Fight Aging! Newsletter, March 19th 2018

As people grow older, their leg muscles become progressively smaller and weaker, leading to frailty and disability. While this process inevitably affects everyone living long enough, until now the process has not been understood. New research suggests that muscle wasting follows on from changes in the nervous system. By the age of 75, individuals typically have around 30-50% fewer nerves controlling their legs. This leaves parts of their muscles disconnected from the nervous system, making them functionally useless and so they waste away.

However, healthy muscles have a form of protection, in that surviving nerves can send out new branches to rescue some, but not all, of the detached muscle fibres. This protective mechanism is most successful in older adults with large, healthy muscles. When the internal protective mechanism is not successful and nerves are unable to send out new branches, it can result in extensive muscle loss. This can result in a condition called sarcopenia, which affects an estimated 10-20% of people aged over 65 years.

The researchers are currently looking at whether regular exercise in middle- and older-age slows the process of muscles becoming disconnected from the nervous system, or improves the success of nerve branching to rescue detached muscle fibres. The goal is to identify the best type of exercise - strength training or endurance - and to understand the physiology of why the nerve-muscle changes occur as we get older.

Sarcopenia results from the progressive loss of skeletal muscle mass and reduced function in older age. It is likely to be associated with the well-documented reduction of motor unit numbers innervating limb muscles and the increase in size of surviving motor units via reinnervation of denervated fibres. However no evidence currently exists to confirm the extent of motor unit remodelling in sarcopenic individuals. The aim of the present study was to compare motor unit size and number between young (n = 48), non-sarcopenic old (n = 13), pre-sarcopenic (n = 53) and sarcopenic (n = 29) men.

Motor unit potentials (MUPs) were isolated from intramuscular and surface electromyographic recordings. The motor unit numbers were reduced in all groups of old compared with young. Motor unit potentials were enlarged in non-sarcopenic and pre-sarcopenic men compared with young, but not in the vastus lateralis of sarcopenic old. The results suggest that extensive motor unit remodelling occurs relatively early during ageing, exceeds the loss of muscle mass, and precedes sarcopenia. Reinnervation of denervated muscle fibres likely expands the motor unit size in non-sarcopenic and pre-sarcopenic old, but not in the sarcopenic old. These findings suggest that a failure to expand the motor unit size distinguishes sarcopenic from pre-sarcopenic muscles.

Substantial regulatory reform is needed to create a pathway for investors and pharma to put the necessary time and money into researching and developing rejuvenation biotechnologies such that licensable therapies can come out the other end. The most important regulatory reform would entail acceptance of novel biomarkers of the removal, repair, replacement, or rendering harmless of specific forms of cellular and molecular aging damage as sufficient basis to grant rejuvenation biotechnologies preliminary licensure. This would then be followed up by further monitoring of patients to ensure that the therapy actually does bend the curve on diseases of aging over the longer term. This standard would mark a break with regulators' usual insistence (which has been getting more entrenched, rather than less, in recent years) that therapies prove an effect on "hard outcomes" to get approval: things like heart attacks, amputations, or blindness. But people should ideally begin to receive rejuvenation biotechnologies well before patients are in near-term danger of such acute threats to life and health, making it extremely expensive and time-consuming to run a trial.

In 2012, it looked as if significant progress had been made on this front and several others during major stakeholder meetings amongst Alzheimer's disease (AD) patient and caregiver advocates, researchers, and FDA regulators. In particular, there was consensus on the need to work toward the development of new clinical trial designs and regulatory reforms to advance previously-untested combination therapies for AD into clinical testing. Draft guidance acknowledged that therapies for AD are unlikely to have substantial effects in "full-blown" dementia, because by that point, the brain has suffered either irreversible damage, or too many kinds of damage for any one therapy to be useful anymore. Then, despite having climbed up to the top of the diving tower, with advocates and scientists cheering at every step, FDA and pharma seemed to hesitate. The same FDA leaders who had previously expressed their openness to bold initiatives instead adopted a more conservative stance on using biomarkers as outcomes for early-stage disease.

This February, however, FDA finally took the plunge with a revised Draft Guidance, which would represent a tremendous step in the right direction if finalized as official FDA policy. The results of imaging tests or relevant biomarkers could then be considered sufficient to identify so-called "Stage 1" Alzheimer's patients as eligible candidates for clinical trials or new therapies, or to test existing therapies that had failed in people with frank AD. These "Stage 1" candidates are described in terms that identify people at an even earlier stage along the insidious path to dementia than the 2013 guidance: outwardly healthy but aging people without very-high-risk mutations or apparent cognitive or functional impairments, but who are nonetheless identified as being at higher risk than most. In short, these individuals would now be eligible to participate in trials of new and old therapies that might prevent them from ever tipping over into major cognitive impairments.

The use of biomarkers and imaging directly reflecting the key cellular and molecular damage driving AD and other neurodegenerative diseases of aging should be extended to testing of therapies in people who are in even greater danger, showing early signs of cognitive problems but still not suffering from full-fledged dementia. Analogously, biomarkers of the cellular and molecular damage that accumulates in our tissues as we age and that drives other age-related illness and debility should also be acknowledged as the best targets for new therapies that would prevent, arrest, and reverse those conditions. And because AD and other diseases of aging involve multiple kinds of cellular and molecular damage, it's critical that regulators allow the testing of combination therapies potentially capable of attacking multiple kinds of cellular and molecular aging damage, without first needing the constituent therapies to be tested individually.

Using a combination of ultrafast glutaraldehyde fixation and very low temperature storage, researchers have demonstrated for the first-time ever a way to preserve a brain's connectome (the 150 trillion synaptic connections presumed to encode all of a person's knowledge) for centuries-long storage in a large mammal. This laboratory demonstration clears the way to develop Aldehyde-Stabilized Cryopreservation into a 'last resort' medical option, one that would prevent the destruction of the patient's unique connectome, offering at least some hope for future revival via mind uploading. You can view images and videos demonstrating the quality of the preservation method for yourself at the evaluation page.

The Brain Preservation Foundation's (BPF) Large Mammal Brain Preservation Prize has been won by the cryobiology research company 21st Century Medicine (21CM) and lead researcher Robert McIntyre (an MIT-trained scientist who is now co-founder of the startup Nectome) and senior author Greg Fahy (Fellow of the Society for Cryobiology). The Prize required the successful preservation of synaptic connectivity across an entire pig brain in a manner compatible with centuries-long storage. To accomplish this, McIntyre's team scaled up the same procedure they used to previously preserve a rabbit brain, for which they won the BPF's Small Mammal Prize.

The first step in the ASC procedure is to perfuse the brain's vascular system with the toxic fixative glutaraldehyde, thereby instantly halting metabolic processes by covalently crosslinking the brain's proteins in place, and leading to death by contemporary standards (but not necessarily information-theoretic standards). Glutaraldehyde is sometimes used as an embalming fluid, but is more commonly used by neuroscientists to prepare brain tissue for the highest resolution electron microscopic and immunofluorescent examination. It should be obvious that such irreversible crosslinking results in a very, very dead brain making future revival of biological function impossible. So, it is reasonable to ask: "What is the point of a procedure that can preserve the nanoscale structure of a person's brain when biological revival is impossible?" The answer lies in the possibility of future non-biological revival.

A growing number of scientists and technologists believe that future technology may be capable of scanning a preserved brain's connectome and using it as the basis for constructing a whole brain emulation, thereby uploading that person's mind into a computer controlling a robotic, virtual, or synthetic body. The Brain Preservation Prize challenged the scientific community to develop a 'bridge' to that future mind uploading technology.

Traditional cryogenic preservation faces two conflicting challenges: rapid decay and ice crystal formation. The brain begins decaying immediately upon death, and therefore must be chilled quickly to halt the decay. However, the water contained in the brain is at risk of freezing into ice crystals, which would slice through the organic matter. Consequently, a process known as vitrification is preferred, in which water descends below freezing without crystallizing, instead forming what is called an amorphous solid. Vitrification is achieved by perfusing the brain with cryoprotectants before lowering the temperature.

However, the perfusion and chilling process, better performed slowly and carefully, cannot be allowed an optimal timeframe in which to occur due to the rapid decay. The necessary frenzied approach can, therefore, still result in tissue damage. Another problem arises as well. To expedite the process, the method currently used by cryonics organizations forces the cryoprotectants into the brain so aggressively, and at such high concentrations, as to actually osmotically pull water out of the cells. The brain is literally dehydrated like a raisin, and with similar results: significant shrinkage and deformation. It is frankly difficult to imagine the large-scale, region-to-region connective relationships of the brain surviving such trauma.

This problem of getting to low temperatures quickly underlies the most serious challenge currently facing the cryonics industry, and gives many neuroscientists pause about the best interpretation of the standard practice, namely that it is quite likely destroying the patients' brains, rendering future revival impossible. As such, cryonics "patients" or "subjects" might be better called by a different word: cadavers. To their credit, advocates for traditional cryonics acknowledge this problem, expressing their hope that futuristic technologies will repair both the micro- and macroscale damage. However, if the damage is truly information-destroying in nature, then no future technology, regardless of advancement, can ever recover the information. That fact is a fundamental trait of information theory.

So we can summarize the problem with current cryonics in the following way: Since the brain decays rapidly upon death, it must be chilled quickly to initiate preservation, but this hasty approach prevents adequate cryoprotectant perfusion, thereby risking partial ice crystal damage, while furthermore, the aggressive perfusion process used to accelerate the timeline additionally causes shrinkage and deformation.

Many people are wondering whether Alcor plans to adopt the "Aldehyde-Stabilized Cryopreservation" (ASC) protocol used to win the prize and what the win means for cryonics in practice. Alcor's position is as follows: We are pleased that vitrification, the same basic approach that Alcor Life Extension Foundation has utilized since 2001, is finally being recognized by the scientific mainstream as able to eliminate ice damage in the brain during cryopreservation. Alcor first published results showing this in 2004. The technology and solutions that Alcor currently uses for vitrification (a technology from mainstream organ banking research) were actually developed by the same company that developed ASC and has now won both the Small Mammal and Large Mammal Brain Preservation Prize.

Current brain vitrification methods without fixation lead to dehydration. Dehydration has effects on tissue contrast that make it difficult to see whether the connectome is preserved or not with electron microscopy. That does not mean that dehydration is especially damaging, nor that fixation with toxic aldehyde does less damage. In fact, the M22 vitrification solution used in current brain vitrification technology is believed to be relatively gentle to molecules because it preserves cell viability in other contexts, while still giving structural preservation that is impressive when it is possible to see it. For example, note the synapses visible in the images at the bottom of this page.

While ASC produces clearer images than current methods of vitrification without fixation, it does so at the expense of being toxic to the biological machinery of life by wreaking havoc on a molecular scale. Chemical fixation results in chemical changes (the same as embalming) that are extreme and difficult to evaluate in the absence of at least residual viability. Certainly, fixation is likely to be much harder to reverse so as to restore biological viability as compared to vitrification without fixation. Fixation is also known to increase freezing damage if cryoprotectant penetration is inadequate, further adding to the risk of using fixation under non-ideal conditions that are common in cryonics. Another reason for lack of interest in pursuing this approach is that it is a research dead end on the road to developing reversible tissue preservation in the nearer future.

Alcor looks forward to continued research in ASC and continued improvement in conventional vitrification technology to reduce cryoprotectant toxicity and tissue dehydration. We are especially interested in utilizing blood-brain barrier opening technology such as was used to win the prize.

Cellular senescence plays a complex role, both beneficial and deleterious, in biological processes such as embryonic development, wound healing, tissue regeneration, and tumor suppression, as well as age-related disorders. Senescent cells accumulate within aged tissues and at sites of age-related pathology in vivo, and potentially contribute to the age-related decline of tissue function by affecting the growth, migration and differentiation, of neighboring cells, impacting overall tissue architecture, and promoting chronic inflammation. Indeed, studies on both progeroid and naturally aged mice showed that selective elimination of p16Ink4a-expressing senescent cells increased healthspan and lifespan. Thus, the selective elimination of senescent cells (senolytics) or the disruptions of the senescence-associated secretory phenotype (SASP) program have been developed as potential therapeutic strategies against aging.

However, while p16Ink4a expression has been used as a classical senescence biomarker, no biomarker of senescence identified thus far is entirely specific to the senescent state. Thus, due to the lack of robust biomarkers of cellular senescence in vivo, the precise extent of senescent cell accumulation in aged animals and the functional outcome of such an accumulation, along with the exact target cells of, and removal by, senolytics, remain unclear. Surprisingly, a systematic multi-tissue in vivo study of senescence markers during aging has not been conducted in wild-type animals.

In the era of senolytics, it becomes imperative to develop robust biomarkers of senescence in vivo for preclinical trials, especially with several senolytics now nearing human clinical studies. As a first step, in this study we profiled the expression of a panel of known molecular markers of senescence in multiple tissues in mice at multiple ages, ranging from young (4 months) to very old (30 months). The results demonstrate that the secretory profiles and classical hallmarks of cellular senescence in aged tissues are highly variable and complex, suggesting that a systematic and concerted effort is needed to develop robust biomarkers of senescence for the identification, quantification, and monitoring of senescent cells in vivo.

The wide diversity in tissue-specific profiles we observed was striking. Nevertheless, the matrix metalloproteinase Mmp12 represents a robust SASP factor that showed consistent age-dependent increases in expression across all tissues analyzed in this study. It has been demonstrated that mice lacking Mmp12 are protected from vascular injury, M2 macrophage accumulation, and perivascular heart fibrosis. Together with our data, this finding suggests that Mmp12 upregulation with age has a deleterious impact on heart function.

In this study, we did not observe significant age-dependent upregulation of the prominent SASP cytokine Il6 in any tissue, although an upward trend was observed that was consistent in magnitude with previous observations in the heart and kidney. This modest age-related upward trend could be explained by a previous report which demonstrated that senescent cell-secreted IL-6 acts in an autocrine manner, reinforcing the senescent state, rather than inducing senescence or promoting dysfunction in neighboring cells.

The decreased expression of Il6 with age we observed in the hypothalamus could be indicative of a lack or loss of senescent cells in that tissue with age. In support of this interpretation, p16Ink4a expression was non-detectable in the hypothalamus at any age. Taken together, these results suggest that some other age-related process results in the increased expression of the pro-inflammatory factors Il1b, Mmp12, Cxcl1, and Cxcl2 observed in the aged hypothalamus. Conversely, p16Ink4a expression was upregulated with age in all other tissues analyzed, consistent with previous reports, and thus reinforcing the importance of p16Ink4a as a biomarker of tissue aging.

Questions still remain, however, regarding the ultimate identity of the cells targeted for senolytic elimination in previous studies, as it has been demonstrated repeatedly that p16Ink4a expression is not exclusive to senescent cells, and thus does not represent an unequivocal target for senolytic therapies. Interestingly, however, CDKN2A (the gene that encodes p16Ink4a) was one of the top human genes that exhibited elevated expression with age, in 6 out of 9 tissues, including subcutaneous adipose, tibial artery, lung, skeletal muscle, tibial nerve, and whole blood, as detected by RNA-seq analysis. Thus, utilizing p16Ink4a-expressing cells as a biomarker of tissue aging and a target of senolytic therapies could still prove to be an effective strategy in the future treatment of age-related diseases in humans.

Why did you choose Berlin and not California or elsewhere in the USA for the event?

Basically, because the suggestion came from our main German donor, Michael Greve, who is also the conference's main sponsor. Hard to argue with that!

Is SRF planning to make Undoing Aging into a recurring event, much like the Rejuvenation Biotechnology conferences in America?

We'll certainly be continuing to do both more science-centered events like Undoing Aging and the SENS Conferences, as well as more rejuvenation biotechnology industry-oriented events like the Rejuvenation Biotechnology series, but we haven't yet decided on the sequence and orientation of future meetings. We certainly want to maintain a strong conference presence in California, but it may be best to do that with smaller, more frequent events, such as the one we did with the California Life Sciences Association.

Recently, SRF has received significant donations amounting to over 7 million. What priorities does SRF plan to address with this money?

First and foremost, we will be gearing up our existing programs in mitochondrial gene replacement, scaling up glucosepane research, rejuvenation biotechnology against cytosolic aggregates, and so on. We will also be initiating new ones; those are still being discussed with potential extramural collaborators, but you can expect some announcements later this year. They will all be within the same seven-strand framework that has defined SENS since the beginning. And after having sometimes in the past allocated nearly all of our available research budget at the beginning of the fiscal year and thereby limiting our ability to take advantage of new opportunities that arose later in the year, we will be maintaining a research reserve fund so that we are always poised to get good work funded year-round.

For anyone reading this who is thinking about doing the same as our recent donors, I will just say that we are a very long way from running out of productive ways to invest more money.

Regarding the use of senolytics, are you concerned about their potential to remove highly specialized cells like cardiomyocytes, which do not divide or do so very slowly?

Cells that don't divide (like cardiomyocytes and neurons) are far less likely to become senescent in the first place than cell types that divide; many of the main drivers of senescence are related to cell division. In the specific case of cardiomyocytes, there's already significant evidence in rodents that senolytics improve cardiac function overall. However, there is some reason for concern here, which is why we're already working to develop the next generation of senescent cell ablation therapies. The selectivity of senolytic drugs for senescent cells comes from the fact that they target the activity or expression of genes involved in cell survival, on which senescent cells are much more reliant than healthy cells under normal, unstressed conditions. But during times in which the cell is under stress, normal cells also rely on those same pathways to carry them through and give them time to recover. Future therapies can target truly senescent cells more selectively, and SENS Research Foundation is helping to advance those next-generation senescent cell therapies, even as UNITY Biotechnology prepares for human testing, through our investment in Oisín Biotechnologies.

Senolytic drugs gave mice increased healthy lifespan in experiments. Given that every living organism produces senescent cells the same way, could this mean that it may translate to humans?

Interventions that lead to gains in median lifespan only in laboratory mice, with no corresponding effect on a robust maximum lifespan (tenth-decile survivorship), still need to be heavily discounted when speculating on effects in humans. Interventions that only affect median lifespan primarily affect deaths in the first half of the lifespan - and here there is a critical difference between mice in a lab and modern humans, for whom medicine has already eliminated many causes of such early deaths, from vaccines (which also impact late-life mortality by reducing lifelong inflammatory burden), to surgery, to antibiotics, to drugs that more obviously affect middle-aged people.

The force of this reasoning is somewhat attenuated in the case of interventions like senescent cell clearance, which actually repair aging damage, than with interventions affecting environmental or metabolic risk factors driving "premature" disease (obesity, inflammation, cardiovascular risk factors, environmental toxins, etc). Still, you have to assume that the effect on lifespan of any single damage-repair intervention in isolation will be modest, based on the principle of the "weakest link in the chain": all the links are weakening over time, and shoring up only one of them still leaves the rest of the links damaged and ready to shear, whereupon the whole chain is broken. To move the needle on lifespan in modern humans, we have to push back on all of the cellular and molecular damage of aging, not just one form.

Regarding the breakdown of extracellular aggregates, what will you do if the first wave of treatments using antibodies is unable to repair the whole system?

Certainly, it's guaranteed that no first-generation SENS therapy will be able to repair every single contributor to any given category of aging damage - and it doesn't have to. All we have to do to reach "longevity escape velocity" is to remove or repair the specific forms of cellular and molecular aging damage within each category that meaningfully restrict our lives to the extremes of current lifespans. During the extra decades of healthy life that we'll then enjoy, scientists can then work to identify the constraints that limit life- and healthspan to those newly-expanded horizons. Accordingly, all SENS therapies will need to be iteratively improved; we will want safer and more effective ways to repair the damage targeted by earlier iterations of rejuvenation biotechnologies and also to repair additional specific targets within each category. It's only once those first therapies are developed and in use that we'll know what their specific limitations will be

Have you reviewed you position that nuclear mutations matter only in cancer in light of recent research results suggesting that certain ominous mutations in hematopoietic stem cells increase the risk of developing not only blood cancers (50 fold) but dying of all causes by 40%?

The research on this "clonal hematopoiesis" phenomenon is certainly provocative but doesn't ultimately change our view on this question. Remember first that it has never been our position that nuclear mutations matter only in causing cancer; at a minimum, they also matter in causing apoptosis ("cellular suicide," which denudes the body of functional cells with age, most importantly stem cells) and cellular senescence (ditto, plus the baleful effects of the senescence-associated secretory phenotype). And then remember that SENS is fundamentally an engineering approach to aging, focused on practical solutions rather than acquiring a full understanding of mechanistic details. Our position has been, therefore, that all the effects of nuclear mutations that meaningfully constrain current human lifespan/healthspan can be obviated by removing, repairing, or obviating the effects of mutations that are relevant to our health over the course of currently-normal lifespans: clearing senescent cells, replacing cells lost to apoptosis and senescence and other causes, and making the body impervious to cancer.

In clonal hematopoiesis, blood stem cells with one of a small number of mutations gain a selective advantage over blood stem cells with other genotypes, which allows them to "take over" the stem cell compartment. This isn't exactly what an oncologist would call "cancer," but it is a clear case of "too many cells" caused by nuclear mutations proliferating at the expense of their neighbors, which fits the operational criteria for the oncoSENS category. And the periodic purging of all native bone marrow stem cells and their wholesale replacement with fresh, mutation-free, cancer-proof ones - which would immediately eliminate clonal hematopoiesis - is already planned to be the very first clinical phase of the whole body interdiction of lengthening of telomeres (WILT) plan to pre-emptively shut down cancer.

Has your position on the relevance of telomere attrition changed since you first devised SENS, especially in the light of the recent results with fibrosis and your involvement with AgeX Therapeutics?

No. Let's start with the big picture. Neither I nor anyone sensible has ever suggested that telomere attrition has no functional effects in aging: telomere attrition causes cells to become senescent and runs down the proliferative capacity of stem cells, amongst other things. Nor have I suggested that there wouldn't be some short-term health benefits to activating telomerase or telomerase gene therapy in aging animals or animal models of age-related disease. The issue is rather that those short-term benefits come with the longer-term (and sometimes not so long-term) risk of increased rates of cancer.

So, why don't we see a plague of excess cancers in animal studies that show the benefits of telomerase-based treatments? Depending on the study, it's one or more of several reasons. The most common one is that such studies are usually too short-term. A related issue is that many of these studies involving animal models of age-related disease are actually done in quite young animals that have been damaged in some way that simulates aspects of an age-related disease. Because such animals are still quite young, they haven't yet lived long enough to have accumulated a high burden of the kinds of mutations that predispose cells to become cancerous. A third reason why many animal studies of telomerase treatments don't result in high reported rates of cancer is that the animals may actually be deficient in telomerase to begin with, such that telomerase gene therapies actually just restore the normal activity of telomerase in the animals.

The solution to problems caused by age-related attrition of telomeres is not to juice up telomerase to lengthen them again in often-damaged stem cells, but to take telomerase out of the picture, purge those defective stem cells, and replenish stem cell pools periodically with cancer-proofed, pristine replacement cells that are unable to replicate out of control.

You have been engineering glucosepane-eating bacteria that use enzymes effectively 'gifted' to them. Have the enzymes you identified demonstrated specificity to glucosepane?

We can say that Dr. David Spiegel's SRF-funded lab at Yale has identified some candidates, but we can't go into the details at this time. Still, expect some news on the commercialization front in the glucosepane space in coming months.

Given the state of immunotherapy, and taking into account the rate of progress in the field, how confident are you that OncoSENS may be unnecessary?

The recent progress in cancer immunotherapy has certainly made me much more optimistic than I was five years ago that new cancer therapies might hold off cancer for more than a very small number of years - but not that it might make whole body interdiction of lengthening of telomeres (WILT) redundant. If we had all the other components of a comprehensive panel of rejuvenation biotechnologies assembled and deployed, ongoing progress with these therapies might well give us a slightly longer runway along the path to "longevity escape velocity" than I had expected at the time. But only slightly; within an all-too-short few additional years, I expect that without WILT, the surging rocket of "longevity escape velocity" will still run headlong into a wall of cancer until we have a way to definitively defeat its evolutionary engine of selection and replication. At present, WILT is the sole foreseeable approach to doing that.

Which rejuvenation treatments can we reasonably expect to reach the clinic first?

If you don't count stem cell therapies (some of which are in clinical use, but not as rejuvenation biotechnology), it's a race between ablating senescent cells with senolytics (with UNITY Biotechnology expected to perform their first-in-human trials early next year) and one of the many immunotherapies targeting the intracellular or extracellular aggregates that drive the neurodegenerative diseases of aging.

Primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC) are the most prevalent type of cholangiopathies, a diverse group of genetic and acquired disorders that affect the biliary population of the liver. PSC/PBC have variable prognoses but frequently evolve into end-stage liver disease, with limited treatment options. The aetiologies remain unclear, although a role of cellular senescence in the development of PSC/PBC has been suggested.

Senescence is an irreversible cell cycle arrest, driven by dominant cell-cycle inhibitors and characterized by the activation of the senescence-associated secretory phenotype (SASP). The SASP is a pro-inflammatory response that activates and reinforces the senescent phenotype in the surrounding cells, modulates fibrosis, and promotes regeneration. The SASP is composed by a variable set of secreted cytokines and chemokines, responsible for the beneficial and deleterious effects of senescence within the tissue. However, despite a number of studies suggesting a potential link between senescence and biliary disease, it has not been shown whether senescence is actually a driver of the damage rather than solely a consequence. We have therefore investigated the relationship between senescence and biliary disease, focusing on SASP-related mechanisms to explain part of the pathophysiology of PSC/PBC.

Here, we present a model of biliary disease, based on the conditional deletion of Mdm2 in bile ducts under the control of the Krt19 cholangiocyte promoter. In this model, senescent cholangiocytes induce profound alterations in the cellular and signalling microenvironment. The presence of senescent cholangiocytes in this model promotes ductular reaction, increases deposition of collagen, and impairs liver regeneration after injury. The presence of αSMA-positive cells in the proximities of the senescent cholangiocytes suggests that senescence might have a role in the development of fibrosis, characteristic of human PSC/PBC.

We suggest that senescence may contribute to the development of biliary disease through complementary mechanisms. First, through an impaired regenerative response of cholangiocytes, unable to compensate biliary damage, and second, through SASP expression, that can induce paracrine senescence in hepatocytes (thus diminishing the regenerative capacity of the liver during injury), promote collagen deposition, and enhance fibrogenesis. Overall, we have shown that cellular senescence is likely to be a driver of biliary injury by affecting the microenvironment, impairing liver parenchyma regeneration, and impairing biliary function.

Cells in metazoan species produce energy via oxidative phosphorylation, a process that requires a carbon source and oxygen (O2). O2 homeostasis is therefore of utmost importance and is maintained by intricate circulatory and respiratory systems. When the function of these is compromised, cells in the afflicted areas experience lower than optimal physiological O2 levels, a condition termed hypoxia. To cope with hypoxia, cells employ an evolutionarily conserved pathway controlled by hypoxia-inducible factors (HIFs).

Proteins encoded by hypoxia-inducible genes are functionally diverse, their primary role is to reprogram the cell towards survival under a hypoxic microenvironment and trigger specific physiological responses to help organisms adapt to conditions such as high altitude by inducing synthesis of erythropoietin, a hormone that stimulates production of red blood cells, or wound healing by activating secretion of angiogenesis-stimulating factors such as VEGF. This fine-tuned physiological response to hypoxia can, however, also be co-opted and contribute to age-related diseases.

For example: hypoxia and HIF-1 may participate in the pathogenesis of atherosclerosis; overactivation of the HIF pathway in cancer has raised significant interest in its targeting with small-molecule inhibitors; HIF-1 activates mPGES-1 gene expression in chondrocytes and contributes to the excessive catabolism underlying cartilage destruction and osteoarthritis. In the context of aging-associated diseases, more work is required to establish whether activation of HIF plays a causative role or is the consequence of some other underlying changes. In either case, there is evidence that targeting HIF-1, rather than its targets, e.g. VEGF, in at least some of these conditions may provide broader effect and eventually translate into greater therapeutic efficacy. As the number of age-associated maladies with activated HIF increases, it is rational to consider whether combining early detection with a HIF inhibitory pill could be of benefit for preventive treatment.

However, the relationship between HIF and aging is more complex. Genetic studies mainly in invertebrates have shown that HIF might control normal physiological processes that both promote and limit longevity. Life span extension imparted by stabilized HIF-1 occurs by a mechanism genetically distinct from both insulin-like signaling and dietary restriction. On the other hand, increased life span of C. elegans hif-1 deletion mutants was explained in terms of either activation of stress-regulated transcription factor DAF-16 or reactivating endoplasmic stress resistance downstream of mTOR. Further studies are warranted to understand the role of HIF-1 in longevity in mammals before merit of therapeutic modulation of its activity for age-related disease can be assessed.

What if we told you we could back up your mind? Imagine a world where you can successfully map and pinpoint a specific memory within your brain. Today's leading neuroscience research suggests that it is possible by preserving your connectome. The connectome is all the connections called synapses between neurons in your brain. Researchers are now learning to manipulate individual memories, building advanced brain prosthetics, and reverse-engineering the brain.

Our mission is to preserve your brain well enough to keep all its memories intact: from that great chapter of your favorite book to the feeling of cold winter air, baking an apple pie, or having dinner with your friends and family. We believe that within the current century it will be feasible to digitize this information and use it to recreate your consciousness. Our process of vitrifixation (also known as aldehyde-stabilized cryopreservation) has won the Brain Preservation Prize for preserving a whole rabbit connectome, and we are currently hard at work to scale our preservation process to larger brains.

We currently need help with developing tissue staining protocols for richer connectome imaging. We also are starting to develop a computational neuroscience program. If you are an interested research institution, or are interested in joining our engineering department, please get in touch.

Microglia are brain cells that help maintain the integrity and normal functioning of brain tissue. Dysfunction of these cells, as may occur in disease, is linked to neurodevelopmental disorders and neurodegenerative conditions. Aging is also associated with inflammation driven by microglia in specific regions of the brain, but it is unclear whether diet or lifestyle can influence this process.

Researchers investigated the impact of high- and low-fat diets on inflammation and microglial markers in a specific brain region - the hypothalamus - of 6-month-old mice. They further looked at the effect of low- or high-fat diets on the microglia of 2-year-old mice, which were also given a lifelong exercise regime (voluntary running wheel) or lifelong restricted diets (a 40% reduction in calories). "Aging-induced inflammatory activation of microglia could only be prevented when mice were fed a low-fat diet in combination with limited caloric intake. A low-fat diet per se was not sufficient to prevent these changes."

The researchers also found that exercise was significantly less effective than caloric restriction at preventing these changes, although work by others has shown that exercise is associated with reducing the risk of other diseases. There is still much more work needed to understand the meaning of these findings. In the study, mice were only given one type of diet throughout their lives. It remains unclear how changing between diets would alter these results - for example whether switching to a low-fat diet could undo the negative consequences of a high-fat, unrestricted diet. Further studies are also needed to determine how these changes correspond to the cognitive performance of the mice.

From the beginning of the 20th century to 2010, the life expectancy at birth for females in the United States increased by more than 32 years. However, new causes of death have emerged with changes in technology and the built environment (eg, the automobile and highways), emerging infections (eg, HIV), and behavior (eg, cigarette smoking). We analyzed trends in mortality rates among females at each decade from 1900 through 2010, focusing on major causes of death, and examined differences by age and by race. Historical trends may indicate future trends, contributing factors, opportunities for intervention when interventions are known, and research needs when they are not.

We analyzed all-cause unadjusted death rates (UDRs) for males and females and for white and nonwhite males and females from 1900 through 2010 in decadal years to indicate mortality burden. We analyzed UDRs for black persons beginning in 1970 when the data were first made available. We also computed age-adjusted all-cause death rates (AADRs) by the direct method using age-specific death rates and the 2000 US standard population.

From 1900 to 2010, the UDR among females in the United States decreased from 1,646.9 per 100,000 to 787.4 per 100,000, an overall decrease of 52.2%. Among males, the UDR decreased from 1,791.1 per 100,000 in 1900 to 812.0 per 100,000 in 2010, an overall decrease of 54.7%. The male UDR exceeded the female UDR in all decadal years except 2000; by 2010, the male excess had decreased to 24.6. From 1970 to 2010, death rates increased by 5.5% among white females and decreased by 22.5% among black females. Rates decreased by 20.3% among white males and by 38.9% among black males.

From 1900 to 2010, the AADR among females decreased from 2,410.4 per 100,000 to 634.9 per 100,000, a decrease of 73.7%. Among males, the AADR decreased from 2,630.8 per 100,000 in 1900 to 887.1 per 100,000 in 2010, a decrease of 66.3%. The male AADR exceeded the female AADR in all decades, with the greatest excess in 1970 at 570.7 per 100,000; the male excess was higher in 2010 than in 1900.

The 5 major causes of death for females in 1900 (46.3% of all deaths) were pneumonia and influenza (198.5 per 100,000), tuberculosis (187.8 per 100,000), enteritis and diarrhea (134.9 per 100,000), heart disease (133.7 per 100,000), and stroke (107.7 per 100,000). Of these causes, only heart disease and stroke were among the 5 major causes in 2010. In 2010, the 5 major causes (59.7% of all deaths) were heart disease (184.9 per 100,000), all cancers (168.2 per 100,000), stroke (49.1 per 100,000), chronic lower respiratory diseases (46.3 per 100,000), and motor vehicle accident (21.8 per 100,000).

Twenty years of the 30-year increase in female life expectancy from 1900 to 2010 occurred between 1900 and 1950, affected principally by social and environmental factors. During the first half of the 20th century, sanitation improved substantially, with greater benefits for blacks than for whites. Sanitation, the provision of clean drinking water and safe disposal of sewage and solid waste, affected rates of infectious and chronic diseases and was associated with almost half the total decrease in mortality rates in major US cities between 1900 and 1940, three-quarters of the decrease in infant mortality rates, and almost two-thirds of the decrease in child mortality rates.

Three major nonexclusive explanations for increased heart disease mortality rates from 1900 to 1950 are possible. First, as understanding of diseases improved, the apparent rise may have partly resulted from changes in classifying and assigning causes of death during the first half of the century. Second, the rise has also been attributed to a reduction in "competing causes" of death, most notably the reduction of deaths due to infectious and diarrheal diseases. Third, cigarette smoking was a major influence on trends in female chronic disease mortality rates. The prevalence of cigarette smoking among females rose rapidly in the 1930s, peaked from about 1965 to 1975, and decreased thereafter.

Much of the decrease in mortality rates among females in the past 110 years is attributable to improvements in major social and environmental determinants of health - education, income, housing, and sanitation. The rapid decrease in mortality rates from infectious by mid-century largely preceded the widespread use of antibiotics or immunization. The extent and specific causes of increased heart disease mortality rates among females in the first half of the century remain uncertain. The decrease of heart disease mortality rates during the second half of the century may be the result of multiple factors.

Trends in mortality rates during the past century reflect major patterns of health determinants. Sanitary and safety improvements along with understanding of and therapies for infectious diseases led to great reductions in infectious causes of death. With increasing longevity and more sedentary lifestyles, chronic diseases increased as major causes of death. Although some of these causes, particularly heart disease and stroke, decreased as a result of behavior change and effective health care, decreases in mortality rates are slowing.

For the crowd of mostly baby boomers the warning could not have been more dire: You're running out of time. "We can't sit still. We don't have the time to do that," bellowed Bill Faloon, the 63-year-old former mortician addressing them from the stage. To his left and right, giant screens projecting government actuarial tables reminded the group of the "projected year of our termination." Men of Faloon's age could expect to die in 2037. Any 83-year-old women in the room? They've got until only 2026. "Take that initiative," Faloon urged his audience of about 120 people who had flown in from as far as California, Scotland, and Spain. How? Paying to participate in a soon-to-launch clinical trial testing transfusions of young blood "offers the greatest potential for everyone in this room to add a lot of healthy years to their life," Faloon said. "Not only do you get to potentially live longer ... but you're going to be healthier. And some of the chronic problems you have now may disappear."

The symposium attendees complained about ailments that hadn't bothered them when they were younger: Back problems. Bad hips. The aftermath of a stroke. Parkinson's disease. Arthritis. Many of them voiced frustration with the medical establishment and pharmaceutical companies, which they said pay too little attention to fixing the root cause of disease. Others voiced fears of spending their final days hooked up to machines in a hospital bed.

This 195-a-head symposium was held last month in this wealthy beachside community. It offered a striking view of how promoters aggressively market scientifically dubious elixirs to aging people desperate to defy their own mortality. Eight independent experts reviewed informational handouts about the clinical trial, and all sharply criticized the study's marketing, design, and scientific rationale. "It just reeks of snake oil," said Michael Conboy, a cell and molecular biologist at the University of California, Berkeley, who's collaborated on studies sewing old and young mice together and transfusing blood between them. "There's no evidence in my mind that it's going to work."

Beyond the questionable science, participants have to pay big money to join the trial. Faloon, an evangelist of anti-aging research who cut a slim figure in his black suit and had the thick dark hair of a younger man, acknowledged during his talk that it would be "expensive" to sign up for the trial. People considering enrolling said they had been told they would have to pay 285,000. But the Florida physician running the trial said the final price tag is still being discussed in consultation with the Food and Drug Administration and is likely to change. To evaluate whether the experimental treatment is safe and whether it might be able to reduce frailty, it is planned to run a battery of baseline testing on each clinical trial participant before they get their first infusion of young plasma and then monitor their changes for two years: That means cognitive exams, questionnaires about their quality of life and their indicators of frailty, and tests to measure biomarkers believed linked with aging, such as telomere length and DNA methylation.

Experiments like this operate on the fringes of science, yet they have captured the public imagination. The trial wouldn't be the first to transfuse plasma from young donors into older people. A biotech startup called Alkahest, spun out from a Stanford lab, reported results in November from a placebo-controlled safety trial testing the effect of plasma from young donors on 18 patients with mild to moderate Alzheimer's. The patients who got the plasma didn't suffer serious side effects, but the group didn't see a statistically significant improvement in their scores on a widely used cognitive exam. Meanwhile, a company called Ambrosia recently completed a clinical trial that charged about 80 people over the age of 35 a sum of 8,000 to get an infusion of plasma from a donor between the ages of 16 and 25. Ambrosia plans later this year to try to publish those results in a peer-reviewed journal.

Clinical trials that charge enrollees to participate are ostensibly aimed at giving patients early access to promising therapies - often in the fields of stem cells or aging reversal - that are too unusual or have too little profit potential to get funding from traditional sources such as companies, foundations, or the National Institutes of Health. But critics worry that such trials too often exploit desperate patients, offering them false hope of restored health while doing little or nothing to advance scientific research.

The field seems to have agreed upon nine hallmarks of aging, do you believe it is feasible for us to one day be able to treat all of them?

Ten years ago I would have wondered how feasible this was, but based on the progress that has been made in the last few years I do think it is plausible that we will be able to address each of those pillars of aging and that by addressing these underlying mechanisms that drive aging we are going to be able to treat age-related disease. I think we have a tendency to view age-related diseases in silos but many of these disorders have a lot in common. I think we are on the brink of solutions to these problems, not in the next decades, but within years.

Could you briefly describe senescence and its impact on neurodegenerative diseases?

Senescence is a process in cells that stops cells from dividing, it gets activated when certain types of damage occurs. From an evolutionary perspective, cellular senescence is there to prevent damaged cells from undergoing the kind of rapid division that leads to tumors. This is great in the short term, but if they persist they give off toxic pro-inflammatory factors which can damage neighboring tissues. A lot of research in the field goes into understanding this process and what we can do to prevent this toxic effect.

For a long time the field of neuroscience ignored senescence because everyone just looked at the neurons, which don't divide. However we also started looking at the other cell types in the brain that do divide, namely astrocytes. They are a major support cell in the brain that also secrete growth factors that help neurons grow and communicate, they are also much more abundant than neurons. We then discovered that these cells do undergo senescence by looking at post-mortem tissue from Parkinson's disease brains and found astrocytes that had become senescent. We showed in animal models that if we could remove aggregations of these cells we could slow some of the disease process. This is very exciting because it means we can push this strategy forward into human clinical trials as it is a possible therapeutic strategy that has not been explored before. We were one of the first labs to look into this but now a lot of other labs around the world are jumping into cellular senescence to try and tackle age-related disorders.

You also explore the protein TFEB to boost lysosomal function and autophagy?

We were looking at a young-onset model of Parkinson's disease that has a mutation in the Parkin gene which marks damaged mitochondria for disposal via autophagy. We then learned that one of the major factors in that process is this transcription factor called TFEB, which is a master regulator of autophagy. This has now become a potential target for treating Parkinson's and Alzheimer's because these diseases are the result of protein build ups and dysfunctional mitochondria. It is thought that if we boost TFEB then cells will be able to better dispose of these protein build ups. We screened a number of compounds that boosts TFEB in the brains of these animals are now trying to move this forward to clinical trial.

Ever notice how a cut inside the mouth heals much faster than a cut to the skin? Gum tissue repairs itself roughly twice as fast as skin and with reduced scar formation. One reason might be because of the characteristics of gingival mesenchymal stem cells, or GMSCs, which can give rise to a variety of cell types. "This study represents the convergence of a few different paths we've been exploring. First, we know as dentists that the healing process is different in the mouth; it's much faster than in the skin. Second, we discovered in 2009 that the gingiva contains mesenchymal stem cells and that they can do a lot of good therapeutically. And, third, we know that mesenchymal stem cells release a lot of proteins. So here we asked, how are the gingival mesenchymal stem cells releasing all of these materials, and are they accelerating wound healing in the mucosal tissues?"

From earlier work it was clear that mesenchymal stem cells perform many of their functions by releasing signaling molecules in extracellular vesicles. So to understand what distinguishes mesenchymal stem cells in the gingiva from those in the skin, researchers began by comparing these extracellular vesicles between the two types. They found that the GMSCs contained more proteins overall, including the inflammation-dampening IL-1RA, which blocks a proinflammatory cytokine.

Next the team zoomed in to look at what might be controlling the release of IL-1RA and other cytokines. They had a suspect in the protein Fas, which they had earlier connected to immune regulation. They found that in gingival MSCs had more Fas than skin MSCs, and that mice deficient in Fas had reduced IL-1RA as well as reduced secretion of IL-1RA. Further molecular probing revealed that Fas formed a protein complex with Fap-1 and Cav-1 to trigger the release of small extracellular vesicles. To identify the connection with wound healing, they examined wound tissue and found that IL-1RA was increased in GMSCs around the margins of wounds. Mice lacking IL-1RA or in which the protein was inhibited took longer to heal gingival wounds. In contrast, when the researchers isolated IL-1RA that had been secreted from GMSCs and injected it into wounds, it significantly accelerated wound healing.

These findings may have special significance for people with diabetes, a major complication of which is delayed wound healing. In the study, the researchers found that GMSCs in mice with diabetes were less able to secrete extracellular vesicles compared to GMSCs in healthy mice, and their GMSCs also had less IL-1RA secretion. Introducing extracellular vesicles secreted from the GMSCs of healthy mice reduced wound healing time in diabetic mice. "Our paper is just part of the mechanism of how these stem cells affect wound healing, but I think we can build on this and use these cells or the extracellular vesicles to target a lot of different diseases, including the delayed wound healing seen in diabetic patients."

Young, resting neural stem cells in the brains of mice store large clumps of proteins in specialized cellular trash compartments known as lysosomes. As the cells age, they become less proficient at disposing of these protein aggregates, and their ability to respond readily to "make new neurons" signals wanes. Restoring the ability of the lysosomes to function normally rejuvenates the cells' ability to activate, the researchers found. "We were surprised by this finding because resting, or quiescent, neural stem cells have been thought to be a really pristine cell type just waiting for activation. But now we've learned they have more protein aggregates than activated stem cells, and that these aggregates continue to accumulate as the cells age. If we remove these aggregates, we can improve the cells' ability to activate and make new neurons. So if one were able to restore this protein-processing function, it could be very important to bringing older, more dormant neural stem cells 'back to life.'"

Researchers isolated several populations of cells for study from the brains of both young and old mice, including resting neural stem cells, activated neural stem cells, and the neural cell progenitors that arise from activated stem cells. They found that resting stem cells expressed many lysosome-associated genes, while activated stem cells expressed genes associated with a protein complex involved in protein destruction called a proteasome. Strict control of production and disposal allows cells to maintain the necessary protein inventory to carry out needed cellular functions.

"The fact that these young, pristine resting stem cells accumulate protein aggregates makes us wonder whether they actually serve an important function, perhaps by serving as a source of nutrients or energy upon degradation." Old resting stem cells express fewer lysosome-associated genes and begin to accumulate even higher levels of protein aggregates. "It's almost as if these older cells lose the ability to store, or park, these aggregates. We found that artificially clearing them by either activating lysosomes in older cells or subjecting them to starvation conditions to limit their protein production actually restored the ability of these older resting stem cells to activate. We'd like to know whether the aggregated proteins are the same in the young and old cells. What do they do? Are they good or bad? Are they storing factors important for activation? If so, can we help elderly resting stem cells activate more quickly by harnessing these factors? Their existence in young cells suggests they may be serving an important function."

As someone who is fully supportive of the ultimate goals of the cryonics enterprise, but still views the current state of the practice with some degree of skepticism, I make a point of acquainting myself with the latest evidence regarding the quality of cryonics procedures and their ability to preserve the foundations of a person's identity through time. Over the past two years or so, I have increasingly seen a recent achievement by 21st-Century Medicine (21CM) cited by some cryonics supporters as demonstrating the scientific validity of those procedures: namely 21CM's research on aldehyde-stabilized cryopreservation (ASC). This new technique has allowed them to win the Technology Prize awarded by the Brain Preservation Foundation (BPF) by demonstrating excellent preservation of brain ultrastructure. Were I to follow this line of reasoning, I could happily set aside my concerns about the adequacy of today's cryopreservation procedures, which had now been verified by scientific experts; the proper focus would now need to be on how to responsibly introduce those procedures into a clinical setting, for patients at the end of their lives who might request them.

It turns out, however, that things are not so simple. ASC is no doubt a step forward for the field of brain banking, and as its name indicates, it it is indeed a form of cryopreservation, since it involves vitrification of the brain at -135°C. Nonetheless, ASC does not count as cryonics, insofar as it uses a fixative solution prior to vitrification and cooling, which could potentially preclude revival of the original biological brain (an essential part of cryonics as traditionally understood). And indeed, biological revival with the help of future technology is not a priority for the Brain Preservation Foundation (BPF)'s president, Dr. Kenneth Hayworth. Rather, he envisages brain preservation as conducive to life extension via mind uploading: a process that would involve cutting the preserved brain into thin slices, scanning each slice, and feeding the resulting data to an advanced computer that would thereby be able to map out the entire network of neural connections in the person's original brain, and ultimately to emulate that person's mind. This is quite different from cryonics.

The BPF's commitment to holding brain preservation research to the highest standards of scientific rigour is laudable, and worth emulating. Nonetheless, for those interested in brain preservation with a view to enabling life extension, supporting cryonics-specific research remains the safer bet. We should not simply rely on the BPF's approach if our goal is to try and save those whom medicine in its current state cannot restore to life and health.

To see why this is so, let us begin by noting the two main philosophical theories of personal identity through time that are relevant when discussing the respective merits of cryonics and mind uploading in this context. The first one, which we can call the "Physical Continuity" (PhyCon) theory, asserts that a person is identical with the physical substratum from which her mind emerges: that is to say, her brain, with its intricate web of neurons and synaptic connections. The second relevant theory can be referred to as the "Psychological Continuity" (PsyCon) theory. Roughly speaking, it says that you are to identical with the set of psychological features (memories, beliefs, desires, personality traits, etc.) that constitutes your mind. On this view, preserving you after you have been pronounced dead requires ensuring the persistence of enough of those psychological features, in an embodied mind of some sort (but one that need not be embodied in your current biological brain).

If that is the case, what is the prudent choice to make for those who wish to promote life extension through brain preservation? I submit that traditional cryonics is the more prudent option to pursue. This can be demonstrated using a simple argument that considers what the implications are if we assume that PhyCon and, respectively, PsyCon are true. Suppose first that PhyCon is true. If so, a cryonics procedure carried out properly will save a person's life, whereas using a technique like ASC that compromises the brain's potential for viability, followed by destructive scanning and uploading, will kill that person. If PsyCon is true, on the other hand, both methods can ensure survival. Indeed, adequate cryonic preservation of a person's brain would also preserve the ultrastructure grounding the various psychological features that defined that person.

None of this is meant to imply that the work of the BPF is without merit. On the contrary, the Foundation's approach demonstrates a number of virtues that can provide a model for the cryonics movement to follow. These include a commitment to rigorously and impartially evaluating the quality of brain preservation procedures, in accordance with the standards of scientific peer-review. Another example is the BPF's successful effort at crowdfunding its incentive prizes for brain preservation research, such as the two prizes won by 21CM.