoptosis targets employed for senescent cells. Considered at the high level, this makes an interesting counterpoint to the trend towards the development of precision targeting in cancer research: any method of killing cells is useful if it can be restrained to only the cells that should be killed. Therein lies the challenge, of course.

In principle it seems possible to produce a therapy that can be globally applied throughout the body but only does harm to cancerous cells - though in practice such selectivity is a sliding scale, and nothing is perfect. Causing less harm to the patient than the current standard of chemotherapy is a low bar, but conversely the effectiveness of this first attempt seems marginal. It is only slowing down cancer a little rather than fixing the problem. Still, it is only the starting point for a whole new area of exploration.

Scientists have discovered the first compound that directly makes cancer cells commit suicide while sparing healthy cells. The new treatment approach was directed against acute myeloid leukemia (AML) cells but may also have potential for attacking other types of cancers. The newly discovered compound combats cancer by triggering apoptosis - an important process that rids the body of unwanted or malfunctioning cells. Apoptosis trims excess tissue during embryonic development, for example, and some chemotherapy drugs indirectly induce apoptosis by damaging DNA in cancer cells.

Apoptosis occurs when BAX - the "executioner protein" in cells - is activated by "pro-apoptotic" proteins in the cell. Once activated, BAX molecules home in on and punch lethal holes in mitochondria, the parts of cells that produce energy. But all too often, cancer cells manage to prevent BAX from killing them. They ensure their survival by producing copious amounts of "anti-apoptotic" proteins that suppress BAX and the proteins that activate it. "Our novel compound revives suppressed BAX molecules in cancer cells by binding with high affinity to BAX's activation site. BAX can then swing into action, killing cancer cells while leaving healthy cells unscathed."

Researchers first described the structure and shape of BAX's activation site in 2008, and have since looked for small molecules that can activate BAX strongly enough to overcome cancer cells' resistance to apoptosis. The team initially used computers to screen more than one million compounds to reveal those with BAX-binding potential. The most promising 500 compounds were then evaluated in the laboratory. A compound dubbed BTSA1 (short for BAX Trigger Site Activator 1) proved to be the most potent BAX activator, causing rapid and extensive apoptosis when added to several different human AML cell lines. The researchers next tested BTSA1 in blood samples from patients with high-risk AML. Strikingly, BTSA1 induced apoptosis in the patients' AML cells but did not affect patients' healthy blood-forming stem cells.

Finally, the researchers generated animal models of AML by grafting human AML cells into mice. BTSA1 was given to half the AML mice while the other half served as controls. On average, the BTSA1-treated mice survived significantly longer (55 days) than the control mice (40 days), with 43 percent of BTSA1-treated AML mice alive after 60 days and showing no signs of AML. Importantly, the mice treated with BTSA1 showed no evidence of toxicity.


SENS Patron Fundraiser for 2017: Additional Challenge Fund Donors Sought

As has become the custom, the SENS Research Foundation will be running a year-end fundraiser in the last few months of 2017, the proceeds going to support work on the foundations of real, working rejuvenation therapies. We of the Fight Aging! community will do our part to help make it a success. Expect it to start up at the end of October or the first week of November. Last year Josh Triplett, Christophe and Dominique Cornuejols, and Fight Aging! joined forces to put up $36,000 challenge fund that matched the first year of donations made by anyone who signed up as a SENS Patron by setting up recurring monthly donations to the SENS Research Foundation. We all think it important to help build up the core of supporters who supply the regular donations that help to fund SENS research projects: the more regular donors, the less uncertain the flow of funding, something that is always a challenge for non-profit organizations. On this topic, you might recall that the initial success of the Methuselah Foundation, launched nearly fifteen years ago now, was built atop the funds and support provided by the Methuselah 300, a group of monthly donors.

For the SENS Patron challenge, we hit 85% of our target in 2016, encouraged the participation of numerous new monthly donors, and I'm pleased to say we'll be back again for another try this year, with another $36,000 pledged to challenge the community. But why stop at $36,000? If you want to make a difference to the future of human health and longevity, and want your contributions to make a sizable impact, then why not help our community fundraiser by joining in to expand the SENS Patron challenge fund? The SENS year end fundraisers have a great record when it comes to the use of challenge funds to attract new donations. Further, the SENS rejuvenation research programs that our donations have supported over the past decade or more, first at the Methuselah Foundation, and then at the SENS Research Foundation, have a proven track record of enabling active clinical development of therapies, such as in areas relating to mitochondrial damage, senescent cells, and clearance of cellular waste. More of that sort of thing will be rolling out later this year and early next year, so keep an eye out for new announcements on that front.

While very welcome, this concrete progress enabled by our support does only cover the first set of tasks, the first set of research areas and potential therapies to be unblocked and to reach fruition. There is more yet to be done, and philanthropy is still needed to accomplish these goals - to rescue and expand areas of research that are still languishing, but that have the potential to be just as exciting and influential in the treatment of aging as, say, the clearance of senescent cells has become in recent years. Six years ago senescent cells were a disregarded backwater for everyone except SENS advocates and a few determined research teams who struggled to find funding. Change can be rapid when it finally takes off, and our support for the SENS Research Foundation is a very important, necessary foundation for that change. There are few other areas of philanthropy where one can help to generate such enormous, important changes in the capacity of medical science. The defeat of aging lies somewhere ahead, a improvement in the human condition more profound than any other yet achieved through medicine. We are helping to make it happen.

So give it some thought: there is a warm welcome waiting for any new challenge fund donors willing to step up and grow this year's SENS Patron fundraiser - please contact us with questions or offers of support.

The Prospect of Engineering Better Gut Bacteria

Scientists are finding that gut bacteria have some influence on natural variations in longevity; not as much as exercise or calorie intake - though they they may mediate some of those benefits - but enough to be interesting to the research community. The distribution of species changes with age, for example, and gut bacteria interact with the immune system to produce inflammation and other effects. A range of other specific mechanisms will probably emerge in the years ahead as more research teams join the investigation. I suspect that this is one of those parts of the field that will diminish in importance as rejuvenation therapies after the SENS model take off: the size of the effects are just not all that interesting in a world in which it becomes possible to reliably add ten or more healthy years with treatments to clear senescent cells, remove glucosepane cross-links, and so forth. Still, I think you'll have to agree that the prospect of engineering better, more beneficial gut bacteria, as outlined here, is certainly interesting from a technical and future scope of options perspective, setting aside the question of the size of likely near-term benefits for a moment.

We have a symbiotic relationship with the trillions of bacteria that live in our bodies - they help us, we help them. It turns out that they even speak the same language. And new research suggests these newly discovered commonalities may open the door to "engineered" gut flora who can have therapeutically beneficial effects on disease. In a double-barreled discovery, researchers found that gut bacteria and human cells, though different in many ways, speak what is basically the same chemical language, based on molecules called ligands. Building on that, they developed a method to genetically engineer the bacteria to produce molecules that have the potential to treat certain disorders by altering human metabolism. In a test of their system on mice, the introduction of modified gut bacteria led to reduced blood glucose levels and other metabolic changes in the animals.

The method involves the lock-and-key relationship of ligands, which bind to receptors on the membranes of human cells to produce specific biological effects. In this case, the bacteria-derived molecules are mimicking human ligands that bind to a class of receptors known as GPCRs, for G-protein-coupled receptors. Many of the GPCRs are implicated in metabolic diseases and are the most common targets of drug therapy. And they're conveniently present in the gastrointestinal tract, where the gut bacteria are also found. The researchers engineered gut bacteria to produce specific ligands, N-acyl amides, that bind with a specific human receptor, GPR 119, that is known to be involved in the regulation of glucose and appetite, and has previously been a therapeutic target for the treatment of diabetes and obesity. The bacterial ligands they created turned out to be almost identical structurally to the human ligands.

Among the advantages of working with bacteria is that their genes are easier to manipulate than human genes and much is already known about them. "All the genes for all the bacteria inside of us have been sequenced at some point. The biggest change in thought in this field over the last 20 years is that our relationship with these bacteria isn't antagonistic. They are a part of our physiology. What we're doing is tapping into the native system and manipulating it to our advantage. This is a first step in what we hope is a larger-scale, functional interrogation of what the molecules derived from microbes can do."


Rejuvenation Therapies will Grant Additional Healthy Years, Not Years of Disability

When it comes to persuading the public to support work on the development of rejuvenation therapies, it sometimes seems that, even after years of effort, we're still somewhat stuck at the point of convincing people that therapies to push back aging and extend life will result in more healthy years rather than an extended period of ever-increasing decrepitude. The knee-jerk response to the goal of life extension is to imagine an eking out of the period of pain, suffering, and ill-health at the end of life. Obviously, this isn't all that attractive a prospect. Yet it was never the goal: therapies that successfully treat the causes of aging, repairing the accumulated cell and tissue damage that lies at the root of aging, will produce rejuvenation and additional healthy years. Despite a couple of decades of messaging from the scientific community and advocates for healthy life extension, all telling the public that extended health and youth is the goal, we still run headlong into this false expectation of an extended old age of sickness and diminishment.

Whenever the topic of increasing human lifespan is discussed the concern is sometimes raised that a longer life would mean a life spent frail and decrepit. This is sometimes known as the Tithonus error and shows a fundamental misunderstanding of the aims of rejuvenation biotechnology. Tithonus, as the story goes, was granted immortality by Zeus, but the father of the gods had not also granted eternal youth. Tithonus never died, but he kept aging like any other mortal; eventually, he was so decrepit, disease-ridden, and demented that his life had become unbearable.

This type of concern is sometimes raised by those who don't have a clear picture of rejuvenation biotechnologies and fear that an extended period of frailty and decrepitude may be what scientists are after. Thankfully, quite the opposite is true, and, in fact, Tithonus' grim fate is physically impossible. In the fanciful realm of gods and myths, anything goes and the impossible becomes mundane, but in the real world, neither Zeus nor anyone else could make you live forever without eliminating or obviating the aging process. This is because death is nothing but the result of a critical failure of your inner workings - if you died, it means something crucial in your body stopped functioning properly and thus triggered a cascade of failure whose ultimate consequence was your death.

In particular, in the case of death by old age, the critical failure is caused by one or several pathologies resulting from a life-long process of damage accumulation. This process is slow but insidious, and it starts speeding up considerably after middle age. Frailty, weakness, and all the notorious diseases of old age are its primary consequences and are due to the fact that accumulated damage prevents your body from functioning at its best; when the damage is extensive enough, your body cannot function at all anymore. Living forever while aging forever would thus be equivalent to a human-made machine still functioning despite all of its mechanisms being eventually completely broken, which is a contradiction in terms.

A very small-scale version of Tithonus' myth does actually take place as a consequence of present-day geriatric medicine. Geriatric medicine focuses on treating the symptoms of age-related diseases rather than their causes, with the result of modestly improving patient health and lifespan - in other words, although with the best intentions, geriatrics does prolong the time patients spend in decrepitude. They live a little longer because mitigating the symptoms slightly postpones the inevitable, but as age-related damage keeps accumulating, eventually the point of no return is reached. It's a bit like trying to empty a river using a coffee mug.

Interventions for different types of age-related damage - such as senolytics for senescent cell clearance, enzyme replacement therapy to dispose of intracellular waste, and AGE-breaking molecules to eliminate extracellular cross-links - are currently being developed, and some are even undergoing human clinical trials. The aim of rejuvenation biotechnology is neither extending frailty nor achieving a modest amelioration of an elderly patient's health; rather, the goal is to comprehensively address age-related damage to allow people to maintain youthful levels of health for as long as they live, however long that may be.


More Evidence for Hippo Pathway Blockade to be a Road to Enhanced Regeneration

In the research I'll point out today, scientists interfere with the Hippo signaling pathway in mouse heart tissue to spur greater regeneration following a heart attack. The pathway controls cell proliferation, making it the target of attention from the regenerative medicine research community. Today's paper is one of a number of approaches that target this pathway: a fair few groups are involved in work on enhanced regeneration that in some way touches upon Hippo activity. When looking back at a sampling of the past few years, there are studies using microRNAs to interdict one part of the pathway, others uncovering regulatory RNAs that adjust this complex machinery at a different point, work on mapping links between Hippo and other pathways known to be involved in regeneration, and a paper reporting that suppression of the Hippo pathway makes the liver more regenerative by allowing mature cells to dedifferentiate into progenitor cells.

It is not unreasonable to expect there to be manipulations that enhance regeneration. Evolution doesn't optimize for individual convenience. There are many fairly similar species with broadly different regenerative capacities that evolved from a common ancestor. Somewhere there must be changes of a comparatively modest scope that change the degree to which tissues maintain themselves. "Modest scope" in the context of cellular biochemistry may still be ferociously complex as an implementation project for medical technology, but the examples found to date are promising, even taking into account the potential risk that any specific approach to producing increased regenerative activities may significantly increase the risk of cancer.

Beyond stem cell therapies and the machinery surrounding the Hippo pathway, we can also point to adjustment of macrophage polarization and levels of cellular senescence as ways to improve baseline human regeneration or reverse some of the declines that take place with age. As an aside on that latter topic, one can draw links between cellular senescence and Hippo pathway activity, and given the recent understanding that senescent cells disrupt regeneration and are a significant cause of fibrosis, it is very interesting to see that the researchers here find that disabling Hippo pathway activity reduces fibrosis following injury in the heart. Researchers are also narrowing down some of the important differences between mammals that cannot regrow limbs and species such as salamanders and zebrafish that can. It is a little early to say where this will all end up a decade or two from now, but the advent of multiple methods of incrementally improving regenerative capacity for short period of time, so as to evade increased cancer risk, seems a safe prediction.

Scientists reverse advanced heart failure in an animal model

Researchers have discovered a previously unrecognized healing capacity of the heart. In a mouse model, they were able to reverse severe heart failure by silencing the activity of Hippo, a signaling pathway that can prevent the regeneration of heart muscle. 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 progressively weakens; most people who had a severe heart attack will develop heart failure.

"One of the interests of my lab is to develop ways to heal heart muscle by studying pathways involved in heart development and regeneration. In this study, we investigated the Hippo pathway, which is known from my lab's previous studies to prevent adult heart muscle cell proliferation and regeneration. When patients are in heart failure there is an increase in the activity of the Hippo pathway. This led us to think that if we could turn Hippo off, then we might be able to induce improvement in heart function."

"We designed a mouse model to mimic the human condition of advanced heart failure. Once we reproduced a severe stage of injury in the mouse heart, we inhibited the Hippo pathway. After six weeks we observed that the injured hearts had recovered their pumping function to the level of the control, healthy hearts." The researchers think the effect of turning Hippo off is two-fold. On one side, it induces heart muscle cells to proliferate and survive in the injured heart, and on the other side, it induces an alteration of the fibrosis. Further studies are going to be needed to elucidate the changes observed in fibrosis.

Hippo pathway deficiency reverses systolic heart failure after infarction

Mammalian organs vary widely in regenerative capacity. Poorly regenerative organs such as the heart are particularly vulnerable to organ failure. Once established, heart failure commonly results in mortality. The Hippo pathway, a kinase cascade that prevents adult cardiomyocyte proliferation and regeneration, is upregulated in human heart failure. Here we show that deletion of the Hippo pathway component Salvador (Salv) in mouse hearts with established ischaemic heart failure after myocardial infarction induces a reparative genetic program with increased scar border vascularity, reduced fibrosis, and recovery of pumping function compared with controls.

Using translating ribosomal affinity purification, we isolate cardiomyocyte-specific translating messenger RNA. Hippo-deficient cardiomyocytes have increased expression of proliferative genes and stress response genes, such as the mitochondrial quality control gene, Park2. Genetic studies indicate that Park2 is essential for heart repair, suggesting a requirement for mitochondrial quality control in regenerating myocardium. Gene therapy with a virus encoding Salv short hairpin RNA improves heart function when delivered at the time of infarct or after ischaemic heart failure following myocardial infarction was established. Our findings indicate that the failing heart has a previously unrecognized reparative capacity involving more than cardiomyocyte renewal.

Excess Visceral Fat Tissue Raises Cancer Risk

One of the many detrimental consequences of carrying excess fat tissue is an increased risk of cancer. Visceral fat generates chronic inflammation in addition to other forms of metabolic disruption, and that inflammation speeds the development and progression of all of the common age-related conditions, cancer included. The epidemiological research noted here is one way of looking at the numbers behind this relationship. When considering the number of people who are harming their health by being overweight, it is interesting to note the fact that progress in medical technology is still keeping pace to reduce mortality in later life, even while using poor strategies that do not address the root causes of either aging or fat-associated metabolic dysfunction, but instead try to compensate for or tinker with the later disease state.

Being overweight or obese are associated with increased risk of 13 types of cancer. These cancers account for about 40 percent of all cancers diagnosed in the United States in 2014, according to the latest Vital Signs report by the Centers for Disease Control and Prevention (CDC). The Vital Signs report analyzed 2014 cancer incidence data from the United States Cancer Statistics report and reviewed data from 2005 to 2014 to determine trends. About 630,000 people in the U.S. were diagnosed with a cancer associated with being overweight or obese in 2014. About 2 in 3 occurred in adults 50- to 74-years-old. Cancers associated with being overweight or obese, excluding colorectal cancer, increased 7 percent between 2005-2014. Colorectal cancer decreased 23 percent, due in large part to screening. Cancers not associated with being overweight or obese decreased 13 percent.

In 2013-2014, about 2 out of 3 adults in the U.S. were overweight (defined as having a body mass index of 25-29.9 kg/m2) or had obesity (having a body mass index of 30 kg/m2 and higher). The body mass index (BMI) is a person's weight (in kilograms) divided by the square of the person's height (in meters). Many people are not aware that being overweight and having obesity are associated with some cancers. The International Agency for Research on Cancer (IARC) has identified 13 cancers associated with being overweight or obese: meningioma, multiple myeloma, adenocarcinoma of the esophagus, and cancers of the thyroid, postmenopausal breast, gallbladder, stomach, liver, pancreas, kidney, ovaries, uterus, colon and rectum (colorectal).


Using Historical Basketball Player Records to Investigate Height and Longevity

Height is a matter of importance to observers of basketball, so the records of professional players from past decades can be used to investigate the effects of height on longevity. Evidence to date strongly supports an inverse relationship in humans: the taller you are, the shorter your life expectancy, though the size of this effect is unclear and debated. The underlying reasons are thought to involve cancer risk, as taller people have more cells and thus more chances for something to go wrong, as well as lung function, and the influence of growth hormone metabolism on the pace of aging. To what degree does all of this matter? The ultimate goal of rejuvenation research programs such as those of the SENS Research Foundation is to make all of these interesting variations in human health and longevity entirely irrelevant: when medicine can turn back the causes of aging to grant additional decades of life, it will not in fact matter that your genetic heritage adds or removes a few years of life expectancy.

The premise that larger body size leads to reduction in lifespan longevity has generally been substantiated through scientific research over the past 40 years. For example, research suggests smaller body size is generally better for one's health, and is supported by robust cross-cultural findings of average lifespan reduction with increasing height observed in groups such as deceased American male veterans, French males and females who died before the year 1861 and males born in Sardinia, Italy between 1866 and 1915. While the biological reason for the relationship between height and lifespan longevity in humans is not yet fully understood, it is difficult to ignore the potential profound effect of genetics on lifespan longevity. A study on 8,006 American men of Japanese ancestry found height was positively associated with mortality, and perhaps of more interest, was the first to conclusively link the "longevity gene" FOX03 to smaller body size and greater lifespan longevity in humans.

Although a sizeable amount of evidence suggests that larger body size independently reduces longevity, it also important to recognize confounders of this relationship that affect biological parameters independent of body size characteristics, such as differences in genotypes, socioeconomic status (SES), education, medical care, relative weight, hygienic practices, nutrition, and lifestyle choices such as engaging in regular exercise and avoiding smoking. Further, it has been suggested that height generally explains less than 10% of the proportion of variance regarding longevity, and researchers surmise that the lack of consensus on the degree to which height affects longevity is likely due to the impact of these extraneous variables.

If height indeed influences longevity independently, deceased professional basketball players represent a promising group to further investigate this phenomenon in given their general exceptional height and relative homogeneity of other confounders such as affluence (particularly in the more recent decades), where the higher SES/social status may result in less confounding by factors such as ethnicity. We hypothesized that when adjusting for birth decade, exceptionally taller players will have died at relatively younger ages. The population of this study was comprised of living and deceased players who played in the National Basketball Association (NBA), debut between 1946-2010, and/or the American Basketball Association (ABA), debut between 1967-1976.

Overall, 3,901 living and deceased players were identified and had a mean height of 197.78 cm, and of those, 787 former players were identified as deceased with a mean height of 193.88 cm. Descriptive findings indicated that the tallest players (top 5%) died younger than the shortest players (bottom 5%) in all but one birth decade (1941-1950). Similarly, survival analyses showed a significant relationship between height and lifespan longevity, where taller players had a significantly higher mortality risk compared to shorter players (hazard ratio: 1.30). As many players have superior height compared to the age- and sex-matched average height of the US general population, there appears to be a curvilinear relationship between height and longevity where the magnitude of mortality risk decreases past a certain threshold. However, smaller sample sizes in the younger players may have been driving this effect. From a general population perspective, it is unclear whether there is a threshold for the apparent longevity benefits from having smaller body size.


Towards the Recognition of Aging as a Treatable Medical Condition

In recent years numerous groups have made a start on the long road of changing the public view of aging, from considering it a normal state to considering it a pathological state. To have it recognized as a harmful medical condition that can in principle be treated - that medical technologies can be developed for this purpose soon enough to matter. This is a process of unofficial advocacy and persuasion on the one hand, to change minds and educate people, but on the other there is also a strong component of formalism, of working with regulatory definitions. Medical research and development is, sadly, heavily regulated. The structure of regulation shapes the ability to raise funding and carry out meaningful work on the creation of means to treat aging. The US FDA, for example, doesn't recognize aging as a condition that can or should be treated, though the first cracks in that position are taking shape in the form of the TAME metformin trial. Yet the current position still means that efforts to treat aging struggle to find the necessary resources to proceed.

Since most agencies base their regulation on the World Health Organization's (WHO's) International Statistical Classification of Diseases and Related Health Problems, with ICD-11 being the latest edition in the process of being finalized, some initiatives have focused on placing aging into that document as a formally defined disease. This would be in a definitive way, unlike the one or two present entries that might be interpreted as referring to aging, given the right light, but in practice are disregarded. Whether or not aging is called a disease is a matter of semantics, and in this the powers that be and the fellow in the street both seem quite willing to designate numerous specific aspects of aging as diseases, with fashion rather than logic dictating what is a portion of normal aging and what is a disease. But when it comes to the ICD, these semantics drive policy and regulation. That has material consequences, more is the pity. Things would move forward a lot more rapidly absent the heavy restrictions placed upon medical research and development, I feel. There are already ample laws covering fraud and harm in the conduct of any human action. Why all the rest layered on top? It feels like control for the sake of control, institutions perpetuating themselves simply because they can.

Ultimately, rules follow opinions, or at least those opinions prevalent among the rule-making class. They are swayed by the zeitgeist. So a shift of public opinion and awareness about aging - and about the advent of near-future rejuvenation therapies that actually work - is important. In the ideal world, the fellow in the street would think of aging in the same way as he thinks of cancer: that someone should do something about it, because it is a painful, undesirable thing, and it is both good and generous to help the laboratories and clinics and funding institutions to make progress on this front. As things stand, we're a fair way from that goal, unfortunately. It will be very interesting to watch how matters progress in public opinion should the first human trials of senolytics produce good data and proof of effectiveness. Meanwhile, there are people toiling in the maze of regulatory definition, trying to carve out a path, a way to adjust the present stifling system of rules and statements:

Recognizing Degenerative Aging as a Treatable Medical Condition: Methodology and Policy

Given the rapid aging of the world population and the accompanying rise of aging-related diseases and disabilities, the task of increasing the healthy and productive period of life becomes an urgent global priority. It is becoming increasingly clear that in order to accomplish this purpose, there is an urgent need for effective therapies against degenerative aging processes underlying major aging related diseases, including heart disease, neurodegenerative diseases, type 2 diabetes, cancer, pulmonary obstructive diseases.

One facilitating possibility may be to recognize the degenerative aging process itself as a medical problem to be addressed. Such recognition may accelerate research, development and distribution in several aspects: 1) the general public will be encouraged to actively demand and intelligently apply aging-ameliorating, preventive therapies; 2) the pharmaceutical and medical technology industry will be encouraged to develop and bring effective aging-ameliorating therapies and technologies to the market; 3) health insurance, life insurance and healthcare systems will obtain a new area for reimbursement practices, which will encourage them and their subjects to promote healthy longevity; 4) regulators and policy makers will be encouraged to prioritize and increase investments of public funds into aging-related research and development; 5) scientists and students will be encouraged to tackle a scientifically exciting and practically vital problem of aging.

Yet, in order for the degenerative aging process to be recognized as a diagnosable and treatable medical condition and therefore an indication for research, development and treatment, a necessary condition appears to be the development of evidence-based diagnostic criteria and definitions for degenerative aging. Such commonly accepted criteria and definitions are currently lacking. Yet without such scientifically grounded and clinically applicable criteria, the discussions about "ameliorating" or even "curing" degenerative aging processes will be mere slogans. Such criteria are explicitly requested by major regulatory frameworks, such as the International Classification of Diseases (ICD), the Global Strategy and Action Plan on Ageing and Health (GSAP), the European Medicines Agency (EMA), the US Food and Drug Administration (FDA). Nonetheless, nobody has yet done the necessary work of devising such criteria.

"Senility," tantamount to degenerative aging, is already a part of the current ICD-10 listing. In the draft ICD-11 version (to be finalized by 2018), the code MJ43 refers to "Old age," synonymous with "senescence" and "senile debility." The nearly 40 associated index terms in the ICD-11 draft also include "ageing" itself, "senility," "senile degeneration," "senile decay," "frailty of old age," and others. Still, the current definitions, such as "senility," seem to be rather deficient in terms of their clinical utility. This may be the reason why "senility" has been commonly considered a garbage code, e.g. in the Global Burden of Disease (GBD) studies. The reason "senility" has been considered a garbage code is likely because there have been no reliable, clinically applicable and scientifically grounded criteria for diagnosis of "senility" or of "senile degeneration." Consequently, there could be no official case finding lists. Hence, in order to successfully use this code in practice, it appears to be necessary to be able to develop formal and measurable, biomarkers-based and function-based diagnostic criteria for "senility" or "senile degeneration," as well as measurable agreed means to test the effectiveness of interventions against this condition.

Crowdfunding a Portuguese Translation of Ending Aging

Ending Aging: The Rejuvenation Breakthroughs That Could Reverse Human Aging in Our Lifetime, written by Aubrey de Grey and Michael Rae of the SENS Research Foundation, has been translated into a number of languages since its first release nearly a decade ago, but Portuguese is not yet one of them. A couple of Brazilian members of our community are hoping to change that, and are currently crowdfunding the necessary resources to achieve this goal. Translating scientific texts is always a degree more challenging than the usual fare, but helping to further spread the SENS view of aging is a worthy cause: this is a detailed plan for the creation of rejuvenation therapies that work by repairing the damage that causes aging. Consider helping this endeavor. Note that the crowdfunding page is in Portuguese at the top, and you will need to scroll all the way down for the English version of the project explanation:

We are Nina Torres Zanvettor and Nicolas Chernavsky, professional translators from Campinas (Brazil). Nicolas graduated as a journalist in USP (University of São Paulo) and has 13 years of experience as a translator. Nina graduated in Chemistry in Unicamp (University of Campinas), has a master degree in Inorganic Chemistry by Unicamp as well and works as a translator and a English teacher. The translation project of Ending Aging into Portuguese was created after Aubrey de Grey came to Brazil for the first time, in February of 2017. In that occasion, we met Aubrey after his talk at Campus Party, in São Paulo. We talked about the possibility of helping SENS using our professional experience in English-Portuguese translation. The scientific specialization of Nina together with the linguistic knowledge of Nicolas, mixed with a great dose of passion for the end of aging, could result in a translated version that would bring the ideas of the book to Portuguese speakers.

When we get sick and need medical assistance, or take a medicine or even go through a surgery, we realize the importance of healthcare. However, nowadays, medical science has still a lot of limitations. Diseases like Parkinson's, Alzheimer's, cancer and cardiovascular diseases are still practically inescapable when we reach a certain age. That's why the modern medicine is realizing that in order to defeat these diseases, we will have to face something that is difficult to face: aging. Only by defeating aging we could defeat these diseases, because they are the final phase of aging itself, which, in physical terms, is the accumulation of damage throughout our life at the cellular and molecular level.

Thus, this new area of medicine, focused on the aging issue, can give more decades of life to everyone. One of the world's most important scientists in this area, the British biogerontologist Aubrey de Grey, proposes a pathway so that in a few decades, probably still during the lifetime of most of the people still alive, we could build therapies to repair the damage caused by aging. The pathway proposed by Aubrey de Grey is called SENS (Strategies for Engineered Negligible Senescence). He identified seven basic types of cellular and molecular damage which result on aging: the mutations of our chromosomes, the glycation, the formation of extracellular and intracellular aggregates, the cellular senescence, the reduction of stem cell reserves and mitochondrial mutations. For each one of these forms of damage, Aubrey de Grey proposes a repair therapy.

Supporting this project, you are helping to spread knowledge in the area and to accelerate scientific research, contributing to the end of aging. We need the help of everybody in this journey towards the end of aging, and in this context, it's important to notice that the Portuguese language is the sixth most spoken language in the world, spoke by 273 million of people. Besides, in order for these technologies to reach everybody, this knowledge needs to reach everybody as well, including the Portuguese speaking world.


An Interview with Greg Fahy on Thymus Rejuvenation

Greg Fahy is currently wrapping up a trial of one of the simpler methods that might produce some degree of rejuvenation in the the thymus, turning back a little of the process of thymic involution, the withering of functional tissue in this organ. The thymus atrophies quite early in adult life, and further with later aging. As the thymus provides an environment for processes that are necessary in the creation of the immune cells called T cells, this decline limits the immune system. A faster pace of creation for T cells should help with some of the age-related deterioration of the immune system, which arises in part because too many of the existing cells become dysfunctional, and because the pace of replacement is too slow to keep up.

I think that this trial is unlikely to be enormously effective at addressing the problem, and will probably only produce modest effects, but the point of the exercise is to prove in humans that any degree of thymic restoration can produce a commensurate level of benefits. If that can be accomplished via this approach, then hopefully funds can be found to bring one of the more effective methods demonstrated in mice into human medicine: FOXN1 gene therapy, tissue engineering and transplant of replacement thymic tissue, some form of cell therapy to spur regeneration of new thymus tissue, and so forth.

So from around age 20 (or younger) the thymus begins to shrink and loses the ability to produce T cells, why does this happen?

Nobody knows why thymic atrophy, or involution, occurs, but it happens in all vertebrates, starting really at the age of puberty. Some have suggested that it happens to save energy, since the production of properly qualified T cells is very energy intensive and inefficient, and of course, at puberty, the body begins to devote more energy to reproduction, which might require a tradeoff against using energy for immune maintenance. This could be adaptive since, in nature, humans would not have lived long enough for immune system collapse to set in, even though today, the situation is different. Regardless of the evolutionary reason for it, the most immediate biochemical cause of involution seems to be mostly a drop in thymic FOXN1 expression, although some have pointed to a decline in intra-thymic IL-7 and the negative influence of circulating sex hormones, for example.

You recently ran a human clinical trial to regrow the thymus gland. Can you please tell us what is the main goal of the project and what is the progress?

The trial was conducted under an FDA-approved IND and with review from multiple scientific and ethics committees. It consisted of a 12-month treatment course for 9 men divided into two cohorts, with the first cohort starting in October of 2015 and the second ending in April of this year. Our goal was to gather preliminary evidence indicating that it is possible to safely regenerate the normal aging human thymus and restore its functions, essentially reversing the process of age-related immunological deterioration. We chose to work with healthy men in part because this was a small trial, which required a reasonably uniform population, and in part because more information was available for men than for women. We chose an age range of 50 to 65 years because this range extends from several years before to a few years after the threshold age at which the immune system tends to collapse. Success would therefore suggest the possibility of preventing or even reversing the early stages of immune collapse. In future trials, we intend to enroll both women and older men.

The outcome measures included MRI evaluation of thymic density before and after treatment, simple and sophisticated assessment of T cell population distributions, measurements of many serum factors related to immune system function and general health, lymphocyte telomere length distributions and telomerase activity, and biological age based on the Horvath epigenetic clock. Regarding our results, first of all, when you're working with human beings, safety has to be the top priority, so I'm glad to be able to say that we met or exceeded all of our safety targets. Regarding thymic imaging results, preliminary analyses indicate that there was a consistent and substantial increase in thymic density, which indicates replacement of thymic fat with more water-rich material, and in previous studies on human immunodeficiency patients, this coincided with improved thymic function. Superficial tests of immune system aging showed improvements in 8 out of 9 men, and we were able to identify a possible correctable reason for the failure of the 9th volunteer. Men of all ages were able to respond positively and to avoid side effects. However, the most definitive endpoints of our study are still being analyzed at four different locations around the world, so we won't really know the final results of our study for probably another month or two.

Are we going to see a publication anytime soon?

I'm not sure about soon, but certainly, as soon as we can. This will be a complicated paper with lots of authors and lots of data to present, but also with top-tier academic co-authors who can help us go through the scientific review process quickly. In any case, we certainly want to make sure that any novel results are shared with the broader medical and scientific communities.


Can Aging be Slowed by Shutting Off the Inflammatory Signaling of Senescent Cells?

Today I'll point out an interesting paper in which researchers sabotage the ability of senescent cells to generate inflammation. Senescent cells are one of the root causes of aging. They are created constantly in all tissues, a normal part of the operation of cellular metabolism, but near all are destroyed shortly thereafter. Those that linger cause ever greater disruption and failure in tissues and organs because they secrete a variety of signals known as the senescence-associated secretory phenotype (SASP), useful in the short term and when localized, but outright destructive over the long term or in great volume. One of the characteristic outcomes of the presence of lingering senescent cells is a significant increase in chronic inflammation, and this in turn accelerates the progression of all of the common age-related conditions.

With regards to what to do about senescent cells, the research community seems fairly evenly split between groups working on ways to destroy them and groups working on ways to modulate their activities. I think the former approach will be far more beneficial in the near term: it bypasses the need to understand in detail all of the highly varied senescent cell signals and their effects, a task that will likely still be ongoing a decade from now. Further, modulating the signals of senescent cells without removing them will require continual medication, rather than the envisaged infrequent, once-every-few-years treatments that clear out senescent cells. I see this as one of many areas in which the rational incentives in academic research (find out more, map more of the system, better understand the whole picture) seem to lead inexorably towards the production of objectively worse solutions in medicine.

That to one side, and as today's research illustrates, researchers appear to be making some progress in linking existing knowledge on inflammatory signaling to the the quickly growing knowledge of the biochemistry of senescent cells in aging. I mentioned another paper on this same topic and mechanism a couple of months ago. Here, the authors have found a way to interfere in one of the primary pathways by which senescent cells communicate with the immune system, and demonstrated in mice that this can blunt some of the consequences of high levels of senescence that are artificially induced through techniques such as irradiation. Unfortunately this also prevents the beneficial short-term benefits arising from senescence-associated inflammation, such as in immune surveillance of cancer. It remains to be seen as to how much of an effect this sort of approach will have on the consequences of cellular senescence in normally aging mice. Not to mention humans: at this point we really have no idea what the impact of clearing senescent cells will turn out to be in our species, never mind any of the possible approaches to selectively reduce the impact of their signaling in very narrow ways.

Cell Stress Response Sheds Light on Treating Inflammation-related Cancer, Aging

Human cells have complicated ways to protect themselves from becoming cancerous. One way is to force "premature aging" via senescence, a process that induces cells to stop growing. Although senescence suppresses cancer, which is the good side of this physiological balance, there is also a dark side. Senescence is associated with normal aging, and senescent cells accumulate in aged tissues. This accumulation impairs healthy tissue by triggering hyper-inflammation. This overdrive eventually contributes to age-related diseases including cancer, heart disease, and neurodegeneration. The overall idea for future therapy is to make a small molecule that could stop the dark side of senescence to treat age-related diseases, especially those related to chronic inflammation.

"Chromatin - structures in the cell nucleus in which genes reside - is traditionally viewed as a cell component that stays put in the nucleus to regulate gene expression. We discovered misplaced chromatin fragments outside the nucleus that pinch off from the nuclei of senescent cells." This wayward chromatin activates a DNA-sensing pathway called cGAS-STING, a mechanism based outside the nucleus best known for restraining microbial infection, such as by bacteria or viruses. In the case of senescence and aging, the body's own chromatin leaking outside of the nucleus is read by cells as a "danger signal" akin to a microbial infection. The misplaced fragments and the cell's reaction to them eventually lead to inflammation. "While short-term inflammation can help stop cancer from starting, the problem is that long-term, chronic inflammation can lead to tissue destruction, aging, and even, paradoxically, can help cancer to grow and spread."

Mice without an active alarm pathway that have been exposed to a cancer-inducing stress do not call the immune-system for help. This causes problems because damaged cells give rise to tumors in the impaired mice. However, when normal mice are exposed to stressors that induce aging, the build-up of senescent cells stimulates a continual call for immune cells, leading to chronic inflammation, which ultimately causes tissue damage and premature aging. Months after receiving irradiation stress, normal mice with an active alarm system showed massive graying of their fur, a sign of aging in mammals, just like humans show grey hair in old age. By sharp contrast, mice without the alarm system still had their black fur after irradiation. The researchers believe that finding molecules to target the always-on inflammatory pathway may hold promise in treating chronic inflammation associated with numerous diseases, especially those of aging, such as arthritis, arteriosclerosis, neurodegeneration, obesity, and possibly even hair graying and loss.

Cytoplasmic chromatin triggers inflammation in senescence and cancer

Chromatin is traditionally viewed as a nuclear entity that regulates gene expression and silencing. However, we recently discovered the presence of cytoplasmic chromatin fragments that pinch off from intact nuclei of primary cells during senescence, a form of terminal cell-cycle arrest associated with pro-inflammatory responses. The functional significance of chromatin in the cytoplasm is unclear.

Here we show that cytoplasmic chromatin activates the innate immunity cytosolic DNA-sensing cGAS-STING (cyclic GMP-AMP synthase linked to stimulator of interferon genes) pathway, leading both to short-term inflammation to restrain activated oncogenes and to chronic inflammation that associates with tissue destruction and cancer. The cytoplasmic chromatin-cGAS-STING pathway promotes the senescence-associated secretory phenotype in primary human cells and in mice.

Mice deficient in STING show impaired immuno-surveillance of oncogenic RAS and reduced tissue inflammation upon ionizing radiation. Furthermore, this pathway is activated in cancer cells, and correlates with pro-inflammatory gene expression in human cancers. Overall, our findings indicate that genomic DNA serves as a reservoir to initiate a pro-inflammatory pathway in the cytoplasm in senescence and cancer. Targeting the cytoplasmic chromatin-mediated pathway may hold promise in treating inflammation-related disorders.

A Slowly Spreading Realization that Radical Change in Human Longevity Lies Ahead

The author of this piece appears quite disgruntled about the prospect of living longer in good health, given an expectation of severe upheaval in government programs of entitlements relating to medical services, pensions, and other wealth transfers that are currently (poorly) structured around the reality of a population expensively and painfully aging to death. Nonetheless, it is an example of the point that a realization is spreading regarding the plausibility of sizable near future changes in human longevity: as that occurs there will be - and must be - large changes in the flows of money associated with aging, from life insurance and annuities to the structure of public funds.

Many of these changes will be disruptive, and those who relied upon government planners and politicians to help them will be let down, as is always the case. A distant and largely unaccountable bureaucrat never has your best interests in mind. There are plenty of examples to survey from just the past decade of large-scale financial issues around the world. So prepare accordingly when considering the future - but why be disgruntled? Being alive and in good health, as opposed to the alternative, is a prize worthy of considerable effort. And if you are alive and in good health for decades longer than expected, then why think of retirement? Why not continue to participate in an active life and a career?

Is the rise in life expectancy in the West coming to an end? This year the Office for National Statistics (ONS) announced something depressing: a slight fall in life expectancy for pensioners - six months for women and four for men. Overall, life expectancy is still rising but at a much slower rate than everyone thought it would. There is no shortage of experts out there prepared to explain why life expectancy has stalled. Maybe it's a result of the financial crisis, a failure of elderly care linked to austerity? Maybe it's obesity, something that could even make today's young the first generation to live shorter lives than their parents? Or maybe it is just that we are already close to the outer limits of possibility when it comes to life expectancy?

Yet look a little closer and talk to longevity experts and healthcare investors and a different picture emerges. The slowdown in life expectancy actually comes at a time when the science of ageing is getting very exciting. Much of the rise in life expectancy of the past 50 years has been down to environmental effects: the near eradication of real poverty in the West; the rise of universal medical treatment; antibiotics; better air quality; improved working conditions. All these things should keep adding a little more to the numbers. They are also just the beginning. Next will come an enhanced understanding of what actually causes ageing and how it can be stalled, alongside the start of mass molecular fiddling.

The new book Juvenesence: Investing in the Age of Longevity forecasts that within the next 20 years average life expectancy in the developed world will rise to between 110 and 120. This makes the authors happy. Their book is full of soothing thoughts. That's going to sound lovely to most people. But you can bet there is a large group who find it totally terrifying: policymakers. Ageing populations are very expensive. Our systems aren't yet in any way equipped to cope with the odd half a million 90-year-olds the UK has already, let alone millions of 100-year olds. Our health and welfare systems were designed for a different era, and the unfunded liabilities of public and private pension funds are the kind of thing that never get addressed.

This should make individuals worry, too. Very few people have planned properly for their own retirements - and even if they have, extended longevity will mean that the assumptions on which they have based their calculations are entirely wrong. On top of this, almost no one will have planned for the fact that this will make governments that don't seriously reform - my guess is that's all of them - increasingly broke. Nor will they have planned for the obvious next step: that cash-strapped governments look to other people's capital for help. If we do enter a new age of the long-lived, it will probably be less an age of the happy rentier than the very heavily taxed rentier. If you don't want to spend your 11th decade wishing that longevity science had never become a thing, think of what you once thought you should save for your retirement and triple it. Golden years? Working years.


Delivery of Extracellular Vesicles for Regenerative Therapy in Bone Tissue

A sizable portion of signaling between cells is carried by vesicles, tiny packages of secreted molecules wrapped in a membrane. Investigations of the effects of early stem cell therapies have revealed that in many cases whatever benefits are realized must be produced by signals that induce behavioral changes in native cells, since the transplanted cells die quite quickly. Now researchers are beginning to look at harvesting or manufacturing suitable vesicles as a way to recreate some of the beneficial effects of cell transplantation, a path that bypasses the need to create patient-matched cells or otherwise deal with immune rejection issues. This part of the field is at a very early stage, but nonetheless examples such as the study here are emerging:

A recent paper describes a new approach to bone regeneration; stimulating cells to produce vesicles which can then be delivered to facilitate tissue regeneration. The researchers believe that the findings mark the first step in a new direction for tissue regeneration with the potential to help repair bone, teeth and cartilage. Current approaches have significant limitations; autologous grafts cannot meet demand and cause patient morbidity, allogeneic bone lacks bioactive factors, and growth factor-based approaches (e.g. BMP-2) may have serious side-effects and high costs. Consequently, there is a considerable need to devise new methods for the generation of large volumes of bone without associated patient morbidity.

In recent years, attention has been focused on cell-based approaches. However, translation is frequently prevented by insurmountable regulatory, ethical and economic issues. This novel solution delivers all the advantages of cell-based therapies but without using viable cells, by harnessing the regenerative capacity of nano-sized particles called extracellular vesicles that are naturally generated during bone formation. Excitingly, the team have shown in-vitro that if extracellular vesicles are applied in combination with a simple phosphate the therapy outperforms the current gold standard, BMP-2. "It is early days, but the potential is there for this to transform the way we approach tissue repair. We're now looking to produce these therapeutically valuable particles at scale and also examine their capacity to regenerate other tissues."


Considering Autophagy in the Context of Stem Cell Aging

In the paper I'll point out today, the topic is autophagy and stem cell aging. You can't wander far in the libraries of research relating to aging without bumping into a discussion of autophagy. This is a collection of quality control processes for cellular structures and proteins, working to destroy those that have become damaged or dysfunctional in some way. Damage of any number of different types occurs constantly inside cells, and so does repair: any sort of of unwanted modification of a protein alters its behavior, making it unsuitable for its intended task. Unfortunately, proteins are fragile, and cells are full of reactive molecules and damaging reactions. The longer that damaged components remain in circulation, the more secondary harm they can produce, both within the cell, and beyond in the surrounding tissue. Given that, it is understandable that greater levels of autophagy should produce better function and longer-lasting biological structures at all levels. Indeed, more autophagy slows the aging process to some degree, as demonstrated in numerous studies of short-lived laboratory species. Aging is caused by an accumulation of certain forms of damage that arise from the normal operation of cellular metabolism, and thus processes relating to general damage control tend to have some impact.

Still, there are limits. Greatly increased autophagy only somewhat slows aging. The forms of damage that are important in the long term are not greatly hampered by the constant efforts to repair the far more numerous other forms of damage. It makes sense to consider that aging could really only result from forms of damage that autophagy isn't all that effective at preventing. Consider mitochondrial damage for example, well-studied in the context of aging: the processes of mitophagy break down dysfunctional mitochondria, but the specific mitochondrial damage that causes aging is resistant to mitophagy. The quality control mechanisms cannot efficiently recognize that specific damage and its consequent mitochondrial dysfunction as a signal to remove the problem structures.

Autophagy declines with age, just like every other cellular system, as the components required for recycling of structures become dysfunctional over time. To pick one example, the lysosomes in long-lived cells, responsible for breaking down proteins and other structures in the cell, become bloated by metabolic waste that is hard for them to deal with. This prevents them from carrying out their recycling tasks, and as a result the cell eventually breaks down in a garbage catastrophe. Aging itself might be thought of as a process that commences with a failure of repair: once the maintenance systems decline, everything else follows rapidly. As is the case for autophagy, the tissue maintenance activities of stem cells decline with age, and there are links between the failure of a cellular process and the failure of an entire cell population to carry out its duties.

Autophagy in stem cell aging

Proteostasis is necessary for most cellular functions, such as genetic replication, catalysis of metabolic reactions, and the immune response. Impairments in proteostasis can lead to toxic aggregations and accumulation of unwanted proteins resulting in cellular dysfunction. The maintenance of tissue homeostasis and the regenerative capacity after an injury depends on tissue-specific stem cells. The elucidation of the hallmarks of aging identified the impairment of protein homeostasis and stem cell exhaustion as major processes involved in the decline of the regenerative potential capacity linked to the accumulation of age-associated damage.

Autophagy is a highly conserved catabolic process, essential for this protein quality control, where intracellular components are delivered to lysosomes for self-degradation. There are three different types of autophagy depending on the signals that induce the pathway, and the mechanism by which the cargo reaches the lysosome: macro-autophagy (MA), micro-autophagy, and chaperone-mediated autophagy (CMA). In particular, MA is involved in recycling long-lived proteins and cytoplasmic organelles. This process implies the incorporation of proteins, organelles, and cytoplasm in a structure called the autophagosome, which once formed fuses with the lysosome to form autolysosomes and then releasing its content in the lysosomal lumen where it is degraded via acid hydrolases. Autophagy basal levels are very low under normal conditions, and they are activated in response to stress and extracellular cues.

Aging results from the accumulation of cellular damage promoted by chronic stresses of small magnitude. Therefore, being a sensor of stress, autophagy has been linked to aging. Several studies have described a decline in autophagy activity as well as expression of autophagy genes such as Atg1, Atg5, Atg6, Atg7, Atg8, and Atg12 in response to aging in several animal models and human tissues. The majority of these works have focused on MA, the most studied form of autophagic process, but there have also been studies showing a decline in CMA, particularly in the liver and the central nervous system, which have been linked to decreased function in these organs. Longevity studies with gain and loss of autophagy genes in animal models such as yeast, C. elegans, Drosophila and mice, support a direct role for autophagy in longevity, aging and development of age-associated pathologies. This has encouraged the scientific community to identify the precise role and molecular mechanisms of autophagy in aging, as targeting autophagy could be a novel therapy against aging and age-related diseases.

How autophagy decreases with age remains unclear and under intense investigation. Recent works carried on aged muscle stem cells (MSC) and hematopoietic stem cells (HSC) have revealed the impairment of MA in stem cell activity with aging. Moreover, these studies have confirmed that correct functioning of MA is necessary to maintain the appropriate blood system and muscle development and to allow adult stem cell to survive under metabolic stress. These studies suggest that MSC and HSC lose their regenerative abilities when they reach an advanced age and that autophagy is deficient in the old stem cell population. In a recent work, it was found that approximately 30% of aged HSCs exhibited high autophagy levels, maintaining a low metabolic state and strong long-term regeneration potential similar to young HSCs. However, the remaining population of aged HSCs showed loss of autophagy, which causes activated metabolic state, accelerated myeloid differentiation, and impaired HSCs self-renewal activity and regenerative potential.

These studies confirm that autophagy maintains stemness in MSC and HSCs; however, the maintenance of this feature seems to be different in each niche. Whether these results can be translated to other stem cell niches will be determined in the future. In addition, it will also be important to elucidate whether CMA or micro-autophagy play any role in stem cell aging. In summary, there is a requirement of correct autophagy activity for stem cell function, and the pharmacological restoration of autophagy is postulated as a novel strategy to boost stem cell activity for regenerative medicine and aging.

Genetic Interaction with Temperature in Nematode Longevity

Environmental temperature and longevity tend to be related in species that do not maintain their body temperature. You might look at research into the sizable differences between life spans of various mussel species and how that relates to the temperature of the waters in which they are found, for example. It is an interesting question as to how relevant this research is to mammals, which do regulate their body temperature. While there appears to be a relationship between regulated body temperature and longevity in mammalian species, it is far from clear that this has much in common with the environmental temperature and longevity relationships observed in species such as the nematode worms investigated here. In any case, this, like calorie restriction, is not the road to rejuvenation therapies that will radically alter the present course of aging. Rather, it is the path to a better understanding of how the natural state of aging tends to vary between individuals and species. This is interesting, but not transformative.

As in other poikilotherms, longevity in C. elegans varies inversely with temperature; worms are longer-lived at lower temperatures. While this observation may seem intuitive based on thermodynamics, the molecular and genetic basis for this phenomenon is not well understood. In C. elegans, animals that develop and age at 15 °C ('low temperature') are long-lived compared to wild-type animals grown at 20 °C (room temperature), whereas wild-type worms that develop and age at 25 °C ('high temperature') are short-lived compared to wild-type worms grown at 15 °C or 20 °C. This 'temperature law' has been described as widely accepted, but not tested beyond limited number of strains.

While the 'temperature law' is observed among wild-type organisms, the interplay between genetics and temperature is not well understood. Multiple recent reports suggest that the effects of temperature on longevity are genetically controlled and that both heat and cold modify transcriptional pathways that effect lifespan. To better understand the interplay between temperature and longevity, we measured the lifespans of worms with genetic manipulations known to affect longevity at 15 °C, 20 °C, or 25 °C. We found six examples of how longevity can be impacted across temperatures, representing conditions that: robustly increase lifespan at all temperatures (daf-2 RNAi); robustly decrease lifespan at all temperatures (rhy-1(ok1402)); decrease lifespan at high but not low temperature (daf-16(mu86)); increase lifespan at high temperature but decrease lifespan at low temperature (rsks-1(ok1255)); increase lifespan at low temperature but not high temperature (cep-1(gk138)); and do not alter lifespan at any temperature (cah-4 RNAi).

Having established that relative longevity can vary across temperatures, we next asked whether this variability is common among conditions known to modify longevity. We tested nearly fifty genotypes and interventions previously reported to affect lifespan and found that relative longevity was consistently inconsistent across temperatures. However, there are consistent trends within longevity pathways, where strains/conditions known to have opposing effects are also affected by temperature oppositely. In summary, we find significant interaction between longevity interventions and environmental temperature in two-thirds of the cases examined, indicating that a temperature-independent effect on longevity is more the exception than the rule. This variation confirms that genetics play a substantive role in temperature-dependent longevity that cannot be explained solely by the rules of thermodynamics and chemical kinetics. The observed variation in relative longevity with temperature is consistent with the hypothesis that distinct mechanisms determine nematode longevity at different temperatures.

It has been suggested that protein quality control and the heat stress response are of primary importance for determining nematode longevity at 25 °C. Our data support this model; we find interventions that limit heat stress response (e.g., daf-16(mu86)) are detrimental at high, but not low, temperature, while interventions that improve protein homeostasis, such as dietary restriction or reduced expression of translation machinery (e.g., rsks-1(ok1255), rpl-6 RNAi), show lifespan extension at high temperature. The relevant mechanisms affecting longevity at low temperature are less clear, particularly because relatively few aging studies are conducted at 15 °C compared to 20 °C or 25 °C. Our results demonstrate that the impact of temperature on relative lifespan is of greater importance than generally appreciated by the C. elegans aging field. The vast majority of published studies report the impact of different interventions on lifespan at a single temperature, usually either 20 °C or 25 °C. We suggest that studies reporting effects on lifespan should typically be performed at more than one temperature to understand the robustness of the effect and the interaction with temperature.


A Gene Therapy Restores Some Degree of Vision in Mice with Retinal Degeneration

The paper I'll point out here is an excellent example of the glacial pace of many lines of research. Years can pass between studies that look very similar, and one wonders what has been taking place in between, if anything. It has been nearly ten years since I first pointed out a study demonstrating partial restoration of visual function - at least sensing of light and darkness in the visual field - in mice with retinal degeneration. A gene therapy was used to produce expression of the protein melanopsin in retinal cells where it is usually absent. This in turn allowed these cells to participate in the light-sensing activity of the retina, where usually they would not. In effect it was providing a sort of rudimentary backup to the photoreceptor cells that are lost in degenerative conditions affecting the retina.

This week, a new paper has arrived to document a recent study of melanopsin gene therapy in which the only real differences from the study conducted a decade ago are that the mice are followed for longer after the procedure, a year, a more modern method of gene therapy is employed, and the melanopsin is the human version rather than the mouse version. At this pace, the approach will be made obsolete by progress elsewhere in the field before any sort of clinical translation ever starts.

Even in end-stage retinal degeneration such as retinitis pigmentosa (RP), the remaining retinal layers and central visual projections remain structurally intact. Stimulation of these remaining cells is potentially sufficient to mimic visual responses and restore vision, and by this means the subretinal electronic implant has shown proof of principle for restoration of vision in patients after severe photoreceptor loss. An alternative gene therapy strategy involves the expression of transgenes encoding photosensitive proteins in remaining retinal cells, making them directly light sensitive in the absence of rods and cones.

A candidate protein for this purpose is melanopsin, the photopigment naturally present in a subset of ganglion cells that are intrinsically photosensitive - intrinsically photosensitive retinal ganglion cells (ipRGCs). Melanopsin is particularly suited to this purpose since it is native to the human eye and therefore is less likely to be immunogenic. Melanopsin shows greater sensitivity to light than alternative microbial optogenetic tools, such as channelrhodopsin-2 or halorhodopsin.

Previous work used intravitreal delivery of an adeno-associated viral (AAV) vector to express mouse melanopsin in ganglion cells with restoration of visual responses. We investigated whether human melanopsin could be effectively delivered via an alternative subretinal approach, using a ubiquitous (CBA) promoter to drive expression in all remaining outer retinal cells for several reasons. Subretinal vector delivery is well established in human clinical trials but has not been assessed in combination with a CBA promoter as an optogenetic approach for vision restoration. Transduction of cells in the upstream retina maximizes the potential of retaining complex processing of the visual signal. Furthermore, increased availability of chromophore in the outer retina may be required for effective photon capture in the absence of specialized outer segment discs. Other studies have used AAV vectors containing an enhancer to target a melanopsin-mGluR6 chimera or rhodopsin via intravitreal injection. However, there is variation in anatomy between primates and mouse models, and this may render the intravitreal approach less effective in humans. The increased risks of an inflammatory response following intravitreal AAV injection may also limit the translational potential of this route of delivery.

We therefore assessed transduction following subretinal delivery of melanopsin and whether this could support long-term restoration of light sensitivity and visual function in a mouse model of end-stage RP. Ectopically expressed melanopsin mediated depolarization of outer retinal cells and ultimately ganglion cell action potential firing, resulting in long-term restoration of the pupil light reflex and behavioral light avoidance up to at least 13 mo following injection. Finally, subretinal melanopsin expression led to light-induced changes in visual cortex blood flow and provided long-term improvements in a visually guided behavioral task that requires image-forming vision. In combination, these results suggest that this approach may be clinically useful in vision restoration in patients with end-stage RP.


MouseAge Crowdfunding Project Gains a Matching Fund: Donations are Doubled

Longevity Month is upon us once more, and this year it finds that the MouseAge crowfunding project has been running for a few weeks at The MouseAge developers are building a visual aging biomarker system, akin to past work on the assessment of human age from facial photographs, but carried out for mice instead of people. Such a system could in principle greatly reduce the cost of many kinds of exploratory study in mice, enabling rapid first passes at evaluating the effects of potential rejuvenation therapies. Currently this sort of work is an expensive and lengthy process of wait and see: a range of low-cost methods of immediate assessment of biological age are definitely needed to speed up progress towards therapies capable of treating the causes of aging, and the visual assessment approach is an intriguing one. With the start of Longevity Month, the volunteers have announced a matching fund for donations to the project - donate this month, and your contribution is doubled.

What is Longevity Month? Advocates for longevity science, those who call for faster progress and more investment into the development of working rejuvenation therapies, have settled upon October as a month for fundraising and outreach activities. This started a few years ago with the European volunteers of the International Longevity Alliance and Heales, as the United Nations designates October 1st as the International Day of Older Persons, and the European community has tended to hold events at this time of year, such as last year's Eurosymposium on Healthy Aging. Advocates mark October 1st as Longevity Day and the month of October as Longevity Month. Small beginnings and simple ideas like this can help to produce meaningful change as they grow and spread - consider the originally humble origins of many of the now widely known and celebrated theme days, commercial and otherwise. Someone thought that he or she would give it a try, and it worked. It never hurts to try, and it is certainly the case that advocacy for any cause is a matter of trying all of the plausible options until you find the one that works, the one that everyone will later tell you was strikingly obvious, and ask why you didn't just try that first of all? Successful strategies are always obvious in the hindsight of others, but sadly only there.

MouseAge Longevity Month Updates - Extension, Matching Funds and More!

To coincide with our initiatives for Longevity Month, we are happy to announce some exciting updates for the MouseAge campaign to create a visual biomarker for mouse aging and speed the pace of longevity-focused mouse trials. The A.I. engineers on the team , with the support of Youth Laboratories, have decided to volunteer their assistance, pledging to donate their time in developing the machine learning algorithm and software engineering components of this project. This will effectively allow all goals on the crowdfunding campaign to be reduced by $15,000, and the initial goal will now stand at $15,000.

Together with a coalition of generous supporters LEAF has built up a pool of matching funds to support the campaign. This means that all donations will be doubled up until the new initial goal of $15,000 is reached. $1,000 in matching funds will be released for every $1,000 donated, so together we can move very quickly to support this important project!

Longevity Month 2017 - Tell Us Your Story!

Over the past few years there has been a tradition of longevity researchers and activists around the world organizing events on or around October 1 - the UN International Day of Older Persons, or Longevity Day. This year we want to continue this tradition by doing something special, making a video to showcase you, our community, as it is only with your outstanding help that we have been able to accomplish so much in such a short period of time. So now it is your turn to tell us your story, and let the world know why you care about research to end the diseases of aging. We will be accepting videos all through the month of October, Longevity Month, and we are also extending the MouseAge campaign to match this timeline. With these videos we will create a compilation to be unveiled on Giving Tuesday , November 28, 2017.

Macrophages Promote Muscle Regeneration via Secretion of ADAMTS1

The immune cells known as macrophages play an important role in regenerative processes, as demonstrated by the fact that if they removed from the picture, the pace and quality of tissue healing deteriorates considerably. A number of studies suggest that macrophages have two characteristic behavior patterns, the first an inflammatory behavior associated with destruction of invading pathogens, and the second focused on coordination of regeneration. Both behaviors are in evidence at the site of a wound, and healing can be improved by adjusting their proportions away from inflammation and towards regeneration. Further, studies are beginning to show that differences in macrophage behavior appear to be part of the reason why species such as salamanders and zebrafish have such proficient regenerative capacities. This is evidently a promising area of research, and here scientists report on the identification of one of the specific signals involved in the macrophage influence on regeneration:

The progressive activation and differentiation of satellite cells is critical for proper skeletal muscle growth and muscle regeneration after injury. This cascade is initiated when satellite cells are activated to break quiescence, progress through differentiation, and fuse to nascent or injured muscle fibers. Therefore, elucidating the signals and pathways that regulate this cascade is central to understanding muscle physiology and could provide a foundation for developing novel therapies for the treatment of muscle disorders and regenerative medicine.

Activation of satellite cells occurs in response to a variety of chemical, physical and physiological cues to mediate muscle tissue homeostasis and regeneration. The specialized niche of satellite cells, which are located between the basal lamina and the myofiber, is a critical element in the regulation of satellite cell quiescence and activation. For example, activated Notch signaling, which is directly regulated by proximal extracellular signals, is a well-studied example of a potent pathway that plays an important role in maintaining satellite cell quiescence. In addition, ADAM10, an enzyme known to promote Notch signaling, was found to have a role in the maintenance of the quiescent state. Yet, in spite of the apparent canonical role of Notch signaling in the regulation of satellite cell activation, the extracellular triggers that inhibit Notch signaling and promote satellite cells to break quiescence and differentiate are largely unknown.

Here we describe our discovery that macrophages, which are enriched at the site of muscle injuries, secrete a protein called ADAMTS1 (A Disintegrin-Like And Metalloproteinase With Thrombospondin Type 1 Motif). ADAMTS1 contains two disintegrin loops and three C-terminal thrombospondin type-1 motifs. We established that ADAMTS1 functions as an extracellular signal to satellite cells that promotes activation. We also found that constitutive overexpression of Adamts1 in macrophages accelerates satellite cell activation and muscle regeneration in young mice. Our data indicate that the mechanism of this ADAMTS1 activity is by targeting NOTCH1 protein on the satellite cells. These findings significantly enrich our understanding of the extracellular signals that regulate satellite cell activation and identify a pathway that could potentially be targeted with therapeutics to enhance muscle regeneration.


TRF1 Gene Therapy Improves Health Span in Mice

One of the research groups interested in telomerase gene therapy and its ability to lengthen mouse life span also works on a number of related items, such as the potential to shut down cancers by dramatically accelerating the erosion of telomeres in cancerous tissue, telomeres being the caps of repeated DNA sequences at the end of chromosomes. As is true elsewhere in biochemistry, here it is the case that a mechanism influential on aging is also important in cancer. Other approaches to cancer that involve telomeres include sabotaging the ability of telomerase to extend telomeres. This sort of thing can form the basis for a potential therapy that could in principle put a halt to all types of cancer. All cancers, without exception, depend on the abuse of either telomerase or alternative lengthening of telomeres (ALT) in order to keep telomeres long and thus keep replicating rampantly. Each cell division shortens telomeres a little, and when telomeres become too short, a cell self-destructs or becomes senescent, in either case ceasing to replicate. Thus without telomere lengthening, a cancer must inevitably wither away.

The method used to accelerate telomere length loss is a blockade of TRF1, a component of shelterin, which appears necessary to the operation of various processes that help to maintain telomere integrity. Given other work on telomeres and telomerase, it makes sense to ask whether turning this around to enhance levels of TRF1 and its activity will slow aging in mice, as is the case for the use of gene therapy to increase telomerase levels. Researchers here show that the enhanced TRF1 approach does extend the span of healthy life in mice, but doesn't have much of an effect on overall life span. I think that most of the commentary on telomerase gene therapies made in recent years probably also applies to this work, particularly with respect to whether or not the effect is mediated through increased stem cell activity, potential applications, expected degree of safety in humans, the sizable differences between mouse and human telomere dynamics, and so on.

Telomere shortening has been identified as one of the primary hallmarks of aging. Mammalian telomeres are structures at the end of linear chromosomes that consist of repeated DNA bound by an array of associated proteins known as shelterin, which prevent chromosome ends from being recognized as double-strand DNA breaks and from chromosome end-to-end fusions. Telomerase is a reverse transcriptase (TERT) that elongates telomeres de novo by adding telomeric repeats on chromosome ends using as template an RNA component (TERC), thus preventing telomere erosion. However, mammalian cells stop expressing telomerase in the majority of tissues after birth, leading to progressive telomere erosion throughout the lifespan of the organism. Telomere shortening has been demonstrated to be sufficient to trigger age-related pathologies and shorten lifespan in mice.

Telomerase reactivation has been envisioned as an strategy to maintain telomeres and therefore to increase the proliferative potential of tissues, both in the telomere syndromes and in age-related conditions. In addition to telomerase, the shelterin complex is also critical for the protection of telomeres. Shelterin consists of six proteins, of which TRF1 is one of the key components. In particular, deletion of TRF1 in mouse embryonic fibroblasts (MEFs) results in induction of senescence, as well as in chromosome fusions and multitelomeric signals (aberrant number of telomeric signals per chromosome end). Importantly, these effects of TRF1 abrogation are independent of telomere length, as TRF1 deletion uncaps telomeres independently of telomerase and cell division. In addition, conditional TRF1 abrogation in various mouse tissues has demonstrated the importance of TRF1 for tissue regeneration and tissue homeostasis. Indeed, high TRF1 levels mark stem cell compartments as well as pluripotent stem cells and are essential to induce and maintain pluripotency.

Given the importance of TRF1 for organismal viability and tissue homeostasis, here we set to address whether TRF1 levels vary with aging in vivo both in mouse and human tissues, as well as to study the potential therapeutic effects of TRF1 increased expression in delaying aging-associated pathologies in vivo. A previous work of our group showed that constitutive TRF1 overexpression acted as a negative regulator of telomere length, mediating telomere cleavage by XPF nuclease. To circumvent this undesired effect of TRF1 overexpression, here we induced moderate and transient TRF1 overexpression in adult (1 year of age) and old (2 years of age) mice using nonintegrative adeno-associated gene therapy vectors (AAV) that can transduce many different tissues but their expression is diluted as cells proliferate.

The results shown here demonstrate that TRF1 levels decrease with age both in mice and in humans. Furthermore, we demonstrate that transient TRF1 expression through the use of AAV9-TRF1 gene therapy in wild-type mice is able to improve mouse physiological health span as indicated by improvements in different markers of aging. AAV9-TRF1 gene therapy significantly prevented age-related decline in neuromuscular function, glucose tolerance, cognitive function, maintenance of subcutaneous fat, and chronic anemia. Interestingly, although AAV9-TRF1 treatment did not significantly affect median telomere length, we found a lower abundance of short telomeres and of telomere-associated DNA damage in some tissues.