The Goal of Symbiotic Microbes in Tissues, Generating Additional Oxygen as Required

We live in an era of biotechnology, of tremendous year by year increases in the capacity to engineer the fundamental mechanisms of life and disease. The research community and funding institutions should aim high, aim at the new and the amazing, rather than slouching forward in the service of crafting yet more marginal, incremental improvements to existing forms of therapy. Sadly, mediocrity rules when it comes to all too much of the research community. Vision is lacking, and far too few people are willing to tread the roads yet untraveled.

Why is it necessary to spend so much time and effort to convince people to fund and work on rejuvenation therapies after the SENS model, based on the repair of cell and tissue damage? Because this strategy is comparatively new, because it is different from the largely futile efforts to paper over age-related diseases that have gone before. We humans are conservative, and favor existing strategies, even when they are poor, even when new directions are highly promising. Beyond the matter of rejuvenation, there are a thousand plausible new directions in medicine and biotechnology that are given little attention for all the same reasons, whether the DRACO approach to defeating viruses, or the topic of today's paper, the introduction of symbiotic bacteria capable of generating oxygen to supply ischemic tissues.

The researchers here focus on treatment of ischemia following heart attack or stroke, and on largely unmodified symbiotic organisms that might be used for this purpose. This is but a single step upon a long road of possibilities. Why not an enhancement biotechnology for healthy people, in which symbiotic bacteria dwell in the body, ready to provide oxygen on demand? A gene therapy to add a wholly artificial gene to human cells, one connected to a promoter that triggers only in hypoxic conditions, with the result that it supplies a protein that engineered symbiotic microorganisms consume as fuel for their oxygen-production engines. This sort of machinery could be described in some detail today, then built with today's technology, tested in animals, and delivered into human tissues with the robust gene therapy platforms that will emerge over the next decade. The result will people resilient to drowning, people with incredible endurance, people who can survive heart attacks, strokes, and other forms of blood vessel injury with little additional damage.

This will not happen any time soon, but not because it is technically infeasible. It will not happen because there is little overlap in this world between those with ambition on the one hand, and those with funding and power on the other. In this age of rapid, radical progress in biotechnology, there is all too little will to reach for the myriad possibilities offered.

Photosynthetic symbiotic therapy

Engineered O2-producing biomaterials represent an emerging field with enormous potential to address tissue ischemia and hypoxia without revascularization. The clinical applications span nearly the entire domain of medicine and include the areas of tissue engineering and regeneration, organ preservation, wound healing, diabetic microvascular disease, and cardiovascular, cerebrovascular, and peripheral vascular disease. Nature, however, evolved the most elegant O2-producing biomaterial 3.5 billion years ago in the form of photosynthetic cyanobacteria, which are responsible for the relative abundance of O2 in Earth's atmosphere today. These ancestors of the chloroplast convert CO2 and water into O2 and glucose using light as an energy source. Recently, teams have begun to engineer symbioses between cyanobacteria or other photoautotrophic algae and heterotrophic cells such as those of mammals. In this relationship, the photosynthetic microorganism recycles CO2 produced by heterotrophic cellular respiration and generates O2 that helps sustain the heterotrophic partner.

The first use of a photosynthetic microorganism to remedy tissue hypoxia in vivo was reported in 2012. By placing a gas-permeable pouch containing a light-emitting diode and the photosynthetic microalga Chlorella vulgaris in the perfluorocarbon-filled peritoneal cavity of hypoventilated rats, the team demonstrated that Chlorella could supplement gas exchange in rats with respiratory insufficiency. The researchers also explored the use of photosynthetic symbiosis to enhance the viability of heterotopically-transplanted rat pancreases harvested 3 hours after cardiac death. The team demonstrated that a majority of diabetic recipient rats receiving pancreases stored in traditional cold preservation solution for 30 minutes exhibited severe glucose dysregulation and died within 5 hours after surgery. All rats receiving pancreases stored similarly but with Chlorella in gas-permeable bags at mild hypothermia (22°C), however, had normal blood glucose levels and survived beyond 1 week after surgery.

Direct inoculation of host tissues with microorganisms in solution risks rapid loss of the symbiotic microbes. Although no in vivo study has yet to demonstrate a significant immune response against a photosynthetic symbiont (i.e. against S. elongatus or C. reinhardtii in zebrafish, mouse, or rat models), delivery via a bioengineered construct nevertheless reduces the rate of cell dispersal. To this end, researchers have conducted impressive pioneering work on the development of photosynthetic algae-seeded scaffolds. Using an FDA-approved collagen-based scaffold, the team demonstrated that C. reinhardtii seeded within the scaffold were able to photosynthesize effectively and even proliferate. Moreover, C. reinhardtii co-cultured with murine fibroblasts within the scaffold were able to supply the fibroblasts with O2 in hypoxic conditions.

Thus far, photosynthetic symbiotic therapies have not taken full advantage of the immense genetic adaptability of cyanobacteria and microalgae. While researchers engineered C. reinhardtii to express and secrete vascular endothelial growth factor (VEGF), resulting in O2 delivery as well as neoangiogenesis when delivered into zebrafish and rat tissues in vivo, nearly all attempts to treat tissue ischemia or hypoxia using photosynthetic symbiosis have focused solely on gas exchange alone. Future studies should aim to expand the arsenal of clinically useful compounds produced by the photosynthetic symbiont and thereby augment its therapeutic potential. Overall, photosynthetic symbiosis represents a valuable untapped strategy for the development of novel engineered O2-generating biomaterials.

The Interactions of Frailty, Exercise, and Risk of Dementia

Frailty is a consequence of advanced aging, a categorization applied to an individual who is greatly physically weakened by the accumulation of cell and tissue damage and its many downstream consequences. Frailty is generally described as some combination of the loss of muscle mass and strength known as sarcopenia, fragility of bones caused by osteoporosis, and a faltering immune system that no longer adequately protects against pathogens, coupled with outcomes such as weakness, exhaustion, and weight loss. The underlying root causes of frailty are also the causes of other age-related conditions, and it is thus expected to find that frail individuals also exhibit a greater incidence of a range of conditions, such as dementia.

How is it that some people can have a brain full of plaques and tangles, yet somehow fend off dementia? Researchers analyzed postmortem data from 456 participants in the Rush Memory and Aging Project (MAP). At their last visit before death, 242 had a diagnosis of possible or probable Alzheimer's disease (AD). Using information gathered from past clinical visits, the researchers calculated a frailty index for each based on a 41-item questionnaire that assessed age-related symptoms, morbidities, and functional deficits. The final score represented a fraction of the total possible deficits. For this cohort, who averaged 89.7 years of age at death, the mean frailty index was 0.42, right at the threshold between moderately and severely frail.

Compared with people who were less frail, those whose frailty was above average were older, likelier to have been diagnosed with AD dementia, and had a higher burden of amyloid-β plaques and tau tangles at autopsy. Thirty-five participants who had not been diagnosed with dementia, but who had a high burden of plaques and tangles, turned out to have low frailty scores. On the other side of the spectrum, 50 who had been diagnosed with dementia but had little AD pathology had the highest frailty indexes. Overall, the findings tied frailty to dementia, and suggested that less frail people are better able to withstand a given amount of AD pathology than their more fragile counterparts.

Could dementia have caused the frailty? The researchers could not rule out reverse causality with their cross-sectional data. However, they did find that the relationship among frailty, pathology, and dementia remained even when they corrected the frailty index for functional deficits that can be caused by dementia, or when they controlled for known dementia risk factors, including stroke and hypertension. The findings suggest that the clinical manifestation of AD depends not just on its neuropathology, but also on the extent of the aging process. People age at different rates, and those who do so more rapidly will not only be more likely to develop AD pathology, but also be more sensitive to it. On a positive note, the findings suggest that slowing the broader process of aging - via changes in lifestyle and/or anti-aging therapeutics - might also prevent dementia.


Hypertension May Accelerate Neurodegeneration by Reducing Clearance of Metabolic Waste via Cerebrospinal Fluid Drainage

I missed the open access paper noted here when it appeared last year. It is an interesting addition to the growing body of evidence that shows drainage of cerebrospinal fluid from the brain to be an important mechanism for clearance of metabolic waste. That the drainage paths become impaired with age contributes to the aggregation of proteins such as amyloid-β, involved in the development of Alzheimer's disease. Thus approaches to restore drainage in one way or another should prove quite effective for a range of neurodegenerative conditions. We will find out whether or not this is the case over the next few years as groups like Leucadia and EnClear move beyond animal studies and into human trials.

Cerebrospinal fluid (CSF) aids in the removal of metabolic waste from the brain. The exact anatomical pathways and mechanisms underlying how solutes in the interstitial fluid (ISF) are transported towards CSF remain unclear. Historically, it has been thought that solutes exit the brain along a network of perivascular spaces (PVSs) surrounding cerebral arteries, against the direction of blood flow. Recent in vivo experiments in rodents have shown the opposite: CSF enters the brain along arterial PVSs, and this flow plays a vital role in driving the clearance of amyloid-β (Aβ) from the ISF at more downstream locations

In both cases, indirect experimental evidence suggests that fluid within PVSs is transported via bulk flow and possibly driven by arterial pulsations derived from the cardiac cycle. To evaluate fluid motion within the PVS we have adapted in vivo two-photon imaging to allow measurement of CSF flow speeds simultaneously with recordings of cardiac and respiratory cycles. We have also performed synchronized measurements of the artery diameter and heartbeat to determine vessel wall dynamics. The analysis confirms that CSF bulk flow in the PVS is pulsatile, at the same frequency as the cardiac cycle, and in the same direction as blood flow. Our results are highly consistent with a fluid transport mechanism - perivascular pumping - wherein vascular wall kinetics directly drive pulsatile CSF bulk flow in the PVS.

Finally, we show that high blood pressure, a condition that affects close to half of the world's adult population, disrupts the perivascular pump and sharply slows CSF transport in the PVS. Earlier studies have shown that arterial hypertension promotes the accumulation and aggregation of Aβ. We speculate that hypertension-induced reduction of PVS fluid transport contributes directly to the associations between arterial hypertension and Alzheimer's disease.


GrimAge is the Latest Evolution of the Epigenetic Clock

The original epigenetic clock is a measure of age, a weighted algorithmic combination of specific DNA methylation sites on the genome. Numerous variations on this theme are being produced, and here I'll point out news on the latest, a metric called GrimAge. DNA methylation is an epigenetic mechanism that steers protein production and thus cell behavior. Epigenetic clocks correlate well with chronological age, and it has been shown that populations of older individuals with pronounced age-related disease or otherwise exhibiting higher mortality rates tend to have higher epigenetic ages.

There are some problematic exceptions, groups expected to show higher epigenetic age, but who do not, but researchers are nonetheless forging ahead to try to turn this tool into a robust method of assessing the burden of cell and tissue damage that causes aging. If one or more clock variants can be made robust enough, the variations understood and linked to specific causes and dysfunctions of aging, then these epigenetic clocks offer the possibility of greatly accelerating the development of rejuvenation therapies.

At present the only robust way of demonstrating that a therapy does in fact turn back aging, and measuring the degree to which it does so, is to run life span studies. When using mice, this is a greater expense in time and funds than most research groups can stomach, and carrying out such studies in humans is just out of the question. What is needed is a way to quickly assess how greatly a therapy reduces the burden of aging, a test that can be applied beforehand, and a month or two after treatment, and the result compared. Even as a way to cull the useless and marginal work in the field of human aging, work that consumes far too much attention and funding, this would be very valuable. More importantly, it would allow researchers to more cost-effectively assess scores of promising approaches that are presently lacking in the funds and support to prove their worth.

The epigenetic clock: a molecular crystal ball for human aging?

A hat trick of new epigenetic clocks has recently been published: The Skin and Blood clock provides a more precise estimation of chronological age in tissues and cell types frequently used in research and forensics, while PhenoAge and GrimAge aim to capture biological aging and derive an improved prediction of mortality and morbidity risks. Together, these new epigenetic clocks present valuable tools to investigate human aging, shed light on the question of why we all age differently, and develop strategies to extend human lifespan and healthspan.

Horvath's multi-tissue clock is based on DNA methylation data. DNA methylation, the addition of methyl groups to cytosine bases of the DNA, is the most widely studied epigenetic modification so far. It plays an important role in the regulation of gene expression, altering the phenotype without changing the genotype. A particular locus in the genome can either be methylated or unmethylated. But as DNA methylation measurements are usually obtained from a pool of tens of thousands of cells, what is measured is the proportion of the cells in which a locus is methylated. In many positions of the human genome, this methylation heterogeneity changes with age. These usually small but consistent age-associated changes in DNA methylation are what make the epigenetic clock work. And it works very precisely, with a median absolute error (MAE) of only 3.6 years, clearly outperforming previously used molecular biomarkers of age.

DNA methylation GrimAge strongly predicts lifespan and healthspan

DNA methylation (DNAm) levels have been used to build accurate composite biomarkers of chronological age. DNAm-based age (epigenetic age) estimators predict lifespan after adjusting for chronological age and other risk factors. Moreover, they are also associated with a large host of age-related conditions. Recently, DNAm-based biomarkers for lifespan (time-to-death due to all-cause mortality) have been developed.

Many analytical strategies are available for developing lifespan predictors from DNAm data. The single stage approach involves the direct regression of time-to-death (due to all-cause mortality) on DNAm levels. By contrast, the current study employed a novel two-stage procedure: In stage 1, we defined DNAm-based surrogate biomarkers of smoking pack-years and a selection of plasma proteins that have previously been associated with mortality or morbidity. In stage 2, we regressed time-to-death on these DNAm-based surrogate biomarkers. The resulting mortality risk estimate of the regression model is then linearly transformed into an age estimate (in units of years). We coin this DNAm-based biomarker of mortality "DNAm GrimAge" because high values are grim news, with regards to mortality/morbidity risk.

Using large scale validation data from thousands of individuals, we demonstrate that DNAm GrimAge stands out among existing epigenetic clocks in terms of its predictive ability for time-to-death, time-to-coronary heart disease, time-to-cancer, its strong relationship with computed tomography data for fatty liver/excess visceral fat, and age-at-menopause. Adjusting DNAm GrimAge for chronological age generated novel measure of epigenetic age acceleration, AgeAccelGrim. AgeAccelGrim is strongly associated with a host of age-related conditions including comorbidity count. Overall, these epigenetic biomarkers are expected to find many applications including human anti-aging studies.

The Importance of Macrophages in Kidney Regeneration

Macrophages are demonstrably important in tissue regeneration. The process of regeneration is an intricate dance of signaling and activity carried out between stem and progenitor cells, somatic cells of varying types, senescent cells, and immune cells such as macrophages. The research of recent years strongly suggests that differences in macrophage behavior are in some way fundamental to the exceptional regeneration exhibited by species as diverse as salamanders, zebrafish, and spiny mice. Can macrophage behavior in our species be beneficially adjusted to improve regenerative capacity? Comparatively simple approaches aiming to shift macrophage polarization from the inflammatory, aggressive M1 polarization to the pro-regenerative M2 polarization appear quite promising in early animal studies, but this is just the tip of the iceberg. Much is left to be explored, and articles such as this one only underline the benefits that might be achieved given success.

Acute kidney injury, or AKI, is a devastating condition that develops in two-thirds of critically ill patients, and patients with AKI have a 60 percent risk of dying. In AKI, kidneys can become scarred and can show progressive decline in function, becoming unable to heal their tissue. During development in the womb, immune cells called macrophages go to the kidneys, and they remain there for life. Researchers have found that, during AKI in a mouse model, the kidney-resident macrophages are reprogrammed to a developmental state, resembling these same cells when they are found in newborn mice. Newborn mouse kidneys are still developing. This reprogramming during AKI may be important to promote healing and tissue regeneration. If a similar developmental shift is seen for human kidney-resident macrophages during AKI, that could aid new therapeutic approaches for patients.

Researchers detailed how the kidney-resident macrophages are reprogrammed to a developmental state after injury. In response to the disease model, the kidney-resident macrophages turned off their expression of major histocompatibility complex type II, or MHCII. This lack of expression is similar to kidney-resident macrophages in newborn mice - those mice, the researchers showed, lack expression of this protein up to postnatal day seven, and then begin to express it over the next two weeks. Notably, MHCII protein and macrophages have important roles in autoimmunity and transplant rejection.

In addition, kidney-resident macrophages after AKI underwent transcriptional reprogramming to express a gene profile closely resembling that of the kidney-resident macrophages in newborn mice at postnatal day seven. Further supporting their role in development and healing, the reprogrammed kidney-resident macrophages were enriched in Wnt signaling, an active pathway that is vital for mouse and human kidney development. Many basic science research studies have suggested the importance for tissue-resident macrophages in healing after injury, but development of therapies promoting them is still in early stages.


CXCL12 Promotes Small Artery Growth in Injured Hearts, but Why Not Apply this Approach in Advance of Injury as Well?

While rejuvenation research aims at a world in which no-one ever suffers coronary artery disease or a heart attack, the causes of those conditions prevented and controlled, we still live in a world in which these conditions are accepted as inevitable, and the near term focus of regenerative medicine is structural repair for the survivors after the fact. This is a poor second best, but the research community continues to develop ever better potential means of repair. In this case, in which researchers provoke greater construction of secondary arteries that can support the primary blood vessels of the heart, capable of supplying blood when the primary is damaged, one may ask whether it can also be a means of reducing the impact of structural damage if applied well in advance. Sadly, preventative medicine of this sort is a hard sell in the present regulatory environment. Applying enhancement therapies to older people still considered "healthy" is just not as acceptable a goal as it should be.

Researchers observed that patients with blockages in major arteries feeding the heart often have confoundingly different outcomes. "Some patients have a blockage in one coronary artery and die; other patients have multiple blockages in multiple areas but can run marathons." The difference may be that this second group of patients has collateral arteries, tiny arteries that bypass blockages in hearts' major arteries and feed areas of the heart starved of oxygen. "They are like the side streets that let you get around a traffic jam on the freeway." Such collateral arteries could help people with atherosclerosis or people recovering from a heart attack, except that collateral arteries are only seen in a minority of patients.

Researchers have now discovered how these collateral arteries are formed and a signaling molecule that promotes their growth in adult mice, offering hope that collateral arteries may be coaxed to grow in human patients. The researchers began by looking at newborn mice. They documented that young mouse healing was due in part to the growth of new collateral arteries into the injured area. Through advanced imaging that let them look at the intact newborn hearts at the cellular level, the researchers showed that this happened because arterial endothelial cells exited the artery, migrated along existing capillaries that extended into injured heart tissue and reassembled to form collateral arteries.

The molecule CXCL12 is an important signal during embryonic development of arterial cells, and has been shown to improve cardiac recovery and function after heart attacks. The scientists wondered if this molecule had a beneficial effect by promoting collateral artery growth in injured heart tissue. They found that CXCL12 was mostly restricted to arterial endothelial cells in uninjured neonatal mouse hearts. In newborn mice with heart injuries, it shows up in the capillaries of the injured area. The researchers found evidence that low oxygen levels in the injured area turned on genes that create CXCL12, signaling the areas to which arterial endothelial cells should migrate.

Next they investigated whether CXCL12 could help adult heart tissue grow collateral arteries. After inducing heart attacks in adult mice, they injected CXCL12 into the injured areas. Sure enough, 15 days after the injuries, there were numerous new collateral arteries formed by the detaching and migrating artery cells. Almost none were present in control mice.


What to Learn from the Debate over Adult Human Neurogenesis?

Neurogenesis is the name given to the processes by which new neurons are created and integrated into neural circuits. More neurogenesis is generally agreed to be beneficial, in the same way as stem cell activity in other tissues is beneficial, by helping to maintain tissue function in the face of injury and biological wear and tear. As is the case for stem cell function in general, neurogenesis falters with age where it is known to occur throughout life. Beyond this point of maintenance, a process common to all tissues, there is also the matter of cognitive function to consider, however. Greater neurogenesis may aid in learning, memory, and other capabilities, distinctly from the role it plays in normal tissue maintenance.

Neurogenesis obviously occurs throughout the brain in early life, as this organ is constructed and finalized. Until the 1990s it was thought that this process ceased in most areas of the brain in adults. Then it was proven that adult neurogenesis does in fact occur in mice, in areas of the brain important to memory and cognition, which was at the time quite the upheaval. Since then near all of the research on this topic has taken place in mice, as it is very challenging to investigate human brain tissue. Nonetheless, the consensus has been that the lessons learned in mice also apply to humans. As a consequence, the goal of artificially increased neurogenesis in older people drives many medical research programs. Scientists seek the foundations for therapies that can slow cognitive decline or produce greater recovery following brain injury, and hope that this can be achieved by adjusting levels of regulatory proteins controlling neurogenesis.

Another upheaval in the matter of adult neurogenesis is underway. This past year has seen a vigorous debate over whether or not the findings in mice do apply to humans. This started with a careful study that found no evidence of adult neurogenesis in our species. It was shortly followed by another careful study that did show evidence of adult neurogenesis. A great deal of commentary on all sides followed these findings. Today's paper is an example of the type, in this case siding with the uncomfortable position that perhaps neither older mice nor humans exhibit meaningful neurogenesis. If this case, this may complicate and delay the advent of any therapies based on spurring neurogenesis in the aged brain.

Lessons learned from the adult neurogenesis debate

Since the 1960s, consensus about whether human adults generate new neurons with age has swayed back and forth from "yes, at least in some places in the brain" to "no, not at all." The debate reignited in 2018 when two headline-grabbing papers, published weeks apart, made convincing arguments for each side. "It's clear that there is a lot of controversy, which to me seems unwarranted because a yes or no for 'is there adult neurogenesis' is a little too simplistic and distracts us from other important questions. It's worth asking if methodological differences are the only reason that some people aren't finding new neurons or if there is some truth to the observations that neurogenesis may be limited with age in humans. I wanted to take a quantitative look at the research and see where it all leads."

One stand-out issue is that labs that find more neurogenesis in mice than in humans are studying it in young mice, while human research is often conducted in adults from middle to old age. In addition, primates and rodents develop most of their neurons at different times in their early development: human neuron populations peak during the first half of gestation, while mouse neurogenesis continues through birth or after birth. So the observation that there is more neurogenesis in mice might also be because the rodent brain develops later in life. "The literature also indicates that if you look at a middle-aged rodent, it doesn't have much neurogenesis either. If we were to study the same in relative-aged human subjects, I don't think the story is much different. For much of the adult lifespan, we're not bursting at the seams with new neurons. While that may be disconcerting for people, it does reconcile the field: it's not that some studies are right and some are wrong."

Recalibrating the Relevance of Adult Neurogenesis

Reports of limited neurogenesis in adult humans have been difficult to reconcile with animal work demonstrating persistent neurogenesis throughout life, and with human studies arguing for lifelong neurogenesis. Our review suggests that, once developmental timing is accounted for, the human and animal literatures are generally consistent with one another: the human hippocampus develops largely prenatally, leaving less opportunity for postnatal neurogenesis. In contrast, the rodent dentate gyrus forms postnatally and is typically studied in adolescence and young adulthood, when neurogenesis rates remain high. Thus, some confusion has arisen as a result of modeling adult humans with juvenile rodents. While it remains unresolved whether neurogenesis drops to zero in adult humans, our comparative analysis suggests that it falls to low rates for much of adult life in all species.

What then is the relevance of adult neurogenesis for humans? First, low rates of neurogenesis in adulthood, over years and decades, may have substantial additive effects that promote long-term health. Second, higher rates in early life may play a significant role in childhood and adolescent brain function, when many mental health disorders originate. Uncertainties about human-animal differences, and the extent to which cellular properties reflect maturational states versus persistent features, also highlight opportunities for future research. In summary, consideration of the broader neurodevelopmental context will help us take advantage of the benefits that neurogenesis may offer for human mental health.

Poor Sleep Causes Raised Levels of Tau in the Brain

Researchers here suggest a possible explanation for the observed association between disrupted sleep in later life and the development and progression of Alzheimer's disease. Sleep appears necessary to clear out tau produced during waking hours, and loss of sleep means raised levels of tau persist. The more tau in circulation, the more that an altered form of tau will be generated and aggregate into neurofibrillary tangles to damage brain cells. More research would be needed to quantify the size of this effect in comparison to, say, the contributions of lack of exercise or obesity. In the long run, however, one would hope that therapies capable of safely and efficiently clearing neurofibrillary tangles will make the whole question of contributions of this nature entirely irrelevant.

Poor sleep has long been linked with Alzheimer's disease, but researchers have understood little about how sleep disruptions drive the disease. Now, studying mice and people, researchers have found that sleep deprivation increases levels of the key Alzheimer's protein tau. And, in follow-up studies in the mice, the research team has shown that sleeplessness accelerates the spread through the brain of toxic clumps of tau ­- a harbinger of brain damage and decisive step along the path to dementia.

Tau is normally found in the brain - even in healthy people - but under certain conditions it can clump together into tangles that injure nearby tissue and presage cognitive decline. Recent research has shown that tau is high in older people who sleep poorly. But it wasn't clear whether lack of sleep was directly forcing tau levels upward, or if the two were associated in some other way. To find out, researchers measured tau levels in mice and people with normal and disrupted sleep. Mice are nocturnal creatures. The researchers found that tau levels in the fluid surrounding brain cells were about twice as high at night, when the animals were more awake and active, than during the day, when the mice dozed more frequently. Disturbing rest during the day caused daytime tau levels to double. Much the same effect was seen in people.

To rule out the possibility that stress or behavioral changes accounted for the changes in tau levels, researchers created genetically modified mice that could be kept awake for hours at a time by injecting them with a harmless compound. Using these mice, the researchers found that staying awake for prolonged periods causes tau levels to rise. Altogether, the findings suggest that tau is routinely released during waking hours by the normal business of thinking and doing, and then this release is decreased during sleep allowing tau to be cleared away. Sleep deprivation interrupts this cycle, allowing tau to build up and making it more likely that the protein will start accumulating into harmful tangles.


An Approach to In Vivo Detection of Senescent Cells

The accumulation of senescent cells is an important cause of aging. These cells are created in large numbers, day in and day out, but near all are quickly destroyed, either by their own programmed cell death processes, or by the immune system. A tiny fraction linger, however, and produce a potent mix of inflammatory signals that disrupt tissue function in many ways. The more senescent cells, the worse the consequences. There are assays to detect senescent cells in tissue samples, but these tests are all quite old and cumbersome, with a limited range of application. The research community would benefit greatly from improved methods of detection of senescent cells, assays capable of greater discrimination, and particularly those that can run in a living animal. The paper noted here is a step in that direction.

Although senescent cells are well-characterized in culture, identifying senescent cells in vivo has been challenging. The inability to reliably identify senescent cells in an intact organism has impaired the study of their precise role in tumor suppression and physiological aging. To date, activation of p16INK4a expression has proven to be one of the most useful in vivo markers of senescence. The expression of p16INK4a is highly dynamic, being largely undetectable in healthy young tissues, but rising sharply in many tissues with aging or after certain sorts of tissue injury. Murine studies suggest that accumulation of p16INK4a leads to an age-related loss of replicative capacity in select tissues, thereby causing some phenotypic aspects of aging.

Our laboratory and others have placed reporter genes under the control of the p16INK4a promoter by either transgenic or knock in approaches. These reporter alleles have been employed to demonstrate that the p16INK4a promoter activity increases during wounding, inflammation, tumorigenesis, or aging in vivo in tissues. While valuable for studies at the tissue or organ level, these alleles have been limited in their ability to detect and isolate individual cells with strong activation of the p16INK4a promoter in vivo. To study individual p16INK4a-activated cells, we have generated a fluorescence-based reporter allele with tandem-dimer Tomato (tdTom) knocked into the endogenous p16INK4a locus. This allele enables the identification and isolation of p16INK4a-activated cells at the single-cell level from cultured cells and in vivo. Using this allele, we quantified tdTom+ cells in several tissues with aging or in the setting of inflammation, and isolated these cells for characterization in terms of function and gene expression.


Continued Exploration of the Mechanisms of Cellular Senescence

Today, a pair of papers that are representative of present interest in the deeper mechanisms of cellular senescence. Senescent cells have of late become a major focus in the aging research community, now that scientists are largely convinced that (a) accumulation of these cells is a significant cause of aging, and (b) removing them can reverse aging and age-related disease to a large enough degree to justify significant investment in further development. Better late than never! The evidence has been compelling for decades, but only in 2011 was sufficient funding raised by a sufficiently well-regard research group to build an animal study of senescent cell clearance that the rest of the scientific community found compelling. This could all have happened ten or twenty years earlier, given different people in charge of budgets and strategies.

Still, here we are now. There is presently something of a gold rush underway in the research and development communities when it comes to the biochemistry of cellular senescence. Even setting aside more direct approaches such as suicide gene therapies or immunotherapies capable of targeting senescent cells for destruction, researchers have discovered at least four plausible mechanisms and associated drug candidates that can intervene in the peculiar biochemistry of these cells in order to nudge them into apoptosis and self-destruction. Companies have been founded to develop small molecule drugs based on a couple of these mechanisms, and hundreds of millions of dollars have been raised for clinical development. There is the sense that any similar new discovery will open the same sort of doors for its discoverers, and the expectation that many more useful mechanisms will be discovered.

Destruction of senescent cells is not the only goal in the research community. Other groups are more interested in preventing senescence from taking place, or in trying to modulate the harmful inflammatory signaling that allows a small number of senescent cells to cause widespread disruption of tissue function. I think that both of these are inferior approaches, because senescence is a mark of damage and why keep damaged cells around on the one hand, and on the other safely altering this poorly understood and diverse cell signaling is a vast, enormously complex project. Nonetheless, there will still be funding readily available for those groups that make discoveries in this field, at least until a few attempts at producing clinical therapies along these lines fail to do as well as the more direct approach of just destroying these unwanted cells. That is the way I expect matters to progress, in any case.

S100A13 promotes senescence-associated secretory phenotype and cellular senescence via modulation of non-classical secretion of IL-1α

Senescent cells display the senescence-associated secretory phenotype (SASP) which plays important roles in cancer, aging, etc. Cell surface-bound IL-1α is a crucial SASP factor and acts as an upstream regulator to induce NF-κB activity and subsequent SASP genes transcription. IL-1α exports to cell surface via S100A13 protein-dependent non-classical secretory pathway. However, the status of this secretory pathway during cellular senescence and its role in cellular senescence remain unknown.

Here, we show that S100A13 is upregulated in various types of cellular senescence. S100A13 overexpression increases cell surface-associated IL-1α level, NF-κB activity, and subsequent multiple SASP genes induction, whereas S100A13 knockdown has an opposite role. We also exhibit that Cu2+ level is elevated during cellular senescence. Lowering Cu2+ level decreases cell surface-bound IL-1α level, NF-κB activity, and SASP production. Further, impairment of the non-classical secretory pathway of IL-1α delays cellular senescence.

D-amino Acid Oxidase Promotes Cellular Senescence via the Production of Reactive Oxygen Species

d-amino acid oxidase (DAO) is a flavin adenine dinucleotide (FAD)-dependent oxidase metabolizing neutral and polar d-amino acids. Unlike l-amino acids, the amounts of d-amino acids in mammalian tissues are extremely low, and therefore, little has been investigated regarding the physiological role of DAO. We have recently identified DAO to be upregulated in cellular senescence, a permanent cell cycle arrest induced by various stresses, such as persistent DNA damage and oxidative stress. Because DAO produces reactive oxygen species (ROS) as byproducts of substrate oxidation and the accumulation of ROS mediates the senescence induction, we explored the relationship between DAO and senescence.

The accumulation of ROS is widely observed in senescence induced by various types of stress. ROS can hasten senescence through induction of oxidative DNA damage, and a recent study has shown that a positive feedback loop between ROS production and DNA damage response establishes senescence with the contribution of p21. Although ROS are reported to mediate p53-dependent cell cycle arrest, the mechanism by which p53 regulates ROS production in the process of senescence induction remains mostly unclear. We have recently identified DAO to be up-regulated specifically in senescent cells and shown the direct transcriptional regulation of DAO by p53.

In the present study, we evaluated the functional association of DAO with the senescence process. We revealed that DAO accelerates senescence via enzymatic generation of ROS and that d-arginine, a substrate for DAO, is abundantly present in cultured cancer cells. DAO is activated in response to DNA damage presumably due to an increase in availability of its coenzyme, FAD.

The Acceleration Years in the Development of Rejuvenation Therapies

The upward curve of technological progress is steepening, and this is particularly the case for the development of medical biotechnologies capable of meaningfully addressing the causes of aging. These are the acceleration years, in which the first rejuvenation therapies exist in prototype form, commercial development begins in earnest, and funding starts to pour into the field. That in turn drives funding into many neighboring areas of fundamental research that have previously struggled, bringing further rejuvenation therapies closer to viability. If you look at the outset of past fields of human scientific endeavor, most are stories of decades, sometimes generations, of painfully slow, unsupported attempts to make progress. Then all of of a sudden, in the course of a decade, the tipping point is reached and an entire industry blossoms into being. We are just about there for rejuvenation biotechnology; it is the end of the lengthy beginning, and the start of a great and energetic new phase of development.

It is customary, in techno-visionary circles, to base one's expectations of the future on the principle of exponentially accelerating change. The often uncannily accurate timeframe predictions of Ray Kurzweil have engendered a culture of thinking and talking in exponential terms, even when it comes to the names of conferences. Like any one-word meme, this does not tell the whole story: some aspects of technological progress pretty clearly don't proceed exponentially, and indeed some (which, mercifully, include the rate of progress necessary to maintain longevity escape velocity once we reach it) don't need to be exponential in order to achieve needed goals. But today I want to highlight the opposite phenomenon: phases during a technology's development when progress is genuinely superexponential, as with the sudden acceleration in 2007 or so in the amount of DNA that could be sequenced for a given price.

Inevitably, my sense that rejuvenation biotechnology has had a bona fide superexponential year is to a large extent subjective. However, my location at the eye of this storm gives me some basis for feeling that I'm probably basing it on good information. What is that information?

The single biggest item is the truly breathtaking rate of proliferation of private-sector involvement in this space. That proliferation has been manifest on both sides of the fence - in the number of startups seeking investment, and equally in the number of investors seeking opportunities to get involved. A comparison with the situation just twelve months ago can be made in many ways, but for me the most straightforward is the task of organizing a one-day investor-facing event in early January in San Francisco on behalf of my friends at Juvenescence. In 2018, the task of identifying a dozen companies to showcase was easy for me - that was pretty much the total number of startups I knew of in the rejuvenation space that were in a fundraising mode, and I was pretty sure that not many others existed below my radar. But I'm engaged right now in organizing the same thing for January 2019, and the situation could not be more different. Even when restricting my attention to companies located in this part of the world, I am swamped with high-quality options; and literally not a week goes by any more when I don't become aware of another one. The takeoff has been as spectacular as for the dotcom boom.

What of the other side of the fence, the investors? There the story is just as bright. A year ago, I could count the investors who were overtly focusing much, and in some cases most, of their attention on the rejuvenation space on the fingers of two hands. Now, it is no exaggeration to say that I have lost count: every single conference I speak at (and that's more than one a week on average) I am approached by an investor who is eager to learn more about how to get involved. The acceleration is staggering. The dotcom boom is again the natural comparison, and again I think the trajectory is similar.


The Epigenetic Clock Does Not Reflect Long-Term Physical Activity Differences in Twins

Epigenetic clocks are a weighted algorithmic combination of specific DNA methylation markers, those that exhibit characteristic changes with age. The various iterations of the clock have a strong association with chronological age, and appear to reflect biological age as well, in that people with more pronounced age-related disease and populations with higher mortality rates tend to have a higher epigenetic age than their healthier peers. Since the clock was reverse engineered by analysis of DNA methylation and age data, there remains the question of what exactly it is measuring. There is no comprehensive map to definitively link changes in epigenetic markers with the progression of the causes of aging.

Thus it is presently hard for researchers to make good use of the clock in speeding up the development of potential rejuvenation therapies; given a result, there will be uncertainty over what the result means. Numerous studies have been carried out on the epigenetic clock and specific medical conditions and therapies. Some of the results are troubling, such as the one here. If one can take twins who have a lifetime of very different exercise habits behind them, and find that they have roughly the same epigenetic age, that is a challenge. The epidemiological and animal data on exercise, even the modest levels of physical activity discussed here, strongly indicates that it has a robust, measurable effect on mortality rate and risk of age-related disease. If that doesn't show up in the epigenetic clock, we must come back once again to ask just what is it that the clock measures.

Advances in the fields of molecular biology have produced novel promising candidate biomarkers and their combinations that may be considered as biological aging clocks. So far, one of the most promising new aging clocks is DNA methylation (DNAm) age, also known as the "epigenetic clock". DNAm age is a multi-tissue age estimate based on DNA methylation at 353 specific age-related CpG sites. It is determined with a special algorithm, which is publicly available. The epigenetic clock appears to be associated with a wide spectrum of aging outcomes, most consistently mortality. Discrepancy between DNAm age and chronological age, i.e., higher "age acceleration" predicts all-cause mortality.

So far, it is also not clear whether the genetic component in variation of DNAm age changes over a life span. On the other hand, some environmental exposures and behaviors such as infections, diet, alcohol use, smoking, and work exposures predispose to age-related diseases and increase probability of death. Only part of individual variation to life expectancy can be accounted for using known and measured characteristics and exposure. An epigenetic clock could provide insights into the mechanisms behind why some individuals age faster than others and are more prone to age-related diseases and accelerated decline in physical function.

Physical activity is a potentially modifiable behavior that could slow down the rate of cellular and molecular damage accumulation and blunt the decline in physiological function with increasing age. The purpose of the study was to estimate the magnitude of genetic and environmental factors affecting variation in DNAm-based age acceleration in young and older monozygotic (MZ) and dizygotic (DZ) twins with a focus on leisure time physical activity.

The relative contribution of non-shared environmental factors was larger among older compared with younger twin pairs [47% versus 26%]. Correspondingly, genetic variation accounted for less of the variance in older compared with younger pairs [53% versus 74%]. We tested the hypothesis that leisure time physical activity is one of the non-shared environmental factors that affect epigenetic aging. A co-twin control analysis with older same-sex twin pairs (seven MZ and nine DZ pairs, mean age 60.4 years) who had persistent discordance in physical activity for 32 years according to reported/interviewed physical-activity data showed no differences among active and inactive co-twins, DNAm age being 60.7 vs. 61.8 years, respectively. Results from the younger cohort of twins supported findings that leisure time physical activity is not associated with DNAm age acceleration.


Towards Reliable, Low-Cost Tests for the Earliest Stages of Alzheimer's Disease

The research community has moved quite determinedly these past few years towards practical, low-cost tests for early Alzheimer's disease. Even with the limited means available to patients today, an early warning might be used to delay the aggregation of amyloid-β that takes place in the initial stages of the condition, before the appearance of cognitive impairment. Lifestyle changes such as weight loss and improved fitness, antiviral therapies, and control of chronic inflammation should all make some difference, given what is known of the mechanisms of Alzheimer's disease. Looking ahead, better options may soon be available. Senolytics, for example, may make a difference. Further, as means of directly reducing amyloid-β levels in the aging brain are starting to emerge, finally, these therapies might be better applied in the early stages of the condition, rather than later, when the disease process is beyond their ability to control.

Early treatment through the clinical community requires some form of early diagnosis - so early treatment is very dependent on the existence of standard, widely accepted tests that can be readily and cheaply applied. While it is certainly possible to assess amyloid-β in cerebrospinal fluid, and has been for many years, that requires a lumbar puncture. It is expensive, painful, and certainly not the sort of thing people would willingly undergo once a year. Today's selection of research results from recent months covers a number of lines of work in which researchers are making progress towards an improved set of tests that might determine progression towards Alzheimer's disease.

Blood test detects Alzheimer's damage before symptoms

A simple blood test reliably detects signs of brain damage in people on the path to developing Alzheimer's disease - even before they show signs of confusion and memory loss. The test detects neurofilament light chain, a structural protein that forms part of the internal skeleton of neurons. When brain neurons are damaged or dying, the protein leaks out into the cerebrospinal fluid that bathes the brain and spinal cord and from there, into the bloodstream.

Finding high levels of the protein in a person's cerebrospinal fluid has been shown to provide strong evidence that some of their brain cells have been damaged. But obtaining cerebrospinal fluid requires a spinal tap, which many people are reluctant to undergo. Here, researchers studied whether levels of the protein in blood also reflect neurological damage. To find out whether protein blood levels could be used to predict cognitive decline, the researchers collected data on 39 people with disease-causing variants when they returned to the clinic an average of two years after their last visit. The researchers found that people whose blood protein levels had previously risen rapidly were most likely to show signs of brain atrophy and diminished cognitive abilities when they revisited the clinic. "It will be important to confirm our findings in late-onset Alzheimer´s disease and to define the time period over which neurofilament changes have to be assessed for optimal clinical predictability."

New discoveries predict ability to forecast dementia from single molecule

A new study shows that harmful single tau molecules take different shapes that each correlates to a distinct type of larger assembly that will form and self-replicate across the brain. Researchers had already established that the structure of larger tau assemblies determines which type of dementia will occur - which regions of the brain will be affected and how quickly the disease will spread. But it was unknown what specified these larger structures. The new research reveals how a single tau molecule that changes shape at the beginning of the disease process contains the information that determines the configuration of the larger, toxic assemblies. This finding suggests that characterization of the conformation of single tau molecules could predict what incipient disease is occurring - Alzheimer's or other types of dementia.

The team is trying to translate these findings into clinical tests that examine a patient's blood or spinal fluid to detect the first biological signs of the abnormal tau, before the symptoms of memory loss and cognitive decline become apparent. The researchers are also working to develop treatments to stabilize shape-shifting tau molecules, prevent them from assembling, or promote their clearance from the brain.

A biomarker in the brain's circulation system may be Alzheimer's earliest warning

The blood-brain barrier is a filtration system, letting in good things (glucose, amino acids) and keeping out bad things (viruses, bacteria, blood). It's mostly comprised of endothelial cells lining the 400 miles of arteries, veins, and capillaries that feed our brains. Some evidence indicates that leaks in the blood-brain barrier may allow a protein called amyloid into the brain where it sticks to neurons. This triggers the accumulation of more amyloid, which eventually overwhelms and kills brain cells.

"Cognitive impairment, and accumulation in the brain of the abnormal proteins amyloid and tau, are what we currently rely upon to diagnose Alzheimer's disease, but blood-brain barrier breakdown and cerebral blood flow changes can be seen much earlier. This shows why healthy blood vessels are so important for normal brain functioning." Blood-brain barrier leaks can be detected with an intravenously administered contrast substance in concert with magnetic resonance imaging. Brain microbleeds, another sign of leakage, also can be picked up with MRI. A slowdown in the brain's uptake of glucose, visible via PET scan, can be a another result of blood-brain barrier breakdown.

Scientists pave the way for saliva test for Alzheimer's disease

Researchers examined saliva samples from three sets of patients, those with Alzheimer's disease, those with mild cognitive impairment, and those with normal cognition. Using a powerful mass spectrometer, they examined more than 6,000 metabolites - compounds that are part of our body's metabolic processes - to identify any changes or signatures between groups. "In this analysis, we found three metabolites that can be used to differentiate between these three groups. This is preliminary work, because we've used a very small sample size. But the results are very promising. If we can use a larger set of samples, we can validate our findings and develop a saliva test of Alzheimer's disease. So far, no disease-altering interventions for Alzheimer's disease have been successful. For this reason, researchers are aiming to discover the earliest signals of the disease so that prevention protocols can be implemented."

An Odd Result on Height and Life Span from a Recent Epidemiological Study

The present consensus in the research community is that taller people have shorter life spans. If nothing else, more height means more cells and thus greater odds of a cancerous combination of mutations turning up. But given that taller people also exhibit a notably higher risk of numerous other age-related conditions, there is more to it than that. Given this context, the results from the recent study here are somewhat odd, finding that taller women have greater odds of survival in later life. I'd be inclined to write this off to an artifact in the study population or design until such time as other researchers replicate the results.

Previous research has looked at the associations between weight (BMI, body mass index), physical activity, and reaching old age, but most studies have combined both sexes, or focused exclusively on men. Women and men's lifespans differ, which may be influenced by factors such as hormones, genes, and/or lifestyle. To explore these differences further, the researchers analysed data from the Netherlands Cohort Study (NLCS), which included more than 120,000 men and women aged between 55 and 69 when it began in 1986. They wanted to see if there were any links between height, weight, leisure time physical activity, and the likelihood of reaching the age of 90, and if there were any differences between men and women.

Some 7807 participants (3646 men and 4161 women aged between 68 and 70) provided detailed information in 1986 on their current weight, height, weight when aged 20, and their leisure time physical activity. This included activities such as gardening, dog walking, DIY (home improvements), walking or cycling to work, and recreational sports, which were grouped into categories of daily quotas: less than 30 minutes; 30 to 60 minutes; and 90 minutes or more.Participants were then monitored until death or the age of 90, whichever came first.

Some 433 men (16.7%) and 944 women (34.4%) survived to the age of 90. Women who were still alive by this age were, on average taller, had weighed less at the start of the study, and had put on less weight since the age of 20 than those who were shorter and heavier. What's more, women who were more than 175 cm (5 feet 9 inches) in height were 31 per cent more likely to reach 90 than women less than 160 cm ( 5 feet 3 inches). No such associations were seen among the men.

When it came to physical activity levels, men who clocked up over 90 minutes a day were 39 per cent more likely to reach 90 than those who did less than 30 minutes. And every extra 30 minutes of daily physical activity they racked up was associated with a 5 per cent increase in their chances of turning 90. But this wasn't the case for women. Those who chalked up more than 30-60 minutes a day were 21 per cent more likely to reach 90 than those managing 30 minutes or less. But there seemed to be an optimal threshold for women: around 60 minutes a day was associated with the best chance of their celebrating a 90th birthday.


Gum Disease Bacteria Again Linked to Alzheimer's Disease

Gum disease is linked to the development of age-related conditions, particularly cardiovascular disease and neurodegenerative conditions such as Alzheimer's disease. There is a noted association between gum disease and overall mortality rates in late life. One possibility is that this relationship arises due to inflammation, with gum disease (and the bacteria that cause it) acting to boost levels of inflammation. Greater inflammation in turn accelerates the progression of a range of age-related conditions, from atherosclerosis to cognitive decline. There may be more to it than that, however. The research here suggests that other activities of the bacteria involved in gum disease may be as important, and development of a first attempt at a therapy targeting these bacteria is well underway.

Although infectious agents have been implicated in the development and progression of Alzheimer's disease (AD), the evidence of causation hasn't been convincing. In a new study in animal models, oral Porphyromonas gingivalis (Pg) infection led to brain colonization and increased production of amyloid beta (Aβ), a component of the amyloid plaques commonly associated with AD. The study team also found the organism's toxic enzymes, or gingipains, in the neurons of patients with AD. Gingipains are secreted and transported to outer bacterial membrane surfaces and have been shown to mediate the toxicity of Pg in a variety of cells. The team correlated the gingipain levels with pathology related to two markers: tau, a protein needed for normal neuronal function, and ubiquitin, a small protein tag that marks damaged proteins.

Seeking to block Pg-driven neurotoxicity, Cortexyme set out to design a series of small molecule therapies targeting Pg gingipains. In preclinical experiments, researchers demonstrated that by inhibiting the compound COR388, there was reduced bacterial load of an established Pg brain infection, blocked Aβ42 production, reduced neuroinflammation, and protected neurons in the hippocampus - the part of the brain that mediates memory and frequently atrophies early in the development of AD. In October 2018, Cortexyme announced results from its Phase 1b clinical trial of COR388. COR388 showed positive trends across several cognitive tests in patients suffering from AD, and Cortexyme plans to initiate a Phase 2 and 3 clinical trial of COR388 in mild to moderate AD in 2019.


Effective Altruism and Effective Research for Human Longevity

The effective altruism movement is a good example of the sort of thing that can only arise in the modern information-rich environment of easily available data and cheap communication. It is half a reaction against the waste, fraud, and general ineffectiveness that characterizes all too much large-scale philanthropy, and half a chance to meaningfully reexamine what everyday philanthropy can look like in an age of greater communication and knowledge. It is easy to salve the conscience by donating to a group that one believes are going to do good, and most people go no further than this. That allows charities to become inefficient and self-serving, and in the worst cases results in organizations that have become symbiotic with the problem they are allegedly solving, and supporting them actually makes matters worse. Is it possible, with minimal additional effort, to do better than feeling good as an individual and actually donate in ways that achieve good in the world? The effective altruists would like to pave the way to make that possible for everyone.

When it comes to human aging, one doesn't have to run the numbers all that rigorously to determine that more suffering and death is produced by aging than by any other single cause. Aging is something like 600 times worse than malaria for the human race, for example, when only considering mortality. It is probably worse than that when also considering disability and duration of suffering. From the point of view of whether or not something is a glaring problem that we should all devote a little time to helping with, it doesn't much matter whether aging is 100 or 1000 times worse than malaria: either case should be a clarion call to action. Yet people don't think much on the topic of doing something about aging, even though most are generally supportive of research into treatments for specific manifestations of age-related disease.

I suspect that most people who debate the numbers are somewhat skeptical of the prospect for increasing human life span. Near all modern medicine for age-related diseases introduced over recent decades produces gains of just a few years of additional life expectancy at most. Exercise does just as well, spread over a lifespan. When the choice is between spending funds to gain a few years for older people or spending funds to improve quality of life for younger people, the philanthropic institutions of the world have tended to bias strongly towards the latter option. Fair enough. But the technology has advanced. It is no longer about determinedly wrestling with the inexorable damage of aging to gain a few extra months of life expectancy for someone with a low quality of life. Rejuvenation therapies will produce large and ever-increasing gains in health and life expectancy for older individuals, where "large" will soon enough mean additional decades of healthy life.

Still, comparatively few lines of research into human aging and longevity have the prospect of leading to rejuvenation. Many are marginal. So effective altruism aimed at bringing aging under medical control and producing very large gains in life span depends upon effective research and development. This means choosing the right strategies to support, those based on repairing the damage that causes aging, rather than those that try to paper over or compensate for the damage in some way. It is very hard to keep a damaged machine running when repair is not on the table, and this has been well demonstrated in medical progress and practice over the second half of the 20th century. Gains were small and hard-won, precisely because the wrong strategies were applied to the treatment of aging. Researchers attempted to treat the end stage symptoms rather than repairing the cell and tissue damage that lies at the root of all age-related disease.

These two articles from groups considering the reinvention of philanthropy are interesting to contrast on this basis. One sees the potential for very large gains in life span, and a control over disease and disability, while the other does not. Evidently, this makes a large difference to the calculus of efficiency when considering whether or not to support research into human aging.

A general framework for evaluating aging research. Part 1: reasoning with Longevity Escape Velocity

Longevity Escape Velocity (LEV) is the minimum rate of medical progress such that individual life expectancy is raised by at least one year per year if medical interventions are used. This does not refer to life expectancy at birth; it refers to life expectancy calculated from a person's statistical risk of dying at any given time. This is equivalent to saying that a person's expected future lifetime remains constant despite the passing years. It's possible, given sufficient ongoing improvement of medicine and its democratisation, that nearly everyone on the planet, at a certain date in the future, will benefit from therapies that allow Longevity Escape Velocity to be attained, at least until aging is eradicated completely.

If a given intervention "saves a life", this usually means that it averts 30 to 80 Disability-Adjusted Life Years (DALYs). This figure comes up from the remaining life expectancy of the recipients of the intervention. In order to evaluate the impact of aging research, one could be tempted to try to estimate how many end-of-life DALYs that a possible intervention resulting from the research could save and adjust the number using the probability of success of the research.

This line of reasoning is part of the impact, and it has to be factored in, but it doesn't consider where the largest impact of aging research is: making the date of Longevity Escape Velocity come closer. This would have the effect of saving many lives from death due to age-related decline and disease, but here, "a life" means, more or less, 1000 Quality-Adjusted Life Years (QALYs). The average lifespan of a person who reached LEV will be around 1000 years, mostly without disability, as 1/1000 is more or less the current risk of death of someone between 20 and 30 years old.

Open Philanthropy: Mechanisms of Aging

We are highly uncertain about, and do not have internal consensus regarding, the potential extension in healthy lifespan that might result if one or two of the present major objectives in anti-aging research were accomplished. Some of us see several years of healthy life extension as the plausible potential upside and others see larger possible gains, but all of us involved in creating this report expect that any increase in healthy lifespan would keep average lifespan within the range of natural lifespans observed in humans today (barring a historically exceptional increase in the rate of scientific progress).

We think the best case for this cause involves the prospect of healthy life extension within the range that some humans currently live. In contrast, some people who are interested in the mechanisms of aging have promoted the idea of "curing" aging entirely. Our default view is that death and impairment from "normal aging" are undesirable. However, we would have some concerns about indefinite life extension, mainly related to entrenchment of power and culture. We don't have internal consensus on whether, and to what extent, such indefinite life extension would be desirable, and don't consider it highly relevant to this write-up. We don't see promising life science research that would result in indefinite life extension in the next few decades, barring a historically exceptional increase in the rate of scientific progress.

Our program officer offers the following forecast to make the above more precise/accountable: By January 1, 2067, there will be no collection of medical interventions for adults that are healthy apart from normal aging, which, according to conventional wisdom in the medical community, have been shown to increase the average lifespan of such adults by at least 25 years, compared with not taking the interventions.

Sequencing Giant Tortoise Genomes in Search of Determinants of Longevity

Sequencing notably long-lived species has produced a number of interesting findings regarding the large variations in longevity between species. Long-lived species tend to exhibit one or more of exceptional DNA repair, exceptional cancer suppression mechanisms, exceptional regenerative and tissue maintenance capacity, exceptional control over inflammation, or the like. This short list is probably just scratching the surface, even given the great diversity of specific mechanisms in each category. For each of these discovered mechanisms it remains a question mark as to whether or not there is any way to safely port them over to humans, or whether they merely offer pointers to the areas of our biochemistry that researchers might prioritize when it comes to the development of rejuvenation therapies.

Comparative genomic analyses leverage the mechanisms of natural selection to find genes and biochemical pathways related to complex traits and processes. Multiple works have used these techniques with the genomes of long-lived mammals to shed light on the signalling and metabolic networks that might play a role in regulating age-related conditions. Similar studies on unrelated longevous organisms might unveil novel evolutionary strategies and genetic determinants of ageing in different environments. In this regard, giant tortoises constitute one of the few groups of vertebrates with an exceptional longevity: in excess of 100 years according to some estimates.

In this manuscript, we report the genomic sequencing and comparative genomic analysis of two long-lived giant tortoises: Lonesome George - the last representative of Chelonoidis abingdonii, endemic to the island of Pinta (Galapagos Islands, Ecuador) - and an individual of Aldabrachelys gigantea, endemic to the Aldabra Atoll and the only extant species of giant tortoises in the Indian Ocean. Comparison of these genomes with those of related species, using both unsupervised and supervised analyses, led us to detect lineage-specific variants affecting DNA repair genes, inflammatory mediators, and genes related to cancer development. Our study also hints at specific evolutionary strategies linked to increased lifespan, and expands our understanding of the genomic determinants of ageing.

This analysis singled out 43 genes with evidence of giant-tortoise-specific positive selection. This list includes genes with known roles in the dynamics of the tubulin cytoskeleton (TUBE1 and TUBG1) and intracellular vesicle trafficking (VPS35). Importantly, the analysis of genes showing evidence of positive selection also includes AHSG and FGF19, whose expression levels have been linked to successful ageing in humans. The list of genes with signatures of positive selection also features TDO2, whose inhibition has been proposed to protect against age-related diseases through regulation of tryptophan-mediated proteostasis. In addition, we found evidence for positive selection affecting several genes involved in immune system modulation, such as MVK, IRAK1BP1, and IL1R2. Taken together, these results identify proteostasis, metabolism regulation and immune response as key processes during the evolution of giant tortoises via effects on longevity and resistance to infection.

An important trait of large, long-lived vertebrates is their need for tighter cancer protection mechanisms, as illustrated by Peto's paradox. Therefore, we analysed more than 400 genes classified in a well-established census of cancer genes as oncogenes and tumour suppressors. We found that several putative tumour suppressors are expanded in turtles compared with other vertebrates. In addition, expansion of PRF1, together with the tortoise-specific duplication of PRDM1, suggests that immunosurveillance may be enhanced in turtles. Taken together, these results suggest that multiple gene copy-number alterations may have influenced the mechanisms of spontaneous tumour growth. Nevertheless, further studies are needed to evaluate the genomic determinants of putative giant-tortoise-specific cancer mechanisms.


Improving Efforts to Bypass the CD47 "Don't Eat Me" Marker Employed by Cancers

Cancers evolve to hide from or co-opt the immune system in a range of ways, some more successfully than others. Since one of the primary tasks of the immune system is to destroy cancerous cells, all cancers must defeat immune surveillance mechanisms to at least some degree. One strategy common to a large faction of cancers is use of CD47, a cell surface feature that the immune cells called macrophages treat as a "don't eat me" signal. In recent years researchers have made considerable progress on a range of ways to interfere with CD47 recognition in macrophages, freeing them to attack cancerous cells with vigor. This latest work builds on that foundation, improving the understanding of the underlying processes, and introducing a new way to take best advantage of sabotage of the CD47 mechanism.

Macrophages are immune cells just like T cells and B cells, but differ in that they can eat cells that are not supposed to be in the body. In fact, they are the most prominent immune cell found in cancer, but unfortunately, most are often convinced to help cancer grow and spread. Cancer cells frequently stop macrophages from attacking them by expressing CD47, a "don't eat me" signal. Researchers now say that merely blocking inhibitory signals like CD47 is not always sufficient to convince macrophages to attack cancer. Instead, two signals are required. First, they need a signal to activate them - such as a toll-like receptor agonist. After that, a second signal - such as a CD47 inhibitor - can lower the threshold needed to wage battle on the cancer.

The team used this approach by activating macrophages with CpG, a toll-like receptor agonist that sends the first signal, and found that it rapidly induced shrinkage of tumors and prolonged survival of mice even without the requirement of T cells. Unexpectedly, they also found that the activated macrophages were able to eat cancer cells even in the presence of high levels of CD47.

To understand the molecular basis of this phenomenon, the team traced the metabolic activity of macrophages and determined that activated macrophages began to utilize both glutamine and glucose as fuel to support the energy requirements needed for them to eat cancer cells. This rewiring of the macrophages metabolism was necessary for CpG to be effective, and the researchers say these findings point to the importance of macrophage metabolism in determining the outcome of an immune response. "It is the metabolism that ultimately allows macrophages to override signals telling them not to do their job."


Researchers Demonstrate the Use of Thymus Organoids to Generate T Cells from Induced Pluripotent Stem Cells

One of the potential approaches to ameliorate the age-related failure of the immune system is to periodically inject competent T cells in large numbers. This could compensate to some degree for the greatly diminished rate at which new T cells are created in older individuals. For what it is worth, I think there are much better approaches, but this one is arguably closer to feasibility. Nonetheless, the goal isn't as easy to accomplish as it is to describe. The mix of T cell types must be appropriate, roughly the same as is generated naturally in young people. The T cells must go through a complex multi-stage process of maturation, to gain self-tolerance and correct function. This maturation occurs in the thymus, an organ that atrophies in old age, so while it has been possible for years now to generate immature T cells, called thymocytes, from patient-matched induced pluripotent stem cells, injecting them into the body would run right into the problem of a run-down and poorly functional thymus.

In the research results I'll point out today, scientists demonstrate that thymus tissue grown outside the body can be used to mature T cells in volume. That means that patient-matched T cells for therapy in arbitrary numbers are a feasible goal. Generate induced pluripotent stem cells from a patient skin sample, then build thymus organoids from that starting point. Lastly run thymocytes produced from the same induced pluripotent stem cells through the organoids. The output is a supply of functional patient-matched T cells, though as noted, there are still problems to be ironed out.

Patient-matched cells for any use are an expensive prospect, however. Present therapies with this requirement are among the most costly of any modern medicine. Further, they require a great deal of time to deploy. Months can pass between obtaining an initial patient tissue sample and the readiness of cells for therapy. A major focus for the research community is to find ways, wherever possible, to create universal cell lines. A universal cell line centralizes all of the hard work, and the therapies that employ it can thus be much less costly, and more rapidly deployed. This is a plausible goal for immune cells, where the adjustments required to render them non-patient-specific are fairly well understood.

As an additional thought on this topic, it is worth noting that Lygenesis is in the business of developing therapies based on the implantation of thymus organoids into lymph nodes. This has been demonstrated to restore the natural supply of T cells in animal models. Given that project, using thymus organoids to produce patient-matched T cells seems unnecessarily convoluted. Expensive or not, it is an extra step that isn't needed, provided that the Lygenesis approach can be made to work in humans reliably enough to get past the regulatory gauntlet.

Scientists create a renewable source of cancer-fighting T cells

T cell therapies, including CAR T-cell therapy, have shown great promise for treating certain types of cancer. Current approaches involve collecting T cells from a patient, genetically engineering the T cells with a receptor that helps them recognize and destroy cancer cells, and then infusing the cells back into the patient. But engineered T cells do not always function well, treatment is expensive because it is tailored to each patient, and some people with cancer don't have enough T cells to undergo the therapy. Therefore, a technique that produces T cells without relying on collecting them from patients is an important step toward making T cell therapies more accessible, affordable and effective.

Other researchers have been only partially successful in their attempts to generate T cells using methods that involve combining pluripotent stem cells with a layer of supporting cells. But the T cells produced in those previous studies did not mature to become fully functional T cells. However, it was demonstrated that the 3D structure of an artificial thymic organoid allowed mature T cells to develop from adult blood stem cells. A new study now demonstrates the use of such organoids to coax pluripotent stem cells - which can give rise to every cell type in the body and which can be grown indefinitely in the lab - into becoming mature T cells capable of killing tumor cells.

The research demonstrated that artificial thymic organoids can efficiently make mature T cells from both kinds of pluripotent stem cells currently used in research: embryonic stem cells, which originate from donated embryos, and induced pluripotent stem cells, which are created by reprogramming adult skin or blood cells back to an embryonic-like state. The researchers also showed they could genetically engineer pluripotent stem cells to express a cancer-targeting T cell receptor and, using artificial thymic organoids, generate T cells capable of targeting and killing tumor cells in mice.

Organoid-Induced Differentiation of Conventional T Cells from Human Pluripotent Stem Cells

Engineered T cell therapies hold promise for the effective treatment of cancer and chronic viral infections. The ability to generate T cells on demand from self-renewing human pluripotent stem cells (PSC) may substantially advance the cell therapy field by permitting production of universal-donor T cells from stably gene-modified PSC lines. Although protocols to differentiate PSC into essentially any non-hematopoietic or hematopoietic lineage have been extensively reported, generation of fully functional mature T cells that resemble their adult counterparts has been more problematic. Differentiation of T cells from human PSCs has been limited on two fronts: the ability to specify hematopoietic progenitor cells with T-lineage potential, and the capacity of existing methods to support the positive selection and maturation of T-lineage committed precursors to conventional, naive T cells.

We recently reported that a three-dimensional (3D) artificial thymic organoid (ATO) culture system permits in vitro differentiation of human HSPCs to functional, mature T cells using a standardized Notch ligand-expressing stromal cell line in serum-free conditions. Notably, we observed that both the medium and the 3D structure were critical. We report here that a modified ATO system (PSC-ATO) permits the differentiation of human embryonic stem cell (ESC) and induced pluripotent stem cell (iPSC)-derived human embryonic mesodermal progenitors (hEMPs) to mature, conventional T cells in vitro.

Past Progress Towards Control of Cancer Has Been Slow, Steady, and Incremental

Mortality rates for cancer have diminished slowly and steadily over the past few decades. This is a matter of prevention on the one hand and improvements in early detection of cancer on the other. When caught early enough, even comparatively crude approaches to therapy have a decent chance of controlling and eliminating the cancer. This trend will no doubt continue, but the more rapid, more effective progress that we'd like to see will only emerge given the advent of universal cancer therapies, those that strike at mechanisms, such as telomere lengthening, that are shared by many or all cancers. That is a plausible goal for the decades ahead, but is still a minority position in the research community.

The death rate from cancer in the US has declined steadily over the past 25 years. As of 2016, the cancer death rate for men and women combined had fallen 27% from its peak in 1991. This decline translates to about 1.5% per year and more than 2.6 million deaths avoided between 1991 and 2016. The drop in cancer mortality is mostly due to steady reductions in smoking and advances in early detection and treatment. A total of 1,762,450 new cancer cases and 606,880 deaths from cancer are expected to occur in the US in 2019. During the most recent decade of available data (2006 - 2015), the rate of new cancer diagnoses decreased by about 2% per year in men and stayed about the same in women. The cancer death rate (2007 - 2016) declined by 1.4% per year in women and 1.8% per year in men.

The most common cancers diagnosed in men are prostate, lung, and colorectal cancers. Together, they account for 42% of all cases in men, with prostate cancer alone accounting for nearly 1 in 5 new cases. For women, the 3 most common cancers are breast, lung, and colorectal. Together, they account for one-half of all cases, with breast cancer alone accounting for 30% of new cases. These cancers also account for the greatest numbers of cancer deaths. One-quarter of all cancer deaths are due to lung cancer.

Lung cancer death rates declined 48% from 1990 to 2016 among men and 23% from 2002 to 2016 among women. From 2011 to 2015, the rates of new lung cancer cases dropped by 3% per year in men and 1.5% per year in women. The differences reflect historical patterns in tobacco use. Breast cancer death rates declined 40% from 1989 to 2016 among women. The progress is attributed to improvements in early detection. Colorectal cancer death rates declined 53% from 1970 to 2016 among men and women because of increased screening and improvements in treatment.

Adults ages 85 and older represent the fastest-growing population group in the US. The group's numbers are expected to nearly triple from 6.4 million in 2016 to 19 million by 2060. Cancer risk increases with age, and the rapidly growing older population will increase demand for cancer care. People ages 85 and older represent 8% of all new cancer diagnoses, translating to about 140,690 cases in 2019. Cancer is the second-leading cause of death in the oldest old, following heart disease. 103,250 cancer deaths among this age group are expected in 2019, accounting for 17% of all cancer deaths. As of January 1, 2019, an estimated 1,944,280 people ages 85 and older were cancer survivors, representing 1/3 of all the men and 1/4 of all the women in this age group. They are the fastest-growing group of cancer survivors. Among adults age 85 with no history of cancer, the risk of a cancer diagnosis in their remaining lifetime is 16.4% for men and 12.8% for women.


Clearance of Senescent Cells as a Treatment for Osteoporosis

Senescent cells accumulate with age throughout the body. While only present in comparatively small numbers, even in very late life, their potent inflammatory signaling actively maintains a damaged, dysfunctional state in tissues and the body as a whole. Removing them dampens chronic inflammation and restores regenerative capacity. In animal studies senolytic therapies capable of removing 25-50% of senescent cells in at least some tissues are proving to be a more effective therapy than any presently available option for a wide range of age-related conditions. One example, noted here, is the characteristic loss of bone density with age known as osteoporosis. This is partially a consequence of inflammation, as inflammation disrupts the balance between osteoblasts that create bone and osteoclasts that break down bone. Both types of cell are constantly active in bone tissue, but the balance tips too far towards osteoclasts in the damaged tissue environment of later life.

Cellular senescence refers to a process induced by various types of stress that causes irreversible cell cycle arrest and distinct cellular alterations, including profound changes in gene expression, metabolism, and chromatin organization as well as activation/reinforcement of anti-apoptotic pathways and development of a pro-inflammatory secretome or senescence-associated secretory phenotype (SASP). However, because of challenges and technical limitations in identifying and characterizing senescent cells in living organisms, only recently have some of the diverse in vivo roles of these unique cells been discovered.

New findings indicate that senescent cells and their SASP can have acute beneficial functions, such as in tissue regeneration and wound healing. However, in contrast, when senescent cells accumulate in excess chronically at sites of pathology or in old tissues they drive multiple age-associated chronic diseases. Senotherapeutics that selectively eliminate senescent cells ("senolytics") or inhibit their detrimental SASP ("senomorphics") have been developed and tested in aged preclinical models. These studies have established that targeting senescence is a powerful anti-aging strategy to improve "healthspan" - i.e., the healthy period of life free of chronic disease.

The roles of senescence in mediating age-related bone loss have been a recent focus of rigorous investigation. Studies in mice and humans demonstrate that with aging, at least a subset of most cell types in the bone microenvironment become senescent and develop a heterogeneous SASP. Furthermore, age-related bone loss can be alleviated in old mice, with apparent advantages over anti-resorptive therapy, by reducing the senescent cell burden genetically or pharmacologically with the first class of senolytics or a senomorphic. Collectively, these findings point to targeting senescence as a transformational strategy to extend healthspan, therefore providing strong rationale for identifying and optimizing senotherapeutics to alleviate multiple chronic diseases of aging, including osteoporosis, and set the stage for translating senotherapeutics to humans, with clinical trials currently ongoing.


A Recent Update on the Use of Immune Ablation and HSCT to Treat Autoimmunity

For more than twenty years now, Richard Burt's research teams have been working on the treatment of autoimmunity through the destruction and recreation of the immune system. Autoimmunity is a malfunction in the self-tolerance of immune cells, leading them to attack patient tissues. The malfunction is entirely contained in the immune system, so if the immune system is destroyed and replaced, the autoimmunity stops. If the genesis of autoimmunity is happenstance, an unfortunate one-time accident, then this is a cure. But if autoimmunity has a trigger outside the immune system in a given patient, it will return after some period of time.

The major autoimmune conditions are not well enough understood to be able to confidently point at specific causes. Some are clearly still umbrella categories, descriptions of symptoms and end states waiting to be split apart into a better taxonomy of disease based on underlying causes. It is not possible to make sensible statements as to the degree to which any given condition falls into one or other of the categories above, a one-time accident versus a continued triggering cause. We can only make educated guesses. In the ten years since Burt's group carried out a trial of immune destruction and recreation in type 1 diabetes patients, the data has shown that remission from the condition lasted a median 3.5 years. Thus type 1 diabetes appears largely a condition that has a lasting trigger. Or, we could argue that the approach used at the time failed to kill enough immune cells; some survived to spread their malfunction once more.

Another interesting question is whether the malfunction occurs in the periphery, among mature immune cells, or in the hematopoietic stem cells that generate all immune cells. In either case different strategies might result. The present incarnation of Burt's approach involves hematopoietic stem cell transplant (HSCT) coupled with chemotherapeutic ablation of existing peripheral immune cells, so it covers all of the bases. It is a harsh therapy for patients, with a meaningful risk of death - it only makes sense for the worst cases, those facing death and grave disability without intervention. Given more selective, more gentle cell killing technologies, such as Oisin Biotechnologies' programmable suicide gene therapy, much better treatments might be built, and all autoimmunity controlled.

This is an important line of research and development, as a clean recreation of the immune system would also solve a great deal of the decline and dysfunction that arises with aging, clearing out misconfigured and damaged cells of many different varieties. It would solve all of the problems that the research community does not currently understand, as well as those identified and catalogued. Burt's work should be considered prologue to a future of immune recreation carried out using much more advanced technologies. It points the way.

For some multiple sclerosis patients, knocking out the immune system might work better than drugs

In multiple sclerosis (MS), a disease that strips away the sheaths that insulate nerve cells, the body's immune cells come to see the nervous system as an enemy. Some drugs try to slow the disease by keeping immune cells in check, or by keeping them away from the brain. But for decades, some researchers have been exploring an alternative: wiping out those immune cells and starting over. The approach, called hematopoietic stem cell transplantation (HSCT), has long been part of certain cancer treatments. A round of chemotherapy knocks out the immune system and an infusion of stem cells - either from a patient's own blood or, in some cases, that of a donor - rebuilds it. The procedure is already in use for MS and other autoimmune diseases at several clinical centers around the world, but it has serious risks and is far from routine. Now, new results from a randomized clinical trial suggest it can be more effective than some currently approved MS drugs.

Nearly 30 years ago, when hematologist Richard Burt saw how HSCT worked in patients with leukemia and lymphoma, he was struck by a curious effect: After those patients rebuilt their immune systems, their childhood vaccines no longer protected them. Without a new vaccination, the new immune cells wouldn't recognize viruses such as measles and mumps and launch a prompt counterattack. That suggested that in the case of an autoimmune disease, reseeding the immune system might help the body "forget" that its own cells were the enemy.

Burt and others have since used HSCT for a variety of autoimmune diseases, including rheumatoid arthritis and lupus. In the past few years, several teams have reported encouraging results in MS. But only one study - which evaluated just 17 patients - directly compared HSCT to other available drug treatments. In the new trial, Burt and his colleagues recruited 110 people with the most common form of MS, known as relapsing-remitting. In that form of the disease, patients can go long periods without symptoms - which include muscle weakness and vision problems - before inflammation flares up. Trial participants had at least two such relapses in the previous year, despite being on one of several approved MS drugs.

Half the participants continued with drug treatment but switched from a drug that wasn't working for them to a drug of a different class. The other half underwent HSCT. First, the researchers collected their blood to reinfuse later. Then, they gave patients a combination of drugs to kill most of their immune cells. In this trial, the patients would have regenerated their own immune systems with stem cells in bone marrow that were spared annihilation. But they received the reinfusion of their own stem cell-rich blood to help speed recovery by several days. A year later, the researchers evaluated how far the disease had progressed in each of the patients. According to a zero-to-10 scale of disability that includes measures of strength, coordination, and speech, roughly 25% of those in the drug treatment group showed at least a one-point worsening in their score, compared with just 2% of those in the transplant group. MRI scans also revealed less extensive brain lesions in the transplant group and improvements in a patient survey about quality of life. Five years after treatment, about 15% of people in the transplant group had had a relapse, versus about 85% of the control group.

Immune System Aging and the Neuroinflammation Hypothesis of Alzheimer's Disease

As is the case for other neurodegenerative conditions, Alzheimer's disease has a strong inflammatory component. Even if other mechanisms are important, and there is very strong evidence for this to be the case, dysregulation of immune cells in the brain contributes notably to the progression of the condition. As recent work demonstrates, this dysregulation may arise in large degree because of the inflammatory signaling generated by senescent cells, but these errant cells are are not the only way in which the aged, damaged immune system can become more inflamed and thus more hostile towards the tissues it is supposed to help maintain.

Inflammation for short periods of time is a necessary part of the immune response, and assists in the removal of pathogens and regeneration of structural damage. That same inflammation extended over the long-term, as occurs in aging, disrupts many vital processes in a wide range of cell populations and tissues. This is harmful in any tissue, but the resident immune cells of the central nervous system play important roles in all sorts of processes vital to the normal operation of the brain, such as the creation and maintenance of synaptic connections between neurons.

Pathologically, Alzheimer's disease (AD) brains harbor amyloid plaques that contain extracellularly deposited amyloid β (Aβ) from cleaved amyloid precursor protein, and neurofibrillary tangles formed by intracellular accumulation of hyperphosphorylated and misfolded tau protein. These characteristic entities inspired a leading theory that centers on the loss of proteostasis within the brain, which instigates the pathogenic course of AD. The Amyloid Cascade Hypothesis has guided numerous studies in the past two decades, which helped reveal insights of the neuronal properties and pathological events initiated by Aβ and subsequently by tau aggregation.

However, it is clear that late-onset Alzheimer's disease (LOAD) is collectively modified by numerous genetic factors that govern diverse cellular and molecular pathways, including many genes involved in the immune responses. Consequently, the Neuroinflammation Hypothesis emphasizes the dysregulation of central nervous system (CNS) immune response as a key factor in the etiology of neurodegenerative diseases. In recent years, neuroinflammation is increasingly recognized as an integral and critical contributor in AD pathogenesis.

The role played by the immune system in AD pathogenesis is prominent but is by no means limited to the brain. Copious evidence from clinical and experimental research suggests an influential, yet largely underappreciated, force in AD pathogenesis: systemic immune signals originating outside the brain. Despite genetic evidence implicating adaptive immunity in AD, it remains ill-defined how adaptive immune cells with limited presence inside the parenchyma exert their effects on AD pathologies and cognitive functions. Nevertheless, T cells have been shown to participate in other neurodegenerative diseases, such as Parkinson's disease and amyotrophic lateral sclerosis.

Many inconsistent results have been reported on the impacts of T cell subsets on CNS pathogenesis in Aβ-based experimental models. Noticeably missing at this time is the examination of tau-specific T cells and the possible involvement of Treg cells in tau pathology, a major gap in understanding the participation of the adaptive immune arm in AD pathogenesis. Despite the technical challenge to study rare cells, new technologies such as high-dimensional single-cell analysis should significantly improve the quantification and classification of diverse immune cell populations in the AD brain. Whether T cells and B cells, self-reactive or bystanders, afford protective immune surveillance or pathogenic immune attack requires thorough delineation.


Greater Modest Activity in Late Life Correlates with Lower Incidence of Dementia

Since the advent of low-cost, small accelerometers of the sort found in every modern mobile phone, it has been possible to gather much better data on the degree to which people are active or inactive. One of the findings that has emerged in epidemiological studies of exercise in older people is that even modest levels of activity appear to have a sizable correlation with health. This means puttering around in the kitchen or the garden, walking around the house little more, and the like. In the bigger picture, it is very reasonable to believe that exercise causes better health; this is proven in animal studies, even though the best that most human studies can do is to show an association. Exercise, like any treatment, has a dose-response curve of effects on health. Evidence in humans suggests that there is a big jump in benefits when moving from very low activity to merely low activity.

Older adults who move more than average, either in the form of daily exercise or just routine physical activity such as housework, may maintain more of their memory and thinking skills than people who are less active than average, even if they have brain lesions or biomarkers linked to dementia. "We measured levels of physical activity in study participants an average of two years prior to their deaths, and then examined their donated brain tissue after death, and found that a more active lifestyle may have a protective effect on the brain. People who moved more had better thinking and memory skills compared to those who were more sedentary and did not move much at all."

The study assessed 454 older adults; 191 had dementia and 263 did not. All participants were given physical exams and thinking and memory tests every year for 20 years. The participants agreed to donate their brains for research upon their deaths. The average age at death was 91 years. At an average of two years before death, researchers gave each participant an activity monitor called an accelerometer. The wrist-worn device monitored physical activity around the clock, including everything from small movements such as walking around the house to more vigorous activity like exercise routines. Researchers collected and evaluated seven days of movement data for each participant and calculated an average daily activity score. The results were measured in counts per day, with an overall average of 160,000 counts per day.

People without dementia had an average of 180,000 counts per day, and people with dementia had an average of 130,000 counts per day. Researchers found that higher levels of daily movement were linked to better thinking and memory skills. The study also found that people who had better motor skills - skills that help with movement and coordination - also had better thinking and memory skills. For every increase in physical activity by one standard deviation, participants were 31 percent less likely to develop dementia. For every increase in motor ability by one standard deviation, participants were 55 percent less likely to develop dementia.


More Funds are Assembled for Biotech Startups in the Field of Longevity Science

A number of entities are energetically raising funds to invest in biotech startups that aim to treat aging in some way. Beyond the more traditionally structured venture funds, such as the Longevity Fund, and technology funds like Kizoo Technology Ventures and Felicis Ventures that are turning their attention to biotech investment, there are also private equity / business development companies such as Juvenescence and Life Biosciences. Today I'll point out recent news for those two regarding their success in raising funding. This sort of thing is one of the signs of a building initial hype cycle for the first meaningful ways to intervene in aging, of which the most important is clearance of senescent cells via senolytic therapies of various types.

Highly promising new technologies always arrive with a great burst of investment, a period in which it is easy to raise funding for startup companies, a great deal of development takes place, and there is a much greater degree of enthusiasm for near term results than the reality merits. In addition to the useful projects that take place, emerging from those who know the ground well, there are also unsophisticated investors who will put funds into unwise projects. This always happens when there is a rush of this nature. Sooner or later those unwise projects come unraveled, the crash comes, and then there is some period in which everyone outside the industry is scornful, and investors who invested poorly shy away from the entire field, licking their wounds.

Once that is done and cooler heads prevail, a more tempered enthusiasm for progress will start to pick up again in a reasonable manner. The hype and the crash tends to obscure the fact that meaningful progress actually did occur as a result of at least some of the investment in the field, but humans being human we don't seem to have figured out a way to embark upon the creation of new industries without this initial excess and overreaction. It happened for railways, it happened for the internet, it will happen for rejuvenation.

So as a necessary step on the way towards the realization of the first of a future suite of rejuvenation therapies based on the SENS programs, those of use who have spent the past fifteen years or more trying to attract attention to this area of the life sciences should be pleased that matters have now reached the opening stages of the hype stage. Our efforts have successfully pushed the field forward. When the inevitable crash on the far side of the hype cycle arrives, we should welcome that also. Underneath the roller-coaster ride of investment that the press focuses on breathlessly, real and meaningful work will be taking place.

Anti-aging startup Juvenescence bags $46M for pipeline push

Juvenescence has raised the first $46 million tranche of series B financing en route to an anticipated $100 million round. The investment, which values Juvenescence at $400 million, tees the anti-aging startup to advance the multiasset pipeline it has built over the past 18 months toward readouts. Jim Mellon, a British billionaire biotech investor, created Juvenescence with early Medivation backer Greg Bailey and three others in 2017. Since then, the founders have used their cash and contacts to turbocharge the growth of Juvenescence with $115 million in investment. Juvenescence expects that figure to rise in the coming months when it closes the next tranche of a forecast $100 million round.

The rapid fundraising, and mooted 2019 IPO, reflect Juvenescence's belief that it is in the early stages of a longevity land grab. By pulling in handfuls of money, Juvenescence has been able to pen a string of deals and position itself to support the programs through to important readouts. Juvenescence already has its fingers in lots of pies. Using its early funding, the startup licensed assets from the Buck Institute for Research on Aging, bought controlling stakes in AgeX Therapeutics and LyGenesis - a pair of regenerative medicine players - formed artificial intelligence joint ventures with Insilico Medicine and Netramark and invested $10 million in a small molecule senolytics program.

Life Biosciences joins the longevity race

Life Biosciences will on Monday announce the completion of a $50M funding round - twice its original target - to invest in a range of approaches to extending healthy life. "We have undertaken a big land-grab of longevity-related intellectual property and we have pulled together a lot of the world's longevity scientists." Longevity is a rapidly expanding sector of the biotech industry, as scientists learn more about the way biological pathways fail in old age. Investors in Life Biosciences are mainly wealthy individuals and family trusts, reflecting a widespread view that ageing millionaires are keen to put some of their money into longevity research.

Life Biosciences had quietly raised $25M in an early financing round in 2017. It declined to disclose the company's current value but others familiar with the latest fundraising estimated the valuation at about $500M. "We are tackling all eight pathways of age-related decline." These include cellular senescence, stem cell exhaustion, and dysfunction in mitochondria (the energy-generating units in cells). Six "daughter companies" work semi-independently on different development projects. One such company, Senolytic Therapeutics, is developing compounds and technologies that target senescent cells. Researchers believe that destroying these "zombie" cells will counteract some of the adverse effects of ageing.

Calorie Restriction Slows Neural Stem Cell Decline, Perhaps via Reduced Cellular Senescence and Inflammation

The practice of calorie restriction is shown to slow all aspects of aging, though its effects on life span are much smaller in humans than in short-lived species. The health effects in our species are worth the effort, however, given that calorie restriction is both reliable in its production of benefits and free. Here, researchers note that calorie restriction slows the consequences of aging in neural stem cell populations, as is the case for stem cell populations elsewhere in the body as well. They suggest that this is the downstream consequence of reduced levels of cellular senescence and chronic inflammation.

Neural stem cells support the brain via neurogenesis, the creation of new neurons that can take their place in brain tissue and contribute to function. Neurogenesis diminishes with age, in line with the fact that stem cell populations throughout the body decline in activity with the progression of degenerative aging. One explanation for this phenomenon is that it is part of an evolved balance between cancer risk and the slow decline of tissue failure. Too much stem cell activity in a damaged system will raise the risk of cancer. The widespread use of stem cell therapies so far suggests that if this is the case, it isn't a finely-tuned balance; there is a lot of room to increase stem cell activity without provoking large increases in cancer risk.

The adult brain can generate new neurons from neural stem cells. The process of neurogenesis occurs throughout life primarily in the dentate gyrus of the hippocampus and the subventricular zone (SVZ). This process is highly regulated, and although the signals that control neurogenesis are not yet fully understood, it is known that neurogenesis declines with age, suggesting that the neurogenic signals are susceptible to age-related deficits observed elsewhere in the brain.

Calorie restriction is one mechanism by which age-related deficits may be reduced in aged animals. Calorie restriction can markedly increase mean and maximum lifespan and improve physiologic markers of health, including insulin sensitivity, body mass index, and plasma markers of cardiovascular disease. Calorie restriction has beneficial effects in blood and muscle stem cell function, and can protect against neuronal damage in neurodegenerative models. In the hippocampus, calorie restriction enhances proliferation of progenitor cells, although whether these newly born cells survive and mature into neurons is not clear.

Chronic inflammation is a known factor in aging, suggesting that inflammatory cells likely contribute to the development of deficits in the aging brain. Cellular senescence is a phenomenon by which cellular division ceases in the aged organism, and is modifiable in laboratory models. Inflammation is associated with senescence in in vitro models because senescent cells secrete pro-inflammatory cytokines.

In this study, we show that calorie restriction is protective against age-related increases in senescence and microglia activation and pro-inflammatory cytokine expression in an animal model of aging. Further, these protective effects mitigated age-related decline in neuroblast and neuronal production, and enhanced olfactory memory performance, a behavioral index of neurogenesis in the SVZ. Our results support the concept that calorie restriction might be an effective anti-aging intervention in the context of healthy brain aging.


Healthier Old Individuals Have a More Diverse Gut Microbiome

Researchers here comment on recent discoveries regarding age-related changes in the gut microbiome. In recent years, evidence has amassed for microbes in the gut to have a meaningful influence over the pace of aging, perhaps even in the same ballpark as that of regular moderate exercise. In the same way that healthier older people tend to be fitter, healthier older people also tend to have more diverse gut microbe populations. How much of this is cause versus the consequence of other factors, such as changes in diet or loss of immune function that occur in old age, remains a topic for debate. There is, however, more than enough evidence from animal studies to suggest that reverting gut microbes to a more youthful distribution is beneficial - though the size of the effect on lifespan is likely to be much smaller in our species, as is usually the case for interventions of this nature.

The human gut harbors trillions of bacteria (known as the gut microbiota), which play important roles in health and diseases. Several recent studies have characterized the human gut microbiome in the elderly. Gut microbial diversity generally decreases when people age, which is likely due to changes in physiology, diet, medication, and lifestyles. Decreased diversity, considered an indicator of an unhealthy microbiome, has been linked to different chronic conditions such as obesity and type 2 diabetes. In addition to decreased diversity, the changes of the gut microbiome composition to an imbalanced state, i.e. dysbiosis, also correlates with frailty, inflammation, and neurodegenerative disorders.

Given the fact that most of the elderly experience gut associated comorbidities, it is extremely challenging to define a healthy gut microbiome in this population. Changes in the gut environment such as inflammation, leaky gut, production of reactive oxygen species and application of medications can all affect the gut microbiome. In that regard, centenarians have been used as a model of healthy aging because of their capability to delay or avoid chronic diseases. Therefore, the gut microbiome in this cohort might be used to define a healthy gut microbiome. The genetics, and recently epigenetics, of the centenarians have been extensively investigated, but relatively little is known about their gut microbiotas until now.

Researchers examined the gut microbiome of a cohort of healthy, long-living Chinese individuals including nonagenarians (90-99 years old) and centenarians (older than 100). They found that this cohort of long-living people possesses a more diverse gut microbiota than younger adults, contradictory to conventional views. They also found that a group of bacteria, members of which are known short-chain fatty acid (SCFA) producers such as Clostridium cluster XIVa, are enriched in the long-living Chinese. To verify their discovery, they analyzed an independent Italian data set. Consistently, the long-living Italians also had more diverse gut microbiotas than the younger group. When they combined the Italian and the Chinese data sets, they found that although the gut microbiota structures are significantly different, probably due to the differences in diet, genetics, and environment, 11 of the top 50 bacterial features that differentiate the long-living individuals from the younger group were shared.

These studies clearly revealed that more diverse and balanced gut microbiotas are present in healthy, long-living people, whereas disturbed gut microbiotas with dysbiosis are observed in the elderly who suffer from different comorbidities. We thus hypothesize that modulation of the gut microbiome to maintain a healthy gut microbiome will promote healthy aging. One rationale behind this hypothesis is inflammaging, i.e. increased chronic, low-grade inflammation in the elderly, which is associated with different chronic diseases. SCFAs are important in maintaining gut homeostasis. SCFAs provide the primary energy for colon epithelial cells and possess anti-inflammation properties. The enrichment of these SCFA producers in long-living individuals suggests that these bacteria might reduce inflammation and its resulting damage in this cohort, which likely contributed to their healthy aging.


$771,393 Donated to the SENS Research Foundation at the End of 2018

The philanthropists of our community, of greater and lesser means, stepped up to provide more than three quarters of a million dollars to the SENS Research Foundation in the last months of 2018. The work of the SENS Research Foundation depends on our support: building the foundations for rejuvenation therapies that would not otherwise be constructed, unblocking important research that is stuck, cultivating vital but neglected fields of science. Look at the yearly reports for much more detail. This non-profit is entirely dependent on philanthropic donations to power the vital work undertaken by its staff and allies in the research community.

Thank you very much to everyone who contributed to 2018's Reimagine Aging end-of-year fundraising campaign. The original General Fund goal of $500,000 was our most ambitious yet, and you enabled us to exceed this goal for an incredible $771,393 total! We are grateful beyond measure for your generosity and support to continue our mission of curing age-related disease. Every dollar you give helps bring the future we all want to bring into existence.

A very special thanks to Vitalik Buterin for his incredible gift of $350,000 in Ethereum, as well to IAS, Josh Triplett, Reason, Christophe and Dominique Cornuejols, Didier Coeurnelle, and Olivier Roland for providing matching grants during this campaign.

Here at Fight Aging!, Josh Triplett, Christophe and Dominique Cornuejols, and I put up a challenge fund for SENS Patrons, the monthly donors that supply a steady stream of funding to the foundation. For several years now we've aimed to grow that community of grassroots donors. They are steady folk; 80% of all of those who sign up stick around for at least a year, and the more donations that arrive on a schedule, the easier it becomes for the SENS Research Foundation staff to plan ahead and organize longer-term projects. We didn't do as well in 2018 as in 2017, only hitting 50% of our goal: $29,987 out of the $54,000 target - but it wasn't very many years ago that this would have been a sizable set of funding for the small organization that the SENS Research Foundation was back then.

In general, 2018 was a more muted environment for charitable fundraising. It would have been hard to top the end of 2017, at the height of the cryptocurrency bubble, when a great deal of philanthropic funding was disbursed to many research organizations. Now we are back to the point of having to work hard once again to grow our community, to persuade people that, in the midst of enthusiasm over clearance of senescent cells as a rejuvenation therapy, there is a great deal more necessary work to accomplish. One success does not complete the job at hand - there are still forms of age-related damage for which the science continues to languish, and each of them is enough on its own to produce age-related disease and death.

The efforts of the SENS Research Foundation and allied groups such as the Methuselah Foundation are just as vital now that the first rejuvenation therapies have been achieved as they were when only the vision existed. The road is only partly traveled, the journey only just begun, and our help is still required.

One of the Ways Researchers Narrow the Search for Drugs to Slow Aging

Small molecule and drug candidate libraries are huge. Much of modern medical research is a process of screening subsets of those libraries in search of molecules that can produce benefits with minimal side-effects. Usually the output of a successful screen is taken as a starting point for further exploration and molecular tinkering, to improve the effect or minimize undesirable side-effects. The great hope for gene therapy is that it will render all of this largely obsolete by offering ways to directly influence a molecular mechanism to a configurable degree without meaningful side-effects. That remains a way off in the future, however, and meanwhile a very sizable slice of medical research is still all about finding which cataloged molecules might be interesting to work with.

Thus when it comes to aging, a majority of efforts are focused on adjusting the operation of metabolism via small molecules from the catalogs, interacting with one of the known aging-related mechanisms discovered via examination of the biology of calorie restriction, or autophagy, or other stress response mechanisms. This is somewhat depressing: none of this work offers either hope or possibility of doing more than slightly increasing human life span, yet it is where most the funding and effort is focused. An increasing fraction of those initiatives are concerned with ways to speed up this process, to make it more rational, to cut down the number of molecules to be assessed. These advances are interesting to the degree that they can be applied more generally, to any area of development. There are parts of the SENS rejuvenation research portfolio in which small molecule drug discovery might lead to useful therapies, for example.

Several bioinformatic methods have been developed to identify potential geroprotective drugs. For instance, caloric restriction (CR) mimetics have been identified, by comparing genes differentially expressed in rat cells exposed to serum from CR rats and rhesus monkeys with gene expression changes caused by drugs in cancer cell lines. Structural and sequence information on ageing-related proteins have been combined with experimental binding affinity and bioavailability data to rank chemicals by their likelihood of modulating ageing in the worm Caenorhabditis elegans and the fruit fly Drosophila melanogaster. Drug-protein interaction information has also been used to predict novel pro-longevity drugs for C. elegans, using a set of effective and ineffective lifespan-extending compounds and a list of ageing-related genes. A similar approach used chemical descriptors of ageing-related compounds from the DrugAge database together with gene ontology terms related to the drug targets. Enrichment of drug targets has been assessed for a set of human orthologs of genes modulating longevity in animal models to identify new anti-ageing candidates.

Despite the increasing interest in drug-repurposing for human ageing, research has tended to focus on predicting life-extending drugs for animal models. However, the translation from non-mammalian species to humans is still a challenge, and certain aspects of ageing may be human-specific. Only a few studies have focused on data from humans. For instance, researchers applied the GeroScope algorithm to identify drugs mimicking the signalome of young human subjects based on differential expression of genes in signalling pathways involved in the ageing process. Another study correlated a set of genes up- and down-regulated with age in the human brain with drug-mediated gene expression changes in cell lines from the Connectivity Map.

In the present study, we rank-ordered drugs according to their probability of affecting ageing, by measuring whether they targeted more genes related to human ageing than expected by chance, by calculating the statistical significance of the overlap between the targets of each drug and a list of human ageing-related genes. Additionally, to enhance the power of the approach, we mapped the drugs' gene targets and ageing-related genes to pathways, gene ontology terms, and protein-protein interactions, and repeated the analysis. We found that, independently of the data source used, the analysis resulted in a list of drugs significantly enriched for compounds previously shown to extend lifespan in laboratory animals. We integrated the results of seven ranked lists of drugs, calculated using the different data sources, into a single list, and we experimentally validated the top compound, tanespimycin, an HSP-90 inhibitor, as a novel pro-longevity drug.


What is Known of the Behavior of Regulatory T Cells in Aging Fat Tissue

Visceral fat tissue produces chronic inflammation through its interactions with the immune system. Numerous mechanisms are involved: generation of additional senescent cells and their inflammatory signaling; normal fat cells secreting signals similar to those of infected cells; DNA debris from dead fat cells; and others. In younger individuals, problematic inflammation arises through having too much fat tissue, being overweight or obese. In older individuals, however, many of the same problems of chronic inflammation arise even given lesser amounts of visceral fat tissue. This paper reviews some of the relevant mechanisms, comparing aging with obesity, looking for the differences under the hood in T cell behavior.

Basic aging mechanisms such as cellular senescence and diminished number or dysfunction of immune progenitor cells are causative factors of development of low-grade inflammation. Immunosenescence is a term to describe the decline of immune function associated with aging, which can lead to increased susceptibility to infections, cancer, and metabolic and autoimmune disorders. During the state of infection or tissue damage in healthy young individuals, the immune system moves quickly. After the effective removal of the invading pathogen, the host immune response must be deactivated and return to a quiescent state to prevent further tissue damage. A subset of T lymphocytes called regulatory T cells are responsible for suppressing the deleterious effects of immune response.

In general, both innate and adaptive immune systems are affected by aging, but adaptive immunity, especially T lymphocytes, are most susceptible to the detrimental effects of aging. Gradual deterioration of the immune system over the course of time leads to a mismatch between proinflammatory and anti-inflammatory signals that may disrupt inflammatory homeostasis causing inflammaging.

Inflammation in adipose tissue, mainly evidenced by increased accumulation and proinflammatory polarization of T cells and macrophages, has been well-documented in obesity and may contribute to the associated metabolic dysfunctions including insulin resistance. Studies show that increased inflammation, including inflammation in adipose tissue, also occurs in aging. Aging-associated inflammation in adipose tissue has some similarities but also differences compared to obesity-related inflammation. In particular, conventional T cells are elevated in adipose tissue in both obesity and aging and have been implicated in metabolic functions in obesity.

However, the changes and also possibly functions of regulatory T cells in adipose tissue are different in aging and obesity. In this review, we summarize recent advances in research on the changes of these immune cells in adipose tissue with aging and obesity and discuss their possible contributions to metabolism and the potential of these immune cells as novel therapeutic targets for prevention and treatment of metabolic diseases associated with aging or obesity.


Ceramides in Extracellular Vesicles Increase with Age and Induce Cellular Senescence

Much of the signaling that passes between cells travels via varieties of extracellular vesicle, tiny membrane-bound packages that contain a wide variety of presently poorly cataloged molecules. The varieties of vesicle are also poorly catalogued, and are at present given a loose taxonomy based on size. No doubt there are many subtypes within any given size category, depending on circumstance and mechanism, with the contents varying characteristically by subtype. Nothing is simple in cellular biology.

Vesicles are currently a subject of growing interest in many fields of medical research. In regenerative medicine, for example, it is hoped that harvesting vesicles from stem cells in culture and delivering them to patients can replicate much of the beneficial effects of stem cell therapies, but at a lower cost and with fewer complicating factors. Vesicles should not provoke immune reactions, for example, and thus do not require patient-matched or otherwise carefully chosen and engineered cells. In most cell therapies used to date, the transplanted cells die out quite rapidly. Beneficial outcomes result from the signals that they secrete, inducing changes in the native cell behavior. Thus why not just stop using the cells for this class of treatment?

Another area of interest is the way in which senescent cells manage to wreak havoc in tissues even when they are present in small numbers. They generate a potent mix of signals that creates chronic inflammation, destructively remodels the surrounding extracellular matrix, and alters the behavior of other cells for the worse, directly or indirectly. Moreover, senescent cells encourage other cells to become senescent. Therefore we should expect to see intracellular signals in the aged environment that can induce senescence. Those are starting to be discovered: versican is one example, to go along with the very long chain ceramides noted in today's paper.

The vesicles containing these molecules may be secreted by senescent cells. Or they may be generated in other ways, implying that the state of senescence is more readily achieved in older, damaged tissues independently of existing senescent cells. Or both. Knowing more about these mechanisms will inform the appropriate use of senolytic drugs to remove senescent cells in the years to come: if senescence occurs more often in old tissues, then senolytic drugs should be used more often rather than less often by older people. If, on the other hand, new senescence is largely driven by existing senescence, then much more infrequent use is all that is needed.

Very Long-Chain C24:1 Ceramide Is Increased in Serum Extracellular Vesicles with Aging and Can Induce Senescence in Bone-Derived Mesenchymal Stem Cells

Emerging patterns of disease progression suggest that degenerative changes in one organ or system are likely to contribute to degenerative changes in other organs and systems. For example, reductions in lean mass and bone loss have both been observed to precede the age-related development of cognitive impairment and Alzheimer's disease. Thus, cross-talk among various cells, tissues and organs may underlie non-autonomous aging in different cell and tissue populations. This concept is supported by studies in which young cells exposed to aged serum exhibited changes characteristic of older cells.

A barrier to progress in correcting the problem of age-related tissue dysfunction is the poor understanding of the molecular and cellular mechanisms underlying these non-autonomous cellular communication pathways. Exosomes are small (40-150 nm) and microvesicles are larger (more than 100 nm) membrane-derived structures that are released into the extracellular space by a variety of cell types. These membrane-bound extracellular vesicles (EVs) can transport proteins, lipids, and mRNAs between cells, delivering these molecules to target cells. EVs are highly enriched in the sphingolipid ceramide, which is known to promote cell senescence and apoptosis. In addition, EVs play a key role in a number of pathologies in vivo such as cancer metastasis and neurodegenerative disease. Thus, EV-derived ceramide is one potential aging factor that may promote degeneration in multiple organs and tissues.

We investigated the ceramide profile of serum exosomes from young (24-40 years) and older (75-90 years) women and young (6-10 years) and older (25-30 years) rhesus macaques to define the role of circulating ceramides in the aging process. EVs were isolated using size-exclusion chromatography and specific ceramide species were identified with lipidomic analysis. Results show a significant increase in the average amount of C24:1 ceramide in EVs from older women (15.4 pmol/sample) compared to those from younger women (3.8 pmol/sample). Results were similar in non-human primate serum samples with increased amounts of C24:1 ceramide (9.3 pmol/sample) in older monkeys compared to the younger monkeys (1.8 pmol/sample).

In vitro studies showed that primary bone-derived mesenchymal stem cells (BMSCs) readily endocytose serum EVs, and serum EVs loaded with C24:1 ceramide can induce BMSC senescence. Elevated ceramide levels have been associated with poor cardiovascular health and memory impairment in older adults. Our data suggest that circulating EVs carrying C24:1 ceramide may contribute directly to cell non-autonomous aging.

Large Genome-Wide Study Finds Only a Few Genetic Influences on Human Longevity

The influence of genetic variants on natural variations in human longevity is a very complex matter. The evidence to date supports a model in which thousands of genes have individually tiny, conditional effects. Near all associations identified in any given study population have failed to appear in any of the other study populations, and effect sizes for the very few longevity-associated genes that do appear in multiple studies are not large in the grand scheme of things. These variants provide a small increase in the odds of living to be very old, but the individuals bearing them are still diminished and damaged by aging. The genetics that determine how cellular metabolism gives rise to variations in aging are of great scientific interest, but there is nothing here that can act as the foundation for therapies that will help people to live significantly longer.

The extent of the role of genetic variation in human lifespan has been widely debated, with estimates of broad sense heritability ranging from around 25% based on twin studies to around 16.1% based on large-scale population data. One very recent study suggests it is much lower still (less than 7%), pointing to assortative mating as the source of resemblance amongst kin. Despite this modest heritability, extensive research has gone into genome-wide association studies (GWAS) finding genetic variants influencing human survival. Only two robustly replicated, genome-wide significant associations (near APOE and FOXO3) have been made to date, however.

An alternative approach is to study lifespan as a quantitative trait in the general population and use survival models to allow long-lived survivors to inform analysis. However, given the incidence of mortality in middle-aged subjects is low, studies have shifted to the use of parental lifespans with subject genotypes, circumventing the long wait associated with studying age at death in a prospective study. In addition, the recent increase in genotyped population cohorts around the world, and in particular the creation of UK Biobank, has raised GWAS sample sizes to hundreds of thousands of individuals, providing the statistical power necessary to detect genetic effects on mortality. A third approach is to gather previously published GWAS on risk factors thought to possibly affect lifespan, such as smoking behaviour and cardiovascular disease (CVD), and estimate their actual independent, causal effects on mortality.

Here, we blend these three approaches to studying lifespan and perform the largest GWAS on human lifespan to date. First, we leverage data from UK Biobank and 26 independent European-heritage population cohorts to carry out a GWAS of parental survival. We then supplement this with data from 58 GWAS on mortality risk factors. Finally, we use publicly available case-control longevity GWAS statistics to compare the genetics of lifespan and longevity and provide collective replication of our lifespan GWAS results.

We identified 11 novel genome-wide significant associations with lifespan and replicated six previously discovered loci. We also replicated long-standing longevity SNPs near APOE, FOXO3, and 5q33.3/EBF1 - albeit with smaller effect sizes in the latter two cases - but found evidence of no association (at effect sizes originally published) with lifespan for more recently published longevity SNPs near IL6, ANKRD20A9P, USP42, and TMTC2. Despite studying over 1 million lives, our standard GWAS only identified 12 variants influencing lifespan at genome-wide significance. This contrasts with height (another highly polygenic trait) where a study of around 250,000 individuals found 423 loci.

This difference can partly be explained by the much lower heritability of lifespan (0.12 versus 0.8 for height), consistent with evolution having a stronger influence on the total heritability of traits more closely related to fitness and limiting effect sizes. In addition, the use of indirect genotypes reduces the effective sample size to 1/4 for the parent-offspring design. When considering these limitations, we calculate our study was equal in power to a height study of only around 23,224 individuals, were lifespan to have a similar genetic architecture to height. Under this assumption, we would require a sample size of around 10 million parents (or equivalently 445,000 nonagenarian cases, with even more controls) to detect a similar number of loci.

Individual genetic variants that increase dementia, cardiovascular disease, and lung cancer - but not other cancers - explain the most variance in lifespan. We hoped to narrow down the search and discover specific genes that directly influence how quickly people age, beyond diseases. If such genes exist, their effects were too small to be detected in this study. The next step will be to expand the study to include more participants, which will hopefully pinpoint further genomic regions and help disentangle the biology of ageing and disease.


Blood-Brain Barrier Dysfunction as an Early Driver of Dementia

The blood-brain barrier surrounds blood vessels in the brain, enforcing restrictions on the passage of molecules and cells between brain and blood supply. Like all bodily systems, the blood-brain barrier breaks down with aging, yet another consequence of rising levels of cellular damage and disarray. The passage of inappropriate cells and molecules into the brain is thought to cause a range of issues, but, as is the case for all aspects of the biochemistry of the brain, this is a very complex environment and set of processes. Firm answers are ever elusive, and a great deal of the fine detail of the aging of the brain has yet to be robustly cataloged. The relative importance of different forms of damage and dysfunction are not well established in many cases. It is challenging to make that sort of determination given the many interacting forms of degeneration that combine to cause dementia in old age, but results such as those presented here are nonetheless intriguing.

Leaky capillaries in the brain portend early onset of Alzheimer's disease as they signal cognitive impairment before hallmark toxic proteins appear. This finding could help with earlier diagnosis and suggest new targets for drugs that could slow or prevent the onset of the disease. A five-year study, which involved 161 older adults, showed that people with the worst memory problems also had the most leakage in their brain's blood vessels - regardless of whether abnormal proteins amyloid and tau were present. In healthy brains, the cells that make up blood vessels fit together so tightly they form a barrier that keeps stray cells, pathogens, metals, and other unhealthy substances from reaching brain tissue. Scientists call this the blood-brain barrier. In some aging brains, the seams between cells loosen, and the blood vessels become permeable.

Participants in the study had their memory and thinking ability assessed through a series of tasks and tests, resulting in measures of cognitive function and a clinical dementia rating score. Individuals diagnosed with disorders that might account for cognitive impairment were excluded. The researchers used neuroimaging and cerebral spinal fluid analysis to measure the permeability, or leakiness, of capillaries serving the brain's hippocampus, and found a strong correlation between impairment and leakage. "The results were really kind of eye-opening. It didn't matter whether people had amyloid or tau pathology; they still had cognitive impairment."


Accelerated Bone Regeneration via Transplant of Engineered Perivascular Stem Cells

Reprogramming stem or progenitor cells to adjust their behavior is growing in popularity as an approach to regenerative medicine. The large reductions in the cost of exploring cellular mechanisms achieved over the past twenty years mean that there is now a much greater understanding of relevant mechanisms, as well as a greater capacity to discover novel targets of interest for specific goals in altered cell behavior. The more straightforward outcome in this part of the field is simply to increase stem cell activity, to reduce the amount of time these cells spend quiescent rather than actively supplying tissue with new daughter somatic cells to assist in repair. As today's open access paper illustrates, there are certainly other options on the table, however.

Many stem cell populations are multipotent, meaning that they are capable of generating several different types of somatic cell. If only one type is desired for regeneration, then steering the stem cells into creating only that type for a while is effectively the same thing as speeding up their activity in general. Researchers here do this for cells that create both fat and bone tissue, identifying a regulatory protein, WISP1, that determines which is produced. These cells can then be harvested, engineered to express a higher level of WISP1, and used as a cell therapy to accelerate bone regrowth. That, at least, is the hope, given the initial evidence here from an animal study.

Stem Cell Signal Drives New Bone Building

Stem cells have the potential to develop into a variety of cell types including those that make up living tissues, such as bones. Scientists have long sought ways to manipulate the growth and developmental path of these cells, to repair or replace tissue lost to disease or injury. Previous studies showed that a particular type of stem cell - perivascular stem cells - had the ability to become either bone or fat, and that the protein WISP-1 plays a key role in directing these stem cells.

In a new study, researchers engineered stem cells collected from patients to block the production of the WISP-1 protein. Looking at gene activity in the cells without WISP-1, they found that four genes that cause fat formation were turned on 50-200 percent higher than control cells that contained normal levels of the WISP-1 protein. The team then engineered human fat tissue stem cells to make more WISP-1 protein than normal, and found that three genes controlling bone formation became twice as active as in the control cells, and fat driving genes such as peroxisome proliferator-activated receptor gamma (PPARγ) decreased in activity in favor of "bone genes" by 42 percent.

The researchers next designed an experiment to test whether the WISP-1 protein could be used to improve bone healing in rats that underwent a type of spinal fusion. The researchers mimicked the human surgical procedure in rats, but in addition, they injected - between the fused spinal bones - human stem cells with WISP-1 turned on. After four weeks, the researchers studied the rats' spinal tissue and observed continued high levels of the WISP-1 protein. They also observed new bone forming, successfully fusing the vertebrae together, whereas the rats not treated with stem cells making WISP-1 did not show any successful bone fusion during the time the researchers were observing.

WISP-1 drives bone formation at the expense of fat formation in human perivascular stem cells

The vascular wall within adipose tissue is a source of mesenchymal progenitors, referred to as perivascular stem/stromal cells (PSC). Those factors that promote the differentiation of PSC into bone or fat cell types are not well understood. Here, we observed high expression of WISP-1 among human PSC in vivo, after purification, and upon transplantation in a bone defect. Next, modulation of WISP-1 expression was performed, using WISP-1 overexpression, WISP-1 protein, or WISP-1 siRNA. Results demonstrated that WISP-1 is expressed in the perivascular niche, and high expression is maintained after purification of PSC, and upon transplantation in a bone microenvironment.

In vitro studies demonstrate that WISP-1 has pro-osteogenic/anti-adipocytic effects in human PSC, and that regulation of BMP signaling activity may underlie these effects. In summary, our results demonstrate the importance of the matricellular protein WISP-1 in regulation of the differentiation of human stem cell types within the perivascular niche. WISP-1 signaling upregulation may be of future benefit in cell therapy mediated bone tissue engineering, for the healing of bone defects or other orthopedic applications.

Suppression of Neural Plasticity in the Visual Cortex Reversed in Adult Mice

Researchers here identify a mechanism that suppresses neural plasticity in the visual cortex of adult mice, a part of the developmental process that permits greater plasticity in childhood, but then restricts it in adults. This plasticity is the generation and integration of new neurons into neural circuits. Increased plasticity in adults may be beneficial, allowing for better maintenance and regeneration in the aging brain. That benefit must be balanced against whatever functional reason has led evolution to establish diminished plasticity with advancing age. If resistance to cancer is the answer, similar to the explanation for reduced stem cell function throughout the body in later life, then this can be addressed along the way. If there are other functional reasons for lower levels of plasticity in adults, and thus increased plasticity might damage the adult brain in some way, such as by causing disarray in established neural networks, then this will be more challenging to resolve.

The human brain is very plastic during childhood, and all young mammals have a critical period when different areas of their brains can remodel neural connections in response to external stimuli. Disruption of this precise developmental sequence results in serious damage; conditions such as autism potentially involve disrupted critical periods. "It's been known for a while that maturation of inhibitory nerve cells in the brain controls the onset of critical period plasticity, but how this plasticity wanes as the brain matures is not understood. We've had some evidence that a set of molecules called SynCAMs may be involved in this process, so we decided to dig deeper into those specific molecules."

The study focused on the visual cortex, the part of the brain responsible for processing visual scenes, in which plasticity has been examined in many species. The researchers were able to measure activity of neurons in awake mice freely responding to visual stimuli. They found that removal of the SynCAM 1 molecule from the brain increased plasticity in the visual cortex of both young and adult mice. Further research found that SynCAM 1 controls a very specific type of neuronal connection termed synapses: the long-distance synapses between the visual thalamus, located beneath the cerebral cortex, and inhibitory neurons in the cortex. SynCAM 1 was found to be necessary for the formation of synapses between thalamus and inhibitory neurons, which in turn helps inhibitory neurons to mature and actively restrict critical period plasticity.

The researchers liken inhibitory neurons to a dial controlling when brain plasticity can occur. Plasticity is needed during early development, as the function of different brain areas matures. Mature function is then cemented into place by molecules like SynCAM 1. "Therefore, the limited ability of the mature brain to change is not simply a consequence of age but is directly enforced by the SynCAM 1 mechanism. This allows us to target the mechanism to re-open plasticity in the mature brain, which could be relevant for treating disorders like autism. Combined with the latest approaches in genetic manipulation, this may prove to be a new path to tackle both childhood disorders and brain injury in adults."


MANF Declines with Age and is Required for Parabiosis Benefits to the Liver

Researchers have identified MANF as a factor responsible for at least some of the benefits provided to the older of two animals with linked circulatory systems. Joining two animals, usually mice, in this way is known as parabiosis. It has been used a tool to explore the role of the signaling environment of blood and tissues in aging. Stem cell function, for example, declines with age, and a sizable part of that decline appears to be a reaction to the changing, damaged environment rather than inherent damage in the stem cells themselves. Thus signals must exist to mediate the altered behavior of cells in response to what is going on around them.

If signals exist, then they can be overridden. Some research groups are searching for factors in young blood that might be used to boost stem cell function and tissue function in old mice. Other groups are convinced that the effect is due to dilution of harmful factors in old blood rather than the addition of helpful factors in young blood. The evidence on both sides is compelling, and the conflicts are yet to be resolved. While that debate is ongoing, it seems reasonable to expect further discoveries of signals and regulators that can increase stem cell activity in old tissues to some degree. That tends to help spur greater tissue maintenance and repair, but with some presently unknown additional cancer risk as damaged cells are forced back to work.

Older mice who are surgically joined with young mice in order to share a common bloodstream get stronger and healthier, making parabiosis one of the hottest topics in age research. Researchers report that MANF (mesencephalic astrocyte-derived neurotrophic factor) is one of the factors responsible for rejuvenating the transfused older mice. Researchers also show the naturally-occurring, evolutionarily-conserved repair mechanism protects against liver damage in aging mice and extends lifespan in flies.

While researchers have yet to understand why MANF levels decrease with age, MANF deficiency has obvious hallmarks. Flies genetically engineered to express less MANF suffered from increased inflammation and shorter lifespans. MANF-deficient mice had increased inflammation in many tissues as well as progressive liver damage and fatty liver disease. Older mice who shared blood with MANF-deficient younger mice did not benefit from the transfusion of young blood.

"MANF appears to regulate inflammatory pathways that are common to many age-related diseases. We are hoping its effects extend beyond the liver, we plan to explore this in other tissues. The search for systemic treatments that would broadly delay or prevent age-related diseases remains the holy grail of research in aging. Given that MANF appears to modulate the immune system, we are excited to explore the larger implications of its therapeutic use. We are also cautious. There are many tissues and organ systems to evaluate in terms of MANF and we have yet to determine its effects on lifespan in the mouse."


Nattokinase and Reversal of Atherosclerotic Lesions

Atherosclerosis is one of the great killers. Fatty deposits form in blood vessels walls, narrowing and weakening the vessels. Eventually something ruptures, and the result is a stroke or heart attack, but even absent that the condition can narrow vessels sufficiently to cause fatal coronary artery disease. Even with modern medicine, the condition is inexorable: the toolkit doesn't yet include a way to more than slightly reverse the buildup of these plaques, and medical professionals must focus on ways to incrementally slow the progression of atherosclerosis rather than delivering any true cure.

One of the side-effects of starting a company, Repair Biotechnologies, that is working on a way to reverse atherosclerotic plaque is that I've been doing a great deal more reading on the topic of atherosclerosis than I would otherwise have done in the course of writing Fight Aging! Thus I turn up interesting items from the past few years that I missed at the time because I lacked the context to understand why they were worthy of notice, or just didn't have the sort of focus on atherosclerosis that I have at the moment. The papers I'll share today fall into this category, providing evidence for nattokinase, a very simple and readily available supplement, to have a surprisingly large effect on atherosclerotic lesions in humans. After six months of treatment, a third of the lesions were removed.

A clinical study on the effect of nattokinase on carotid artery atherosclerosis and hyperlipidaemia

All enrolled patients were from the Out-Patient Clinic of the Department of TCM at the 3rd Affiliated Hospital of Sun Yat-sen University. Using randomised picking method, all patients were randomly assigned to one of two groups, nattokinase (NK) and statin (ST) group. NK Group-patients were given NK at a daily dose of 6000 FU and ST Group-patients were treated with statin (simvastatin 20 mg) daily. The treatment course was 26 weeks. Common carotid artery intima media thickness (CCA-IMT), carotid plaque size and blood lipid profile of the patients were measured before and after treatment.

A total of 82 patients were enrolled in the study and 76 patients completed the study. Following the treatments for 26 weeks, there was a significant reduction in CCA-IMT and carotid plaque size in both groups compared with the baseline before treatment. The carotid plaque size and CCA-IMT reduced from 0.25±0.12cm2 to 0.16±0.10cm2 and from 1.13±0.12mm to 1.01±0.11mm, repectively. The reduction in the NK group was significantly profound, a 36.6% reduction in plaque size in NK group versus 11.5% change in ST group. Both treatments reduced total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG).

Nattokinase: A Promising Alternative in Prevention and Treatment of Cardiovascular Diseases

Nattokinase (NK), the most active ingredient of natto, possesses a variety of favourable cardiovascular effects and the consumption of Natto has been linked to a reduction in cardiovascular disease mortality. Recent research has demonstrated that NK has potent fibrinolytic activity, antihypertensive, anti-atherosclerotic, and lipid-lowering, antiplatelet, and neuroprotective effects. This review covers the major pharmacologic effects of NK with a focus on its clinical relevance to cardiovascular disease.

This effect size on atherosclerotic lesions is big enough to be suspicious, given that nattokinase is a supplement in common use, and the dose used is not outrageously large. We seem to be seeing a lot of that sort of thing these days, however; sometimes significance goes unnoticed, but equally sometimes it is an issue with the study that will be corrected later. It is hard to tell which without meaningful further effort. Does bisphosphonate treatment actually extend life expectancy by five years, and did this really did go unnoticed despite its widespread use in older people? Is fisetin actually a significantly effective senolytic compound in humans despite being widely used; did the very high senolytic dose in comparison to the usual supplement dose successful hide this property? How did nearly twenty years of earnest development and use of the chemotherapeutic dasatinib go past without anyone noticing that it killed enough senescent cells to improve health and measures of aging in mice and people? And so forth.

Over the past few decades, hundreds of millions of dollars (at the very least) have been spent on clinical trials to try to reverse atherosclerosis - to give existing repair systems in the body sufficient breathing space or increased capacity, allowing them to break down the fatty deposits that form in blood vessels. The sponsors of any of those trials would have been ecstatic to find a reliable reversal of atherosclerotic plaque that was half the size of that noted in the nattokinase trial here. One might take a look at a 2012 review paper that surveys the degree to which treatments at the time could achieve the goal of reversing atherosclerosis. A reversal of 15-20% in an unreliable fraction of patients was about the best that could be done. Most approaches were considerably less effective than that. Not a lot has changed in this high level picture since then.

At present the dominant approach to treatment of atherosclerosis is reduction of blood cholesterol, the cholesterol attached to LDL particles, or LDL-C. Statins are the long-standing approach, and are now being joined by even more effective treatments such as PCSK9 inhibitors. This slows down atherosclerosis by (a) lowering overall cholesterol, and thus freeing up some fraction of the macrophage cells that would otherwise have had to shovel it out of blood vessel walls, but more importantly (b) lowering oxidized cholesterol, which is very damaging to macrophages. When considering atherosclerosis and its treatments it is important to consider macrophages: they are drawn to the fatty lesions, and their task once there is to mine cholesterol from the lesion, ingest it, and hand it off to HDL particles that carry it back to the liver for excretion. This is called reverse cholesterol transport.

Atherosclerosis exists because macrophages become overwhelmed, mostly by oxidized cholesterol, but also by sheer volume of cholesterol, or by an overly inflammatory environment. They become agitated, call for help, become foam cells (some of which become senescent, causing further issues) or die. Most of a plaque is made up of the debris of dead macrophages, and the plaque itself is a self-expanding disaster area that calls ever more macrophages to their doom. Reducing the LDL-C slows down this feedback loop, but it cannot do much for existing plaques. There is some regression (the aforementioned 15-20% at best) because macrophages are given some breathing room, but plaques continue to grow at the new slower pace, and people continue to die.

There has been a considerable amount of work undertaken over the years on alternatives to lowering LDL-C. Researchers have tried all sorts of ways to improve the ability of macrophages to mine cholesterol and send it back to the liver. They have tried increased numbers of HDL particles (which are formed from APOA1 protein). They have tried altered forms of APOA1 found in some human populations that are associated with lower levels of atherosclerosis. They have tried the introduction of artificial HDL particles to swell the numbers. They have tried upregulation of the ABCA1 and ABCG1 proteins that perform the actual handoff of cholesterol molecules to APOA1. There is more in the same vein.

All of these things work pretty well in mice; the current best approaches produce 50% reversion of atherosclerotic lesions in animal studies. Yet all of those tried in humans, meaning the HDL and APOA1 approaches, have failed miserably in clinical trials. What this means is that there is something that the research community doesn't yet understand in the low-level detailed differences between human and mouse reverse cholesterol transport. That is a big roadblock for anyone turning up to propose some form of enhanced cholesterol transport as a therapy, even if intending to try one of the varied effective-in-mice approaches that hasn't yet been trialed in humans.

In this context, one can see that evidence for a common supplement to manage 36% reversion of lesions in humans is both welcome and jarring. It will certainly have to be replicated before many researchers in the LDL-C-focused side of the scientific community are likely to take it all that seriously. Any simple, easily obtained improvement should be welcome. Nonetheless, it is still only reversion by a third. The disease will still progress, and will still kill people. The research community has to do better than this.

The Second Ending Age-Related Diseases Conference will be Held in July 2019

The second Ending Age-Related Diseases conference, hosted by the Life Extension Advocacy Foundation (LEAF) staff and volunteers, will be held in New York this coming July. It will bring together entrepreneurs, investors, and researchers to discuss progress towards bringing aging under medical control, and thus creating true cures for age-related conditions. I attended last year's inaugural conference in the series, and recommend it. LEAF puts on a good conference, so consider registering.

After the incredible success of the conference Ending Age-Related Diseases 2018, the Life Extension Advocacy Foundation is happy to announce its second annual conference, Ending Age-Related Diseases 2019, which is to be held at Cooper Union in New York City on July 11-12th, 2019. The conference is aimed at focusing the NYC business community's attention on the current state of aging and rejuvenation research that has the potential to prevent and cure age-related diseases. With multiple research projects targeting the underlying processes of aging in order to develop preventive medicines, promoting collaboration between academia, the rejuvenation industry, and investors becomes an increasingly important task.

The list of confirmed speakers already includes renowned researchers and visionaries, such as Dr. Aubrey de Grey (SENS Research Foundation), Michael Greve (KIZOO Technology Ventures, Forever Healthy Foundation), Dr. Vadim Gladyshev (Harvard Medical School), Dr. Vera Gorbunova (University of Rochester), Dr. Alex Zhavoronkov (Insilico Medicine), and Reason and Bill Cherman (Repair Biotechnologies), with more speakers from rejuvenation biotechnology companies and the investment sector to be confirmed soon.

"This year's conference will focus on two main topics. The first topic will be progress in aging research, from fundamental studies to the interventions that are being tested in human clinical trials and the development of reliable biomarkers of aging. The second topic will be devoted to the hurdles of implementing these emerging rejuvenation biotechnologies into clinical practice, with a special focus on investment, the regulatory landscape, and the preparedness of the medical community. This way, we hope not only to attract the attention of investors to these very promising medical innovations but also to promote public dialogue on how to ensure their availability and accessibility to our aging society."


Versican May Increase Cellular Senescence and Calcification in the Blood Vessels of Hyperglycemic Patients

I found this paper quite intriguing, as it links together a number of themes in vascular aging and the similar forms of vascular dysfunction seen in metabolic syndrome and diabetes. The molecular damage of aging in blood vessel walls causes stiffness of blood vessels, which in turn causes hypertension. This is one of the more important means by which low level biochemical damage is translated to high level structural damage to tissues, as raised blood pressure causes all sorts of harm. The damage that leads to vascular stiffness includes (a) cross-linking, in which sugary metabolic byproducts form links between molecules of the extracellular matrix, impeding its elasticity, (b) calcification, in which cells begin to inappropriately deposit calcium into the extracellular matrix, also degrading elasticity, and (c) failure of the vascular smooth muscle cells to perform appropriately when constricting or dilating blood vessels.

This last item has a number of poorly mapped underlying causes, but chronic inflammation appears to be a contributing issue. Chronic inflammation is also implicated in calcification. Chronic inflammation is one of the downstream consequences of cellular senescence, and there is evidence for the presence of senescent cells to be involved in calcification in blood vessel walls. So these items are already quite well connected together. The paper here closes the loop further by finding a form of intracellular signaling that is likely present in hyperglycemic individuals, who also exhibit raised levels of cross-linking, that spurs the formation of more senescent cells in blood vessel walls. Hyperglycemia is just the excessive case: everyone who consumes the usual modern amount of dietary sugar is probably in an incrementally worse position over the long term than people who consume less sugar, due to this and related mechanisms.

A major determinant of vascular aging is vascular calcification, characterized by vascular smooth muscle cells (VSMCs) calcification. Transdifferentiation of VSMCs into osteoblasts is considered to be the most critical pathophysiological of VSMCs calcification. There is accumulating evidence suggesting that VSMCs calcification/senescence have central roles in the development and progression of diabetes-related cardiovascular disorders.

The vascular response to hyperglycemia is a multifactorial process involving endothelial cells (ECs) and VSMCs, although the mechanism by which the information in circulating blood are transferred from ECs to VSMCs is yet to be understood. Signaling between ECs and VSMCs is crucial for the pathogenesis of diabetic vascular calcification/aging. However, how does circulating high glucose affect the calcification/senescence of VSMCs that are not directly contact with the blood? Exosomes, small vesicles with a diameter of 40-100 nm released from various cell types, have gained much attention for their role in intercellular communication. Exosomes can transfer active proteins, lipids, small molecules, and RNAs from their cell of origin to the target cell. ECs have been demonstrated to secrete exosomes, and the transfer of signaling molecules by exosomes may thus provide a way for communicating between ECs and VSMCs. Similarly, prior study has demonstrated that exosomes from senescent ECs promotes VSMCs calcification.

Exosomes from human umbilical vein endothelial cells (HUVEC-Exos) were isolated from normal glucose (NG) and high glucose (HG) stimulated HUVECs (NG/HG-HUVEC-Exos). Exosomes isolated from HG-HUVEC-Exos induced calcification/senescence in VSMCs. HG-HUVEC-Exos significantly increased lactate dehydrogenase (LDH) activity, as well as the product of lipid peroxidation, and decreased oxidative stress marker activity, as compared with NG-HUVEC-Exos. Moreover, mechanism studies showed that mitochondrial membrane potential and the expression levels of mitochondrial function related protein HADHA and Cox-4 were significantly decreased in HG-HUVEC-Exos compared to controls. Proteomic analysis showed that HG-HUVEC-Exos consisted of higher level of versican (VCAN), as compared with NG-HUVEC-Exos.

VCAN is mainly localized to the mitochondria of VSMCs. Knockdown of VCAN with siRNA in HUVECs, inhibited HG-HUVEC-Exos-induced mitochondrial dysfunction and calcification/senescence of VSMCs. Our data suggest a functional role for VCAN inside VSMCs. VCAN carried by HG-HUVEC-Exos promotes VSMCs calcification/senescence, probably by inducing mitochondrial dysfunction. Since VSMCs calcification/senescence could induce vascular dysfunction, blockage of the exosome-mediated transfer of VCAN between these two cells may serve as a potential therapeutic target against diabetic vascular complications. More work will be needed to explore this possibility and to better understand the intracellular roles of VCAN.


Impressions from the January 2019 Juvenescence Gathering

The JP Morgan Healthcare conference took place in San Francisco this past week. The conference is less interesting in and of itself, but it is the spur for any number of other short gatherings of various biotech investment and business interest groups. So in the middle of last week, Jim Mellon and the other Juvenescence principals were in town to host their second annual showcase for startups working on aging, and the BioAge and Felicis Ventures folk hosted the overlapping Extending Human Lifespan event on the same day. I had to miss that second one, as I was presenting Repair Biotechnologies at the Juvenescence event to a small crowd of other entrepreneurs, angel investors, and venture capitalists of varied allegiances, and stayed for the whole event to see the other presentations.

Many of our fellow travelers associated with SENS rejuvenation research and Methuselah Foundation spheres were present to meet and greet: the SENS Research Foundation folk; much of the Oisin Biotechnologies team; Doug Ethell of Leucadia Therapeutics; Frank Schüler of Forever Healthy Foundation; a number of angel investors I've interacted with in the past while we were interested in the same companies; and many others arriving and leaving as they moved between events.

One thing that caught my eye is that the theme of diversity and new hypotheses in Alzheimer's research (or outright rebellion against the past two decades of relentless focus on clearing amyloid via immunotherapies, present it as you will) has robustly made its way to the commercial development stage. Leucadia Therapeutics were presenting their latest work on ferrets as an animal model to illustrate that the development of Alzheimer's occurs due to blocked drainage of cerebrospinal fluid though the cribriform plate. Related company Enclear Therapies was not present, but was a topic of discussion given that their founders have very similar thoughts on filtration of cerebrospinal fluid. Maxwell Biosciences principals presented their work on the LL-37 antimicrobial peptide as a test of the microbial theories of Alzheimer's disease, in which infection is provoking greater aggregation of amyloid and inflammation to accelerate other aspects of the condition. An attempt at intervention is perhaps the best way to clear up questions of causality here: do we see microbial infections in the Alzheimer's brain because they are an important cause, or because immune dysfunction in general tends to be more advanced in these patients?

A further contingent of startups at the Juvenescence event were similarly of interest for having a good shot at answering scientific questions very much faster than the academic community can, due to the influx of resources from the venture community. Elevian falls into this category, with their work on GDF11. Early work on parabiosis, joining the circulatory systems of an old and young mouse, pointed to GDF11 as a possible factor in conveying benefits to the old mouse. There is now some debate over why parabiosis works, however, casting doubt on the argument of beneficial factors in young blood. Similarly, there has been some back and forth in the research community regarding whether or not past work on GDF11 is as it appears to be, but the Elevian staff claim to have resolved the conflicts. In many cases, the best way to resolve a debate of this nature is to just forge ahead and try to build a therapy; that effort can pull in much greater funding more rapidly than the academic community can manage via the usual channels available to researchers.

Another item that caught my attention, and seems worthy of consideration, is that the infrastructure and drug discovery companies in our space of treating aging as a medical condition are the furthest ahead in terms of building out relationships with venture concerns, obtaining larger funding, and breaking ground on their larger and later projects. This may reflect the focus of groups like Juvenescence from the past couple of years, their approach to establish an initial presence in a field. Examples of this trend include In Silico Medicine and Ichor Therapeutics' portfolio company Antoxerene, both of which offer faster, cheaper discovery of small molecule drugs for any sort of use, but both of which happen to have founders very interested in aging and longevity over and above any of the myriad other uses for their technologies. In Silico Medicine in particular is clearly advancing by leaps and bounds in Asia as they gather support from the high-end venture groups there.

(I'll confess that I've never found the development of lower level biotechnological infrastructure all that interesting as a topic. Obviously it is vital, and acceleration of technological progress is achieved by making common tasks easier, faster, and cheaper. Someone has to do it, invest in it, and focus on it, but that someone will never be me. I am far more interested in specific implementations of rejuvenation therapies, the development groups who might end up using the infrastructure to build a given treatment).

San Francisco is ever a hub of connections for the venture and technology spaces. It is the base of operations and home for a sizable number of high net worth individuals, agents for other high net worth individuals, fund partners deploying sizable amounts of capital, successful founders turned angel investors, successful angel investors turned founders - all rubbing shoulders, bumping into one another at the supermarket, and two degrees of separation removed at most. It is through this very connected network that interest in the biotechnologies of rejuvenation has been spreading these past fifteen years, pushed along by the presence of the SENS Research Foundation in the Bay Area. This occurred slowly at first, given that the focus was initially philanthropic funding of research rather than startups, but much more rapidly these past few years now that the first rejuvenation biotechnology startups are arriving on the scene.

At a small gathering after the Juvenescence event, those attending included an older AI-focused entrepreneur-turned-investor who has a growing interest in biotechnology, and a recently successful young founder from the technology space who is now taking life science classes to get up to speed on what he considers to be his next area of interest. The next day I met with an angel investor who attended the Juvenescence event, and who is cheerfully incorporating biotech companies into his previously tech-company-heavy portfolio. This dynamic is similarly reflected in venture firms such as Y Combinator, Felicis Ventures, and (closer to our community) Kizoo Technology Ventures led by Michael Greve, among others. They are transitioning into biotechnology, and the interest in doing something about aging is a driving motivation for many involved. For others, it is the realization that successful rejuvenation therapies will lead to a market so enormous as to make a pittance of near everything that has come before. Self-interest is a machine to be harnessed in these matters: while fundamental research is very cheap, later commercialization and distribution of medical therapies to millions of patients is enormously expensive. We need the deep pockets to enter this space, and to pull in all of their allies and other interested parties, if we are to see a reasonable rate of progress in moving rejuvenation therapies from lab to clinic.

The only other alternative is some form of major, lasting revolution in the regulatory environment, as that is the dominant cause of cost and delay. Therapies could be brought to market just as safely as they are today at a fraction of the present cost; the majority of cost and time imposed by the FDA, EMA, and the like is entirely unnecessary, some of it the debris of regulatory capture used by larger pharmaceutical entities to suppress competition, some of it the consequences of bureaucrats going to any lengths to avoid negative press, even by the means of preventing most new technologies from ever being approved. I'm certainly in favor of great upheaval in the development of medical therapies, but tearing down the present edifice is a vast project, and arguably one that will be much less costly and difficult to undertake given the existence of the first rejuvenation therapies and the public demand for more.

A final thought on investors and the science of rejuvenation: most of the newcomers are still finding their way to an understanding of the science in this space. They cannot yet tell the difference between projects likely to produce significant gains in human life span, those based on repair of the damage that causes aging, and those that cannot in principle produce large gains, those based on, say, upregulation of stress responses, such as mTOR inhibitors. Investors are guided by potential for financial gains, but that metric is not in fact a great way to tell the difference between better and worse approaches to aging. The typical competently run medical biotechnology company is acquired or goes public before the final determination of effectiveness of their programs; perhaps somewhere just after the first human trial, or even prior to that when the market is hot. Companies can do this after showing marginal benefits, or even just potential for marginal benefits, with a therapy that will never produce large or reliable benefits in larger patient populations, and yet still realize large gains for the early investors. So this is a challenge, and an opportunity for patient advocates to make a difference - to help guide those people chasing gains into obtaining those gains by backing better rather than worse technologies.

Tau Impairs Both Mitochondrial Function and Quality Control

Researchers here show that tau protein, a feature of late stage Alzheimer's disease, causes issues with mitochondrial quality control mechanisms responsible for removing damaged or dysfunctional mitochondria. Since tau also harms the function of mitochondria, this is particularly pernicious, and may be a significant component of the cell death that follows tau aggregation. Mitochondrial dysfunction is a feature of most neurodegenerative diseases, causing cellular processes in the brain to falter for lack of energy, but the question of where it sits in the web of cause and consequence in relation to other disease mechanisms remains to be resolved. Is the case that Alzheimer's tends to occur more readily in people with worse age-related mitochondrial dysfunction, or does one or more of the other aspects of Alzheimer's, such as tau aggregation, produce the observed greater level of mitochondrial dysfunction as a downstream effect? Or both? This sort of question is surprisingly hard to answer in conditions that have many contributing causes.

Accumulation of clumps of tau is a well-established hallmark of Alzheimer's disease and other neurodegenerative disorders, as is the aggregation of damaged mitochondria, the powerhouse of a cell. However, the interaction between tau and mitochondria is still being explored, and new research has found an additional disruptive function of tau in terms of mitochondrial health. "It has long been known that there is an accumulation of abnormal mitochondria in neurodegenerative diseases, including Alzheimer's disease. More specifically, tau has previously been shown to impair different aspects of mitochondrial function, and here, we find that tau also impairs the degradation of mitochondria. This causes a toxic cycle whereby tau both damages mitochondria and then also prevents their removal."

One of the ways by which tau causes cell damage is by preventing the removal of damaged mitochondria, a process referred to as mitophagy. Normally, damaged mitochondria are trafficked to the lysosome (the waste remover of the cell) for destruction, by a molecule called Parkin, which moves from the intracellular fluid to the impacted mitochondria to start the trafficking process. However, researchers found tau impaired this process by interacting "aberrantly" with the Parkin protein in the intracellular fluid before it could reach the mitochondria, thereby preventing the removal process, and with damaging consequences for the cell.


PUM2 and MFF in the Dysregulation of Mitochondrial Fission in Aging

Mitochondria, the power plants of the cell, become dysfunctional over the course of aging. This is a general process in all mitochondria, and not the same thing as the severe mitochondrial DNA damage that occurs in only a few cells, but that has a widespread detrimental effect. In this more general mitochondrial malaise, there are changes in shape and important functions decline; energy-hungry tissues such as brain and muscle suffer as a consequence.

Mitochondria are the descendants of ancient symbiotic bacteria, and thus act much like bacteria in carrying out fission and fusion, and passing component parts around between one another. In recent years, researchers have found that imbalances between fission and fusion appear in aging, this impairs the ability of autophagic processes to remove damaged mitochondria, and that provoking more fission or less fusion slows aging in short-lived species. Researchers continue to investigate the mechanisms underlying this imbalance; the results noted here are an illustrative example of the progress taking place in this part of the field.

Mechanisms based on mRNA transcription, a very important step in gene expression, are a part of the complex regulatory mechanisms in our cells. RNA-binding proteins (RBPs) bind mRNA molecules and regulate their fate after gene transcription. In this study, scientists screened cells from old animals to identify any RBPs that change upon aging. The screening showed that one particular protein, Pumilio2 (PUM2), was highly induced in old animals. PUM2 binds mRNA molecules containing specific recognition sites. Upon its binding, PUM2 represses the translation of the target mRNAs into proteins.

Using a systems genetics approach, the researchers then identified a new mRNA target that PUM2 binds. The mRNA encodes for a protein called Mitochondrial Fission Factor (MFF), and is a pivotal regulator of mitochondrial fission - a process by which mitochondria break up into smaller mitochondria. Having high levels of MFF also allows the clearance of broken up, dysfunctional mitochondria, a process called mitophagy.

The study found that this newly identified PUM2/MFF axis is dysregulated upon aging. Evidence for this came from examining muscle and brain tissues of old animals, which were found to have more PUM2, and, consequently, fewer MFF proteins. This leads to a reduction of mitochondrial fission and mitophagy, and without the ability to chop up and remove smaller mitochondria, the aged tissues start accumulating bigger and unhealthy organelles.

But removing PUM2 from the muscles of old mice can reverse this. "We used the CRISPR-Cas9 technology to specifically target and inactivate the gene encoding for Pum2 in the gastrocnemius muscles of old rodents. Reducing Pum2 levels, we obtained more MFF protein and increased mitochondrial fragmentation and mitophagy. Notably, the consequence was a significant improvement of the mitochondrial function of the old animals."


Old Tissues Have Many Mutations, Even Absent Cancer

Cancer is the result of random mutational damage to nuclear DNA, but most such damage has no real effect, not even to the behavior of the affected cell. Cells in old tissues are riddled with mutations, but it is an open question as to how much this accumulated damage contributes to aging beyond cancer risk. Does it produce sufficient disarray in tissue function to be measured? A mutation capable of meaningfully altering cell behavior (a small subset of all possible mutations) can only have a noticeable affect when it occurs in many cells, a significant fraction of those present in a tissue. One slightly defective cell is a drop in the ocean, provided it isn't actively cancerous.

Many researchers consider that the outcome of clonal expansion of mutations in adult tissue can be achieved when the original mutation occurs in a stem cell of some kind. The mutation can spread with the long-term delivery of a supply of daughter somatic cells and their descendants. Along these lines, the studies noted in the article below raise the possibility that cancer-associated mutations can also grant this ability to spread through excessive replication, yet without immediately resulting in the production of a tumor.

The field lacks definitive studies and models that would enable researchers to put numbers to the contribution of mutational damage to degenerative aging and age-related diseases other than cancer. Clearly the boundary between production of cancer and production of functional damage isn't sharply drawn if expansion of mutations is a feature of the pre-cancerous state. Fixing the damage is usually the best way to proceed when answering this sort of question, but that is very hard to achieve for random DNA damage in isolation of all the other aspects of aging. Every cell needs custom work. More practically, delivering newly created, undamaged stem cell populations to replace old stem cell populations is a feasible form of future therapy, but it certainly doesn't isolate DNA damage as the only altered variable.

Mutations differ in normal and cancer cells of the oesophagus

Errors in DNA replication can alter a cell's DNA sequence. If such alterations occur early enough in embryonic development, the changes are inherited by all of an organism's cells. But if the alterations arise later in adult life, it is more difficult to track such changes in a small number of cells in a specific tissue, so the extent of these alterations in normal tissues is poorly understood. It is thought that cancer is initiated when cells acquire a minimum compendium of genetic alterations needed to trigger tumour formation. Understanding when such initiating mutations occur in normal cells is crucial for enabling reconstruction of the early events that lead to cancer.

Researchers have analysed the extent of mutations in human epithelial tissue from the healthy oesophagus, and how this relates to the processes that drive cancer development. They sequenced 74 cancer-associated genes in 844 tissue samples taken from the upper oesophagus of 9 healthy donors who differed in gender, age and lifestyle. For 21 of these samples, the authors also determined whole-genome sequences. A previous study assessing mutations in healthy skin cells reported between two and six mutations per million nucleotides of DNA. By contrast, here the mutations in oesophageal cells arose at a roughly tenfold lower rate. This difference is unsurprising, because skin cells are exposed to more DNA-damaging agents, such as ultraviolet light, than are oesophageal cells.

Instead, the surprise is that, compared with healthy skin, the healthy oesophagus has more mutations in cancer-associated genes. Moreover, at least a subset of these altered genes was under strong positive selection, meaning that the genetic alterations promoted cell proliferation, leading to the formation of cell clones. Compared with the samples from younger people, the overall number of mutations, the number of mutations in cancer-associated genes and the size of the clones were all greater in the samples from older people. The authors found that the donors' samples had an average of about 120 different mutations in NOTCH1, a known cancer-associated gene, per square centimetre of normal oesophageal tissue.

The clonal expansion of normal oesophageal cells after cancer-promoting genes have mutated seems to be necessary, but not sufficient, to drive cancer, so something else must happen to the cells for tumours to form. For example, gaining a large-enough number of alterations in cancer-promoting genes might be needed. Few of the mutations were present in all the cells of the normal clones, and many of the cancer-promoting mutations were often found in spatially distinct subclones. This suggests that none of the normal cells had acquired enough cancer-promoting alterations to start cancer formation.

More on TREM2 and Immune Function in Alzheimer's Disease

You might recall research published early last year on TREM2 as a possible regulator of immune cell clearance of amyloid in Alzheimer's disease. Researchers here provide a further update on their investigations of the role of TREM2 in this process. To the degree that the immune system falters in this task of clearing metabolic waste with age, and to the degree that this issue can be reversed or overridden, this may prove to be a useful approach to age-related protein aggregates in the brain, and their contribution to neurodegenerative disease. As is so often the case, however, a treatment cannot be immediately and straightforwardly constructed based on manipulation of TREM2. Its relationship with immune cell activity and the Alzheimer's disease state is complex.

A hallmark of Alzheimer's disease is the formation of toxic deposits in the brain, so-called plaques. Specialized immune cells termed microglia protect the brain by clearing it from these toxic debris. TREM2 is a key factor in activating microglia and thus serves as an important target for novel therapeutic approaches. To further explore these therapeutic options, scientists undertook a detailed analysis of disease development in mice with and without a functional TREM2 gene.

In mice with healthy TREM2, microglia cluster around small emerging plaques early in the disease process and prevent them from enlarging or spreading. Researchers were able to show that microglia are specifically attracted to amyloid plaques. They surround individual plaques and engulf them piece by piece. In contrast, in mice lacking TREM2, microglia were unable to carry out this important task. Therapeutic activation of TREM2 in an early stage of the disease could thus help counteract the formation of toxic amyloid-beta protein aggregates.

However, the study results also call for caution when implementing such a therapy. While TREM2 prevents plaque formation early in disease progression, it may have the opposite effect later on. In more advanced stages of the disease, the plaques grew faster in mice with functional TREM2 than in mice lacking the corresponding gene. The researchers discovered that this could be explained by the fact that TREM2 induces microglia to produce a substance called ApoE, which enhances aggregate formation. "Our study shows that we have to be extremely careful and investigate a new therapeutic approach thoroughly in animal models before testing it on humans. According to our findings, it could have dramatic consequences if we over-activate microglia. In the future, it will be important to treat Alzheimer's disease in a stage-specific manner."


Declining Autophagy Implicated in Tau Aggregation in the Aging Brain

Tau aggregation, the formation of solid deposits of altered tau protein called neurofibrillary tangles, is thought to be the most damaging of the processes underlying Alzheimer's disease. The earlier accumulation of amyloid-β only sets the stage for the later accumulation of altered tau. When looking at why protein aggregates such as amyloid-β and tau accumulate only in later life, one of many candidate mechanisms is the decline of autophagy that takes place with aging. Autophagy is the name given to a collection of cellular maintenance processes responsible for clearing out damaged structures and other unwanted waste, such as protein aggregates. A range of interventions shown to slow aging in laboratory species involve raised levels of autophagy: if cells are more aggressively maintained, there is less of a chance for damage and dysfunction in cellular processes to spread and cause further harm. The other side of the coin is that lower levels of autophagy mean more metabolic waste, more damaged components, and more downstream consequences.

Early in the course of Alzheimer's disease, neurons in the brain become clogged with toxic tau proteins that impair and eventually kill the neurons. A new study found that tau accumulates in certain types of neurons, probably because the cellular housekeeping system of autophagy is less effective in these neurons. Researchers have long known that neurodegenerative diseases like Alzheimer's affect some neurons but not others, even leaving neighboring neurons unharmed. But the reasons for this selectivity have been difficult to identify.

The new study was only possible because of new techniques that allow researchers to probe individual cells in the brain. Researchers detected signs that the components of a cellular cleaning system were less abundant in the neurons that accumulate tau proteins. To confirm the connection between the cleaning system and tau buildup, the researchers manipulated BAG3, a regulatory protein in autophagy, in mouse neurons. When the researchers decreased BAG3 levels in mouse neurons, tau piled up. But when BAG3 expression was enhanced, the neurons were able to rid themselves of excess tau.

The researchers have tantalizing, still unpublished data that the same housekeeping deficiencies found in vulnerable neurons occur with aging, which might explain the link between advanced age and Alzheimer's disease. "If we can develop therapies to support these natural defense mechanisms and stop tau from accumulating, then we might be able to prevent, or at least slow, the development of Alzheimer's and other tau-related neurodegenerative diseases."


Wary of the Beautiful Fairy Tale of Near Term Rejuvenation

One might compare this interview with researcher Leonid Peshkin to last year's discussion with Vadim Gladyshev. There is a spectrum of caution and pessimism regarding near term progress towards rejuvenation; the pessimists in the research and development communities are not all alike in their viewpoints, and nor do they all have the same take on the complexity of cellular metabolism as a hurdle to progress.

If a researcher thinks that small molecule drugs or gene therapies to alter the operation of metabolism into a state in which aging is slowed are the only way forward, then yes, it is reasonable to consider that progress will be slow and incremental. Metabolism is far from fully mapped, and thus the detailed progression of aging is also full of unknowns. Yet why take the hard path when there is an easier way forward? The whole point of the SENS approach to aging, based upon repair of root cause damage, is to bypass this complexity and lack of knowledge. Remove the known and well-catalogued damage at the root of aging, and a sizable fraction of the consequences will be repaired by the normal processes of tissue maintenance; we know this because we have the example of youthful individuals and their metabolism to draw on.

Of course, it is then possible to debate whether or not the short-term repair projects that can be achieved in the next ten to twenty years will produce large enough gains in life expectancy to enable people to live to see success in the long-term, harder repair projects. Senolytics, breaking of glucosepane cross-links, clearance of protein aggregates, cell replacement therapies, and more, will all be going concerns in the 2020s. But projects such as repair of stochastic mutations in nuclear DNA or damaged nuclear pore molecules in long-lived and critical populations of neurons are well beyond present capabilities.

An Interview with Dr. Leonid Peshkin

As a way of introduction, I'd like to offer a caricature of the currently popular sensationalist view in the field of aging: "We are the chosen generation. Singularity is near. Rejuvenation therapy is almost here. Not one, several a-la-carte: stem cells, factors from young blood, senolytics, Skulachev's ions, NAD, etc. Companies backed up by luminaries from business and science are already sorting out the remaining details, helped by the formidable force of AI technology called 'deep learning'." This fairy tale is beautiful, and deep in my heart, I hope I am mistaken, but I think that at the moment, this positive mysticism is not justified and is rather counterproductive. The excessive optimism is, unfortunately, standing in the way of progress, as I will try to explain.

There are many proposed models of aging, such as the Hallmarks of Aging, SENS, and the deleteriome. Which, if any, of these models do you believe reflects the reality of aging?

I would not want to take part in religious wars. People get very passionate and clash about often vaguely defined terms. Which of the observed hallmarks of aging, from the molecular to the organism levels, are correlates and which are causes of aging is hard to say. Biology has not yet matured to become an exact science. Perhaps owing to my training in quantitative science I take a "model" to mean a level of quantitative understanding that allows for "modeling"; that is, forecasting and answering "what if" questions. Such a model might not be ultimately expressed by a set of crisp human-readable mathematical formulae but rather a large set of tuned parameters in an artificial neural net or some other representation that has not yet been invented. It must, however, provide a way to assess the current state of an organism and predict its lifespan and healthspan in a stable environment, outside of a major perturbation, and then go further to allow for perturbations and adjust the predictions.

Today, I can't even say that there is an agreement in the field of what is a useful definition of "aging". I like "increase of hazard rate (i.e. the probability of dying) with time", which is admittedly a very mathematical notion - precise and not terribly useful. Inverting this formula, we get a curious metaphor - a life without aging can be imagined as a life where, say, once a year, you undergo a treatment that rejuvenates you a year in biological age, or, with some small but non-negligible probability, kills you. Life is a game of chance.

Do you believe that aging is a one-way process or something that is flexible and amenable to intervention?

It is both. Imagine one dramatic intervention: one day, we invent a way to cryo-protect a warm-blooded organism like ours so that it can undergo a freeze-thaw cycle without damage. Now, you are faced with a challenge to design a schedule that determines when, and in what size fractions, you'd like to use up your lifespan. While you are frozen, time stops. While you are alive, you age: the "deleteriome" kicks in, ionizing radiation wrecks your DNA, your defrosted friends and family du jour stress you out, etc. That's what things would look like ad absurdum, illustrating the tradeoffs.

Now, back to the interventions: I imagine a process not unlike a beauty salon, in which you do your nails and hair and get an occasional facelift; all of these are tradeoffs, even if people do not recognize it. Beauty treatments make you look younger at the moment, but cosmetics products may poison your skin and accelerate actual aging. There is evidence of such tradeoffs across organisms in nature; extending lifespan in many species can be accomplished at the expense of reproduction, and in cold-blooded organisms, you can multiply the lifespan several-fold by just cooling the environment down or slowing down metabolic processes in other ways. I believe that the first results will be not so much in giving people free tickets to longer lives but in making the tradeoffs more explicit, educating people and putting them in control of decision making.

Do you consider epigenetic alterations as a cause of aging or a downstream consequence?

Neither cause nor downstream. There is no linear causal chain with the two links of "aging" and "epigenetic alterations"; instead, there are loops and amplifiers in the circuits of aging. Epigenetic alterations have to be caused by something else; these, in turn, control many things. On the other hand, DNA damage is clearly pretty early in the causal network but is hard to undo. There is more hope to proofread and fix "epigenetic alterations". I am very much interested in this direction of research, so much so that we are planning an experiment looking at changes in the distributions of cell types in cell populations that make up young and old individuals. The expectation is that epigenetic alterations lead to de-differentiation and mis-differentiation of cells in old organisms, which could be characterized and further used as end-points for aging interventions.

Age-Related Oxidative Stress Contributes to Excess Cholesterol in the Liver

The presence of oxidative molecules in our biochemistry rises with aging, and cells react to this in many different ways. Internally to cells, this sort of damage can be rapidly repaired and brief bursts of oxidative molecule creation even serve as a signal for many necessary processes, such as the beneficial reactions to the stresses of exercise. Chronic oxidative stress produces dysfunction, however, whether that is via the production of toxic oxidized lipids or through through more direct means of causing cells to act in a harmful manner.

Chronic inflammation and mitochondrial dysfunction are two of the upstream causes of increased numbers of oxidative molecules. Among the downstream consequences can be found all sorts of detrimental cellular reactions, many of which are only poorly explored at best. The open access paper here is an example of the type. The best solution to this class of age-related problem is to go after the upstream causes, though mitochondrially targeted antioxidants appear to provide a beneficial suppression of oxidative stress in at least some situations.

The production of reactive oxygen species (ROS) is progressively increased in aging and is one of the key factors in cellular damage. It is known that ROS, including free radicals and peroxides, adversely affects cells and tissues and causes an imbalance in the biological system, contributing to the development of many aging-related diseases. In addition, oxidative stress plays an important role in hepatic disease. Aging increases fibrotic responses and is also associated with the development of a variety of liver diseases including nonalcoholic fatty liver disease and alcoholic liver disease. In particular, the prevalence of nonalcoholic fatty liver disease tends to increase with age, and thus, aging and lipid metabolism in the liver may be closely related. In addition, evidence suggests that increased oxidative stress due to various factors leads to increased lipid accumulation in the liver, while decreased oxidative stress has a lipid-lowering effect in hepatocytes.

Lipid supply to liver tissue consists of three main pathways: dietary intake, peripheral lipolysis, and de novo lipogenesis. Fatty liver occurs when the lipid supply exceeds the hepatic lipid removal. In many previous studies, triglyceride and cholesterol metabolism disorders and accumulation have been reported to be closely related to aging. For example, in the senescent-associated mouse, the cholesterol content in the liver was increased compared with control mice. In this study, we investigated the mechanisms for the increase in cholesterol accumulation during aging. We found that the increased ROS in aging plays an important role for the accumulation of cholesterol in the liver by increasing cholesterol uptake and cholesterol synthesis via increasing glucose uptake.

The mRNA expression of GLUT2, GK, SREBP2, HMGCR, and HMGCS, genes for cholesterol synthesis, was gradually increased in liver tissues during aging. When we treated HepG2 cells and primary hepatocytes with the ROS inducer, H2O2, lipid accumulation increased significantly compared to the case for untreated HepG2 cells. H2O2 treatment significantly increased glucose uptake and acetyl-CoA production, which results in glycolysis and lipid synthesis. Treatment with H2O2 significantly increased the expression of mRNA for genes related to cholesterol synthesis and uptake. These results suggest that ROS play an important role in altering cholesterol metabolism and consequently contribute to the accumulation of cholesterol in the liver during the aging process.


Delivery of Extracellular Vesicles for Skin Repair and Rejuvenation

To what degree can skin be restored to a more youthful state just by changing cell behavior? That question will be explored comprehensively in the years ahead, and not just for skin. Many research groups are taking the approach of harvesting extracellular vesicles from stem cells and delivering them into tissues, a potential form of therapy that appears to produce many of the same benefits as first generation stem cell transplants, and with less expense and complexity.

What fraction of these benefits are a matter of overriding unfortunate cellular reactions to damage, or putting damaged cells back to work, hopefully without reaching the threshold at which this would produce an increased cancer risk? How much is a genuine clean-up of metabolic waste or damaged components in cells? That remains to be determined, but it is worth bearing in mind that there are forms of metabolic waste and cell damage that our biochemistry cannot deal with, no matter how fired up it might be. Ultimately, the research community must do better than simply instructing our cells to work harder. Tools must be provided to break down that waste, irreparably damaged stem cells replaced, and more.

Stem cells have attracted great interest from the scientific community since their discovery. Their capacity to differentiate into various cell types and hence provide tissue repair made them promising tools in the treatment of such pathologies as neurodegenerative disorders, organ failure, and tissue damage. However, stem cells such as mesenchymal stem/stromal cells (MSCs) exert their functions via paracrine effects and not by the replacement of dead cells.

The term secretome refers to the complex mixture of factors released by virtually all cell types, including stem cells, to the extracellular space. Once released by stem cells, this combination of different classes of molecules can modify microenvironments by controlling inflammation as well as inducing selective protein activation and transcription. This secreted milieu of molecules may culminate in tissue regeneration. Recent evidence about this paracrine mechanism has opened up a new paradigm in stem cell therapy and stimulated the search for strategies that explore the concept of "cell therapy without cells."

The most well-studied and dynamic part of the growing field of secretomics is extracellular vesicles (EVs). EVs represent an important fraction of virtually any cell type's secretome. Extensive research is currently being conducted to elucidate the healing potential of stem cell EVs in numerous disease processes. EVs released by stem cells to the extracellular space have been shown to improve vascularization, immunomodulation, and cardiac and central nervous system regeneration.

Stem cell-conditioned media from endothelial precursor cells differentiated from human embryonic stem cells have been used in skin rejuvenating research with interesting results. The injection of conditioned media from those cells improved the aspect of skin wrinkles and skin aspect in women. UV light damage and aging affect extracellular matrix collagen and elastin depots, both of which are key in the prevention of skin dehydration as well as in firmness and elasticity preservation. The beneficial effects of stem cell EVs for cellular matrix maintenance and collagen production as described previously could contribute to this effect, considering that vesicles are important components of stem cell-conditioned media.

Furthermore, reports have suggested that purified stem cell EVs could play a role in rejuvenating skin cells. A report indicated that EVs from induced pluripotent stem cells (iPSCs) could restore the function of aged human dermal fibroblasts. The authors reported that dermal fibroblasts pretreated with iPSC EVs resisted photoaging with UVB and did not overexpress matrix-degrading enzymes MMP-1/3 but, on the contrary, displayed a high expression of collagen I, as young fibroblasts do. Other researchers studied the capacity of human umbilical cord stem cell EVs to rejuvenate skin by modulating collagen production and permeation. They also investigated whether EVs acceptance could accelerate fibroblast proliferation. Not only did skin cells proliferate more after EVs endocytosis, but a better production of collagen and elastin in human skin models was also observed in their study. Altogether, these studies indicate that stem cell EVs could be good candidates for therapeutic strategies against aging.


Is it Safe to Greatly Reduce LDL Cholesterol, Far Below Normal Levels?

The dominant approach to slowing atherosclerosis remains a mix of pharmaceuticals that can, separately, reduce blood pressure and LDL cholesterol (LDL-C) in the bloodstream. In the latter case, new therapies such as PCSK9 inhibitors and improved combinations of statins are capable of doing far more than just return raised LDL-C to normal levels. It is in fact possible to reduce blood cholesterol to something like a half or quarter of normal levels, and this produces incrementally greater benefits in reduction of atherosclerosis risk. But is it safe over the long term? And if it is, why did we evolve to have the observed normal levels of cholesterol in blood?

Atherosclerosis is the build up of fatty plaques that narrow and weaken blood vessels, ultimately leading to a fatal rupture of some form. Raised blood pressure accelerates this process through mechanisms that are incompletely explored - but it is obviously the case that, at later stages, more pressure and weaker blood vessels combines to increase the risk of fatal structural failure. Cholesterol is another input, arriving from the bloodstream. The final input is the activity of the immune system, and local inflammatory signaling, as the immune cells called macrophages attempts to clean up cholesterol from blood vessel tissues and return it to the liver to be disposed of.

Atherosclerotic plaques start and grow due to the presence of damaged, oxidized cholesterol more than overall cholesterol, but the more cholesterol in total, the more oxidized cholesterol is mixed in. That proportion increases with age, as rising levels of oxidative molecules throughout the body lead to ever more oxidative damage to molecules. Macrophages respond to the presence of cholesterol, arrive, become overwhelmed by oxidized cholesterol, and become inflammatory foam cells or die. In either case they produce signaling that leads to a further influx of macrophages, a feedback loop that only worsens with time. The bulk of atherosclerotic deposits is made up of the debris of dead cells and the cholesterol they failed to clear away, a significant fraction of it oxidized cholesterol.

Thus lower blood cholesterol is good in the sense that it will slow down this process by reducing one of the inputs. Unfortunately it doesn't appear to significantly reverse atherosclerosis. Established atherosclerotic plaques remain, and the fatal end result is only put off to some degree, even for the very dramatic reductions in blood cholesterol discussed here. Better approaches are needed, such as ways to destroy oxidized cholesterol, or make macrophages resistant to oxidized cholesterol, or otherwise improve the process by which macrophages mine cholesterol from plaques and export it back to the liver. The past twenty years has seen a fair amount of innovation on the latter option, but sad to say that it has failed in human trials, even while producing as much as a 50% reversion of plaque in mice.

Is very low LDL-C harmful?

LDL-C is deposited in the arterial wall and promotes the inflammation process through the attraction of monocytes and macrophages at the site of cholesterol deposition, thus resulting in the development of atherosclerotic plaques and overt cardiovascular (CV) disease. An abundance of evidence has shown a linear relationship of LDL-C levels with the risk for CV events. Several lipid-lowering treatments such as statins, ezetimibe and the novel proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors were found to offer significant benefits in the reduction in LDL-C and importantly in the amelioration of the overall CV risk of patients with hyperlipidemia with or without CV disease.

Towards this direction, the European Society of Cardiology and the European Society of Atherosclerosis recommend the reduction in LDL-C to lower than 70 mg/dl or a reduction of at least 50% if the baseline values are between 70 and 135 mg/dl in very high-risk patients, to lower than 100 mg/dl or a reduction of at least 50% from baseline values between 100 and 200 mg/dl in high-risk patients, and to less than 115 mg/dl in low to moderate risk patients. The 2017 American Association of Clinical Endocrinologists and American College of Endocrinology Guidelines for Management of Dyslipidemia and Prevention of Cardiovascular Disease suggest even lower LDL-C targets of <100 mg/dl, <70 mg/dl, and <55 mg/dl, in high, very high, or extreme risk diabetic patients.

The necessity for the reduction in LDL-C levels to provide significant CV beneficial effects has been shown and is recommended by all international guidelines. However, there are concerns for the optimal lower limit in which LDL-C can be reduced to achieve optimal CV benefit without causing potential adverse events. The purpose of this review is to present available data for the safety of reducing LDL-C to low or very low levels as it comes from studies of lipid-lowering drugs that achieved such levels.

In general, intensive lipid-lowering studies with statins showed that there is no increased risk of adverse events with reducing LDL-C to levels of approximately 40-50 mg/dl. The most important data for reducing LDL-C to such levels are provided from PCSK9 inhibitors studies where remarkable reductions in LDL-C levels were achieved and no increased rates of adverse events were noted with evolocumab. The slightly concerning findings with alirocumab in the ODYSSEY LONG TERM trial were not verified in the ODYSSEY OUTCOMES study. More importantly, the potential neurocognitive decline with low LDL-C was not observed in several post-hoc analyses and in the EBBINHAUS trial that was specifically designed to evaluate such events. However, it has to be noted that in most trials, the follow-up period and the exposure of the patients in low LDL-C was rather short and trials with longer study periods are needed to unveil potential harms.

Last, higher incidences of hemorrhagic stroke and cancer were not observed in these studies, even at very low LDL-C levels. In conclusion, reduction of LDL-C to less than 50 mg/dl seems safe and provides greater CV benefits compared with higher levels. Data for achieved LDL-C lower than 20-25 mg/dl is limited, although findings from the above mentioned studies are encouraging. However, further evaluation is needed for future studies and post-hoc analyses.

More Evidence for Excess Fat Tissue to Contribute to Hypertension

Hypertension, or increased blood pressure, is one of the more important ways in which the low-level molecular damage of aging is converted into high-level structural damage to tissues. Hypertension produces increased rupture of capillaries and other forms of pressure damage to delicate structures of the brain and other organs, resulting in loss of function and, ultimately, death. It also accelerates the progression of atherosclerosis, the creation of fatty plaques that weaken and narrow blood vessels, with the end result of stroke or heart attack as an important blood vessel suffers structural failure.

Being overweight or obese is strongly associated with risk and degree of hypertension. The underlying mechanisms are easy to speculate on: the chronic inflammation produced by visceral fat tissue causes dysfunction in the smooth muscle cells that control blood vessel dilation and constriction, for example. That breaks the feedback mechanisms controlling blood pressure, leading to hypertension. The diet needed to become overweight likely contributes to greater cross-link formation, stiffening blood vessel tissues to produce much the same outcome. And so forth through a laundry list of other low-level damage that manifests in blood vessel walls.

Among the cardiovascular disease (CVD) risk factors, age is considered as the most important predictor of CVD events and hypertension is a major cause of CVD mortality. Age-related increase in blood pressure (BP) is recognized as a universal feature of human aging. Previous epidemiological surveys have shown a progressive increase in systolic blood pressure (SBP) with age, whereas diastolic blood pressure (DBP) also initially increases with age but falls at latter ages. Thus, effective control of BP is essential for improving population health.

Studies of BP associated with adiposity-related genetic variants and controlled trials of weight loss interventions have established the causal relationship between adiposity and BP. Regardless of age and other unmodifiable CVD risk factors such as sex and race, there are many risk factors that are manageable and can be controlled through lifestyle modification, including reduction of obesity. However, there are inconsistencies as to whether a general or central adiposity is more strongly associated with BP and different opinions about which variable is the strongest predictor of BP.

The present study aimed to investigate how BP and body composition change within different age groups and their correlation across the adult age span. We also investigated the contribution of body composition measures (including body mass index (BMI), lean mass percent (LM%), and visceral fat rating (VFR) to the age-related alteration of BP across ten 5-year age groups ranging from 18-79 years in a sample of healthy Chinese adults. We demonstrated that mean SBP showed an age-related increase and mean DBP showed an inverted U-shape across the age span, and this trend was closely associated with the age-related body composition changes. Furthermore, we found that the association between BP and body composition indices was weaker in the elderly compared to the younger subjects.

As demonstrated in our study, all measures of general obesity, central obesity, and LM% were correlated to BP at the whole population level, and among them the relationships with BP were similar across most of the body composition indices. Some studies have suggested that general adiposity was more strongly correlated with BP, while other studies suggested central or visceral adiposity was more strongly correlated with BP than general adiposity. In this study, we didn't find significant differences between these two kinds of obesity indices.

To examine whether body composition was a factor influencing BP throughout the whole adult age span, we further analyzed the association of BP with BMI, LM% and VFR in each specific age-group (at 5-year ranges). After adjustment for education level, smoking status, alcohol consumption, and residential location, BMI and VFR were positively associated with BP in each age group, suggesting that adiposity was an important risk factor for the increased BP, whereas LM% was negatively associated with BP, the latter indicating its protective effect on BP. The correlation between BP and all these three measures (BMI, LM%, and VFR) was weaker in the elderly than younger adults. Thus, as demonstrated by our study, we may infer that factors associated with increased BP may be more complicated in the elderly compared to the younger age groups.


Protein Aggregation versus Infection Hypotheses of Alzheimer's Disease

The amyloid hypothesis has dominated the past twenty years of failed attempts to build therapies to treat Alzheimer's disease. However, it is only very recently that immunotherapies and other methods of reducing amyloid-β levels in the aging brain have started to show signs of working. As a consequence, the field is in a state of some upheaval when it comes to choice of strategy going forward. Alternative views of Alzheimer's and its development have emerged and gained enough support to raise sufficient funds to compete. In the long run, this is all to the good, I think. A diversity of approaches always beats out a top-down monoculture when it comes to finding viable paths forward. The open access paper noted here examines a few different hypotheses that have risen to prominence.

In this review, we focus on four Alzheimer's disease (AD) hypotheses currently relevant to AD onset: the prevailing amyloid cascade hypothesis, the well-recognized tau hypothesis, the increasingly popular pathogen (viral infection) hypothesis, and the infection-related antimicrobial protection hypothesis. In briefly reviewing the main evidence supporting each hypothesis and discussing the questions that need to be addressed, we hope to gain a better understanding of the complicated multi-layered interactions in potential causal and/or risk factors in AD pathogenesis.

As a defining feature of AD, the existence of amyloid deposits is likely fundamental to AD onset but is insufficient to wholly reproduce many complexities of the disorder. A similar belief is currently also applied to hyperphosphorylated tau aggregates within neurons, where tau has been postulated to drive neurodegeneration in the presence of pre-existing Aβ plaques in the brain.

Although infection of the central nervous system by pathogens such as viruses may increase AD risk, it is yet to be determined whether this phenomenon is applicable to all cases of sporadic AD and whether it is a primary trigger for AD onset. Lastly, the antimicrobial protection hypothesis provides insight into a potential physiological role for Aβ peptides, but how Aβ/microbial interactions affect AD pathogenesis during aging awaits further validation. Nevertheless, this hypothesis cautions potential adverse effects in Aβ-targeting therapies by hindering potential roles for Aβ in anti-viral protection.

Unlike familial AD, sporadic AD may evolve from a combination of various genetic and environmental factors. Neuroinflammation, tau pathogenesis, and viral infection have all been implicated to play important roles in AD; however, these factors do not appear to be pathogenic triggers that are specifically relevant to AD. Thus, specific causal mechanisms that drive AD onset have yet to be clearly defined, which may lead to the identification of new therapeutic targets. It is now widely accepted that sporadic AD is a complicated syndrome.


The Harm Done by Senescent T Cells

Senescent cells accumulate with age in all tissues, and their presence is one of the root causes of aging. Cells become senescent in large numbers at all ages, and under a variety of circumstances: toxins, wound healing, ordinary somatic cells reaching the Hayflick limit, random mutational damage to important genes, and so forth. Senescence irreversibly shuts down cellular replication, making it a useful defense against cancer. Near all newly senescent cells are destroyed quickly. They either self-destruct or they are destroyed by the immune system, but both paths to a reliable natural clearance of senescent cells falter with the damage and dysfunction of aging.

Lingering senescent cells that have evaded destruction never rise to more than a few percent of all cells by number, even in very late life, but that is more than enough to produce major disruption to tissue function. Senescent cells secrete a potent mix of signals that remodel the extracellular matrix, encourage nearby cells to become senescent, produce chronic inflammation and immune system overactivation, and generally make a mess of things in many other ways. This is particularly disruptive for regenerative capacity, even though senescent cells are necessary for wound healing: their activity is generally useful in the short term for specific circumstances like this, it is when the signaling continues for the long term that the problems arise.

Immune cells, such as the T cells of the adaptive immune system, can also become senescent. Since these cells roam the body, the detrimental consequences can be broad and varied, unlike the case for senescent cells that reside in a given organ. Some of those consequences are examined in the open access review paper noted below. Roaming or not, it is the case that selective destruction of these cells via some form of senolytic therapy will provide benefits. We might think of the signals produced by senescent cells as a mechanism that actively maintains a more aged, damaged state of the body and brain. Destroying these cells is a narrow form of rejuvenation, turning back one of the causes of aging wherever it can be achieved.

The impact of senescence-associated T cells on immunosenescence and age-related disorders

Immunosenescence is age-associated changes in the immunological functions, including diminished acquired immunity against infection, pro-inflammatory traits, and increased risk of autoimmunity. The proportions of memory-phenotype T cells in the peripheral T cell population steadily increase with age, but the relationship between this change and immunosenescent phenotypes remains elusive. Recently, we identified a minor memory-phenotype CD4+ T cell subpopulation that constitutively expressed PD-1 and CD153 as a bona fide age-dependent T cell population; we termed these cells senescence-associated T (SA-T) cells. SA-T cells exhibit characteristic features of cellular senescence, with defective T cell receptor-mediated proliferation and T cell cytokine production.

The T cell receptor (TCR) responsiveness of the overall CD4+ T-cell population, in terms of proliferation and regular cytokine production, diminished gradually with age. Our careful studies, however, revealed that these effects were attributed primarily to the increase in the proportions of SA-T cells with age, given that the residual naïve and PD-1- (CD153-) MP CD4+ T cells in aged mice exhibited TCR responsiveness comparable to those from young mice. Senescent cells tend to resist apoptosis; consistent with this, SA-T cells were quite stable over long-term culture, probably accounting for the progressive accumulation of SA-T cells with age despite their defective proliferation capacity.

The age-dependent increase in SA-T cells could be due to CD4+ T cell-intrinsic effects or to the tissue environment of aged individuals. We found that the naïve CD4+ T cells transferred from young mice robustly proliferated in an aged host environment and underwent significant conversion to SA-T cells, whereas in young hosts, the same T cells barely proliferated and generated few SA-T cells. Thus, the aged, but not young, host environment plays a crucial role in the development of SA-T cells from naïve CD4+ T cells.

Accumulating evidence indicates that the SA-T cells are markedly increased in the tissues under persisted inflammation, often in association with the tertiary lymphoid tissues, of chronic inflammatory disorders. Recent evidence indicates that the selective elimination of tissue senescent cells leads to a significant improvement of age-associated tissue dysfunctions with prolonged lifespan. Consequently, tissue senescent cells are emerging as a crucial target for preventive and therapeutic intervention of age-related chronic disorders. Targeted elimination of SA-T cells represents a promising strategy for controlling chronic inflammatory disorders and possibly cancer.

Persistent Chronic Inflammation Raises the Risk of Neurodegenerative Disease

In this open access paper, the authors present evidence for chronic inflammation to contribute to the development of neurodegenerative disease. A great deal of research into the late stage disease state robustly connects inflammation to pathology, and given the risk factors for neurodegeneration, such as excess visceral fat tissue, it is entirely reasonable to think that inflammation is important. It accelerates the development of many other age-related conditions, after all. Less work has been carried out on the early stages of development of neurodegenerative diseases in humans, however, due to the lack of good data sets that span the necessary decades of time. There are already many good reasons to minimize chronic inflammation throughout life, to as great a degree as is possible. This one can be added to the stack.

Although it has become clear over the last several decades that inflammation plays a role in the pathogenesis of Alzheimer's disease and other forms of dementia, the precise nature and temporal characteristics of the neurodegeneration-inflammation relationship have remained largely unknown. Several lines of research have identified inflammation, both within the brain and within the periphery, as a potential driver of neurodegenerative brain changes and cognitive decline. Chronic low-grade inflammation, in particular, has received considerable attention, as translational studies suggest that it may play a causal role in dementia, late-life cognitive decline, and a number of other age-related phenotypes.

Although evidence from animal models indicates that chronic inflammation can perpetuate, or even initiate, neurodegenerative changes, this hypothesis has been challenging to examine in human studies. This is largely due to a lack of longitudinal data on inflammatory biomarkers in cohort studies which examine neurocognitive outcomes in older adults. In a recently published study of participants from the Atherosclerosis Risk in Communities (ARIC) Cohort, we were able to clarify the relationship between long-term (21-year) patterns of systemic inflammation and late-life neurodegenerative changes.

In this study, we found that individuals who both demonstrated elevated inflammation before or during middle adulthood and maintained high levels of inflammation over the subsequent two decades had greater white matter hyperintensity volume and reduced white matter microstructural integrity as older adults, compared to those who maintained low levels of inflammation. These findings support the idea that systemic inflammation can initiate or perpetuate neurodegenerative brain changes which underlie cognitive impairment and dementia.


Claiming Cellular Senescence for the Hyperfunction Theory of Aging

This mildly infuriating commentary well illustrates just why it is that theories of aging are so very diverse. Even a mechanism as well understood as cellular senescence can be fairly convincingly argued into one camp or another. For those who see aging as damage accumulation, lingering senescent cells are clearly a form of damage, a byproduct of normal metabolism that grows slowly over time and produces tissue dysfunction in proportion to the number of such cells. For those who consider the hyperfunction theory of aging, in which aging is the result of developmental programs failing to shut down in adult life, it is fairly easy to argue that the prevalence of cellular senescence in old people is an embryonic development mechanism or wound healing mechanism run wild. Cellular senescence does indeed play important roles in those circumstances.

Senolytics are drugs that extend lifespan and delay some age-related diseases by killing senescent cells. I want to draw your attention to the paradoxes associated with senolytics, which argue against the dogma that says aging is a functional decline caused by molecular damage. This dogma predicts that senolytics should accelerate aging. If aging is caused by loss of function, then killing senescent cells would be expected to accelerate aging, given that dead cells have no functionality at all. Instead, however, senolytics slow aging, which highlights a contradiction in the prevailing dogma.

The theory of hyperfunctional aging addresses this paradox. Killing senescent cells is beneficial because senescent cells are hyperfunctional. The hypersecretory phenotype or Senescence-Associated Secretory Phenotype (SASP) is the best-known example of universal hyperfunction. Most such hyperfunctions are tissue-specific. For example, senescent beta cells overproduce insulin and thus activate mTOR in hepatocytes, adipocytes, and other cells, causing their hyperfunction, which in turn leads to metabolic syndrome and is also a risk factor for cancer. SASP, hyperinsulinemia and obesity, hypertension, hyperlipidemia and hyperglycemia are all examples of absolute hyperfunction (an increase in functionality).

In comparison, relative hyperfunction is an insufficient decrease of unneeded function. For example, protein synthesis decreases with aging, but that decrease is not sufficient. In analogy, a car moving on the highway at 65 mph is not "hyperfunctional." But if the car were to exit the highway and enter a residential driveway at only 60 mph it would be "hyperfunctional," and stopping that car would likely prevent damage to other objects. Similarly, killing hyperfunctional cells can prevent organismal damage. Senolytics eliminate hyperfunctional cells, which otherwise damage organs.


A Selection of Recent News in Parkinson's Disease Research

Today I'll note a selection of recent news from the Parkinson's disease research community. Alzheimer's disease may be where the lion's share of funding goes when it comes to research and development related to neurodegenerative conditions, but work on Parkinson's disease is nonetheless well funded and diverse. This condition is characterized by aggregation of α-synuclein and the death of a small but vital population of dopamine generating neurons. The loss of those neurons results in the loss of motor control observed in patients, but there is a great deal of other damage done to the operation of the brain as a result of abnormal biochemistry downstream of α-synuclein aggregation.

Setting aside the older pharmaceuticals that do little but slow the condition or mask the symptoms, the dominant approaches to development of new therapies involve replacement of the lost dopamine neurons and clearance of α-synuclein. However, there are plenty of other places in which researchers have sought to intervene, in mechanisms that may or may not be downstream of α-synuclein. For example, it was recently demonstrated that cellular senescence in glial cells in the brain contributes meaningfully to the progression of Parkinson's - and thus near future senolytic therapies may produce patient benefits here as in many other age-related conditions. It is also the case that age-related decline in mitochondrial function accelerates the loss of neurons in Parkinson's disease. Where Parkinson's is connected with mutations, such as in the parkin gene, these are mechanisms affecting the maintenance of mitochondria.

Parkinson's disease is similar at the high level to other major neurodegenerative conditions: aggregation of damaging proteins; abnormal inflammatory behavior of the immune system in the brain; faltering mitochondrial function. The lower level details are wildly different, but the theme is the same. To talk about curing any neurodegenerative condition is to talk about curing aging. These conditions are the result of forms of molecular damage and waste buildup that cause aging itself; they can only be effectively dealt with by repairing this damage, and preferably early enough to prevent it from ever reaching pathological levels.

A Proposed Roadmap for Parkinson's Disease Proof of Concept Clinical Trials Investigating Compounds Targeting Alpha-Synuclein

The convergence of human molecular genetics and Lewy pathology of Parkinson's disease (PD) have led to a robust, clinical-stage pipeline of alpha-synuclein (α-syn)-targeted therapies that have the potential to slow or stop the progression of PD and other synucleinopathies. To facilitate the development of these and earlier stage investigational molecules, the Michael J. Fox Foundation for Parkinson's Research convened a group of leaders in the field of PD research from academia and industry, the Alpha-Synuclein Clinical Path Working Group. This group set out to develop recommendations on preclinical and clinical research that can de-risk the development of α-syn targeting therapies.

This consensus white paper provides a translational framework, from the selection of animal models and associated endpoints to decision-driving biomarkers as well as considerations for the design of clinical proof-of-concept studies. It also identifies current gaps in our biomarker toolkit and the status of the discovery and validation of α-syn-associated biomarkers that could help fill these gaps. Further, it highlights the importance of the emerging digital technology to supplement the capture and monitoring of clinical outcomes. Although the development of disease-modifying therapies targeting α-syn face profound challenges, we remain optimistic that meaningful strides will be made soon toward the identification and approval of disease-modifying therapeutics targeting α-syn.

Improved stem cell approach could aid fight against Parkinson's

Scientists have taken a key step towards improving an emerging class of treatments for Parkinson's disease. It addresses limitations in the treatment in which, over time, transplanted tissue can acquire signs of disease from nearby cells. It could aid development of the promising treatment - known as cell replacement therapy - which was first used in a clinical trial this year. Experts hope the approach, which involves transplanting healthy cells into parts of the brain damaged by Parkinson's, could alleviate symptoms such as tremor and balance problems.

Researchers have created stem cells - which have the ability to transform into any cell type - that are resistant to developing Parkinson's. They snipped out sections of DNA from human cells in the lab using advanced technology known as CRISPR. In doing so, they removed a gene linked to the formation of toxic clumps, known as Lewy bodies, which are typical of Parkinson's brain cells. In lab tests, the stem cells were transformed into brain cells that produce dopamine - a key brain chemical that is lost in Parkinson's - in a dish. The cells were then treated with a chemical agent to induce Lewy bodies. Cells that had been gene-edited did not form the toxic clumps, compared with unedited cells, which developed signs of Parkinson's.

"We know that Parkinson's disease spreads from neuron-neuron, invading healthy cells. This could essentially put a shelf life on the potential of cell replacement therapy. Our exciting discovery has the potential to considerably improve these emerging treatments."

Parkinson's disease protein buys time for cell repair

Parkin is absent or faulty in half the cases of early onset Parkinson's disease, as well as in some other, sporadic cases. In a healthy brain, Parkin helps keep cells alive, and decreases the risk of harmful inflammation by repairing damage to mitochondria, which are responsible for supplying energy to cells. Damaged mitochondria could trigger the cell's internal death machinery, which removed unwanted cells by a cell death process termed apoptosis.

"We discovered that Parkin blocks cell death by inhibiting a protein called BAK. BAK and a related protein called BAX are activated in response to cell damage, and begin the process of destroying the cell - by dismantling mitochondria. This ultimately drives the cell to die, but low-level mitochondrial damage has the potential to trigger inflammation - warning nearby cells that there is potential danger."

The team showed that Parkin restrains BAK's activity when mitochondria are damaged. Parkin tags BAK with a tiny protein called ubiquitin. With normal Parkin, BAK is tagged and cell death is delayed. Parkin 'buys time' for the cell, allowing the cell's innate repair mechanisms to respond to the damage. Without Parkin - or with faulty variants of Parkin that are found in patients with early-onset Parkinson's disease - BAK is not tagged and excessive cell death can occur. This unrestrained cell death may contribute to the neuronal loss in Parkinson's disease.

Results from a Pilot Human Trial of Senolytics versus Idiopathic Pulmonary Fibrosis

Researchers here report on results from an initial pilot trial of the use of a senolytic therapy to treat idiopathic pulmonary fibrosis. The data is perhaps much as expected for a first pass at removing senescent cells associated with a specific condition, using the tools available today: a starting point, benefits observed, but definitely room for improvement. The particular senolytic combination used here is cheap and readily available and can remove as much as half of senescent cells in some tissues in mice, but the degree of clearance varies widely by tissue type, and the optimal human dose is yet to be determined. Typically the next trial following an initial feasibility study will test a range of doses.

The past few years of animal data have indicated that the inflammatory signaling of senescent cells, the senescence-associated secretory phenotype (SASP), plays an important role in producing and maintaining age-related fibrosis in multiple tissues, but may not be the only process involved. Fibrosis is an outcome of disarray in regenerative and tissue maintenance, in which scar-like connective tissue is laid down in place of correctly formed tissue. Organ function is degraded as a result. In the case of idiopathic pulmonary fibrosis death follows within a few years of diagnosis, as the lungs fail.

Cellular senescence is a key mechanism that drives age-related diseases, but has yet to be targeted therapeutically in humans. Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal cellular senescence-associated disease. Selectively ablating senescent cells using dasatinib plus quercetin (DQ) alleviates IPF-related dysfunction in bleomycin-administered mice.

A two-center, open-label study of intermittent DQ (D:100 mg/day, Q:1250 mg/day, three-days/week over three-weeks) was conducted in 14 participants with IPF to evaluate feasibility of implementing a senolytic intervention. The primary endpoints were retention rates and completion rates for planned clinical assessments. Secondary endpoints were safety and change in functional and reported health measures. Associations with the senescence-associated secretory phenotype (SASP) were explored.

The retention rate was 100% with no DQ discontinuation; planned clinical assessments were complete in 13 of the 14 participants. One serious adverse event was reported. Non-serious events were primarily mild-moderate, with respiratory symptoms (16 events), skin irritation/bruising (14 events), and gastrointestinal discomfort (12 events) being most frequent. Physical function evaluated as 6-minute walk distance, 4-minute gait speed, and chair-stands time was significantly and clinically-meaningfully improved. Pulmonary function, clinical chemistries, frailty index (FI-LAB), and reported health were unchanged. DQ effects on circulating SASP factors were inconclusive, but correlations were observed between change in function and change in SASP-related matrix-remodeling proteins, microRNAs, and pro-inflammatory cytokines.

IPF appears to be relentlessly progressive: in large IPF drug trials, no improvements in 6-minute walk distance have been observed in the placebo-control arms. Pulmonary function in this IPF patient population did not change during the course of this preliminary study. It is likely that in this pilot exploration, the follow-up period is too short and the sample size too modest to assess effects on long-term trajectories, especially in a complex chronic disease such as IPF. If resolution of pulmonary scarring and fibrosis does indeed occur, it may take considerable time after clearance of senescent cells from the lung.


The Prospects for Cell Therapy to Restore Lost Neurons in Parkinson's Disease

Generating and transplanting dopamine-generating neurons into the brains of Parkinson's disease patients, to replace the cells destroyed by processes such as aggregation of α-synuclein, is one of the longer-running lines of development in modern cell therapy research. While the regenerative medicine community has advanced a long way past the first, mixed attempts at treating Parkinson's disease in this way, a great deal of work yet lies ahead in order to produce a reliable approach to the replacement of damaged cells. Most of the challenges are relevant to all attempts to introduce new, functional cell populations into the aging body: ensuring the cells survive; preventing the age-damaged environment from overwhelming any benefits that are produced; establishing cost-effective sources of cells, preferably derived from the patient's own tissues.

Current approaches to cell replacement therapy in Parkinson's disease (PD) are strongly focused on the dopamine system, with the view that restoring dopaminergic inputs in a localized and physiologic manner will provide superior benefits in terms of effect and longevity compared with oral medication. Experience using transplants of fetal tissue containing dopaminergic cell precursors has provided valuable proof that the approach is feasible, and that engrafted cells can survive and function over many years. However, multiple drawbacks and procedural complications are recognized in using fetal cells.

Recent strides in stem cell technology now make it possible to overcome some of the barriers associated with fetal tissue. The first generation of stem cell-derived dopaminergic neurons now in the pipeline is predicted to perform at least at an equivalent level to human fetal cells, but in a more robust and reproducible manner, providing a stable, expandable, and readily accessible cell source for transplantation. As such the therapy is expected to provide a better way of treating the dopamine responsive features of PD using a targeted, physiological delivery of dopamine to the striatum, but it is not a disease modifying treatment, nor a cure.

Many questions remain to be addressed. For example, PD pathology is not cell-autonomous, and the spread of pathology potentially affecting graft function is an oft-repeated although unsubstantiated objection to cell therapy. While current evidence supports absence of any major effect, it does raise the question of whether a combinatorial therapy comprising grafting and, for example, a biologic or small molecule to abrogate spread of alpha-synuclein pathology would be desirable.

In this article we have only discussed use of dopaminergic cells, whereas a stem cell source allows growth of any cell type. Other neural networks would be much more difficult to rebuild, but it is tempting to speculate that, for example, cholinergic neurons could be helpful in addressing cognitive function, or balance. There is a long road ahead in demonstrating how well stem cell-based reparative therapies will work, and much to understand about what, where, and how to deliver the cells, and to whom. But the massive strides in technology over recent years make it tempting to speculate that cell replacement may play an increasing role in alleviating at least the motor symptoms, if not others, in the decades to come.


Recent Papers on the Cellular Senescence Produced by Visceral Fat Tissue

Today, I thought I'd point out a couple of papers that touch on different aspects of the overlap between visceral fat tissue and senescent cells in aging. In the first paper, researchers show that the ability of visceral fat tissue to generate the markers of senescence is suppressed when the circulatory system of an old mouse is linked to a younger mouse. All of the ongoing, unresolved arguments over why this sort of modest rejuvenation occurs apply here; my money is still on it being dilution of harmful factors in an aged bloodstream. In the second paper, researchers link yet another aspect of dysfunction in the brain to the presence of senescent cells, in this case disorders such as anxiety and depression that are linked to fat tissue. The senescent cells can be used to explain that association with excess fat tissue.

Excess visceral fat tissue is harmful in many different ways, damaging the body and the brain. It is metabolically active, distorting the normal operation of cellular metabolism and tissue functions throughout the body. Further, it generates chronic inflammation via what appears to be quite a wide variety of mechanisms, from inappropriate cell signaling to DNA debris from dead fat cells. Short bursts of inflammation are a normal part of the response to injury and infection. When those mechanisms become stuck, however, activated without cease for the long term, then they become very damaging. Chronic inflammation accelerates the progression of all of the most common disabling and ultimately fatal age-related conditions. Being overweight speeds up that process.

As ever more of the research community becomes convinced (finally) that senescent cells are an important root cause of degenerative aging, more attention is being directed to all of the inflammatory conditions and states, searching for the senescent cells that no doubt cause a sizable fraction of that inflammation. Even in very old people, it is thought that there are only a small number of senescent cells present in tissues - perhaps a few percent of all cells at most. Yet these errant cells have a sizable detrimental effect, as the damage they do is mediated by the signal molecules that they generate, influencing the behavior of countless other cells near and far. Pro-inflammatory signals are one of the better understood consequences of cellular senescence, and the reason why these cells are a significant cause of inflammatory disease in old age.

Thus fat tissue doesn't have create many more senescent cells, in absolute numbers, in order to place a significant burden of damage and dysfunction on the rest of the body. Sadly, it does indeed create those cells. We can quite accurately say that being overweight results in an acceleration of aging, a consequence reflected in mortality rates, disease risk, and medical expenditure. The overweight and the obese have shorter, less healthy, more expensive lives, with all of those disadvantages scaling with the amount of excess visceral fat tissue, and the length of time it is carried. That isn't all down to senescent cells - there are plenty of other issues to consider in the harmful biochemistry of large amounts of fat tissue. I am sure that the development of senolytic therapies to destroy senescent cells will lead to a quantification of just how much of the damage done by being overweight is down to cellular senescence. Building therapies is the fastest way to obtain answers to this sort of question.

Adipose tissue senescence and inflammation in aging is reversed by the young milieu

Visceral adipose tissue (VAT) inflammation plays a central role in longevity and multiple age-related disorders. Cellular Senescence (SEN) is a fundamental aging mechanism that contributes to age-related chronic inflammation and organ dysfunction, including VAT. Recent studies using heterochronic parabiosis models strongly suggested that circulating factors in young plasma alter the aging phenotypes of old animals. Our study investigated if young plasma rescued SEN phenotypes in the VAT of aging mice.

With heterochronic parabiosis model using young (3 months) and old (18 months) mice, we found significant reduction in the levels pro-inflammatory cytokines and altered adipokine profile that are protective of SEN in the VAT of old mice. These data are indicative of protection from SEN of aging VAT by young blood circulation. Old parabionts also exhibited diminished expression of cyclin dependent kinase inhibitors (CDKi) genes p16 (Cdkn2a) and p21 (Cdkn1a/Cip1) in the VAT.

In addition, when exposed to young serum condition in an ex-vivo culture system, aging adipose tissue-derived stromovascular fraction cells (SVFs) produced significantly lower amounts of pro-inflammatory cytokines (Mcp-1 and IL-6) compared to old condition. Expressions of p16 and p21 genes were also diminished in the old SVFs under young serum condition. Finally, in 3T3 pre-adipocytes culture system; we found reduced pro-inflammatory cytokines (Mcp-1 and IL-6) and diminished expression of CDKi genes in the presence of young serum compared to old serum. In summary, current study demonstrates that young milieu is capable of protecting aging adipose tissue from SEN and thereby inflammation.

Obesity-Induced Cellular Senescence Drives Anxiety and Impairs Neurogenesis

Cellular senescence entails a stable cell-cycle arrest and a pro-inflammatory secretory phenotype, which contributes to aging and age-related diseases. Obesity is associated with increased senescent cell burden and neuropsychiatric disorders, including anxiety and depression. To investigate the role of senescence in obesity-related neuropsychiatric dysfunction, we used the INK-ATTAC mouse model, from which p16Ink4a-expressing senescent cells can be eliminated, and senolytic drugs dasatinib and quercetin.

We found that obesity results in the accumulation of senescent glial cells in proximity to the lateral ventricle, a region in which adult neurogenesis occurs. Furthermore, senescent glial cells exhibit excessive fat deposits, a phenotype we termed "accumulation of lipids in senescence." Clearing senescent cells from high fat-fed or leptin receptor-deficient obese mice restored neurogenesis and alleviated anxiety-related behavior. Our study provides proof-of-concept evidence that senescent cells are major contributors to obesity-induced anxiety and that senolytics are a potential new therapeutic avenue for treating neuropsychiatric disorders.

Interfering in the Interaction between Amyloid-β and Prion Protein as a Treatment for Alzheimer's Disease

The damage of Alzheimer's disease mediated by aggregation of amyloid-β and tau protein deposits isn't so much due to the aggregates, but rather the surrounding halo of complex interactions and related proteins. One of those thought to be important is between oligomeric amyloid-β and cellular prion protein, the latter of which is also of note in transmissible spongiform encephalopathy. Researchers here sought to interfere in this interaction, and achieved interesting results, at least in a mouse model of Alzheimer's disease. The usual caveats apply, in that Alzheimer's mouse models are highly artificial constructs, since nothing resembling Alzheimer's naturally occurs in that species. The relevance of these varied models to the real condition is very dependent on the details of the model and the details of the treatment - there is plenty of room for later failure even given good results in mice.

Researchers have identified a drinkable cocktail of designer molecules that interferes with a crucial first step of Alzheimer's and even restores memories in mice. The binding of amyloid beta peptides to prion proteins triggers a cascade of devasting events in the progression of Alzheimer's - accumulation of plaques, a destructive immune system response, and damage to synapses.

Researchers screened tens of thousands of compounds looking for molecules that might interfere with the damaging prion protein interaction with amyloid beta. They found that an old antibiotic looked like a promising candidate but was only active after decomposing to form a polymer. Related small polymers retained the benefit and also managed to pass through the blood-brain barrier. They then dissolved the optimized polymeric compound and fed it to mice engineered to have a condition that mimics Alzheimer's. They found that synapses in the brains were repaired and mice recovered lost memory.

A collaborating team reported a positive response when they delivered the same cocktail to cells modeled to have Creutzfeldt-Jakob Disease, a devasting neurological condition caused by infection with misfolded prion protein. The next step is to verify the compounds aren't toxic in preparation for translation to clinical trials for Alzheimer's disease.


Life Extension Advocacy Foundation 2018 Retrospective

The Life Extension Advocacy Foundation (LEAF) staff members have grown their efforts considerably over the past year, including the launch of a yearly conference series and a network of angel investors focused on startup companies engaged with the aging process. The LEAF blog should probably be on your reading list. Insofar as a position on aging goes, the Life Extension Advocacy Foundation folk appear more guided by the Hallmarks of Aging view than the SENS view, but there is a significant overlap, and many of their past fundraising efforts have directly supported the SENS Research Foundation. The more fellow travelers the better; there is certainly the need for a great deal more patient advocacy for the treatment of aging than presently takes place.

In May, we officially announced our first conference held in New York City, Ending Age-Related Diseases: Investment Prospects and Advances in Research, which would then be held in July. The Longevity Investor Network, LEAF's own initiative to foster a flourishing rejuvenation biotech ecosystem, was also launched in May under the lead of Javier Noris; speaking of investments, at around the same time, a generous anonymous donor decided to invest both money and trust in us by becoming a Lycium-level Lifespan Hero and pledging $2,000 a month. We'd like to express our most sincere gratitude to this donor as well as to all our Heroes for all they do for us.

Although organizing the upcoming New York City conference took a great deal of effort and time, we still got quite a few interviews out in July. This was not all, as one of our most important projects was also launched in July - the Rejuvenation Roadmap, a curated database of hallmark-categorized, work-in-progress rejuvenation therapies, the companies developing them, and their current state of development. The Roadmap is our way of answering the question, "How far are we from defeating aging?", and it has grown quite a bit since it was first announced; hopefully, it'll grow much more in 2019!

In August, Michael Kope from SENS Research Foundation joined our newly formed Industry Advisory Board (IAB) and will provide business guidance and advice to LEAF as our organization continues to grow and develop. Michael and the other members of the IAB will be a great asset in helping us to achieve our goals. The AgeMeter biomarker scan, which was successfully crowdfunded in late 2017 on, became available for purchase on its own website near the end of August. We also should have an update regarding data access for project backers early in the new year.

In mid-September, we launched our most recent crowdfunding campaign on, the NAD+ Mouse Project which was aimed at studying whether the administration of the NAD+ precursor nicotinamide (NMN), in both normal and accelerated-aging mice, confers the rejuvenative benefits that were first observed in previous studies.

As we look back on the year, we have published over 400 articles, with a corresponding 10-fold increase in traffic from our readers over the previous year. We have also hosted 10 pitch meetings to help young rejuvenation startups connect with investors as part of the Longevity Investor Network, a project aimed at bringing together researchers and investment funding. We hope that 2019 will be at least as intense as its predecessor, and given the all-around progress in the field and the growing interest in it, we're sure that we can look forward to it.


Tau and Amyloid-β Synergize to Impair Neural Activity in Alzheimer's Disease

The mainstream of the Alzheimer's research community remains primarily interested in clearing deposits of amyloid-β from the aging brain. That said, there is a growing interest in tackling tau aggregation as well, particularly given the long years of failure to achieve meaningful results through clinical trials of immunotherapies that target amyloid-β. The current consensus on the development of the disease is that increased amyloid-β, leading to solid deposits of amyloid in and between cells, is an early phenomenon, and may in and of itself do little more than create mild cognitive impairment. However, amyloid-β aggregation sets the stage for the later production of neurofibrillary tangles, consisting of an altered form of tau protein, and these are far more harmful to brain function.

Both tau and amyloid-β protein aggregates are biochemically complex, with a surrounding halo of many varieties of harmful molecule. It is the halo rather than the deposits that do the damage to brain cells and their function, or so present thinking goes. Further, more recent research suggests that while tau is the more harmful of the two, tau synergizes with amyloid-β to causes greater damage than it would on its own.

This view of the condition may explain why attempting to intervene late in the process with anti-amyloid therapies fails to produce sizable benefits, but nonetheless does appear to help to some degree, particularly in animal models. So perhaps amyloid-β clearance as an approach is best harnessed for prevention or slowing of early development of the condition. Still, that leaves the challenge of treating later stages of the condition for present patients, and thus a growing number of researchers are working on ways to remove tau aggregates. Many of those scientists advocate for the development of therapies that clear both tau and amyloid-β at the same time, a strategy that seems very reasonable given the evidence to date.

Tau protein suppresses neural activity in mouse models of Alzheimer's disease

A new study sheds light on how the hallmarks of Alzheimer's disease - amyloid-beta (A-beta) plaques and neurofibrillary tangles containing the protein tau - produce their damaging effects in the brain. The findings suggest that strategies directed against both pathologic proteins, rather than one or the other, might be promising therapeutic options. "Our current study reinforces growing evidence suggesting that A-beta and tau work together to impair brain function and that, for certain aspects of that impairment, tau predominates. We are intrigued to learn how they are interacting at a molecular level, in order to find ways of blocking that synergy."

Studies with two mouse models that overexpress different forms of tau found, for the first time, that elevated levels of the protein were associated with a significant reduction in neural activity whether or not tau had aggregated into tangles. Experiments with a novel mouse model that overexpresses both A-beta and tau found that, in the presence of both pathological proteins, A-beta-associated hyperactivity was abolished and tau's neuronal silencing effect predominated. The findings were duplicated in mice regardless of their age, including animals too young to exhibit the loss of neurons typically seen in animals that only overexpress tau.

The authors note that their findings could help explain why clinical trials of A-beta-blocking therapies have had difficulty improving symptoms of patients with Alzheimer's disease. "One implication of our work is that approaches combining anti-A-beta and anti-tau therapies might be more effective than either alone, at least from the perspective of neural activation. Finding that tau and A-beta work in a synergistic fashion opens the doors to new research into understanding exactly how that interaction works."

Tau impairs neural circuits, dominating amyloid-β effects, in Alzheimer models in vivo

The coexistence of amyloid-β (Aβ) plaques and tau neurofibrillary tangles in the neocortex is linked to neural system failure and cognitive decline in Alzheimer's disease. However, the underlying neuronal mechanisms are unknown. By employing in vivo two-photon Ca2+ imaging of layer 2/layer 3 cortical neurons in mice expressing human Aβ and tau, we reveal a dramatic tau-dependent suppression of activity and silencing of many neurons, which dominates over Aβ-dependent neuronal hyperactivity.

We show that neurofibrillary tangles are neither sufficient nor required for the silencing, which instead is dependent on soluble tau. Surprisingly, although rapidly effective in tau mice, suppression of tau gene expression was much less effective in rescuing neuronal impairments in mice containing both Aβ and tau. Together, our results reveal how Aβ and tau synergize to impair the functional integrity of neural circuits in vivo and suggest a possible cellular explanation contributing to disappointing results from anti-Aβ therapeutic trials.

Considering Mesenchymal Stem Cell Therapy for Atherosclerosis

Mesenchymal stem cell (MSC) therapies as presently practiced, even given considerable differences in what exactly is meant by "mesenchymal stem cell", fairly reliably reduce the chronic inflammation of aging for an extended period of time. They are much less reliable at inducing regeneration of tissues, and where that does occur it probably results from dampened inflammation. One of the many detrimental consequences of the always-on inflammatory signaling that arises with age is a disruption of regenerative capacity. Given the ability of MSC transplantation to suppress inflammation, it is possible that this could be at least marginally useful as a therapy for any age-related condition in which inflammation is an important component.

Here, researchers consider MSC therapies as a way to slow down atherosclerosis, as inflammation strongly influences the pace at which this condition progresses. They also suggest that atherosclerosis is linked to the age-related failure of native MSCs to regulate inflammation. There are several possible reasons for this. Firstly, inflammation goes hand in hand with oxidative stress, the presence of greater levels of oxidizing molecules. This means it also leads to more of the oxidized lipids that cause macrophages attempting to clean up atherosclerotic lesions to become harmful foam cells that instead accelerate growth of the lesions. Secondly, macrophage behavior is influenced by the state of inflammatory signaling. Macrophages that are normally helpful can be coerced into amplifying inflammation, switching to an aggressive inflammatory mode rather than assisting in repair of lesions.

Atherosclerosis, a chronic inflammatory disease of the wall of large- and medium-sized arteries, is the most common pathological process leading to cardiovascular disease (CVD). The hallmark lesion in atherosclerosis is the atherosclerotic plaque. An alternative strategy to target inflammatory pathways for CVD therapy could be enhancing physiological mechanisms that antagonize inflammation. Key cellular targets for this approach are multipotent mesenchymal stromal cells (MSC). MSC are non-hematopoietic clonogenic perivascular multipotent stromal cells that can be induced to differentiate in vitro into osteoblasts, chrondrocytes, or adipocytes. MSC function as pivotal regulators of inflammation by modulating innate and adaptive immune cells. This does not require long-term engraftment of MSC in target tissues. The crosstalk between MSC and immune cells is mainly mediated by secreted bioactive molecules.

Limited data are available for MSC from patients with atherosclerosis. Specifically, the contribution of MSC dysfunction to the persistence of chronic inflammation and plaque progression are ill-defined. This relates in part to the lack of specific markers that can identify MSC in vivo in human arteries. We have overcome this obstacle by using an alternative approach. Thus, we have characterized adipose derived MSC from atherosclerotic patients (i.e. subjects undergoing coronary artery bypass graft surgery) and compared their function with MSC from non-atherosclerotic patients. Immunopotency (i.e. the MSC capacity to suppress the proliferation of allogenic activated T-cells) was used as the main readout of MSC function. Initial findings confirmed that atherosclerotic-MSC have impaired immunomodulatory capacity and a pro-inflammatory secretome, both contribute to the state of chronic low-grade inflammation that promotes atherosclerosis progression. Moreover, we demonstrated that MSC immunopotency can indeed be enhanced by modulating inflammatory components of the MSC secretome.

There are multiple potential implications of these data. First, the therapeutic effectiveness of atherosclerotic-MSC is likely compromised when compared to their non-atherosclerotic counterparts. Accordingly, only non-atherosclerotic MSC should be used in clinical trials. Second, the ability to modulate the redox state of MSC is a possible strategy to enhance the therapeutic efficacy of autologous atherosclerotic-MSCs. Third, increasing age is an established independent risk factor for the development of atherosclerosis. Notably, mitochondrial dysfunction is not only associated with aging, but also with premature or accelerated atherosclerosis. Our study was not designed to address the contribution of MSC dysfunction to atherosclerosis onset or progression. However, our results strongly suggest this link, and we have set the stage to test this hypothesis in the future.


The Uncertain Details of Retinal Aging

This open access paper examines what is known of the aging of the retina, and notes the difficulties inherent in relating any of those changes to specific declines in vision. The research community has an increasingly detailed view of exactly what differentiates an old retina from a young retina, structurally, chemically, and in the changing behavior of the various types of cell that make up retinal tissue. It is a challenge to relate data obtained in laboratory animals to loss of specific aspects of visual function, however, particularly the more subtle ones. One can't ask mice and rats to sit through the same test procedures as humans undergo, and obtain useful feedback via that approach.

Visual aging is linked to a decline in functional activity causing lower visual acuity, lower contrast sensitivity and impaired dark adaptation. However, although it has been reported that the age-related visual impairment is mainly due to a neuronal malfunction together with cell loss, the specific reasons of aging are still uncertain. How, and at what level, are the diverse neuronal populations affected? And how much are other retinal players involved?

By characterizing retinal aging in experimental animals (pigmented and albino rats) under controlled and healthy conditions, we found that the retinal function, as measured with full field electroretinograms, decreased ~50% at 22-months compared with 2-month-old rats. Whether neuronal malfunction or cell loss is mainly responsible for this reduced functionality is still an open question, even though structural changes in the optical components may contribute to this reduction. Interestingly, several studies suggest cell loss based on the retinal thinning that occurs with aging. However, although when we measured the retinal layers in vivo we observed a decrease in thickness ~14%, we also saw that the constant retinal growth was responsible for the retinal thinning, since volumetric and quantification analyses indicated that the thinning did not involve neuronal loss.

The retina is a highly organized and specialized tissue. The light-sensitive photoreceptors are essential for an effective signal transduction and to initiate the efficient transmission of impulses through the retina. They are vulnerable to light-induced damage and many publications have shown the degeneration of outer segments during aging. The central retina probably receives greater light exposure triggering different metabolic requirements that increases metabolic stress. In fact, a deficiency in DNA repair enzymes, damage induced by excitatory amino acids, specific age-related metabolic changes, a general decline in autophagy activity, and reduced energy production by mitochondrial metabolism collectively result in oxidative stress that may affect photoreceptor functionality. All that in addition to lipofuscin accumulation, morphological alterations and damage in the retinal pigmented epithelium accompanied by a para-inflammatory response are the signature signs of aging in the retina.

To preserve visual function, the eyes and brain require precisely tuned machinery. Any of the above-mentioned changes related to aging, including synapse remodelling or neuronal loss in response to age may contribute or play a crucial role in the continuous and irreversible decline in vision. Importantly, age may end causing a partial or complete distorted image formation, more so in a timeframe where our lifespan is increasing. So, could this retinal dysfunction be prevented or restored?


An Initial Assessment of the Phenotypic Age Metric

Today's open access paper adds to the growing number of attempts to construct a useful biomarker of aging from a combination of simple, available metrics. The Phenotypic Age measure described here uses a few fairly standard measures from blood samples as a basis, which might lead us to suspect it is heavily biased towards measuring immune system aging. Insofar as immune system function is important to overall health, and immune system function declines with age, then so far so good. The challenge with all of these potential biomarkers is less how well they do in the world of natural aging, to predict who will have a higher mortality in the years ahead, and more how they respond to specific classes of rejuvenation therapy.

The primary rationale for spending any time on the development of a biomarker of aging is to produce a fast, low-cost way of assessing the results of an alleged rejuvenation treatment. At present only life span studies can reliably determine how well such a treatment performs. Such studies are expensive and slow in mice, and out of the question in humans. This is a major impediment to progress. What is needed is an approach that enables researchers to treat older animals and people, and then a month later run a quick test to assess the results. That would speed up development in this field immensely. The work carried out in recent years on epigenetic clocks suggests that a robust biomarker of aging is a feasible goal.

The most important question remains to be answered, however: how will all of the various potential biomarkers of aging react to specific classes of rejuvenation therapy, such as senolytic drugs to clear senescent cells? A biomarker heavily based on immune cell characteristics may provide results that are of little relevance to changes taking place in the tissues of important inner organs, and vice versa. Until these interactions are well quantified by researchers, the biomarkers are not terribly useful - the output will provide a number, but what does that number really mean? Building biomarkers and building rejuvenation therapies will, at least at the outset, have to proceed in parallel, with the two sides incrementally validating one another.

A new aging measure captures morbidity and mortality risk across diverse subpopulations from NHANES IV: A cohort study

One method for determining whether a person appears younger or older than expected on a biological or physiological level is to compare observable characteristics, reflecting functioning or state, to the characteristics observed in the general population for a given chronological age. A number of aging measures have been proposed using molecular variables, the most prominent being epigenetic clocks (expressed as DNA methylation age, in units of years) and leukocyte telomere length. We and others have previously shown that while these measures are phenomenal age predictors - especially DNA methylation age - their associations with aging outcomes above and beyond what is explained by chronological age is weak to moderate. Conversely, aging measures based on clinically observable data, or phenotypes, tend to be more robust predictors of aging outcomes.

The differences in prediction between these two types of measures could reflect that molecular measures may only capture one or a small number of changes involved in the multifactorial aging process, while on the other hand, clinical measures may represent the manifestations of multiple hallmarks of aging occurring at the cellular and intracellular levels. While composite scores based on traditional clinical chemistry measures are not mechanistic, their better performance and relative affordability and practicality compared to current molecular measures may make them more suitable for evaluating the effects of aging interventions on an organismal scale, and/or identifying groups at higher risk of death and disease.

Among the existing clinical measures, the majority were generated based on associations between composite variables and chronological age - with no integration of information on how the variables influence morbidity and mortality. Given that individuals vary in their rate of aging, chronological time is an imperfect proxy for building an aging measure. Recently, we developed a new metric, Phenotypic Age (in units of years), that incorporates composite clinical chemistry biomarkers based on parametrization from a Gompertz mortality model. Rather than predicting chronological age - as previous measures have done - this measure is optimized to differentiate mortality risk among persons of the same chronological age, using data from a variety of multi-system clinical chemistry biomarkers.

In general, a person's Phenotypic Age signifies the age within the general population that corresponds with that person's mortality risk. For example, two individuals may be 50 years old chronologically, but one may have a Phenotypic Age of 55 years, indicating that he/she has the average mortality risk of someone who is 55 years old chronologically, whereas the other may have a Phenotypic Age of 45 years, indicating that he/she has the average mortality risk of someone who is 45 years old chronologically.

All analyses were conducted using NHANES IV (1999-2010, an independent sample from that originally used to develop the measure). Our analytic sample consisted of 11,432 adults aged 20-84 years and 185 oldest-old adults top-coded at age 85 years. We observed a total of 1,012 deaths, ascertained over 12.6 years of follow-up. Proportional hazard models and receiver operating characteristic curves were used to evaluate all-cause and cause-specific mortality predictions. Overall, participants with more diseases had older Phenotypic Age. For instance, among young adults, those with 1 disease were 0.2 years older phenotypically than disease-free persons, and those with 2 or 3 diseases were about 0.6 years older phenotypically.

After adjusting for chronological age and sex, Phenotypic Age was significantly associated with all-cause mortality and cause-specific mortality (with the exception of cerebrovascular disease mortality). Results for all-cause mortality were robust to stratifications by age, race/ethnicity, education, disease count, and health behaviors. Further, Phenotypic Age was associated with mortality among seemingly healthy participants - defined as those who reported being disease-free and who had normal BMI - as well as among oldest-old adults, even after adjustment for disease prevalence.

Towards a Biomarker of Aging Based on the Gut Microbiome

A low-cost, low-effort way to accurately assess biological age, meaning the burden of molecular damage and the countless harmful cellular reactions to that damage, would greatly speed development of rejuvenation therapies. Ideally researchers would be able to apply a therapy and then within a month obtain a measure of how greatly it affects aging. At present the only reliable way to fully assess means of slowing or reversing aging is to run life span studies, which are slow and expensive in mice, and simply not feasible in humans.

Thus a fair amount of effort is presently devoted to the development of biomarkers and combinations of biomarkers that might one day serve this purpose. In this preprint paper, researchers outline their work on the use of the gut microbiome as a basis for a biomarker of aging. It is known that characteristic changes occur in the microbiome with age, many of them detrimental and associated with the development of age-related disease, but there is a high degree of variability between individuals and study populations. Thus these results will certainly need a much broader replication as a part of any further development.

Although infant microbiome succession is well studied and can be used to assess the risks of various health conditions, its transition to adult microbiome is less understood. More so, composition variability attributed to geographic location, medical history, diet, and other factors make it hard to analyze adult microbiomes as effectively as those of infants. Age-related studies of human microbiome have failed to produce a straightforward theory of gut flora aging.

Some studies indicate decreasing biodiversity in the elderly gut. However, that is not the case for all data sets, and elderly healthy people may have microbiomes as diverse as the younger population. Other findings include changes in specific taxa abundance in aging microbiota. Such bacterial genera as Bacteroides, Bifidobacterium, Blautia, Lactobacilli, Ruminococcus have been shown to decrease in the elderly, while Clostridium, Escherichia, Streptococci, Enterobacteria increase. However, these patterns are not strictly established as results vary greatly across different studies. This may be attributed to different methodologies as well as unbalanced data sets that may contain people of different lifestyles.

Despite these complications, the consensus is that the elderly gut has lower counts of short chain fatty acid (SCFA) producers such as Roseburia and Faecalibacterium and an increased number of aerotolerant and pathogenic bacteria. Such shifts can lead to dysbiosis, which in turn contributes to the onset of multiple age-related diseases.

The standard way of separating the gut microbiome into three chronological states - child, adult, and elderly microbiomes - lack a clear set of rules. Among them, adult microbiome remains the greatest mystery. It has no established succession stages, as in newborns, and does not normally reflect gradient detrimental processes typical for an old organism. This poses a question whether normal adult microbiome progresses at all or it is in a state of stasis. Considering the aging process is gradual and involves accumulation of damage and other deleterious changes (as also indicated by a number of biomarkers such as DNA methylation clocks), it is logical to suppose that gut microbiome succession is also gradual. However, attempts to use microbiome-derived features to predict chronological age have been inconclusive.

Here, we developed a method of predicting the biological age of the host based on the microbiological profiles of gut microbiota using a curated dataset of 1,165 healthy individuals. Our predictive model, a human microbiome clock, has an architecture of a deep neural network and achieves the accuracy of 3.94 years mean absolute error in cross-validation. The performance of the deep microbiome clock was also evaluated on several additional populations. This approach has allowed us to define two lists of 95 intestinal biomarkers of human aging. We further show that this list can be reduced to 39 taxa that convey the most information on their host's aging. Overall, we show that (a) microbiological profiles can be used to predict human age; and (b) microbial features selected by models are age-related.


NAD+ and Cellular Senescence in Intestinal Tissue Organoids

Organoids are a useful intermediary step between cell cultures and animal studies, allowing for investigations to be carried out in a structured tissue that is much closer to the real thing than cells in a petri dish. Researchers here use intestinal tissue organoids derived from old mice to show that raised levels of NAD+ suppress markers of cellular senescence - which most likely indicates suppression of activity rather than outright destruction of senescent cells to any great degree, given what we know of how calorie restriction affects NAD+ and senescent cells.

NAD+ levels are connected to mitochondrial function, and fall with age. A growing industry is now selling various means to raise NAD+ in order to improve mitochondrial function and thus tissue function. Some of these appear to be beneficial in early trials, while others seem ineffective. Past research has connected NAD+ with cellular senescence, or mitochondrial function with cellular senescence, but rigorous data on the size of the effect has yet to be produced. This narrow slice of the benefits of increased mitochondrial function is unlikely to compare favorably with the effects of senolytics, the outright destruction of senescent cells in large numbers.

Here we have demonstrated that the important stem cell marker Lgr5 was epigenetically silenced by trimethylation of histone H3K27, inducing suppression of Wnt signaling and a decrease of cell proliferation in intestinal epithelial organoids derived from aged mice. In these organoids, we also observed accumulation of SA-β-gal, a decrease in the expression of DNA methyltransferases and an increase in the expression of p21, indications of cellular senescence.

Epigenetic silencing of Lgr5 and induction of senescence occurs in aged intestinal organoids. The stem cell marker Lgr5 was substantially expressed in young intestinal epithelial organoids, whereas it was faintly expressed in aged intestinal organoids. Examination of DNA methylation levels around the Lgr5 promoter region revealed no significant difference in DNA methylation between young and aged intestinal organoids. Since Lgr5 is an activator of the Wnt signaling pathway, epigenetic silencing of Lgr5 results in suppression of Wnt signaling, which may lead to decreased cell proliferation and activation of senescence-associated genes such as p21 due to suppression of DNA methylation.

Recently, calorie restriction experiments have highlighted Sirt1 as a possible longevity gene. Sirt1 has histone acetyl transferase activity and its expression is regulated by the concentration of NAD+. Aging leads to a reduction of NAD+ in the body, and it has been reported that supplementation of NAD+ induces longevity and stem cell activation. Here, intestinal epithelial organoids derived from aged mice grew larger, forming crypt-like structures after treatment with NMN, a key NAD+ intermediate. The aged intestinal epithelial organoids treated with NMN showed an increase of proliferative activity, activation of Lgr5 and Sirt1, and suppression of p21 and p16, suggesting that treatment with NMN was able to ameliorate senescence-related changes in intestinal epithelia and could have potential application as an anti-aging intervention.


Ambrosia Health and the Downsides of Developing Marginal Therapies

One of the many good reasons to be guided by the SENS approach to aging, meaning a focus on repairing molecular damage as close to the causes of aging as possible, is that it has a greater likelihood of resulting in a viable therapy. Benefits should turn out to be sizable, broadly applicable to many age-related conditions, and reliable. The present best example of the type is provided by senolytic therapies that clear senescent cells. The more prevalent and popular strategy of tinkering with metabolism or adjusting the late-stage, dysfunctional disease state, throwing signals into the mix to override cellular reactions to damage, or upregulate stress responses, and while hoping for the best, has a high failure rate in larger human trials. With few exceptions, benefits tend to be unreliable, narrowly applicable to just a handful of conditions, and small.

Unfortunately, once development has reached the stage of a funded company focused on developing a particular therapy, it is hard for anyone involved to back down and admit failure to achieve good results. A few companies, Ambrosia and Alkhahest, are currently in this position when it comes to the use of blood and plasma transfusions to try to recreate the benefits observed in parabiosis studies. In these animal studies, the circulatory systems of old and young mice are linked; the young mice suffer accelerated measures of aging and they old mice gain some reversal of measures of aging. Unfortunately, research completed after these companies were established, and then the data generated by the companies themselves, shows that there is nothing here of interest. If there is an effect resulting from transfusion, it is small and unreliable. For one, transfusion is a terrible way to try to recreate the effects of a complete joining of circulatory systems, and secondly the evidence now strongly indicates that benefits in the old mice in parabiosis studies are more a matter of dilution of harmful factors in old blood rather than the delivery of beneficial factors in young blood.

The media are sharks and will cheerfully build a narrow pedestal for a company and its founders one day, uncritically accepting all company statements as fact without challenge, and then turn on a dime to knock all it down the moment that the data fails to live up to unrealistic expectations. They will be unkind about failure, regardless of how deserving the people involved actually are; they will mix together all possible reasonable and unreasonable accusations while constructing their narrative, as illustrated in today's article below. This is another thing to bear in mind when considering what sort of medical biotechnology to pursue, and how to pitch it at the outset.

The article here assembles a grab-bag of complaints about Ambrosia, some of which are valid and useful, and some of which are quite pernicious, such as the leading presentation of the death of an aged trial participant, or the way the authors played the public opinion game with blood banks. Most of the technical complaints about lack of effect for the therapy could just as well be leveled at Alkahest, but Ambrosia is an easier target given their non-traditional approach to trials and present diminished position. For my part, I see nothing wrong with patient paid trials that are responsibly conducted. It allows for tests of potential therapies that might otherwise never happen. There is an unseemly hostility to this approach to trials, sad to say, both in the research community and in the media. Objections on that front when a company fails to produce good results are irrelevant and unhelpful. On the other hand, calling out the founders of companies that continue with a failed program because no-one has the moral courage to admit failure and call a halt is a good thing, and it is a pity that it isn't done in most such cases.

Jesse Karmazin, the founder of the startup Ambrosia, had a pitch journalists couldn't resist: For a fee, he could help his clients combat aging and its related ills with infusions of blood plasma from the young. Teen donors, vampiric undertones, a serious-sounding study, an $8,000-per-person price tag and rumors that venture capitalist Peter Thiel might be interested earned Ambrosia more than 100 press mentions in just two years.

But despite declaring the study a success and announcing plans this week to accept new clients, Karmazin never showed any proof that the transfusions actually helped people. In the media, he touted impressive results, but almost a year after his study officially concluded in January 2018, he hasn't released them. Scientists have criticized the study as flawed and the procedure as medically unnecessary and not without risk; in rare cases, transfusion complications can be fatal. One of the doctors Karmazin hired had previously been disciplined by a state medical board for unprofessional conduct.

Karmazin himself cannot legally practice medicine in any state; he is explicitly prohibited from practicing in Massachusetts by authorities. Ambrosia's president and chief operating officer quietly left the company in late December, leaving Karmazin as the sole employee. And the only patient who spoke publicly about Ambrosia's transfusions - treatments he hoped would help him live healthier into old age - died at 65 after going into cardiac arrest.

We found that at least some of Karmazin's young plasma came from a nonprofit blood bank in Texas that recruited teenage donors for "saving lives," but noted on a consent form that their blood components could also be used for "any other medical purpose." The bank abruptly decided to stop selling young plasma after we reached out, according to an employee email.

Ambrosia, which declined to comment on whether the company has any investors, is only one of many firms investigating how to help people feel younger for longer. But Ambrosia's ability to attract paying clients and years of positive press coverage - without providing scientific data to back up its claims - shows just how easy it can be for promises to outpace the research when Silicon Valley gold-chasing mixes with Americans' fear of death.


An Incomplete Survey of Novel Approaches to Alzheimer's Disease

This open access paper is illustrative of a dogmatic mainstream of Alzheimer's disease research in which treatments must be immunotherapy approaches to clearance of amyloid-β or tau, or lifestyle changes and other means of management of risk factors such as blood pressure. Little else is acceptable. Yet many other lines of investigation do exist, such as drainage or filtration of cerebrospinal fluid, or tageting viral causes of amyloid-β accumulation, and some have progressed as far as development in biotech startups. They are nowhere to be found in this review paper.

Alzheimer's disease (AD), the most prevalent neurodegenerative disease of aging, affects one in eight older Americans. Nearly all drug treatments tested for AD today have failed to show any efficacy. There is a great need for therapies to prevent and/or slow the progression of AD. The major challenge in AD drug development is lack of clarity about the mechanisms underlying AD pathogenesis and pathophysiology. Several studies support the notion that AD is a multifactorial disease.

While there is abundant evidence that amyloid plays a role in AD pathogenesis, other mechanisms have been implicated in AD such as neurofibrillary tangle formation and spread, dysregulated protein degradation pathways, neuroinflammation, and loss of support by neurotrophic factors. Therefore, current paradigms of AD drug design have been shifted from single target approach (primarily amyloid-centric) to developing drugs targeted at multiple disease aspects, and from treating AD at later stages of disease progression to focusing on preventive strategies at early stages of disease development.

Here we focus on current AD therapeutic strategies which comprise of mechanism-based approaches including amyloid-beta (Aβ) clearance, tau protein deposits, apolipoprotein-E (ApoE) function, neuroprotection and neuroinflammation, as well as non-mechanism based approaches including symptomatic cognitive stimulation, AD prevention, lifestyle modifications, and risk factor management including non-pharmacological interventions.


Giant Mole-Rats Exhibit Greater Gene Expression Stability with Aging than Rats

A number of African mole-rat species live significantly longer than similar-sized rodents, and show very little age-related decline until very late life. Where examined in detail, their biochemistry is an odd mix. In some respects they exhibit the usual signs of damage and dysfunction associated with mammalian aging, such as raised oxidative stress and the presence of senescent cells, but don't appear all that affected by it. Elsewhere they exhibit clearly superior mechanisms, such as improved protein quality control, a layered set of anti-cancer mechanisms that provide near immunity to cancer, and - the topic of this paper - a well preserved pattern of gene expression. This latter case may be something of a tautology: dysregulation of gene expression, or changes in gene expression that are reactions to underlying damage, are a downstream consequence of the causes of aging. When an organism ages more slowly, or exhibits only a lesser degree of aging until very late life, then one would naturally expect gene expression patterns to remain more stable over time.

Compared to short-lived mammals, long-lived mammals have repeatedly been shown to exhibit fewer age-associated changes in numerous physiological parameters related to the functional decline during aging. Recent RNA-seq studies have suggested that much of the remarkable lifespan diversity among mammals is based on interspecies differences in gene expression. However, those studies focused on identifying particular genes and pathways that are differentially expressed between species with divergent longevities. Whether short-lived and long-lived species differ at the transcript level with respect to their amount of differentially expressed genes (DEGs) during aging (hereinafter referred to as "gene expression stability") has, to the best of our knowledge, not been explored yet.

Here, we examined age associated transcriptome changes in two similarly sized rodent species with different longevities: the laboratory rat (Rattus norvegicus), which has a maximum lifespan of 3.8 years, and the giant mole-rat (Fukomys mechowii), which has a maximum lifespan of more than 20 years. In giant mole-rats, longevity is significantly correlated with the reproductive status. Breeding animals outlive non-breeders by far. In the current study, we examined only non-breeding males. Male non-breeding giant mole-rats have a maximum lifespan of approximately 10 years and an average lifespan of approximately 6 years, still clearly exceeding the life expectancy of the laboratory rat.

For both species, we performed RNA-seq on tissue samples from five organs (blood, heart, kidney, liver, and skin; hereinafter called simply tissues) of young and elderly adults. The tissues were collected from young and elderly cohorts of laboratory rats (0.5 and 2.0 years) and giant mole-rats (young: approximately 1.5 years at average; elderly: approximately 6.8 years at average). For each species, we determined DEGs between the two respective time points and searched for enriched functional categories.

Our findings show that giant mole-rats exhibit higher gene expression stability during aging than rats. Although well-known aging signatures were detected in all tissue types of rats, they were found in only one tissue type of giant mole-rats. Furthermore, many differentially expressed genes that were found in both species were regulated in opposite directions during aging. This suggests that expression changes which cause aging in short-lived species are counteracted in long-lived species. Taken together, we conclude that expression stability in giant mole rats (and potentially in African mole-rats in general) may be one key factor for their long and healthy life.