MicroRNA Inhibition to Enhance Skin Healing

These are the opening years of a period of barnstorming and experimentation in the modification of regenerative processes. A growing mountain of knowledge is under construction for all of the most important aspects of regeneration: stem cells, cellular senescence, immune cell activity, and so forth. The cost of tools used in the biotechnology field is falling even as the capabilities of those tools increase dramatically. Exploration of the biochemistry of regeneration has never been as easy and as cheap as it is today. A tipping point has either passed or lies just ahead, with the result being an expanding diversity of ways to adjust the self-repair of tissues - and to perhaps restore a more youthful, healthy degree of healing where it is impaired by aging, by inflammation, or by metabolic diseases such as diabetes.

One of the important challenges found in most areas of modern medical research is targeting. As it becomes possible to edit genes and selectively increase or decrease the amounts of specific proteins inside cells, it is also becoming increasingly important for such changes to be localized. The amount of a given protein in circulation is a switch or a dial in the machinery of cellular metabolism, but the same protein can have radically different roles in different tissue types. So while a global adjustment throughout the body is in many cases quite feasible to achieve today, it is in many cases a bad idea to try it. A beneficial change in one tissue might even prove fatal in another. Thus a wide range of approaches are at various stages of development when it comes to to targeting therapies to specific tissues, as the better and more reliable the targeting mechanism, the more options become available as a basis for medical development. The paper I'll point out today is one example of the type:

New hope for slow-healing wounds

MicroRNAs are small gene fragments which bond onto target structures in cells and in this way prevent certain proteins from forming. As they play a key role in the occurrence and manifestation of various diseases, researchers have developed what are known as antimiRs, which block microRNA function. The disadvantage of this approach is, however, that the blockade can lead to side effects throughout the entire body since microRNAs can perform different functions in various organs. Researchers have now solved this problem.

The researcher have developed antimiRs that can be activated very effectively over a limited local area by using light of a specific wavelength. To this purpose, the antimiRs were locked in a cage of light-sensitive molecules that disintegrate as soon as they are irradiated with light of a specific wavelength. As a means of testing the therapeutic effect of these new antimiRs, the researchers chose microRNA-92a as the target structure. This is frequently found in diabetes patients with slow-healing wounds. They injected the antimiRs in the light-sensitive cage into the skin of mice and then released the therapeutic agent into the tissue with the help of light. Together the research groups were able to prove that pinpointed activation of an antimiR against microRNA-92a helps wounds to heal.

"Apart from these findings, which prove for the first time that wound healing can be improved by using antimiRs to block microRNA-92a, our data also confirms that microRNA-92a function is indeed only locally inhibited. Other organs, such as the liver, were not affected." The researchers now want to see whether they can also expand the use of light-inducible antimiRs to the treatment of other diseases. In particular they want to examine whether toxic antimiRs can attack tumors locally as well.

Light-inducible antimiR-92a as a therapeutic strategy to promote skin repair in healing-impaired diabetic mice

MicroRNAs (miRs) are small non-coding RNAs that post-transcriptionally regulate gene expression by binding to targeted mRNAs and thereby inducing degradation or blocking its translation. MiRs have important functions in different pathophysiological processes and diseases. Therefore, targeting miRs by application of specific miR inhibitors might have great therapeutic potential. MiRs can be inhibited by different types of antisense RNAs (antimiRs). Such antisense oligonucleotides are relatively easily taken up by detoxifying organs such as the liver or kidney, but uptake in other organs such as the muscle or brain tends to be limited. Local delivery or activation may be necessary to augment the biological functions of antimiRs in the target tissue and reduce systemic toxicity. Local activation might also avoid unwanted side effects of antimiRs, since miRs have diverse functions in different tissues.

Several targeting strategies have been experimentally used including the linking of miRs or antimiRs to aptamers, nanoparticle- or microparticle-mediated delivery and cell type-specific delivery by viral vectors as well as attempts of local delivery by mechanical tools, for example, catheters. In addition, we and others have developed photoactivatable antimiRs by attaching photolabile protecting groups (cages) to the nucleobases that temporarily inhibit duplex formation with the target miR, thereby allowing an excellent on/off behaviour upon irradiation.

However, the therapeutic in vivo use of light-activatable antimiRs has been unclear. Therefore, we tested whether light-activatable antimiRs directed against miR-92a can be used to locally augment impaired wound healing in diabetic mice. Inhibition of miR-92a was previously shown to improve angiogenesis and recovery after ischaemia; however, its regulation and function during wound healing, a process that is dependent on the angiogenic response, is unknown. Here we show that light-activatable antimiR-92a efficiently downregulate miR-92a expression leading to target gene derepression in the murine skin, thereby improving diabetic wound healing by stimulating cell proliferation and angiogenesis.

In Search of Ways to Induce Heart Regeneration

The heart is one of the least regenerative organs in mammals, but this actually isn't the case in every circumstance; some types of injury and stimulus do produce a greater regenerative response, even if nowhere near as large as desired. The suspicion is that the capacity for greater regenerative exists, but is muted in some way, perhaps by cancer suppression mechanisms such as the ARF gene. Thus researchers are hunting for clues in the biochemistry of more regenerative species, such as zebrafish and salamanders, in order to discover whether or not mammalian heart cells can be adjusted to heal injuries more readily. Another place to look, as illustrated here, is in the biochemistry of the few circumstances in which mammalian hearts are known to regenerate more readily.

In adult mammal hearts, cardiomyoctyes do not proliferate following damage, like that caused by myocardial infarction. However, the inability to proliferate is not true for all animals, and even in mammals, cardiomyocyte proliferation is known. Neonatal cardiomyocytes proliferate, and the cardiomyocytes of zebrafish proliferate through adulthood, for example. However, hearts recover well from myocarditis, suggesting adult cardiomyocytes can proliferate in certain conditions. Myocarditis describes inflammation of the heart, usually in response to a viral infection. Many patients will suffer from cardiac dysfunction but recover naturally, largely because of factors activated by the immune response.

Researchers prepared mice with myocarditis to investigate this recovery under the assumption that proliferation was not the cause. "We hypothesized that immune factors are responsible. STAT3 is a transcription factor with cardioprotective effects. But in our study, we found it also has cardioproliferative effects. In myocarditis, we found that STAT3 was activated and that cardiomyocytes could proliferate. But when we knocked-out STAT3, the proliferation was lost." For cells to proliferate, they must enter the cell cycle. Following birth, mammalian cardiomyoctyes exit the cell cycle. The researchers found that in myocarditis, cardiomyoctyes could reenter the cycle to proliferate and recover heart function.

In myocarditis about 1% of cardiomyocytes express Aurora B, an indicator of cells entering the cell cycle, but in myocardial infarction (heart attacks) only 0.01% of cardiomyocytes expressed Aurora B. The team also found that the activation of STAT3 and expression of cell cycle markers could be stimulated by the immune protein interleukin 11, suggesting a possible cytokine means to initiate the proliferation. "These were very surprising findings. We still have much to learn about how the inflammatory signaling can promote heart regeneration. Medicines that activates these pathways could lead to new cardiac drugs."

Link: http://resou.osaka-u.ac.jp/en/research/2017/20170503_1

An Example of the Early Stages of Antisenescence Drug Development

The presence of senescent cells is a contributing cause of aging; the number of such cells grows over time as a consequence of the normal operation of metabolism, and collectively they cause considerable harm to tissue and organ function. The most important lines of research on cellular senescence aim at the production of senolytic therapies capable of removing these unwanted cells, but a sizable fraction of the researchers involved in this part of the field are more interested in antisenescence treatments, those that minimize the bad behavior of these cells, or reduce the number of cells that become senescent.

It would perhaps be more accurate to say that there is an ongoing reassessment of protein and drug candidate libraries in order to categorize known effects in terms of their influence on cellular senescence; all too much of medical research involves repurposing of existing drugs where there is any small positive outcome rather than building better technologies from first principles. When it comes to looking at existing outcomes from the drug and protein libraries in search of modifications to the behavior of senescent cells, my impression is that this is a road to marginal therapies only, those that slightly reduce the impact of senescent cells rather than solving the problem completely. This is a widespread problem in the research community, in which too many people are devoting resources to projects that are unlikely to have a sizable impact on aging.

Kallistatin, an endogenous protein, protects against vascular injury by inhibiting oxidative stress and inflammation in hypertensive rats and enhancing the mobility and function of endothelial progenitor cells (EPCs). We aimed to determine the role and mechanism of kallistatin in vascular senescence and aging using cultured EPCs, streptozotocin (STZ)-induced diabetic mice, and Caenorhabditis elegans (C. elegans). Human kallistatin significantly decreased TNF-α-induced cellular senescence in EPCs, as indicated by reduced senescence-associated β-galactosidase activity and plasminogen activator inhibitor-1 expression, and elevated telomerase activity. Kallistatin blocked TNF-α-induced superoxide levels, NADPH oxidase activity, and microRNA-21 (miR-21) and p16INK4a synthesis. Kallistatin prevented TNF-α-mediated inhibition of SIRT1, eNOS, and catalase, and directly stimulated the expression of these antioxidant enzymes.

Moreover, kallistatin inhibited miR-34a synthesis, whereas miR-34a overexpression abolished kallistatin-induced antioxidant gene expression and antisenescence activity. Kallistatin via its active site inhibited miR-34a, and stimulated SIRT1 and eNOS synthesis in EPCs, which was abolished by genistein, indicating an event mediated by tyrosine kinase. Moreover, kallistatin administration attenuated STZ-induced aortic senescence, oxidative stress, and miR-34a and miR-21 synthesis, and increased SIRT1, eNOS, and catalase levels in diabetic mice. Furthermore, kallistatin treatment reduced superoxide formation and prolonged wild-type C. elegans lifespan under oxidative or heat stress, although kallistatin's protective effect was abolished in miR-34 or sir-2.1 (SIRT1 homolog) mutant C. elegans. Kallistatin inhibited miR-34, but stimulated sir-2.1 and sod-3 synthesis in C. elegans. These in vitro and in vivo studies provide significant insights into the role and mechanism of kallistatin in vascular senescence and aging by regulating miR-34a-SIRT1 pathway.

Link: http://dx.doi.org/10.1111/acel.12615

The Degree to which Vascular Stiffness and Hypertension are Secondary Aging

Today's research results provide data to indicate the degree to which vascular stiffening and hypertension across today's population are the consequences of avoidable lifestyle choices and environmental factors rather than consequences of unavoidable processes of damage. The study suggests that cardiovascular aging can be influenced considerably until a comparatively late age, and in this it may be one of the most malleable of the many distinct aspects of aging. All of aging is some mix of primary and secondary contributions, varying widely between organs and circumstances. One can think of primary aging as the list of cell and tissue damage described in the SENS program, causes of aging that occur as a consequence of the normal, healthy operation of metabolism. Secondary aging, on the other hand, is some mix of being overweight, living a sedentary lifestyle, exposure to a toxic environment that spurs inflammation, exposure to pathogens that wear down the immune system, and so forth. Choices and environment, in other words - things that are optional or at least to some degree avoidable, and which act to accelerate the pace at which fundamental damage accrues.

Raised blood pressure, hypertension, is a good marker for cardiovascular mortality, and lowered blood pressure obtained through pharmacology and lifestyle changes have resulted in a considerable reduction in that rate of death over the past few decades. There is good evidence for hypertension to be largely caused by the stiffening of blood vessels, and the changes that loss of elasticity produces in the systems of feedback that guide blood flow and heart activity. Stiffening of blood vessels in turn is caused by a range of mechanisms, including calcification, the inflammatory activity of senescent cells, and the presence of cross-links in the extracellular matrix of blood vessel walls. Some of these contributing factors are more easily adjusted than others - levels of inflammation, for example. So while on the one hand it is encouraging to see that presently available courses of action can make some difference, on the other hand it all still ends in the same place, at least until such time as rejuvenation therapies after the SENS model of damage repair are developed. The manifestations of aging are produced by damage, and until that damage can be effectively repaired, there is only so far you can go with an optimal approach to secondary aging.

Common artery problems as you age may be avoided or delayed, study shows

Potentially dangerous artery problems considered common as people age may actually be avoided or delayed well into the senior years, according to new research. The risk for high blood pressure and increased blood vessel stiffness, which both increase the risk of heart disease, may be reduced with a healthy lifestyle. There's a catch, though: It takes a lot of work. "What we are showing is that, even in a population acculturated to a Western lifestyle, it is possible to maintain a healthy vasculature over age 70. But it is extremely challenging."

The researchers defined healthy vascular aging as absence of high blood pressure and having vascular stiffness of the arteries of a person 30 years or younger. In a study of nearly 3,200 people ages 50 and older from the Framingham Heart Study, researchers found 566 individuals, or nearly 18 percent, met the requirements for healthy vascular aging. Most were in the youngest group, ages 50 to 59, where about 30 percent had the measures of healthy vascular aging. Among those 70 and older, only 1 percent had the soft arteries of a 30-something. "People with healthy vascular aging were at a 55 percent lower risk of developing cardiovascular disease. Those results are mainly a result of the softness of their arteries." Most importantly, having a low body mass index and being free of diabetes seemed to be associated with healthier arteries into old age. Other factors, including use of lipid-lowering drugs, also made a difference.

Prevalence, Correlates, and Prognosis of Healthy Vascular Aging in a Western Community-Dwelling Cohort

Hypertension and increased vascular stiffness are viewed as inevitable parts of aging. To elucidate whether the age-related decrease in vascular function is avoidable, we assessed the prevalence, correlates, and prognosis of healthy vascular aging (HVA) in 3,196 Framingham Study participants aged ≥50 years. We defined HVA as absence of hypertension and pulse wave velocity of less than 7.6 m/s. Overall, 566 (17.7%) individuals had HVA, with prevalence decreasing from 30.3% in people aged 50 to 59 to 1% in those aged ≥70 years.

In regression models adjusted for physical activity, caloric intake, and traditional cardiovascular disease (CVD) risk factors, we observed that lower age, female sex, lower body mass index, use of lipid-lowering drugs, and absence of diabetes mellitus were cross-sectionally associated with HVA. Although HVA is achievable in individuals acculturated to a Western lifestyle, maintaining normal vascular function beyond 70 years of age is challenging. Although our data are observational, our findings support prevention strategies targeting modifiable factors and behaviors and obesity, in particular, to prevent or delay vascular aging and the associated risk of CVD.

Impaired Insulin Signaling Outside the Nervous System Fails to Produce Life Extension in Mice

This paper might be taken as an interesting sidebar to the large amount of research into the influence of insulin signaling on the pace of aging, a part of the way in which the operation of cellular metabolism determines natural variations in longevity. Many of the methods of slowing aging in laboratory species involve some form of impairment in insulin signaling, usually implemented globally in all tissues and throughout the entire life span via the use of genetic engineering to create an altered lineage of animals. Whether such alterations are global and when in life they occur matters, however. Further, most investigations have taken place in lower species such as flies and worms rather than in mammals. Here, researchers demonstrate that impaired insulin signaling achieved in adulthood and only in tissues other than the nervous system has no positive effect on mammalian life span.

Longevity is determined by a complex interaction between environmental and genetic factors. One of the most successful interventions to delay the onset of aging-associated diseases and increase life expectancy is the chronic reduction in food intake, that is calorie restriction (CR). One of the mechanisms through which CR may extend lifespan is through reduced activation of insulin/IGF1 signalling. Following food intake, insulin is released and acts via the insulin receptor (IR) to facilitate the metabolism of glucose. Altering glucose metabolism via the inhibition of glycolysis or the impairment of insulin/IGF1 signalling consistently extends lifespan in Caenorhabditis elegans and Drosophila melanogaster. However, the effect of insulin/IGF1 signalling cascade inhibition on longevity in mammals is less clear.

In mammals, prenatal complete ablation of the insulin receptor (IR) or IGF1 receptor (IGF1R) globally shortens lifespan, whereas ablation of the IR in some tissues such as the liver and pancreas induces a diabetic phenotype. The IR appears to play a central role in normal development, and central nervous system (CNS) IR expression in adulthood is required for the maintenance of glucose homeostasis. This suggests that the absence of the IR in peripheral tissues during early development, and in the CNS during adulthood may contribute to reduced lifespan and diabetic phenotype seen in some prenatal IR knockout models. Interestingly, deletion of the IR, which primarily targets adipose tissue but may also act on several other nervous system and peripheral tissues, as well as the disruption of the insulin/IGF1 signalling pathway downstream of the IR, is effective in prolonging lifespan in rodents. Furthermore, some genetic variations in the insulin/IGF1 pathway are associated with increased human lifespan expectancy. This is consistent with the requirement of the IR to facilitate metabolism of glucose in peripheral tissue and indicates that some degree of IR signalling is probably required during development and adulthood for normal life expectancy.

In all of these studies, however, the disruptions in insulin signalling were created using systems that were active from early developmental stages, so little is known about the effects of altered insulin signalling on longevity when the alteration is limited to adulthood. We have previously shown that partial disruption of the IR in mammalian cells causes adaptations, and similar adaptations extend the lifespan of C. elegans. In the present study, we determined the effect of partial or complete adult-induced peripheral tissue IR disruption on metabolism and lifespan of mice. Complete peripheral IR disruption resulted in a diabetic phenotype with increased blood glucose and plasma insulin levels in young mice. Although blood glucose levels returned to normal, and fat mass was reduced in aged mice, their lifespan was reduced. By contrast, heterozygous disruption had no effect on lifespan. This was despite young male mice showing reduced fat mass and mild increase in hepatic insulin sensitivity. In conflict with findings in metazoans like Caenorhabditis elegans and Drosophila melanogaster, our results suggest that heterozygous impairment of the insulin signalling limited to peripheral tissues of adult mice fails to extend lifespan despite increased systemic insulin sensitivity, while homozygous impairment shortens lifespan.

Link: https://dx.doi.org/10.1111/acel.12610

A Potential Target to Prevent One Class of Autoimmune Diseases

Autoimmune diseases, in which the immune system malfunctions to attack the patient's own tissues, are a challenge to investigate. The immune system is enormously complex, and making a definitive determination of the specific problems in its regulation that cause autoimmunity has yet to be achieved for most forms of autoimmune disease. Fortunately there has been some progress, such as the identification of age-associated B cells as necessary in the development of autoimmunity, and here the determination that JunB is critical to some autoimmune diseases. In both cases, these mechanisms might be targeted to produce broadly effective therapies. Yet even in absence of any useful targets, if there was a way to safely destroy all immune cells - without the use of damaging chemotherapeutic drugs that cause significant side-effects and mortality - then all autoimmune diseases could be cured. Malfunctions are a matter of state, and that state is stored in the immune cells themselves; if they are all removed, and the immune system allowed to repopulate itself from scratch, then this effectively restores a pristine and correctly functioning state.

Most of the current treatments against auto-immune diseases require to shut down major parts of the immune system, inhibiting desirable immune responses and, leaving the patient vulnerable to potentially life-threatening bacterial and viral infections. Such a drastic solution is required because until now scientists had yet not fully identified a different mechanism in these rogue cells they could use as a selective target - the known genetic material was common between healthy and rogue cells. But researchers have reported a previously undiscovered role for a known molecule - named "JunB" - and its associated gene: JunB seems to be essential for a specific type of white blood cell to turn toxic.

The scientists were investigating T Helper white blood cells, which coordinate the immune system response by secreting a diverse range of communication signals in the shape of molecules called interleukins. JunB operates in 'T Helper 17' cells, a subdivision that specifically promotes the initial immune response against an infection. But sometimes, these T Helper 17 cells turns rogue and become toxic for our guts and joints. "We have a lot of T Helper 17 cells in our guts. They have three major impacts on our body: first to maintain a healthy gut and second to deal with bacterial and fungi infections. The third is their toxicity leading to auto-immune diseases, which is something we want to avoid."

The scientists studied the process in which T-Helper 17 cells become toxic. One of the immune system communication molecules - interleukin 23 - is required to "wake up" T-Helper 17 cells during an infection and make it start fighting the invaders. But interleukin 23 is a double-edged sword: it also responsible for sometimes triggering the same T Helper 17 cell to turn rogue. For T helper 17 cells to hear the wake-up call, they need to display interleukin 23 receptors on their surface, which means the corresponding gene - usually switched off - needs to be activated. Finding a way to stop this interleukin 23 receptor gene from being activated is potentially key to shut down the entire process. And this is where JunB, the focus of this research, comes into play.

JunB is a transcription factor, which means it regulates - switches on and/or off - the activity of a gene or a group of genes in the cell's DNA. Researchers identified JunB by systematically checking transcription factors in the T Helper 17 cell DNA. For this purpose, they would "knock down" - meaning disrupt the gene DNA sequence - the genes for each transcription factor one by one. For each knocked down gene, they checked if the T Helper 17 cell still display its interleukin-23 receptors. When they knocked down JunB, they realized the T Helper 17 cells were no longer displaying interleukin 23 receptors and were unable to turn rogue. Moreover, mice in which T Helper cells lacked JunB were incapable of developing T Helper 17-related auto-immune diseases. An exciting part of this research is that T Helper 17 cells deprived of JunB are still able to accumulate in the gut and likely to cope and fight infections. Therefore, if scientists design a drug able to target JunB specifically, it should prevent T Helper 17 cells from turning rogue without impacting the immune system as a whole.

Link: https://www.oist.jp/news-center/press-releases/subduing-rebellion-unmasking-rogue-cells-immune-system

Reviewing the Measurement of Biological Age in Humans

To go along with a recent open access paper on progress in the development of biomarkers of aging, I though I'd point out another top to bottom review of the presently available means to measure aging in humans. This is an especially important topic now the first rejuvenation therapies, those based on targeted removal of senescent cells, are close to availability. Most of the drug candidates are in fact available now to some degree for the adventurous who would like to try self-experimentation. But if you self-experiment with a potential rejuvenation therapy, how do you know that it works? If you cannot answer that question, you should certainly hold back rather than forge ahead.

Since there are a number of distinct root causes of aging, at this stage in the field a given therapy will only target one of them, these first therapies will most likely be only partially effective, and biology is complicated and contrary, it would be entirely possible to try something and experience no obvious immediate outcome, whether or not it worked in the strict sense. Further, while one can measure the outcome appropriate to the therapy, for example the degree to which it does in fact remove lingering senescent cells, proof is still required to show that this outcome did in fact produce rejuvenation. Thus other measures of function and health are needed, and those must be generally agreed upon across the research community to accurately reflect the state of biological age.

While there are plenty of options to form the basis for a generally applicable measure of biological age, ranging from metrics built of a combination of simple measure such as grip strength to characteristic age-related changes in the patterns of DNA methylation, the "generally agreed upon" part of the process has yet to happen. Firstly there is the matter of proving that a given metric is actually useful, something that will probably only happen in conjunction with proving that the first rejuvenation therapies are in fact rejuvenation therapies. Secondly, the research community tends to move very slowly on the matter of establishing standards of any sort, and the more possibilities there are to debate and refine, the slower that progression.

This paper is somewhat illustrative of that point, given the scope and length of work that the authors foresee for the future. I suspect that things will move more rapidly than the future that these researchers envisage, however. My prediction is that the marketplace of biotech companies and clinics will settle on one or more forms of DNA methylation assessments of biological age as good enough at the cost required for their implementation, and move ahead to standardize on them long before the academic research community has finished their more painstaking efforts.

Molecular and physiological manifestations and measurement of aging in humans

In the 20th century, decreased mortality and lengthening of average human lifespan shifted the worldwide demographic structure toward the aged. This shift stemmed initially from treatment of infectious diseases and subsequently cardiovascular disorders. However, an increase in late-life disability has accompanied gains in healthy years lived (health span) and longevity. Biological aging is associated with a reduction in the regenerative potential in tissues and organs. Individuals with the same chronological age and their organs exhibit differential trajectories of age-related decline, and it follows that we should assess biological age distinctly from chronological age. Understanding the molecular and physiological phenomena that drive the complex and multifactorial processes underlying biological aging in humans will inform how researchers assess and investigate health and disease over the life course. In this review, we outline mechanisms of aging, discuss normal human aging at the organ-system level, suggest methods to measure biological age, and propose a framework to integrate molecular and physiological data into a composite score that measures biological aging in humans.

The heritable contribution to aging is limited for most humans, with genetics accounting for only 20-30% of lifespan variability in human twin and founder population family studies. However, heritable factors may represent a significantly larger contribution to lifespan at extreme ages, and the exceptionally aged may offer an opportunity to find rare genetic variants associated with longevity. Inter-related molecular and cellular phenomena occur during normal aging, intensify during accelerated or premature aging, and can be mitigated to increase lifespan. Researchers have proposed nine so-called 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 - that frame mechanisms underlying senescence. As we discuss in this section, many hallmarks suggest potential therapeutic targets to restore age-associated functional decline, although potential therapies are not completely benign. Translation of these hallmarks with surrogate measurements are important to include in a composite biological age score (BAS) because of their direct relationship with the molecular basis of aging.

Physiological aging involves a progressive detrimental change in maximal organ function with differential trajectories across organ systems. Importantly, multiple factors including genetics, environmental conditions, and developmental programming determine maximal organ function, which varies significantly between individuals. Aging affects all organ systems and must be assessed through a variety of physiological measures, as aging varies greatly organ-to-organ and person-to-person and results in impaired reserve capacity and limited ability to respond to stress. While there appears to be an organ-specific or organ-differential resilience and vulnerability of aging, frailty refers to the cumulative decline and increasing homeostatic imbalance that precedes the ultimate consequence of aging: death.

Chronological age offers limited information regarding the complex processes driving biological aging. Individuals with the same chronological age vary greatly in health and in disease and disability prompting the utility of defining a 'biological age'. The conceptualization of such a biological age distinct from chronological age has been proposed by many researchers with measures as crude as functional 'frailty' and as sophisticated as patterns of DNA methylation. While much research has focused on quantification of biological aging, a comprehensive and integrative score incorporating molecular biomarkers and physiological functional parameters is lacking. Current strategies to assess systemic biological age carry significant limitations as individual parameters to accurately reflect an individual's global loss of homeostasis have been elusive. Further, biological plausibility suggests that no single biomarker is likely to suffice given the underlying multisystem nature of the aging process with changes occurring on a molecular and organ-based level underscoring the utility of an aggregate score of biological aging. Scoring systems require careful integration of molecular markers (surrogates of the hallmarks of aging) with longitudinal physiological functional measures, yet little consensus exists regarding optimal methods for creation and evaluation of a composite biological age score (BAS).

We propose a conceptual framework for a composite BAS, which integrates available molecular measurements based on the hallmarks of aging and functional organ physiology measurements across the life course. Comprehensive and repeated assessments over time of existing and emerging molecular biomarkers and organ-specific functional measures in longitudinal epidemiologic cohorts in parallel with the use of sophisticated bioinformatics methodologies are needed to derive a global BAS. In general, components of the BAS should be i) highly correlated with chronological age, ii) predict organ-system and global age-related decline, and iii) be minimally invasive, readily observable, and reliably measured. Investigation into the optimal parameters used to derive a BAS will require collection and analysis of data sets that include successful agers without morbidity as well as accelerated agers with genetic progeroid syndromes, inflammatory pathologic conditions, and disease-related morbidity. Derivation and validation of a BAS will require multiple types of study designs including observational prospective population-based cohorts, leveraging large sample sizes with repeated measures over several decades as well as case-control studies and family-based studies to incorporate less common phenotypes of interest, including successful agers and accelerated agers with nongenetic and genetic conditions.

An Interview with James Peyer of Apollo Ventures

Apollo Ventures is one of the more recent additions to the presently small number of funds focused on investment in the longevity science space, and here I'll point out an interview with one of their founding partners. The Apollo principals are distinguished by being somewhat more vocal than most of their peers, the Methuselah Fund founders aside. To pick one example, the fund has launched the Geroscience online magazine to help advance the position that treating aging as a medical condition is both viable and desirable. As technologies based on the SENS view of achieving rejuvenation through damage repair arrive at the point of commercial viability, it is increasingly important that a healthy venture investment ecosystem exists to fund the biotech startups needed to push therapies towards the clinic.

Last week we talked with James Peyer, a partner at Apollo Ventures, to ask a few questions about how biotech is tackling the anti-aging space. For a long time, the anti-aging field has not seen much innovation, both due to a lack of scientific know-how as well as a lack of confidence on the part of pharma and regulatory agencies. Yet, in the past years, the field has started to turn into one of the most hyped areas in biotech, marked by the launch of companies like Unity Biotechnology, which recently raked in $116M in venture funding or Calico, which was co-founded by Google in 2013. Referring to a review article on the hallmarks of aging, Peyer explains that "within the last 5 years, our understanding has gone from theory and hypothesis-driven to really coalescing a strong data-driven knowledge base. The geroscience space has at least 80 mutations or chemicals that have been shown with some level of conviction to extend the healthy life span of a mouse."

Peyer mentions a group of scientists from Albert Einstein College of Medicine in New York that have been piloting such a preventative medicine study with a 7-year trial, to test whether the generic drug metformin can delay the onset of age-related conditions. "This model of a 7-year clinical trial though, that's not really something that can be easily translated to a commercial model with a patented drug. But what's going to come out of those trials in the next 5-10 years are biomarkers that will give us a hint on whether or not a drug is working to reduce the risk of age-related diseases, and then that biomarker could be used in future trials."

Apollo is following a slightly different path, though. The VC aims to go after geriatric syndromes, such as osteoarthritis, that are actually treatable medical conditions. "You'll be really focused on one indication that's a real clinical opportunity and move that towards the clinic just as you would with a traditional oncology drug or osteoarthritis drug. That's the opportunity that Apollo is really excited about and then, of course, there is the vision in the longer term that those two paths will come together and create a world where we can actually do preventive clinical trials. The big players that are now coming into the area are technology players like Jeff Bezos or Google. The internet space has attracted so much investment but the return profiles in this space actually look much worse compared to biopharma both in the US and the EU."

Link: http://labiotech.eu/labiotech-hangout-anti-aging-peyer/

Modifying Macrophages to Accelerate Healing

The immune cells called macrophages play an important role in the healing of injuries. Their activities appear to be the key to examples of exceptional regeneration in mammals, for example. This may have something to do with their clearance of the transient senescent cells generated during regeneration, or may be related to other signaling processes. Researchers have in previous years shown that adjusting the behavior of macrophages can alter the pace at which wounds heal, and it is hoped that this might be a compensatory approach capable of reducing the loss of regenerative capacity that occurs with aging. Here is a recent example of work that runs along the same lines:

It has long been known that macrophages play a key role in the normal wound healing process. These cells specialize in major cellular clean-up processes and are essential for tissue repair; they accelerate healing while maintaining a balance between inflammatory and anti-inflammatory reactions. "When a wound doesn't heal, it might be secondary to enhanced inflammation and not enough anti-inflammatory activity. We discovered that macrophage behaviour can be controlled so as to tip the balance toward cell repair by means of a special protein called Milk Fat Globule Epidermal Growth Factor-8, or MFG-E8."

The researchers showed that when there is a skin lesion, MFG-E8 calls for an anti-inflammatory and pro-reparatory reaction in the macrophages. Without this protein, the lesions heal much more slowly. Then the researchers developed a treatment by adoptive cell transfer in order to amplify the healing process. Adoptive cell transfer consists in treating the patient using his or her own cells, which are harvested, treated, then re-injected in order to exert their action on an organ. This immunotherapeutic strategy is usually used to treat various types of cancer. This is the first time it has been shown to also be useful in reprogramming cells to facilitate healing of the skin.

"We used stem cells derived from murine bone marrow to obtain macrophages, which we treated ex vivo with the MFG-E8 protein before re-injecting them into the mice, and we quickly noticed an acceleration of healing. The MFG-E8 protein, by acting directly upon macrophages, can generate cells that will orchestrate accelerated cutaneous healing. The beauty of this therapy is that the patient (in this case the mouse) is not exposed to the protein itself. If we were to inject the MFG-E8 protein directly into the body there could be effects, distant from the wound, upon all the cells that are sensitive to MFG-E8, which could lead to excess repair of the skin causing aberrant scars named keloids. The major advantage of this treatment is that we only administer reprogrammed cells, and we find that they are capable of creating the environment needed to accelerate scar formation."

Link: http://crchum.chumontreal.qc.ca/en/news-briefs/healing-wounds-cell-therapy

The Problem with Focusing on Healthspan

There are numerous ways to go about advocacy for the cause of treating aging as a medical condition, for the production of therapies to address the aging process. One might focus on talking about extended health, or the goal of greatly increased longevity, or the details of aging as a novel target for medicine, or discard aging as a topic in favor of the development of cures for common, well-recognized age-related diseases - something that can only be achieved through addressing the causes of aging, but many people are more receptive to treating age-related disease rather than treating aging, no matter that these must be one and the same in the end.

The advocates, researchers, and supporters in our small community are largely here because of the possibility of radical life extension and working rejuvenation therapies, especially those who were involved early on. The SENS rejuvenation research programs were initially supported because they are the most viable path forward towards the long-term goal of escaping the bounds of aging. SENS is the best of current plans for aging research because it aims to fundamentally change the human condition by bringing aging under control. Those who have over the years materially supported SENS to the greatest degree are also doing so precisely because the project aims high, not just because it is credible, but also because it isn't just another group of aging researchers talking about small changes to the aging process.

Once engaging with the broader community of larger, more conservative funding bodies, and scientific institutions, and high net worth individuals, however, these are near entirely people who either do not subscribe to transhumanist views of what is possible to achieve through medical science in our lifetimes, or who are not willing to be seen to adopt that minority viewpoint, or to espouse any viewpoint significantly different from those of their peers. Even when it is correct. Even when it is useful. Even when it is the only practical way forward to address aging and age-related disease. This is politics in all its prosaic ugliness. So as advocacy for the treatment of aging as a medical condition has spread over the years, the message has been watered down. We go from the goals of radical life extension and rejuvenation to a focus on modest increases in healthspan with no mention of longevity.

There is a faction in our core community that believes we should go along with this, and dial back our public positions. Talk about healthspan and only healthspan, because it will pull in more supporters and more conservative funding, those who are not comfortable with the topic of greatly extending longevity. Or at least we can point to aging research institutions much larger than the SENS community, who only talk about healthspan, and seem to do quite well on the funding front - the Buck Institute is a good example. Why can't we do that? If we did, the funds will still go to the same projects that are the foundation of rejuvenation therapies, stepping closer to an end to degenerative aging. Those projects will certainly do a good job of increasing healthspan: the only way to achieve radical life extension is to maintain youth, after all. Why care if goals are misaligned, if the funding sources think they are helping to achieve marginal, tiny gains in healthspan, because that is all they believe to be possible, and instead the result is large gains in both health and longevity?

I think that this argument misses the reality of what will happen in an environment where the rejuvenation research message is the same as that of people pushing supplements, trials of metformin, calorie restriction mimetics, boosted autophagy, cholesterol-lowering drugs, and so forth. When the greater conversation surrounding aging research is that it is a way to extend healthspan, and no-one talks about longevity, then the existing well-connected research groups that only work on slightly slowing aging will trample all over more radical groups like SENS researchers, by weight of numbers if nothing else. Those involved in research that aims to slightly slow aging can set a target of adding five years via some form of metabolic adjustment, and when it is achieved present the outcome as a great victory, task accomplished.

They will say that most people die by 90, with the unspoken assumption that this is set in stone. By adding five years of health, they can claim to have removed 20%-30% of the period of significant decline at the end of life, and isn't that amazing progress? Armed with this message of compression of morbidity, such marginal strategies will continue to dominate the research community, just as they do today. Those of us who see further and want the implementation of rejuvenation to significantly extend both health and life, not just a slight slowing of the aging process, will continue to struggle to move the field of aging research beyond paltry efforts. So much of what goes on in the field today is near meaningless, a waste of effort when considered against what is possible to achieve through rejuvenation: additional decades and then centuries and longer of health and vigor.

The problem is that this field of research already spends near all of its time on marginal, unambitious goals. The problem is that the vast majority of advocacy and public engagement is focused on painting tiny gains as large gains, via the vision of compression of morbidity that talks only of healthspan. When longevity is not open to improvement, small increases in healthspan can be made to look large. But it is an illusion. These increases are not large, vastly greater gains are possible, and this present state of affairs must change. Creating that change requires that we distinguish ourselves and our message. All of the progress to date in establishing SENS rejuvenation research as an important part of the field has been achieved by distinguishing ourselves, by talking about greatly increased health and longevity and an end to aging, rather than hiding that view simply because some people would rather not engage with it. Further progress requires that we persuade more people to the goal of radical life extension, not that we make ourselves look just like the many other groups whose research strategies cannot possibly do more than add a couple of years to health or life span.

If you are running with the one viable, best, most effective way forward, then the worst thing you can do is to make your efforts, your plan for the future, look like the initiatives undertaken by everyone else. The point is to upend the world, revolutionize the research community, drag the field kicking and screaming into this 21st century of endless potential in biotechnology, to defeat aging and all of the death and suffering it creates completely and comprehensively. Aim high. Do what the others are not doing. Bring the world to your point of view. You can't do that in camouflage, with the light under the bushel.

It Might be Possible to Prevent Cellular Senescence from Occurring at All

Cellular senescence is a cause of aging. Enormous numbers of cells become senescent day in and day out, entering a state in which they secrete damaging signals that disrupt surrounding tissue. Near all self-destruct or are quickly destroyed by the immune system. It is the very few that linger and build up in tissues over the years that act to produce chronic inflammation, fibrosis, and ultimately age-related disease. Current approaches to the problem aim at killing these errant cells, finishing the job that was left uncompleted by natural processes, and turning back this aspect of aging.

As this research makes apparent, it may be possible in the near term to take the alternative approach of completely preventing senescence from occurring in the first place. Is this a good idea, however? My first reaction would be to say "no, absolutely not"; senescent cells play a role in in wound healing, as well as in cancer suppression, at least in small numbers. Also, and perhaps more importantly, what happens to the enormous number of somatic cells that reach the end of their replicative life span if they don't then become senescent and self-destruct? How would this disrupt the normal balance of tissue regeneration and maintenance? But the researchers here are maintaining a genetically altered lineage of mice in which cGAS, a controlling gene for senescence, is deleted. So far the mice appear largely normal, though deficient in the innate immune response to cancer due to loss of other functions of cGAS. So perhaps this does bear further investigation from a therapeutic point of view despite all the obvious objections that might be mounted.

Since its formal description more than 50 years ago, cellular senescence has been extensively studied and found to play a critical role in cancer, aging, and age-related diseases. Cellular senescence can be induced by DNA damage, telomere shortening, oxidative stress, and oncogenes. Interestingly, all of these senescence-inducing conditions impinge on DNA directly or indirectly. The DNA damage response is a key event leading to senescence, which is characterized by the senescence-associated secretory phenotype (SASP) that includes expression of inflammatory cytokines. Here we show that cGMP-AMP (cGAMP) synthase (cGAS), a cytosolic DNA sensor that activates innate immunity, is essential for senescence. We found that damaged DNA is associated with cGAS in the cytoplasm and that deletion of cGAS abrogated SASP gene expression and other markers of cellular senescence. These results reveal cGAS as an important molecular link between DNA damage, SASP gene expression, and senescence.

Whereas cGAS clearly plays an important role in cellular senescence, it should be noted that cGas-deficient mice appear to be healthy. We have not observed a significant increase in spontaneous tumors in our cGas-/- mice even though some of these mice are more than 20 months old. Because there are multiple barriers for a cell to become a malignant cancer cell, removal of cGAS alone may not be sufficient to cause spontaneous tumors. However, it will be very interesting to test whether cGAS deletion promotes tumor development driven by oncogenes such as Ras, which is known to induce senescence. In this context, we recently reported that cGas-deficient mice are refractory to the antitumor effect of immune checkpoint blockade, indicating that cGAS is required for generating intrinsic antitumor immunity. It remains to be determined whether cGAS has a cell-autonomous function in impeding the transformation of a normal cell into a cancer cell.

Recent studies have provided strong evidence that senescence has a causal role in aging and age-related diseases and that genetic deletion of senescent cells increases the lifespan and ameliorates age-related pathologies in mice. It would be very interesting to determine whether cGAS plays a role in normal aging as well as age-related diseases in animal models. If so, cGAS inhibitors may be used for treating not only autoimmune diseases but also a variety of age-related diseases.

Link: https://dx.doi.org/10.1073/pnas.1705499114

Another Example of a Human Genetic Variant that Lowers Blood Lipids and thus Reduces Heart Disease Risk

In recent years researchers have discovered a couple of human gene variants that dramatically reduce blood lipid levels, in ANGPTL4 and ASGR1, which in turn reduces the risk of cardiovascular disease by slowing the development of atherosclerosis. The atherosclerotic lesions that form in blood vessel walls are seeded by oxidatively damaged blood lipids, and so lower lipid levels mean less seeding, all other things being equal. The research here presents another such gene variant, though by the sound of it one that has a lesser effect and isn't as widespread across populations.

A genetic variant that protects the heart against cardiovascular disease has been discovered in an isolated Greek population, who are known to live long and healthy lives despite having a diet rich in animal fat. In Mylopotamos in northern Crete the population are unusual as they have a diet that is rich in animal fat and should cause health complications, yet they have good health and live to an old age. In an attempt to solve the puzzle, scientists made a genetic portrait of the population by sequencing the entire genome of 250 individuals to get an in-depth view. This was the first time Mylopotamos villagers had their whole genome sequenced. The team then used the results to give a more detailed view of approximately 3,200 people for whom previous genetic information was known.

Scientists discovered a new genetic variant that was not previously known to have cardioprotective qualities. The variant, rs145556679, was associated with lower levels of both 'bad' natural fats - triglycerides - and 'bad' cholesterol - very low density lipoprotein cholesterol (VLDL). These factors lower the risk of cardiovascular disease. The cardioprotective variant may be almost unique to the Mylopotamos population. rs145556679 resides within an intron of the Down syndrome cell adhesion molecule like 1 (DSCAML1) gene, which is involved in cell adhesion in neuronal processes and is expressed in heart, liver, pancreas, skeletal muscle, kidney and brain. The genome sequencing results of a few thousand Europeans has only revealed one copy of this variant in a single individual in Tuscany, Italy. A separate variant in the same gene has also been found to be associated with lower levels of triglycerides in the Amish founder population in the United States.

Link: http://www.sanger.ac.uk/news/view/isolated-greek-villages-reveal-genetic-secrets-protect-against-heart-disease

Patterns of Aging in Both Normal and Longevity Mutant Nematodes

If you've been following efforts to slow aging in laboratory animals for any great length of time, then you should find the open access paper I'll point out today to be quite interesting - though note that the full text is PDF only at the time of writing. As a general rule, it is a lot harder to dissect the statistical shape of aging for a population than it is to just put numbers to mean and maximum life span. Measuring health to any useful level of detail is far more labor intensive than counting the study animals who are still alive. This means that there is actually comparatively little information on the numerous methods of slightly slowing aging when it comes to what exactly that means in various species: a longer span of health, a longer span of ill health, slower aging at the outset, slower aging at the end, the development of plateaus in which little aging takes place, and so forth.

For smaller and shorter-lived species such as nematodes, there is the potential to solve this problem with automation, however. In the past few years researchers have made considerable progress in automating lifespan and healthspan studies of nematodes, with one group constructing a Lifespan Machine that enables data mining of the health and longevity across tens of thousands of individuals. The authors of the paper quoted below have built what they call the WorMotel, serving a similar function. This new data is enabling a variety of novel insights.

What does this tell us about slowing aging? Judging from this latest set of results, it looks like yet another illustration to show that everything in the intersection of cellular metabolism and aging is more complex than we'd like it to be. More data is needed, and in gathering that data there continues to be some debate over the sort of outcome that is produced by any specific intervention: extended youth or extended decline. Do these interventions increase resistance to the consequences of damage, which seems the likely cause of an extended period of decline, or postpone damage, which seems the likely cause of extended youth? It would be very interesting to see what an analogous Lifespan Machine or WorMotel would find in flies, or in mice - though the cost would be prohibitive for mouse studies in the current model of automation.

For further consideration, bear in mind that slowing aging is itself a completely different mode of intervention from that of rejuvenation produced by repair of damage - the SENS approach. We don't yet have much to go on when it comes to how repair therapies differ in outcomes between species, or between individuals, or between approaches. Only one such class of therapy has any life span studies to reference, those for senescent cell clearance. Even there only a couple of studies exist and only a comparatively small number of animal subjects have undergone the therapies. There is every reason to expect that repair therapies will look very different from methods of slowing aging in the results produced, but we won't know the full details across populations and species for years yet, even for removal of senescent cells. Still, the sort of analysis in the paper below is exactly the sort of thing we'd like to see applied to rejuvenation therapies as they emerge from the laboratory.

Longitudinal imaging of Caenorhabditis elegans in a microfabricated device reveals variation in behavioral decline during aging

Here we describe the WorMotel, a microfabricated device for long-term cultivation and automated longitudinal imaging of large numbers of C. elegans confined to individual wells. Using the WorMotel, we find that short-lived and long-lived strains exhibit patterns of behavioral decline that do not temporally scale between individuals or populations, but rather resemble the shortest and longest lived individuals in a wild type population.

While many factors are known to modulate the mean lifespan of a population, less is known about how these factors alter the aging process on an individual level. It was recently shown that within a wild-type population, long-lived and short-lived animals differed in two ways. First, the rate of physiological decline was slower in long-lived individuals, as might be expected. The second, however, was counter-intuitive: the additional lifespan of longer-lived individuals was primarily due to differences toward the end of the lifespan. That is, long-lived animals exhibited longer periods of low physiological function, or 'extended twilight'. A different picture was suggested by a study using automated assays of lifespan in the 'Lifespan machine'. In this study it was reported that various genetic and environmental perturbations do not fundamentally change the shape of the survival curve, but rather only compress or dilate it in time. This result was interpreted as suggesting that the aging process in C. elegans is, at least at some point in its pathway, controlled by a single process describable by a single variable corresponding to the rate of aging.

We sought to determine to what extent, 'extended twilight' and/or scaling effects apply at the behavioral level in mutants with altered aging. The concept of a universal scaling parameter in aging would suggest that the short and long-lived individuals within any strain (whether with normal, short, or long mean lifespan) would resemble their short and long-lived counterparts in the reference strain, but with a temporal scaling. If the variations in aging rate among individuals in any isogenic strain are governed by similar factors, we would expect that long and short lived individuals would display similar late-life characteristics as their wild type counterparts. If, on the other hand, short-lived strains as a whole physiologically more closely resemble short-lived individuals of a wild type population, we might expect them to display late-life characteristics similar to these short lived individuals. Similarly, long-lived strains might display a range of late-life decays or alternatively collectively resemble long-lived worms in the reference strain.

Wild-type strain N2 worms exhibited an initial decline followed by a 'plateau' period of nearly constant spontaneous and stimulated activity and response duration and latency. When we compared the behavior of the shortest-lived and longest-lived quartile of N2 worms, we found that their behavioral declines were qualitatively different. The longest-lived animals exhibited a "decline and plateau" phenotype, in which an initial rapid decline in behavioral capacity is later replaced by a very gradual decline for the remainder of life. By contrast, the shortest-lived animals showed only the rapid decline in behavior before dying. The result that long-lived animals experience a long period of low behavior are consistent with the 'extended twlight' reported by other researchers.

Short-lived daf-16 mutants declined at a similar rate to N2, but did not exhibit any plateau phase; instead, daf-16 worms die after their initial behavioral decline. A similar effect was seen in daf-16 response duration and response latency, which do not level off but decrease or increase, respectively, at a similar rate until the time of death. Comparing the activity history of the shortest-lived N2 worms to that of daf-16 as a whole, we found a striking correspondence between the behavioral decline of the two groups. These results show that the behavioral decline of daf-16 animals is not a scaled version of the wild type distribution of decline, but instead resembles the short-lived individuals in a wild-type population.

Long-lived daf-2 mutants, in which behavioral quiescence has been previously reported, exhibited a decline in stimulated activity akin to that observed in N2 and daf-16 followed by a nearly constant low level of stimulated activity and response behaviors for the remainder of life. Spontaneous activity in daf-2, on the other hand, declined to near zero within 10 days of adulthood, where it remained until death. Long-lived strains age-1, tax-4, and unc-31 also exhibited the "decline and plateau" phenotype. These results show that aging behavior of daf-2 and other long-lived animals, like that of daf-16 animals, does not resemble a scaled version of wild type. Instead, they resemble the longest-lived individuals in a wild-type population, in that they exhibit a long plateau period of low locomotory function during late life.

These results suggest that the sources of variability in lifespan in individuals also impact functional decline in a corresponding manner. For example, the N2 worm that survives 15 days due to stochastic factors will decline in a similar manner to the daf-16 worm that survives 15 days. Furthemore, individuals with a 30-day lifespan will exhibit a different shape of functional decline, but this shape is dictated by the confluence of genetic and stochastic factors that result in the lifespan of 30 days.

Stem Cells versus Inflammation in Tendon Regeneration

Tendon tissue is one of many tissue types in mammals that is reluctant to heal completely following injury. Better methods of regeneration are desired, here as elsewhere in the body, and stem cell therapies show a great deal of promise in this regard. The most reliable of current stem cell therapy approaches, those with the greatest expectation of benefits to result for the patient, appear to work largely through a reduction in chronic inflammation. It is interesting to see that hold up in the case of tendons and their supporting stem cell populations.

New research suggests that tendon stem cells (TSCs) may be able to significantly improve tendon healing by regulating inflammation, which contributes to scar-like tendon healing and chronic matrix degradation. This has implications for the treatment of acute tendon injuries and chronic tendon disease. "Inflammation plays a critical role in acute and chronic tendon injuries and healing. Our findings represent an important foundation for the development of a new treatment that would regulate overwhelmed inflammation for tendon ruptures and tears, tendonitis, tendinopathy, and other tendon injuries and diseases."

In their study, the researchers used both in vitro human models and in vivo rat models. In vitro, isolated TSCs were stimulated with proinflammatory cytokines (proteins that can influence interactions between cells), and the expression of genes involved in inflammatory regulation was measured. In vivo, the researchers evaluated inflammatory responses by TSCs, including infiltration of macrophages (white blood cells that consume damaged or dead cells) and expression of anti-/proinflammatory cytokines, at different time points. Connective tissue growth factor (CTGF) was used in both models to stimulate the anti-inflammatory roles of TSCs. The researchers found that CTGF stimulation induced TSCs' production of anti-inflammatory cytokines, consequently leading to improved tendon healing and matrix remodeling. "Many would have predicted that tendon healing is inflammation-linked, but that the anti-inflammatory roles of TSCs could be so potent, and so amplifiable, is a striking finding."

Link: https://www.eurekalert.org/pub_releases/2017-05/foas-scm052317.php

Speculation on a Role for ATP in Age-Related Protein Aggregation

Researchers here suggest that ATP, the chemical energy store molecule produced by mitochondria, also serves to keep proteins soluble in the cell. This might help to explain the well known correlation between age-related mitochondrial dysfunction and age-related neurodegenerative diseases involving protein aggregates that build up in brain tissue. If mitochondria are producing less ATP, that may in turn accelerate the seeding of solid aggregates, and the consequent harm they produce. At this stage, the research is interesting but still fairly speculative when it comes to the degree to which this chemistry is relevant in disease states, however.

Adenosine triphosphate (ATP) performs many jobs in a cell. It carries energy, serves as a signaling molecule, and is the source of adenosine in DNA and RNA. But cells contain far more ATP than these known uses seem to require. That might be because ATP also can solubilize proteins, suggests a new study.

ATP has the general characteristics of a hydrotrope, an amphiphilic molecule that has both a hydrophilic and a hydrophobic component but does not assemble into structures such as micelles. Hydrotropes are used industrially to solubilize hydrophobic species in aqueous solution. The hydrophobic portion of hydrotropes - such as ATP's adenosine - likely interacts with the hydrophobic species, while the hydrophilic part - such as ATP's triphosphate - allows the species to stay in solution.

In the new work, a team investigated the effects of ATP on the aggregation of several proteins. They found that ATP could prevent the aggregation of two proteins known to form amyloid clumps. For a third protein, ATP was further able to dissolve fibers of already aggregated protein. And ATP kept proteins in boiled egg white from aggregating. "Most healthy cell functions require that proteins remain soluble at enormous intracellular concentrations, without aggregating into pathogenic deposits. The cell may exploit a natural hydrotrope to keep itself in a functioning, dynamic state."

Link: http://cen.acs.org/articles/95/i21/New-role-cells-suggested-ATP.html

In Essence, All Aging Research Revolves around the Science and Advocacy of SENS, the Strategies for Engineered Negligible Senescence

Today's popular science article for consideration is the usual mix of frustrating and interesting remarks that result when various researchers are convinced to talk to the press on the subject of SENS rejuvenation research. I in no way exaggerate when I say that all approaches to the research of aging, all of the intent in aging research, all of the fundamental disagreements in the field, ultimately revolve around SENS, the Strategies for Engineered Negligible Senescence. The advocacy and the science of SENS are the moral and technological sun in this solar system, for all that many of those orbiting it apparently would rather things were otherwise. Is the point of aging research to cure aging, rejuvenate the old, and greatly extend healthy human life spans? Is the point of aging research to move as rapidly as possible to this goal? In the SENS view, yes, and with specific plans for how the medical control of aging can be realized. Everyone else in the field must be defined by their answers to these questions, and thus by their position on SENS, their differences from the SENS view.

When looking in on this situation from the outside, it is important to realize that (a) more than fifteen years after its introduction, SENS research still represents only a tiny fraction of the research field, (b) that its origins are as an outsider group, its founders entering the research community because they were sufficiently outraged by its lack of action with regard to aging to put aside their own plans, and (c) that only SENS and SENS-like research appears to be producing the basis for cost-effective interventions to address aging as a medical condition. Given this situation, no-one in the field can really ignore SENS, but there are nonetheless a great many who would prefer to.

In one sense, the SENS approach to aging, considering it as the downstream consequence of fundamental damage that should be repaired, has already won the war of ideas: establishment research groups have taken up their own SENS-like agendas based on identifying damage and addressing it in order to turn back aspects of aging. Researchers now argue over how to effectively treat aging rather than remaining silent. Senescent cell clearance, on the SENS list for more than fifteen years on this basis of many lines of research from the past few decades, has in recent years been proven to be a reliable means of reversing numerous aspects of aging in animal studies. It is well on the way to the clinic, under development by a number of funded startup companies. This significant progress has required a fraction of the expenditure to date on, say, calorie restriction mimetic drugs or other ways to slightly slow aging that are diametrically opposed to the SENS philosophy. These are approaches that do not repair root cause damage, but rather try to alter metabolism to slow down accumulation of damage. Senescent cell clearance therapies to date demonstrate very well the point that SENS approaches are cheaper and better, as we should expect of any attempt to repair damage rather than just slow it down.

Yet in another sense, SENS has barely touched on the bigger picture of research and development. It is a tiny fraction of the ongoing work in the field. The vast majority of aging research remains investigative only, with no intention of producing therapies. Only a couple of the characteristically SENS approaches have made it into the mainstream in a big way, senescent cells and amyloid clearance. The first working, real rejuvenation therapies are not yet available in the nearest clinic. Yet tiny fraction as it is, it is the fraction that matters when it comes to results, as the past few years of work on senescent cell clearance has demonstrated. When the only thing that really matters is results, given that the successful treatment of aging is a matter of life and death for all of us, that puts SENS firmly at the center of the field.

SENS as a line of advocacy and set of specific research programs to achieve rejuvenation has helped to fundamentally change the research community since the turn of the century, from one in which no-one could talk about treating aging as a medical condition, to one in which young researchers publish openly on this topic and the first therapies are moving towards the clinic. Yet the researchers whose field has been changed remain on the whole remarkably unwilling to credit any of this to the small community of advocates and researchers who have occupied the central point of strategy and intent in their field. Even those researchers who ten years ago penned a letter dismissing all of SENS as something other than science, the presented evidence for the merits of senescence cell clearance included, find it hard today to admit outright that they were completely wrong. But everything of importance in aging research comes back down to SENS in the end: are research groups working on meaningful ways to turn back aging, or are they just wasting time and funding? What matters more than saving all of the lives lost to degenerative aging? Than preventing all of the suffering caused by degenerative aging? This is a meaningful question in a field that is still in the ragged process of a slow - and apparently sometimes reluctant - change from pure research to applied research, and whose members often seem quite hostile to the SENS advocates who ask these and other pointed questions.

Can Human Mortality Really Be Hacked?

It's just after 10:30 a.m. on a pleasant weekday morning at the SENS Research Foundation, a biotech lab in Mountain View, California. I've come to speak to its chief science officer, Aubrey de Grey. The 54-year-old's long hair, tied back in a ponytail, is turning gray, a change that would be unremarkable if he weren't one of the world's most outspoken proponents of the idea that aging can be completely eradicated. Unlike most scientists, he isn't shy about making bold speculations. He believes, for example, that the first person who will live to be 1,000 years old has most likely already been born. In 2009, de Grey founded the nonprofit SENS Research Foundation, the world's first organization dedicated to "curing" human aging, not just age-related diseases. The organization, which conducts its own research and funds studies by other scientists, occupies an unassuming space in a small industrial park. Its walls are affixed with large, colorful posters illustrating human anatomy and the inner workings of cells.

The basic vision behind SENS is that aging isn't an inevitable process by which your body just happens to wear out over time. Rather, it's the result of specific biological mechanisms that damage molecules or cells. Some elements of this idea date back to 1972, when the biogerontologist Denham Harman noted that free radicals cause chemical reactions, and that these reactions can damage the mitochondria, the powerhouses within cells. De Grey takes this concept further than most scientists are willing to go. His 1999 book argued that there could be a way to obviate mitochondrial damage, slowing the process of aging itself. Now SENS is working to prove this. Its scientists are also studying other potential aging culprits, such as the cross-links that form between proteins and cause problems like arteriosclerosis, and senescent cells that stop dividing but accumulate inside us, secreting proteins that contribute to inflammation. They're looking at damage to chromosomal DNA, and at "junk" materials that accumulate inside and outside cells (such as the plaques found in the brains of Alzheimer's patients). As de Grey's thinking goes, if we could figure out how to remove senescent cells and other damage using approaches like drugs or gene therapy, along with other types of repair, we could potentially keep our bodies vital forever.

This desire to eradicate aging has, in the last decade, inspired a mini-boom of private investment in Silicon Valley, where a handful of labs have sprung up in SENS' shadow, funded most notably by tech magnates. It's this influx of wealth that has brought novel anti-aging theories out of the scientific fringes and into gleaming Silicon Valley labs. De Grey notes that developing the means to make everyone live forever is not cheap. Further, immortality, it turns out, is not such an easy sell: Most people don't like the idea of living forever. "I find it frustrating that people are so fixated on the longevity side effects," de Grey says, clearly irritated. "And they're constantly thinking about how society would change in the context of everyone being 1,000 years old or whatever. The single thing that makes people's lives most miserable is chronic disease, staying sick and being sick. And I'm about alleviating suffering."

Judy Campisi works in Novato at the Buck Institute for Research on Aging, a gleaming profit research institution. "For 99.9 percent of our human history as a species, there was no aging," she says. Humans were very likely to die by our 30s from predation, starvation, disease, childbirth or any number of violent events. Life spans in the developed world have more than doubled over the past century or so, but this hasn't happened through any interventions against aging itself. Rather, it's a byproduct of innovations such as clean water, medication, vaccinations, surgery, dentistry, sanitation, shelter, a regular food supply and methods of defending against predators. A biochemist and professor of biogerontology, Campisi has spent her career studying aging and cancer, and the role senescent cells play in both. She has researched these cells in her lab and published widely on the possible evolutionary reasons they remain in our bodies. She posits that for most of human history, natural selection didn't favor living to old age. Evolution protected younger people so they could pass along their genes, and senescent cells play a very important role.

"One thing evolution had to select for was protection from cancer," she says. "Because we are complex organisms, we have lots of cells in our body that divide, and cell division is a very risky time for a cell because it's easy to pick up a mutation when you are replicating three billion base pairs of DNA." If a cell doesn't divide, there are fewer chances for such a mutation to creep in. "So evolution put into place these very powerful tumor suppressant mechanisms - senescent cells - but they only had to last for 40 years at the most." Senescent cells contribute to inflammation, and "inflammation is the number one risk factor for all diseases of aging, including cancer." The idea that senescent cells contribute to aging was first postulated in the 1960s. Yet 50 years later, scientists still don't entirely understand the role they play. All Campisi can say definitively is that, for most of human history, there was "no evolutionary pressure to make that system better because everybody died young."

When I ask Campisi why some scientists talk about "curing" aging, she says it comes down to getting interventions approved. "There are people who want to consider aging a disease for the purposes of going to regulatory agencies and having a specific drug able to treat a specific symptom, which you can only do if it's recognized as a disease." But Campisi stresses that living forever is not the goal of most research on aging. Instead, she says it's primarily aimed not at life span but "health span" - increasing the number of years that people can remain physically and mentally agile. Campisi has known de Grey for years, collaborates with SENS and even serves on the organization's advisory board. I ask what she makes of his assertion that someone alive today will reach the age of 1,000. "I have to tell you Aubrey has two hats," she says, smiling. "One he wears for the public when he's raising funds. The other hat is when he talks to a scientist like me, where he doesn't really believe that anyone will live to 1,000 years old. No."

In 2006, the magazine MIT Technology Review published a paper called "Life Extension Pseudoscience and the SENS Plan." The nine co-authors, all senior gerontologists, took stern issue with de Grey's position. "He's brilliant, but he had no experience in aging research," says Heidi Tissenbaum, one of the paper's signatories and a professor of molecular, cell and cancer biology at the University of Massachusetts Medical School. "We were alarmed, since he claimed to know how to prevent aging based on ideas, not on rigorous scientific experimental results."

More than a decade later, Tissenbaum now sees SENS in a more positive light. "Kudos to Aubrey," she says diplomatically. "The more people talking about aging research, the better. I give him a lot of credit for bringing attention and money to the field. When we wrote that paper, it was just him and his ideas, no research, nothing. But now they are doing a lot of basic, fundamental research, like any other lab." In marked contrast with de Grey, however, Tissenbaum doesn't see aging itself as the problem. "I don't think it's a disease," she says. "I think it's a natural process. Life and death are a part of the same coin." Meanwhile, scientists are trying to understand why the brain deteriorates over time, losing mass and neural circuitry. Tissenbaum and others are trying to understand these mechanisms, hoping to find new treatments for neurodegenerative diseases. But she doesn't expect any intervention to keep humans healthy forever. "It may be that the brain has a finite life span," she says.

Assessing the Prevalence of Sarcopenia

Sarcopenia is the name given to the characteristic loss of muscle mass and strength that accompanies aging, though formal definitions under development tend towards including only those with the greatest degree of loss. This is something of a political problem in the research and medical community; the tendency to describe some level of aging as normal and therefore not treatable, while classifying greater degrees of exactly the same process and symptoms as a disease. Along with the failure of the immune system and loss of bone strength, sarcopenia is one of the most evident forms of age-related frailty. A good many research groups are involved in the attempt to find ways to slow or reverse this decline, most of which are focused on mechanisms of stem cell activity and tissue regeneration rather than fundamental damage after the SENS model of aging. Of the present options outside the SENS portfolio, gene therapies or antibody therapies that target the muscle growth regulators of myostatin and follistatin appear most promising in the short term, given the rapid progress taking place in the broader field of genetic editing.

Sarcopenia, an age-related decline in muscle mass and function, is one of the most important health problems in elderly with a high rate of adverse outcomes. However, several studies have investigated the prevalence of sarcopenia in the world, the results have been inconsistent. The current systematic review and meta- analysis study was conducted to estimate the overall prevalence of sarcopenia in both genders in different regions of the world.

Electronic databases were searched between January 2009 and December 2016. The population- based studies that reported the prevalence of sarcopenia in healthy adults aged ≥ 60 years using the European Working Group on Sarcopenia in Older People (EWGSOP), the International Working Group on Sarcopenia (IWGS) and Asian Working Group for Sarcopenia (AWGS) definitions, were selected. According to these consensual definitions, sarcopenia was defined by presence of low muscle mass (adjusted appendicular muscle mass for height) and muscle strength (handgrip strength) or physical performance (the usual gait speed). The random effect model was used for estimation the prevalence of sarcopenia.

Thirty-five articles met our inclusion criteria, with a total of 58,404 individuals. The overall estimates of prevalence was 10% in men and 10% in women, respectively. The prevalence was higher among non-Asian than Asian individuals in both genders especially, when the Bio-electrical Impedance Analysis (BIA) was used to measure muscle mass (19% vs 10% in men; 20% vs 11% in women). Despite the differences encountered between the studies, regarding diagnostic tools used to measure of muscle mass and different regions of the world for estimating parameters of sarcopenia, present systematic review revealed that a substantial proportion of the old people has sarcopenia, even in healthy populations. However, despite sarcopenia being a consequence of the aging progress, early diagnosis can prevent some adverse outcomes.

Link: https://dx.doi.org/10.1186/s40200-017-0302-x

A View of How Senescent Cells Disrupt Tissue Regeneration

Normal tissue regeneration is disrupted in various ways in later life, such as the tendency for increased fibrosis, scar tissue formation rather than normal regrowth. Researchers here theorize on the role of growing numbers of lingering senescent cells in this age-related loss of function, a complex situation because the transient creation of senescent cells, soon destroyed, is an important part of the normal wound healing process. Despite their positive function in that scenario, the accumulation of long-lasting senescent cells is nonetheless one of the root causes of aging. These cells produce a harmful effect on surrounding tissue through the potent mix of signals they generate, known as the senescence-associated secretory phenotype (SASP), which drives chronic inflammation, among other items.

The inability of adult tissues to transitorily generate cells with functional stem cell-like properties is a major obstacle to tissue self-repair. Nuclear reprogramming-like phenomena that induce a transient acquisition of epigenetic plasticity and phenotype malleability may constitute a reparative route through which human tissues respond to injury, stress, and disease. However, tissue rejuvenation should involve not only the transient epigenetic reprogramming of differentiated cells, but also the committed re-acquisition of the original or alternative committed cell fate. Chronic or unrestrained epigenetic plasticity would drive aging phenotypes by impairing the repair or the replacement of damaged cells; such uncontrolled phenomena of in vivo reprogramming might also generate cancer-like cellular states. We herein propose that the ability of senescence-associated inflammatory signaling to regulate in vivo reprogramming cycles of tissue repair outlines a threshold model of aging and cancer.

The degree of senescence/inflammation-associated deviation from the homeostatic state may delineate a type of thresholding algorithm distinguishing beneficial from deleterious effects of in vivo reprogramming. First, transient activation of NF-κB-related innate immunity and senescence-associated inflammatory components (e.g., IL-6) might facilitate reparative cellular reprogramming in response to acute inflammatory events. Second, para-inflammation switches might promote long-lasting but reversible refractoriness to reparative cellular reprogramming. Third, chronic senescence-associated inflammatory signaling might lock cells in highly plastic epigenetic states disabled for reparative differentiation. The consideration of a cellular reprogramming-centered view of epigenetic plasticity as a fundamental element of a tissue's capacity to undergo successful repair, aging degeneration or malignant transformation should provide challenging stochastic insights into the current deterministic genetic paradigm for most chronic diseases, thereby increasing the spectrum of therapeutic approaches for physiological aging and cancer.

If the loss of differentiation features following reprogramming is not accompanied by re-acquisition of the original or alternative differentiated cell fate, the resulting tissue plasticity might impair the repair or replacement of damaged cells. The ability of SASP-associated pro-inflammatory cytokines to regulate stemness and nuclear reprogramming raises the notion that a SASP-impaired local environment could interfere with tissue rejuvenation by imposing the so-called "stem-lock" state. Chronic inflammatory conditions via exposure to IL-1, which normally functions as a key "emergency" signal and a master regulator of SASP by inducing downstream effectors such as IL-6, has been shown to impair tissue homeostasis and to induce an aged appearance of the hematopoietic system by restricting stem cell differentiation.

While counterintuitive, given the ability of SASP factors including IL-6 to transiently create a permissive environment for in vivo reprogramming capable of inducing cellular plasticity and tissue regeneration, a prolonged promotion of such progenerative response might reduce tissue rejuvenation and promote aging by self-enhancing futile cycles of SASP/IL-6-driven reparative cellular reprogramming. Compared with young tissues containing few senescent cells where transient creation of senescent cells might cause temporary reprogramming and differentiation/proliferation to replenish cells, the prolonged accumulation of senescent cells in tissues that are old or under high levels of stress (e.g., following medical procedures such as chemotherapy) might be accompanied by a defective clearance of damaged, senescent cells, which can promote further SASP accumulation. A situation of chronic SASP secretion might not only counter the continued regenerative stimuli by promoting cell-intrinsic senescence arrest in single damaged cells but also paradoxically impose a permanent, locked gain of stem cell-like cellular states with blocked differentiation capabilities in surrounding cells.

Link: https://doi.org/10.3389/fcell.2017.00049

Are there Commonalities Between Neurodegenerative Conditions that can be Targeted to Produce General Therapies?

Cancer research will only progress meaningfully towards control of all cancer when the research community puts significant time and effort into finding common mechanisms shared by many or all cancers - or better still, attacking the one known mechanism shared by all cancers, which is abuse of telomere lengthening. The reason that the cancer community struggles with progress is that there are hundreds of forms of cancer, and researchers largely continue to try to address them one by one. There is a lot of cancer, but only so much funding and only so many scientists. A better way forward is needed. The question for today, however, is whether or not this principle of action extends to another broad class of widely varied conditions, the neurodegenerative diseases that corrode the aging brain. Are there faster paths forward here as well, built on common mechanisms? I'm on the fence on this topic. I think it easy to argue that any two different forms of neurodegeneration are far more distinct from one another than any two types of cancer; they involve completely different ways to disrupt cellular activity in the brain or kill brain cells. There is no one mechanism with a clear analogy to the central role of abuse of telomere lengthening in cancer when it comes to neurodegenerative disease.

Still, it is tempting to speculate on mechanisms that might be shared between many different types of neurodegenerative disease, because if they do exist, that offers the same prospect of faster progress, if only the research community better directed its efforts. Obviously, at root, many layers of cause and consequence removed from the disease state, we can look to the forms of tissue and cell damage outlined in the SENS rejuvenation research proposals - the root causes of aging. Most neurodegeration is age-related because it is caused by aging, and thus the first resort should probably be attempts at first principles rejuvenation, therapies based on repair of root cause damage. Sadly, few in the research community agree with that statement; persuading them to see the light is an ongoing project. Further along the chain of damage and dysfunction can be found other examples. We might, for example, consider the failure of cerebral spinal fluid drainage channels as a possible common factor in all conditions involving the build-up of aggregates and other unwanted molecular waste in the brain. Equally, there may be other, more esoteric points at which intervention is possible, though in general the later in the disease process the intervention occurs, the less likely it is to produce more than marginal benefits, if the past century of medicine is any guide to what the future holds. You might look at this work as an example of the type:

Alzheimer's, Parkinson's, and Huntington's diseases share common crucial feature

Abnormal proteins found in Alzheimer's disease, Parkinson's disease, and Huntington's disease all share a similar ability to cause damage when they invade brain cells. The finding potentially could explain the mechanism by which Alzheimer's, Parkinson's, Huntington's, and other neurodegenerative diseases spread within the brain and disrupt normal brain functions. The finding also suggests that an effective treatment for one neurodegenerative disease might work for other neurodegenerative diseases as well. "A possible therapy would involve boosting a brain cell's ability to degrade a clump of proteins and damaged vesicles. If we could do this in one disease, it's a good bet the therapy would be effective in the other two diseases."

Previous research has suggested that in all three diseases, proteins that are folded abnormally form clumps inside brain cells. These clumps spread from cell to cell, eventually leading to cell deaths. Different proteins are implicated in each disease: tau in Alzheimer's, alpha-synuclein in Parkinson's and huntingtin in Huntington's disease. The new study focused on how these misfolded protein clumps invade a healthy brain cell. The authors observed that once proteins get inside the cell, they enter vesicles (small compartments that are encased in membranes). The proteins damage or rupture the vesicle membranes, allowing the proteins to then invade the cytoplasm and cause additional dysfunction. When protein clumps invade vesicles the cell gathers the ruptured vesicles and protein clumps together so the vesicles and proteins can be destroyed. However, the proteins are resistant to degradation. "The cell's attempt to degrade the proteins is somewhat like a stomach trying to digest a clump of nails."

Endocytic vesicle rupture is a conserved mechanism of cellular invasion by amyloid proteins

Numerous pathological amyloid proteins spread from cell to cell during neurodegenerative disease, facilitating the propagation of cellular pathology and disease progression. Understanding the mechanism by which disease-associated amyloid protein assemblies enter target cells and induce cellular dysfunction is, therefore, key to understanding the progressive nature of such neurodegenerative diseases. In this study, we utilized an imaging-based assay to monitor the ability of disease-associated amyloid assemblies to rupture intracellular vesicles following endocytosis. We observe that the ability to induce vesicle rupture is a common feature of α-synuclein (α-syn) assemblies, as assemblies derived from wild type (WT) or familial disease-associated mutant α-syn all exhibited the ability to induce vesicle rupture. Similarly, different conformational strains of WT α-syn assemblies, but not monomeric or oligomeric forms, efficiently induced vesicle rupture following endocytosis.

The ability to induce vesicle rupture was not specific to α-syn, as amyloid assemblies of tau and huntingtin Exon1 with pathologic polyglutamine repeats also exhibited the ability to induce vesicle rupture. We also observe that vesicles ruptured by α-syn are positive for the autophagic marker LC3 and can accumulate and fuse into large, intracellular structures resembling Lewy bodies in vitro. Finally, we show that the same markers of vesicle rupture surround Lewy bodies in brain sections from PD patients. These data underscore the importance of this conserved endocytic vesicle rupture event as a damaging mechanism of cellular invasion by amyloid assemblies of multiple neurodegenerative disease-associated proteins, and suggest that proteinaceous inclusions such as Lewy bodies form as a consequence of continued fusion of autophagic vesicles in cells unable to degrade ruptured vesicles and their amyloid contents.

Complicating the Bigger Picture of Protein Aggregation in Aging

A number of different proteins can misfold or otherwise be altered in ways that cause them to precipitate into solid deposits. The best known of these are best known because they are are a contributing cause of age-related disease, through their disruption of normal tissue function or via a surrounding halo of biochemistry that is in some way toxic to cells. There are twenty or so forms of amyloid deposits, for example, and of these the most attention is given to the amyloid-β involved in Alzheimer's disease - though transthyretin amyloid is catching up, given the growing evidence for its role in heart failure. In the paper here, the authors suggest that the way in which amyloids and other similar deposits get started involves interactions between the aggregation of potentially many other proteins: in other words that proteins A and B might aggregate without any great evidence for a link to resulting harm, but their aggregation acts to seed the aggregation of protein C that is very definitely harmful to health over the years.

A variety of neurodegenerative diseases are associated with the misfolding and aggregation of specific proteins. In Alzheimer's disease (AD), amyloid-β (Aβ) peptides and tau proteins aggregate and ultimately form the characteristic pathological hallmarks: amyloid plaques and neurofibrillary tangles (NTFs) respectively. In recent years, understanding the initiation and spread of these hallmark protein aggregates has become a central area of investigation. The current model stipulates that aggregation in disease is initiated by a protein seed that forms a template for further protein aggregation. Support for this model comes from research showing that the exogenous addition of minute amounts of Aβ or tau seeds greatly accelerates the onset of aggregation both in vitro and in vivo. An important and currently understudied question is how aging influences protein aggregation in neurodegeneration. Recently, physiological protein insolubility in the context of aging has become a hot topic of research. Indeed, numerous publications demonstrate that protein aggregation is not restricted to disease but a normal consequence and possibly cause of aging.

Until now, it remains unclear whether and how age-dependent protein aggregation and disease-associated protein aggregation influence each other. One possibility is that age-dependent aggregates indirectly accelerate disease-associated protein aggregation by stressing the cell and/or titrating away anti-aggregation factors. Another possibility is a direct interaction whereby disease-associated proteins and age-dependent aggregation-prone proteins co-aggregate. In support of this latter hypothesis, proteins prone to aggregate during normal aging are significantly overrepresented as minor protein components in amyloid plaques and NFTs. Recent research reveals that the sequestration of these age-dependent aggregation-prone proteins in the disease aggregates is a source of toxicity. However, whether misfolded proteins aggregating with age can form heterologous seeds that initiate Aβ aggregation has not been investigated.

Although current research focuses on homologous seeding, there are a few examples of cross-seeding (or heterologous seeding) mostly between different disease-aggregating proteins. For instance, Aβ is a potent seed for the aggregation of human islet amyloid polypeptide (hIAPP) involved in type II diabetes; Aβ and prion protein PrPSc cross-seed each other and accelerate neuropathology; and both α-synuclein and Aβ co-aggregate with tau and enhance tau pathology in vivo. Finally, we recently showed that cross-seeding between different age-dependent aggregating proteins is possible in the absence of disease. Here, we demonstrate that cross-seeding during aging is likely to be an important mechanism underlying protein aggregation in AD.

We show for the first time that highly insoluble proteins from aged Caenorhabditis elegans or aged mouse brains, but not from young individuals, can initiate amyloid-β aggregation in vitro. We tested the seeding potential at four different ages across the adult lifespan of C. elegans. Significantly, protein aggregates formed during the early stages of aging did not act as seeds for amyloid-β aggregation. Instead, we found that changes in protein aggregation occurring during middle-age initiated amyloid-β aggregation. Mass spectrometry analysis revealed several late-aggregating proteins that were previously identified as minor components of amyloid-β plaques and neurofibrillary tangles such as 14-3-3, Ubiquitin-like modifier-activating enzyme 1 and Lamin A/C, highlighting these as strong candidates for cross-seeding. Overall, we demonstrate that widespread protein misfolding and aggregation with age could be critical for the initiation of pathogenesis, and thus should be targeted by therapeutic strategies to alleviate neurodegenerative diseases.

Link: https://doi.org/10.3389/fnagi.2017.00138

Why is the Postfertile Longevity Exhibited by Humans so Unusual?

Humans are an unusually long-lived species when compared to other mammals of a similar size, and even in comparison to our near relative primates. Further, we exhibit an extended period of life following loss of fertility, a rare form of life history that is only observed in a few other species. The grandmother hypothesis is one of the possible explanations for the evolution of extended longevity without fertility; it is a selection effect based on the ability of older individuals to assist in the survival of their descendants. Given the existence of such a mechanism, however, why is it not more widespread?

Data on historical agricultural populations and modern hunter-gatherers show that these groups enjoy significant postfertile periods. Taking an evolutionary approach, the Grandmother Hypothesis proposes that this reproductive inactivity is in fact adaptive. With the sacrifice of continued reproduction, an individual may increase their inclusive fitness by decreasing the interbirth intervals of their offspring. The care that would otherwise be put into one's own children can now be put into weaned (and increasingly independent) grandchildren, allowing their own offspring to reproduce again sooner. Otherwise put, the cost of a reduced relatedness coefficient may be outweighed by an increase in total number of grandchildren resulting from the diverted care.

A valid objection to the Grandmother Hypothesis, however, is if grandmothering can result in a higher fitness, why are significant postfertile life stages so rare? Among vertebrates in the wild, only humans, Globicephala macrorhynchus (pilot whales) and Orcinus orca (resident killer whales), have a significant proportion of individuals with such a life history. In this study, we present a model to investigate this objection. Our model assumes only that individuals transition through various life stages and that there is an average time to conception and gestation. In one of those stages, individuals have the option to provide care for a certain number of their grandchildren thereby allowing their own offspring to reproduce again sooner.

By comparing inclusive fitnesses of individuals that provide intergenerational care with those that instead continue to reproduce into old age, we arrive at a necessary condition for grandmothering to be an evolutionarily stable strategy (ESS). This condition, or stability threshold, relates the number of grandchildren that care must be given to with the ratio of the length of the first two life stages. It tells us nothing about when or how grandmothering may arise initially in a population, but places restrictions on when it will persist. We then make the observation that if a grandmother is to provide care for even one set of grandchildren, their expected postfertile stage must be sufficiently long. More precisely, for grandmothering to be adaptive, it must be the case that postfertile life exceeds the time taken to raise a weaned child to independence. If this were not the case, grandmothers would not be able to shorten their offspring's time between births by caring for some infants themselves. In this way, we derive an eligibility threshold that tells us when grandmothering is a strategy with any possible evolutionary advantage. These eligibility and stability criteria must both be satisfied for grandmothering to evolve and then, most importantly for our purposes, to persist.

Our analyses show that there is conflict between the stability and eligibility thresholds. As it becomes increasingly easier to meet one of them, it becomes increasingly harder to fulfill the other and vice versa. This conflict is, at its core, a grandparent-grandoffspring conflict analogous to parent-offspring conflicts. The result of this is that there is a narrow range over which we should expect grandmothering to evolve and then to persist. In other words, we should in fact expect grandmothering to be rare.

Link: https://dx.doi.org/10.1002/ece3.2958

Planning a Single Person Trial of Senolytic Drug Candidates

This post should be considered as part of an ongoing and yet to be concluded process of thinking out loud on the topic of self-experimentation with senolytic drug candidates. These are compounds that to some degree selectively destroy senescent cells in animal studies. Some have been shown to have positive effects in animal studies of various sorts in the years prior to the present wave of interest in senescent cell clearance, and some of those effects might be plausibly linked to removal of senescent cells. Some were tested as cancer therapeutics, or analgesics, or for other uses. Some have serious and harmful side effects, as is the case for most prospective chemotherapeutics. They are intended to destroy cells, and they are nowhere near as discriminating as we'd all like them to be. Nonetheless, all of these drug candidates are to varying degrees available for purchase, and thus available for self-experimentation.

Now, self-experimentation has a long and storied history in the scientific community. Many noted researchers at some point obtained the first human data from their own bodies, and that seems to me the most ethical of approaches: the researcher assumes the risks. Setting aside for a moment the question of risk, the point to take away from this history is that there is absolutely no point in doing this unless you measure and publish what you did and what happened. Guessing at outcomes or using drug candidates merely in the hope that effects will carry over from studies in mice helps no-one. The same goes for picking easily measured outcomes just because they are easy to measure. The objective here is to learn something and transmit that learning, which is possible even in an environment of single person tests without controls, provided we are seeking effects that are both large and reliable, and provided we go about this is a sensible manner. In this context, self-experimentation can help to point the way for those with the resources to run more rigorous experiments capable of better quantifying effect size, optimal dosage, and the like.

Obtain a Cooperative Physician

The first step is to ensure that you have a physician who understands what you are intending to do and achieve, and is willing to order up the required tests. You will need an interface and guide to the local medical establishment, especially for the more expensive scanning and testing. This usually isn't all that hard to obtain, since you'll be paying.

Obtain a Cooperative Laboratory Company

You will need a company to act as an interface with suppliers, as many of them will not accept orders for senolytics from individuals. In this age of drug prohibition, it also smooths the way for biochemical deliveries across national borders for them to be between laboratory companies. You will also need a company with laboratory resources, or that can act as an interface to laboratory services for some of the work you might want carried out. The ideal situation here is to work with someone within the community, via your connections, as it would otherwise require some legwork to find a company willing to work with you.

Determine the Health Metrics to be Assessed

The ideal set of data desired at the end of a short test of senolytics includes (a) the degree to which senescent cells were removed, and (b) the degree to which relevant measures of aging were reversed. The reality is that both require some compromises given the current state of medical testing. After some reading around and thinking on what would likely be affected by cellular senescence, given what is presently known, I settled on the following tests for consideration. One important item is that the normal values obtained from healthy individuals for a given test must vary to a large enough degree across the age range of 30 to 60 to make it useful to run the test if you are something other than very old. This is definitely not true for as many of the available tests as you might think would be the case.

Firstly, there is standard bloodwork and urinalysis. This is actually not all that likely show anything interesting if comparing before and after measures, especially in people who are not in their 60s or later, but it is cheap and a useful demonstration to show that nothing terrible took place. Further, some of the measures in bloodwork are needed for other parts of the testing. In particular, it is possible to see indications of tumor lysis syndrome resulting from senescent cell destruction. If there is a characteristic change in such measures immediately following use of a senolytic drug, it is an indication that something is happening, which is useful evidence.

When looking at liver function, none of the values obtained from normal bloodwork are particularly helpful. The numbers for normal function don't vary enough with age, and do vary a fair amount with circumstances and lifestyle choices. However, hepatobiliary scintigraphy results do change characteristically with age. This is a nuclear medicine procedure involving use of a radioactive tracer, so expect to pay accordingly.

For kidney function, the desired measure is glomular filtration rate. Now there are numerous ways of obtaining this result. There is the direct and expensive nuclear medicine approach with tracers, but also estimated approaches using data obtained from standard bloodwork. There are a number of resources that explain the differences in some detail, such as a PDF from the National Kidney Foundation. The estimated approaches suffer from various degrees of inaccuracy for the levels one would expect to find in a healthy individual, sad to say. The MDRD Study equation method should not be used, but the alternative CKD-EPI equation seems worth trying.

Given the evidence for a relationship between cellular senescence and calcification of blood vessels, calcium scans and scoring at first seem interesting. This is especially the case since it is apparently very hard to reduce a calcium score; it is something achieved only gradually over years, and with great attention to lifestyle changes. Calcium scans are just a standard CT scan followed by semi-automated analysis, producing an Agatston score or lesion-specific calcium score. Unfortunately, even later in life a large percentage of people score zero - as many as half or more in the late 40s and early 50s, for example. There is an online calculator from one of the research groups involved in this work if you are interested in exploring the numbers. All of this makes calcium scoring nowhere near as helpful as it might be, given the cost of a CT scan. It is probably only worth trying for people in their 70s and later, or who already have a score to hand and know it is non-zero.

Tests in lung tissue suggest that removal of senescent cells can somewhat reverse loss of tissue elasticity. So it seems worth looking at measures of skin elasticity. These can be obtained using cutometer or ballistometer commercial devices, with a number of papers commenting on reliability of the results. You might have to find a plastic surgeon or one of those dubious anti-aging clinics, however, rather than a standard dermatology practice. Possibly more useful is the indirect measure of blood vessel elasticity via pulse wave velocity, which is an easy test to arrange, and which does have a significant degree of change over the middle years of life. The question there, as with all matters cardiovascular, is the degree to which normal readings change because of primary (including the effects of senescent cells) versus secondary (weight gain and lack of exercise) causes of aging. The testing that is being accomplished here is as much of the relevance of the tests as it is of the effects of senolytic therapies. For that and other reasons, you can't just pick one test.

Another cardiovascular measure with a useful profile of changes over time is heart rate variabilility. Measurement here is also easily arranged. Of note, the Palo Alto Prize founders chose heart rate variability as their measure of aging for the interventions produced by competing teams.

Biomarkers of aging based on DNA methylation are well on the way towards becoming a practical possibility these days, though there is as yet no one consensus approach that everyone agrees upon. Nonetheless, Osiris Green is offering a DNA methylation biomarker of aging implementation at an affordable price. This is cheap enough to put into contention, even though there is as much validation of the test needed as validation of senolytics.

If you can stretch to custom lab work, then it is worth looking into the existing cellular senescence tests, or the skin sample test noted this morning, both of which require a biopsy. In the former case there are kits and the tests are well established, at least in the research community, with a question mark on how the biopsy process will interact with the role of cellular senescence in wound healing to make the results unhelpful. In the latter case, the paper provides enough details for someone to repeat the protocol, but it is anyone's guess as to how useful it will be in practice. This is another case where calibrating the test is as much the goal as calibrating the effects of a senolytic.

Pick the Senolytic Drug Candidates

Right at the start, let us throw out dasanitib, navitoclax, and similar items targeting the Bcl-2 family. They are comparatively indiscriminate chemotherapeutics, and almost everything else that the research community has identified as a potential senolytic drug is better, judging from the animal data: either more discriminating, less harmful, or both. Of the remaining compounds, it makes sense to try a combination, as some studies have suggested synergies exist between drug candidates, or that different senolytics work on different types of senescent cell. Also, the academic and corporate studies will not at the outset tend to run trials for drug combinations. It is better to raise the odds of finding interesting new data.

The compounds that seem worth looking into fall into two categories. The first are easily obtained supplement-like items that are comparatively cheap, taken orally, and well characterized for safety. In this category are fisetin and quercetin, though there is some debate over whether or not the latter is in fact senolytic. The second are more recently identified senolytics that are less easily obtained and used, in some cases with little to no human data on safety and usage, but that seem promising given recent research. Here, I'd include piperlongumine and FOXO4-DRI. In each case, you would want to read around on what is known of the pharmacology, the studies that used the compound, current thinking on how it works, and make a call on whether or not you are willing to take the risk of trying it. This will certainly involve digging through research papers, and will certainly be an individual choice. Don't blindly follow anyone's recommendations: choose for yourself.

Establish Dosage and Schedule

Figuring the likely dose for a human study involves reading the existing literature on animal studies to find the most relevant dose used there, usually expressed in mg/kg, and then multiply accordingly. You will quickly find that for most senolytics there is no easy way to come to a recommended dose, and you'll be forced to use your best judgement. For example, piperlongumine has so far only been studied in cell cultures for its effects on senescent cells. Looking at the literature, it was tested as an analgesic at levels of 1-250 mg/kg, for cancer suppression at 2.5-5 mg/kg, for sensitizing cancer to other treatments at 1 mg/kg, and for more direct cancer ablation at 2.5 mg/kg. In some cases these were single doses followed by an assessment, in others they continued for weeks.

Similarly for fisetin, there are no published animal studies for effects on senescent cells. For other purposes in past years, however, you'll find data on the pharmacokinetics for doses of 10-250 mg/kg, another study providing 10-45 mg/kg, twice a day for weeks, and yet another for cancer suppression at 5 mg/kg twice over a period of a few weeks.

For quercetin, one can look at the original study identifying it as senolytic to see that the researchers used a single dose of 50 mg/kg. For FOXO4-DRI, there is a very little data beyond the one recent study announcing its effects and another equally recent focused on cancer. Both are paywalled and unfortunately the details of the dosage are not in the main body of the original paper, but rather in the supplemental materials that I've yet to obtain. Still, it is there for consideration when I get to it.

Bear in mind that you are certainly going to want to try a very tiny dose at the outset, and then work your way up to the final dose. This precaution is only sensible and is done for a variety of reasons. In some cases these senolytic compounds are poorly or not at all tested in humans. Secondly, how certain are you that the suppliers did everything absolutely correctly, and that the testing of their compounds worked as desired? Further, if trying combinations yet to be tested in any published paper, there is always the possibility of unforeseen interactions. Lastly, if things actually work well and you started out with a high load of senescent cells, you do have to worry about the possibility of tumor lysis syndrome due to too many cells dying at once. All of these are very good reasons to ease into the desired dosage over time.

There is very definitely a spectrum of safety in the compounds I've mentioned here, from quercetin (sold in stores, manufactured by many supplement companies, in existence for years) through to FOXO4-DRI (comparatively new, barely manufactured at all, must be custom ordered, with no published human data, and only a couple of papers for animal studies). When you pick your poison, do so in full knowledge of the level of risk you undertake.

Figure out the Logistics

Quercetin and fisetin are things you put in bottles on a shelf and can leave there for months. You take the pills orally. That is all pretty easy. Piperlongumine requires freezer storage, and possibly powdering or compounding to be taken orally. FOXO4-DRI is a short lifespan protein, must be keep in freezer storage, then reconstituted and given via injection: intraperitoneal injection in mice, but most likely intravenous injection would be the most desirable option in humans. If you are familiar at all with how diabetics manage their insulin supplies, the situation is very similar.

Management of injection logistics is something that you want a lab company and probably a physician to help with, rather than embark upon it alone. In this context it is very much worth noting that, given the drug war nonsense that has gripped the world these past few decades, you want to be careful as to how you go about obtaining needles for any compounds that must be injected. This is another good reason to arrange everything in conjunction with a friendly lab company and physician.

Determine Suppliers and Order Products

Finding suppliers for the chosen senolytics varies considerably in difficulty. For quercetin, you walk across the street to pick up a few bottles from the nearest supplement store, and by going with a trusted brand can probably feel good about skipping the step of validating that the contents are what they say they are. Or you may be able to find an existing review of the supplier's products online. Fisetin can still be ordered in bottles, but here the number and quality of suppliers is more of an unknown, so the need to test the product comes into play.

For piperlongumine, you will be ordering from a chemical supplier and paying a considerable amount - hundreds of dollars for a single dose, going by the levels used in animal studies. For FOXO4-DRI, it is likely that the best course, given the very small number of suppliers, is to have it synthesized as a custom batch by a company that specializes in protein synthesis. This is expensive, and is where you will need the lab company. In both cases, suppliers will be reluctant to supply anyone they think is going to use it for human testing outside the formal trial system or a research institution.

Test the Products

You will also need the friendly lab company for the task of determining how to validate the quality of products when they arrive from the suppliers. Validation of quality is not a completely straightforward process, and may require digging up specialist services, which is better done through a company already in that ecosystem than to try it yourself. It is a matter of great importance to establish that you are getting what you pay for, both to avoid wasting the time and resources spent on the exercise of self-experimentation, as well as for reasons of personal safety. Even with the best of intentions, compounds that are not mass manufactured can have bad batches.

Run the Experiment

The first step is to run all the desired tests to obtain a set of initial baseline values. For many of these, such as standard bloodwork, it makes sense to run them twice, perhaps a few weeks apart, since numbers tend to vary with circumstances. Then follow the dosage schedule. Then run two more sets of tests, one a few days after the end of dosage, and one a month later. Precisely because many of the measures can vary with lifestyle, it is important to be consistent in your diet, exercise, and so forth across this period of time.

Then, once done, wrap it all up by publishing the data online for the community to look over.

Considering the Easy versus the Not So Easy Options

It should be apparent from reading the above notes and the linked materials that the choice of candidate senolytics and assays makes a big difference to the amount of work required to run a useful exercise in self-experimentation. It also makes a big difference to the level of personal risk undertaken. I picked the senolytics discussed in this post in part to make this point. To cut down to the easiest and safest level of self-experimentation, it would be possible to try only fisetin and quercetin and largely avoid the need for laboratory services, just relying upon a friendly physician to order bloodwork, cardiovascular, and other established tests. One could also be fairly confident that the risk of adverse effects in that scenario is lower than it is in the others. Sadly these are also the more dubious senolytic candidates; there is no such thing as a free lunch, it seems.

SIWA Therapeutics Obtains Funding to Continue with an Immunotherapy Approach to Clearance of Senescent Cells

SIWA Therapeutics is one of the older companies in the field of cellular senescence, among the small number of ventures that made an attempt to target senescent cells for destruction a decade ago and didn't really get all that far before funding ran out. Times have changed, however, and these groups have now been invigorated by progress in the science of cellular senescence and demonstrations of turning back aging and age-related disease in animal studies. One of these older ventures transformed into Unity Biotechnology, and Unity's success in raising a very large amount of venture funding has made it that much easier for everyone else with a credible approach to find backers. Between the established groups and newer ventures like Oisin Biotechnologies a wide range of potential approaches to senescent cell destruction are covered. It remains to be seen how well they all do on the later stages of the path to the clinic.

SIWA Therapeutics announced that it has successfully humanized its SIWA 318 monoclonal antibody, a significant milestone in the race to treat cancer and numerous other diseases by removing senescent cells, which become increasingly problematic as humans age. Senescent cells lose their ability to divide or replicate for a variety of reasons and also secrete chemicals which interfere with the normal functions of other cells as well as contribute to inflammation. When too many senescent cells accumulate, they can cause or exacerbate a variety of age-related and degenerative diseases.

In previous research in mice, SIWA 318 has targeted and successfully removed senescent cells, and it also increased muscle mass. Other testing showed that mice treated with SIWA 318 had fewer metastatic lung cancer occurrences as well as possible suppression of tumor growth. No adverse effects were observed from the antibody treatment in either study. The humanized form of SIWA 318 has demonstrated strong and significant binding to senescent cells in preclinical studies, critical to accurately targeting and removing them. SIWA Therapeutics just completed a new round of funding and is planning to submit an IND to the FDA, with the ultimate goal of conducting the first human clinical trials for senescent cell removal. Based on initial results, the primary focus likely will be pancreatic cancer metastasis.

"With SIWA 318 now available in humanized form, we have moved closer to determining if removing senescent cells could become a common therapeutic approach in the fight against metastatic cancers. Based on data that we and others in the scientific community have generated over the last few years, evidence is clearly mounting that many diseases, including cancer metastasis, will be treatable through senescent cell removal."

Link: http://www.businesswire.com/news/home/20170518005384/en/SIWA-Therapeutics-Takes-Key-Step-Efforts-Treat

The Basis for a Skin Sample Test of Level of Cellular Senescence

Researchers here set forth the basis for a novel approach to assessing the level of cellular senescence present in a patient, using a skin sample as a starting point. The current situation for assays of cellular senescence is very biased towards laboratory research needs, with little innovation over the past twenty years. The present standard assays are unfortunately not a suitable basis for the efficient, discriminating, and above all easy and low-cost clinical tests that will be needed in the years ahread. Senolytic therapies capable of clearing senescent cells as a form of rejuvenation treatment will become available in the next few years, and adventurous souls can already self-experiment with some of the drug candidates. Tests capable of clearly establishing the results of such experimentation are much needed.

Fibroblasts form one the most important cellular components of the skin derma. During aging, skin fibroblasts undergo substantial changes in their functional activity, morphology and proliferative potential. The number of dermal fibroblasts decreases with aging, along with their ability to synthesize active soluble factors and to maintain proteostasis of components of the intercellular dermal matrix. The skin thinning, the loss of skin flexibility and elasticity, and wrinkle formation are natural consequences of such a decline. Therefore, we suggested that evaluating the proliferative potential of dermal fibroblasts is of great significance.

Measuring the ability to form colonies in vitro represents one of the "gold standard" methods for the assessment of the clonogenic survival of cells. The method was initially developed to evaluate the loss of reproductive capacity (reproductive death) of cells after exposure to damaging agents, particularly ionizing radiation. Later it was shown that cells isolated from biopsy material from different patients had varying ability for colony formation. This allows for comparative assessment of different patient's cell capacity to proliferate and may represent a promising avenue for personalized medicine.

Beside a colony-forming efficiency of fibroblasts, defined as percentage of plated cells that are able to form colonies, the evaluation of colony size/type distribution provides additional important information especially for heterogenic cell populations such as primary fibroblasts. In this case, the size of the colony depends directly on the proliferative capacity of cell-precursors: cells can form morphologically distinct colonies that can be broken down into the following three types: dense (or compact), diffuse and mixed colonies. If the fractions of each of these colony phenotypes are known, one can evaluate the proliferative potential of the entire fibroblasts culture. Cellular aging, traditionally assessed by the fraction of senescence associated β-galactosidase (SA-βgal) positive cells, along with the degree of differentiation are closely associated with the proliferative capacity of cells. With aging, intracellular β-galactosidase accumulates in lysosomes and a sharp increase in the β-galactosidase activity in older cells is traditionally considered to be a classic marker of cellular aging. Therefore, it could be anticipated that the fraction of aging cells in colonies of the diffuse phenotype would be larger than that in the colonies of the dense phenotype.

The aim of this work was to verify the assumptions regarding the relationship of cellular aging with the formation of fibroblast colonies of different phenotypes, and to examine whether such enriched analysis of colony formation may be used for evaluating the degree of cellular senescence. To this end, we measured the fraction of SA-βgal positive cells (SA-βgal+) in the three types of colonies (dense, mixed and diffuse) of human skin fibroblasts from donors of various ages. Although the donors were chosen to be within the same age group (33-54 years), the colony forming efficiency of their fibroblasts (ECO-f) and the percentage of dense, mixed and diffuse colonies varied greatly among the donors. We showed, for the first time, that the SA-βgal positive fraction was the largest in diffuse colonies, confirming that they originated from cells with the least proliferative capacity. The percentage of diffuse colonies was also found to correlate with the SA-βgal positive cells in mass culture. Moreover, a significant inverse correlation between the percentage of diffuse colonies and ECO-f was found. Our data indicate that quantification of a fraction of diffuse colonies may provide a simple and useful method to evaluate the extent of cellular senescence in human skin fibroblasts.

Link: http://dx.doi.org/10.18632/aging.101240

A Broadening of Efforts to Clear Senescent Cells

The accumulation of senescent cells over time is one of the causes of aging. It is one of the limited number of root cause mechanisms that collectively distinguish old tissue from young tissue. Cells become senescent constantly, most because they have reached the Hayflick limit on replication, but senescence also occurs in response to cell damage, tissue injury, or a harmful tissue environment. Near all of these cells are destroyed shortly after becoming senescent, either through the programmed cell death process of apoptosis, or by the immune system. A tiny fraction linger, however. These cells generate a mix of signals and other proteins that promote inflammation, destructively remodel the nearby extracellular matrix, and change the behavior of normal cells for the worse, among other things. This all makes sense in the context of their presence in embryonic development, wound healing, and cancer suppression - and when there are comparatively few such senescent cells. When there are many senescent cells, however, and when they are not destroyed as they should be, this behavior adds up to cause significant harm. Destructive processes such as fibrosis, arterial calcification, development of atherosclerotic plaques in blood vessels, loss of tissue elasticity, chronic inflammation in joints, and many more can all be directly tied to the presence of senescent cells, and can be improved by removing those cells.

Targeted removal of senescent cells to at least some degree is in fact now fairly easy to accomplish in a laboratory setting through the methodology of targeting known suppressors of apoptosis. As a consequence a whole range of drug candidates of varying quality are emerging. The senescent cells that linger in old tissue are remain primed for the fate of apoptosis, but are held back by a few mechanisms that are increasingly well characterized. Near any established medical research group with experience in cellular biochemistry can jump in and try their hand. Clearly a growing number of researchers are doing just this, managing to raise funding and join the field. There is plenty of room for them. Clearance of senescent cells - as a rejuvenation therapy capable of turning back some of the consequences of aging - has a target market of every human much over the age of 40, for treatments undertaken once every few years. This is such an enormous potential industry that no one company or methodology will win it all. In the next few years, we'll probably see sizable and successful companies emerge in many different countries, all of which have different regulatory regimes, and thus there will be comparatively little direct competition between these ventures.

The publicity materials below are really just banging the drum for work published last year, in which researchers used ABT-737 to inhibit BCL-W and BCL-XL. These two members of the Bcl-2 family suppress the process of apoptosis. Targeting them thus selectively destroys senescent cells by removing one of the blocks to undergoing apoptosis - a manipulation that should have comparatively little effect in normal cells. Many of the apoptosis inducing drug candidates at this time have significant side-effects, however, and so it is likely that success in the market will only be achieved by those lacking that problem. At this point, the researchers here are somewhere in the early stages of commercializing their approach, and hence the emergence of extra publicity from their supporting institution. There will be a lot more of this sort of thing going on in the next few years.

Understanding why cells refuse to die may lead to treatments for age-related disease

One of the things that happens to our bodies as we age is that certain cells start to accumulate. So-called senescent cells - cells that "retire" and stop dividing but refuse to undergo cellular death - are always present, and they even serve some important functions, in wound repair, for example. But in aging organs, these cells don't get cleared away as they should, and they can clutter up the place. Researchers are revealing just how these cells are tied to disorders of aging and why they refuse to go away. The work is not only opening new windows onto the aging process, but is pointing to new directions in treatments for many of these disorders and diseases.

Research into cellular senescence has taken off in recent years, due to findings that clearing these cells from various parts of the body can reverse certain aspects of aging and disease processes. Pharmaceutical industries have taken note, as well, of research that could lead to the development of drugs that might target senescent cells in specific organs or tissues. In basic research conducted on human cell culture and on mice, researchers have asked exactly what ties senescent cells to aging. Are they, for example, a primary cause of age-related disease, or a side effect? And why don't these cells die, despite being damaged, so that the "clean-up crews" of the immune system have to clear them away?

The researchers hypothesized that the answer to the second question might lie in a family of cellular proteins that regulate a type of cell suicide known as apoptosis. They identified two proteins in this family that prevent apoptosis and which were overproduced in the senescent cells, BCL-W and BCL-XL. When they injected mice that had an extra supply of senescent cells with ABT-737 molecules that inhibit these two proteins, the cells underwent apoptosis and were then eliminated, and there were signs of improvement in the tissue. "In small amounts, these cells can prevent tumors from growing, help wounds clot and start the healing process. But as they amass, they trigger inflammation and even cancer."

Certain common age-related diseases have been shown to be associated with this build-up of senescent cells, for example, chronic obstructive pulmonary disease (COPD), and researchers hope to apply these findings to research into treatments for such diseases. The trick will be to target the offensive cells without causing undue side effects. Researchers have been developing mouse models of COPD and asking whether clearing senescent cells just from the lungs can prevent or ease the disease. They are now working to patent and license these discoveries.

Alzheimer's Disease as Laminopathy

The lack of tangible progress over the last fifteen years towards working therapies for Alzheimer's disease that are based on clearing amyloid has led to a great diversity of alternative thinking on the causes and pathology of the condition, as well as on other approaches to treatment. It is easier to theorize than it is to push therapies through trials, so this sort of thing is to be expected whenever the road ahead turns out to be much harder than expected. Some of the recent theorizing on Alzheimer's disease is quite promising, and some of it is quite dubious. From a first reading, this one falls somewhere in the middle. It should probably be read in the context of what has been discovered of the role of lamins in progeria versus in normal aging, the latter a work of investigation still very much in progress.

The cell nucleus is typically depicted as a sphere encircled by a smooth surface of nuclear envelope. For most cell types, this depiction is accurate. In other cell types and in some pathological conditions, however, the smooth nuclear exterior is interrupted by tubular invaginations of the nuclear envelope, often referred to as a "nucleoplasmic reticulum," into the deep nuclear interior. We have recently reported a significant expansion of the nucleoplasmic reticulum in postmortem human Alzheimer's disease brain tissue. We found that dysfunction of the nucleoskeleton, a lamin-rich meshwork that coats the inner nuclear membrane and associated invaginations, is causal for Alzheimer's disease-related neurodegeneration in vivo.

Neurons of tau transgenic Drosophila and of postmortem human Alzheimer's disease brains harbor significant invaginations of the nuclear envelope and have reduced levels of B-type lamin protein compared to controls. Dysfunction of B-type lamins has functional consequences in adult neurons in regard to heterochromatin formation, cell cycle activation, and neuronal survival. Taken together, our results suggest that pathological tau-induced stabilization of filamentous actin disrupts the LINC complex, which reduces lamin protein levels and causes the nuclear envelope to invaginate. Lamin reduction or dysfunction, in turn, causes constitutive heterochromatin to relax, allowing expression of genes that are normally silenced by heterochromatin and activating the cell cycle in postmitotic neurons, which causes their death.

Our findings suggest that Alzheimer's disease and associated tauopathies are, in fact, acquired neurodegenerative laminopathies. We demonstrate that loss of lamin function can lead directly to age-related neurodegeneration, indicating that basic mechanisms of aging are conserved between neurons and other somatic tissues. The lamin nucleoskeleton is thus a plausible molecular link between aging, the single most important risk factor for developing common neurodegenerative diseases, including Alzheimer's disease, and basic mechanisms of cellular senescence. Functional consequences of nucleoplasmic reticulum expansion in physiological aging and pathological conditions including cancer and Alzheimer's disease remain to be determined, however.

Link: http://dx.doi.org/10.1080/19491034.2016.1183859

Reviewing the Aging of Heart Tissue

This open access paper takes a brief tour of the dominant themes in the aging of heart tissue, viewed structurally and biochemically. These are some of the changes that have yet to be assembled into a coherent and generally agreed upon chain of events, starting with fundamental cellular damage, and proceeding through successive layers of cause and consequence in reaction to that damage. Most of the research community begins a line of inquiry with an investigation of one facet of the aged, diseased state. Researchers then attempt to work backwards to identify and address proximate causes of the observed problems, one by one, producing marginal improvements. The alternative approach of starting with fundamental damage and attempting to fix it in order to observe a resulting sweeping improvement all the way down the chain of consequences has far too little support. Note the links to the list of fundamental damage from the SENS rejuvenation research portfolio in the items below: mitochondrial damage and amyloid are mentioned directly; senescent cells and cross-linking drive harmful extracellular matrix changes; cross-linking also stiffens arteries, which produces hypertension, which in turn drives remodeling of heart structure.

The average lifespan of the human population is increasing worldwide, mostly because of declining fertility and increasing longevity. It has been predicted that, in 2035, nearly one in four individuals will be 65 years or older. With age being the dominant risk factor for the development of cardiovascular diseases, their prevalence increases dramatically with increasing age. At the end of the twentieth century, researchers announced the emergence of two new epidemics of cardiovascular disease: heart failure and atrial fibrillation. The prevalence of heart failure in the adult population in developed countries is 1-2%, which rises to more than 10% among persons 70 years or older. The same trend is seen for atrial fibrillation, with a prevalence rising from 0.12 - 0.16% in persons younger than 49 years, to 3.7-4.2% in persons aged 60-70 years, to 10-17% in persons aged 80 years or older. Since there is a clear association between aging of the population and increasing prevalence of cardiovascular disease, cardiovascular aging most likely affects pathophysiological pathways also implicated in the development of cardiovascular disease. Therefore, a better insight into cardiac aging may unravel factors implicated in cardiac pathophysiology and help towards improved prevention of human cardiovascular disease.

On a structural level, the most striking phenomenon seen with age is an increase in the thickness of the left ventricle (LV) wall as a result of increased cardiomyocyte size. This hypertrophy affects the LV in an asymmetrical way, leading to a redistribution of cardiac muscle. In the elderly, atrial contraction plays a much greater role in LV filling during diastole than in the young population. This change in function is associated with the development of atrial hypertrophy and dilation. Left atrial size has been associated with the presence of atrial fibrillation, indicating that atrial remodeling favors the development of this arrhythmia.

Remodeling at the cellular level includes a loss of cardiomyocytes and sinoatrial node pacemaker cells with age, and may contribute to the compensatory development of hypertrophy. This compensatory remodeling process may also involve changes in the composition of the extracellular matrix. The function of the extracellular matrix is to maintain the myocardial structure throughout the cardiac cycle. Hereby it plays an important role in the elastic and viscous properties of the LV. Changes in both the quantity of fibrosis and in the type of collagen fibers have been associated with old age in human hearts. It is easy to imagine that changes in the elastic properties of the LV caused by fibrosis may eventually lead to diastolic dysfunction. Indeed, in hypertensive heart disease patients, more severe diastolic dysfunction has been associated with a more active fibrotic process.

Another histopathological change found in cardiac tissue of old people is amyloid deposition. An autopsy study on a Finnish population aged 85 or over showed the presence of amyloid deposits in 25%, with a strong correlation between the presence of amyloid and the age at time of death. Amyloid found in heart of the elderly is derived from the transthyretin molecule. With age, this molecule may become structurally unstable and result in the development of misfolded intermediates that aggregate and precipitate as amyloid, mainly in the heart. In some cases, amyloid deposition in the heart occurs at a level that will lead to the progressive development of heart failure. This infiltrative cardiomyopathy is defined as systemic senile amyloidosis (SSA).

Cardiac function requires an enormous amount of energy and mitochondria are critical for the required ATP production in the myocardium. They also play a fundamental role in the survival and function of cardiomyocytes. Cardiac senescence is accompanied by a general decline in mitochondrial function, clonal expansion of dysfunctional mitochondria, increased production of reactive oxygen species (ROS), suppressed mitophagy and dysregulation of mitochondrial quality processes such as fusion and fission. Of these processes, the development of oxidative stress as a consequence of excessive ROS generation is the most frequently described phenomenon. The mitochondrial free radical theory of aging is debated, but in the context of cardiac disease, ample evidence exists for the existence of a pathogenic link between enhanced ROS production, mitochondrial dysfunction and the development of heart failure.

Link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5418492/

Replacement Heart Valve Structures that Mimic Natural Extracellular Matrix

Over the past few years, there have been a number of important advances in the infrastructure technologies needed for tissue engineering and related fields such as the construction of scaffolds to support and guide cell growth. Along these lines, researchers have recently demonstrated a rapid jet spinning approach to the construction of scaffold materials that mimic the properties of natural extracellular matrix. This allows for the construction of - to pick one example - heart valve implants, structures that will be populated by cells to form living tissue, capable of regeneration and growth, after implantation in a patient. This has been tested in animal models, and represents an improvement in cost and time over the prior standard approaches to constructing scaffolds.

Implanting scaffolds that carry chemical cues similar to those of the extracellular matrix, but lack any cells, is one of many different approaches to tissue engineering that chiefly differ from one another in where the tissue growth is expected to occur. There is a lot to be said for pushing the tissue growth stage into the body, as this works around many of the challenges inherent in trying to grow tissues outside the body: establishing all of the correct signals and environmental factors; growing blood vessel networks needed to support larger tissue sections; designing and maintaining a suitable custom bioreactor for the time it takes tissue to assemble itself; that intrusive rather than minimal surgery is required to transplant new tissue; and so on. Ultimately, I think it likely that the end goal for the tissue engineering field is to attain sufficient control over cells and cell signaling to direct the desired behavior inside the body without the need for scaffolds, bioreactors, transplantation, and other related technologies. That lies some way in the future, however. At the present time, all viable approaches that enable creation of tissue without the need for donors represent a great leap forward, a dramatic improvement over current limitations.

Engineering heart valves for the many

The human heart beats approximately 35 million times every year, effectively pumping blood into the circulation via four different heart valves. Unfortunately, in over four million people each year, these delicate tissues malfunction due to birth defects, age-related deteriorations, and infections, causing cardiac valve disease. Today, clinicians use either artificial prostheses or fixed animal and cadaver-sourced tissues to replace defective valves. While these prostheses can restore the function of the heart for a while, they are associated with adverse comorbidity and wear down and need to be replaced during invasive and expensive surgeries.

A team lead recently developed a nanofiber fabrication technique to rapidly manufacture heart valves with regenerative and growth potential. The researchers fabricated a valve-shaped nanofiber network that mimics the mechanical and chemical properties of the native valve extracellular matrix (ECM). To achieve this, the team used a rotary jet spinning technology in which a rotating nozzle extrudes an ECM solution into nanofibers that wrap themselves around heart-valve-shaped mandrels. "Our setup is like a very fast cotton candy machine that can spin a range of synthetic and natural occurring materials. In this study, we used a combination of synthetic polymers and ECM proteins to fabricate biocompatible JetValves that are hemodynamically competent upon implantation and support cell migration and re-population in vitro. Importantly, we can make human-sized JetValves in minutes - much faster than possible for other regenerative prostheses."

Another group of researchers have previously developed regenerative, tissue-engineered heart valves to replace mechanical and fixed-tissue heart valves. In their approach, human cells directly deposit a regenerative layer of complex ECM on biodegradable scaffolds shaped as heart valves and vessels. The living cells are then eliminated from the scaffolds resulting in an "off-the-shelf" human matrix-based prostheses ready for implantation. In collaboration the two teams successfully implanted JetValves in sheep using a minimally invasive technique and demonstrated that the valves functioned properly in the circulation and regenerated new tissue. "In our previous studies, the cell-derived ECM-coated scaffolds could recruit cells from the receiving animal's heart and support cell proliferation, matrix remodeling, tissue regeneration, and even animal growth. While these valves are safe and effective, their manufacturing remains complex and expensive as human cells must be cultured for a long time under heavily regulated conditions. The JetValve's much faster manufacturing process can be a game-changer in this respect."

In support of these translational efforts, a larger initiative will commence to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth. The team is also working towards a GMP-grade version of their customizable, scalable, and cost-effective manufacturing process that would enable deployment to a large patient population. In addition, the new heart valve would be compatible with minimally invasive procedures to serve both pediatric and adult patients.

JetValve: Rapid manufacturing of biohybrid scaffolds for biomimetic heart valve replacement

Tissue engineered scaffolds have emerged as a promising solution for heart valve replacement because of their potential for regeneration. However, traditional heart valve tissue engineering has relied on resource-intensive, cell-based manufacturing, which increases cost and hinders clinical translation. To overcome these limitations, in situ tissue engineering approaches aim to develop scaffold materials and manufacturing processes that elicit endogenous tissue remodeling and repair. Yet despite recent advances in synthetic materials manufacturing, there remains a lack of cell-free, automated approaches for rapidly producing biomimetic heart valve scaffolds.

Here, we designed a jet spinning process for the rapid and automated fabrication of fibrous heart valve scaffolds. The composition, multiscale architecture, and mechanical properties of the scaffolds were tailored to mimic that of the native leaflet fibrosa and assembled into three dimensional, semilunar valve structures. We demonstrated controlled modulation of these scaffold parameters and show initial biocompatibility and functionality in vitro. Valves were minimally-invasively deployed via transapical access to the pulmonary valve position in an ovine model and shown to be functional for 15 h.

Suggesting Mitochondrial Dysfunction Contributes to Age-Related Hair Loss

Researchers here investigate declining mitochondrial function in the context of hair growth, suggesting that age-related mitochondrial dysfunction is one of the causes of loss of hair in later life. Lower levels of - and less efficient - mitochondrial activity is implicated in a number of age-related diseases, especially those of the brain, where correct function requires large amounts of the energy store molecules produced by mitochondria. There appear to be several processes at work, ranging from mitochondrial DNA damage thought important in the SENS view of aging to a general and broader mitochondrial malaise that might result from dysfunctional regulation of cellular metabolism, a reaction to other forms of cell and tissue damage.

Emerging research revealed the essential role of mitochondria in regulating stem/progenitor cell differentiation of neural progenitor cells and other stem cells through reactive oxygen species (ROS), Notch or other signaling pathway. Inhibition of mitochondrial protein synthesis results in hair loss upon injury. However, alteration of mitochondrial morphology and metabolic function during hair follicle stem cells (HFSCs) differentiation and how they affect hair regeneration has not been elaborated upon.

Hair follicle (HF) is a cystic tissue surrounding the hair root, controlling hair growth. It consists of two parts: an epithelial part (hair matrix and outer root sheath) and a dermal part (dermal papilla and connective tissue sheath). The hair follicle goes through cycles of anagen phase (growth), catagen phase (degeneration) and telogen phase (rest). In the late telogen phase, hair follicle bulge stem cells differentiate into matrix cells upon stimulation, to re-enter the anagen phase. While in the catagen phase, proliferation and differentiation of hair follicle cells gradually attenuates, leaving with HFSCs and a dormant hair germ, re-entering the telogen phase.

As an essential organelle for anaerobic respiration, mitochondria attracted more research attention to its morphology and function during stem cell differentiation. Mitochondria show less mass in embryonic stem cells (ESCs) than that in differentiated cells, with a reduced oxygen consumption rate and less ROS produced. Effective control of mitochondrial morphology and function is critical for the maintenance of energy production and the prevention of oxidative stress-induced damage resulting from ROS. Besides, mitochondria play an essential role in determining hair cell differentiation and proliferation upon injury though regulating energy metabolism. In addition, ROS inhibit stem cell differentiation and proliferation through redox signaling pathway. Therefore, to counteract the adverse effect of ROS, the level of enzymes such as SOD2 is subsequently up-regulated.

We compared the difference in mitochondrial morphology and activity between telogen bulge cells and anagen matrix cells. Expression levels of mitochondrial ROS and superoxide dismutase 2 (SOD2) were measured to evaluate redox balance. In addition, the level of pyruvate dehydrogenase kinase (PDK) and pyruvate dehydrogenase (PDH) were estimated to present the change in energetic metabolism during differentiation. To explore the effect of the mitochondrial metabolism on regulating hair regeneration, hair growth was observed after application of a mitochondrial respiratory inhibitor upon hair plucking. The results revealed that disrupting mitochondrial respiration delays hair regrowth. It is possible that hair regeneration might be retarded due to insufficient energy supply. Another possibility is that mitochondrial dysfunction affects HFSCs differentiation through regulating redox balance or other signaling pathways, leading to the delay of hair growth.

Link: https://doi.org/10.7717/peerj.1821

Considering the Future of Academic Aging Research

Noted researcher Gordon Lithgow is here interviewed on the future of the aging research field. The focus is on academic funding, career, and whether or not current mainstream efforts to slow aging via alteration of the operation of metabolism in order to slow damage are the right way to go. It can be argued that the major problem in aging research is that there simply is next to no funding in comparison to other fields of medical research. The research is thus stuck moving slowly, at a point of great potential but with limited progress towards a coherent community of researchers all heading in what is definitively agreed to be the right direction for therapies to control aging. This is not because the field is currently divided and that there is much left to determine about cellular metabolism in aging, but because the funding isn't large enough to plow through these problems in a reasonable amount of time and thus quickly determine and prove which of the available options for development are actually the basis for viable human therapies.

It was odd that I ended up studying aging. I got into it not really knowing that, just seeing a profoundly mysterious process that there was no papers on, as far as I could tell. In the last 25 years, we've got textbooks on worm aging, we have signaling pathways and hormones and so, so much, it's great. But I still struggle to tell people what aging is. I tell them narratives about protein and protein insolubility during aging and how that could be driving dysfunction, but it's still hard to really say to someone, "This is what aging is". And now more than ever, beyond curiosity it's this idea that while it's been a great privilege to just be able to mess around and do science and find stuff out, actually what we've found out could be useful for people. It motivates the research somewhat, but also how I talk about the research, and my willingness to go off and do public stuff to try and turn people's heads to thinking about this. And it drives me crazy that we're training a group of scientists who are very comfortable with the biology of aging and the idea that it causes multiple diseases, who are very comfortable moving from discipline to discipline as you have to do in aging research, and unfortunately there's no jobs for these people.

Funding has been flat for 15 years in aging research. We're still here, the institute's growing. It wasn't for a while, but we're gonna be hiring again and creating some new jobs, so it's not like nothing's happening, but compared to what should be happening, and what the science is telling us we should be doing, it can be a little frustrating. We've seen our own people go to Calico and Unity Biotechnology, which is a spinout biotech from the Buck Institute that's doing very well. There have been many false dawns of aging companies and aging biotechnology going back 15 or more years, but with Calico and Unity it feels different. It feels like they're serious about finding cures to diseases based on aging technologies. And I hope they're going to be big employers.

The biggest obstacles right now is funding at every level. Translation. We've got a lot of information and compounds that we need to move forward. Obviously those two things are tightly related. Funding also is at the heart of the inability to grow the field with these new scientists. It's just so sad, people with fantastic skillsets leaving science or going into industry, and not in an aging context at all. I don't think that there's a problem with the science. In past years we could have said that there's a big problem because people don't understand the evolutionary origins of aging, or problems in the past where people were very dogmatic about it being down to one mechanism or another. And there was literally a time when many people in the field thought cellular senescence was an artefact of the culture dish and couldn't really be important in aging, because it didn't happen frequently enough in animals. And now we're at a point where we're thinking no, chances are it's really important. So a lot of the factions are melting away and you're seeing much more unity in this paradigm of what aging is.

One possibility is that most of the modifications that we've made or interventions that we've made are really just optimizing interventions. That they're not really affecting the underlying biology of aging. It's hard to draw a hard distinction between optimization and changing the underlying biology, but essentially all the models that we use, flies, yeast and worms, they all come from the same ecological niche. They all have laboratory drift and we use lab strains that aren't the same as wild strains, and during that process we may have been creating problems and shortening lifespan for years, and now all we're doing is fixing some of those laboratory-based problems. That's one view of a lot of what we've done. If that were true, it would be a bit of a crisis. It's certainly the case that we seem to be hitting some sort of upper limit with things. We don't see lifespan being extended in mice by two- or threefold, like we've seen in worms. Even in flies we haven't seen twofold life extension. It's possible that we're hitting limits in our ability to extend lifespan. I don't know.

Yet there is no biological upper limit on lifespan. We have clams living over 500 years, bristlecone pines that are living hundreds of years and things. In theory, we could all live to 122, because one human has done that. So in theory we can at least do that well, which is amazing in itself. In theory, there are mammals that live even longer than that, so we should be able to live longer than the oldest human. Clams have a circulatory system, there's a beating heart, so if there are hearts on earth that have been beating for 500 years, why not our hearts. I don't believe in biological limits, because even in human life expectancy, every time someone says there's an upper limit, someone breaks it. I don't believe in limits of that sort, but how much you have to change the human condition to attain greatly extended longevity, I don't think we know. The empirical observation so far is that it's harder to produce strong effects in more complex animals. It could be because it's just that the experiments in more complex animals are more expensive, so a tiny fraction of the experiments we've done in worms have been done in mice. It may be that we just haven't hit on it yet.

Link: http://geroscience.com/dr-gordon-lithgow-biotech-geroscience/

Excess Weight Increases Disease Risk and Shortens Life

No-one wants to hear that they are responsible for their own ill health, or that they are destroying the prospects for their own future. Thus, human nature being what it is in this era of cheap calories, there exists a thriving cottage industry based upon telling people that their excess weight is just fine and can be managed in such a way as to cause no harm. Unfortunately, that just isn't the case. Carrying excess visceral fat tissue does cause considerable personal harm: it reduces life expectancy, significantly increases risk of disease, and for all intents and purposes essentially accelerates the downward spiral of degenerative aging. You won't just be less healthy, you'll also spend more on medical services despite living a shorter life. The amount and quality of evidence that exists to support these conclusions is very hard to argue with. Nonetheless, people try, Canute against the tide.

The visceral fat tissue packed around internal organs is metabolically active, and by this point I think most people are at least passingly familiar with the idea that too much fat tissue distorts the operation of metabolism in ways that lead to metabolic syndrome and type 2 diabetes. These conditions are harmful enough over the long term that scientists have long used diabetes as a stand-in for aging in laboratory animals, a way to induce most of the consequences and conditions of aging more rapidly and thus more cheaply. In our species, type 2 diabetes is a self-inflicted condition for the vast majority of those who suffer it, caused by being overweight. It can even be turned back simply through the exercise of will power, through losing weight via a low calorie diet. It is amazing that this isn't the first thing done by every patient, rather than suffering through years of disability and medications with significant side-effects.

An excessive amount of fat tissue causes many other issues, however. It spurs chronic inflammation through its interactions with the immune system, and inflammation drives all of the common age-related diseases, especially those related to the decline in function and structure of the cardiovascular system. Excess weight also contributes to the development of hypertension, increased blood pressure, which puts further stress on blood vessels and heart tissue. Raised blood pressure is an important determinant of age-related mortality. Fat tissue also clearly drives the corrosion of the mind, as conditions such as Alzheimer's disease are strongly correlated with weight. Some of these links are mediated through the increased levels of cellular senescence produced by the presence of visceral fat tissue - recall that senescent cells are one of the root causes of aging, and more of them is a bad thing. Along the same lines, fat tissue and its activities can be linked to dysfunction of the immune system. It is just a really bad idea to get fat or stay fat: you are damaging yourself in so many ways.

'Fat but fit is a big fat myth'

The idea that people can be fat but medically fit is a myth. Early work, as yet unpublished, involved looking at the GP records of 3.5 million people in the UK. The researchers say people who were obese but who had no initial signs of heart disease, diabetes or high cholesterol were not protected from ill health in later life, contradicting previous research. A summary of their study was discussed at the European Congress on Obesity.

The term "fat but fit" refers to the alluring theory that if people are obese but all their other metabolic factors such as blood pressure and blood sugar are within recommended limits then the extra weight will not be harmful. In this study, researchers analysed data of millions of British patients between 1995 and 2015 to see if this claim held true. They tracked people who were obese at the start of the study, defined as people with a body mass index (BMI) of 30 or more, who had no evidence of heart disease, high blood pressure, high cholesterol or diabetes at this point. They found these people who were obese but "metabolically healthy" were at higher risk of developing heart disease, strokes and heart failure than people of normal weight.

No such thing as 'fat but fit', major study finds

Several studies in the past have suggested that the idea of "metabolically healthy" obese individuals is an illusion, but they have been smaller than this one. The new study involved 3.5 million people, approximately 61,000 of whom developed coronary heart disease. The scientists examined electronic health records from 1995 to 2015 in the Health Improvement Network - a large UK general practice database. They found records for 3.5 million people who were free of coronary heart disease at the starting point of the study and divided them into groups according to their BMI and whether they had diabetes, high blood pressure (hypertension), and abnormal blood fats (hyperlipidemia), which are all classed as metabolic abnormalities. Anyone who had none of those was classed as "metabolically healthy obese".

The study found that those obese individuals who appeared healthy in fact had a 50% higher risk of coronary heart disease than people who were of normal weight. They had a 7% increased risk of cerebrovascular disease - problems affecting the blood supply to the brain - which can cause a stroke, and double the risk of heart failure. While BMI results for particular individuals could be misleading, the study showed that on a population level, the idea that large numbers of people can be obese and yet metabolically healthy and at no risk of heart disease was wrong. "So-called metabolically healthy obesity is not a harmless condition and perhaps it is better not to use this term to describe an obese person, regardless of how many metabolic complications they have."

Bioprinted Artificial Ovaries Demonstrated to be Fully Functional in Mice

Researchers cannot yet produce large amounts of tissue using tissue engineering approaches such as bioprinting, as there is still no good solution for the creation of a suitable blood vessel network to support sizable tissue sections. However, that hasn't stopped the research community from forging ahead to develop the necessary recipes to produce functional tissue of various types, just in very small amounts. In many cases this artificial tissue isn't exactly the same in structure as the tissue it replaces, but it is nonetheless still capable of carrying out the desired functions. Some organs or crucial parts of organs are small enough to be produced in entirety, however, and hence researchers are now able to carry out demonstrations such the one here, in which artificial mouse ovaries are created, transplanted, and shown to be fully functional. The engineered ovaries produce the desired hormones and are capable of supporting the full process of mammalian reproduction. It is a good example of the quality of tissue being produced these days; once the blood vessel hurdle is overcome, the generation of entire organs will follow shortly thereafter.

Patients undergoing treatment regimens that eradicate their disease, such as cancer, may be left with diminished ovary function. Therefore, the oncofertility field is tasked to develop a whole organ replacement that restores long-term hormone function and fertility for all patients. In past work, we and others have sought to create an engineered ovary with biomaterials and isolated follicles. Ovarian follicles are spherical, multicellular aggregates that include a centralized oocyte (female gamete) and surrounding support cells, granulosa and theca, that produce hormones in response to stimulation from the pituitary. The spheroid shape of a follicle is critical to its survival in that the support cells must maintain contact with the oocyte until it has matured and is ready for ovulation. Consequently, a three-dimensional (3D) material environment is critical to maintaining these cell-cell interactions and follicle shape.

Thus far, there have been several reports of live births from biomaterial implants in mice, and all have used isolated follicles or whole ovarian tissue encapsulated in a plasma clot or similar fibrin hydrogel bead containing growth factor components or purified vascular endothelial growth factor. These results are very encouraging and have validated both the model procedure and the need for graft vascularization for complete restorative organ function of isolated follicles in a biomaterial. However, hydrogel encapsulation of follicles poses several challenges, especially with respect to the size of anticipated transplants. Specifically, when translating this work to a large animal or human, the implant must house a significantly larger population of follicles and therefore must be considerably larger than those used in mice. At these scales, diffusion limits may become a concern.

Future strategies must permit channels within the hydrogels (to facilitate host vasculature infiltration) or including pre-embedded vasculature to sustain follicle viability and circulate follicular hormones. Moreover, the ovary is a heterogeneous organ that compartmentalizes different follicle pools (quiescent and growing) into the cortex and medulla regions that have varying stiffness. It is believed that this compartmentalization will be critical to providing long-term (multiple decades) function with an implant. Therefore, a biomaterial strategy that can produce a mimetic construct of spatially varying material properties may be required for optimal implant function and longevity.

3D printing can be used to address all of these future implant requirements for creating a human bioprosthetic ovary, a bioengineered functional tissue replacement. As the first steps towards this goal, here, we investigated porous hydrogel scaffolds with murine follicles seeded throughout the full depth of the scaffold layers to create a murine bioprosthetic ovary. Microporous architectures were achieved through 3D printing partially crosslinked, thermally regulated gelatin. We found that specific scaffold architectures created a 3D feel by providing appropriate depth and multiple contact sites for the ovarian follicle, which resulted in optimal murine follicle survival and differentiation in vitro. The open micropores within the hydrogel scaffold provided sufficient space and nutrient diffusion for follicle survival and maturation in vitro and in vivo, as well as space for vasculature to infiltrate when implanted in vivo without the need for significant scaffold degradation as is required when using hydrogel encapsulation.

Follicle-seeded scaffolds become highly vascularized and ovarian function is fully restored when implanted in surgically sterilized mice. Moreover, pups are born through natural mating and thrive through maternal lactation. These findings present an in vivo functional ovarian implant designed with 3D printing, and indicate that scaffold pore architecture is a critical variable in additively manufactured scaffold design for functional tissue engineering.

Link: https://dx.doi.org/10.1038/ncomms15261

Comparing Regeneration of Fingertips Between Species

As a sidebar to yesterday's post on regeneration in mammals, here is a review paper that just considers fingertip regeneration in various species. This can occur in mammals, and even on rare occasions in adult humans, though it isn't well understood as to why it happens at all given the inability to regenerate most other lost appendages. It is possible that this is a useful point of investigation in order to better understand why mammals do not regenerate like salamanders, and how that state of affairs might be changed for the better.

Mammalian fingertips and toes can partially regrow under certain conditions; however, regeneration is greatly limited compared to urodele amphibians such as newts and salamanders that can completely regrow an amputated limb. The question is why there is such a difference between the regenerative potentials of mammals and amphibians. Embryonic, neonatal, and adult mice can regenerate digit tips if the amputation is midway through the third phalanx; however, if the amputation occurs proximal to the midway point of the third phalanx in mice, regeneration of the digit tip does not typically occur. Similarly, young patients have also been documented to regrow the tips of amputated fingers if treated conservatively. Although adults and even elderly individuals have potentially regenerated amputated digit tips, the regenerative process may not be as efficient as it is in younger patients and usually results in fibrous scars in adults. The regeneration process of the digit following injury may be related to the age of the host, with decreased restoration in adults compared to fetal or neonatal mammals. Injured adult mammalian tissues are usually replaced with fibrotic scar tissue, whereas scarless healing typically occurs in fetal wound healing which results in complete tissue recovery. Stem cell activation and scarless wound healing are considered to be essential requisites for quality tissue regeneration; however, for some regenerative processes a dedifferentiation process, but not stem cell activation, is required.

Many theories have been proposed to explain why successful regeneration occurs in urodele amphibians but not in mammals. First, the immune system has been shown to play a major role in the regeneration process of amputated limbs in newts. In mammals, fetal wounds can regenerate because they have an immature immune system; however, in adults, clearing pathogens appears to be evolutionarily favored compared to retaining the ability to regenerate a limb or digit. Second, amphibians have retained limb regeneration-specific genes not found in mammals, which allow their cells to dedifferentiate. A related theory is that mammals have evolved tumor suppression genes that inhibit regeneration. The Ink4a locus is present in mammals but not amphibians; this region encodes the tumor suppression genes p16ink4a and Alternative Reading Frame (ARF). Inactivation of both tumor suppressors retinoblastoma (Rb) and ARF allows terminally differentiated mammalian muscle cells to dedifferentiate. An extension of this theory is that differentiated mammalian tissues can regenerate if the cells are induced to reenter the cell cycle, which occurs in the Murphy Roths Large (MRL) mouse and the p21-deficient mouse. Third, bioelectric signaling (e.g., membrane voltage polarity, ionic channels) may also play a role in the tissues' regeneration potential. Nonregenerating wounds display a positive polarity throughout the healing process, whereas in regenerating animals the polarity is initially positive but then quickly changes to negative polarity with the peak voltage occurring at the time of maximum cellular proliferation.

Link: https://doi.org/10.1155/2017/5312951

Macrophages, and Possibly Senescent Cells, are the Keys to the Exceptional Regeneration of African Spiny Mice

In recent years, researchers have assembled a number of what appear to be important pieces of the puzzle when it comes to understanding regeneration and scarring. Why do mammals scar rather than regenerate like salamanders, and how do the exceptions to that rule function? Mutant MRL mice can heal small injuries without scarring, African spiny mice can regrow large sections of their skin without scarring, the liver can regrow sections of itself, and people can sometimes regenerate lost fingertips. It is of great interest to the medical community to come to a deeper understanding of the mechanisms of regeneration in our species and other mammals, as in principle anything that an MRL mouse can achieve in the healing of injury can be induced through suitable changes in the regulation of human regeneration. In principle, if fingertips can regenerate without scarring in some rare occasions, why can't the root causes be identified and applied to larger injuries? A fair number of research groups have for years tackled various approaches to these questions, investigating the biochemistry of regeneration in a variety of mammalian lineages and other species capable of proficient regeneration.

A picture is beginning to emerge in which the activities of senescent cells and the immune cells called macrophages are the most important players. The final assembly and details of a theory that explains all of the observed variation in regeneration remains to be accomplished, but there is a good deal of evidence to speculate upon. For example, senescent cells are known to play a temporary role in wound healing; some of their signaling is important in this respect. One of the side-effects of the recent focus on removal of lingering senescent cells as a treatment for aging is that researchers have found wound healing to be impaired when these cells are constantly cleared. Senescent cells are created in wounded tissue and serve some transient purpose before destroying themselves; if they are removed before the healing process can get underway, this slows it down. Separately, researchers have found that salamanders, known for their ability to regenerate, have a much more efficient and energetic ability to create and then entirely clear out senescent cells during regeneration.

In salamanders, the clearance of senescent cells is accomplished by macrophages, and without their presence the process of efficient regeneration runs awry. This has been shown to be the case in zebrafish as well, another species capable of healing without scarring and regeneration of body parts. Macrophages respond to injuries in mammals, and play their part in regenerative processes. There is evidence to suggest that their activities can be improved upon - researchers have altered macrophage behavior to enhance nerve regeneration, for example. Similarly, and as is the case in the research noted below, there is good evidence for macrophages to be both beneficial and detrimental to healing depending on their characteristics; some spur regeneration, others spur scarring. Given that the evidence below makes proficient regeneration in African spiny mice look very much like proficient regeneration in salamanders and zebrafish, it now seems plausible that there is a lever in here somewhere that could be used to tilt mammalian regeneration in the direction of greater capacity and lesser degrees of scarring.

Researchers Identify Macrophages as Key Factor for Regeneration in Mammals

Researchers have discovered that macrophages, a type of immune cell that clears debris at injury sites during normal wound healing and helps produce scar tissue, are required for complex tissue regeneration in mammals. Their findings shed light on how immune cells might be harnessed to someday help stimulate tissue regeneration in humans. "With few examples to study, we know very little about how regeneration works in mammals; most of what we know about organ regeneration comes from studying invertebrates or from research in amphibians and fish. If we want to apply what we learn from basic regenerative biology to humans, it would be helpful to understand what cell types and molecules regulate regeneration in a mammal where it occurs naturally."

Scientists have been trying to learn for years why some animals, like salamanders and zebrafish, are able to regrow body parts following injury, while others - like humans - can only produce scar tissue in response. Researchers learned nearly eight years ago that African spiny mice are one of the few mammalian models capable of complex tissue regeneration, making them particularly fascinating subjects. But what remained unclear was exactly how an identical injury in spiny mice and non-regenerating lab mice could produce dramatically different healing responses. The researchers decided to investigate how the inflammatory environment might differ between the regenerative response observed in spiny mice compared to the typical scarring response observed in lab mice. Although white blood cell profiles were the same in uninjured animals from both species, injury elicited different local responses. "Comparing spiny mice to common house mice, we discovered that subtypes of macrophages active during regeneration are different than those active during scarring."

When the team looked at different types of macrophages in healing tissue they found that a pro-inflammatory type of macrophage was highly abundant during scarring, but very rare during regeneration. "Our findings imply that macrophage activation in our model favors regeneration. The next step is to identify the components of macrophage activation that are necessary for regeneration. Since we are actively developing clinically feasible therapies that selectively activate macrophages, identifying targetable components of macrophage activation opens new areas of discovery with real potential for improving tissue regeneration in humans."

Macrophages are necessary for epimorphic regeneration in African spiny mice

When an animal is injured, immune cells such as macrophages rush to the wounded site to clear debris and help repair the damage. Macrophages come in different forms and subtypes, and express different protein markers on their surface, depending on where in the body they reside. Few mammals can completely renew or regrow a damaged tissue - a process known as tissue regeneration. Instead, humans and most other mammals repair injuries by producing scar tissue, which has different properties compared to the original tissue it replaces. One exception is the African spiny mouse (Acomys cahirinus), which, unlike other rodents studied, can regrow skin and fur, nerves, muscles, and even cartilage. It has been shown that in highly regenerative animals such as salamanders and zebrafish, macrophages are necessary to initiate tissue regeneration. Documented cases of tissue regeneration in mammals are rare and therefore less understood. Until now, it was not clear why two species as closely related as spiny mice and house mice would heal identical injuries in different ways.

Here, we report how the two main orchestrators of inflammation, neutrophils and macrophages, respond to injury during regeneration in Acomys cahirinus compared to scarring in the house mouse (Mus musculus). Acomys and Mus exhibit the same circulating leukocyte profiles, and we demonstrate a robust acute inflammatory response in both species. We demonstrate higher neutrophil activity in the scarring system compared to higher reactive oxygen species (ROS) activity in the regenerative system. We show that macrophages between the two species display similar in vitro properties providing a comparable baseline prior to and following injury. We also observed distinct differences in the spatiotemporal distribution of macrophage subtypes during regeneration and scarring. Finally, depletion of macrophages, prior to and during injury, inhibited blastema formation and regeneration, thus demonstrating a necessity for these cells.

A popular hypothesis to explain why most mammals heal injuries with scar tissue is that they evolved a strong inflammatory and adaptive immune response that induces intense fibrosis in lieu of regeneration. Yet, the fact that some mammals exhibit epimorphic regeneration (e.g. rodent and primate digit tips, rabbit and spiny mice ear punches and skin) suggests that regeneration can occur despite a complex adaptive immune system. It is possible that macrophages provide an initiating signal for regeneration or remove subpopulations of local cells secreting inhibitory signals (e.g. senescent cells). In support of the first idea, ROS production has been suggested as an essential early signal for regeneration based on studies in zebrafish tail models of regeneration. Macrophages are a major source of ROS after injury, and we observed significantly stronger and prolonged ROS production during regeneration compared to scarring. In support of the idea that macrophages may limit inhibitory signals through selective removal of senescent cells, recent work in salamanders suggested that clearance of senescent cells is important for limb regeneration and persistence of senescent cells during liver regeneration leads to excessive fibrosis. Furthermore, the accumulation of senescent cells with age has been suggested to shorten lifespan, degrade tissue function, and increase the expression of pro-inflammatory cytokines in mammals. These and other studies suggest that proper clearance of senescent cells from damaged tissues may promote regenerative outcomes.

Researchers Generate Improved Lung Tissue Organoids

In tissue engineering this is the age of organoids: while the challenge of generating a blood vessel network sufficient to grow large tissue sections is not yet solved, researchers are nonetheless establishing the diverse set of methodologies needed to grow functional organ tissue from a cell sample. The recipe is different for every tissue type, and there are many forms of tissue in the body. The resulting small tissue sections are known as organoids. At this time organoids are largely used to speed up further research, but for some tissue types there is the potential to produce therapies based on transplantation of multiple organoids to patch or augment failing organs. Sadly, that is probably not an option for lung disease due to the highly structured nature of lung tissue, and here the focus is on using organoids to improve the state of research. A number of groups have demonstrated functional lung organoids of increasing sophistication in the past few years, and here is the latest example in this line of research:

New lung "organoids" have been created from human pluripotent stem cells. Researchers used the organoids to generate models of human lung diseases in a lab dish, which could be used to advance our understanding of a variety of respiratory diseases. Organoids are 3-D structures containing multiple cell types that look and function like a full-sized organ. By reproducing an organ in a dish, researchers hope to develop better models of human diseases and find new ways of testing drugs and regenerating damaged tissue. "Researchers have taken up the challenge of creating organoids to help us understand and treat a variety of diseases. But we have been tested by our limited ability to create organoids that can replicate key features of human disease."

The lung organoids created in this study are the first to include branching airway and alveolar structures, similar to human lungs. To demonstrate the functionality of the organoids, the researchers showed that the organoids reacted in much the same way as a real lung does when infected with respiratory syncytial virus (RSV). Additional experiments revealed that the organoids also responded as a human lung would when carrying a gene mutation linked to pulmonary fibrosis. RSV is a major cause of lower respiratory tract infection in infants and has no vaccine or effective antiviral therapy. Idiopathic pulmonary fibrosis, a condition that causes scarring in the lungs, causes 30,000 to 40,000 deaths in the United States each year. A lung transplant is the only cure for this condition. "Organoids, created with human pluripotent or genome-edited embryonic stem cells, may be the best, and perhaps only, way to gain insight into the pathogenesis of these diseases."

Link: http://newsroom.cumc.columbia.edu/blog/2017/05/11/a-new-3d-model-for-lung-disease-made-from-stem-cells/

Dysfunction of the GABAergic System and the Aging of the Brain

Perhaps the most fearsome aspect of aging is that it degrades and ultimately destroys the function of the mind. With the exception of those who suffer neurodegenerative conditions - such as Alzheimer's disease - that in their late stages cause widespread cell death in the brain, most of the infrastructure of the mind remains largely intact even in very late life, however. This is despite the widespread small-scale damage due to broken blood vessels. The operation of that infrastructure is disrupted, however, and that disruption manifests as a progression of the various forms of cognitive decline. Analogously to the situation observed in aging stem cell populations, in which the cells are still present but not functioning as they did in youth, this suggests that some degree of restoration of lost cognitive function could be achieved rapidly if the right underlying damage could be repaired, the right signaling changed.

Cognitive aging is a consequence of molecular and biochemical aging. Alterations in gene expression, influencing the levels of proteins in many biological pathways, can be regarded as a hallmark of molecular aging. Changes in the biochemical composition of neural cells, which affect the efficiency of their synapses and whole circuits, impair the plasticity of the brain, that is the ability to reorganize, learn and remember. In this way, the disturbances of synaptic machinery profoundly contribute to the cognitive impairments as well as to the age-related brain disorders.

The majority of studies concerning the plasticity of neural circuits have focused on excitatory synapses. However, the role of inhibitory interactions in neuroplastic changes has recently been widely recognized. The most basic role of inhibitory neurons is to control the excitability of the principal cells, ensuring a proper homeostatic balance and preventing runaway excitation. Strong network inhibition suppresses the excitatory population response, providing the circuit with an intrinsic mechanism enabling precise contrast-gain control. Therefore, even though excitatory neurons are a large majority of cortical neurons, local inhibitory interneurons shape their firing and timing. There is increasing support for the hypothesis that disruption of inhibitory circuits is responsible for some of the clinical features of many neurodegenerative disorders. Many of them have been proposed to be synaptopathies - diseases related to the dysfunction of synapses. Brain aging is, in this context, considered a phenomenon promoting biological alterations associated with the above-mentioned disorders, resulting in so-called late-onset diseases.

The difficulty in understanding the mechanisms of interneurons aging, along with its relationship to plasticity impairments, cognitive decline and brain disorders, lies in the tremendous diversity of inhibitory neurons. Inhibition can be performed by perisomatically, dendritically or axonally targeting interneurons, which can be devoted to different inhibitory tasks. Furthermore, over 20 subtypes of potentially inhibitory neurons using GABA as a neurotransmitter have been recognized. Nevertheless, this diversity makes interneurons a potent and complex regulatory machinery controlling the physiology of neural circuits, and their molecular and biochemical aging can significantly contribute to the cognitive deficits observed in the aged brain. The role of neuroplasticity is to compensate for those age-related changes and to maintain the proper function of inhibitory circuits, supporting the balance between excitation and inhibition and the correct cognitive performance.

Age-related loss of synaptic contacts, decreased neurotransmitter release and reduced postsynaptic responsiveness to neurotransmitters result in a decline in synaptic strength, contributing to age-related cognitive decline. Molecular aging, defined as age-related transcriptome changes, and biochemical protein-related alterations within synapses weaken the plastic potential of neurons. Inhibitory neurons, despite being in the minority, are powerful regulators of neuronal excitability and, being particularly susceptible to aging-related alterations, are involved in many aging-induced cognitive impairments and brain disorders.

In the aged mouse somatosensory cortex, we have shown that although potential for learning-related plasticity is preserved there, the corresponding mechanisms are weakened and need longer stimulation to trigger plastic changes. We have postulated that the decreased effectiveness of the GABAergic system in the aged mouse somatosensory cortex contributes to the deficits in learning-induced plasticity. We posit that aging-induced impairments of the GABAergic system lead to an inhibitory/excitatory imbalance, thereby decreasing neuron's ability to respond with plastic changes to environmental and cellular challenges, leaving the brain more vulnerable to cognitive decline and damage by synaptopathic diseases. This is an intermediate stage of the transition from healthy aging to age-related cognitive decline and then to disease. Pharmacological and/or environmental reinforcement of the GABAergic system thus seems to be a promising therapeutic target for aging-related brain disorders.

Link: https://dx.doi.org/10.1111/acel.12605

Moving Forward with the Maximally Modifiable Mouse

One of the past projects undertaken by the SENS Research Foundation was the groundwork for a better methodology of carrying out investigative gene therapies in mice. This is called the Maximally Modifiable Mouse, and it might be thought of as a sort of mirror image of CRISPR gene editing technology: instead of bacterial genetic mechanisms normally used to defend against viruses being adapted to insert DNA into cells, is is the case for CRISPR, in the Maximally Modifiable Mouse viral genetic mechanisms normally used to attack bacteria are adapted and placed into the mouse genome to act as a docking station for the later insertion of arbitrary genetic material.

The point of the exercise is that the Maximally Modifiable Mouse technology makes it possible, or at the very least easier and less costly, to make precise genetic alterations in mice at any point in life, young or old. Most research into cellular mechanisms involves genetic engineering at some point, even if the end result for human medicine is usually some other form of intervention. It is the most effective way, and sometimes the only way, to make progress in understanding the inner workings of specific cellular processes. This engineering is still largely accomplished through the creation of altered lineages of mice rather than the application of gene therapies to normal adult mice, however. Building those lineages takes time and money, and it might be possible to cut this cost from the picture via the Maximally Modifiable Mouse. Cheaper research is faster research, and that is one of the goals of this tool.

The other important goal here is to build a system that can be used to cost-effectively test therapeutic genetic alterations aimed at rejuvenation. The obvious candidate is allotopic expression of mitochondrial genes, which requires genetic material to be delivered to the cell nucleus in order to bypass the consequences of damage to mitochondrial DNA. This is one of the root causes of aging, and allotopic expression has the potential to eliminate it. There will likely be other gene therapies to help with other forms of damage as this age of genetics moves on; perhaps the insertion of artificial enzymes capable of safely breaking down forms of metabolic waste that presently accumulate, for example. Almost any therapy that involves adding novel proteins or changing levels of existing proteins might in the future be accomplished with gene therapies at least as efficiently as via small molecule drugs - or at least once the research and development community has moved beyond its current reluctance regarding elective genetic alteration.

Creation of a "Maximally Modifiable Mouse"

We hope this project will demonstrate the feasibility of bona fide rejuvenation biotechnologies - therapies that remove, replace, repair or render harmless the pre-existing burden of cellular and molecular damage of aging in persons who have already suffered substantially from the degenerative aging process. It requires that new therapies be tested in animal models that have already undergone significant biological aging. Many of these therapies will be best demonstrated using gene therapy in animal models, and may ultimately require gene therapy for maximal efficacy in humans. Conventional transgenic animals bear their novel genes in the germ line, and although convenient methods for inducing the expression of therapeutic transgenes late in life exist, doing so still requires the custom generation of a line of transgenic animal for each new tested gene, and then allowing it to age, typically for two or more years, before the induced transgene's effects can be tested. This greatly slows down the development cycle of testing, refining, and iteratively re-testing therapeutic genes.

A promising alternative is the use of integrases from bacteriophages (or "phages,"), a class of virus whose hosts in nature are bacteria. Phage integrases are enzymes that catalyze precisely-targeted, unidirectional recombination between paired DNA recognition sequences: one (attB) a specific site in the bacterial host where the viral DNA is inserted, and another (attP) in the phage genome, from which the viral DNA is copied. Moreover, phage integrases can be used to insert arbitrary amounts of DNA into the host genome. To exploit phage integrases for gene therapy in mammals, one plasmid is generated containing the gene(s) to be inserted linked to an attB site, and another is generated containing the phage integrase; the plasmid DNA is translated in the host cell, generating the integrase, which then inserts the attB-bearing gene of interest into the host genome, with essentially no risk of gene disruption; the attP and attB sites are both destroyed in the process. The serine integrase from the mycobacteriophage Bxb1, in particular, is extremely precise: it will only mediate integration at specific attB sites. The Bxb1 integrase has already been demonstrated as a highly effective tool for somatic gene therapy in Drosophila, and has been shown to allow repeated, high-titer delivery of novel genes.

Unfortunately, mammals lack attP sites in their genomes, and thus the Bxb1 integrase cannot be used to insert new genes into mammalian model organisms such as the mouse. This limitation could be overcome with a one-time germline insertion of the Bxb1 insertion sequence into a transcriptionally-active but safe genomic location in the mouse genome: in such mice, the Bxb1 integrase system could be used at any time during the lifespan to insert therapeutic genes of any size, and with repeated rounds of gene dosing with multiple delivery methods to hit all the relevant tissues in the animals' body, with only a very low risk of mutagenesis. The effects of such genes on age-related disease could then be rapidly evaluated, and if improvements need to be made, a new transgene constructed and tested immediately in mice who are already the same age, without having to wait for a new generation of transgenic animal to be generated, born, mature, and age with every round of testing.

I'm pleased to see that the SENS Research Foundation, with funding from the Forever Healthy Foundation and other donors in our community, has started a collaboration with the Buck Institute for Research on Aging to move ahead with field testing of the Maximally Modifiable Mouse. Infrastructure projects with the potential to greatly reduce cost and time in research are one of the most important activities in any field of research. Few people pay enough attention to such work, and it rarely results in the headlines it deserves, but this sort of thing is what drives the pace of progress over the longer term.

SRF and Buck Institute to Collaborate on Gene Therapy

SENS Research Foundation (SRF) has launched a new research program focused on somatic gene therapy in collaboration with the Buck Institute for Research on Aging. Brian Kennedy, PhD, a leading expert on the biology of aging, will be running the project in his lab at the Buck. Many potential treatments of age related diseases require the addition of new genes to the genome of cells in the body, a technology known as somatic gene therapy. The technology has been hampered, up until now, by the inability to control where the gene is inserted. That lack of control resulted in a significant risk of insertion in a location that encourages the cell to become malignant.

SRF has devised a new method for inserting genes into a pre-defined location. In this program, this will be done as a two-step process, in which first CRISPR is used to create a "landing pad" for the gene, and then the gene is inserted using an enzyme that only recognizes the landing pad. SRF has created "maximally modifiable mice" that already have the landing pad, and this project will evaluate how well the insertion step works in different tissues. "Somatic gene therapy has been a goal of medicine for decades. Being able to add new healthy genes will enable us to address treatments of such age-related diseases as atherosclerosis and macular degeneration. Our collaboration with SRF will substantially move us toward finding effective treatments to genetically based age related diseases."

Decorin as a Way to Reduce Scarring During Regeneration

Researchers here present a practical method of using decorin during wound healing in order to minimize scarring. This protein appears to influence a number of mechanisms associated with fibrosis in potentially beneficial ways, but has been challenging to make use of. It is possible that this work could have applications beyond wound healing, in other areas where tissue regeneration without scar formation is desired, such as in aged organs where fibrosis is a major issue.

Scars form when the collagen scaffolding in skin is broken apart. Instead of re-forming in their original and neat basket-weave arrangement, the collagen fibres grow back in parallel bundles that create the characteristic lumpy appearance of scars. One way to reduce scarring is to apply decorin, a skin protein involved in collagen organisation. But because decorin has a highly complex physical structure it is hard to synthesise and therefore not used in the clinic.

To get round this problem, researchers have created a simplified version of decorin. They combined a small section of the decorin protein with a collagen-binding molecule and a sticky substance secreted by mussels. The resulting glue was tested on rats with deep, 8-millimetre-wide wounds. The glue was spread over each wound and covered with clear plastic film. Rats in a control group had their wounds covered in plastic without any glue. By day 11, 99 per cent of the wound was closed in the treated rats compared with 78 per cent in the control group. By day 28, treated rats had fully recovered and had virtually no visible scarring. In comparison, control rats had thick, purple scars.

Closer inspection under the microscope confirmed that collagen fibres in the treated wounds had returned to their original basket-weave arrangement. The new skin had also developed hair follicles, blood vessels, oil glands and other structures that aren't regenerated in scars. The glue is able to promote normal collagen growth because negative charges on the decorin fragments hold the fibres apart. In doing so, the fibres are more easily able to weave in and out between each other instead of sticking together randomly. The results are impressive but there is still a way to go before this can be translated to humans. "Rats have loose skin, whereas we have tight skin, and they tend to heal better and have less scarring than we do." As a result, the glue may not be as effective in people as in rats. The glue will now be tested in pigs, whose skin better resembles our own.

Link: https://www.newscientist.com/article/2130806-mussel-gloop-can-be-used-to-make-wounds-knit-without-any-scars/

An Example of Senolytic Self-Experimentation with FOXO4-DRI

Senolytic drug candidates, those demonstrated to selectively remove senescent cells to some degree in animal studies, are fairly easy to obtain. They are not enormously expensive, considered in the grand scheme of things, even those that are not yet mass-manufactured. Removal of senescent cells is a form of rejuvenation, shown to extend life in mice and reverse a number of specific measures of aging and age-related disease. These cells cause harm through the signals they generate, generating inflammation, fibrosis, and many other harmful secondary effects. Given the potential benefits, people are starting to experiment, though so far without the sort of rigor that it would be useful to see. You really have to be measuring appropriate metrics, otherwise it is all too easy to generate no useful information about the effects.

In the example noted here, I'm pleased that someone is making the effort to self-experiment in a public way - something I'd like to see more of, as this is how more organized efforts get underway. He is using the drug candidate FOXO4-DRI recently shown to interfere in the FOXO4-p53 signaling that only takes place in senescent cells. However, he isn't picking useful endpoints to measure, I think, which means that the only evidence gathered here is that this isn't horribly dangerous - always assuming that the supplier is providing what they say they are, which should be checked for compounds that are not presently mass-manufactured and widely used. Bad batches are possible, even with the best of intentions.

Useful or possibly useful items to measure might include the Osiris Green DNA methylation biomarker, bloodwork focused on markers of inflammation, kidney function, and liver function, and CT scans focused on assessing calcification of arteries. If you are not in much later life, however, the changes might be small enough to be hard to detect reliably in easily available tests such as those above, or swamped by normal day to day variation, even if the treatment is useful. Thus the best measure is to take a biopsy and have it stained using the standard research assay for senescent cell presence, but that is custom lab work and harder to arrange for most people.

A senolytic (from the words "senescence" and "lytic" - destroying) is among the class of senotherapeutics, and refers to small molecules that can selectively induce death of senescent cells. Senescence is a potent tumor suppressive mechanism. It however drives both degenerative and hyperplastic pathologies, most likely by promoting chronic inflammation. Senescent cells accumulate in aging bodies and accelerate the aging process. Eliminating senescent cells increases the amount of time that mice are free of disease. The goal of those working to develop senolytic agents is to delay, prevent, alleviate, or reverse age-related diseases. Targeting premalignant senescent cells could also be a preventive and therapeutic strategy against late-life cancer given the deteriorated efficacy of the senescence response in stopping cancer.

Senolytics are arguably the best rejuvenation therapy currently available, and though costly, FOXO4-DRI is the most effective senolytic. This site is a repository for the first human experiences with this exciting new substance. And, though anecdotal, the hope is this information will prove valuable to early adopters and science. I'm a lifelong experimenter, a member of AAAS, and proud supporter of SENS. I'm hoping the risks I'm taking will benefit many people, and advance the science. I know, I know, this is not a controlled, double-blind experiment. I am patient zero in an n=1 study. But, is there something that can be learned here? Yes, especially if I have a serious reaction or die. Alternatively, if a remarkable rejuvenation becomes evident credibility will be lent to this therapy.

Link: http://foxo4dri.com/

An Interview with Ilia Stambler on the History and Future of Longevity Science

Ilia Stambler is, I think, perhaps the foremost historian in our longevity science community at this time. That position was earned by setting forth to do the hard work of assembling a history of advocacy and efforts to extend healthy life spans. The resulting book is freely available online and well worth reading. Every movement needs its historians; without them it is all too easy to forget exactly how matters unfolded, even over timescales as short as a decade or two, never mind over centuries. If nothing else, since those who found movements and those who toil upon the incremental bootstrapping of the early years tend to be sidelined once more rapid, later stages of growth are underway, it is the case that historians are needed in order to record just who it was really carried out the hard work of making the vision a reality. This is something to bear in mind as our modern rejuvenation research community expands considerably with the advent of senescent cell clearance, including as many businesspeople as advocates and as much large-scale investment as small-scale research fundraising. Success means change, and this is a necessary part of progress, but in looking to build the future, let us not forget those who put in considerable time and effort for little reward in order to make all of this possible.

Looking back beyond the past few decades, one can uncover a few centuries of scientists and advocates who expressed what were at times surprisingly modern views on the relationship between medicine and aging - that we should attempt to extend healthy lives through progress in technology, and through addressing biological mechanisms that are important in aging. Ahead of their times, they foresaw, at least at the high level if not in detail, some of what is now possible. Unfortunately, they lived too soon to have any hope of achieving significant results. Only now, in this era of rapid progress in molecular biotechnology, do we stand upon the verge of achieving rejuvenation therapies that can be used to periodically repair the fundamental damage that causes aging. The earlier pioneers of thought and intent are also largely forgotten; history is vast in its scope, and those who study it rarely look into the narrow slices of our cultural heritage, such as those relating to views on aging. That foundation exists, nonetheless; our present movement that aims at the achievement of radical life extension was not spontaneously created thirty years ago. It is the logical continuation of numerous threads of thought and debate passed down over centuries, and only now blooming into full flower, given the technology to make the dream a reality.

Commemorating the Work of Dr. Elie Metchnikoff - Founder of Gerontology

Thank you for joining us today, Dr. Stambler. First, could you please tell us a little more about the studies of Elie Metchnikoff?

Elie Metchnikoff is the founder of the cellular theory of immunity, who showed for the first time that cells (such as phagocytes) play a vital role in immune defense. Remember that until about mid-19th century, slightly more than 150 years ago, people did not even know that cells existed or that diseases were caused by bacteria. It was just another step forward for Metchnikoff to understand that aging is a part of life that needs to be studied, and that cellular immunity, especially the immunity against one's own organism (that we now call "auto-immunity") also plays a crucial role in the aging processes.

So not only did Metchnikoff coin the term "gerontology" (the scientific study of aging) and established it as a recognized scientific field, but he in fact pioneered many seminal directions of aging research that are continued to the present, such as studying the role of auto-immunity (or inflammation) in aging, the role of intestinal bacteria (what we now often call the "microbiome") and connective tissues (such as collagen) in aging, and others. He studied the aging processes not just because they are academically intriguing (and they are), but with a clear purpose to combat or ameliorate the degenerative "disease-like" aging processes and extend healthy life. Thus we owe Metchnikoff a great debt of gratitude, not just for his concrete scientific contributions to aging research, but also as one of the founding ideologists of the truly scientific pursuit of healthy life extension, one of the essential founders of the modern intellectual and social movement for healthy longevity (or "life-extensionism").

People come to the movement for healthy longevity in different ways. What made you believe that defeating aging and age-related diseases is a worthy cause?

Metchnikoff was born in the Ukraine, then part of the Russian empire. Since the 19th century to the present, the ideas of life extension, even radical life extension, have been rather popular in Russia, in the Soviet and post-Soviet eras - perhaps more so than in the so-called "West". It was generally ideologically acceptable to want to combat destructive natural processes and improve life conditions for all. How those ideological aspirations played out in real life is a different story, and of course not everybody there embraced such aspirations. I too was born and raised in that environment and absorbed this ideology (being born in Moldova, then part of the USSR, and growing up near Moscow, before my immigration to Israel). For me it does not at all appear strange or unusual that people would want to study things that are killing them (such as destructive aging processes) in order to fight them to extend their own healthy life and the life of their loved ones. Rather it is the people who do not actively pursue these goals that appear a bit strange and unusual to me. It is such people who may need to explain themselves, and why they don't want healthy and productive life extension for themselves and others. For me such goals appear natural.

Can you please tell us about your book. "A History of Life-extensionism in the Twentieth Century" remains, I believe, a unique example of historical analysis of our movement.

Of course, there have been other histories of aging and longevity research. But mine is probably one of the more comprehensive ones, including about 1300 bibliographic notes, considering materials in several languages and national contexts (France, Germany, Russia, the UK and US, and more), and not only in the twentieth century (even though this is the focus), but from ancient times to the present. And indeed, it considers this history not just as a timeline of scientific discoveries, but as a life story of the pursuit of longevity as a social and intellectual movement, insofar as science is an inseparable part of society. Most of this research was done in preparation for my PhD thesis, and then further expanded and developed for the book. I would say it took about 7 years for the PhD completion and the additional preparations until the final product was published. It has not been easy at all, in terms of research and dissemination, and just in terms of making the living during the research and dissemination. The topic has not been very popular or "mainstream" in academia, to put it mildly... Yet, as they say, history is written and taught by the winners. I believe, as the importance of aging research and the pursuit of healthy longevity are gaining an ever increasing traction in the public and academia - so will the history of this pursuit become more sought after.

How do you define the main bottlenecks slowing down progress in the development of rejuvenation biotechnologies? What would be the best way to overcome them, in your opinion?

The main bottleneck is perhaps the general deficit in the ability or willingness of many people to invest time, effort, money and thought for the development of healthspan and lifespan extending therapies and technologies. Clearly, the more people become supportive and involved for their development, the more resources are intelligently and productively invested in it - the faster the technologies will arrive and the wider will be their availability. More worrying, in my view, are the people who already admit that the combat of aging and healthy life extension are feasible, but they still do not invest any (or any significant) intellectual or material resources to achieve these goals. I think a major bottleneck is this transition from a theoretical "belief" or "understanding" into practical action and support.

As you have been in the movement for many years, you have accumulated a significant amount of experience in advocacy. What would be your advice for people who want to get involved but don't know where to start?

The main advice for people who want to get involved in longevity research and advocacy is just: "Start getting involved" - pick yourself up and start studying, thinking and working for the cause. This may sound trivial, but this is exactly the problem of transition from theoretical "understanding" and "wishes" to practical action. Many people remain in the theoretical "wishing" stage. These pieces of advice may not seem very specific, and I wish I could state more specifically: Do this regimen, study this text, join this organization, vote to advance this legislation, or support this project - and your and everybody else's healthy longevity is guaranteed! I don't think anyone can be that specific, given the current imperfect state of knowledge, and the diversity of situations and approaches. I could just try to encourage more people to become more interested, knowledgeable, communicative and active in the field, according to their personal wishes and possibilities. From our cumulative actions, not necessarily coordinated, we may have a better chance to create the necessary "pro-longevity" gradient toward our common goal.

Reduced Efr3a Promotes Neurogenesis in the Hippocampus

The brain generates new cells at a fairly sedate pace in the process known as neurogenesis, slowly integrating newly created cells into existing neural circuits. This enables some modest degree of repair of damage, but also appears to be important in the normal operation of the mind. Modestly increased levels of neurogenesis in the brain so far seem to be wholly beneficial when examined in animal studies. Unfortunately the pace of neurogenesis slows with age, so there is some interest in the research community in finding ways to boost the process, either with or without addressing its causes. A general method of enhancing neurogenesis would probably be beneficial for cognitive function at any age, if the animal data is any guide.

New research sheds important light on the inner workings of learning and memory. Specifically, scientists show that a plasma membrane protein, called Efr3, regulates brain-derived neurotrophic factor (BDNF) / tropomyosin-related kinase B (TrkB) signaling pathway and affects the generation of new neurons in the hippocampus of adult brains. In turn, this generation of new neurons plays a significant role in learning and memory. "Our study demonstrates that Efr3a is associated with BDNF signaling and adult neurogenesis, which are important for learning and memory. We hope our results will provide new insights into the mechanisms underlying learning and memory."

To draw their conclusions, the researchers crossbred genetically altered mouse strains to delete Efr3a, one of the Efr3 isoforms, specifically in the brain. Brain-specific ablation of Efr3a promoted adult hippocampal neurogenesis by increasing survival and maturation of newborn neurons without affecting their dendritic tree morphology. Also, the BDNF-TrkB signaling pathway was enhanced in the hippocampus of Efr3a-deficient mice, as reflected by increased expression of BDNF-TrkB, and the downstream molecules, including phospho-MAPK (mitogen-activated protein kinase) and phospho-Akt. "This study once again emphasizes the extreme importance of neurogenesis specifically linked to neurotrophic signaling in the hippocampus. We are again reminded of how far we have come from the era in which neurogenesis in the adult mammalian brain was not believed to even occur."

Link: https://www.eurekalert.org/pub_releases/2017-05/foas-pmp051117.php

Interleukin-7 and Immunosenescence

Researchers here examine what is known of the role of interleukin-7 (IL-7) in the gradual decline and malfunction of the aging immune system. In the old, the immune system is both more active, producing chronic inflammation that drives the progression many of the most common age-related diseases, and at the same time less effective at carrying out its tasks. This is a major component of the frailty of old age. In the bigger picture, this is a story of molecular damage, misconfiguration of immune cells, and resulting disarray in the regulation of the immune response, but the low-level details of this progressive functional decay are still largely unmapped, such as how exactly the regulatory processes governing the immune system run off the rails.

Immunosenescence is the lifelong reduction in immunological reserve and homeostasis. This process contributes to reduced resistance to infectious diseases, increased propensity to develop cancer, and increased autoimmune disease observed in aged individuals. Furthermore, immunosenescence limits the success of medical interventions such as vaccination and efforts to augment antitumor immunity. Attempts to pinpoint a single "cause" of senescence in general and immunosenescence in particular have met with limited success. However, recent studies support a critical role for IL-7 in the maintenance of a vigorous healthspan and have identified IL-7 and its receptor and associated proteins, "the IL-7 network," as a useful biomarker of successful aging.

IL-7 is a member of the common γ chain family of cytokines. The signaling cascade(s) initiated by these interleukins and their receptors (IL-7R in the case of IL-7) regulates homeostasis of B, T, and natural killer (NK) cells of the immune system. Immunosenescence affects multiple cells within the hematopoietic lineage. The result is a gradual deterioration of immune function with age. Disruption of the IL-7 signaling pathway plays a central role in this process. In the Leiden Longevity Study, survival analysis was carried out for low versus high IL-7R gene expression in 81 nonagenarians versus the combined group of 619 of their middle-aged offspring and controls. Among nonagenarians, high IL-7R gene expression is associated with reduced mortality over 10 years; that is, higher gene expression levels of IL-7R in blood predict better survival in both age groups. Seemingly, high levels of IL-7R are beneficial. It is as if there is a limited total supply of lymphocytes that can be induced by IL-7 over a lifetime. Consuming the lymphocytes in youth and middle age provides better health, with the caveat that it may limit the possibility of living to old age. Fewer/less active lymphocytes during middle age may increase the chance of disease somewhat but result in a large enough pool of lymphocytes in old age to promote viability. Perhaps IL-7R represents a case of antagonistic pleiotropy.

The notion that low IL-7R expression levels are beneficial for reaching healthy old age corresponds with previous observations that patients suffering from autoimmune disease express increased levels of the IL-7 receptor/ligand complex genes and that antagonizing IL-7 or IL-7R may offer possible treatments. However, the results of the Leiden Longevity Study found that gene expression levels of IL-7R decrease with chronological age. On the other hand, the Leiden study also found that higher levels of IL-7R correlate with reduced 10-year mortality and that effect was pronounced in the nonagenarian population in which individuals at the high end of the overall lower IL-7R expression lived longer. To optimize health and lifespan, it may be useful to "thread the needle," lowering IL-7R enough to preserve peripheral T cells and help maintain low mTOR levels, while maintaining enough to maintain immune function. Transient modulation of IL-7R is one potentially effective strategy to reach this goal. Another possible conclusion is "correlation is not causation" and that the genes of IL-7/IL-7R complex are only part of the answer.

The remarkable plasticity of the adaptive immune system over many decades is a testament to several intrinsic features of its design. Despite attacks on its integrity from multiple angles, the size and diversity of the naive lymphocyte repertoire is maintained well into the 9th decade of life. While IL-7 is a necessary contributor to this "lympho-homeostasis" and its action is required for successful aging, wholesale augmentation of IL-7 above "normal" levels may disrupt this delicate balance. Numerous animal and several human studies suggest much promise remains for the utilization of IL-7 as a specific "immune tonic" or adjuvant. To this end, we look forward to the next generation of improved IL-7-based therapeutics.

Link: https://doi.org/10.1155/2017/4807853

Increased Adenosine Slows Cartilage Degeneration in Osteoarthritis

All age-related diseases are complex enough to have many facets through which they can be viewed, each facet being just one stage or one contributing cause, or one viewpoint on the disease process as a whole. An entire ecosystem of theory and potential therapies can be built within one facet without ever having to consider other mechanisms. Since specialization is necessary to make progress in the life sciences, this is usually how matters in fact progress: for every disease, there are many research groups with very different points of focus. The big picture must be assembled from a synthesis of all of their views.

Looking at the degenerative joint condition of osteoarthritis, for example, we might firstly consider it as an inflammatory condition. This view focuses on age-related immune dysfunction and tissue conditions that promote greater local inflammation. Therapies attempt to suppress the inflammatory response. A more recent alternative viewpoint is to see osteoarthritis as a cellular issue - one of the more direct consequences of growing numbers of senescent cells accumulating in tissues. Here, research centers on understanding how the signals generated by these cells cause such pervasive damage to joint tissue, and how to safely remove the unwanted senescent cells.

For a third facet, look no further than the papers presented below, in which osteoarthritis is considered a systemic condition in which cartilage tissue ceases to correctly regulate and maintain itself due to changes in specific signals or protein levels. Here, researchers look for proximate causes in the proteins and signals that alter with age, and seek treatments that can force restoration of a more youthful configuration. In this particular case, the researchers involved have focused on adenosine and related proteins that interact with adenosine in cartilage cells. They present evidence for the lack of adenosine to be important in the decline of aged cartilage, including a demonstration to show that delivery of additional adenosine in order to delay the onset of the symptoms of osteoarthritis in laboratory mice.

Rodents with Trouble Walking Reveal Potential Treatment Approach for Most Common Joint Disease

Researchers have provided evidence that adenosine, a biochemical at the heart of human cellular function, plays another crucial role - keeping on hand a steady number of healthy chondrocytes, the cells that make and sustain cartilage. Important to the study's implications, adenosine is derived from adenosine triphosphate (ATP), the molecule that stores the energy needed by the body's cells until they break it up to use it. Scientists have known that both inflammation and aging lead to diminished ATP production (and so lower adenosine levels) in chondrocytes. Until now, they had not linked diminished adenosine levels to osteoarthritis, the commonplace, "wear-and-tear" form of arthritis.

The study found that maintaining high levels of adenosine in rats with damage to the anterior cruciate ligament (ACL), which is known to lead to osteoarthritis in humans, prevented the rats from developing the disease. If the finding proves to be true in humans, adenosine replacement therapy could potentially delay the onset of osteoarthritis and the need for joint replacements. The findings suggest that reductions in the number of cartilage-producing cells, and greater risk for osteoarthritis, may be driven not just by lower adenosine levels but also by lower levels of the protein on the surface of chondrocytes designed to receive and pass on adenosine's signal. Adenosine helps to sustain such cells by fitting into a protein called the A2A adenosine receptor on their surfaces, like a key into a lock.

Researchers observed that mice lacking the A2A adenosine receptor did not walk as easily or as well as mice with the receptor. Radiologic examination of the knees of mice without the receptor confirmed that they had osteoarthritis. The team also found that levels of adenosine A2A receptors went up on rat chondrocytes when osteoarthritis was present, in what the researchers say was a "failed attempt" to compensate for the loss of adenosine from the energy-processing (metabolic) changes underlying the inflammation. Additional tests in tissue samples from osteoarthritic patients who had joint replacements found similarly increased levels of adenosine A2A receptors on chondrocytes.

When researchers treated mouse chondrocytes with a molecule called IL-1beta, which contributes to the development of osteoarthritis, they found that 39 percent less ATP was produced by the inflamed chondrocytes. They also found 80 percent less expression of ANKH, a molecule that exports ATP, in the IL-1beta-treated cells. Finally, they found that lacking the enzyme involved in turning ATP into adenosine caused diminished adenosine levels, which led to osteoarthritis in mice. The lack of the enzyme in humans is also known to lead to the disease. When the team administered adenosine packaged in lipid bubbles into rats' ACL injuries, researchers found that the excess adenosine, as mediated by the adenosine A2A receptor, prevented the development of osteoarthritis in the animals.

Endogenous adenosine maintains cartilage homeostasis and exogenous adenosine inhibits osteoarthritis progression

Osteoarthritis (OA) is characterized by changes in every structure in the joint, including cartilage destruction, synovial inflammation, osteophyte formation, enthesophytes, and significant bony changes. The central player in OA is the chondrocyte, which responds to excess mechanical loading by releasing inflammatory mediators and proteolytic enzymes causing further cartilage damage. In addition, age-related inflammation contributes to the pathogenesis of OA.

Adenosine is an endogenously produced physiological regulator and its intracellular and extracellular concentration is tightly controlled by oxygen consumption, cellular stress and mitochondrial functionality. Extracellular adenosine derives mainly from hydrolysis of ATP and mediates its effects via activation of G-protein-coupled receptors (A1R, A2AR, A2BR and A3R). Adenosine has long been known to regulate inflammation and immune responses and work from our lab and others have demonstrated the importance of adenosine and its receptors in osteoblast, osteoclast, and bone marrow homeostasis. Prior studies have suggested that adenosine receptors also regulate chondrocyte physiology and pathology in response to inflammatory stimuli although the specific receptor(s) involved are not identified. Removal of endogenous adenosine or blockade of A2AR leads to cartilage degradation in equine tissue. A3R stimulation has been reported to diminish OA development in a chemically induced model of OA, principally due to the anti-inflammatory effects of A3R agonists.

The results presented here provide evidence for a critical homeostatic mechanism in cartilage. Chondrocytes release ATP which is converted to adenosine extracellularly; the adenosine that is present prevents the phenotypic changes in chondrocytes associated with development of OA via engagement of A2AR. Disruption of this mechanism, as a result of inflammation, injury or aging with reduction of intracellular and extracellular ATP and extracellular adenosine, leads to phenotypic changes in chondrocytes with greater expression of matrix metalloproteinases (MMPs) or collagens associated with cartilage hypertrophy. Moreover, these studies demonstrate that replacement of adenosine by intra-articular injection of liposomal preparations of adenosine can restore the homeostatic equilibrium to cartilage following injury by engagement of A2AR. We conclude that adenosine, acting at A2AR, is an important homeostatic regulator of chondrocytes and cartilage and adenosine repletion may represent a novel approach to treating OA.

The Aging of Lymphatic Vessels

All of the the body's systems are impacted by aging. Damage to cells and tissues occurs as a consequences of the normal operation of metabolism, and leads to a chain of cause and consequence that ultimately produces functional declines and age-related disease. While the root cause of aging consists of only a few different forms of damage, how that damage then spreads into dysfunction is very different for every tissue and organ. Aging may have simple causes, but its progression is enormously complex and still far from completely mapped. Here, researchers review what is known of the aging of the lymphatic system. That there was a lack of detailed information until quite recently is not an unusual state of affairs, and is also the case for many other important systems in the body:

Lymph flow is necessary for vital functions, such as fluid and macromolecule homeostasis, absorption of lipids and transport of immune cells. All of these functions require proper functioning of the lymphatic vessels - their phasic contractions that propel lymph forward to central veins, proper permeability and interaction with cellular elements of the surrounding tissue microenvironment. Aging affects all of these functions of lymphatic vessels. However, despite findings of the last decades, our understanding of key regulatory mechanisms that support lymphatic vessel functions is still far from complete. The field of lymphatic biology has historically encountered difficulties in the assessment of lymphatic vessel function in vivo and in obtaining lymphatic vessels for studies in vitro. These difficulties have overlapped with an underappreciation of the importance of the lymphatic vascular component of the pathogenesis of various disorders in the past. Therefore, the lymphatic-related components in the pathogenesis of many diseases of the elderly remain to a large degree unknown.

Until the last decade, there were no published reports of systematic studies on aging-associated changes in the lymphatic vasculature. One study, published more than two decades ago, examined aging-associated changes in the structure of human lymphatic vessels. These authors demonstrated that in older humans, the destruction of the elastic elements and atrophy of muscle cells in the thoracic duct wall resulted in the development of "duct sclerosis." Investigations of the human mesenteric lymphatic bed demonstrated that after the age of 65, the number of collecting lymphatic vessels in the human mesentery was significantly reduced, and the number of connections between lymphatic vessels was greatly diminished. In some preparations of collecting lymphatic vessels, aneurism-like formations containing only endothelial cells in their walls were found, primarily in the areas located downstream but close to the lymphatic valves. Due to the profound difficulty of measuring lymph flow in vivo, there are only a few reports demonstrating measurements of reduced lymph flow in aged animals. In particular, it was reported that aging significantly reduced lymph flow from the main mesenteric lymph duct in rats by ~60% when compared between 3-month-old and 22-month-old animals.

Over the last decade, our group has performed a wide spectrum of studies significantly expanding our knowledge on how and by which mechanisms aging alters the structure and function of lymphatic vessels. These recent findings have led to a better understanding of the regulatory mechanisms of interactions between lymphatic vessels and mast cells (MCs) located in perilymphatic tissues, and demonstrated their importance for the control of all lymphatic functions mentioned above. We believe that these new discoveries provide the groundwork for a better understanding of the pathogenesis of many diseases in the elderly that involve a lymphatic component.

Our studies during the last decade have demonstrated that aging alters the structure and contractile function of lymphatic vessels. These changes are complex and predispose aged lymphatic vessels to diminished lymphatic contractility and lymph flow, especially during edemagenic challenges in the event of overlapping acute inflammation in the elderly. In addition, aging creates conditions for the easier spread of pathogens from lymphatic vessels into perilymphatic tissues. Aging induces the basal activation of perilymphatic MCs, which, in turn, restricts the recruitment/activation of several types of immune cells in perilymphatic tissues. Activated MCs trigger NF-κB signaling through the release of histamine. The aging-associated basal activation of MCs limits acute histamine-driven inflammatory NF-κB activation in aged perilymphatic tissues. Therefore, aging-associated dysfunction of MCs critically affects all NF-κB-mediated reactions of aged tissues to acute inflammation. Proper functioning of the mast cell/histamine/NF-κB axis is essential for the regulation of lymphatic vessel transport and barrier functions, as well as for both the interaction and trafficking of immune cells near and within lymphatic collectors. Thus, this axis appears to play important roles in the pathogenesis of the alterations in inflammation and immunity associated with aging.

Link: http://dx.doi.org/10.3390/ijms18050965

Exercise Correlates with Longer Average Telomere Length

Average telomere length as presently measured in white blood cells is a terrible measure of biological age. The pattern of decreasing length over time only shows up in statistical data over large populations, and even then you'll find studies in which this doesn't happen. For any given individual, this measure is quite dynamic on short timescales, can vary widely from that of peers of the same age and health status, and because of this a value established at any given point in time isn't really actionable information. Still, telomere length is cheap and easy to measure these days, so researchers persist in using it. I'm hoping to see its commonplace use replaced in the years ahead with one of the DNA methylation biomarkers of aging currently under development, as they are far more promising and potentially useful.

Telomeres are stretches of a repeated DNA sequence at the ends of chromosomes, some of which is lost with each cell division. This is a part of the mechanism that limits the number of divisions in the somatic cells that make up the vast majority of cell counts by tissue in the body. When telomeres become too short, a cell self-destructs or becomes senescent. In either case it ceases to replicate. New somatic cells with long telomeres are periodically generated by stem cell populations to make up the losses. So average telomere length in any given tissue is determined by some combination of replication rate and stem cell activity. It is known that stem cell activity declines with age, but in white blood cells the pace of replication varies widely with health status as well. So it is a very fuzzy metric.

All that said as a caution, it is interesting to look at the results of this study in the context of other recent work that attempts to quantify the dose-response curve for exercise. It has been suggested by other research groups that more than the recommended 30 minutes a day of regular moderate exercise is needed in order to obtain optimal benefits. As for all such statistical studies, it is a poor idea to take the results from any one paper as ironclad truth, however. Looking at the field as a whole is required, to see where the weight of evidence falls.

Despite their best efforts, no scientist has ever come close to stopping humans from aging. But new research reveals you may be able to slow one type of aging - the kind that happens inside your cells. As long as you're willing to sweat. "Just because you're 40, doesn't mean you're 40 years old biologically. We all know people that seem younger than their actual age. The more physically active we are, the less biological aging takes place in our bodies." The study finds that people who have consistently high levels of physical activity have significantly longer telomeres than those who have sedentary lifestyles, as well as those who are moderately active.

Telomeres are the protein endcaps of our chromosomes. They're like our biological clock and they're extremely correlated with age; each time a cell replicates, we lose a tiny bit of the endcaps. Therefore, the older we get, the shorter our telomeres. Researchers found that adults with high physical activity levels have telomeres with a biological aging advantage of nine years over those who are sedentary, and a seven-year advantage compared to those who are moderately active. To be highly active, women had to engage in 30 minutes of jogging per day (40 minutes for men), five days a week. "If you want to see a real difference in slowing your biological aging, it appears that a little exercise won't cut it. You have to work out regularly at high levels."

Researchers analyzed data from 5,823 adults who participated in the CDC's National Health and Nutrition Examination Survey, one of the few indexes that includes telomere length values for study subjects. The index also includes data for 62 activities participants might have engaged in over a 30-day window, which the researchers analyzed to calculate levels of physical activity. The study found the shortest telomeres came from sedentary people - they had 140 base pairs of DNA less at the end of their telomeres than highly active folks. Surprisingly, he also found there was no significant difference in telomere length between those with low or moderate physical activity and the sedentary people. Although the exact mechanism for how exercise preserves telomeres is unknown, it may be tied to inflammation and oxidative stress. Previous studies have shown telomere length is closely related to those two factors and it is known that exercise can suppress inflammation and oxidative stress over time.

Link: http://news.byu.edu/news/research-finds-vigorous-exercise-associated-reduced-aging-cellular-level

Confirming Age-Associated B Cells as an Important Cause of Autoimmunity

Most of the better known and more common forms of autoimmune disease are not all that age-related, though incidence for many of them ticks upwards with age as the immune system becomes ever more dysfunctional in later life. There are many more autoimmunities that are age-related, however, mostly comparatively poorly understood, and new ones are discovered on a fairly regular basis. It is fair to say that autoimmunity as a whole is poorly understood, however. The immune system is enormously complex, and it remains to be established as to how exactly it falls into the malfunctioning states that cause it to attack specific tissues, cells, and proteins that it should normally leave alone. It is unlikely that there is any one root cause, but the hope in the research community is that the broad range of quite different autoimmunities do in fact have commonalities, as is the case for cancer. Just as in cancer research, meaningful progress in the medical control of autoimmunity will likely hinge on identification and targeting of mechanisms shared by many or a majority of the diseases in this category.

One of the most promising approaches to autoimmunity is to bypass the investigation of its mechanisms and just destroy the entire population of adult immune cells. The state-related data of the immune system, such as its memory, and including the errors that cause it to attack tissues rather than pathogens, is stored entirely in those cells. Wiping it clean and starting over has been shown to cure multiple sclerosis, for example. Unfortunately this is a fairly risky and damaging process at the moment, given the harsh nature of the high-dose immunosuppressants required, which makes it unsuitable for all but the most dangerous autoimmune conditions. One path forward is to produce better targeted cell-killing technologies, therapies that lack side-effects, and that is certainly a going concern in the biotechnology community. Look at the past decade of work emerging from the cancer research community, for example, or the programmable gene therapy cell destruction approach pioneered by Oisin Biotechnologies. Such a side-effect-free therapy would still leave the patient without a functioning immune system for a period of time, however, which would add considerably to the support needed to make such a treatment safe enough for widespread use, especially in older people.

What if a much smaller population of errant immune cells could be identified and selectively destroyed, however? The autoimmunity could be suppressed or removed without having to purge the entire immune system, and that could possibly be achieved to a good enough degree with existing technologies. That is the promise offered by research into age-associated B cells, a class of dysfunctional immune cell discovered not so many years ago. In the paper and publicity materials noted here, an important role for these cells appears to be confirmed for a range of classes of autoimmunity. This seems to me to be an noteworthy step forward in the field, and opens a number of paths towards forms of effective treatment for autoimmune conditions.

Trigger for Autoimmune Disease Identified

Researchers have identified a trigger for autoimmune diseases such as lupus, Crohn's disease and multiple sclerosis. The findings help explain why women suffer autoimmune disease more frequently than men, and suggest a therapeutic target to prevent autoimmune disease in humans. "Our findings confirm that Age-associated B Cells (ABCs) drive autoimmune disease. We demonstrated that the transcription factor T-bet inside B cells causes ABCs to develop. When we deleted T-bet inside B cells, mice prone to develop autoimmune disease remained healthy. We believe the same process occurs in humans with autoimmune disease, more often in elderly women."

B cells are important players in autoimmune disease. The research team previously identified a subset of B cells that accumulate in autoimmune patients, autoimmune and elderly female mice. They named the cells Age-associated B cells, or ABCs. Subsequent research showed that the transcription factor T-bet plays a crucial role in the appearance of ABC. Transcription factors bind to DNA inside cells and drive the expression of one or several genes. Researchers believe that T-bet appears inside cells when a combination of receptors on B-cell surfaces - TLR7, Interferon-gamma and the B-cell receptor - are stimulated.

Through breeding and genetic techniques the research team eliminated the ability of autoimmune-prone mice to express T-bet inside their B cells. As a result, ABCs did not appear and the mice remained healthy. Kidney damage appeared in 80 percent of mice with T-bet in the B cells and in only 20 percent of T-bet-deficient mice. Seventy-five percent of mice with T-bet in their B cells died by 12 months, while 90 percent of T-bet-deficient mice survived 12 months. "Our findings for the first time show that ABCs are not only associated with autoimmune disease, but actually drive it."

B cells expressing the transcription factor T-bet drive lupus-like autoimmunity

B cells are known to be involved in different aspects of autoimmune diseases and may contribute in a number of ways including the secretion of autoantibodies, processing and presentation of autoantigen to T cells, and production of inflammatory cytokines. Therefore, B cells are promising targets for treatment of autoimmune diseases. Indeed, this idea has been put into practice and B cell depletion therapy has been tested for multiple autoimmune diseases. It is not yet known why B cell depletion is effective for some but not all diseases and for some but not all patients with a particular malady. One possibility is that the depletion therapies might not affect all B cell subsets equally well and different diseases, or different patients, might have involvements of different B cell subsets.

A novel subset of B cells named age-associated B cells (ABCs) has recently been identified by others and ourselves. Unlike other B cells, ABCs express high levels of CD11c and the transcription factor T-bet. T-bet was subsequently demonstrated to be necessary and sufficient for the appearance of this subset, and triggering of the B cell antigen receptor (BCR), IFN-γ receptor (IFN-γR), and TLR7 on B cells induces high levels of T-bet expression. Our previous data demonstrated that T-bet+ ABCs appear in autoimmune patients and in autoimmune-prone mice. These cells produce high amounts of autoantibodies upon stimulation in vitro, suggesting that they are major precursors of autoantibody-secreting cells.

Moreover, our recent findings indicate that ABCs are very potent antigen-presenting cells and therefore might participate in autoimmune responses by presenting self-antigen to autoreactive T cells. In agreement with our findings, a recent study demonstrated elevated levels of T-bet expression in B cells obtained from peripheral blood mononuclear cells of lupus patients when compared with healthy donors, suggesting that T-bet expression in B cells may be critical for the development of lupus in humans. Others have reported that T-bet-expressing B cells are associated with Crohn's disease activity, and an increased expression of T-bet in B cells was found in a patient with MS and celiac disease, altogether suggesting an important role for T-bet-expressing B cells in human autoimmunity.

Therefore, we hypothesized that ablation of ABCs will prevent or delay the development of lupus-like autoimmunity. We tested this hypothesis by conditionally deleting T-bet from B cells in a mouse model of lupus. Our data demonstrate that this deletion leads to reduced kidney pathology, prolonged survival, and delayed appearance of autoantibodies in these mice. Moreover, our data suggest that T-bet expression in B cells is required for the rapid formation of spontaneous germinal centers that develop without purposeful immunization or infection during such autoimmune responses. The results indicate a critical role for T-bet expression in B cells for the generation of efficient autoimmune responses and the development of lupus-like autoimmunity, and suggest that specific targeting of T-bet+ B cells might be a useful therapy for some autoimmune diseases.

Thioredoxin Reductase Correlates with Species Longevity

Researchers here summarize current data on thioredoxin reductase and longevity across a range of species, finding a correlation for the mitochondrial variant of this protein. There are numerous proteins for which one can point to correlations with species life span, and some of them relate to mitochondria and oxidative metabolism, as is the case here. What we should take away from this, and related research, is that there is a great deal of evidence pointing towards the importance of mitochondria in the way in which the operation of cellular metabolism determines the pace of aging. That in turn means that greater emphasis should be placed on research such as the SENS rejuvenation research programs that offer the prospect of protecting mitochondria from damage, preventing their age-related decline and hopefully minimizing the role they play in causing aging.

The rate at which aging leads to physiological decline, late-life disease, and death varies greatly among species of birds, rodents, and primates. Maximum lifespan varies from 2 years to over 100 years among species of mammals. This variation is thought to represent adaptation, across evolutionary timescales, to niches that reward either rapid reproduction or slower, more sustained patterns of development and reproductive investment. This variation in lifespan can be seen not just across the animal kingdom but within individual animal clades. Maximum lifespan among nonhuman primate species varies from 15 to 60 years. Maximum lifespan among rodent species varies from 4 to 32 years, and maximum lifespan among bird species varies from 5 to 70 years. This implies that a long lifespan has evolved multiple times in different clades. What strategies have been employed by these different groups to extend lifespan and whether these strategies are conserved or divergent among animal clades forms an interesting topic for research. Understanding the mechanisms that different species have employed to extend their lifespan has both medical implications for developing treatments to age-associated diseases.

Comparative analysis of cultured cells from species that vary in lifespan provides a powerful tool to identify factors which may regulate the rate of aging. Much circumstantial evidence links cellular resistance to oxidative stress and organismal lifespan. Genetic, dietary, or drug manipulations that extend lifespan in mice, flies, and worms often increase oxidative stress resistance. Cells from longer-lived species are often more resistant to oxidative stress than cells derived from shorter-lived species of the same clade. Increased resistance to oxidative injury seems often to accompany increased longevity, but to be insufficient to increase lifespan on its own, as demonstrated by the catalase overexpression is targeted to mitochondria, hinting that mitochondrial antioxidant defenses might be of particular importance, rather than oxidation elsewhere in the cell.

Thioredoxin (TXN) is a small redox protein which both removes oxidants and free radicals from the cellular environment and reduces protein disulfide bonds once these are formed. Thioredoxin reductase (TXNRD) reduces oxidized TXN thioredoxin while simultaneously catalyzing conversion of NADPH into NADP+. Thus, TXNRD controls the availability of reduced TXN. The TXN/TXNRD pathway also represses apoptosis through inhibition of ASK-1 signaling. In mammals, there are three forms of thioredoxin reductase: cytosolic TXNRD1, mitochondrial TXNRD2, and TXNRD3, whose function is poorly defined. In Drosophila, there are two forms of thioredoxin reductase: cytosolic Trxr-1, an orthologue of TXNRD1, and mitochondrial Trxr-2, an orthologue of TXNRD2.

In this report, we show a correlation between TXNRD enzyme activity and species lifespan using fibroblasts from birds, rodents, and primates. In some clades, we found similar associations with glutathione reductase activity, but did not see a correlation for any of the other redox enzymes evaluated. The increase in TXNRD activity in the longer-lived species is due to enhanced mitochondrial TXNRD2 with no change in cytosolic TXNRD1 or TXNRD3. A similar increase in TXNRD2 is seen in tissues of several models of enhanced longevity in mice, and in an analysis of mRNA levels from multiple tissues of primate species. Lastly, we demonstrate that overexpression of mitochondrial TXNRD2, but not cytosolic TXNRD1, can extend median (but not maximum) lifespan in female flies with a small lifespan extension in male flies in Drosophila melanogaster.

These data demonstrate that augmentation of mitochondrial thioredoxin reductase 2 is a conserved approach utilized by species from a range of animal clades under selection for a long lifespan. Furthermore, we demonstrate directly that augmentation of this enzyme is able to extend organismal lifespan in Drosophila melanogaster. Our approach shows the power of combining comparative biology cross-species approaches with direct interventions in model organisms as a means of discovering regulators of aging and lifespan. In addition, we identify mitochondrial Thioredoxin reductase 2 as a new target, for basic and applied research in aging.

Link: http://onlinelibrary.wiley.com/doi/10.1111/acel.12596/full

An Exploration of Mechanisms of Hair Greying, but not Yet Linked to Aging

This research is an example of the way in which both the mainstream press and research publicity materials are sometimes quite terrible. The researchers involved have explored some of the cellular biochemistry that is necessary to the pigmentation of hair. They demonstrate, as you might expect, that sabotaging these mechanisms results in grey hair. What they have not yet accomplished is to show that aging has an impact on the specific mechanisms examined in this research. Maybe it does, maybe it doesn't. While the research looks like a promising lead, all things considered, age-related graying of hair might well be caused by processes operating somewhere else in the generation of pigmentation. So it is premature to be claiming identification of the causes of loss of hair pigmentation with age, as has been the case where this research was reported.

"Although this project was started in an effort to understand how certain kinds of tumors form, we ended up learning why hair turns gray and discovering the identity of the cell that directly gives rise to hair. With this knowledge, we hope in the future to create a topical compound or to safely deliver the necessary gene to hair follicles to correct these cosmetic problems." The researchers found that a protein called KROX20, more commonly associated with nerve development, in this case turns on in skin cells that become the hair shaft. These hair precursor, or progenitor, cells then produce a protein called stem cell factor (SCF) that the researchers showed is essential for hair pigmentation. When they deleted the SCF gene in the hair progenitor cells in mouse models, the animal's hair turned white. When they deleted the KROX20-producing cells, no hair grew and the mice became bald.

The researchers serendipitously uncovered this explanation for balding and hair graying while studying a disorder called Neurofibromatosis Type 1, a rare genetic disease that causes tumors to grow on nerves. Scientists already knew that stem cells contained in a bulge area of hair follicles are involved in making hair and that SCF is important for pigmented cells. What they did not know in detail is what happens after those stem cells move down to the base, or bulb, of hair follicles and which cells in the hair follicles produce SCF - or that cells involved in hair shaft creation make the KROX20 protein. If cells with functioning KROX20 and SCF are present, they move up from the bulb, interact with pigment-producing melanocyte cells, and grow into pigmented hairs. But without SCF, the hair in mouse models was gray, and then turned white with age, according to the study. Without KROX20-producing cells, no hair grew.

The researchers will now try to find out if the KROX20 in cells and the SCF gene stop working properly as people age, leading to the graying and hair thinning seen in older people - as well as in male pattern baldness. The research also could provide answers about why we age in general as hair graying and hair loss are among the first signs of aging.

Link: http://www.utsouthwestern.edu/newsroom/news-releases/year-2017/may/gray-hair.html

Enhanced Autophagy as a Potential Basis for Treating Neurodegenerative Conditions

The consensus in the scientific community is that useful therapies can be built on the safe enhancement of autophagy. This has been the case for many years now, but unfortunately, and despite a broad and ongoing range of research initiatives, there has yet to be any significant progress on the path from laboratory to clinic in this part of the field. Even simple, easily explained adjustments to the operation of metabolism turn out to be involved and costly projects. They take a long time to come to fruition, and when considered individually have poor odds of success. Look no further than the past two decades spent in search of calorie restriction mimetic drugs for proof of that point: for all the enormous sums spent and years of work this is still a field of candidate therapies characterized by marginal results, mixed evidence, and side-effects that would in any case make them impractical for widespread use. If you want to enhance the operation of autophagy, the actual practice of calorie restriction remains the only viable, reliable option at this time, and that falls far short of the level of enhancement that might be both possible and optimal when considering the bigger picture.

Why is more autophagy a good thing? Autophagy is a collection of processes responsible for recycling of damaged cellular structures and macromolecules, as well as removing some forms of unwanted metabolic waste. Damaged machinery inside the cell produces more damage the longer it is left intact; having less damaged and more functional cells at any given time throughout the body adds up over time. Many of the interventions demonstrated to slow aging in laboratory animals feature enhanced autophagy among the changes they produce in the operation of metabolism. In at least one case, that of calorie restriction, autophagy has been shown to be necessary for the health and longevity benefits observed in normal animals to take place. There is a great deal of evidence, both direct and indirect, for autophagy to one of the more important determinants of the natural pace of aging.

Given the prominent role of metabolic waste, such as amyloid aggregates, in age-related neurodegenerative conditions, it is understandable that a sizable fraction of research into autophagy is carried in the context of cellular dysfunction in neurodegeneration. Autophagy is known to decline with age, in part a consequence of the presence of hardy metabolic waste that cannot easily be broken down, and that clogs the system, reducing its effectiveness. Researchers are searching for ways to restore autophagy to youthful levels, mostly aiming for the alteration of regulatory processes or related mechanisms in order to increase autophagic activity without addressing the reasons for its decline. In fairness, this has been proven quite effective in some animal studies, but I'd still favor the approach of addressing the root causes first of all, then move on to enhancement. In this context, the open access paper here is a fairly standard overview of present thinking in the research community when it comes to autophagy and the treatment of neurodegenerative disease. That more or less amounts to more of the same work from the last twenty years, so I'd say don't hold your breath expecting stunning results any time soon on this front.

Therapeutic implication of autophagy in neurodegenerative diseases

Autophagy, a catabolic process to maintain intracellular homeostasis, has been recently focus in numerous human disease conditions, such as aging, cancer, development, immunity, longevity, and neurodegeneration. However, sustaining autophagy is essential for cell survival and dysregulation of autophagy is anticipated to speed up neurodegeneration progression; although, the actual molecular mechanism is not yet fully understood. In contrast, emerging evidence suggests that basal autophagy is necessary for removal of misfolded aggregation proteins and damaged cellular organelles through lysosomal mediated degradation. Physiologically, neurodegenerative disorders are related to the accumulation of amyloid β peptide and α-synuclein protein aggregation in Alzheimer disease and Parkinson disease, respectively. Even though autophagy could impact several facets of human biology and disease, however it functions as a clearance for toxic protein in the brain contributes us novel insight into the pathophysiological understanding of neurodegenerative disorder. In particular, several studies demonstrate that natural compounds or small molecule autophagy enhancer stimulates autophagy which is essential in clearance amyloid-β (Aβ) and α-synuclein deposits.

As a therapeutic purpose, it has been indicated that upregulation of autophagy through mTOR complex 1-mediated pathway might be targeted to removal of aggregate protein molecules and decrease cytotoxicity in animal models. However, tauopathies, α-synucleinopathies, and other models has been implicated to treat neurodegenerative disease through this strategy. In particular, mTOR-independent autophagy inducers rapamycin analogs such as rilmenidine and trehalose drugs has been used in these diseases. On the other hand, autophagy inhibitor increases the toxicity of these protein that leads to enhance of the relevant protein during neurodegeneration. It is also mention that rapamycin and its chemically synthesized analogues such as CCI-779 are widely used potential activator of autophagy in yeast and mammalian cells in neurons as well as in vivo in mouse brain. Eventually, widespread preclinical animal model studies are required to induce autophagy in neurodegenerative disease.

Furthermore, statins, a class of lipid-lowering medications, induces autophagy in astrocytes through AMPK-mTOR mediated pathway and it has been suggested that autophagy is essential in insulin-degrading enzyme secretion, thus modulation of autophagy could provide a possible therapeutic approach in Aβ pathology by increasing clearance of extracellular Aβ. Hence, accumulation of Aβ peptide participates to the pathological condition of AD, while inhibiting Aβ production or increasing Aβ removal may be implicated in slowing the improvement of AD. In particular, the promotion of Aβ clearance is currently considered to be an additional therapeutic approach for AD. Thereby, autophagy has been found to be an important role in the clearance of Aβ under physiological conditions, for that reason it is essential to maintain Aβ homeostasis in the healthy brain. Most importantly, our current research is considerable effort directed to identify safe and more effective pharmacological inducers of autophagy in neurodegenerative diseases. Therefore, enhancement of autophagy might represent a sustainable strategy to Aβ clearance.

Even though a variety of autophagy-related proteins participate and control in autophagy pathway, several studies have been performed to explore autophagy regulation through the active ingredients of plants. Although numerous fundamental queries are essential to be further addressed before many novel agents could be useful in a clinical approaches, thus the research of interest in autophagy is developing rapidly and clinically applicable might be anticipated as soon as possible. Furthermore, it is very important to characterize dysfunctional autophagy in diverse stages of genetic and molecular subtypes in neurodegeneration. It is also necessary to study the active clinical translation of downstream autophagy regulation which proposes an exciting new era for the development of therapeutic strategies. Consequently, additional studies are required on physiological roles of modulation of brain autophagy process in neurodegenerative diseases. Finally, we would like to screen new natural compounds that modulate autophagy and identify main targets key molecular mechanisms underlying pathophysiological roles of neurodegeneration with concern for potential therapeutic drugs target.

The Mistaken Belief that Rejuvenation Therapies Will Not Arrive in our Lifetimes

If you ask those who are skeptical, disinterested, or even hostile towards work on the basis for rejuvenation therapies, many of them justify their positions with - among other items - a belief that rejuvenation is a far future possibility, not something that will arrive in their lifetimes. So why should they offer their support, given that they will not benefit? They'd rather leave it to the slow march of science, which most people seem to think just happens, a background process that runs without any outside intervention.

Firstly, this is a dramatically mistaken point of view. The first of the SENS-style rejuvenation therapies, the clearance of senescent cells, is presently in the clinical development pipeline in a number of startup companies. Forms of treatment will be available a few years from now via medical tourism, and the adventurous can already obtain many of the candidate drugs and try their own self-experimentation. The first class of rejuvenation therapy is imminent, not distant.

Secondly, even if it were true that rejuvenation is long way distant, why not help to build the infrastructure for a better world that will carry forward into a future that you expect not to be around for? People do that all the time in other parts of their lives, without the same sort of vocal rejection that all too frequently accompanies views on healthy life extension, a goal to be achieved through new medicine to treat the causes of aging. Why should longevity be any different? I think that this is another of the many ways in which people demonstrate a strange irrationality when it comes to aging and medicine.

This is what I call a 'meta-objection', because it's not really meant against rejuvenation per se. Rather, this meta-objection is usually raised after a long, drawn-out conversation between a rejuvenation advocate and an opposer. At the end of the debate, when the suspicion that rejuvenation is in fact desirable and may be feasible is starting to creep up into the opponent's mind, they resort to their final, desperate line of defence, the very last stronghold behind which their cognitive ease can still find shelter. If we all thought like that, no one would do anything to make rejuvenation happen, and consequently it would never happen, in anyone's lifetime, ever. We can either risk it and do all that is in our power to make rejuvenation happen sooner rather than later, or we can sit about and wait to become old and sick.

Besides, if rejuvenation is worthy goal per se, should you not help pursue it just because you might not reap the benefits? We hear all the time that we should take good care of the planet for the sake of future generations and be concerned about the kind of world we leave them with. Well, we can try to leave them with a world where ageing has been cured, so that those very future generations we seem to care so deeply about won't have to go through the plague of age-related diseases. If you have children, this should resonate particularly well with you. Old or young, they'll always be your children, and you'll always care for them, right? Without rejuvenation, they too will be condemned to decades of infirmity and suffering, and ultimately to an unnecessary death.

If rejuvenation could be achievable within the opposer's lifetime, they would have a glimmer of hope to hang on. And as they say, isn't it hope that kills us all? If they decided to accept this possibility, it would mean a lot of mental work, of the kind people generally dislike. First, there's the risk of disappointment. What if something went wrong, and rejuvenation didn't come in time for the opposer? They'd have spent a life hoping for something that never came. The thought isn't particularly nice. Second, there's a choice to be made between activism and 'inactivism'. In order for rejuvenation to become real, there's a lot of work to be done, not only in terms of research but also advocacy. Would the opposer be willing to do their part and spread the word, convince others of the worthiness of the cause, and take action to make it happen sooner? That's a lot of work, and there's no guarantee of success. They'd have to endure endless debates with sceptics, which could be quite taxing.

This is not all! Accepting the possibility that rejuvenation may become a thing within their own life, and that they may actually want it for themselves, the opposer is forced to seriously question their previous assumptions on ageing. This idea that ageing is bad for you and not desirable is a new thing, one they're not used to. They're used to accepting ageing, to think of it as a blessing that prevents the (imaginary) risks of eternal boredom, overpopulation, everliving tyrants, and a series of other sensible-sounding, but ultimately groundless excuses we've made up throughout history to cope with the sad truth of the grim descent into frailty, disability, and disease that precedes death. If they challenged their old assumptions on ageing, the opposer would be forced to conclude that ageing is a really bad thing - and what's worse, that really bad thing is coming for them, and their chances to avoid it are tied to a technology that may or may not come into existence depending not only on the progress of science, but also largely on how willing other opposers will be to challenge their own preconceptions on ageing.

This is where our opposer comes to the realisation that he or she would have to deal with all this trouble only if rejuvenation could happen within their own lifetime. If rejuvenation was so far into the future that the opposer was granted to die before they could ever benefit from it, all of these troubles would just disappear. 'Yes,' the opposer would say, 'maybe defeating ageing is feasible and perhaps even desirable, but it's not doable within my lifetime. So, there's no need to concern myself with it.' It's so easy, isn't it? The easiest way of 'solving' a problem is pretending it isn't there to begin with. You can keep repeating to yourself all the lies about why ageing would be a good thing, until - as it's often the case - they start to feel true and make you feel good.

Link: https://rejuvenaction.wordpress.com/answers-to-objections/objections-to-rejuvenation/rejuvenation-wont-happen-within-my-lifetime/

Cannabinoid Metabolism and Age-Related Memory Decline

Researchers here demonstrate a role for cannaboids in the age-related decline of memory function. Levels of natural cannaboids decline with aging, and the researchers provide evidence for this to be a proximate cause of the loss of memory function in later life. They also show that it is possible to stave off this decline in laboratory mice by using low doses of tetrahydrocannabinol (THC) to supplement natural cannaboids:

Like any other organ, our brain ages. As a result, cognitive ability also decreases with increasing age. This can be noticed, for instance, in that it becomes more difficult to learn new things or devote attention to several things at the same time. This process is normal, but can also promote dementia. Researchers have long been looking for ways to slow down or even reverse this process and have now achieved this in mice. These animals have a relatively short life expectancy in nature and display pronounced cognitive deficits even at twelve months of age. The researchers administered a small quantity of THC, the active ingredient in the hemp plant (cannabis), to mice aged two, twelve and 18 months over a period of four weeks. Afterwards, they tested learning capacity and memory performance in the animals - including, for instance, orientation skills and the recognition of other mice. Mice who were only given a placebo displayed natural age-dependent learning and memory losses. In contrast, the cognitive functions of the animals treated with cannabis were just as good as the two-month-old control animals. "The treatment completely reversed the loss of performance in the old animals."

This treatment success is the result of years of meticulous research. First of all, the scientists discovered that the brain ages much faster when mice do not possess any functional receptors for THC. These cannabinoid 1 (CB1) receptors are proteins to which the substances dock and thus trigger a signal chain. CB1 is also the reason for the intoxicating effect of THC in cannabis products, which accumulate at the receptor. THC imitates the effect of cannabinoids produced naturally in the body, which fulfill important functions in the brain. "With increasing age, the quantity of the cannabinoids naturally formed in the brain reduces. When the activity of the cannabinoid system declines, we find rapid ageing in the brain."

To discover precisely what effect the THC treatment has in old mice, the researchers examined the brain tissue and gene activity of the treated mice. The findings were surprising: the molecular signature no longer corresponded to that of old animals, but was instead very similar to that of young animals. The number of links between the nerve cells in the brain also increased again, which is an important prerequisite for learning ability. A low dose of the administered THC was chosen so that there was no intoxicating effect in the mice. Cannabis products are already permitted as medications, for instance as pain relief. As a next step, the researchers want to conduct a clinical trial to investigate whether THC also reverses ageing processes in the brain in humans and can increase cognitive ability.

Link: https://www.uni-bonn.de/news/128-2017

Fight Aging! Invests in the Methuselah Fund

As you might recall, the Methuselah Foundation recently formalized its years of non-profit activities as an incubator of biotechnology startups to launch the Methuselah Fund. The goal remains the same: to accelerate the development of rejuvenation biotechnology by funding promising young companies in important areas of medicine. That has included Organovo, now a publicly traded bioprinting company whose founders have helped the New Organ initiative, and Oisin Biotechnology, where the founders are developing a gene therapy approach to the selective destruction of senescent cells. Not resting on their laurels, the Methuselah Foundation volunteers are presently shepherding the early stages of Leucadia Therapeutics and its work on a novel approach to an Alzheimer's therapy.

I'm pleased to say that Fight Aging! has taken the plunge to make a mixed philanthropic and for-profit investment in the Methuselah Fund, alongside a number of other people in our community. This is a continuation of past charitable support of the Methuselah Foundation and modest investments made over the past year and a half in a few of the emerging startups relevant to rejuvenation biotechnology. In this case it is a fund, not a company, so it is in effect a somewhat more diversified form of support that will be split between the companies that the Methuselah Fund staff choose to support over the years ahead. It is an investment in the positive impact on the future of our health and longevity that I believe the Methuselah Foundation team can produce if given greater amounts of funding and let loose on the field.

It is sad economic reality that there is an order of magnitude more funding out there ready to invest in high-risk for-profit categories, such as startup companies, than there is available for charitable non-profit funding of research. There is yet another order of magnitude greater funding available for investment in later, less risky stages of for-profit development. Yet progress in technology depends on fundamental research, and all of the new biotechnologies needed to create working rejuvenation therapies require non-profit research funding in order to come to fruition. Research funding is the limiting factor on the pace of progress. So in effect there is a lot of for-profit funding sitting on the sidelines, waiting for the comparatively tiny amount of available research funding to produce results that can be commercialized. It seems inefficient to me, but it is what it is. Look at your own net worth and choices for the future: how much can you realistically allocate to non-profit donations versus for-profit investments that align with your values and visions? You have to be either significantly more wealthy or significantly more of a zealot than I for the former figure to be larger than the latter.

Which is not to even talk about the fact that funding for aging research and in particular for rejuvenation biotechnology is tiny in the grand scheme of things, even considering the above points. In the bigger picture, in which our community is creating an industry, warming up to sufficient funding for effective development of repair therapies for the damage of aging, we're only just getting started. Best foot forward, and the world is just now starting to wake up given the noise being made about clearance of senescent cells. The next few years will be interesting indeed as we reach a series of important tipping points, but tipping points or not, I don't see it ceasing to be a challenge to raise the funds needed, either for the research or for the companies that result from that research. We just getting better at it, and more sources of funding are potentially open to participation.

Still, there are concrete reasons as to why I support the Methuselah Foundation and now the Methuselah Fund. The best sort of investment fund for our field is one that doesn't just sit around waiting for scientists and entrepreneurs to figure out their own way to building the technology, starting a company, and come knocking in search of seed funding. The best sort of organization is one that reaches down into the research community and helps to bring at least some the best lines of research to the point at which commercial development is possible. For the past fifteen years that has been the Methuselah Foundation, coming at this challenge from the non-profit direction. It is a model that is now being adopted by newer groups such as the Forever Healthy Foundation, coming at the challenge from the venture funding direction.

The longevity community needs more organizations like these that straddle the divide between non-profit funding of promising research on the one hand, and funding of the companies that are created as a result of that research on the other hand. It isn't enough just to get the research into a promising state of readiness. Why stop there, where there is plenty still left to achieve in order to reach the clinic? It isn't enough just to fund the companies that emerge. Why be stuck waiting for those companies when you could achieve so much more by supporting and guiding the most promising research groups prior to that stage?

Prevention of Stroke and Prevention of Dementia Overlap

Aging is a process in which a smaller number of mechanisms produce a larger range of consequences. This is true at the start of the chain of cause and effect, in which cell and tissue damage outlined in the SENS rejuvenation research programs produces a large range of secondary dysfunctions. It is also true further along the chain, where researchers observe diverse age-related diseases to share overlapping sets of common proximate causes. You might consider aging as a spreading tree of problems, the number of possible classes of dysfunction expanding dramatically at each layer of cause and effect.

This is characteristic of any simple cause of damage operating in a complex system - think of rust in an ornate metal structure standing upon many legs, for example. It might ultimately fall apart in any number of ways, but rust is a very simple process. It is far easier to handle the rust than to try to prop things up in other ways while letting the rust continue to progress. So too with aging: the easiest and most cost-effective way forward is to target and repair the root causes of aging, not the later problems. The further along the chain of consequences, the more complex the picture and the less effective the solutions. Still, any attempt to reduce the impact at any stage should produce benefits to more than one measure of aging or age-related disease, as illustrated here:

A stroke prevention strategy appears to be having an unexpected, beneficial side effect: a reduction also in the incidence of dementia among older seniors. A new paper shows there's been a decade-long drop in new diagnoses of both stroke and dementia in the most at-risk group ­­- those who are 80 or older. "Some have said we're on the cusp of an epidemic of dementia as the population ages. What this data suggests is that by successfully fighting off the risks of stroke - with a healthy diet, exercise, a tobacco-free life and high blood-pressure medication where needed - we can also curtail the incidence of some dementias."

This is the first study that has looked at the demographics of both stroke and dementia across Ontario since the province pioneered Canada's first stroke prevention strategy in 2000. That strategy includes more health centres able to manage stroke, more community and physician supports, better use of hypertensive mediation and well-promoted lifestyle changes to reduce risks. Five provinces have stroke strategies and five do not. "We have systems in place for stroke prevention and our hypothesis is that any studies looking at stroke prevention should also investigate dementia prevention. It's a good-news story for Ontario and it could be a good-news story elsewhere."

Most strokes are caused by the restriction or constriction of blood flow to the brain. Vascular dementia also develops as blood supply to the brain is reduced. Someone who has had a stroke is twice as likely to develop dementia. Someone who has had a diagnosis of stroke has also likely had several prior "silent" strokes that may have affected a patient's cognitive abilities. Specifically, the study data shows that the incidence of new stroke diagnosis among highest-risk group, people aged 80-plus, dropped by 37.9 per cent in a span of a little more than a decade. During the same timeframe, the incidence of dementia diagnoses in that age group fell by 15.4 per cent. "As clinicians and researchers, we are still trying to get a handle on how to reduce a person's chances of dementia late in life. Some we can't influence - yet - but here is a pretty clear indication that we can take specific definitive steps to reduce our chances of dementia related to vascular disease."

Link: http://mediarelations.uwo.ca/2017/05/01/stroke-prevention-among-older-ontarians-may-also-reduce-risk-dementias/

Towards a Soft Synthetic Retina

Researchers have made the first steps towards generating a soft synthetic replacement for the retina that is capable of generating electrical signals in response to light. A great deal of work is yet to be accomplished in order to turn this initial proof of concept into an implant that can restore some form of light-sensitivity and sight to an individual with a damaged retina, but it is an interesting alternative to the electrode grid approach that has taken off in recent years. Initial practical models will likely work in a similar fashion, producing phosphenes in a pattern that corresponds to the shading of the current field of view rather than true sight, but a continuous soft medium should be capable of greater detail and contrast than an electrode grid, at least in principle.

Until now, all artificial retinal research has used only rigid, hard materials. The new research is the first to successfully use biological, synthetic tissues, developed in a laboratory environment. The study could revolutionise the bionic implant industry and the development of new, less invasive technologies that more closely resemble human body tissues, helping to treat degenerative eye conditions such as retinitis pigmentosa. Just as photography depends on camera pixels reacting to light, vision relies on the retina performing the same function. The retina sits at the back of the human eye, and contains protein cells that convert light into electrical signals that travel through the nervous system, triggering a response from the brain, ultimately building a picture of the scene being viewed.

Researchers developed a new synthetic, double layered retina which closely mimics the natural human retinal process. The retina replica consists of soft water droplets (hydrogels) and biological cell membrane proteins. Designed like a camera, the cells act as pixels, detecting and reacting to light to create a grey scale image. "The synthetic material can generate electrical signals, which stimulate the neurons at the back of our eye just like the original retina." Unlike existing artificial retinal implants, the cell-cultures are created from natural, biodegradable materials and do not contain foreign bodies or living entities. In this way the implant is less invasive than a mechanical device, and is less likely to have an adverse reaction on the body. At present the synthetic retina has only been tested in laboratory conditions, but the researchers are keen to build on the initial work and explore potential uses with living tissues. The next phase of the work will see the team expand the replica's function. Working with a much larger replica, the team will test the material's ability to recognise different colours and potentially even shapes and symbols.

Link: http://www.ox.ac.uk/news/2017-05-04-oxford-student-creates-first-synthetic-retina

National Eye Institute Launches the 3-D Retina Organoid Challenge

I notice that the National Eye Institute (NEI) is launching a tissue engineering challenge of the sort pioneered by the Methuselah Foundation in recent years. You might recall the New Organ initiative and the various related research prizes offered for important advances in the generation of patient-matched organs to order. Since the Methuselah Foundation staff have been taking the approach of partnering with government bodies where possible, as in the case of NASA and the Vascular Tissue Challenge, I imagine they will be pleased to see other groups following their lead. The past ten to fifteen years of various research prizes and challenges have hopefully established this approach as a viable and useful addition to the more usual methods of allocating funds for research and development. Most of the data suggests it is highly efficient in terms of attracting investment, and can help to accelerate growth and interest in specific areas of research.

When it comes to tissue engineering the National Eye Institute is, as you might imagine, interested in structures within the eyes. They wish to promote greater efforts in the production of viable, working retinal tissue. At the moment, given the present limitations on the generation of blood vessel networks, all such functional tissue takes the form of small sections called organoids, perhaps a few millimeters in each dimension. Nutrients must reach cells by diffusion in the absence of capillaries, so the tissue cannot be much larger than this. The recipe for generating an organoid - the cell types, environment, timing, and molecular signals needed - is different for each form of tissue, and there are a lot of different forms of tissue in the human body. Thus a great many researchers are occupied in discovering the recipes needed for those tissues most of interest in medicine and research, and outside that list there is still a large number of projects awaiting someone with the time, funding, and knowledge needed to make progress.

The production of organoids is a valuable undertaking. It is a stepping stone towards the construction of full organs in the sense that (a) organoids can help to make research faster and more cost-efficient in many areas of medicine, (b) the recipe for their production will be needed in order to build complete organs as and when the blood vessel network problem is solved, and (c) in a few cases, for organs that are essentially chemical factories and for which shape and location are not so important, organoids might already be the basis for useful transplant therapies. This last item is probably not going to be the case for retinal organoids, but you never know.

NIH launches competition to develop human eye tissue in a dish

The National Eye Institute (NEI), part of the National Institutes of Health, has opened the first stage of a federal prize competition designed to generate miniature, lab-grown human retinas. The retina is the light- sensitive tissue in the back of the eye. Over the next three years pending availability of funds, NEI plans to offer more than $1 million in prize money to spur development of human retina organoids. "None of the model systems currently available to researchers match the complex architecture and functionality of the human retina. We are looking for new ideas to create standardized, reproducible 3-D retina organoids that can speed the discovery of treatments for diseases such as age-related macular degeneration and diabetic eye disease, both leading causes of blindness."

Research models are more valuable the more closely they mimic human tissue. Researchers hope to use retina organoids to study how retinal cells interact under healthy and diseased conditions, and to test potential therapies. The ideation stage of the 3-D Retina Organoid Challenge aims to generate innovative ideas that can later be turned into concrete concepts. Running until August 1, 2017, the total prize purse for the ideation stage is $100,000. "We're looking for creative insights and application of new technology to unleash the full potential of retinal organoids. Our goal is for researchers to be able to generate or obtain retinal organoids easily so that they can be widely used for understanding diseases and testing drugs. To do this, we are encouraging entries from diverse teams of participants."

The development stage of the challenge will require demonstration of a functional retina organoid prototype. This stage is planned to launch in fall 2017 and expected to offer $1 million in prize money. Full details of the 3-D Retina Organoid Challenge prize competition are available online.

Simple Arterial Health Measures as a Basis for a Biomarker of Aging

As regular readers will know, the development of a robust and cost-effective biomarker of biological age is important. At present the only way to assess the effects of a potential rejuvenation treatment on remaining life expectancy is to wait and see; that makes animal studies very slow and expensive, and human studies impractical. To speed up research, the scientific community needs a generally agreed upon assessment that can run shortly before and shortly after the application of a therapy, and that provides a good measure of biological age - of the present load of cell and tissue damage and its consequences. Here, researchers propose a largely cost-effectiveness argument for using arterial health metrics as a basis for such a biomarker. This might be good for some types of rejuvenation therapy, but it isn't hard to envisage classes of treatment that either preferentially impact the vascular system, or do little to help in that tissue. This is a challenge for any potential biomarker of aging that derives from tissue- or organ-specific measures.

Measuring aging biologically rather than chronologically provides a personalized view to an optimal, rather than "normal" or "typical" health. Throughout the course of life, each of us gradually departs from the health trajectory defined by our individual genome. Even in the case of identical twins, substantial differences in the timing of the onset development of particular aging-associated symptoms are commonplace. Hence, an adult individual's rate of ageing depends primarily on lifestyle rather than genes. The newly introduced concept of anti-aging interventions enables individuals to actively modify their lifestyles or pharmacologically correct for accumulating biochemical or functional deficits. In order to properly evaluate relative efficiency of these interactions, objective measures of attained ageing are necessary.

At best, biological age can be reflected by overall resemblance of an aged individual to an average degree of age-associated changes observed in a given population at given age. In the frame of this definition, any departure from population-wide standard of aging stems from a combination of environmental and genetic factors that either promote or delay the development and subsequent involution of various physiological systems and their capability to adapt. Therefore, a positive or a negative difference between biological and chronological age, observed in a given individual, may be interpreted as either speeding up or slowing down the ageing process, thus, providing a measure for an evaluation of one or another anti-ageing intervention.

There is a long history of attempts to determine biological age and quantify the tempo of the process of ageing. Typically, age determination utilizes one or another molecular facet of ageing, for example, the degree of the damage to cell's DNA. Among more recently developed integrative biomarkers of aging is the GlycanAge index that profiles the structural details of sugar chains attached to the conserved N-glycosylation sites of three types of IgG molecules. This index reflects the level of systemic inflammation, predicts chronological age with standard deviation of 9.7 years, and is superior to age evaluation using telomere length. Peripheral blood mononuclear cells (PBMCs) mRNAs-based "transcriptome age" index predicts chronological age with mean absolute error of 7.8 years. Even more precise PBMCs-based "epigenetic age" relies the methylation of three CpG sites located in ITGA2B, ASPA and PDE4C genes with standard deviation of less than 5 years. An increase in the number of profiled CpG dinucleotides to 353 improves epigenetics-based age estimates by decreasing an error down to 2.9 years.

It should be noted that all the techniques described above require specialized equipment and skilled laboratory personnel, thus, limiting their clinical applicability. On another end of the spectrum are age-predicting models not specifically connected to any particular mechanism of aging, for example, deep neural networks (DNNs) modules evaluating common blood biochemistry and cell count tests. Though the accuracy of this model is quite high, the number of parameters in the model is also high. Since deep neural nets are, in a nutshell, "black boxes", the dissection of these models into mechanistic insights into the process of ageing is impossible. The majority of the techniques described above have not yet entered clinical practice. The major culprits causing this lack of translation to the clinic have been a high number of the parameters requiring evaluation, and the laboratory rather than clinical nature of tests being performed. From a clinical perspective, the most convenient estimate of biological age would be the one relying on a combination of biochemical and physiological parameters typically evaluated in course of annual physical exam.

In this study, we attempt the dissection of biochemical and clinical predictors of age, the development of a predictive model for biological age, and exploration of the deviation of these predictions from chronological age in a cohort of 303 individuals. We quantified 89 clinical and biochemical parameters, then selected the top five parameters with a highest Pearson's correlation with chronological age. Importantly, all five of these parameters reflect the functioning of the cardiovascular system. The outputs of the gender-specific linear regression models predicting chronological age were compared to actual age of the subjects. Substantially higher differences between the predicted age and the calendar age were noted for patients with Type 2 Diabetes Mellitus (T2D) as compared to non-T2D controls. We believe that the proposed gender-specific models, which we named Male and Female Arterial Indices, may serve as a good approximation for an elusive biological age. Importantly, the proposed age-approximation techniques rely on functional tests which do not require specialized laboratory equipment and, therefore, could be performed in hospitals and community healthcare settings.

Link: http://dx.doi.org/10.18632/aging.101227

Oxidative Stress Caused by Immune Cells Contributes to the Age-Related Decline in Liver Regenerative Capacity

Researchers here provide evidence for the age-related decline in regenerative capacity of the liver to be caused in part by oxidative stress produced by innate immune cells. This makes the adult stem cells responsible for tissue maintenance less likely to activate, but when removed from the tissue environment the cells appear more or less as capable as those of younger individuals. In some other tissues, such as muscle, where stem cell biology is better studied, it is also thought that changes in the surrounding environment rather than internal damage drives the majority of the decline in stem cell activity with aging. This means that therapies capable of activating stem cells in older individuals may prove to be less risky and more useful than would otherwise be the case.

Like all the other organs, there are structural and functional changes in the liver during aging, including diminished functions. Notably, a decrease in regenerative capacity in aging liver has been observed in old patients who had severe viral and toxic injury. In addition, studies on liver transplantation in human patients showed lower graft and recipient survival if the donor was in advanced age. Similar results were also observed after liver transplantation in rats. Therefore, investigating the mechanisms of declined regeneration in liver is critical to understand age-associated hepatic pathologies and diseases.

Decreased tissue regeneration and homeostasis are frequently associated with impaired stem cell function, implicating alterations of stem cells within tissues and organs during aging. As recently reported, aging-associated phenotypical and functional variations have been observed for adult stem cells or progenitor cells in various tissues, including epidermis, muscle, blood and brain. Age-related decrements in stem-cell functionality may occur at different levels, including cell-autonomous dysfunction, altered niche where stem cells reside, systemic milieu and the external environment. Liver is an organ with low turnover in homeostasis, but high regenerative capacity under acute injury. However, little is known about the changes of stem cells within liver responsible for liver regeneration upon liver injury during aging.

Liver progenitor cells (LPCs), also known as 'oval cells', are a stem cell population within the liver. Upon massive liver injury, LPCs may be activated. LPC expansion occurs in many human liver diseases and experimental animal models, and treatment with LPCs could prevent liver injury in rodents. Therefore, LPCs play an important role in maintaining the homeostasis and regeneration of the liver. Characterizing biological properties LPCs during aging will be important to gain insight into age-associated liver pathologies and disease.

According to the 'free-radical theory' of aging, endogenous oxidants could be generated in cells and resulted in cumulative damage. Those oxidants, free reactive oxygen species (ROS), are specific signaling molecules regulating biological processes under both physiological and pathophysiological conditions. Within a certain extent, the generation of ROS is essential to the maintenance of cellular homeostasis. However, excessive generation of ROS might lead to the damage of various cell components and the activation of specific signaling pathways, which will influence aging and the development of age-related diseases. Neutrophils can be recruited by a variety of cytokines or signals. Neutrophil-derived ROS are generated during the process of respiratory burst and are important for neutrophil bactericidal activity. Previous studies have found that spontaneous ROS production from neutrophils may increase with age and represent the different aspect of age-associated immune dysregulation.

Our findings demonstrate that liver regeneration and LPC activation are negatively regulated during aging. Impairment of liver regeneration in old mice might not be resulted from intrinsic changes of LPCs, but from changes of the stem cell niche including neutrophils and hepatic stellate cells. Based on our findings, we propose the following model. In old mice, upon induced liver injury, hepatic stellate cells produce CXCL7 to recruit neutrophils into liver. After neutrophils infiltrate into liver, they are activated and a neutrophil oxidative burst is induced. Then, neutrophil-derived excessive oxidative stress induces DNA double strand damage in LPCs and restricts LPC proliferation, leading to the impairment of liver regeneration. Our findings establish a mechanistic link between LPCs and the stem cell niche including neutrophils and hepatic stellate cells, during liver regeneration in old mice.

Link: http://dx.doi.org/10.18632/aging.101232

Follow the Example of Aubrey de Grey: In the Matter of Aging, Aim High

When it comes to evading the consequences of aging - frailty, pain, and death - our ancestors could aim as high as they liked, and it would have made no difference. The knowledge and technology of their eras could do little but somewhat slow aging, or somewhat reduce the suffering inherent in the last years of life. So, aside from the few in each generation who overestimated the bounds of the possible or deluded themselves in worse ways, they stopped aiming high. The state of the art in the human approach to aging came to be a collection of ways to avoid despair, to accept what is rather than attempt to change it, some of which are very useful indeed within that narrow scope. Stoicism, for example, is an outstanding example of thought applied to thought, an illustration of one of the ways in which philosophy can have practical outcomes, if approached in the right way.

The past is the past, however. The age in which nothing could be done about aging is over. The visionary few are now right, and the stoic many are now wrong. Rejuvenation therapies based on repair of the root causes of aging are on the horizon, and the first of them are presently in clinical development. Stocism in the face of the inevitable, for so long the rational approach to aging, is now irrational. All of the mental apparatus assembled to deal with the certainty of decline is obsolete and harmful. Coming to terms with aging is self-sabotage, a slow form of suicide on the eve of working rejuvenation treatments. Aiming high, aiming to bring aging under medical control, is the right course of action for our era. It is the way to save the most lives, to prevent the most suffering, to bring the greatest benefit to the most people.

Scientists are waging a war against human aging. But what happens next?

We all grow old. We all die. For Aubrey de Grey, a biogerontologist and chief science officer of the SENS Research Foundation, accepting these truths is, well, not good enough. He decided in his late twenties (he's currently 54) that he "wanted to make a difference to humanity" and that battling age was the best way to do it. His life's work is now a struggle against physics and biology, the twin collaborators in bodily decay. He calls it a "war on age." de Grey considers aging an engineering problem. The human body is a machine, he told me in the following interview, and like any machine, it can be maintained for as long as we want. This is not an isolated view. There is a broader anti-aging movement afoot, which seems to be growing every day.

de Grey's work is particularly interesting. For too long, he argues, scientists have been looking for solutions in all the wrong places. There is no monocausal explanation for aging. We age because the many physical systems that make up our body begin to fail at the same time and in mutually detrimental ways. So he's developed what he calls a "divide-and-conquer strategy," isolating the seven known causes of aging and tackling them individually. Whether it's cell loss or corrosive mitochondrial mutations, de Grey believes each problem is essentially mechanical, and can therefore be solved.

Sean Illing: Is there a simple way to describe theoretically what the anti-aging therapies you're working on will look like - what they'll do to or for the body?

Aubrey de Grey: Oh, much more than theoretically. The only reason why this whole approach has legs is because 15 or 17 or so years ago, I was actually able to go out and enumerate and classify the types of damage. We've been studying it for a long time, so when I started out in this field in the mid-'90s so I could learn about things, I was gratified to see that actually aging was pretty well understood. Scientists love to say that aging is not well understood because the purpose of scientists is to find things, out so they have to constantly tell people that nothing is understood, but it's actually bullshit. The fact is, aging is pretty well understood, and the best of it is that not only can we enumerate the various types of damage the body does to itself throughout our lives, we can also categorize them, classify them into a variable number of categories. We know how people age; we understand the mechanics of it. More importantly, for each category there is a generic approach to fixing it, to actually performing the maintenance approach that I'm describing, repairing the damage.

Sean Illing: Can you give me an example of one of these categories and what the approach to fixing it looks like?

Aubrey de Grey: One example is cell loss. Cell loss simply means cells dying and not being automatically replaced by the division of other cells, so that happens progressively in a few tissues in the body and it definitely drives certain aspects of aging. Let's take Parkinson's disease. That's driven by the progressive loss of a particular type of neuron, the dopaminergic neuron, in a particular part of the brain. And what's the generic fix for cell loss? Obviously it's stem cell therapy. That's what we do. We preprogram cells in the laboratory into a state where you can inject them into the body and they will divide and differentiate to replace themselves that the body is not replacing on its own. And stem cell therapy for Parkinson's disease is looking very promising right now.

Sean Illing: Is it best to think of aging as a kind of engineering problem that can be reversed or stalled? You're not trying to solve the problem of death or even aging, really. It's more about undoing the damage associated with aging.

Aubrey de Grey: Absolutely. It's a part of technology. The whole of medicine is a branch of technology. It's a way of manipulating what would otherwise happen, so this is just one part of medicine. Certainly the goal is to undo the damage that accumulates during life, and whether you call that "solving aging" is up to you.

Sean Illing: What do you say to those who see this as a quixotic quest for immortality, just the latest example of humanity trying to transcend its condition?

Aubrey de Grey: Sympathy, mainly. I understand it takes a certain amount of guts to aim high, to actually try to do things that nobody can do, that nobody's done before. Especially things that people have been trying to do for a long time. I understand most people don't have that kind of courage, and I don't hate them for that. I pity them. Of course, the problem is that they do get in my way, because I need to bring money in the door and actually get all this done. Luckily, there are some people out there who do have courage and money, and so we're making progress.

Sean Illing: Are there any ethical questions or reservations that give you pause at all?

Aubrey de Grey: Not at all. Once one comes to the realization that this is just medicine, then one can address the entire universe of potential so-called ethical objections in one go. Are you in favor of medicine or not? In order to have any so-called ethical objection to the work we do, the position that one has to take is the position that medicine for the elderly is only a good thing so long as it doesn't work very well, and that's a position no one wants to take.

Sean Illing: When will the therapies you're developing be ready for human experimentation?

Aubrey de Grey: That will happen incrementally over the next 20 years. Each component of the SENS panel will have standalone value in addressing one or another disease of old age, and some of them are already in clinical trials. Some of them are a lot harder, and the full benefit will only be seen when we can combine them all, which is a long way out.

The future of rejuvenation is only as certain as the work directed to bring it about. Once any particular technology reaches a critical mass of support within the research and development communities, then it becomes an avalanche, as is happening today for senescent cell clearance in the form of varied senolytic therapies as a method of rejuvenation. But pushing the most promising technologies to that point requires a great deal of advocacy, funding, and effort - all too many lines of research that are just as promising as senolytics still languish in comparative obscurity. Aubrey de Grey, the Methuselah Foundation, and SENS Research Foundation advocated senescent cell clearance for more than 15 years, but only in the past few years has this finally gone somewhere. It is a tough business to be in, changing the minds of the world, but the advocates were right: right to aim high, and right about the fundamental reasons for picking senescent cell clearance as an approach, based on a guiding philosophy of repair of cell and tissue damage. The mainstream research community that rejected senolytic approaches until recently was wrong: wrong to aim at the lesser target of modestly slowing aging, and wrong for choosing the guiding philosophy of altering metabolism in order to slow down the rate at which cell and tissue damage accumulates.

Research at the cutting edge depends absolutely upon philanthropy. Within the present very conservative establishment of research funding, truly novel projects simply don't get funded: there is only funding for later stages of development, once risks have been reduced and consensus exists across large portions of the research community. Prior to that, in the small and vital space where new ideas and new science happen, there is next to no support. This is why it is hard for individual career researchers to break through and aim high. But where the research community and its supporters do not aim high, they fail to achieve results such as the current brace of senolytic therapies under development, an approach with a demonstrated ability to reverse measures of aging in laboratory animals. If you look at the SENS Research Foundation portfolio of rejuvenation research, a portfolio that has long included clearance of senescent cells, the majority of it has only progressed to the degree that individual visionary patrons - including many in the audience here - have been willing to fund it over the years. It has been slow and frustrating, but the wheel is turning. The success accomplished for the field of cellular senescence must now be repeated for a half dozen other vital lines of rejuvenation biotechnology. Aim high.

Mitochondria-Derived Damage-Associated Molecular Patterns in Aging

Mitochondria-derived damage-associated molecular patterns (DAMPs) are a proposed link between age-related mitochondrial damage and age-related inflammation, and this open access paper outlines present thinking on the topic. Mitochondria, the power plants of the cell, are strongly implicated in the progression of aging in a number of ways, the SENS view of damage to mitochondrial DNA producing dysfunctional cells being one, and a more general decline in mitochondrial energy generation for other reasons, yet to be fully mapped, being another. DAMPs are more in line with the first view rather than the second, in which broken cells and their mitochondria generate signals and other molecules that are either directly or indirectly causing further damage. Increased chronic inflammation might be considered a form of damage; it drives faster progression of all of the common age-related conditions, and any dysfunction that produces chronic inflammation is in effect a contributing cause of aging.

Aging is a complex and multi-factorial process characterized by increased risk of adverse health outcomes. Understanding the intimate mechanisms of aging is therefore instrumental for contrasting its negative correlates. As initially proposed in the "mitochondrial theory of aging", mitochondria are deeply involved in the aging process mainly through respiratory dysfunction and oxidant generation. Although unique as fueling systems within the cell, mitochondria participate in other essential functions, including heme metabolism, regulation of intracellular calcium homeostasis, modulation of cell proliferation, and integration of apoptotic signaling. It is therefore crucial that a pool of healthy and well-functioning organelles is maintained within the cell. To this aim, a comprehensive set of adaptive quality control processes operates via interrelated systems, including pathways pertaining to protein folding and degradation, mitochondrial biogenesis, dynamics, and autophagy (mitophagy). The activation of individual mitochondrial quality control (MQC) pathways depends on the degree of mitochondrial damage. Due to these vital responsibilities, disruption of the MQC axis is invoked as a major pathogenic mechanism in a number of disease conditions.

Together with mitochondrial dysfunction, chronic inflammation is another hallmark of both aging and degenerative diseases. Interestingly, emerging evidence suggests that the two phenomena are related to one another. In particular, circulating cell-free mitochondrial DNA (mtDNA), one of the cell damage-associated molecular patterns (DAMPs), has been proposed as a functional link between mitochondrial damage and systemic inflammation. Indeed, mtDNA, which is released as a result of cellular stress, contains hypomethylated CpG motifs resembling those of bacterial DNA and is therefore able to induce an inflammatory response. These regions bind and activate membrane or cytoplasmic pattern recognition receptors (PRRs), such as the Toll-like receptor (TLR), the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR), and the cytosolic cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) DNA sensing system-mediated pathways. The mechanisms responsible for the generation of mitochondrial DAMPs as well as their contribution to the inflammatory milieu that characterizes aging and its associated conditions are not completely understood.

Population aging poses a tremendous burden on the society. This has instigated intense research on the mechanisms that make the elderly more susceptible to diseases and disability. Several processes have been identified. Among these, inflamm-aging, a condition of chronic inflammation that develops independent of infections, has gained special attention. The cellular mechanisms responsible for inflamm-aging are not fully understood. However, recent studies suggest that a danger cellular-driven response may represent a relevant player. The coexistence of oxidative stress resulting from mitochondrial dysfunction and sterile inflammation has been summarized in the concept of oxy-inflamm-aging that merges the role of inflammation and oxidative stress in the aging process. Specific "danger molecules" generated in an oxidative milieu have been proposed to contribute to inflamm-aging. From this perspective, aging may be envisioned as the result of an "autoimmune-like" process. Given the role played by mitochondrial DAMPs in the activation of sterile inflammation, the mechanisms favoring organelle damage, in particular failing MQC processes, represent a relevant matter to be addressed by future investigations.

Link: http://dx.doi.org/10.3390/ijms18050933

Researchers Construct Inner Ear Organoids

The research community has in recent years demonstrated the ability to grow fully or near fully functional organ tissue of many types from stem cells, and the research presented here adds a new type to the list. Tissue engineering of this sort is at present limited in size to very small tissue sections, called organoids, because researchers have yet to establish a reliable solution for integrating blood vessel networks into tissue built from the starting point of a few cells. Still, it is important work, as the recipes for various tissue types, all quite different in their details, are a necessary foundation for the next stage of organ engineering. That is expected to start up after blood vessel networks can be created efficiently and cheaply. The creation of organoids is also very useful for research here and now; a lot more can be done for a given amount of funding with organoids than with animal models.

Researchers at have successfully developed a method to grow inner ear tissue from human stem cells - a finding that could lead to new platforms to model disease and new therapies for the treatment of hearing and balance disorders. "The inner ear is only one of few organs with which biopsy is not performed and because of this, human inner ear tissues are scarce for research purposes. Dish-grown human inner ear tissues offer unprecedented opportunities to develop and test new therapies for various inner ear disorders."

The research builds on the team's previous work with a technique called three-dimensional culture, which involves incubating stem cells in a floating ball-shaped aggregate, unlike traditional cell culture in which cells grow in a flat layer on the surface of a culture dish. This allows for more complex interactions between cells, and creates an environment that is closer to what occurs in the body during development. By culturing human stem cells in this manner and treating them with specific signaling molecules, the investigators were able to guide cells through key processes involved in the development of the human inner ear. This resulted in what the scientists have termed inner ear "organoids," or three-dimensional structures containing sensory cells and supporting cells found in the inner ear.

"This is essentially a recipe for how to make human inner ears from stem cells. After tweaking our recipe for about a year, we were shocked to discover that we could make multiple inner ear organoids in each pea-sized cell aggregate." The researchers used CRISPR gene editing technology to engineer stem cells that produced fluorescently labeled inner ear sensory cells. Targeting the labeled cells for analysis, they revealed that their organoids contained a population of sensory cells that have the same functional signature as cells that detect gravity and motion in the human inner ear. "We also found neurons, like those that transmit signals from the ear to the brain, forming connections with sensory cells. This is an exciting feature of these organoids because both cell types are critical for proper hearing and balance."

Link: http://news.medicine.iu.edu/releases/2017/05/iu-researchers-inner-ear.shtml

Proposing Ketosis as an Important Component of Calorie Restriction

The practice of calorie restriction, reducing calorie intake by up to 40% while still obtaining optimal levels of micronutrients, is the most studied method by which aging can be slowed. Calorie restriction produces sweeping changes in the operation of metabolism, of which the most notable and relevant are probably the increased levels of cellular recycling and repair processes. Certainly, calorie restriction fails to slow aging in lineages where the cellular maintenance processes of autophagy are disabled, which is fairly compelling evidence for the benefits to primarily result from better maintenance of cells. Still, there are many other equally interesting lines of research and areas of biochemistry to explore in relation to lowered calorie intake. For example, sustained fasting appears to clear out malfunctioning immune cells to some modest degree. Intermittent fasting produces changes that are only similar to those of calorie restriction, not the same. Reducing the intake of proteins, and especially methionine, without reducing calorie intake again produces a similar outcome to calorie restriction, but one that is not exactly the same.

It is clear that the beneficial response to calorie restriction is far from simple: it may involve numerous distinct processes at root, and may have no one single point of control. This is interesting, given that calorie restriction is very well preserved throughout the tree of life. Widely diverse species ranging from yeasts to worms to mammals all have much the same beneficial response to lowered calorie intake, indicating that (a) it evolved very early in the development of cellular life, and (b) that slowing aging in the face of temporary famine confers such an advantage that this trait near always outcompetes the alternatives. The complexity of the calorie restriction response is unfortunate for those research groups seeking to recapture the benefits of calorie restriction through pharmaceutical means. A lot of time and funding has gone towards the development of calorie restriction mimetic drugs, and there is very little to show for those efforts beyond better maps of some of the biochemistry involved. Eating less remains the only reliable methodology.

The complexity of calorie restriction coupled with the current incomplete understanding of cellular metabolism also means that there is a lot of room for new research. It should not be surprising to read arguments for specific processes to be prioritized differently than is the case in the present understanding of what is going on under the hood in response to a low calorie diet. The research here is an example, in which the authors suggest that mechanisms underlying the well known state of ketosis are significant in the calorie restriction response, and thus ketosis is thus a potential avenue for the development of calorie restriction mimetics that might capture some of the beneficial outcomes of calorie restriction. I am agnostic on this point; the situation is complex enough that I'd want to see other researchers weighing in before taking it as read. This is one of those topics where putting it to one side and waiting a few years to see what results is probably the right thing to do. I'd certainly advocate avoiding anything written on the topic of ketosis that is not a part of a peer-reviewed research paper. There is a lot of misinformation and outright nonsense out there, powered by the diet industry in both its professional and amateur incarnations.

Ketone bodies mimic the life span extending properties of caloric restriction

Caloric or dietary restriction has been shown to increase life span in a wide variety of species. A number of proposed mechanisms for the phenomena have been suggested including: retardation of growth, decreased fat content, reduced inflammation, reduced oxidative damage, body temperature, and insulin signaling, and increase in physical activity and autophagy. However, no coherent mechanistic explanation has been generally accepted for this widely observed phenomenon that caloric restriction extends life span across the species. Yet, an obvious metabolic change associated with caloric restriction is ketosis. Increased ketone body concentrations occur during caloric restriction in widely different species ranging from Caenorhabditis elegans to Drosophila to man where ketone bodies are produced in liver from free fatty acids released from adipose tissue.

Ketone bodies were first found in the urine of subjects with diabetes creating in physicians the thought that their presence was pathological. However, it was shown that ketone bodies were the normal result from fasting in man, where they could be used in man in most extrahepatic tissue including brain. The ketone bodies, D-β-hydroxybutyrate (D-βHB) and its redox partner acetoacetate are increased during fasting, exercise, or by a low carbohydrate diet. Originally ketone bodies were thought to be produced by a reversal of the β-oxidation pathway of fatty acids. However, it was definitively and elegantly shown that the β-hydroxybutyrate of the β oxidation pathway was of the L form while that produced during ketogenesis was the D form. This fundamental difference in the metabolism of the D and L form of ketone bodies has profound metabolic effects.

Recently, it was shown that administration of D-βHB to C. elegans caused an extension of life span resulting in that ketone body to be presciently labeled as "an anti-aging ketone body". In the same experiment, L-β-hydroxybutyrate failed to extend life span. If it is accepted that the ketone body, D-βHB is an "anti-aging" compound, this could account for the widespread observation that caloric restriction, and its resultant ketosis, leads to life span extension. Many aging-induced changes, such as the incidence of malignancies in mice, the increases in blood glucose and insulin caused by insulin resistance, and the muscular weakness have been shown to be decreased by the metabolism of ketone bodies, a normal metabolite produced from fatty acids by liver during periods of prolonged fasting or caloric restriction.

In addition to ameliorating a number of diseases associated with aging, the general deterioration of cellular systems independent of specific disease seems related to reactive oxygen species toxicity and the inability to combat it. In contrast increases in life span occur across a number of species with a reduction in function of the insulin signaling pathway and/or an activation of the FOXO transcription factors, inducing expression of the enzymes required for free radical detoxification. In C. elegans, these results have been accomplished using RNA interference or mutant animals. Similar changes should be able to be achieved in higher animals, including humans, by the administration of d-βHB itself or its esters.

In summary, decreased signaling through the insulin/IGF-1 receptor pathway increases life span. Decreased insulin/IGF-1 receptor activation leads to a decrease in PIP3, a decrease in the phosphorylation and activity of phosphoinositide-dependent protein kinase (PDPK1), a decrease in the phosphorylation and activity of AKT, and a subsequent decrease in the phosphorylation of FOXO transcription factors, allowing them to continue to reside in the nucleus and to increase the transcription of the enzymes of the antioxidant pathway. In mammals, many of these changes can be brought about by the metabolism of ketone bodies. The metabolism of ketones lowers the blood glucose and insulin thus decreasing the activity of insulin signaling and its attendant changes in the pathway described above. However, in addition ketone bodies act as a natural inhibitor of class I HDACs, inducing FOXO gene expression stimulating the synthesis of antioxidant and metabolic enzymes. An added important factor is that the metabolism of ketone bodies in mammals increases the reducing power of the NADP system providing the thermodynamic drive to destroy oxygen free radicals which are a major cause of the aging process.

Heart Disease Risk Factors in Middle Age Predict Remaining Life Expectancy

Researchers have processed data from a long-running study to show that the presence or absence of heart disease risk factors in middle age predicts remaining life expectancy. Those with no risk factors live a somewhat longer, on average. It is interesting to note that only a small portion of the population are free from all risk factors at this stage in life, and that is largely the result of poor lifestyle choices leading to excess fat tissue and vascular decline. In an age of rapid progress in biotechnology, with effective treatments for the causes of aging on the horizon, it makes sense to avoid sabotaging your own health in this way. A few years might make the difference between living to benefit from the first rejuvenation therapies, or missing that boat entirely.

People with no major heart disease risk factors in middle age stay healthy and live longer, according to a 40-year study. Compared to those who had two or more high risk factors in middle age, those who reached age 65 without a chronic illness lived an average 3.9 years longer and survived 4.5 years longer before developing a chronic illness, researchers found. They also spent 22 percent fewer of their senior years with a chronic illness - 39 percent compared to 50 percent - and saved almost $18,000 in Medicare costs.

Researchers examined data from the Chicago Health Association study, which included initial health assessments in the late 1960s/early 1970s and has followed participants on an ongoing basis using Medicare health records. Researchers determined how many participants had favorable factors such as non-smokers, free of diabetes, normal weight, blood pressure and cholesterol levels versus those with elevated risk factors or high risk factors. Looking solely at heart disease in 18,714 participants who reached age 65 without having a heart attack, stroke or congestive heart failure, those with all favorable risk factors lived 6.9 years longer without heart disease and spent 46.5 percent fewer of their senior years with heart disease.

"We need to think about cardiovascular health at all stages of life. The small proportion of participants with favorable levels in their 40s is a call for all of us to maintain or adopt healthy lifestyles earlier in life. But risk factors and their effects accumulate over time, so even if you have risks it's never too late to reduce their impact on your later health by exercising, eating right, and treating your high blood pressure, cholesterol and diabetes." The data is even more grim than a 2011-12 national survey suggesting only 8.9 percent of U.S. adults age 40-59 had five or more "ideal" health factors.

Link: http://news.heart.org/later-years-golden-when-heart-is-healthy-at-middle-age/

DNA-PK and Age-Related Decline in Mitochondrial Function

Researchers here have identified one of the proximate causes of mitochondrial decline with aging. The research is pitched as a path to helping control obesity, as that is where the funding is, sadly, but is much more interesting in the context of aging and reduced mitochondrial function. Beyond the sort of damage to mitochondrial DNA described in the SENS view of aging, later life is accompanied by a more general loss of mitochondrial activity, and that is the context for this research. It is important in most tissues, but especially so in those that require a larger amount of energy to function, such as the brain. Loss of mitochondrial capacity is implicated in all of the common neurodegenerative conditions, for example.

A team of scientists has identified an enzyme that could help in the continuous battle against mid-life obesity and fitness loss. They used mice to test the potentially key role this enzyme plays in obesity and exercise capacity. They administered an inhibitor that blocked the enzyme in one group being fed high-fat foods, but withheld it in another. The result was a 40 percent decrease in weight gain in the group that received the inhibitor. Researchers have known for years that losing weight and maintaining the capacity to exercise tend to get harder beginning between ages 30 to 40 - the start of midlife. Scientists have developed new therapies for obesity, including fat-fighting pills. However, many of those therapies have failed because of a lack of understanding about the biological changes that cause middle-aged people to gain weight, particularly around their abdomen.

Researchers searched for biochemical changes that occurred in middle-aged animals (human equivalent of 45 years). They found that an enzyme called DNA-dependent protein kinase, or DNA-PK, increases in activity with age. Further work showed that DNA-PK promotes conversion of nutrients to fat and decreases the number of mitochondria, tiny organelles in the cells that turn fat into energy to fuel the body. Mitochondria can be found in abundance among young people, but the numbers drop considerably in older people. Researchers know that decreased mitochondria can promote obesity as well as loss of exercise capacity. The researchers theorized that reducing DNA-PK activity may decrease fat accumulation and increase mitochondria number as well as promote fat burning. The researchers tested their theory by orally administering a drug that inhibits DNA-PK and found that, in addition to preventing weight gain in the mice, the inhibitor drug boosted mitochondrial content in skeletal muscle, increased aerobic fitness in obese and middle aged mice, and reduced the incidence of obesity and type-2 diabetes. The study opens the door to the development of a new type of weight-loss medication that could work by inhibiting DNA-PK activity, however DNA-PK inhibitors have yet to be tested this way in humans.

Link: https://www.nhlbi.nih.gov/news/press-releases/2017/nih-discovery-mice-could-lead-new-class-medications-fight-mid-life-obesity

Exploration of PPARδ as a Target for Exercise Mimetic Drugs

The field of exercise mimetics is still young, but quite similar at the high level to the more established attempts to find drugs that mimic portions of the calorie restriction response. Exercise and calorie restriction are the two most obvious, well-studied, and reliable means of adjusting the operation of metabolism in order to improve health and extend healthy life span. Sadly, the long-term effects on life span in long-lived species such as our own are nowhere near as large as those exhibited by short-lived species such as laboratory mice. Nonetheless, given that exercise and calorie restriction produce benefits that are larger and more robust than anything that can be achieved for healthy people with presently available medical technology (a state of affairs that we hope will soon change), there is considerable interest in developing drugs that can achieve similar outcomes. In principle at least, these altered states of metabolism have points of control and regulation, a small number of proteins and genes that can be targeted by therapeutics.

Unfortunately the complexity of cellular metabolism, combined with the fact that near all of it changes in response to exercise or calorie restriction, makes it challenging to achieve progress in this field - to find and safely adjust the points of control that must be in there somewhere. Going on for two decades of calorie restriction mimetic research has so far resulted in little to show for the effort involved beyond an incrementally better understanding of some narrow slices of the biochemistry involved. Efforts to produce exercise mimetics may or may not go the same way, but there is certainly no reason to expect it to be any easier. Nonetheless, there are a few promising lines of work underway, such as the one covered by the research materials below. The results presented here are of interest for managing to split out aspects of exercise and endurance into facets that can be adjusted distinctly, rather than for showing positive results in the exercise capacity of mice. The particular drug used in the study was abandoned for human development ten years ago due to concerns about cancer risk. As a tool rather than a potential therapy, it will probably prove to be very useful in further exploration of the biochemistry controlling the short-term and long-term responses to exercise in mammals.

"Exercise-in-a-pill" boosts athletic endurance by 70 percent

Developing endurance means being able to sustain an aerobic activity for longer periods of time. As people become more fit, their muscles shift from burning carbohydrates (glucose) to burning fat. So researchers assumed that endurance is a function of the body's increasing ability to burn fat, though details of the process have been murky. Previous work into a gene called PPAR delta (PPARD) offered intriguing clues: mice genetically engineered to have permanently activated PPARD became long-distance runners who were resistant to weight gain and highly responsive to insulin - all qualities associated with physical fitness. The team found that a chemical compound called GW1516 (GW) similarly activated PPARD, replicating the weight control and insulin responsiveness in normal mice that had been seen in the engineered ones. However, GW did not affect endurance (how long the mice could run) unless coupled with daily exercise, which defeated the purpose of using it to replace exercise.

In the current study, researchers gave normal mice a higher dose of GW, for a longer period of time (8 weeks instead of 4). Both the mice that received the compound and mice that did not were typically sedentary, but all were subjected to treadmill tests to see how long they could run until exhausted. Mice in the control group could run about 160 minutes before exhaustion. Mice on the drug, however, could run about 270 minutes - about 70 percent longer. For both groups, exhaustion set in when blood sugar (glucose) dropped to around 70 mg/dl, suggesting that low glucose levels (hypoglycemia) are responsible for fatigue.

To understand what was happening at the molecular level, the team compared gene expression in a major muscle of mice. They found 975 genes whose expression changed in response to the drug, either becoming suppressed or increased. Genes whose expression increased were ones that regulate breaking down and burning fat. Surprisingly, genes that were suppressed were related to breaking down carbohydrates for energy. This means that the PPARD pathway prevents sugar from being an energy source in muscle during exercise, possibly to preserve sugar for the brain. Activating fat-burning takes longer than burning sugar, which is why the body generally uses glucose unless it has a compelling reason not to - like maintaining brain function during periods of high energy expenditure. Although muscles can burn either sugar or fat, the brain prefers sugar, which explains why runners who "hit the wall" experience both physical and mental fatigue when they use up their supply of glucose.

Interestingly, the muscles of mice that took the exercise drug did not exhibit the kinds of physiological changes that typically accompany aerobic fitness: additional mitochondria, more blood vessels and a shift toward the type of muscle fibers that burn fat rather than sugar. This shows that these changes are not exclusively driving aerobic endurance; it can also be accomplished by chemically activating a genetic pathway. In addition to having increased endurance, mice who were given the drug were also resistant to weight gain and more responsive to insulin than the mice who were not on the drug.

PPARδ Promotes Running Endurance by Preserving Glucose

In endurance sport competitions such cycling, marathon runs, race walking, and cross-country skiing, "hitting the wall" is a dramatic demonstration of sudden and complete exhaustion. It is thought to be due to the depletion of liver and muscle glycogen and can be averted by training that promotes mitochondrial biogenesis, increased type I fibers, and enhanced fatty acid burning. In this study, we show that PPARδ expression correlates with endurance, and its activation by exercise mimetics, such as GW, is sufficient to increase running time by ∼100 min without changes in either muscle fiber type or mitochondrial biogenesis. Thus, the foundational core of endurance enhancement appears to be purely metabolic. Furthermore, even though the GW impact appears to be achieved via increased fatty acid metabolism, the strongest correlation to endurance is maintenance of blood glucose above 70 mg/dL.

This work identifies PPARδ as both the master regulator and key executor of adaptive changes in energy substrate use in skeletal muscle. Notably, pharmacologic activation of PPARδ replicates the exercise-induced changes in substrate utilization to preserve systemic glucose and thereby delay the onset of hypoglycemia, or "hitting the wall." While exercise-induced muscle remodeling is well documented, the health benefits have been largely attributed to mitochondrial biogenesis and fiber-type transformation. In contrast, pharmacophores that activate PPARδ promote endurance through preserving glucose, essentially "pushing back the wall," without affecting mitochondrial biogenesis or fiber-type transformation. This ability to chemically activate energetic circuits regulated by PPARδ has the potential to confer health benefits in a variety of human diseases.

Reporting on the Second Interventions in Aging Conference

This report captures the state of the research community in a nutshell: progress in the sense that ever more scientists are willing to make the treatment of aging the explicit goal of their research, but, unfortunately, there is still a long way to go in improving the nature of that research. It is still near entirely made up of projects that cannot possibly produce a robust and large impact on human life span. The only course of action likely to extend life by decades in the near future is implementation of the SENS vision for rejuvenation therapies - to repair the molecular damage that causes aging. Everything else on the table is some form of tinkering with the operation of metabolism in order to slightly slow down the accumulation of that damage, such as via capturing some of the calorie restriction response or boosting autophagy. In any machinery, repair is a vastly better strategy for improving function and extending working life span, and our biology is no exception.

In March 2017, the Second Interventions in Aging Conference was held in Cancun, Mexico. The meeting, similar to the earlier event in 2015, was focused on interventional strategies. One notable difference was that this year's meeting was much more directed toward potential interventions to target human aging. The field has been very successful over the last decade in identifying interventions that extend lifespan and healthspan in animal models such as yeast, flies, worms, mice and, to some extent, primates. However, the primary goal is to employ knowledge from basic aging research to develop novel medical strategies aimed at extending human healthspan. Aging is the biggest risk factor for a wide range of chronic diseases that, to date, medical strategies have treated as separate entities, and as they arise. Yet, aging is driven by a limited number of coordinated pathways that can be modulated, and evidence suggests that interventions delaying aging will protect against multiple age-related diseases simultaneously. Discoveries in basic aging research thus point towards a broad-spectrum, preventative, medical strategy for aging-related disease.

There were seven research topics each addressed thematically at the meeting. All were chosen because they embody different strategies to target human aging. Each session combined talks from Platform speakers with those chosen from submitted abstracts. The first and largest theme was targeted toward Organismal Aging, or understanding the intrinsic pathways that govern aging of the entire organism. The interesting aspect of these presentations is that they address strategies to modify aging that touch back to research from the early days of aging research while simultaneously pointing to novel strategies for future interventions: new mechanisms linking growth hormone signaling to aging; using mammalian models to re-evaluate the role of reactive oxygen species; new evidence for links between progeria and normal aging, interpreting these strategies in the context of possible interventions that may affect both normal and "premature" aging; linking NFκB signaling to sarcopenia, a major driver of frailty in aging; mechanisms linking calorie restriction to lifespan extension in primates; strategies to examine the impact of aging pathways in elderly human populations.

The second theme was focused on using Stem Cells to target aging, with exciting presentations on aging of epithelial stem cells in flies and mice, on links between metabolism, autophagy and aging in the hematopoietic system, and on how adult stem cells self-organize into functional configurations. The third theme, addressing Cellular Mechanisms of Longevity Assurance, focused on pathways suspected to modulate aging, including autophagy, mitochondrial function and aging with emphasis on the role of small mitochondrial peptides, and the hypoxia pathway. Theme 4 centered on Epigenetics, which is not only becoming a target for intervention in aging, but is rapidly becoming a leading candidate for providing biomarkers of biological age: mechanisms leading to transgenerational inheritance of epigenetic marks that impact lifespan; links between the epigenome and activation of somatic retrotransposons, and how this activation may drive senescence and aging; further promoting the epigenetic clock as a marker of accelerated and delayed aging.

Theme 5 was designed to take a Systems Aging viewpoint. Such a holistic understanding of the aging process is in a sense the ultimate goal of the research. Is it possible to understand such a complex process as aging not just one gene and pathway at a time but in totality? The final theme centered on Signaling and Metabolism, hitting the major metabolic pathways that are linked to aging and that can be targeted with interventional strategies. These include the mTOR pathway and rapalogs; dietary restriction and links through mTOR to regulation of mRNA splicing; NAD metabolism and sirtuins; mitochondrial roles in regulating aging and metabolism.

Link: http://dx.doi.org/10.18632/aging.101221

Altered Lipid Metabolism Improves Healing and Reduces Inflammation

Researchers here demonstrate that tinkering with the normal operation of lipid metabolism in mice can improve healing and reduce inflammation following a heart attack, suggesting that the approach may have broader applications in cardiovascular disease.

Two immune responses are important for recovery after a heart attack - an acute inflammatory response that attracts leukocyte immune cells to remove dead tissue, followed by a resolving response that allows healing. Failure of the resolving response can allow a persistent, low-grade nonresolving inflammation, which can lead to progressive acute or chronic heart failure. Using a mouse heart attack model, researchers have shown that knocking out one particular lipid-modifying enzyme, along with a short-term dietary excess of a certain lipid, can improve post-heart attack healing and clear inflammation.

Why are lipids and lipid-modifying enzymes important in inflammation and resolving inflammation? Three key lipid modifying enzymes in the body change the lipids into various signaling agents. Some of these signaling agents regulate the triggering of inflammation, and others promote the reparative pathway. The lipids modified by the enzymes are two types of essential fatty acids that come from food, since mammals cannot synthesize them. One is n-6 or omega-6 fatty acids, and the other type is n-3 or omega-3 fatty acids. The balance of these two types is important. The three main lipid-modifying enzymes compete with each other to modify whatever fatty acids are available from the diet. So, researchers asked, what will happen if we knock out one of the key enzymes, the 12/15 lipoxygenase? They reasoned that this would increase the metabolites produced by the other two main enzymes, cyclooxygenase and cytochrome P450 because they no longer had to compete with 12/15 lipoxygenase for lipids to modify. This might be a benefit because those signaling lipids produced through the cyclooxygenase and cytochrome P450 pathways were already known to lead to major resolution promotion factors for post-heart attack healing.

The researchers found that knocking out the 12/15 lipoxygenase and feeding the mice a short-term excess of polyunsaturated fatty acids led to increased leukocyte clearance after experimental heart attack, meaning less chronic inflammation. It also improved heart function, increased the levels of bioactive lipids during the reparative phase of healing, and led to higher levels of reparative cytokine markers. Additionally, the heart muscle showed less of the fibrosis that is a factor in heart failure. Besides congestive heart failure, persistent inflammation aggravates a vicious cycle in many cardiovascular diseases. Further mechanistic studies are warranted to develop novel targets for treatment and to find therapies that support the onset of left ventricle healing and prevent heart failure pathology.

Link: http://www.uab.edu/news/innovation/item/8266-mice-with-missing-lipid-modifying-enzyme-heal-better-after-heart-attack

Stepping Towards Better Assays for Cellular Senescence

Growth in the number of lingering senescent cells in all tissues is one of the root causes of aging. These cells generate signals that provoke chronic inflammation, destructively remodel nearby extracellular matrix structures, and alter the behavior of other cells for the worse. As their numbers grow, so does the negative impact on organ function and the acceleration of dysfunction that eventually becomes age-related disease. Cells become senescent when they reach the limit of on cell divisions that is imposed on most of the cells in the body, but also in response to genetic or other damage, or in the face of a toxic environment. Near all such cells destroy themselves, or are destroyed by the immune system. A tiny fraction evade this fate, however, and given enough time that tiny fraction would be enough to push us into frailty, disease, and death, even absent the other causes of degenerative aging.

Fortunately, targeted removal of senescent cells as a treatment for aging is becoming a reality. Numerous methods and drug candidates are under development, with varying degrees of evidence resulting from animal studies, ability to destroy senescent cells, and unwanted side-effects. A number of the drug candidates are chemotherapeutics, such as navitoclax, with significant and unpleasant side-effects to account for, but other approaches, such as the Oisin Biotechnologies gene therapy or the new FOXO4-p53 technique may well have next to no side-effects. Many people are presently in a position to order delivery of at least some of the tested compounds that already in the drug databases and give it a try, though most of the manufacturers are unwilling to sell to the public at large, for regulatory and liability reasons. There is at least a little more forethought that has to go into unofficial self-experimentation beyond just ordering the stuff and guessing a dosage, even for compounds for which the pharmacology is well-defined because they were previously tested in humans for one purpose or another.

That said, the big hurdle for self-experimentation is the lack of good assays. It is pointless to try this out unless you believe you have a good way to assess the results. Admittedly the results in mice seem pretty impressive, but it may nonetheless still be the case that unless you are very impacted by senescent cells, then just running bloodwork - or checking kidney function, or using CT scans to assess arterial calcification, or estimating your own joint pain, and so forth - will give you an ambiguous result. What is really needed is a way to see how many senescent cells are in your tissue, before and after a modest, limited dose. Today that really requires tissue sections and staining approaches, which is custom lab work, somewhat clunky, and there is some question as to how clearly a tissue biopsy from a human subject is going to show the desired information. Since senescent cells are involved in wound healing, the whole biopsy process might involve generating enough new senescent cells to confuse the data. To me it seems largely pointless to embark upon a personal test of the more easily obtained drug candidates without the ability to check before and after in a rigorous way.

This is essentially why I chose to support the work of CellAge, given their focus on clinically useful assays of cellular senescence. There are numerous groups working on improving the situation for assays of senescent cells, but the academic researchers are largely aiming at something other than improvements that are convenient for human self-experimentation or later clinical tests. There is probably more interest, as illustrated in this paper, in trying to better capture variations in senescent cell biochemistry, or better classify different types of senescence.

Quantitative identification of senescent cells in aging and disease

Our understanding of the role of cellular senescence in different biological contexts has been impeded in part by the difficulty of detecting their presence within tissues. Such detection is currently performed mainly by evaluation of senescence-associated beta-galactosidase (SA-β-gal). However, SA-β-gal activity alone is not enough to allow us to conclude with confidence that cells are senescent, as positive staining can also occur in other biological contexts. Therefore, SA-β-gal staining is usually combined with staining for additional markers such as γH2AX-a marker for activation of DNA damage response. In addition, negative markers that should be absent in senescent cells can be used to exclude the cells that are not senescent. These markers indicate cell proliferation, like Ki67 or BrdU incorporation, or proteins ubiquitously present in the cell nuclei, but secreted from senescent cells and thus absent in their nucleus, like HGMB1.

The SA-β-gal and each of the markers are usually evaluated separately in consecutive sections. This procedure is not only laborious and expensive but also does not allow multiple senescence biomarkers to be detected within the same cells, limiting the possibility of quantitative evaluation of senescent cells derived from tissues. Alternatively, SA-β-gal activity within cells can be quantified by flow cytometry using 5-dodecanoylaminofluorescein di-β-D-galactopyranoside as a substrate. However, this method can be performed only on intact cells and therefore does not allow identification of intracellular markers in the same cells. Altogether, current methods do not allow detection and quantification of senescent cells in tissues based on combination of markers that is essential for their confident identification.

Conventional SA-β-gal staining fails to distinguish between different cell types that can be a source of senescent cells within complex tissues, limiting our understanding of the underlying biological phenomena. In an attempt to overcome the limitations of current methods for identification of senescent cells, we utilized ImageStreamX, an advanced imaging flow cytometer capable of producing multiple high-resolution, fluorescent and bright-field (BF) images of every cell directly in flow. Our approach combines the quantitative power of flow cytometry with high-content image analysis. We modified the traditional SA-β-gal assay to meet the requirements of the ImageStreamX and performed the assay in a single-cell suspension. Using this method, we identified and quantified senescent cells in tumors, fibrotic tissues, and normal tissues of young and aged mice.

In this study, we evaluated several biomarkers of cellular senescence and found a significant correlation between SA-β-gal staining and the lack of nuclear HMGB1 staining in vitro. This combination might allow more reliable identification of senescent cells, compared to SA-β-gal assay alone. Therefore, it provides significant advantage over existing techniques, including the use of fluorescent β-gal substrate, which does not allow combination staining with any intracellular molecular markers. Accordingly, it seems possible to take advantage of this method to screen for new senescence biomarkers that correlate with SA-β-gal activity in vivo, and would consequently open the way to a deeper understanding of the senescent state in vivo. Furthermore, the use of senescence biomarkers will potentially yield greater biological insight by allowing protein localization and colocalization to be monitored and compared between senescent and nonsenescent cells.

Through its use of cell-type-specific biomarkers, our protocol can successfully determine which cell types undergo cellular senescence and which do not. Importantly, in the experiments with mice of different age, SA-β-gal staining was performed for 12 hours in all tissues to ensure consistency. We suggest that in future studies SA-β-gal staining time has to be calibrated for each tissue and in some circumstances even different cell population, to achieve the most accurate results. Moreover, staining of the cells for live-dead markers immediately following tissue dissociation will allow quantification of SA-β-gal-positive cells specifically from the live cell population. This is particularly pertinent since the dissociation of cells from tissues might result in a certain amount of cell death. We showed that about 96% of the cells are viable following tumor dissociation, but this percentage can diverse greatly depending on the tissue examined.

Engineered Cells Act to Reduce Inflammation in Controlled Way

A few days ago, I noted a use of CRISPR to suppress chronic inflammation via epigenetic alterations that interfere with the signaling that promotes the inflammatory response. Here I'll point out a different, arguably more sophisticated approach to achieving the same end, also using CRISPR to achieve the necessary genetic edits, but in this case turning stem cells into regulators that damp down inflammatory signaling only when required. Rising levels of inflammation in aging are a contributing factor that speeds progression of most of the common age-related conditions. Finding ways to suppress this inflammation without further damaging the diminished immune response should prove to be broadly beneficial, though not as desirable an end goal as repairing the immune system as a whole, restoring its balanced and youthful function.

Chronic inflammatory diseases such as arthritis are characterized by dysregulated responses to pro-inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor α (TNF-α). Pharmacologic anti-cytokine therapies are often effective at diminishing this inflammatory response, but due to the pleiotropic roles of TNF-α and IL-1 and their involvement in tissue homeostasis, the use of such therapies may have significant side effects, including increased susceptibility to infection as well as to autoimmune diseases. Moreover, excess inhibition of these cytokines can interfere with tissue regeneration and repair. Therefore, methods to dynamically deliver precisely calibrated doses of anti-inflammatory biologic therapies could improve treatments by combating cytokine-mediated pain and degeneration while spatially and temporally regulating the production of anti-cytokine drugs.

Here, we propose a regenerative medicine approach to the treatment of chronic inflammatory diseases by engineering cells that execute real-time, programmed responses to environmental cues, including pro-inflammatory cytokines. We used genome editing with the CRISPR/Cas9 system to create stem cells that antagonize IL-1- and TNF-α-mediated inflammation in an autoregulated manner. To achieve this, we selected to overtake the chemokine (C-C) ligand 2 (Ccl2) gene, which is also known as macrophage chemoattractant protein-1 (Mcp-1). The Ccl2 gene product regulates trafficking of monocytes/macrophages, basophils, and T lymphocytes. TNF-α and IL-1 serve as two of the most potent stimulators of Ccl2 expression; however, the persistence of Ccl2 expression depends on continued exposure to inflammatory cues, so resolution of inflammation results in rapid decay of Ccl2 transcripts.

Thus, we performed targeted gene addition of IL-1 and TNF-α antagonists at the Ccl2 locus to confer cytokine-activated and feedback-controlled expression of biologic therapies. These programmed stem cells were then used to engineer articular cartilage tissue to establish the efficacy of self-regulated therapy toward protection of tissues against cytokine-induced degeneration. We hypothesized that this approach of repurposing normally inflammatory signaling pathways would allow for transient, autoregulated production of cytokine antagonists in direct response to cytokine stimulation. This type of approach could provide an effective "vaccine" for the treatment of chronic diseases while overcoming limitations associated with delivery of large drug doses or constitutive overexpression of biologic therapies.

Link: http://dx.doi.org/10.1016/j.stemcr.2017.03.022

Bioprinting Structurally Correct Cartilage Tissue

Cartilage regenerates poorly, and thus injury and wear and tear make joint pin and dysfunction comparatively common conditions. The tissue engineeering of cartilage should provide a basis for regenerative therapies for all such medical issues, but has proven challenging. Researchers have struggled to generate the correct load-bearing structural properties, determined by the arrangement of the extracellular matrix, which is constructed by the cells in response to environmental signals. Here, however, researchers claim success in using a bioprinting approach to build cartilage that closely matches the real thing.

The team used cartilage cells harvested from patients who underwent knee surgery, and these cells were then manipulated in a laboratory, causing them to rejuvenate and revert into "pluripotent" stem cells, i.e. stem cells that have the potential to develop into many different types of cells. The stem cells were then expanded and encapsulated in a composition of nanofibrillated cellulose and printed into a structure using a 3D bioprinter. Following printing, the stem cells were treated with growth factors that caused them to differentiate correctly, so that they formed cartilage tissue.

Most of the team's efforts had to do with finding a procedure so that the cells survive printing, multiply and a protocol that works that causes the cells to differentiate to form cartilage. "We investigated various methods and combined different growth factors. Each individual stem cell is encased in nanocellulose, which allows it to survive the process of being printed into a 3D structure. We also harvested mediums from other cells that contain the signals that stem cells use to communicate with each other so called conditioned medium. In layman's terms, our theory is that we managed to trick the cells into thinking that they aren't alone." A key insight gained from the team's study is that it is necessary to use large amounts of live stem cells to form tissue in this manner.

The cartilage formed by the stem cells in the 3D bioprinted structure is extremely similar to human cartilage. Experienced surgeons who examined the artificial cartilage saw no difference when they compared the bioprinted tissue to real cartilage, and have stated that the material has properties similar to their patients' natural cartilage. Just like normal cartilage, the lab-grown material contains Type II collagen, and under the microscope the cells appear to be perfectly formed, with structures similar to those observed in samples of human-harvested cartilage.

Link: http://sahlgrenska.gu.se/english/research/news-events/news-article//success-in-the-3d-bioprinting-of-cartilage.cid1438435