Methionine Metabolism and the Pace of Aging

The prevailing wisdom in the research community is that a reduced level of the essential amino acid methionine is the primary trigger for the sweeping changes to metabolism that take place due to the practice of calorie restriction. Essential amino acids are not manufactured in the body, and thus must be obtained through the diet. The changes provoked by a reduced calorie intake lead to a slowing of aging and increased healthy life span and overall life span, largely mediated via an increase in the cellular maintenance processes of autophagy. Many other processes are involved as well, however, each adding their own small contribution, and animal studies suggest that reduced levels of other essential amino acids also have their own, lesser triggers that contribute to the whole.

That the response to calorie restriction does change just about everything in cellular metabolism makes it a challenging research topic, though the usual approaches have worked well: disable specific proteins one by one and see what happens. There is a lot of ground to cover and only so many researchers and so much funding to cover it with. The modern phase of the investigation of calorie restriction has been running in earnest for more than 25 years, but a complete understanding of calorie restriction will likely only slightly predate a complete understanding of cellular metabolism - a goal that is in no way near term.

Comparatively recent genomics, transcriptomics, and proteomics tools have added a great deal of data to the study of metabolism, and thus a great deal more work to the existing task list leading to the aforementioned complete understanding. Transcriptomics and other approaches to measuring gene expression patterns show that calorie restriction, intermittent fasting (with and without consequent calorie restriction), methionine restriction, and restriction of other specific nutrients (one by one), are all somewhat different. Yet the experiments showing that disabled autophagy prevents extension of life via calorie restriction suggest that it all converges at the same place.

While mapping the calorie restriction response and searching for calorie restriction mimetic drugs has made up the lion's share of translational gerontology to date, it is a sad truth that this class of intervention, meaning the upregulation of stress responses such as autophagy, works a great deal better in short-lived species such as mice than it does in long-lived species such as humans. Mice live 40% longer when calorie restricted, and humans most certainly don't. So while the long term health benefits of calorie restriction are meaningful, when compared with the little that modern medicine has been able to do to maintain the health of basically healthy people, they are not meaningful enough to merit major research funding, given the far better options on the table, those outlined in the SENS rejuvenation research programs.

Methionine metabolism and methyltransferases in the regulation of aging and lifespan extension across species

Methionine restriction (MetR) extends lifespan across different species and exerts beneficial effects on metabolic health and inflammatory responses. In contrast, certain cancer cells exhibit methionine auxotrophy that can be exploited for therapeutic treatment, as decreasing dietary methionine selectively suppresses tumor growth. Thus, MetR represents an intervention that can extend lifespan with a complementary effect of delaying tumor growth.

Beyond its function in protein synthesis, methionine feeds into complex metabolic pathways including the methionine cycle, the transsulfuration pathway, and polyamine biosynthesis. Manipulation of each of these branches extends lifespan; however, the interplay between MetR and these branches during regulation of lifespan is not well understood. In addition, a potential mechanism linking the activity of methionine metabolism and lifespan is regulation of production of the methyl donor S-adenosylmethionine, which, after transferring its methyl group, is converted to S-adenosylhomocysteine. Methylation regulates a wide range of processes, including those thought to be responsible for lifespan extension by MetR.

Although the exact mechanisms of lifespan extension by MetR or methionine metabolism reprogramming are unknown, it may act via reducing the rate of translation, modifying gene expression, inducing a hormetic response, modulating autophagy, or inducing mitochondrial function, antioxidant defense, or other metabolic processes. Although it is clear that each of the three branches of methionine metabolism - the methionine cycle, the transsulfuration pathway, and polyamine biosynthesis - plays a significant role in lifespan extension, how these branches crosstalk during regulation of lifespan is unknown. Moreover, how activity in these different branches of methionine metabolism change with age in different tissues and organs remains to be elucidated.

Permanently Boosting Levels of Natural Killer Cells in Mice to Increase Cancer Resistance

Researchers here demonstrate a very interesting approach to immunotherapy: they introduce engineered stem cells in mice that will give rise to additional natural killer T cells, boosting the capability of the immune system for the entire life span of the mouse. Even if this class of treatment is not actually permanent in the same way in humans, and merely long-lasting, it still seems a promising step towards enhancing the immune system at any age, not just trying to repair it when it fails in later life.

They've been called the "special forces" of the immune system: invariant natural killer T cells. Although there are relatively few of them in the body, they are more powerful than many other immune cells. Scientists have hypothesized that iNKT cells could be a useful weapon against cancer because it has been shown that they are capable of targeting many types of cancer at once - a difference from most immune cells, which recognize and attack only one particular type of cancer cell at a time. But most people have very low quantities of iNKT cells; less than 0.1% of blood cells are iNKT cells in most cases. Still, previous clinical studies have shown that cancer patients with naturally higher levels of iNKT cells generally live longer than those with lower levels of cells.

The researchers' goal was to create a therapy that would permanently boost the body's ability to naturally produce more iNKT cells. They started with hematopoietic stem cells - cells found in the bone marrow that can duplicate themselves and can become all types of blood and immune cells, including iNKT cells. The researchers genetically engineered the stem cells so that they were programmed to develop into iNKT cells.

They tested the resulting cells, called hematopoietic stem cell-engineered invariant natural killer T cells, or HSC-iNKT cells, on mice with both human bone marrow and human cancers - either multiple myeloma (a blood cancer) or melanoma (a solid tumor cancer) - and studied what happened to the mice's immune systems, the cancers and the HSC-iNKT cells after they had integrated into the bone marrow. They found that the stem cells differentiated normally into iNKT cells and continued to produce iNKT cells for the rest of the animals' lives, which was generally about a year.

While mice without the engineered stem cell transplants had nearly undetectable levels of iNKT cells, in those that received engineered stem cell transplants, iNKT cells made up as much as 60% of the immune systems' total T cell count. Plus, researchers found they could control those numbers by how they engineered the original hematopoietic stem cells. Finally, the team found that in both multiple myeloma and melanoma, HSC-iNKT cells effectively suppressed tumor growth.


FGF23, Klotho, and Vascular Calcification

Klotho and FGF23 interact with one another in a number of mechanisms that might explain the effects of klotho on longevity in mice: more klotho slows aging, while loss of klotho accelerates it. Vascular function is fairly high on that list, given the importance of the cardiovascular system in aging. The mechanism of interest in the research here is calcification of blood vessels, the dysfunction in cell populations in blood vessel walls that leads to mineralization akin to that involved in generation of bone tissue. Some of this is clearly the result of rising levels of cellular senescence and the harmful signaling that is produced by senescent cells. Investigations of the sort noted here are more concerned with proximate causes, however, in the sense of altered levels and interactions of various proteins.

Vascular calcification (VC) constitutes a major risk factor for cardiovascular (CV) morbidity and mortality and involves a complex regulated process of biomineralization that resembles osteogenesis. This process is mainly driven by the vascular smooth muscle cells (VSMCs), and includes the transformation of these cells into an osteoblastic phenotype.

Chronic kidney disease (CKD) is a major risk factor for CV disease (CVD) and is a clinical scenario closely related to the development of VC. In addition to the traditional CV risk factors, subjects with CKD are also exposed to other non-traditional factors predisposing for this pathology. Fibroblast growth factor (FGF) 23 is the most potent phosphatonin. This is an osteocyte-derived hormone produced in response to phosphate levels which, in combination with its cofactor Klotho, reduces the reabsorption of phosphate and the synthesis of active vitamin D in the kidneys. In patients with CKD, FGF23 concentrations increase with declining renal function and reach extremely high levels in end-stage renal disease. Clinical epidemiological studies have shown that FGF23 strongly predicts mortality in patients with CKD independently of other risk factors. These results suggest that FGF23 may causally be related to the high mortality observed in CKD patients and, importantly, that may exert direct effects on CV system besides its function as a phosphaturic hormone.

FGF23 binds to its cognate receptors (FGFRs), which are activated in the presence of the co-receptor Klotho. Our group and others described the expression of FGFR and Klotho in the human vascular wall, allowing to speculate that vascular tissue may be an objective for the actions of FGF23. Moreover, the synthesis of FGF23 by calcified vascular tissues and its contribution to CVD is an intriguing question not adequately studied. Only two previous works have explored the expression of FGF23 in calcified tissues, although solely coronary arteries and carotid atheroma plaques were analyzed. Moreover, the relationships of vascular FGF23 gene and protein expression levels with soluble FGF23 concentration and with the expression of Klotho and FGFRs in the vessels have not been previously established.

In this work, we determined the levels of both intact and fragmentary circulating FGF23 in 133 patients with established cardiovascular disease, the expression of FGF23, its receptors, and its co-receptor Klotho in vascular fragments of aorta, carotid, and femoral in 43 out of this group of patients, and in a control group of 20 organ donors. Patients with atherosclerosis and vascular calcification presented increased levels of FGF23 respect to the control group. Vascular immunoreactivity for FGF23 was also significantly increased in patients with vascular calcification as compared to patients without calcification and to controls. Finally, gene expression of FGF23 and RUNX2 were also higher and directly related in vascular samples with calcification. Conversely, expression of Klotho was reduced in patients with cardiovascular disease when comparing to controls. In conclusion, our findings link the calcification of the vascular tissue with the expression of FGF23 in the vessels and with the elevation of circulating levels this hormone.


Alzheimer's Disease as a Condition of Many Subtypes and Contributing Causes

Neurodegeneration in late life is a very complex phenomenon, and its complexity strains against the nice neat clinical definitions of disease found in the textbooks. Different patients with Alzheimer's disease can exhibit quite different mixes of various forms of pathology, developing at different paces and times: aggregates of amyloid-β, tau, and α-synuclein; vascular degeneration; markers of neuroinflammation; metabolic disruption similar to that of diabetes, and so forth. One case of Alzheimer's might be different enough from another to require a different designation. Thus researchers talk about defining subtypes of Alzheimer's disease, or that individual patients have Alzheimer's that is exacerbated by a comorbidity arising from other neurodegenerative processes.

Another way of looking at this is to categorize mechanisms that contribute to Alzheimer's. To what degree is a given set of mechanisms important in a given patient? A sizable amount of work has gone into investigation of processes and feedback loops other than the primary amyloid cascade hypothesis of the condition. It is an open question as to where all of these contributing aspects of the condition fit into a chain of cause and consequence, or whether the ordering of that chain is similar from patient to patient. Alzheimer's disease may well be a collection of distinct conditions that all happen to wind up in a similar end state.

The authors of this paper draw the gloomy conclusion that this complexity, and continued failures in the development of therapies based on the amyloid cascade hypothesis, imply that there are no silver bullets. I would argue otherwise, and say that instead comparatively simple points of intervention have not yet been developed fully. Senolytic therapies that clear senescent glial cells from the brain seem quite effective in animal models, for example. The approach of restoring lost drainage of cerebrospinal fluid, to clear out aggregates from the brain, also looks promising. There will be others. The complexity of aging emerges from simpler root causes, and there will always be some clever way to intervene at a point of maximum leverage.

Multi-Loop Model of Alzheimer Disease: An Integrated Perspective on the Wnt/GSK3β, α-Synuclein, and Type 3 Diabetes Hypotheses

Alzheimer's disease (AD) is among the most ominous of modern health epidemics. AD is not alone in its ascent. Other chronic diseases, particularly Parkinson's disease (PD), a neurodegenerative disorder associated with the build-up of α-synuclein protein and death of dopaminergic neurons, and type 2 diabetes mellitus (T2DM) are increasing in prevalence at similarly alarming rates. Although AD, PD, and T2DM share common risk factors, chief among these being age, there is more to their relationship. Evidence suggests that the pathophysiological mechanisms underlying AD, PD, and T2DM interact synergistically.

In addition to the well-known amyloid cascade hypothesis of AD, other hypotheses have been proposed that include: (1) the Wnt/Glycogen Synthase Kinase 3β (GSK3β) hypothesis, (2) the α-synuclein hypothesis, and (3) the type 3 diabetes hypothesis. Dsfunctional Wnt-signaling can contribute to the development of AD and its two pathological hallmarks, plaques and p-tau tangles. The canonical PD-associated protein α-synuclein may be locked in pathological positive feedback loops with Aβ and tau. Finally, insulin resistance in the brain, "type 3 diabetes," may contribute to development and exacerbation of AD. Each model interacts with the others. These interrelationships, make it clear that the pathology of AD is not a linear cascade, nor a simple feedback loop, but rather a network of cross-talking models and overlapping vicious cycles.

Given the cooperative and reinforced nature of this complex network, it is no surprise that the prototypical monotherapeutic approach to AD has reliably failed. Certainly, drugs that target key nodes within the network, such as GSK3β inhibitors or AKT activators, have shown promise in animal models, and this important work affords us valuable mechanistic insights. However, these pre-clinical successes generally have not translated into clinical success, at least not with the same degree of efficacy. This is likely because animal models harboring distinct AD-causing mutations and dysfunctions in particular linear pathways do not accurately recapitulate the complex pathologies underlying sporadic human AD. In brief, we are proposing that the single-target silver-bullet approach to AD drug discovery is doomed to fail and that we may only be able to treat or prevent AD by developing new multifaceted treatment options.

A Non-Invasive Approach to Measuring Cellular Senescence in the Kidney

Researchers here provide evidence that the presence in the urine of extracellular vesicles carrying p16 as a part of their cargo might be used as a way to assess cellular senescence levels in the kidney. The presence of lingering senescent cells increases with age, and these cells cause chronic inflammation and tissue dysfunction in proportion to their numbers. With rapid growth in the clinical development of senolytic drugs capable of clearing senescent cells from aged tissues, and the present availability of a few proven and potential senolytic treatments such as the dasatinib and quercetin combination, there is a strong need for ways to quantify the burden of senescent cells in humans. Simple, low-cost tests that can run before and after a senolytic treatment would go a long way towards quantifying the degree to which the presently available approaches actually work.

Hypertension may be associated with renal cellular injury. Cells in distress release extracellular vesicles (EVs), and their numbers in urine may reflect renal injury. Cellular senescence, an irreversible growth arrest in response to a noxious milieu, is characterized by release of proinflammatory cytokines. We hypothesized that EVs released by senescent nephron cells can be identified in urine of patients with hypertension.

We recruited patients with essential hypertension (EH) or renovascular hypertension and healthy volunteers. Renal oxygenation was assessed using magnetic resonance imaging and blood samples collected from both renal veins for cytokine-level measurements. EVs isolated from urine samples were characterized by imaging flow cytometry based on specific markers, including p16 (senescence marker), calyxin (podocytes), urate transporter 1 (proximal tubules), uromodulin (ascending limb of Henle's loop), and prominin-2 (distal tubules).

Overall percentage of urinary p16+ EVs was elevated in EH and renovascular hypertension patients compared with healthy volunteers and correlated inversely with renal function and directly with renal vein cytokine levels. Urinary levels of p16+/urate transporter 1+ were elevated in all hypertensive subjects compared with healthy volunteers, whereas p16+/prominin-2+ levels were elevated only in EH versus healthy volunteers and p16+/uromodulin+ in renovascular hypertension versus EH.

In conclusion, levels of p16+ EVs are elevated in urine of hypertensive patients and may reflect increased proximal tubular cellular senescence. In EH, EVs originate also from distal tubules and in renovascular hypertension from Henle's loop. Hence, urinary EVs levels may be useful to identify intrarenal sites of cellular senescence.


A Skeptical Review of the Evidence for Metformin

This review paper more or less leans towards my thoughts on metformin as a treatment to slow aging: the animal data is not great, the human data is a single study, the effect size on life span is far too small to care about, and the detrimental side effects are large in comparison to that effect size. The strategy of upregulating stress response mechanisms via drugs such as metformin is a poor strategy for long-lived species, as we clearly don't exhibit the sizable gains in life span that occur in short lived species such as mice under these circumstances. Metformin, in turn, is a low performance example of this strategy, much worse than, say, the practice of calorie restriction or mTOR inhibitors.

Metformin is sometimes proposed to be an "anti-aging" drug, based on preclinical experiments with lower-order organisms and numerous retrospective data on beneficial health outcomes for type 2 diabetics. Large prospective, placebo-controlled trials are planned, in pilot stage, or running, to find a new use (or indication) for an aging population. In 2015, Nir Barzilai met with regulators from the FDA to discuss the now famous phase III multi-site TAME (Targeting Aging with Metformin) trial. The acronym chosen and the intention behind it - namely, that aging is a "disorder" that can be treated like any other disease - was a clear provocation. The FDA's mandate is to regulate medications and devices to cure diseases or aid in their diagnosis, but aging is not (yet) an indication. Interestingly, frailty is missing from the proposed composite outcome. Other ongoing trials (e.g., NCT02570672) with metformin provide arguments that frailty may be an important endpoint. It will be interesting to compare the results with the ongoing fisetin trial (NCT03675724).

Although widely cited as evidence for the small effects of 0.1% metformin in the diet on the lifespan of older male inbred mice, earlier results obtained by researchers should be dismissed: the National Institute on Aging Interventions Testing Program could not replicate the findings regarding an extension of the lifespan with 0.1% metformin. The negative results were obtained at three different locations using genetically heterogeneous female and male mice.

The rationale for the ongoing or planned metformin trials is almost exclusively based on observations (associations) of potential benefits in a diabetic (or prediabetic) population. Its efficacy even in an at-risk cohort of aged people has not yet been proven. Metformin is associated with a higher risk of vitamin B12 and vitamin B6 deficiency, which may result in an increased risk of cognitive dysfunction. Supplementation is strongly recommended to metformin users.

Of greater concern are the results of small trials in which the effects of metformin on metabolic responses to exercise or on cardiorespiratory fitness were tested. In a placebo-controlled, double-blind, crossover trial with healthy young subjects, metformin caused a small but significant decline in maximal aerobic capacity. A double-blind, placebo-controlled landmark trial with older adults with one risk factor for type 2 diabetes investigated the effects of metformin and 12 weeks of aerobic exercise. Contrary to expectations - namely, that the effects of exercise and the drug would be additive - "metformin attenuated the increase in whole-body insulin sensitivity and abrogated the exercise-mediated increase in skeletal muscle mitochondrial respiration."


ApoE Levels Rise with Age and Degrade the Ability to Regenerate Bone

ApoE is a important protein in lipid metabolism, one of those responsible for transporting cholesterols and other lipids around the body. In today's open access research, the authors present evidence for rising levels of ApoE with aging to degrade the ability of bone to regenerate. This is unfortunate, because it will not be straightforward to just reduce ApoE levels. The protein is vital; a number of serious inherited conditions involve ApoE mutation that leads to greatly increased lipid levels on the bloodstream and organs.

Bone regeneration, and normal tissue maintenance of bone for that matter, is a balance between constant creation and destruction of extracellular matrix structures. Osteoblast cells build bone, and osteoclasts tear it down. Age-related loss of bone density and strength is the result of a growing imbalance that favors osteoclast activity. There is good evidence for numerous mechanisms to be important here, including the usual suspects such as the inflammatory signaling produced by senescent cells. The data here for reversal of loss of regenerative capacity via reduced ApoE levels is quite compelling as an argument for this to be an important proximate mechanism, however.

Protein prevalent in older people could be key to healing bones

Researchers confirmed that older people have more Apolipoprotein E, ApoE for short, than younger people. (If that protein name rings a bell, it's because ApoE is also implicated in Alzheimer's and heart disease). The team found that 75-85 year olds had twice as much ApoE in their bloodstreams as 35-45 year olds, then found the same was true for 24-month-old mice versus 4-month-old mice, which approximate the same human age ranges. Next, they wanted to figure out if and how ApoE affects the multi-step process of bone healing. When you break a bone, your body sends signals through the bloodstream to recruit cells to fix it. Some of those recruits, specifically skeletal stem cells, build up cartilage as a temporary scaffolding to hold the fracture together.

In the next step, more recruited cells mature into osteoblasts, bone-building cells, which lay strong, dense bone cells on top of the cartilage scaffolding. Finally, a different kind of cell eats up the cartilage scaffolds and osteoblasts fill those holes with bone. That's if the bone healing process works perfectly. But the researchers found that if they added ApoE to a petri dish with skeletal stem cells, fewer cells developed into osteoblasts and the osteoblasts were worse at building bones. Next, the researchers created an intervention by injecting a virus which keeps mice from making ApoE protein. Circulating ApoE levels dropped by 75 percent and the healed bones contained one and a half-times more strong, hard bone tissue than bones of untreated mice.

Lowering circulating apolipoprotein E levels improves aged bone fracture healing

In our previous work investigating aged bone regeneration, we identified apolipoprotein E (ApoE) to be one of many candidates potentially involved in aged bone fracture healing. ApoE is a widely expressed lipoprotein classically associated with lipid metabolism and fatty acid transport. ApoE polymorphisms are present in 20% of the population and are associated with hypercholesterolemia, atherosclerosis, and Alzheimer's disease. More recently, clinical evidence has revealed that these ApoE polymorphisms are also associated with decreased bone mineral density and increased risk of hip and vertebral fracture. Mouse models lacking ApoE expression display increased cortical thickness, trabecular number, and bone mineral density. However, a role for ApoE in fracture healing and musculoskeletal aging remains to be investigated.

Here, we sought to understand the role of ApoE in age-associated deficiencies in bone fracture healing. Our previous work has established the importance of circulating factors in the age-associated impairment of bone regeneration. Here, we use our established tibial fracture model coupled with μCT and histological analysis as well as our parabiosis models to identify a role for circulating ApoE in bone fracture healing. We identify ApoE as a negative regulator of osteoblast differentiation and combine this work with functional metabolic assessment and transcript analysis to identify the mechanism by which ApoE influences osteoblast differentiation. Finally, we identify that lowering circulating ApoE levels, using siRNA strategies, in aged mouse models leads to improved bone fracture healing. Collectively, our findings demonstrate that ApoE impairs bone fracture healing in an age-dependent manner by decreasing osteoblast differentiation.

Altered Calcium Transport in Aging Mitochondria is Maladaptive

Mitochondria are the power plants of the cell, responsible for packaging energy store molecules used to power cellular processes. There are hundreds of them in any given cell, the descendants of ancient symbiotic bacteria. They replicate by fission, like bacteria, and carry a remnant of their original DNA. Mitochondrial function declines with age, a problem that appears to stem from an imbalance in mitochondrial fission that in turn impairs the ability of the cell to clear out worn and malfunctioning mitochondria via the process of autophagy. Exactly why this imbalance arises is poorly understood, but it can be added to the long, long list of maladaptive processes that emerge in response to the underlying molecular damage of aging.

Researchers here focus on another maladaptive aspect of mitochondrial function in aging cells: they exhibit altered calcium transport, which may initially compensate for other shortfalls, but then ultimately further contributes to the faltering of mitochondrial function. This is very much a downstream consequence of deeper problems.

Sometimes the more a person tries to fix a seemingly minor problem, the worse things become. Cells are no different, it turns out, though attempting to compensate for what begins as a minor deficiency or dysfunction can be dire. In the case of Alzheimer's disease, researchers now show that mitochondrial calcium transport remodeling - what appears to be an attempt by cells to compensate for flagging energy production and metabolic dysfunction - while initially beneficial, ultimately becomes maladaptive, fueling declines in mitochondrial function, memory, and learning.

Altered calcium regulation and metabolic dysfunction have been suspected of contributing to neuronal dysfunction and Alzheimer's development. Calcium transport into mitochondria plays an important part in many cellular functions and requires the involvement of multiple proteins to be carried out effectively. Among the key regulators of this process is a protein known as NCLX, which previously was discovered to mediate calcium efflux from heart cells. NCLX expression is also important in mitochondrial calcium efflux in neurons.

In a new study, researchers examined the role of mitochondrial calcium uptake by neurons in Alzheimer's disease. To do so, the team used a mouse model of familial Alzheimer's disease in which animals harbored three gene mutations that give rise to age-progressive pathology comparable to Alzheimer's progression in human patients. As mice carrying the three mutations aged, the researchers observed a steady reduction in NCLX expression. This reduction was accompanied by decreases in the expression of proteins that limit mitochondrial calcium uptake, resulting in damaging calcium overload. NCLX loss was further linked to increases in the production of cell-damaging oxidants. When NCLX expression was restored, levels of harmful protein aggregates declined, neuronal mitochondrial calcium homeostasis was reestablished, and mice were rescued from cognitive decline.

"Our findings indicate that maladaptive remodeling of pathways to compensate for abnormalities in calcium regulation, which perhaps are meant to maintain energy production in cells, lead to neuronal dysfunction and Alzheimer's pathology. Moreover, our data suggest that amyloid beta and tau pathology actually lie downstream of mitochondrial dysfunction in the progression of Alzheimer's disease, which opens up a new therapeutic angle."


The Boost to the Unfolded Protein Response Achieved via Exercise Declines with Age

Exercise achieves benefits to health in large part through upregulation of cellular maintenance processes. In this way it is similar to the practice of calorie restriction, but the outcome is of a lesser degree - exercise does not extend life span in laboratory species, while calorie restriction does. Nonetheless, exercise is certainly beneficial. One of the cellular maintenance processes involved is the unfolded protein response, which, as the name might suggest, clears out proteins that are improperly folded, or have otherwise become stuck at the folding stage of protein manufacture, in the endoplasmic reticulum structure of the cell. Like other maintenance processes, the unfolded protein response becomes less effective with age, for reasons that are far from fully explored. Here, researchers demonstrate this diminished effectiveness in the context of the response to exercise.

Aging is associated with the loss of skeletal muscle mass, quality, and function; decrements that have a negative influence on health span. Resistance exercise improves muscle mass and function, but there is emerging evidence that the molecular and cellular responses to anabolic stimuli (e.g., exercise and nutrition) are attenuated in older adults; a phenomenon termed anabolic resistance. The unfolded protein response (UPR) has emerged as a key regulatory pathway in skeletal muscle protein quality control and adaptations to exercise. Early evidence points to altered UPR as an explanation for age and disease related changes in protein folding and accumulation and aggregation of proteins within the endoplasmic reticulum (ER).

The influence of age on skeletal muscle adaptive UPR in response to exercise, and the relationship to other key exercise-responsive regulatory pathways is not well-understood. We evaluated age-related changes in transcriptional markers of UPR activation following a single bout of resistance exercise in 12 young (27 ± 5yrs) and 12 older (75 ± 5yrs) healthy men and women. At baseline, there were modest differences in expression of UPR-related genes in young and older adults. Following exercise, transcriptional markers of UPR pathway activation were attenuated in older adults compared to young based on specific salient UPR-related genes and gene set enrichment analysis. The coordination of post-exercise transcriptional patterns between the UPR pathway, p53/p21 axis of autophagy, and satellite cell (SC) differentiation were less evident in older compared to young adults.

In conclusion, older adults exhibited decreased markers of UPR activation and reduced coordination with autophagy and SC-associated gene transcripts following a single bout of unaccustomed resistance exercise. In contrast, young adults demonstrated strong coordination between UPR genes and key regulatory gene transcripts associated with autophagy and SC differentiation in skeletal muscle post-exercise. Taken together, the present findings suggest a potential age-related impairment in the post-exercise transcriptional response supporting activation of the UPR and coordination with other exercise responsive pathways (i.e., autophagy, SC differentiation) in skeletal muscle that is likely to contribute to sarcopenia and age-related attenuation of adaptive responses to exercise.


Senescent Cells Implicated in Age-Related Changes in Blood Clotting

Senescent cells are created constantly in the body as the result of a number of processes: the Hayflick limit, wound healing, a toxic local environment, DNA damage, and so forth. Near all are destroyed quite quickly, either via programmed cell death or by the immune system. Some few linger, however, and secrete a potent mix of molecules known as the senescence-associated secretory phenotype (SASP). The SASP produces wide-ranging damage and dysfunction in tissues, causing issues such as chronic inflammation, fibrosis, and harmful behavior or increased senescence in nearby cells. Thus senescent cell burden is one of the important causes of aging, and efforts to produce senolytic therapies capable of selectively destroying these cells are a very important new branch of medicine.

As noted in today's scientific materials, researchers have recently provided data to associate the burden of senescent cells in older individuals with detrimental changes in blood clotting. This adds one more item to a very long list of harmful effects resulting the SASP. With age, blood clots form more readily, and in inappropriate circumstances, such as inside major blood vessels. This can cause serious issues such as thrombosis, the blocking of blood vessels and consequent ischemia, or worse, such as a stroke or heart attack should a sizable clot fragment and the fragments block a more vital blood vessel elsewhere.

The data here associating components of the SASP with increased susceptibility to blood clotting is interesting to compare with a recent review paper on changes in platelet function with age. The biochemistry of the age-related hyperactivity of platelets, leading to increased clotting, has been examined in a proximate sense, but reaching backwards to root causes is something that the research community has never been all that good at following through on. The work here is a good example of starting with a known cause of aging and working forwards, a much more efficient approach, and one that must become more widespread in the research community if we are to see meaningful progress in treatments for age-related conditions in the years ahead.

Cellular senescence is associated with age-related blood clots

Cells that become senescent irrevocably stop dividing under stress, spewing out a mix of inflammatory proteins that lead to chronic inflammation as more and more of the cells accumulate over time. Researchers have identified 44 specific senescence-associated proteins that are involved in blood clotting, marking the first time that cellular senescence has been associated with age-related blood clots. "The incidence of venous thrombosis, which includes deep vein thrombosis and pulmonary embolism is extremely low until the age of 45, when it begins to rise rapidly. Over time it becomes a major risk factor for death. By 80, the condition affects five to six people per thousand individuals. Blood clots are also a serious side effect of chemotherapy, which sets off a cascade of senescence in those undergoing treatment. That's why blood thinners, which carry their own risks, are often included in treatment protocols."

In this study, researchers validated the expression of some of the specific factors in cultured cells and in mice, which were treated with doxorubicin, a widely-used chemotherapy drug which induces widespread senescence. Those mice showed increased blood clotting, similar to what happens in humans who undergo chemotherapy. "Conversely, when we selectively removed senescent cells in specially bred transgenic mice, the increased clotting caused by doxorubicin went away."

SILAC Analysis Reveals Increased Secretion of Hemostasis-Related Factors by Senescent Cells

Cellular senescence irreversibly arrests cell proliferation, accompanied by a multi-component senescence-associated secretory phenotype (SASP) that participates in several age-related diseases. Using stable isotope labeling with amino acids (SILACs) and cultured cells, we identify 343 SASP proteins that senescent human fibroblasts secrete at 2-fold or higher levels compared with quiescent cell counterparts. Bioinformatic analysis reveals that 44 of these proteins participate in hemostasis, a process not previously linked with cellular senescence.

We validated the expression of some of these SASP factors in cultured cells and in vivo. Mice treated with the chemotherapeutic agent doxorubicin, which induces widespread cellular senescence in vivo, show increased blood clotting. Conversely, selective removal of senescent cells using transgenic p16-3MR mice showed that clearing senescent cells attenuates the increased clotting caused by doxorubicin. Our study provides an in-depth, unbiased analysis of the SASP and unveils a function for cellular senescence in hemostasis.

An Interview with Tristan Edwards of Life Biosciences

Alongside Juvenescence, Life Biosciences is one of the first large investment concerns wholly dedicated to the growing longevity industry. The Life Biosciences principals take the approach of providing the extensive supporting infrastructure needed to wrap a company around a senior scientist in the field of aging research, and then guide their work towards commercialization. Most scientists have very little interest in founding a company, and in any case lack the skills needed to do so. This approach of providing an environment that operates in much the same way as academia from the perspective of the researcher, in which the business side of things is handled, is a good way to accelerate progress in a field that presently lacks a sufficiently large population of entrepreneurs for companies to emerge naturally at a good pace.

How far along is longevity in becoming a defined category for investors? Put it on a scale of 0-10 for us. If fintech has developed to a nine or a ten, where would you score longevity?

From an investment perspective I would say it's a one or a two. But I believe that will change very quickly. I think the scale will go from a two to an eight in the next four to five years. Like the Internet of Things, or Artificial Intelligence before it, in the next few years I can't imagine a single person on the planet not being aware of the ability to extend lifespan and healthspan, both as an industry and as a benefit to humankind.

So, a major shift in our thinking is on the way?

In 1903, the Wright brothers defied expectation and took their first flight. We have the photo of this on our office wall, to remind us of who we are. The idea of humans being able to fly back then was crazy; most people were saying it couldn't be done. Yet after they left the earth's gravity, it didn't take mankind years to accept it. We immediately forgot that it was crazy. All we needed was proof that it could be done, and we never looked back. That's exactly where we are with longevity sciences. Longevity research has been evolving as a legitimate science for many years. But I think we are at the cusp of dramatic change. We'll see more and more bright young minds focusing on longevity, and we will soon treat aging. Eventually, we're talking about adding another 20 - 30 years to the average lifespan with none of the diseases of aging: Parkinson's, Alzheimer's, type 2 diabetes, etc. In other words, not only expanding lifespan but what we call "healthspan," the period during which the individual can live a healthy, productive life.

Does all this development mean big institutional investors will soon be paying attention?

Plenty already are. The science, however, has to build to a point where the rounds are large enough for them to get involved. Once you start raising $100m to $200m rounds, they'll start paying real attention and investing. The rounds must be large enough for the mandates to allow and value checks must be in place in new areas; this can be tough to do. As the science progresses, we see the investment interest ramping up, with bigger contributors stepping in. A lot also depends on how quickly some institutions learn to adapt. By "adapt" I mean simply this: There's a long-held understanding that Big Pharma relies on illness for profits. But if they reframe their mission as being in the healthspan business, then the longevity revolution is valuable for them. It's my hope that Pharma embraces this change as a wonderful and necessary way for them to evolve their business in a much more effective way.


Risk Factors versus Lifestyle Choices in the Mortality of Old Age

Environmental and lifestyle choices, as numerous epidemiological studies have demonstrated, have considerable influence over health and mortality in late life. This open access paper balances lifestyle choices against a range of environmental factors and measures of the progression of aging. The authors find that a healthy lifestyle can only partially offset the effects of having a greater burden of age-related damage and its consequences, or, separately, the impact of low socioeconomic status. The former makes a great deal of sense, given the inevitability of aging as matters currently stand, with even the healthiest succumbing, while the latter is an interesting finding. It remains unclear as to the mechanisms linking socioeconomic status to aging: wealth, education, intelligence, stress, access to medical services, and other factors are closely tied and hard to pick apart in the human data.

Annual mortality among oldest-old individuals was reduced by somewhere between 0.2% and 1.3% from 1998 to 2008 in China. Impaired cognitive functions were independent predictors of all-cause mortality in very old people. Moreover, the risk of mortality is very high for the oldest-old with disabilities. Additionally, socioeconomic inequalities, obesity, cardiovascular factors, and chronic diseases are associated with mortality in the oldest-old. Conversely, healthy lifestyle practices, such as consumption of fruits and vegetables, social participation, and maintaining a normal weight, are associated with lower mortality. The question remains as to whether a healthy lifestyle and behavioral factors (e.g., never smoking and physical training) can somehow compensate for the harmful effects of the risk factors on mortality.

In this large, nationwide cohort study of Chinese oldest-old (80 years of age and older), we found that rural residence, not in marriage, lower economic level, physical disability, impaired cognitive function, and comorbidity are independent risk factors for mortality. Using these factors, we computed a weighted "risk score." Because never smoking, never drinking, doing physical exercise, having an ideal diet, and a normal weight were independently associated with lower mortality, we also combined them to compute a weighted "protection score." Both scores were divided into lowest, middle, and highest groups using their tertiles.

In joint effect analyses, participants with the combined highest-risk score and lowest-protection score profile had a nearly threefold higher joint death risk. These analyses show that adherence to a healthy lifestyle counteracts the negative effect of risk factors on all-cause mortality in the oldest-old by more than 20%.


RAGE and Chronic Inflammation in Aging

Chronic inflammation is a very important downstream consequence of molecular damage in the progression of aging, arising from numerous causes. The past decade of work on the presence of lingering senescent cells in old tissues indicates that their signaling is significant cause. In animal studies, removing senescent cells can reverse the course of many age-related and other conditions that are primarily inflammatory in nature. Visceral fat tissue in excess amounts can accelerate the production of senescent cells, but it also generates inflammation through other mechanisms, such as debris from dead cells, signaling by non-senescent fat cells that resembles the signaling of infected cells, and so forth.

There are also numerous other contributing factors relating to the growing dysfunction of the immune system, or some of the metabolic issues that accompany excess fat tissue. The one examined in today's open access paper is the interaction of advanced glycation end-products (AGEs) with the receptor for AGEs (RAGE). There are a couple of different issues in aging, type 2 diabetes, and obesity relating to AGEs. The more interesting one for the SENS rejuvenation research community is the accumulation of persistent cross-links in the extracellular matrix formed from glucosepane; these cross-links degrade tissue elasticity, which in turn contributes to hypertension via arterial stiffening, among many other issues. However, there are many other short-lived AGEs that arise from the diet and from cellular metabolism, and which are particularly prevalent in the distorted metabolism of obese and diabetic patients.

These short-lived AGEs produce inflammation by overactivating RAGE; this mechanism has been fairly well studied in past years, particularly in diabetic patients. As the authors of this paper note, however, even well studied parts of human biochemistry have plenty of unanswered questions left for researchers to work on. As for a number of processes that may operate to a significant degree in both diabetes and aging, it is an open question as to the degree to which RAGE is important in purely age-related dysfunction, versus other mechanisms such as the accumulation of senescent cells. Older people tend to have more fat tissue, which obscures the matter.

Is RAGE the receptor for inflammaging?

In its full-length form the receptor for advanced glycation end products, RAGE, is a multi-ligand, transmembrane receptor promoting activation of key pro-inflammatory and pro-oxidative pathways. The deleterious effects of its activation via the binding of AGEs (the advanced glycation end products after which it is named) are widely reported, especially in diabetes mellitus. Indeed, our current understanding of RAGE relies heavily upon research on this metabolic disorder, but it is simplistic to apprehend this receptor solely within a diabetic context or through its interactions with AGEs. RAGE is more broadly implicated in both immunity and inflammation: more than 28 RAGE ligands are known, many of which are damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs).

RAGE can thus be more accurately considered a pattern recognition receptor (PRR), and has been labelled a "noncanonical Toll-like receptor (TLR)" by some authors. This wider involvement of RAGE signalling nevertheless remains poorly-studied relative to research involving diabetes and AGEs, but evidence is accumulating of its role in what has come to be known as "inflammaging". RAGE deletion has been shown to be protective against both cardiovascular disease and Alzheimer's disease in RAGE-/- mice, and while the impact of anti-RAGE therapeutics remains to be demonstrated in humans, laboratory results highlight the potential of targeting this receptor to address multiple public health issues.

RAGE has obvious similarities with other PRRs and there are acknowledged pro-aging mechanisms such as oxidative stress, mitochondrial dysfunction or inflammasome activation resulting from its interaction with several of its ligands. The concomitant, age-related increase of circulating DAMPs, and the expression of RAGE on many cell membranes, even in the absence of a pathological event, could favour low-grade, persistent, pro-inflammatory processes which in turn could drive increased production of DAMPs and expression of RAGE. This pro-aging vicious circle of events places RAGE firmly in the spotlight as a key-actor in inflammaging, not least because senescent cells also produce RAGE ligands like HMGB1 and S100s.

This hypothesis is attractive and opens up significant possibilities in the development of anti-RAGE therapeutics, but many questions remain. To what extent do the different RAGE ligands compete for binding, and how does this competition modulate its activation? Are the activated signalling pathways ligand-specific, or perhaps specific to the configuration of RAGE in its various forms? Are there negative effects to RAGE inhibition?

Fitter, Thinner Older Adults Have a Measurably Different Gut Microbiome

In recent years, researchers have demonstrated that the microbiome of the gut is influential over the pace of aging. Dietary changes, immune system changes, tissue changes, and microbiome population changes all take place and interact with one another with advancing age. There is evidence for changes in the microbiome to aggravate the immune system into chronic inflammation, and evidence for declining immune function to lead to unhelpful changes in the balance of microbes. Some people have better microbiomes, such as athletes tending to have microbes that secrete compounds such as proprionate that can incrementally improve health. In animal models, transplanting gut microbes from young to old animals improves the health and longevity of the older animals.

In this broader context, we should probably expect fitter adults to have a measurably different gut microbiome in comparison to their less fit and overweight peers. Are those different bacteria helping to maintain fitness? The evidence here suggests that they are, but questions of causation remain: is it diet, weight, and inflammation that determines whether or not helpful bacteria are present, or do natural variations in bacterial populations between individuals make it easier or harder to maintain fitness?

The gut-muscle axis, or the relationship between gut microbiota and muscle mass and physical function, has gained momentum as a research topic in the last few years as studies have established that gut microbiota influences many aspects of health. While researchers have begun exploring the connection between the gut microbiome, muscle, and physical function in mice and younger adults, few studies have been conducted with older adults. To gain insight into this population, the researchers compared bacteria from the gut microbiomes of 18 older adults with high-physical function and a favorable body composition (higher percentage of lean mass, lower percentage of fat mass) with 11 older adults with low-physical function and a less favorable body composition. The small study identified differences in the bacterial profiles between the two groups.

Similar bacterial differences were present when mice were colonized with fecal samples from the two human groups, and grip strength was increased in mice colonized with samples from the high-functioning older adults, suggesting a role for the gut microbiome in mechanisms related to muscle strength in older adults. Specifically, when compared to the low-functioning older adult group, the researchers found higher levels of Prevotellaceae, Prevotella, Barnesiella, and Barnesiella intestinihominis - all potentially good bacteria - in the high-functioning older adults and in the mice that were colonized with fecal samples from the high-functioning older adults.

"While we were surprised that we didn't identify a role for the gut microbiome on the maintenance of body composition, with these results we now start to understand the role of gut bacteria in the maintenance of muscle strength in older adults. For example, if we were to conduct an intervention to increase Prevotella levels in the gut microbiome, we would expect to see an increase in muscle strength if these bacteria are involved. Prevotella's role in the maintenance of muscle strength in older adults is one area we expect to continue to explore."


Exosomes Improve Collagen Production in Aged Skin

Loss of collagen in the extracellular matrix is one of the manifestations of aging in skin. There are any number of very marginal approaches intended to improve matters presently available in clinics and stores, very few of which in any way address the underlying causes, or in only very minor ways if they do. Delivery of signals generated by healthy skin cells is an approach that might be more effective, but again this doesn't address the underlying causes of skin aging - it is an attempt to override cellular reactions to the aged environment. In this vein, researchers here demonstrate the harvesting of exosomes, small membrane bound packages that carry signals between cells, from cell cultures, and their delivery to aged skin as a possible therapy.

Researchers have shown that exosomes harvested from human skin cells are more effective at repairing sun-damaged skin cells in mice than popular retinol or stem cell-based treatments currently in use. Additionally, the nanometer-sized exosomes can be delivered to the target cells via needle-free injections. Exosomes are tiny sacs (30 - 150 nanometers across) that are excreted and taken up by cells. They can transfer DNA, RNA, or proteins from cell to cell, affecting the function of the recipient cell. In the regenerative medicine field, exosomes are being tested as carriers of stem cell-based treatments for diseases ranging from heart disease to respiratory disorders.

To test whether exosomes could be effective for skin repair, researchers first grew and harvested exosomes from skin cells. They used commercially available human dermal fibroblast cells, expanding them in a suspension culture that allowed the cells to adhere to one another, forming spheroids. The spheroids then excreted exosomes into the media. "These 3D structures generate more procollagen - more potent exosomes - than you get with 2D cell expansion."

In a photoaged, nude mouse model, the researches tested the 3D spheroid-grown exosomes against three other treatments: retinoid cream; 2D-grown exosomes; and bone marrow derived mesenchymal stem cells (MSCs) exosomes, a popular stem cell-based anti-aging treatment currently in use. The team compared improvements in skin thickness and collagen production after treatment. They found that skin thickness in 3D exosome treated mice was 20% better than in the untreated and 5% better than in the MSC-treated mouse. Additionally, they found 30% more collagen production in skin treated with the 3D exosomes than in the MSC treated skin, which was the second most effective treatment.


Conversion of Glial Cells into Neurons as an Approach to Regeneration in the Brain

The authors of today's research report on success in use of a gene therapy to convert glial cells into neurons in a living mouse brain, and thereby improve the normally limited recovery that takes place following brain injury, such as that caused by a stroke. A number of research groups are investigating this class of approach to enhance regeneration in the brain, an organ that has little capacity to repair itself. The capacity that does exist is generated by neural stem cells that, arguably, continue to produce new neurons at some pace throughout life. As for all stem cell populations, activity declines with age, however. An increased supply of new neurons, provided that they are capable of correctly maturing and integrating into neural circuits, should prove beneficial.

Interestingly, increasing the supply of neurons is not just relevant to regeneration in the brain. Functions such as memory rely on changes in neural networks, and in turn on a supply of new neurons. It is possible that increasing the pace at which new neurons emerge could improve cognitive function even in younger people. We are a long way removed from that sort of application of new biotechnology, however - the focus today is very much on addressing age-related conditions.

Gene therapy helps functional recovery after stroke

Researchers have pioneered a new approach to regenerate functional neurons using glial cells, a group of cells surrounding every single neuron in the brain that provide essential support to neurons. Unlike neurons, glial cells can divide and regenerate themselves, especially after brain injury. Researchers previously reported that a single genetic neural factor, NeuroD1, could directly convert glial cells into functional neurons inside mouse brains with Alzheimer's disease, but the total number of neurons generated was limited. The research team believed that this limited regeneration was due to the retroviral system used to deliver NeuroD1 to the brain. In the current study, the research team used the AAV viral system, which is now the first choice for gene therapy in the nervous system, to deliver NeuroD1 into mouse motor cortex that had suffered from stroke.

Many neurons die after stroke but surviving glial cells can proliferate and form a glial scar in the stroke areas. The AAV system was designed to express NeuroD1 preferentially in the glial cells that form these scars, turning them directly into neuronal cells. Such direct glia-to-neuron conversion technology not only increased neuronal density in the stroke areas, but also significantly reduced brain tissue loss caused by the stroke.

"The most exciting finding of this study is to see the newly converted neurons being fully functional in firing repetitive action potentials and forming synaptic networks with other preexisting neurons. They also send out long-range axonal projections to the right targets and facilitate motor functional recovery. "Because glial cells are everywhere in the brain and can divide to regenerate themselves, our study provides the proof-of-concept that glial cells in the brain can be tapped as a fountain of youth to regenerate functional new neurons for brain repair not only for stroke but also for many other neurological disorders that result in neuronal loss."

A NeuroD1 AAV-Based Gene Therapy For Functional Brain Repair After Ischemic Injury Through In Vivo Astrocyte-To-Neuron Conversion

Adult mammalian brains have largely lost neuroregeneration capability except for a few niches. Previous studies have converted glial cells into neurons, but the total number of neurons generated is limited and the therapeutic potential is unclear. Here, we demonstrate that NeuroD1-mediated in situ astrocyte-to-neuron conversion can regenerate a large number of functional new neurons after ischemic injury. Specifically, using NeuroD1 AAV-based gene therapy, we were able to regenerate one third of the total lost neurons caused by ischemic injury and simultaneously protect another one third of injured neurons, leading to a significant neuronal recovery. RNA-sequencing and immunostaining confirmed neuronal recovery after cell conversion at both the mRNA level and protein level.

Brain slice recordings found that the astrocyte-converted neurons showed robust action potentials and synaptic responses at 2 months after NeuroD1 expression. Tracing revealed long-range axonal projections from astrocyte-converted neurons to their target regions in a time-dependent manner. Behavioral analyses showed a significant improvement of both motor and cognitive functions after cell conversion. Together, these results demonstrate that in vivo cell conversion technology through NeuroD1-based gene therapy can regenerate a large number of functional new neurons to restore lost neuronal functions after injury.

Aging Biotech Info is a Curated List of Companies in the Longevity Industry

Karl Pfleger is one of the small community of angel investors and philanthropists who collectively initially supported the first rejuvenation biotechnology companies to emerge in this present generation of the longevity industry. Here he is performing the public service of publishing a curated list of biotechnology companies in the industry, startups that are either definitively or at least arguably working on a means to intervene in important mechanisms of aging, along with their targets and progress to date. That there are still fewer than 100 such companies indicates that this is very much an industry in its initial growth phase - but growth is certainly happening. The sizable pools of venture funding dedicated to the longevity industry, such as Juvenescence and Life Biosciences are attracting new entrepreneurs, and the scientific community is starting to realize that the prospects for advancing their research programs into clinical translation have greatly improved these past few years.

Chronic diseases of aging have over the past century taken over from infectious diseases as the predominant causes of death and suffering. The science of aging has shown over the past few decades that certain slow biological changes collectively underlie most (if not all) chronic diseases. The aging and longevity field, the understanding of these slow changes and how to interfere with them, is currently a small part of the overall medical, healthcare, and biotech spaces, but the efficiency of targeting the underlying causes of multiple diseases will rapidly cause aging to grow to become a much larger portion.

The aging and longevity field has recently grown to the point where it is difficult to follow important developments, even for insiders. There are books, journals, and blogs, but few sources of structured information to refer to for broader context or to consult for targeted inquiries, particularly few focused narrowly on aging defined as the underlying molecular causes of multiple age-related diseases.

As an especially important example, the internet previously had no reasonably comprehensive and precise list of companies with therapies or diagnostics for underlying aging in the above sense. Some argue that aging will be a scientific, commercial, and cultural revolution to rival any others. What is even more certain is that the field is important and of interest to many, so concise ways to pay attention will be useful. This will be a living site with ongoing updates. Focus will be on content, not flashiness, with the goal being utility for the community, those interacting with it, and the wider interested public.


ADRB1 Mutation Grants a Lesser Need for Sleep, and thus a Longer Subjective Life

We lose a third of our life to sleep. If we didn't need to sleep at all, then we would have the experience of living 50% longer, considered subjectively. We would accomplish much more, experience much more. There are, unfortunately, few useful ways to safely reduce the amount of time spent asleep, without reductions in the quality of life while awake. Here, researchers report on a rare human genetic variant that manifests itself in a family whose members with the mutation need comparatively little sleep to be fully rested, and who appear to be otherwise unaffected by this genetic difference.

This discovery may well prove to be the basis for enhancement treatments to reduce required sleep time in the years ahead. We should consider the caveats, however: sleep appears to be important in clearance of some aggregates from the brain, and it could be the case that individuals who sleep less have raised rates of neurodegenerative disease in late life, but these possible risks and associations have not yet been evaluated.

An understanding of the regulatory mechanism for sleep lays at the foundation for healthy living and aging. Sleep behavior has long been thought to be regulated by the interactions of circadian clock and sleep homeostasis pathways. In humans, variations of genetically inherited sleep features in the population have been recognized for a long time. Importantly, human sleep has unique features that are different from that of animal models. For example, human sleep is usually consolidated, whereas mice sleep throughout the 24 hour day. Drosophila sleep-like behavior is consolidated into one long period, but the level of similarity between the Drosophila and human molecular regulatory mechanisms remains unclear.

Previously, we identified a series of genetic variations that influence the timing of sleep in humans, and mouse models of these mutations mostly recapitulate the phenotypes. Timing of sleep is heavily influenced by the circadian clock, which has been intensely studied, and we now have a large and growing body of knowledge on how the clock is regulated at the molecular level. On the other hand, our understanding of sleep homeostasis regulation for human lags behind. We reported a mutation in the human DEC2 gene that causes mutation carriers to sleep 6 hours nightly for their entire lives without apparent negative effects. Another mutation in DEC2 was later reported in a single individual who is a short sleeper and resistant to sleep deprivation. Identification of additional genes participating in modulation of human sleep duration provides a unique way to expand our knowledge of genes and pathways critical for human sleep homeostasis regulation.

Noradrenergic signaling in the central nervous system (CNS) has long been known to regulate sleep. The network involving the noradrenergic neurons has been extensively studied, and most of the receptor subtypes have been genetically defined. In contrast to α1 and α2 adrenergic receptors (ARs), relatively little is known about the function of β receptors in the CNS. βARs within the brain were previously suggested to mediate the effect of norepinephrine (NE) for alert waking and rapid eye movement (REM) sleep. Clinically, β-blockers are widely used and can be associated with difficulty falling asleep and staying asleep, possibly due to reduced production and release of melatonin.

We report here a rare mutation in the β1AR gene (ADRB1) found in humans with natural short sleep. Engineering the human mutation into mice resulted in a sleep phenotype similar to that seen in familial natural short sleepers. We show that β1AR is expressed at high levels in the dorsal pons (DP). Neuronal activity measured by calcium imaging in this region demonstrated that ADRB1+ neurons in DP are wake and REM sleep active. Manipulating the activity of these ADRB1+ neurons changes sleep/wake patterns. Also, the activity of these neurons was altered in mice harboring the mutation. Together, these results not only support the causative role of this ADRB1 mutation in the human subjects but also provide a mechanism for investigating noradrenaline and β1AR in sleep regulation at the circuit level.


Reviewing the Aging of Lymphatic Vessels

The lymphatic system a part of the broader circulatory system and has many similarities to the cardiovascular system of blood vessels. The lymphatic system is also a network of vessels, transporting various necessary cells and substances, and subject to processes of aging that degrade function and thereby cause issues. While circulation of fluid is an important function of the lymphatic system, and conditions such as lymphedema arise when it runs awry, the role of lymphatic vessels in the function of the immune system is arguably far more vital.

Immune cells must be able to rapidly travel the body and locally coordinate with one another in order to mount an effective immune response. The lymphatic system links repositories of immune cells, such as those of the spleen and thymus with tissues throughout the body. Lymphatic vessels also link the numerous lymph nodes of the body, where immune cells gather to secrete and accept signals necessary to the correct function of the immune response.

With aging, lymph nodes in particular degenerate and become fibrotic, making it ever harder for immune cells to mount an acceptable defense against pathogens and cancers. The presence of senescent cells and the chronic inflammation they produce is thought to be important in this process, but it is likely one of a number of contributing factors. Further, lymphatic vessels suffer problems arising from loss of control over permeability, regarding what can pass through the vessel walls, as well as many of the same issues with stiffening that are seen in aged blood vessels. This latter problem results from processes such as cross-linking that reduces elasticity by restricting the motion of the complex molecules making up the extracellular matrix, and dysfunction of the smooth muscle tissue responsible for contraction and dilation. The latter degeneration is also in part a consequence of senescent cells and chronic inflammation, but mitochondrial dysfunction is also implicated - as demonstrated by the ability of NAD+ enhancement to improve matters in older patients.

Pathophysiology of aged lymphatic vessels

The aging process induces changes in structure and function of lymphatic networks. Lymphatic-related diseases are prevalent in elderly, such as lymphedema. In 1960s, the specific "varicose bulges" in muscular lymphatic vessels were observed and this bulges were increased with age. Muscle cell atrophy, elastic elements destruction, and aneurysm-like formations were also found in aged lymphatic vessels. Aging associated alterations in lymphatic contractility decrease pump efficiency which result in excessive retention of tissue fluid within interstitial spaces.

Reduced responsiveness to inflammatory stimuli in aged lymphatic vessels decreases the normal capacity to react against foreign organisms. The occurrence of high permeability is caused by the loss of glycocalyx and the dysfunction of junctional proteins. In addition, increased caspase-3 activity, the dissociation of the VE-cadherin/catenin complex and the low expression of actin cytoskeleton that occur in aged blood vessels may also be seen in aged lymphatic vessels.

The lymphatic endothelial cell surface is covered by the glycocalyx layer on the lumen side. The glycocalyx functions as a barrier between lymphatic fluid and the endothelium to prevent immune cells and pathogens from adhering to the endothelium. A significant loss of glycocalyx with a reduction in thickness and destruction in continuity occurs in lymphatic endothelial membranes from aged rat. This observation was in contrast with the intact, continuous layer covering cell membranes from adult lymphatic vessels. The global proteomic analysis of ultrastructural changes of glycocalyx composition also demonstrated a dramatic difference between the adult and aged groups. The thin glycocalyx layer is impaired in its ability to limit certain pathogens from adhering to the endothelial cell membrane and becomes hyperpermeable in the lymphatic vessels from aged rats. Thus in aged lymphatic vessels, pathogens could escape more easily from the collectors into surrounding tissue, along with an increased leakage of lymph fluid and immune cells.

The effect of aging-related hyperpermeability is also observed in blood vessels. Adherens junctions consisting of vascular endothelial cadherin (VE-cadherin) and β-catenin maintain intercellular permeability in both blood vessels and lymphatic vessels. β-catenin, is an intracellular protein that links cadherin with the actin cytoskeleton. Studies have found that aging process may affect all of the adherens junctional proteins. First, global proteomic profiling of the lymphatic vessels from aged rats revealed a significant decrease in cadherins. The downregulation of cadherins expression results in a decreased number of adherens junction complexes. In contrast, β-catenin is a key regulator of barrier integrity and a known substrate for caspase 3, which is an effector caspase in the apoptotic signaling pathway.

Recent research found that increased activity of the intrinsic apoptotic signaling pathway in aged vessels leads to high expression of proapoptotic members (Bak, Bax). Caspase 3 is activated by Bak and mediates barrier dysfunction through the disruption of β-catenin. This series of reactions eventually causes dissociation of the VE-cadherin/β-catenin complex and results in vascular hyperpermeability.

In addition to adherens junctions, tight junctions are an equally important determinant of vascular permeability of blood vessels and lymphatic vessels. As part of the tight junction, occludin and claudin-5 showed significantly low expression level in senescent endothelial cells. We hypothesize that the mechanism of intercellular hyperpermeability caused by the disruption of endothelial cell-cell junctions in aged blood vessels may also exist in aged lymphatic collectors. Further investigations are needed to delineate the detailed mechanisms related to impaired barrier function in aged lymphatic vessels.

Quantifying the Correlation Between Poverty and Faster Pace of Aging

It is well known that wealth correlates with greater life expectancy and related measures such as improved health in later life. The question has always been why this is the case. Wealth correlates with a range of other factors such as education, intelligence, and so forth, all of which can be reasonably expected to influence health via lifestyle choices. In the case of intelligence, there is also some evidence to suggest that more intelligent people are also more physically robust, but the mass of evidence of genetics and longevity also suggests that effect size for genetic variation is small in comparison to that for lifestyle choice.

Genetics, lifestyle and environment are all factors that somehow influence when and how we all age. But the financial situation is also important. Now, researchers have found that four or more years with an income below the relative poverty threshold during adult life make a significant difference as to when the body begins to show signs of ageing.

To learn more about the context, the researchers have tested 5500 middle-aged persons, using various ageing markers: physical capability, cognitive function and inflammatory level. The results were then compared with the participants' income throughout the 22 years leading up to the test. An annual income of 60% below the median income is considered relative poverty. In this way, the researchers found that there is a significant correlation between financial challenges and early ageing.

The participants have been through both physical and cognitive tests, each of which is an expression of general strength and function. Among other things, the researchers measured the participants' grip strength, how many times they could get up from and sit on a chair in 30 seconds, and how high they could jump. The cognitive tests have e.g. been tasks of memorising sequences. The results show, among other things, that the financially challenged group, relative to the comparison group, can get up and sit down two times less per 30 seconds, and that their grip strength is reduced by 1.2 kilos.

In addition, the researchers have measured the inflammatory level of the participants - i.e. an inflammatory state that comes from within and is measured in the blood. A high inflammatory level is a sign that the body is in a state of alert and can likewise be used as a marker for illness and ageing. The study shows that the financially challenged also had higher inflammatory levels.


Microtubule Function and Longevity in Nematodes

Researchers here report on genetic manipulations that alter the function of microtubules in the cells of nematode worms and thereby cause increased longevity. Microtubules help to support cell structure, and act as pathways to allow movement of structures and molecules around the cell. The effect on longevity appear to be mediated via improved or altered function of neurons, leading to alterations in metabolism of a sort already known to influence life span in this species. The degree to which this is relevant to aging in higher organisms remains to be established, but as a general rule one should expect ever smaller effect sizes for this sort of thing as one moves to test in larger and longer-lived species. Short-lived species have lifespans that are very plastic in response to metabolic stress and environmental change, while long-lived species do not.

Microtubules (MTs) play fundamental roles in cellular functions including cell division, cell shape, and intracellular transport. Abnormal MT regulation has been linked to age-related disorders and diseases, and MTs often serve as targets for disease therapies. MT regulation is particularly important for neurons, since their polarized morphologies dictate heavy reliance on MT function for their maintenance. MT regulation is involved on several levels in neuronal function and maintenance of neuronal structure, and also appears to be a general downstream indicator and effector in age-dependent neurodegeneration.

The nervous system modulates lifespan in various species. It detects sensory cues from the environment and internal signals from the animal, and coordinates organismal metabolic homeostasis and energy balance. Different neuron types respond to distinct cues to extend or shorten lifespan through activating distinct neuronal signals and signaling pathways, including the insulin/insulin-like growth factor-1 signaling (IIS) pathway, which plays an evolutionarily conserved role in regulating lifespan. Despite the essential role of MTs in neuronal function and the central role of the nervous system in regulating longevity, MT regulation has not been directly linked to lifespan modulation.

We have recently reported that mutations in MT regulators can affect lifespan in a DAF-16 dependent manner. We found that loss of EFA-6, a protein promotes MT catastrophe, increased mean lifespan of C. elegans and delayed age-associated changes in neuronal integrity, such as axon blebbing and branching as well as mislocalization of synaptic vesicles to dendritic structures within touch sensory neurons. The effects of the loss of EFA-6 opposed those effects seen with the loss of PTL-1, the worm homolog of human Tau protein that stabilizes MT, in previous research as well as experiments conducted in our study.

These results suggest that shifting the balance of neuronal microtubule regulation towards stabilization rather than destabilization without completely abolishing microtubule destabilization processes facilitates the maintenance of neuronal structure and promotes organismal longevity in C. elegans. The efa-6 loss-of-function mutants also maintained greater touch sensitivity and motor function during aging compared to wild-type worms. These differences in neuronal integrity and functional ability were time/aging-dependent with no significant differences between the efa-6 loss-of-function mutants and wild-type worms at day 1 of adulthood but significant differences between the groups by days 9 and 10 of adulthood. In addition, the expression of EFA-6 in neurons, but not in muscle, rescued the phenotypic changes seen in the loss-of-function mutants, suggesting that the regulation of microtubules within neurons is what contributes to the regulation of lifespan.


The Rejuvenation Now Risk-Benefit Analysis of Fisetin as a Senolytic Therapy

The Forever Healthy Foundation's Rejuvenation Now program is engaged in the production of detailed analyses of risk and reward for presently available treatments that may act to slow or reverse aging. I think this is helpful, as a great deal of information exists, but is very scattered, and there is far too much uninformed hype out there. Putting all of the facts together in one place, coupled to a sober assessment of what those facts mean, is a good use of resources. This is particularly true given that senolytic therapies presently exist, and, to the degree to which these treatments successfully clear senescent cells with minimal side-effects, should be expected to produce sizable benefits to health for all old people who use them. Those old people just need to be told, so that they can make an informed choice about their own health.

One of the potential senolytic therapies of interest is a cheap and readily available supplement, fisetin. This is interesting because animal data shows it to be about as good as the dasatinib plus quercetin combination. One might ask how a supplement can be readily available for years, and yet no-one noticed that if you take the whole bottle at once, it significantly reverses inflammatory age-related conditions. Perhaps that is in fact the case, but as the analysis from the Forever Healthy Foundation notes, we just don't know. Human trials are ongoing, and we might expect initial publications from the research groups involved over the next year. This will clarify whether or not fisetin happens to be unusually effective in mice only.

In a sense, either outcome would be surprising. The important parts of the biochemistry of senescent cells, when it comes to the operation of senolytic drugs, are essentially the same between mice and humans. The dasatinib and quercetin combination has been shown to work in humans much as it does in mice when it comes to destroying these cells. Yet fisetin has been readily available and widely used as a supplement for a while, without the sort of attendant murmuring one might expect given the sizable benefits it should produce if it is as senolytic in humans as it is in mice. We shall see what the story is when the clinical trial data for fisetin emerges. Meanwhile, many more self-experimenters are using fisetin than are using the far more proven dasatinib and quercetin combination, given that fisetin is much more easily obtained.

Fisetin Senolytic Therapy Risk-Benefit Analysis

Senolytics are agents that selectively induce apoptosis of senescent cells. Fisetin is a flavonoid polyphenol found in many types of fruits and vegetables that is believed to act as a senolytic in addition to its numerous other known benefits. Although natural senolytics are less potent, compared to the targeted senolytics, they have lower toxicity and are thus, likely to be more readily translatable to clinical medicine. This risk-benefit analysis focuses on the risks and benefits of using fisetin as a senolytic rather than its more common use as a supplement.

There are currently three phase 2 clinical trials underway and the first data is expected to be reported in about a year. The data from the phase 1 trials has not been published. All trials are being conducted by the same investigators at the Mayo clinic using the same treatment protocol. Only two papers directly related to the use of fisetin as a senolytic were identified, neither of which were conducted in humans. The other 5 studies included in the table relate to pharmacokinetics, risk, and lifespan extension.

To the best of our knowledge, there haven't been any studies published on the pharmacokinetics of fisetin in humans. Only one animal study on fisetin has reported any form of toxicity from fisetin use and the authors concluded that the elevations in ALT/AST levels (indications of liver toxicity) were in large part due to the vehicle used to administer the fisetin (DMSO). However, the fisetin + vehicle group showed significantly higher elevations than the vehicle alone group indicating that high doses of fisetin may additionally burden the liver because of its poor bioavailability. At a lower dose (112 mg/kg), fisetin didn't significantly increase apoptosis or lead to liver toxicity. Intermittent dosing and use of a form of fisetin with increased bioavailability are likely to mitigate the risk of liver toxicity.

Fisetin has been shown to decrease senescent cell biomarkers as well as the numbers of senescent cells in a variety of tissues, including ex vivo, human adipose tissue as well as in vivo, in mice. The primary risk mitigation strategy is to wait to commence therapy until clinical trial data has been published that describes the possible benefits and adverse effects. At the current time, the only form and dose that has been tested in phase 1 clinical trials is the so-called "Mayo Protocol". The Mayo Protocol consists of taking 20 mg/kg of oral fisetin on two consecutive days and repeating the same dose, one month later.

A Discussion of Developmental Effects on Aging

To what degree does early life development impact the trajectory of late life aging? Plenty of evidence suggests a connection, much of it from epidemiological studies that, unfortunately, given little insight into possible mechanisms. Of other work, applying reliability theory to aging can only fit the observed mortality data if we are born with a non-zero level of damage. Further, early exposure to cytomegalovirus, a persistent infection that is corrosive of immune function over the long term, may explain links between socioeconomic status in childhood and pace of late life aging. These are two of many studies to provide hypotheses and at least some supporting evidence.

A diverse set of mechanisms could transform episodic or recurrent early exposures in utero, perinatally, and during infancy and early childhood into delayed impacts on adult illness, disability, and mortality. The mechanisms are associated with organ-specific embryo and fetal cell growth and differentiation, epigenetic changes, exposure to and contraction of early childhood diseases and sustained inflammation, and experiences with stressful conditions and environments. Furthermore, a large and influential body of empirical research documents the long-lasting impact of early nutritional status on adult health and mortality. Finally, there is widespread empirical evidence demonstrating that more diffuse exposures, such as poverty and severe deprivation in infancy and early childhood, can also have lasting impacts.

The mechanisms identified above are the focus of various strands of theories with unique histories and distinct disciplinary foundations. Different as they may be, however, they share an important trait as all invoke perturbations during critical periods of the development of a phenotype triggered by insults before conception, during embryonic and fetal life, perinatally, and across early stages of physical and cognitive growth. These early insults may then lead to disruptions in processes of organ growth, differentiation and function, immune response, neurological development, metabolic regulation, and even the formation of adult preferences and behaviors. After variable but usually prolonged latency periods, the disruptions could manifest themselves as increased susceptibility to adult chronic illness.

This shared feature emphasized by multiple variants of developmental effects on aging coexists with important differences that segregate them into distinct classes associated with different outcomes. For example, mechanisms that depend on epigenetic changes, such as methylation of CpG islands caused by nutrient deficiencies, disrupt metabolic function, and are associated with child and adult obesity. Others involve organ damage caused by an immune overresponse to bacteria, as in the case of acute rheumatic heart fever that increases the risk of adult heart valve stenosis. And yet others depend on misfiring of the hypothalamic-pituitary-adrenal (HPA) axis, an adaptation among some mammals to chronic stress, as when early abuse triggers adult depression, aggressiveness, and anxiety. The differences between these mechanisms range over a number of domains including nature and timing of insults, critical and sensitive periods, chronic illnesses, critical ages after which the damage is manifested, and interactions between initial insults and individuals' lifetime exposure to different environments.


Reviewing Changes in Platelet Function in Aging

Platelets are essentially structured chunks of cytoplasm shed by the megakaryocyte cells responsible for producing them, released into the blood stream. They are important in blood clotting and the innate immune response. Inappropriate blood clot formation known as thrombosis occurs more readily in later life, but it is unclear as to the degree to which age-related changes in platelets, versus other systems, are important to this process, or where platelets sit in the complex chains of cause and effect. The open access paper noted here reviews what is known of the aging of platelets and related mechanisms, a topic that is not as well investigated as other aspects of cardiovascular aging.

Platelet count is inversely associated with age. A large study based on the Third National Health and Nutrition Examination Survey including 12,142 American subjects showed a significant decrease of 10 × 10^3 platelets/μL in individuals in the 60-69 year age group as compared with those between the ages of 20-59 years, and of 20 × 10^3 platelets/μL in patients aged over 69 years of age, after adjusting for many covariates such as nutritional deficiencies, medication, inflammatory conditions, autoimmune or viral illnesses, and consumption of alcohol and tobacco. This suggests that the drop in platelet count with age is part of the biological aging process per se and not only due to environmental factors.

One of the most documented changes in platelet function during aging is platelet hyperactivity. Bleeding time decreases significantly in aging, denoting a faster clot formation and indirectly an enhanced platelet activity in the elderly. Furthermore, platelets from older men and women have a greater sensitivity to aggregation induced by classical agonists. Furthermore, β-thromboglobulin and platelet factor 4 (PF4), two proteins secreted from platelets α-granules, are both found at a significantly higher level in plasma of older compared with younger subjects. This is consistent with the hyperaggregability observed in elderly individuals since platelets release their granule content during activation.

The mechanisms of this age-related platelet hyperactivity remain unclear. Researchers have tested the hypothesis that modifications in phosphoinositide turnover, an important signaling mechanism of platelet activation, may be responsible for platelet hyperactivity in aging. They have found that platelet phosphoinositide turnover is enhanced in aging and correlates positively with platelet aggregation and plasma β-thromboglobulin levels. It has also been suggested that there could be a functional or expressional change in platelet α and β-adrenoreceptors, however the reported literature is conflicting.


Senolytic Treatment with Dasatinib and Quercetin Confirmed to Reduce the Burden of Senescent Cells in Human Patients

Setting aside the mice genetically engineered to destroy senescent cells, the combination of dasatinib and quercetin is the oldest of the senolytic treatments used in animal studies. Senolytic therapies are those that selectively destroy senescent cells in old tissues in order to produce rejuvenation, turning back the progression of numerous age-related conditions. Unusually for early stage research, these initial senolytics are actually quite effective, considered in the grand scheme of things. Thus they have moved directly to human trials in some cases. The first data on their ability to produce the same outcomes in humans as in mice emerged this year, and more data will continue to roll out over the next few years as the first trials run and complete. The results reported in today's open access paper provide an important demonstration for those not yet convinced that the animal data is relevant.

Meanwhile, the older members of the self-experimentation community have been using dasatinib, quercetin, and a few other senolytics for a few years now on the strength of the animal data and the whisper network of positive outcomes. Further, groups such as the Age Reversal Network are attempting to build physician networks and support for off-label use of senolytics.

While senescent cells are important in a range of beneficial processes, from cancer suppression, to the Hayflick limit, to wound healing, their presence is temporary in all such cases. Near all are destroyed, either by programmed cell death or by the immune system. Lingering senescent cells, on the other hand, are an entirely different story: they are in fact an important cause of aging and age-related dysfunction. They secrete a potent and inflammatory mix of signals that rouses the immune system to destructive chronic inflammation, degrades surrounding tissue structure and function, and encourages other cells to also become senescent.

The more lingering senescent cells present in the body, the worse the outcome for health, and their numbers steadily and inexorably grow with age. The silver lining here is that senescent cells actively maintain a degraded, aberrant state of metabolism, regeneration, and tissue function. If they are removed, rejuvenation takes place quite rapidly. In some cases, surprising levels of rejuvenation, with features of aging that might have been thought irreversible, and that no existing medicine can much affect, vanishing as the tissue environment becomes less aged and dysfunctional. The world at large will begin to wake up to the true potential here as trials continue, but it remains a tragedy that hundreds of millions of people worldwide could have their quality of life significantly improved overnight, if they only knew. But it isn't happening. Dasatinib and quercetin are both mass produced and cheap, easily obtained, easily used. Too little is being done to bring this treatment to the masses who could benefit.

Mayo researchers demonstrate senescent cell burden is reduced in humans by senolytic drugs

In a small safety and feasibility clinical trial, researchers have demonstrated for the first time that senescent cells can be removed from the body using drugs termed "senolytics". The result was verified not only in analysis of blood but also in changes in skin and fat tissue senescent cell abundance. Senescent cells are malfunctioning cells that accumulate with aging and in organs affected by chronic diseases. Senescent cells can remain in the body and contribute to multiple diseases as well as features of aging, ranging from heart disease to frailty, dementias, osteoporosis, diabetes, and kidney, liver, and lung diseases.

For three days the nine participants received a combination dose of dasatinab and quercetin. Though the drugs cleared the body in a couple of days, effects on reducing senescent cells were evident for at least 11 days. The researchers say this shows the senolytic drug combination significantly decreases senescent cell burden in humans. Senescent cells are characteristic in end-stage kidney failure as well as diabetes-related kidney disease. By removing the cells from mice, researchers had previously found that senolytics alleviate insulin resistance, cell dysfunction, and other processes that cause disease progression and complications. While more research is needed on the impact of senolytics on diseases and disorders of aging, the researchers say the results of occasional dosing reduces risks from having to give drugs continuously.

Senolytics decrease senescent cells in humans: Preliminary report from a clinical trial of Dasatinib plus Quercetin in individuals with diabetic kidney disease

By definition, the target of senolytics is senescent cells, not a molecule or a single biochemical pathway. The first senolytic drugs, Dasatinib (D) and Quercetin (Q), were discovered using a mechanism-based approach instead of the random high-throughput screening usually used for drug discovery. Because senescent cells can take weeks to months to develop and do not divide, and because even eliminating only 30% of senescent cells can be sufficient to alleviate dysfunction in preclinical studies, D + Q is as effective in mice if administered intermittently, for example every 2 weeks to a month, as continuously, even though D and Q have elimination half-lives of only 4 and 11 hours, respectively. This is consistent with the point that, since the target of senolytics is senescent cells, these drugs do not need to be continuously present in the circulation in the same way as drugs whose mechanism of action is to occupy a receptor, modulate an enzyme, or act on a particular biochemical pathway, at least in mice. Intermittently administering D + Q effectively circumvents any potential off-target effects due to continuous receptor occupancy or modulation of an enzyme or biochemical pathway.

Based on the many promising studies of D + Q in mice, the experience gained from the use of D in humans for over 20 years, and the fact that Q is a natural product present in many foods such as apples, we initiated clinical trials of these agents. The first-in-human clinical trial of senolytics was a brief course of D + Q for patients with idiopathic pulmonary fibrosis, which resulted in statistically significant improvements in physical function in 14 subjects with this relentlessly progressive, debilitating, and ultimately fatal cellular senescence-driven disease. Although alleviation of this cellular senescence-related phenotype was demonstrated in that pioneering trial in tandem with trends for decreased senescence-associated secretory phenotype (SASP) factors, and others found decreased SASP factors in a trial of continuous D administration in the skin of subjects with systemic sclerosis, so far, there has been no direct demonstration of senescent cell clearance by senolytic drugs in peer-reviewed published human clinical trials.

To test whether intermittent D + Q is effective in targeting senescent cells in humans, we administered a single 3 day course of oral D + Q and assayed senescent cell abundance 11 days after the last dose in subjects with diabetic kidney disease, the most common cause of end-stage kidney failure and which is characterized by increased senescent cell burden. We found D + Q alleviates insulin resistance, proteinuria, and renal podocyte dysfunction caused by high fat diet-induced or genetic obesity in mice. We also found that even Q alone can prevent high fat diet-induced increases in markers of senescence, renal fibrosis, decreases in renal oxygenation, and increased creatinine in mice, although Q alone did not prevent insulin resistance. Diabetes and chronic kidney disease (CKD) in humans therefore represent conditions that may benefit from D + Q therapy-induced alleviation of tissue dysfunction and disease progression, which is being tested as the clinical trial reported here continues. In this interim report of findings from that trial, we found the single brief course of D + Q attenuated adipose tissue and skin senescent cell burden, decreased resulting adipose tissue macrophage accumulation, enhanced adipocyte progenitor replicative potential, and reduced key circulating SASP factors.

Chimeric Antigen Receptor T Cells as a Treatment for Fibrosis

Chimeric antigen receptor (CAR) T cell therapies are used to treat cancer, engineering T cells to be more aggressive towards cancer cells. The approach has proven quite effective in comparison to past treatments for a number of cancer types. In principle this CAR-T immunotherapy can be used to target any cell population that has distinct surface markers, not just cancer cells. Here, researchers demonstrate the ability to destroy the fibroblasts responsible for generating fibrosis in the aging heart. Fibrosis is a form of dysregulated tissue maintenance, in which cells build up scar-like deposits of collagen that degrade tissue structure and function. It is interesting to compare this with work on clearing senescent cells in heart tissue, which also reverses fibrosis. Senescence is clearly one of the factors driving fibroblasts to become overactive, most likely via the inflammatory, pro-growth signaling produced by senescent cells, rather than via fibroblasts becoming senescent in large numbers.

Heart disease is the leading cause of death in the United States, and excessive cardiac fibrosis is an important factor in the progression of many forms of heart disease. It develops after chronic inflammation or cardiac injury, when cardiac fibroblasts - cells that play an important role in the structure of the myocardium, the muscular middle layer of the heart's wall - become activated and begin to remodel the myocardium via extracellular matrix deposition. Research has shown that the removal of activated cardiac fibroblasts can reduce heart stiffness, making it easier for the ventricles to relax. However, there are no therapies that directly target excessive fibrosis, and very few interventions have shown the ability to improve heart function and outcomes among patients with impaired cardiac compliance.

As a first step, researchers launched a genetic proof-of-concept experiment using mice that can express an artificial antigen (OVA) on cardiac fibroblasts. The mice were treated with agents to model hypertensive heart disease, a condition associated with left ventricular hypertrophy (enlargement or thickening of the heart walls), systolic and diastolic dysfunction (pumping of blood in and out of the heart), and widespread cardiac fibrosis. To selectively target the OVA proteins expressing cardiac fibroblasts, the team treated one cohort of mice with engineered CD8+ T cells that express a T-cell receptor against the OVA peptide. At the four-week mark, the mice who were treated with the reengineered cells had significantly less cardiac fibrosis, whereas the mice in the control groups still had widespread fibrosis.

After establishing the feasibility of this approach, researchers sought to identify a protein specifically expressed by activated fibroblasts that they could program the genetically modified T cells to recognize and attack. Using an RNA sequence database, the team analyzed gene expression data of patients with heart disease and identified the target: fibroblast activation protein (FAP), a cell surface glycoprotein. Researchers then transferred engineered FAP CAR T-cells into mice at the one and two week marks, aiming to target and deplete FAP-expressing cardiac fibroblasts. Within a month, researchers saw a significant reduction of cardiac fibrosis in the mice that were treated with the engineered cells, as well as improvements in diastolic and systolic function.


A Rapid Process for Senolytic Drug Discovery

In Silico Medicine specializes in the application of computational methods to speed up the process of screening small molecule drugs, while reducing the costs, an advance in infrastructure technology that is very much in favor these days. Most of the large entities in medical development still proceed exactly has they have done for decades in the matter of developing new therapies: find a molecular target, then find a small molecule that influences that target, then iterate over variations to try to increase efficacy and reduce side-effects. Thus numerous groups work in this part of the field, trying to cut presently sizable costs and improve the presently poor odds of success. In this paper, the In Silico Medicine team demonstrates that they can very rapidly identify candidate small molecule senolytic drugs, capable of clearing the senescent cells that contribute to aging and age-related disease.

A team of researchers has succeeded in using Artificial Intelligence to design, synthesize and validate a novel drug candidate in just 46 days, compared to the typical 2-3 years required using the standard hit to lead (H2L) approach used by the majority of pharma corporations.

By using a combination of Generative Adversarial Networks (GANs) and Reinforcement Learning (RL), the team of researchers behind this study (documented in a paper published this month) have succeeded in validating the real power that AI has to expedite timelines in drug discovery and development, and to transform the entire process of bringing new drugs to market from a random process rife with dead ends and wrong turns to an intelligent, focused and directed process, that takes into account the specific molecular properties of a given disease target into account from the very first step.

Researchers have long advocated for the extreme potentials that AI has in terms of making the process of discovering and validating new drugs a faster and more efficient process, especially as it pertains to aging and longevity research and the development of drugs capable of extending human healthspan and compressing the incidence of age-related disease into the last few years of life. While this is the newest in a long line of steps and accomplishments aiming to turn the theoretical potentials of AI for longevity research into practice, it is also the largest step made thus far, and goes a very long way in terms of proving that potential via hard science.


Arguing for Extracellular Vesicles to Mediate Beneficial Effects of Parabiosis

Cells communicate with one another constantly, and a large portion of that communication is not carried by individual secreted molecules, though there are certainly a lot of those, but rather takes the form of small membrane-bound packages of diverse molecules known as extracellular vesicles. Cells generate and secrete extracellular vesicles of various sizes, and other cells ingest them. Two important areas of active research into cell signaling are the way in which young tissue can restore the function of old cells, and the way in which senescent cells change the activity of surrounding cells for the worse. In both cases, extracellular vesicles are important in this process of communication and influence.

There is a substantial faction in the research community focused on potentially beneficial effects that derive from young blood, emerging from the study of heterochronic parabiosis in which the circulatory systems of a young and old mouse are linked. The old mouse benefits and shows some signs of reversal of the consequences of aging, the young mouse exhibits accelerated signs of aging. Is this in fact due to beneficial signals in young blood? There is good evidence that strongly supports the case that benefits result from a dilution of harmful factors in old blood, and that beneficial factors in young blood are not important. Nonetheless, there is further independent evidence in which factors or extracellular vesicles derived from young blood have been used to produce benefits in old mice. There are also a number of failures to show meaningful benefits from blood or plasma transfusion, in mice and humans. It is an interesting field, in which conflicting evidence abounds.

Extracellular vesicles circulating in young organisms promote healthy longevity

In the late 1950s, parabiosis experiments provided some scientific consistency to these beliefs. Indeed, a shared circulatory system was sufficient to increase bone weight and density of old mice when joined to younger ones. The same experimental design was applied to demonstrate a lifespan-enhancing effect of young blood. Many years later, elegant reports demonstrated a rejuvenation-promoting effect of young blood in a wide variety of cells and tissues, e.g. stem cells, muscle, brain, and the heart. However, the pursuit of the circulating factors responsible for such effects did not achieve the same success. In fact, the suggested pro-regeneration role of growth differentiation factor 11, a member of the TGFβ superfamily, has been questioned.

Extracellular vesicles (EVs) are membrane-coated nanoparticles actively released by almost all cell types. Increasing evidence indicates that both are able to shuttle and deliver functional proteins and nucleic acids in a paracrine and systemic manner. Blood contains a heterogeneous mixture of EVs of different origins, which are currently being characterized for therapeutic and diagnostic purposes. The effects of EVs are now attracting intense interest also in the context of ageing and age-related diseases (ARDs).

In particular, senescent cells (SCs) are emerging as major drivers of ageing and key contributors to inflammaging, the age-associated pro-inflammatory drift that promotes the development of ARDs. Recent evidence suggests that EVs are also central constituents of the SCs secretome. In particular, SCs secrete an increased amount of EVs, excreting pro-inflammatory DNA and possibly spreading pro-ageing signals. Conversely, a seminal paper suggests that a 4-month injection of small EVs derived from hypothalamic neural stem cells and rich in specific miRNAs into the hypothalamic third ventricle is sufficient to ameliorate some age-associated detrimental outcomes in C57BL/6 mice, including hypothalamic inflammation and the drop in physical activity.

These and other observations prompted the hypothesis that EVs are central mediators of the circulating communicosome fostering inflammaging. In that framework, we hypothesized that the chronic administration of EVs purified from a young healthy mouse to an old one should ameliorate some age-associated phenotypes. This experimental approach appeared to be enough feasible and robust to demonstrate a tangible role of EVs in the ageing process. Researchers have now shown a clear pro-longevity role for EVs isolated from young mouse plasma. Indeed, they injected EVs isolated from 4-to-12-month-old mice into 26-month-old female mice once a week until sacrifice and observed an increase of 10.2% and of 15.8% in median and maximal lifespan, respectively, in mice receiving the treatment vs. vehicle-treated mice of the same age.

Controlling Hypertension Slows Cognitive Decline

The study here shows that given a population of individuals with hypertension, those who manage to control their high blood pressure go on to suffer lesser degrees of cognitive decline. Numerous mechanisms may link hypertension to structural damage in the brain: degeneration of the blood-brain barrier, allowing inappropriate molecules and cells into the brain, leading to neuroinflammation and other effects; rupture of capillaries causing microbleeds, effectively tiny strokes; outright pressure damage in tissue very close to small vessels that directly harms brain cells; and so forth. This damage adds up, but note that it is a set of physical issues that stem from increased pressure rather than the biochemistry that causes that increased pressure. Therefore these downstream issues can be suppressed by any method that reduces blood pressure consistently, even though that will leave the underlying damaged biochemistry to continue to cause other issues.

High blood pressure appears to accelerate cognitive decline among middle-aged and older adults, but treating high blood pressure may slow this down, according to a preliminary study. According to the American Heart Association's 2017 Hypertension Guidelines, high blood pressure affects approximately 80 million U.S. adults and one billion people globally. Moreover, the relationship between brain health and high blood pressure is a growing interest as researchers examine how elevated blood pressure affects the brain's blood vessels, which in turn, may impact memory, language, and thinking skills.

In this observational study, the researchers analyzed data collected on nearly 11,000 adults from the China Health and Retirement Longitudinal Study (CHARLS) between 2011-2015, to assess how high blood pressure and its treatment may influence cognitive decline. High blood pressure was defined as having a systolic blood pressure of 140 mmHg or higher and a diastolic blood pressure of 90 mmHg or higher, and/or taking antihypertensive treatment. According to guidelines of the American Heart Association, high blood pressure is defined as 130 mmHg or higher or a diastolic reading of 80 mmH or higher.

Researchers interviewed study participants at home about their high blood pressure treatment, education level, and noted if they lived in a rural or urban environment. They were also asked to perform cognitive tests, such as immediately recalling words as part of a memory quiz. Among the study's findings: (a) Overall cognition scores declined over the four-year study; (b) Participants ages 55 and older who had high blood pressure showed a more rapid rate of cognitive decline compared with participants who were being treated for high blood pressure and those who did not have high blood pressure; (c) The rate of cognitive decline was similar between those taking high blood pressure treatment and those who did not have high blood pressure.


Lipid Turnover in Fat Tissue Decreases with Age

Researchers here show that lipid turnover in fat tissue decreases with age, and suggest that this mechanism explains some fraction of the tendency to gain weight with age. Everyone of a certain age recognizes that it takes ever more effort to evade or get rid of excess fat tissue. It remains an open question as to which underlying mechanisms cause this change in lipid turnover, though given progress in rejuvenation research we are at the point of being able to test hypotheses such as chronic inflammation resulting from senescent cells, or mitochondrial dysfunction. We shall see what new data on this topic emerges in the years ahead.

Scientists studied the fat cells in 54 men and women over an average period of 13 years. In that time, all subjects, regardless of whether they gained or lost weight, showed decreases in lipid turnover in the fat tissue, that is the rate at which lipid (or fat) in the fat cells is removed and stored. Those who didn't compensate for that by eating less calories gained weight by an average of 20 percent, according to the study.

The researchers also examined lipid turnover in 41 women who underwent bariatric surgery and how the lipid turnover rate affected their ability to keep the weight off four to seven years after surgery. The result showed that only those who had a low rate before the surgery managed to increase their lipid turnover and maintain their weight loss. The researchers believe these people may have had more room to increase their lipid turnover than those who already had a high-level pre-surgery.

"The results indicate for the first time that processes in our fat tissue regulate changes in body weight during ageing in a way that is independent of other factors. This could open up new ways to treat obesity." Prior studies have shown that one way to speed up the lipid turnover in the fat tissue is to exercise more. This new research supports that notion and further indicates that the long-term result of weight-loss surgery would improve if combined with increased physical activity.


Matthew O'Connor Presenting on Underdog Pharmaceuticals at Undoing Aging 2019

Here Matthew O'Connor of the SENS Research Foundation talks about the research that led to founding of Underdog Pharmaceuticals, a biotech startup incubated by the foundation to commercialize a means of targeting 7-ketocholesterol in atherosclerosis and other conditions. Oxidized cholesterols, and largely 7-ketocholesterol, are the primary cause of dysfunction in the macrophage cells normally responsible for preventing the build up of fatty plaques in blood vessel walls. That dysfunction is the cause of atherosclerosis, and the fact that the presence of oxidized cholesterols increases with age is one of the reasons why atherosclerosis is an age-related disease, and why young people don't exhibit the plaques that narrow and weaken blood vessels.

A sufficiently effective way of selectively clearing 7-ketocholesterol from the body should go a long way towards preventing and reversing atherosclerosis - and possibly other conditions as well. As noted here, there is evidence for 7-ketocholesterol to accumulate in other tissues and contribute to age-related conditions in other ways. The particular approach taken by the SENS Research Foundation scientists is to find a non-toxic molecule that selectively binds to the toxic molecule that one would like to remove, 7-ketocholesterol in this case, and deliver it to the body in volume. The bound molecules are then processed and excreted in the normal way. It will be interesting to see how the Underdog project progresses in the years ahead.

Matthew O´Connor presenting at Undoing Aging 2019

Thank you everybody. It is a real honor and a pleasure to be here today, speaking in a last minute slot. Don't volunteer to take over to speak for someone who didn't show up, because then you have to stay up all night, working on your slides. This slide is the SENS team from this last summer, a combination of the MitoSENS team and the team working on 7-ketocholesterol that Aubrey de Grey was just referring to, that we're calling the Underdog team. You can see me as the chief Underdog there.

I want to just spend a minute, Aubrey had mentioned that this is the tenth anniversary of SENS Research Foundation, and it is my 9th year with SENS Research Foundation. It has been a privilege to have started so early, to help build the lab, and I wish that I could show a time lapse photography of where it started and where it has gone, and also to be involved with some of these amazing interns. So many of these projects, including this one, are very intern driven. Regarding the MitoSENS team, people may not realize that all the progress Aubrey was talking about, publishing papers all of a sudden, didn't happen until after we hired Amutha, so you can see why that project got taken away from me and given to her. She is just a phenomenal mitochondrial biologist.

So this project that I'm about to tell you about involves a story about 7-ketocholesterol. I hope that a lot of you have heard about it. It is kind of one of the classic bad guy molecules that Aubrey has been talking about for a long time. My history with it goes back even further than SENS Research Foundation, as the foundation and Methuselah Foundation before it have been funding work on trying to get rid of this really nasty molecule 7-ketocholesterol for at least ten years, with work that we've funded in various places. I actually heard Aubrey give a talk about this, one of the best talks I've ever seen, at Rice University something like 15 years ago when I was in graduate school. So I've been thinking about it ever since then.

This project kind of started out as some ideas about how to think about this problem and how to get rid of this nasty molecule a different way. It started out as something that we were sort of dabbling in, and graduated from being my 20% project to something that is all-consuming now. On this slide, you can see causes of death worldwide, which probably looks familiar to you many of you. As Aubrey was just saying, atherosclerosis is the world's biggest killer. If you risk-adjust all of these diseases for what their underlying cause is, atherosclerosis is believed by world health organizations to kill about 44% of everybody. This molecule, 7-ketocholesterol, an oxidized form of cholesterol, is thought to be one of the earliest stages leading to atherosclerosis. But not everyone simplistically believes in that model; the classic model is that you eat too many hamburgers and you get too much cholesterol in your bloodstream, and that just sort of stochastically builds up, and eventually you get plaques, and eventually they rupture and you have heart attacks and strokes, and you die.

However 7-ketocholesterol is many, many, many times more toxic than LDL cholesterol is - so I call it the really bad cholesterol. It is by far the most common product of the reaction between a free radical and cholesterol, and so more often than not you get this stable 7-ketocholesterol which is extremely toxic. It has no useful purpose in your body. It can accumulate in the lysosomes of macrophages and can be an early step in the progression towards becoming a foam cell. Foam cells build up as a layer in atherosclerotic plaques, and 7-ketocholesterol is found inside them, as well as in the necrotic core of the plaque.

Let me change gears now and reveal the class of drug, the class of molecules, that we have been playing around with for the last few years. They are called cyclodextrins. You may or may not have heard of them, but they are a huge industry, and they have a huge variety of applications. The medical applications, despite the fact that cyclodextrins have been studied and applied for many decades, are only just starting to be realized. They come in three basic flavors, alpha, beta, and gamma, which are three different sizes, and they have six, seven, or eight different sugar rings that they are made out of. There are different forms of them, probably thousands of different ones that have been invented. They are extremely customizable and modifiable. Any one of these hydroxyl groups you can stick just about anything you want on it, doing synthetic chemistry.

The slide here shows just a few examples of common cyclodextrins that are used for various industrial purposes. Medically, they are mostly now only used as excipients, meaning as carrier molecules for small hydrophobic drugs. They are used in food: alpha-cyclodextrin is approved in the European Union as a bulk fiber supplement, so maybe you ate some of it this morning. There are versions of these that are extremely low toxicity household items, like Febreze. People can use cyclodextrins, use different formulations of them mixed with other guest molecules that stick into the cyclodextrin cavity, to engineer all kinds of materials such as self-healing gels. They look like jello, and you cut it in half and put it back together and there is no seam any more. Somebody in Japan built a car out of cyclodextrins, and there is a German scientist who is making self-healing paint for cars.

Now let me summarize a bit the history of using cyclodextrins themselves as the active component of drugs. That is what we're trying to do here, to engineer them to be drugs to target 7-ketocholesterol directly. The history here goes back to the 1990s, where this Australian group had a lot of foresight; they already knew that 7-ketocholesterol was a really toxic atherogenic molecule back then, this isn't a new discovery. There has been tons of evidence for that for decades. Cyclodextrins were just starting to be explored in the 80s and 90s as cholesterol binding drugs; different versions of them bind cholesterol well. So they went looking for a modified cyclodextrin that can specifically bind 7-ketocholesterol with a hypothesis, and they found hydroxpropyl-beta-cyclodextrin, which I will tell you about. After they published a bunch of papers, however, they abandoned it and never went into any animal studies.

However, there was a group in Texas that seems to have picked up on this idea, and there was an orphan disease called Niemann-Pick type C, which is a lysosomal storage disease, that hyperaccumulates 7-ketocholesterol. These patients, almost always children, are very sick and die very young. There are good mouse and cat models for this disease, and if you dose them with very high doses of hydroxpropyl-beta-cyclodextrin, you can rescue the small animals. People have started to look at this for atherosclerosis because hydroxpropyl-beta-cyclodextrin is so safe, but there is some debate as to whether you are targeting 7-ketocholesterol, and I'll present some evidence as to why I'm strongly in favor of one hypothesis over the other. For the Niemann-Pick studies, it is going into clinical trials, it is entering phase II, there is a lot of funding going into this now. Presumably because they've got their eyes on atherosclerosis rather than just Niemann-Pick, which is an extraordinarily rare disease.

This slide shows some older data on cyclodextrin, and this came from the Australians. They are soluablizing 7-ketocholesterol, and here is the effect that it has on cholesterol, which is to say nothing, while it does a great job soluablizing 7-ketocholesterol. I'm going to talk a lot about this assay, so if you don't understand it, hold tight and I'll explain it in more detail. 7-ketocholesterol is very toxic, so with increasing doses you kill cells in culture and this was work we funded at Rice University, kind of as a scientific control for the experiments that they were doing. They were playing with cyclodextrin; as I said, it has a lot of different functions. They were using it as a carrier molecule, and found that it was working better than anything else that they were using, while we were working on the earlier LysoSENS enzymatic process to rescue the cells from 7-ketocholesterol toxicity. Then more recently, work in that same lab led to a paper and a patent on the idea of using that same cyclodextrin to prevent and reverse lipofuscin from forming in cells.

So I'll leave that there as history and show you this happy and sad video of cats with Neimann-Pick disease. All three of these cats have this disease and their phenotype is pretty similar to that of the humans. It is a devastating disease. All of these cats have it, one of these cats has been treated with hydroxpropyl-beta-cyclodextrin at a very high dose. Apparently this video is famous in the FDA for how you get something fast tracked into humans by showing a heart-tugging video like this. Because it clearly is working very dramatically to help these cats.

This slide shows the assay that we use. It is a really simplistic assay to screen through many different compounds, the many different cyclodextrins, many different modifications to cyclodextrins that we've made. It is a simple turbidity assay that we've automated. If you dump most sterols that are not water soluable into an aqueous solution, they get cloudy. Then if you managed to add something to the solution that can soluablize the sterols, then the solution turns clear. That is an indication that they are binding to your target.

So we've automated it, you run many of these plates, read them in a plate reader, and you get data that looks like this next slide. I'm just reporting the percent turbidity, so start at 100% and then go down, or in some cases it becomes more cloudy. So these are some cyclodextrins that have been studied for Neimann-Pick disease, as I keep talking about, hydroxpropyl-beta-cyclodextrin is one of our favorites. It doesn't bind cholesterol, even at ridiculously high concentrations. With 7-ketocholesterol it has nice specificity. There's another one, sulphobutyl, that has also been tested somewhat in animal models for Neimann-Pick disease but hasn't really gone further than that, and doesn't seem to be as effective as hydroxpropyl-beta-cyclodextrin.

The safety profile for some cyclodextrins such as hydroxpropyl-beta-cyclodextrin is just phenomenal. It is much less toxic than aspirin, or something like that. So you can dose humans or animals with grams of it and they are fine. As you can see, hydroxpropyl-gamma-cyclodextrin, a bigger one, doesn't do anything in the assays.

We've checked many different cyclodextrins and run them through our screening process. This slide shows a bunch more from the catalogs. Some of them are better and some of them are worse. The point of showing this to you is to show how we gathered a ton of data about which cyclodextrins were interacting with which targets in which ways, and I deleted a whole bunch of data because I was practicing this this morning, and I had too much in the presentation. But we also screened a bunch of other targets, other sterols that you can order from the Sigma catalog. That helps us look at off-target effects.

We can also do it computationally. On this slide you see the former intern that Aubrey was bragging about before. She had the idea when she was an intern - we were already working on this project, and making some progress, and she said well why don't you just model them, you can learn so much about them. She said I'll figure it out. So now she's one of the world's experts in modeling cyclodextrins. Which is a very niche field. Only a few people in the world know how to do this.

What you see here is a molecular dynamic simulation of just a basic beta-cyclodextrin. We've done hundreds of different simulations on different tweaks and different cyclodextrins, mostly with just cholesterol and 7-ketocholesterol, trying to optimize selectivity binding. Also to optimize the affinity. So beta-cyclodextrin, just the core molecule, is known as a good cholesterol binding molecule, but we can learn additional things here. If you stick it in this way, both cyclodextrin and cholesterol are asymmetrical molecules and if you start with it the wrong way, it will go in the way that it prefers. It seems kind of nitty-gritty to talk about, but that kind of information is what helped us figure out all the different subtle ways in which cyclodextrins are binding their targets.

Now on this slide is a model of hydroxpropyl-beta-cyclodextrin binding 7-ketocholesterol extremely tightly and with specificity. To really get the lowdown on this, and this is all unpublished data, we'll have a publication coming out soon, that we're furiously writing now. Go see the posters at this conference, and grill me on this, because the author is brilliant, she's great at explaining it. So we started optimizing cyclodextrins, making little tweaks to them, and came up with some tricks on how to improve the affinity for them, starting out with hundreds of these models. This slide shows the kind of data you'll get from it, the geometry of how they are interacting, how closely in space they are interacting. Then the information, that I think is the most dramatic, about the affinity.

So when you find one that is actually going to grab on super-tightly, then you massively increase the free energy of interaction, or decrease it. You can see that this also corresponds with super-close, tight, and stable interaction between the two molecules. Those kinds of simulations are extremely high resolution. We do them for a whole microsecond, which is an eternity in terms of nanosecond resolution simulations of molecules. The chief way to do lots of simulations is to do molecular docking, and so using this method - this slide is, I think, 28 different simulations that are done quickly, doing just small little tweaks to a particular family of cyclodextrins. We look for areas such as here where you seem to get separation between cholesterol and 7-ketocholesterol.

That is what led us to the step shown on this slide, which is that we synthesized some new cyclodextrins and checked to see if they could increase their affinity and maintain specificity for 7-ketocholesterol. Up at the top here you have hydroxpropyl-beta-cyclodextrin, which doesn't bind cholesterol, it binds 7-ketocholesterol a little bit. However, note the change in scale down here, we're using lower dosing ranges. The modifications that we're making to these that I'm showing you here today, they all work phenomenally well to massively increase the affinity for our target 7-ketocholesterol. However, all of them also increase their affinity for cholesterol. You probably can't see all of them in this slide, but some of them are maintaining better specificity than others, and those are the ones we're most excited about.

So there are a couple of different families of new cyclodextrins that we've invented that have extremely high affinity for 7-ketocholesterol. One in particular that caught our eye that we're really excited about - again, hydroxpropyl-beta-cyclodextrin up here at the top of the slide, some nice specificity for 7-ketocholesterol. Down here, one of the new cyclodextrins that we made has an extremely high affinity for 7-ketocholesterol, and good specificity.

Like I was saying before, these are exciting molecules to work on because they are really safe, the different versions are edible, breathable, or injectable, as in happening in the Neimann-Pick trials. A classic safety test before going in vivo is to collect some blood from whatever hapless CEO or intern happens to be wandering down the wrong time, and then treat their blood with something, and if it lyses it, then it is killing their blood cells, and if it stays clear then it is not. All of the new cyclodextrins that we've made seem to be non-toxic in the pharmacological range, and as you go above that you get some variation. For the one we're most excited about, that had the highest specificity for 7-ketocholesterol, we couldn't find a dose at which we would kill any blood cells.

I'm going to try to make the case that animal models for atherosclerosis are useless, and that we should skip straight to humans. My argument is that mice, rodents, don't get atherosclerosis naturally, and when you do give it to them by knocking out their ability to metabolize cholesterol, they are just not able to take up cholesterol, to clear it, so that it just builds up into artificial plaques. We don't think that is a good model. So once again we're working in humans, we're stealing their blood, and then treating blood with the drug in concentrations that we think are realistic and for time periods that we think are realistic. We know a lot - so much work has been done on safety for cyclodextrins over the years. We know a lot about how quickly it is cleared from circulation in different animal systems and even humans.

Then what we're doing is instead of trying to measure serum 7-ketocholesterol levels, which basically don't exist, as 7-ketocholesterol isn't transported in HDL or LDL, and that is part of what makes 7-ketocholesterol so toxic, as it can't be transported out of cells. We're measuring our ability to release 7-ketocholesterol into the serum, and measuring it by mass spectrometry. The early data on our new cyclodextrins is looking good. In this slide here is hydroxpropyl-beta-cyclodextrin that can remove some 7-ketocholesterol from human blood cells, and the first new cyclodextrin that we made can do a lot more, a lot better, and with blood from multiple donors.

So to recap, there are some big players in this area that are excited about being able to treat an orphan disease like Neimann-Pick disease. They probably have their eyes on going after bigger indications like heart disease, but they think that they are treating cholesterol, which I think is crazy. I think that they are actually treating 7-ketocholesterol, and that they are having the success that they are having because of this. However our drug blows it away in terms of affinity for the target by something like tenfold.

Beyond atherosclerosis, 7-ketocholesterol is implicated in a number of diseases, as shown on this slide. It is one of those bad guys that accumulates in different tissues with age, and we don't even know yet everything that it is implicated in. Just as for senescent cells now that people are finding ways to kill them, all of a sudden you are finding aspects of aging that are being reversed when you kill senescent cells, and I predict that someday we'll see the same thing with 7-ketocholesterol. However, atherosclerosis and heart failure I think are great indications. Of course familial hypercholesterolemia is just an exaggerated way to get atherosclerosis. There is Neimann Pick disease, and we think are drug would work better than the ones that are out there now.

I don't want to try to claim that 7-ketocholesterol causes everything that has ever made everyone sick, but it does accumulate in macular degeneration and some cells in Alzheimer's disease. Our tools that we've developed to make new cyclodextrins, to test them, to model them, I think that this is a great platform. There are other toxic oxysterols that we could be going after that we haven't starting working on yet, but are good targets for this kind of technology. Basically any small hydrophobic molecule that is bioaccumulating is a potential target. So the space in this area looks crowded because there are tens of thousands of patents on cyclodextrins, however when you get down into using cyclodextrins as drugs themselves, then you are down into single digits, like four or five patents that are out there. So we think that we have pretty strong data and protections that will get there.

Because cyclodextrins have such a good regulatory profile and are so well established in how you can use them safely, industrially, in food, in medicine, we think that the pathway to turning this into an actually effective drug - that we can write a plan, and have it be realistic is good. We're talking to experts on formulation and manufacturing, and what you see on this slide are realistic timelines. We're developing some more assays that we think will be more effacious; assays that will demonstrate that we can reverse a foam cell phenotype for example, or remove 7-ketocholesterol from plaque samples that we're working on getting from human patients or cadavers. So we have a detailed month by month plan on how we think that we could get a drug to clinical trials in three years.

As Aubrey said, we're working and making great strides on turning this into a SENS Research Foundation spinout, wholly incubated and owned at the foundation. We're calling it Underdog Pharmaceuticals.

An Interview with Aubrey de Grey at Longevity.Technology

It is always pleasant to see new efforts to produce longevity-focused interest sites and publications; Longevity.Technology is a recent example, here publishing an interview with Aubrey de Grey of the SENS Research Foundation that touches on recent developments in the field of rejuvenation research. There have been many such news organization initiatives over the past ten to fifteen years, and all too few of them lasted. Hopefully that will change now that an industry of rejuvenation is forming, beginning with the development of senolytic therapies, and ever greater degrees of funding and attention are directed towards this part of the life science field. If we look at larger fields, enough of that funding and attention can spill over to support a community focused on analysis, reporting, and other such work. That should happen here as well.

We've read a lot of very compelling reasons from you as to why we as a society should care about aging, but we're very curious what made you care about it?

Nothing really made me care about it. It was always obvious to me that it was the number one most important problem in the world. It's the thing that causes by far the greatest amount of suffering and everyone gets it. The astonishing thing was that other people didn't think that way. In fact, I only discovered that others didn't in my late 20s. I had gone through my entire life presuming that it was as obvious as the colour of the sky. It wasn't something I would even have conversations about, so I'd never done the experiment to determine whether anyone else agreed. Then I met my ex-wife, who was quite a senior biologist at the time. And I began to discover that, actually, people didn't think that way, not even in biology. And hardly any work was being done to deal with this problem. So I thought "Well, that won't do."

What is the SENS platform and why did you need to create it?

SENS stands for Strategies for Engineered Negligible Senescence. It's a formal name for the way my organisation, the SENS Research Foundation, develops therapies for the diseases and disabilities of aging. I was able to see that there was indeed a very different, and entirely overlooked, approach to dealing with aging. And it was something the people who were studying it weren't doing: that we should essentially be trying to repair damage in the body. When I'm feeling frivolous, I like to compare gerontologists of that era to seismologists. What they studied was bad for you, but they had no idea whatsoever how they could actually do anything about it. I stuck to my guns, stood my ground and people have gradually caught up and understood the kinds of things I've been saying all the time. Now it's totally mainstream - orthodox - and people are reinventing the idea in slightly different language. So that's all very nice.

What undeveloped areas are you working on at the moments?

One that really is a centrepiece project in-house (and has been for quite some time) is to put back-up copies of the mitochondrial DNA in the cell nucleus. For non-biologists who are reading, mitochondria are very essential parts of each cell that perform the chemistry of breathing. They combine oxygen with nutrients in order to extract energy from those nutrients. And, unlike any other part of the cell, the mitochondria have their own DNA - separate from the DNA of the nucleus.

But the process of extracting energy from nutrients using oxygen is chemically hairy, producing a load of by-products (in particular free radicals) that can damage the mitochondrial DNA and give it a really bad day. So the idea that we've taken, that was put forward in the mid 80s, is to essentially put copies of the mitochondrial DNA inside the nucleus, modified so that it still works in there, to shield it from this damage. It's not as hard as it sounds, but it still is very hard! People gave up on it ... they thought it was too hard. I thought that they'd given up a bit too easily. And it turns out I was right - we had to work about ten years or so before we eventually got to the point of being able to publish a single paper on this. But we eventually got there a couple of years ago, and now we have a second paper in the works demonstrating that we have done most of the job.


The Longevity Associated Variant of BPIFB4

In principle, genetic variants associated with longevity should help to point out which processes are more important in the aging process, and therefore steer researchers towards more effective approaches to interventions aimed at slowing or reversing aging. In practice, however, so few longevity-associated variants have been found that little has been accomplished on this front. One of them is examined in this open access paper. The mechanism by which it contributes to longevity may be a reduction in the burden of hypertension and consequent tissue damage.

To be clear, near any study of genetics and aging turns up all sorts of variants that correlate with longevity in the study population in question, but only a handful have ever been replicated in other study populations. This tells us that the genetics of aging is a matter of hundreds or thousands of tiny, interacting contributions, highly sensitive to environmental factors. This is why I am not optimistic that genetic studies of this nature are the road to any sort of meaningful progress towards greater human longevity. Even the variant here, if it operates via a lowering of blood pressure, is a poor substitute for long-standing drugs that achieve the same result to a greater degree, and those drugs were developed without any reference to the genetic study of longevity.

Frailty reflects the individual's biological age and life expectancy better than chronological age. Studies in long-living individuals (LLIs), which, in spite of their exceptional biological age, are protected from and cope better with age-related diseases, confirm this concept. Moreover, several genetic factors that are reportedly implicated in the determination of exceptional longevity are also inversely related with frailty disabilities.

The Bactericidal/Permeability-Increasing Fold-Containing Family B member 4 (BPIFB4) gene encodes a secreted protein, initially found to be expressed in salivary glands, and more recently discovered to play important pathophysiological roles at systemic level. A genome wide association study (GWAS), performed on an Italian set of LLIs and controls and validated on two independent populations from Germany and USA, identified the BPIFB4 variants associate with lifespan.

The BPIFB4 protein is expressed in undifferentiated and highly proliferative cells and in fetal/stressed heart tissue (cardiac hypertrophy), which share a common hypoxic environment. Overexpression of BPIFB4 isoforms induced the activation of stress response-related heat-shock proteins (HSPs) and the modification of protein homeostatic processes (translation, ribosome biogenesis, spliceosome), two processes that are usually lost during aging.

Furthermore, the circulating levels of immunoreactive BPIFB4 protein are reportedly higher in healthy LLIs than in diseased LLIs or young controls. Similarly, CD34+ hematopoietic cells and mononuclear cells (MNCs) of LLIs expressed higher levels of BPIFB4 than corresponding cells of young controls. Studies in experimental models of cardiovascular disease confirmed that overexpression of the human LAV-BPIFB4 gene results in attenuation of hypertension, atherosclerosis, and ischemic disease, which are hallmarks of aging.


Embedded 3D Printing Used to Assemble Tiny Organoids into Larger Vascularized Tissue Masses

For as long as I have been watching progress in tissue engineering, the primary and most important barrier to building organs to order has been the inability to construct vascular networks. A network of capillaries must exist for blood, and thus nutrients and oxygen necessary to cell survival, to reach more than a few millimeters into a tissue. In live tissues, hundreds of minuscule capillaries pass through every square millimeter, considered in cross-section. Replicating this level of capillary density in engineered tissue has yet to be accomplished, with even the more advanced technology demonstrations falling well short of this goal.

Well funded initiatives such as the effort to produce genetically engineered pigs with organs that can be decellularized for transplantation into humans, or the application of decellularization to donor human organs, should be considered as attempts to work around the vascular challenge. That is why they exist. If a suitable vascular network cannot be produced from scratch, then the existing vascular network in an existing organ is the only viable alternative. It remains to be seen as to how long these approaches will be needed, how long it will take the research community to be able to grow larger tissues with sufficient vascular networks for practical use in medicine.

As the research community continues to wrestle with the production of vascular networks, scientists have become ever more proficient in the production of small sections of organ tissue from the starting point of a cell sample, known as organoids. Given the ability to reprogram patient cells into induced pluripotent stem cells, which can then be used to produce cells of any type, building functional organoids only requires a suitable protocol: the right signals and conditions to convince cells to form tissue as they do in the body. Discovering how to do this for the more important internal organs has proceeded apace over the past decade: livers, kidneys, lungs, the thymus, and more. As soon as a viable approach to vascularization of tissue emerges, scaled up and fully functional organs made to order will soon follow.

Sacrificial ink-writing technique allows 3D printing of large, vascularized human organ building blocks

Artificially grown human organs are seen by many as the "holy grail" for resolving the shortage of donor organs for transplant, and advances in 3D printing have led to a boom in using that technique to build living tissue constructs in the shape of human organs. However, all 3D-printed human tissues to date lack the cellular density and organ-level functions required for them to be used in organ repair and replacement. Now, a new technique called SWIFT (sacrificial writing into functional tissue) overcomes that major hurdle by 3D printing vascular channels into living matrices composed of stem-cell-derived organ building blocks (OBBs), yielding viable, organ-specific tissues with high cell density and function.

"This is an entirely new paradigm for tissue fabrication. Rather than trying to 3D-print an entire organ's worth of cells, SWIFT focuses on only printing the vessels necessary to support a living tissue construct that contains large quantities of OBBs, which may ultimately be used therapeutically to repair and replace human organs with lab-grown versions containing patients' own cells."

SWIFT involves a two-step process that begins with forming hundreds of thousands of stem-cell-derived aggregates into a dense, living matrix of OBBs that contains about 200 million cells per milliliter. Next, a vascular network through which oxygen and other nutrients can be delivered to the cells is embedded within the matrix by writing and removing a sacrificial ink. "Forming a dense matrix from these OBBs kills two birds with one stone: not only does it achieve a high cellular density akin to that of human organs, but the matrix's viscosity also enables printing of a pervasive network of perfusable channels within it to mimic the blood vessels that support human organs."

Biomanufacturing of organ-specific tissues with high cellular density and embedded vascular channels

Engineering organ-specific tissues for therapeutic applications is a grand challenge, requiring the fabrication and maintenance of densely cellular constructs. Organ building blocks (OBBs) composed of patient-specific-induced pluripotent stem cell-derived organoids offer a pathway to achieving tissues with the requisite cellular density, microarchitecture, and function. However, to date, scant attention has been devoted to their assembly into 3D tissue constructs.

Here, we report a biomanufacturing method for assembling hundreds of thousands of these OBBs into living matrices with high cellular density into which perfusable vascular channels are introduced via embedded three-dimensional bioprinting. The OBB matrices exhibit the desired self-healing, viscoplastic behavior required for sacrificial writing into functional tissue (SWIFT). As an exemplar, we created a perfusable cardiac tissue that fuses and beats synchronously over a 7-day period. Our SWIFT biomanufacturing method enables the rapid assembly of perfusable patient- and organ-specific tissues at therapeutic scales.

Evidence for an Intestinal Origin of Parkinson's Disease

As is the case for many neurodegenerative conditions, Parkinson's disease is associated with the spread of protein aggregation. Specific proteins become changed in ways that cause them to form solid deposits, surrounded by a halo of associated toxic biochemistry that harms neurons. The aggregates in Parkinson's patients are formed from α-synuclein, and here, researchers provide evidence for the origins of α-synuclein related neurological dysfunction to begin in the intestine, and only later migrate to the brain.

Parkinson's disease is characterised by a slow destruction of the brain due to the accumulation of the protein alpha-synuclein and the subsequent damage to nerve cells. The disease leads to shaking, muscle stiffness, and characteristic slow movements of sufferers. In a new research project, scientists used genetically modified laboratory rats which overexpress large amounts of the alpha-synuclein protein. These rats have an increased propensity to accumulate harmful varieties of alpha-synuclein protein and to develop symptoms similar to those seen in Parkinson's patients. The researchers initiated the disease process by injecting alpha-synuclein into the small intestines of the rats.

"After two months, we saw that the alpha-synuclein had travelled to the brain via the peripheral nerves with involvement of precisely those structures known to be affected in connection with Parkinson's disease in humans. After four months, the magnitude of the pathology was even greater. It was actually pretty striking to see how quickly it happened."

Patients with Parkinson's disease often already have significant damage to their nervous system at the time of diagnosis, but it is actually possible to detect pathological alpha-synuclein in the gut up to twenty years before diagnosis. "With this new study, we've uncovered exactly how the disease is likely to spread from the intestines of people. We probably cannot develop effective medical treatments that halt the disease without knowing where it starts and how it spreads - so this is an important step in our research. Parkinson's is a complex disease that we're still trying to understand. However, with this study and a similar study that has recently arrived at the same result using mice, the suspicion that the disease begins in the gut of some patients has gained considerable support."


Senolytic Treatment Reverses Age-Related Loss of Regenerative Capacity in the Liver

You might recall a paper published last year in which the authors reported that cellular senescence is a primary cause of declining capacity in liver regeneration with age. Here the obvious next step is taken, and a senolytic therapy is tested for its ability to restore the capacity of the aging liver to regenerate by clearing senescent cells. Improvement in all sorts of measures that normally decline with age is the expected result of senolytic treatment at this point, given the extensive evidence accumulated to date. Senescent cells are a cause of aging and age-related decline, they actively maintain a dysfunction state of metabolism via their secretions, and thus of course getting rid of them helps. Though, as noted in this paper, things are never as simple as we might hope them to be.

Many tissues, including the liver, heart and limbs possess a limited regenerative capacity in newborn or young mice, but which is lost upon maturation. As far as we are aware, misregulation of senescence has not been causally linked to such loss of regenerative capacity. Here, we first assessed the dynamic patterns of senescence markers during liver regeneration in young and adult mice. Although a transient p53-independent increase in p21 is well described following partial hepatectomy, its precise functions remain unclear, and loss of p21 does not seem to adversely impact regeneration in young animals. However, in models of advanced aging and severe liver damage, aberrantly expressed senescence markers, including p21 and p16Ink4a have been reported to impede liver regeneration. For example, in models of liver fibrosis, a robust senescence response is induced primarily in the stellate cells, which serves to limit fibrosis. Other models of severe liver damage induce a pronounced p21-expressionin hepatocytes, which results in decreased regeneration, senescence,and senescence-spreading.

We find that following partial hepatectomy, the senescence markers p21, p16Ink4a, and p19Arf become dynamically expressed at an age when regenerative capacity decreases. In addition, we demonstrate that treatment with a senescence-inhibiting drug improves regenerative capacity, through targeting of aberrant p21 expression. Surprisingly, we also find that the senescence marker p16Ink4a is expressed in a different cell-population to p21, and is unaffected by senescence targeting. This work suggests that senescence may initially develop as a heterogeneous cellular response, and that treatment with senolytic drugs may aid in promoting organ regeneration.

Senolytic treatment is increasingly shown to have beneficial effects in enhancing tissue function and alleviating disease symptoms in a variety of tissues. However, in many cases, the specific cellular targets or molecular mediators in vivo remain to be identified. Our study suggests that p21-positive cells may be a primary target. This is supported by the findings that protection from apoptosis is a main function of p21, including in senescent cells, and many senolytics, including the one used here, work by blocking anti-apoptotic pathways. In addition,as p21 functions to protect cells from damage, prolonged loss of p21 in aging mice predisposes to cancer through loss of this cytoprotective effect.

Interestingly, our study suggests that a one-time removal of p21 positive cells using a senolytic has a beneficial effect on regeneration, but probably without the long-term consequences of p21-loss. Surprisingly however, we see no effect of senolytic treatment on the increased expression of p16Ink4a that is present prior to hepatectomy, and which becomes detectable at the same stage as the decrease in regenerative capacity. Many studies show how targeting p16Ink4a expression has beneficial effects on aged and damaged tissue. However, in most cases, this also results in reduction of p21 and p19Arf, making it difficult to discern specific effects of each gene.

As p16Ink4a and p21 are expressed in different cell populations in our study, this hints that p16Ink4a, at this level of expression at least, may have beneficial effects in the liver also. However, why senolytic treatment seems to eliminate p16Ink4a positive cells in other contexts and not here remains unknown, but probably relates to the level of p16Ink4a-expression or co-expression with other senescence genes, as p16Ink4a levels become increasingly higher with age. Perhaps with advanced age or chronic damage, p21 and p16Ink4a become co-expressed, and at higher levels in the same cell types, resulting in a full-senescence response, and what we witness here is an early stage in a cumulative and progressive decline that becomes more complex over time.


Short Term versus Long Term Gains in Working Memory Following Exercise

Research has established that exercise rapidly produces an improvement in memory function, within a matter of minutes. It is also the case that regular exercise slows cognitive decline with age and taking up exercise improves cognitive function in older individuals, when considered over the long term rather than immediately following exercise. Given that only a minority of the population in wealthier parts of the world, and particularly the older segment of the population, exercise to the degree recommended to best maintain health, these findings should probably be considered more a case of people doing themselves harm than a case of there being benefits to be obtained.

Today's research materials are interesting for directly comparing the short term and long term benefits of exercise to the operation of working memory in older people. The effect size is about the same, in that the same degree of improvement is observed immediately following exercise versus after a period of regular exercise, but the former benefit is very short-lived, while the latter benefit is sustained over time. The short-term benefit is also only observed in some people, and those differences correlated with structural differences in the brain. Is this all of any practical use at the present time, beyond being yet another recommendation to undertake more exercise? Probably not, but in the long term there is no such thing as useless knowledge.

New study suggests exercise is good for the aging brain

Researchers have found that a single bout of exercise improves cognitive functions and working memory in some older people. In experiments that included physical activity, brain scans, and working memory tests, the researchers also found that participants experienced the same cognitive benefits and improved memory, for a short time, from a single exercise session as they did in a sustained fashion from longer, regular exercise.

Previous research has shown exercise can confer a mental boost. But the benefits vary: One person may improve cognitively and have improved memory, while another person may show little to no gain. Limited research has been done on how a single bout of physical activity may affect cognition and working memory specifically in older populations, despite evidence that some brain functions slip as people age. Researchers wanted to tease out how a single session of exercise may affect older individuals. The team enrolled 34 adults between 60 and 80 years of age who were healthy but not regularly active. Each participant rode a stationary bike on two separate occasions - with light and then more strenuous resistance when pedaling - for 20 minutes. Before and after each exercise session, each participant underwent a brain scan and completed a memory test.

After a single exercise session, the researchers found in some individuals increased connectivity between the medial temporal lobe (which surrounds the brain's memory center, the hippocampus) and the parietal cortex and prefrontal cortex, two regions involved in cognition and memory. Those same individuals also performed better on the memory tests. Other individuals showed little to no gain. The boost in cognition and memory from a single exercise session lasted only a short while for those who showed gains, the researchers found.

The participants also engaged in regular exercise, pedaling on a stationary bike for 50 minutes three times a week for three months. One group engaged in moderate-intensity pedaling, while another group had a mostly lighter workout in which the bike pedals moved for them. Most individuals in the moderate and lighter-intensity groups showed mental benefits, judging by the brain scans and working memory tests given at the beginning and at the end of the three-month exercise period. But the brain gains were no greater than the improvements from when they had exercised a single time.

Acute Exercise Effects Predict Training Change in Cognition and Connectivity

Previous studies report memory and functional connectivity of memory systems improve acutely after a single aerobic exercise session or with training, suggesting the acute effects of aerobic exercise may reflect initial changes that adapt over time. In this trial, for the first time, we test the proof-of-concept of whether the acute and training effects of aerobic exercise on working memory and brain network connectivity are related in the same participants. Cognitively normal older participants (N=34) were enrolled in a randomized clinical trial. Participants completed fMRI resting state and a working memory task acutely after light and moderate intensity exercise and after a 12-week aerobic training intervention.

Functional connectivity did not change more after moderate compared with light intensity training. However, both training groups showed similar changes in cardiorespiratory fitness (maximal exercise oxygen uptake, VO2peak), limiting group-level comparisons. Acute effects of moderate intensity aerobic exercise on hippocampal-cortical connections in the default network predicted training enhancements in the same connections. Working memory also improved acutely, especially following moderate intensity, and greater acute improvements predicted greater working memory improvement with training. Exercise effects on functional connectivity of right lateralized fronto-parietal connections were related to both acute and training gains in working memory.

Repair of a Damaged Cornea Using Cells Derived from Induced Pluripotent Stem Cells

Since the discovery of induced pluripotency more than a decade ago, researchers have been working towards the use of this technology to produce cells for use in tissue engineering and regenerative therapies. Induced pluripotent stem cells are functionally equivalent to embryonic stem cells; given suitable recipes and methods for the surrounding environment and signals, they can be made to generate any of the cell types in the body. The cornea of the eye is a comparatively simple starting point for tissue engineering, easier to work with in many ways, in generating tissues and in delivering cells to the patient. Here, the first repair of a human cornea is reported, using tissue structures produced from induced pluripotent stem cells.

A Japanese woman in her forties has become the first person in the world to have her cornea repaired using reprogrammed stem cells. The woman has a disease in which the stem cells that repair the cornea, a transparent layer that covers and protects the eye, are lost. The condition makes vision blurry and can lead to blindness. To treat the woman, researchers created sheets of corneal cells from induced pluripotent stem (iPS) cells. These are made by reprogramming adult skin cells from a donor into an embryonic-like state from which they can transform into other cell types, such as corneal cells.

The woman's cornea remained clear and her vision had improved since the transplant a month ago. Currently people with damaged or diseased corneas are generally treated using tissue from donors who have died, but there is a long waiting list for such tissue in Japan. Japan has been ahead of the curve in approving the clinical use of iPS cells, which were discovered by stem-cell biologist Shinya Yamanaka. Japanese physicians have also used iPS cells to treat spinal cord injury, Parkinson's disease, and another eye disease. The Japanese health ministry gave permission to try the procedure on four people. The team is planning the next operation for later this year and hope to have the procedure in the clinic in five years.


LEAF Interviews David Sinclair

David Sinclair recently published a new book to assist in publicizing his present research directions, companies, and thinking on aging, and is here interviewed by the Life Extension Advocacy Foundation (LEAF) volunteers. The work presently underway includes supplements to increase levels of NAD+ in mitochondria and, separately, partial reprogramming of cells in a living individual in order to gain some of the effects of full reprogramming, particularly restoration of mitochondrial function. Fully reprogramming cells into induced pluripotent stem cells has been shown to clear out dysfunctional mitochondria and reset epigenetic markers of age to a more youthful configuration.

It is worth noting that this strategy will not be able to fix a great many of the issues that arise in cells with age, such as the accumulation of metabolic waste that even youthful cells cannot break down effectively. If it can be used to safely restore mitochondrial function in old tissues for an extended period of time, however, then that is certainly interesting enough to chase aggressively in and of itself. Mitochondrial dysfunction is a noteworthy aspect of aging, and is involved in numerous age-related diseases.

Currently, medicine treats the symptoms, not the causes, of age-related diseases. Do you think that we might soon reach the point where therapies will be taken in a preventive manner to delay the onset of age-related diseases?

Well, there's a subset of the population, particularly in the US, but increasingly around the world, who are using the internet to educate themselves and are trying to take action before they become sick. Sometimes with medical supervision, sometimes not. It's a grassroots movement right now; for it to become mainstream, the regulations would have to change so that doctors can feel comfortable prescribing medicines to prevent diseases. But, if we don't change, then we will continue to practice whack-a-mole medicine and only treat one disease at a time after it's already developed.

You are very well known for your work with NAD+ and its precursors; we're often asked whether nicotinamide riboside or nicotinamide mononucleotide is better?

They're very similar molecules, and both have been shown to provide a variety of health benefits in mice. That doesn't mean either of them will work to slow aging in humans, and that's why placebo-controlled clinical trials are required to know if one of them, or both of them, will work in certain conditions. Those studies began over a year ago, and they are currently Phase 1 safety studies in healthy volunteers. Next year, the plan is to test the pharmaceutical product in a disease area, most likely a rare disease, but also in the elderly to see if we can recapitulate some of the results we've seen in mice, such as increased blood flow and endurance.

Another area that you are involved in is partial cellular reprogramming to reverse age-related epigenetic alterations in cells and tissues. Please tell us a little bit about this approach and the approach that you are taking and how you're progressing so far?

For 20 years, we've been working on epigenetic changes as a cause of aging, starting with work in yeast and now in mammals. We've developed viral vectors and combinations of reprogramming factors that appear to be much safer than past approaches, and we've used them to reprogram the eye to restore vision in mice with glaucoma and in very old mice. Currently, it is believed that the epigenetic clock is just an indicator of age and not part of the actual aging process, but our recent work strongly suggests that the process of reversing the clock doesn't just change the apparent age of the body, it actually reverses aging itself by restoring the function of the old cells to behave as though they're young again. Therefore, the clock may not just be telling time; it may actually be controlling time.

Could you please tell us a little bit about your book and what the readers should look forward to?

"Lifespan: Why We Age and Why We Don't Have To" takes the reader on a journey through history, looking at the endeavor of humans to try to live longer and using that historical perspective to look at today's situation and project into the future. The book also takes readers on a journey through the very cutting edge of aging research and things that the reader can do right now to take advantage of these new discoveries in their daily lives with changes in their daily activity, what they eat, when they eat, but also medicines that are currently available on the market that may extend lifespan. The last chapter is about where we are headed, what are the medicines that are in development, and then when these drugs become available, what does the world look like? Is it a better place or a worse place, and how will our lives change?


Lower LDL Cholesterol and Blood Pressure Over a Lifetime Correlate with Greatly Reduced Risk of Cardiovascular Disease

Numerous genetic variants correlate with either lower LDL cholesterol or lower blood pressure. Some of these have been shown to result in greatly reduced risk of cardiovascular disease, such as variants in APOB, DSCAML1, ANGPTL4, and ASGR1. Researchers here adopt the position that one can use data on the health of individuals with these and other variants from a large population database as a way to model the outcome should a non-variant individual diligently control LDL cholesterol and blood pressure through lifestyle choices throughout life. This is probably a fair assumption, though it is also fair to suggest that not all of the relevant mechanisms touched on by these genetic variants are fully understood.

As one might expect, based on the results from earlier studies of specific variants and risk of cardiovascular disease, the data here shows a large reduction in risk for people who have one or more of these variants. This can then be associated with the level of reduction in LDL cholesterol and blood pressure needed for a non-variant individual to achieve the same outcome. Assuming, of course, that cholesterol levels and blood pressure are the only relevant mechanisms, or at least the dominant mechanisms. They are undoubtedly influential, given that higher LDL cholesterol accelerates atherosclerosis and higher blood pressure results in all sorts of tissue damage, but they are not the only influential processes in aging.

A life of low cholesterol and BP slashes heart and circulatory disease risk

In this study, researchers studied 438,952 participants in the UK Biobank, who had a total of 24,980 major coronary events - defined as the first occurrence of non-fatal heart attack, ischaemic stroke, or death due to coronary heart disease. They used an approach called Mendelian randomisation, which uses naturally occurring genetic differences to randomly divide the participants into groups, mimicking the effects of running a clinical trial.

People with genes associated with lower blood pressure, lower LDL cholesterol, and a combination of both were put into different groups, and compared against those without these genetic associations. Differences in blood LDL cholesterol and systolic blood pressure (the highest level that blood pressure reaches when the heart contracts), along with the number of cardiovascular events was compared between groups.

A long-term reduction of 1 mmol/L low-density lipoprotein (LDL), or 'bad' cholesterol, in the blood with a 10 mmHg reduction in blood pressure led to an 80 percent lower lifetime risk of developing heart and circulatory disease. This combination also reduced the risk of death from these conditions by 67 percent. The team found that even small reductions can provide health benefits. A decrease of 0.3 mmol/L LDL cholesterol in the blood and 3 mmHg lower blood pressure was associated with a 50 percent lower lifetime risk of heart and circulatory disease.

Association of Genetic Variants Related to Combined Exposure to Lower Low-Density Lipoproteins and Lower Systolic Blood Pressure With Lifetime Risk of Cardiovascular Disease

Numerous randomized trials have demonstrated that treatment for up to 5 years with therapies that reduce low-density lipoprotein cholesterol (LDL-C) and systolic blood pressure (SBP) reduce the risk of cardiovascular events. In addition, mendelian randomization studies suggest that the benefit of exposure to lower LDL-C levels and lower SBP may accumulate over time. Because the biological effects of LDL-C and SBP may be cumulative, long-term exposure to the combination of both could potentially substantially reduce the lifetime risk of cardiovascular disease. However, the association of combined lifetime exposure to both lower LDL-C and lower SBP with the risk of cardiovascular disease has not been reliably quantified.

Ideally, this question would be addressed by conducting a randomized trial to minimize the effect of confounding that can occur in observational studies. However, a randomized trial evaluating the association between maintaining prolonged exposure to both lower LDL-C levels and lower SBP with the risk of cardiovascular disease would take several decades to complete, and therefore is unlikely to ever be conducted.

In an attempt to fill this evidence gap, this study used genetic variants associated with lower LDL-C levels and SBP as instruments of randomization to divide participants into groups with lifelong exposure to lower LDL-C levels, lower SBP, or both; and then compared the differences in plasma LDL-C, SBP, and cardiovascular event rates in each group to estimate the association of combined lifetime exposure with the lifetime risk of cardiovascular disease in a manner analogous to a long-term randomized clinical trial. The primary objective of this study was to assess and quantify the association of prolonged exposure to the combination of both lower LDL-C and lower SBP with the lifetime risk of cardiovascular disease.

Upregulation of Autophagy Reverses Age-Related Decline of Memory B Cell Function

Memory B cells undertake some of the more important tasks in coordination of an effective immune response, circulating in the body to accelerate the deployment of other resources in the immune system to tackle a specific threat. Dysfunction in B cells is a significant component of the onset of age-related immunosenescence, the progressively greater incapacity of the immune system. Selectively removing and replacing B cells has been shown to improve matters, but here researchers identify failing autophagy as an important factor. B cells are long-lived, and long-lived cells tend to build up metabolic waste that is resilient to the enzymes available to break it down. This gums up the structures and systems used in autophagy, causing it to fail, and the cells to thus become ever more cluttered with damaged protein machinery and other harmful waste. This in turn degrades function.

During a regular influenza season, about 90% of the deaths occur in people older than 65 years. Immune responses to vaccines are known to be particularly ineffective in the elderly population. A major correlate of protection for vaccinations is the specific antibody titer generated by long-lived plasma B cells. With a lifespan of several decades, long-lived lymphocytes are particularly prone to accumulation of intracellular waste. Autophagy recycles unwanted cytoplasmic material. Autophagy-deficient lymphocytes are unable to generate adequate responses, in particular long-lived lymphocytes, memory T cells, memory B cells, and plasma B cells.

Here we show that reduced autophagy is a central molecular mechanism underlying immune senescence. Autophagy levels are specifically reduced in mature lymphocytes, leading to compromised memory B cell responses in old individuals. Spermidine, an endogenous polyamine metabolite, induces autophagy in vivo and rejuvenates memory B cell responses. Mechanistically, spermidine post-translationally modifies the translation factor eIF5A, which is essential for the synthesis of the autophagy transcription factor TFEB. Spermidine is depleted in the elderly, leading to reduced TFEB expression and autophagy. Spermidine supplementation restored this pathway and improved the responses of old human B cells. Taken together, our results reveal an unexpected autophagy regulatory mechanism mediated by eIF5A at the translational level, which can be harnessed to reverse immune senescence in humans.


Dsyfunctional Autophagy Promotes Cellular Senescence in Long-Lived Neurons

Senescent cells cause harm to surrounding tissue when they linger over time, evading the usual fate of self-destruction or destruction by the immune system. They secrete inflammatory and other signals that rouse the immune system into a state of chronic inflammation, destructively remodel nearby tissue, and encourage other cells to become senescent. The presence of senescent cells is a significant cause of aging and age-related disease, as demonstrated by studies in which senolytic therapies are used to selectively remove some portion of the burden of senescent cell in old tissues.

Researchers here show that long-lived non-dividing cells in the brain also become senescent, and that a faltering of the cell maintenance processes of autophagy is important in this process. One of the reasons why autophagy declines with age, particularly in long-lived cells, is the build up of hardy metabolic waste products that clutter the recycling structures called lysosomes, making them inefficient and bloated. More effort should be devoted towards building therapies capable of breaking down the waste products that our biochemistry struggles with.

Senescent cells accumulate in various tissues and organs with aging altering surrounding tissue due to an active secretome, and at least in mice their elimination extends healthy lifespan and ameliorates several chronic diseases. Whether all cell types senesce, including post-mitotic cells, has been poorly described mainly because cellular senescence was defined as a permanent cell cycle arrest. Nevertheless, neurons with features of senescence have been described in old rodent and human brains.

In this study we characterized an in vitro model useful to study the molecular basis of senescence of primary rat cortical cells that recapitulates senescent features described in brain aging. We found that in long-term cultures, rat primary cortical neurons displayed features of cellular senescence before glial cells did, and developed a functional senescence-associated secretory phenotype able to induce paracrine premature senescence of mouse embryonic fibroblasts but proliferation of rat glial cells.

Functional autophagy seems to prevent neuronal senescence, as we observed an autophagic flux reduction in senescent neurons both in vitro and in vivo, and autophagy impairment induced cortical cell senescence while autophagy stimulation inhibited it. Our findings suggest that aging-associated dysfunctional autophagy contributes to senescence transition also in neuronal cells.


Clonal Mutation in Immune Cells Correlates with Epigenetic Age Acceleration

The nuclear DNA encoding near all of the protein machinery necessary to cell function is constantly damaged and constantly repaired. The repair mechanisms are highly efficient, and are backed up by numerous other systems intended to destroy cells that suffer particularly critical DNA damage, mutations that can lead to cancer or severe dysfunction. Nonetheless, damage accumulates. Near all of this damage is irrelevant, as it occurs randomly in single somatic cells with a limited life span, in genes that the cell isn't using. Unfortunately, there are ways for DNA damage to become significant.

The first is obviously cancer, a condition arising from particular combinations of mutational damage that allow a cell to replicate aggressively without limit. The second is when damage occurs in a stem cell or progenitor cell that will create large numbers of descendant somatic cells. A mutation can be spread widely throughout a tissue, and the resulting patchwork of mutations is known as somatic mosaicism. It is thought that somatic mosaicism contributes to the general level of dysfunction in aging tissue, but this is hard to prove at the present time: the compelling experiment that isolates only this class of nuclear DNA damage as a factor and links it to specific aspects of aging has yet to be designed and carried out. It is easy to generate nuclear DNA damage in animal models, via radiation or genetic engineering to disable repair mechanisms, and indeed this causes harm, but it is not the same thing at all.

Today's research is focused on a form of somatic mosaicism in the immune system, known as age-related clonal haemopoiesis (ARCH), this designation limited to mutations in a small range of genes associated with cancer risk. Mutations arise in hematopoietic stem cells or progenitor cells, just as elsewhere, and as a consequence large numbers of immune cells bear those mutations. When this occurs in the ARCH genes related to cancers of the immune system, such as leukemia, it raises the risk of cancer and earlier mortality, the latter possibly due to increased risk of cardiovascular disease. One can speculate on why the increased risk of cardiovascular disease occurs, such as the importance of macrophages to the development of atherosclerosis, but a solid understanding is lacking.

In the same vein, researchers here show that age-related clonal haemopoiesis is correlated with an increased epigenetic age. At this point an acceleration of epigenetic age, to have a higher epigenetic age than chronological age, should probably be expected for any underlying state that raises all cause mortality, given the large amount of evidence for patients with specific age-related diseases to have higher epigenetic age measures. Unfortunately we don't yet have a reliable technology that allows low-risk replacement of hematopoietic stem cell populations: it is possible via hematopoietic stem cell transplantation, but this is a traumatic procedure involving chemotherapy and significant side-effects. But given a way to safely destroy existing hematopoietic cell populations and introduce new undamaged populations, a great many issues in aging might be addressed meaningfully. It is a goal to work towards.

DNA changes accelerate body's ageing

DNA changes throughout a person's life can significantly increase their susceptibility to heart conditions and other age-related diseases, research suggests. Such alterations - known as somatic mutations - can impact the way blood stem cells work and are associated with blood cancers and other conditions. A study says that these somatic mutations and the associated diseases they cause may accelerate a person's biological age - how old their body appears - faster than their chronological age - the number of years they have been alive.

A study examined these changes and their potential effects in more than 1000 older people from the Lothian Birth Cohorts (LBCs), born in 1921 and 1936. The LBCs are a group of people - now in their 80s and 90s - who sat intelligence tests as 11-year olds. They are some of the most-intensively studied research participants in the world. Scientists studied people where the biological and chronological age was separated by a large gap. They found the participants with somatic mutations - around six per cent - had a biological age almost four years older than those with no alterations. Experts say they will now explore the link between these DNA changes and biological ageing acceleration.

Age-related clonal haemopoiesis is associated with increased epigenetic age

Age-related clonal haemopoiesis (ARCH) in healthy individuals was initially observed through an increased skewing in X-chromosome inactivation. More recently, several groups reported that ARCH is driven by somatic mutations, with the most prevalent ARCH mutations being in the DNMT3A and TET2 genes, previously described as drivers of myeloid malignancies. ARCH is associated with an increased risk for haematological cancers. ARCH also confers an increased risk for non-haematological diseases, such as cardiovascular disease, atherosclerosis, and chronic ischemic heart failure, for which age is a main risk factor.

Whether ARCH is linked to accelerated ageing has remained unexplored. The most accurate and commonly used tools to measure age acceleration are epigenetic clocks: they are based on age-related methylation differences at specific CpG sites. Deviations from chronological age towards an increased epigenetic age have been associated with increased risk of earlier mortality and age-related morbidities. Here we present evidence of accelerated epigenetic age in individuals with ARCH.

Oral Bacteria Mediate Short Term Lowering of Blood Pressure Following Exercise

One of the benefits of exercise is improved cardiovascular function, and one of the ways in which this manifests is a reduced blood pressure. Maintaining a lower blood pressure is very influential over the course of aging; age-related hypertension is very damaging. Exercise tends to exhibit short term benefits immediately following a session, and then similar long term benefits when exercise is regular. Here, researchers show that the short term reduction in blood pressure following exercise is mediated in large part by oral bacteria, a most interesting finding. Whether this holds up over the long term and regular use of antibacterial mouthwash at times unrelated to exercise is another question entirely, of course. If anything, modern dentistry is the story of a futile struggle to keep any sort of oral bacteria population suppressed for any length of time.

Scientists know that blood vessels open up during exercise, as the production of nitric oxide increases the diameter of the blood vessels (known as vasodilation), increasing blood flow circulation to active muscles. What has remained a mystery is how blood circulation remains higher after exercise, in turn triggering a blood-pressure lowering response known as post-exercise hypotension. Previous research has suggested that nitric oxide was not involved in this post-exercise response - and only involved during exercise - but the new study challenges these views.

"It's all to do with nitric oxide degrading into a compound called nitrate, which for years was thought to have no function in the body. But research over the last decade has shown that nitrate can be absorbed in the salivary glands and excreted with saliva in the mouth. Some species of bacteria in the mouth can use nitrate and convert into nitrite - a very important molecule that can enhance the production of nitric oxide in the body. And when nitrite in saliva is swallowed, part of this molecule is rapidly absorbed into the circulation and reduced back to nitric oxide. This helps to maintain a widening of blood vessels which leads to a sustained lowering of blood pressure after exercise."

Twenty-three healthy adults were asked to run on a treadmill for a total of 30 minutes on two separate occasions, after which they were monitored for two hours. On each occasion at one, 30, 60 and 90 minutes after exercise they were asked to rinse their mouths with a liquid - either antibacterial mouthwash (0.2 per cent chlorhexidine) or a placebo of mint-flavoured water. Their blood pressure was measured and saliva and blood samples were taken before exercise and at 120 minutes after exercise. No food or drink except water was allowed during exercise and the recovery period, and none of the study participants had any oral health conditions.

The study found that when participants rinsed with the placebo, the average reduction in systolic blood pressure was -5.2 mmHg at one hour after exercise. However when participants rinsed with the antibacterial mouthwash, the average systolic blood pressure was -2.0 mmHg at the same time point. These results show that the blood pressure-lowering effect of exercise was diminished by more than 60 per cent over the first hour of recovery, and totally abolished two hours after exercise when participants were given the antibacterial mouthwash. Previous views also suggested that the main source of nitrite in the circulation after exercise was nitric oxide formed during exercise in the endothelial cells (cells that line the blood vessels). However, the new study challenges this. When antibacterial mouthwash was given to the participants, their blood nitrite levels did not increase after exercise.


Long-Lived Dwarf Mice Exhibit an Improved Mitochondrial Stress Response

Snell dwarf mice in which growth hormone has been disabled live significantly longer than their peers. Suppression of growth hormone activity is one of the better studied interventions known to slow aging in mice, and, like calorie restriction, has led to a strong focus on stress response mechanisms in the aging research community. A majority of the means of slowing aging in short-lived laboratory species are characterized by increased cellular maintenance activities that are triggered into greater efforts by cellular stresses: heat, cold, lack of nutrients, an excess of toxic or reactive molecules, and so forth.

Declining mitochondrial function is a characteristic of aging, as quality control mechanisms falter in their operation with advancing age. Researchers here show that one of the mechanisms associated with maintaining correct mitochondrial function, the unfolded protein response, is more active in Snell dwarf mice. This is consistent with what is already known of the slowed aging in this and similar lineages, and of the importance of cellular maintenance and mitochondria in aging.

Prolonged lifespan and improved health in late adulthood can be achieved by partial inhibition of mitochondrial proteins in yeast, worms, fruit flies, and mice. Upregulation of the mitochondrial unfolded protein response (mtUPR) has been proposed as a common pathway in lifespan extension induced by mitochondrial defects. However, it is not known whether mtUPR is elevated in long-lived mouse models.

Here, we report that Snell dwarf mice, which show 30%-40% lifespan extension and prolonged healthspan, exhibit augmented mitochondrial stress responses. Cultured cells from Snell mice show elevated levels of the mitochondrial chaperone HSP60 and mitochondrial protease LONP1, two components of the mtUPR. In response to mitochondrial stress, the increase in Tfam (mitochondrial transcription factor A), a regulator of mitochondrial transcription, is higher in Snell cells, while Pgc-1α, the main regulator of mitochondrial biogenesis, is upregulated only in Snell cells. Consistent with these differences, Snell cells maintain oxidative respiration rate, ATP content, and expression of mitochondrial-DNA-encoded genes after exposure to doxycycline stress.

In vivo, compared to normal mice, Snell mice show stronger hepatic mtUPR induction and maintain mitochondrial protein stoichiometry after mitochondrial stress exposure. Overall, our work demonstrates that a long-lived mouse model exhibits improved mitochondrial stress response, and provides a rationale for future mouse lifespan studies involving compounds that induce mtUPR. Further research on mitochondrial homeostasis in long-lived mice may facilitate development of interventions that blunt mitochondrial deterioration in neurodegenerative diseases such as Alzheimer's and Parkinson's and postpone diseases of aging in humans.


Intervene Immune Publishes Thymus Regrowth Trial Results

Intervene Immune is the company formed to commercialize the methology for regrowth of thymic tissue used in the small TRIIM (Thymus Regeneration, Immunorestoration, and Insulin Mitigation) trial, a combination of growth hormone, DHEA, and metformin. As I've noted in the past, that the approach involves the use of human growth hormone over an extended period of time makes it less desirable as an intervention, but if one can gain an expectation of some thymic regeneration, leading to an extended improvement in immune function that lasts for years beyond the treatment period, then it might be worth the trade-off. In general, higher growth hormone levels are associated with a worse outcome in the study of aging, while lower levels are associated with a slowing of aging. Using growth hormone for anything other than treating rare clinical conditions of deficiency is something like burning the candle at both ends.

The thymus is an inaccessible organ in the chest responsible for transforming thymocytes created in the bone marrow into T cells of the adaptive immune system. This complicated process takes place in thymic tissue that, unfortunately, atrophies with age, becoming replaced with fat. The less tissue, the fewer T cells are generated, and the worse the function of the immune system over time. The thymus loses much of its mass quite early in life, following childhood, but the later, slower decline over the course of adult life is a different process mediated by chronic inflammation and other factors that arise with old age. The adaptive immune system is vital to health, and thus a great deal of research has taken place over the past few decades into means of thymic regeneration: upregulation of FOXN1 or related genes such as BMP4; engineering of new thymic tissue; delivery of recombinant KGF, delivery of growth hormone; sex steroid ablation; and so forth. Some are more reliable than others, and some, such as KGF, have succeeded in mice and failed in human trials.

The Intervene Immune team has presented a fair amount of data on the results from their trial at recent conferences, including epigenetic age changes, and you'll find it all in the open access paper noted here. The results unfortunately don't include all of the assays of immune cell characteristics one might want in order to be able to compare directly with the effects of sex steroid ablation in human patients, but are intriguing. (In turn the sex steroid ablation trials didn't look at thymic mass in CT scans, an unfortunate omission). Further, it isn't possible to clearly associate all of the outcomes with regrowth of thymic tissue, particularly the epigenetic age effects, given everything else the treatment might be doing. Nonetheless, taken as a whole this is good supporting evidence for those groups working on more direct approaches to the problem of the atrophied thymus, such as Lygenesis and the company Bill Cherman and I founded last year, Repair Biotechnologies.

First hint that body's 'biological age' can be reversed

A small clinical study has suggested for the first time that it might be possible to reverse the body's epigenetic clock, which measures a person's biological age. For one year, nine healthy volunteers took a cocktail of three common drugs - growth hormone and two diabetes medications - and on average shed 2.5 years of their biological ages, measured by analysing marks on a person's genomes. The participants' immune systems also showed signs of rejuvenation.

The latest trial was designed mainly to test whether growth hormone could be used safely in humans to restore tissue in the thymus gland. The gland, which is in the chest between the lungs and the breastbone, is crucial for efficient immune function. White blood cells are produced in bone marrow and then mature inside the thymus, where they become specialized T cells that help the body to fight infections and cancers. But the gland starts to shrink after puberty and increasingly becomes clogged with fat. Evidence from animal and some human studies shows that growth hormone stimulates regeneration of the thymus. But this hormone can also promote diabetes, so the trial included two widely used anti-diabetic drugs, dehydroepiandrosterone (DHEA) and metformin, in the treatment cocktail.

Checking the effect of the drugs on the participants' epigenetic clocks was an afterthought. The clinical study had finished when researchers conducted an analysis. Four different epigenetic clocks were used to assess each patient's biological age, and he found significant reversal for each trial participant in all of the tests. "This told me that the biological effect of the treatment was robust. The effect persisted in the six participants who provided a final blood sample six months after stopping the trial. Because we could follow the changes within each individual, and because the effect was so very strong in each of them, I am optimistic,"

Reversal of epigenetic aging and immunosenescent trends in humans

Thymus regeneration and reactivation by growth hormone administration have been established in aging rats and dogs by restoration of youthful thymic histology and by reversal of age-related immune deficits. The present study now establishes highly significant evidence of thymic regeneration in normal aging men accompanied by improvements in a variety of disease risk factors and age-related immunological parameters as well as significant correlations between thymic fat-free fraction (TFFF) and favorable changes in monocyte percentages and the lymphocyte-to-monocyte ratio (LMR), independent of age up to the age of 65 at the onset of treatment. These observations are consistent with the known ability of growth hormone to stimulate hematopoiesis and thymic epithelial cell proliferation. Our finding of an increase in FGF-21 levels after 12 months of treatment suggests that thymic regeneration by the present treatment may be mediated in part by this cytokine, which we believe is a novel finding.

Treatment-induced increases in naïve CD4 and naïve CD8 T cells were relatively small compared to changes reported in recombinant growth hormone treated HIV patients, but our volunteer population was pre-immunosenescent and not depleted of naïve CD4 and naïve CD8 T cells at baseline. Positive responses also occurred despite potential complications caused by lymph node aging. Therefore, the small increases observed in these cells and in CD4 T-cell recent thymic emigrants are consistent with the ultimate goal of preventing or reversing the normal age-related collapse of the TCR repertoire at ages just above those of our study population.

There may be both immunological and non-immunological mechanisms of epigenetic aging reversal. Growth hormone, DHEA, and metformin have unique effects that are in opposition to aging, and it is possible that the specific combination of these agents activates a broad enough range of therapeutic pathways to account for the previously unpredictable reversal of epigenetic aging, even independently of the immunological markers we have measured.

Inhibition of mTORC1 as a Treatment to Slow the Consequences of Muscle Aging

Inhibition of mTOR, and more specifically only its activities as a part of the mTORC1 protein complex, has been shown to slow aging in mice. This is a class of calorie restriction mimetic treatment, in that it works through many of the same beneficial stress response mechanisms as does a restricted nutrient intake. Many of the specific effects of mTORC1 inhibition in various different tissues in the body are still incompletely investigated, however. Researchers here discuss the effects of mTORC1 inhibition on the aging of muscle tissue. With age, muscle mass and strength are lost, leading to the onset of sarcopenia and contributing greatly to the condition of age-related frailty. Means to prevent this deterioration of muscle would provide a great benefit to the older population, but mTORC1 inhibition is unfortunately only a small step towards that goal.

A decade ago, rapamycin, an mTORC1 inhibitor, was reported to extend the lifespan of mice. Consistent with this, rapamycin and other mTORC1 inhibitors also protect several organs and tissues against age-related functional decline. Rapamycin's effect on aging skeletal muscle, however, was not explored until recently. It has long been known that mTORC1 activity is induced in aging muscle. Two recent reports with genetic and pharmacological evidence reveal important findings: 1) Chronic activation of mTORC1 stimulates progressive muscle damage and loss, and 2) Inhibition of mTORC1 with rapamycin prevents age-related muscle loss.

Consistent with the observation that the hyperactive mTORC1 induces muscle damage and loss, inhibition of mTORC1 activity with rapamycin or rapalogs protects aging muscle from atrophy in mice and rats. For example, treatment with rapamycin from 9 months to 30 months of age reduced apoptosis and promoted retention of peripherally located nuclei, and this was associated with reduced fiber loss in aging skeletal muscle. In a separate study, a shorter duration of rapalog treatment for 6-weeks, starting from 22 month of age, preserved both fiber size and muscle weight. These data suggest that mTORC1 is necessary and sufficient to drive skeletal muscle aging.

Do these findings conflict with the current understanding of the anabolic function of mTORC1? We do not think so. We believe the ultimate effect of mTORC1 depends upon: 1) how mTORC1 is activated, and 2) for how long mTORC1 remains activated. Akt-dependent, short-term activation of mTORC1 appears usually to be beneficial to cells, whereas Akt-independent, chronic activation of mTORC1 appears to be detrimental to cells. Akt-independent activation of mTORC1 induces catabolism in addition to its conventional anabolic activity. The progressive myopathy seen in the mTORC1-hyperactive muscle is the net outcome of a complex process that perturbs the balance between anabolism and catabolism, with catabolism winning out and leading to muscle fiber damage and loss.


Aspirin Use Fails to Postpone Disability and Improve Survival in Older Individuals

Aspirin is arguably a calorie restriction mimetic, in that it boosts the operation of the cellular maintenance processes of autophagy to some degree. Increased autophagy is a feature of many of the interventions, such as calorie restriction, that slow aging in various animal models. Aspirin can extend life in short-lived species. The fact that an ongoing trial shows it to do no such thing in humans is just one more of the many pieces of evidence to demonstrate that short-lived and long-lived species have a very different plasticity of longevity in response to upregulation of stress response systems such as autophagy. The effect size of benefits resulting from aspirin in old humans is small enough to be overwhelmed by harmful side-effects in a sizable fraction of the population - this is exactly the sort of marginal medical technology that should be sidelined in favor of better approaches to the treatment of aging.

European guidelines on the prevention of cardiovascular disease (CVD) do not recommend aspirin for individuals free from CVD due to the increased risk of major bleeding. This advice was subsequently supported by results in moderate risk patients (ARRIVE trial), diabetic patients (ASCEND trial), and in people over 70 (ASPREE trial), which demonstrated that modest reductions in CVD risk were outweighed by the increased bleeding hazard.

The primary finding from the ASPREE randomised trial was that in people aged 70 years or over with no known CVD, there was no effect of 100 mg of daily aspirin on the composite primary endpoint of disability-free survival (defined as those not reaching a primary endpoint of dementia or persistent physical disability or death). The primary endpoint was chosen to reflect the reasons for prescribing a preventive drug in an otherwise healthy elderly population.

The investigators calculated ten-year CVD risk probabilities at baseline for the 19,114 ASPREE participants using the Framingham score (up to 75 years) and the Hazard ratios for CVD reduction with aspirin version placebo were 0.72 for the group classified as high risk by the Framingham score and 0.75 for those defined as high risk by the ASCVD equations. However, this reduction in CVD did not translate to a significantly improved disability-free survival.

"The findings emphasise that the risk-benefit trade-off for aspirin use in healthy older men and women varies across levels of cardiovascular risk. It also indicates that the reduction in CVD events in the highest risk groups using current stratification methods does not identify individuals in whom this advantage translates into longer disability-free survival. Based on the results of the main ASPREE trial, daily low-dose aspirin cannot be recommended in healthy people over 70 - even in those at the greatest CVD risk. Today's analysis indicates that more refined methods are needed to pinpoint a subgroup who might gain from preventive therapy."


Exploiting Senescence Associated β-Galactosidase to Selectively Destroy Senescent Cells

The accumulation of senescent cells with age is an important contributing cause of aging. Senescent cells are created constantly in the body, as somatic cells reach the Hayflick limit, or as a result of injury or toxins or potentially cancerous molecular damage. Near all either quickly self-destruct or are destroyed by the immune system, but a small fraction linger to cause harm over the long term. Senescent cells secrete a potent inflammatory mix of molecules that rouses the immune system to chronic inflammation, degrades nearby tissue structure, and changes the behavior of normal cells for the worse. The more senescent cells present in tissue, the worse the outcome.

Means to selectively remove 25% to 50% of senescent cells, and in only some tissues, reliably reverse aspects of aging and age-related disease in mice. Since the first compelling demonstration in 2011, many studies have been carried out using what have come to be called senolytic drugs. Researchers have demonstrated the ability to turn back Alzheimer's pathology, inflammatory conditions, fibrosis in hearts, lungs, and kidneys, the aging of skin, and many more pathologies characteristic of old age. A great deal of effort is now devoted towards finding new and better approaches to targeting senescent cells for destruction, to build upon the initial therapies.

The work here is an interesting example of the type. As the paper notes, to target senescent cells, one must find a way to interact with one or more mechanisms that are unique to senescent cells. The researchers choose the presence of senescence-associated β-galactosidase, which is still one of the most widely used markers of the senescent state. β-galactosidase is a part of the collection of enzymes that cells use when stressed in order to break down unwanted molecular waste, and senescent cells produce a lot of it. Thus giving cells carefully designed molecules that will be transformed into toxic compounds via the action of β-galactosidase is a potential approach to produce quite general senolytics, capable of destroying all varieties of senescent cells in all tissues.

Galactose-modified duocarmycin prodrugs as senolytics

Recent evidence drawn from genetic models has shown that eliminating senescent cells increases lifespan, improves healthspan, and benefits the outcomes of a wide range of diseases. These studies have led to a collective effort to identify 'senolytics', drugs that selectively kill senescent cells. Several senolytics have been identified including dasatinib and quercetin, piperlongumine, FOXO4 interfering peptides, HSP90 inhibitors, or the Bcl2 family inhibitors ABT-263 (navitoclax) and ABT-737. Currently, Bcl2 family inhibitors have become the gold-standard on senolysis. Bcl2 family inhibitors eliminate a range of senescent cells in vivo and reproduce the effects observed in transgenic mice modelling senescence ablation. However, ABT-263, causes severe thrombocytopenia and neutropenia, what might complicate its use on the clinic. Moreover, it is becoming evident than different senolytics might be necessary to eliminate different types of senescent cells. Therefore, there is a need to identify additional drugs with senolytic properties.

An alternative strategy for targeting senescence, is to exploit properties that differentiate senescent from normal cells. In this regard, the senescence-associated β-galactosidase activity (SA-β-gal) is one of the more conserved and defining characteristics of senescent cells. Senescent cells present an increased lysosomal mass. As a result, senescent cells display elevated levels of lysosomal enzymes such as β-galactosidase or α-fucosidases. Indeed, it has been shown that galacto-oligosacharide encapsulated nanoparticles (GalNP) preferentially release their content on senescent cells. Consequently, this GalNP can be used in combination with different cargos to either image or kill senescent cells.

Galactose-modification has been frequently used to improve the pharmacokinetic properties or the delivery of existing drugs. In addition, galactose modification can be used to generate prodrugs that rely on β-galactosidase for controlled activation. When combined with antibody-linked β-galactosidase, this approach is known as antibody-directed enzyme prodrug therapy (ADEPT). In ADEPT, a conjugate of a tumour-specific antibody and an enzyme, such as β-galactosidase, is combined with the application of a hardly cytotoxic prodrug. By means of the enzyme in the conjugate, the prodrug is selectively cleaved in cancer cells leading to the formation of a highly cytotoxic compound. Several of these galactose-modified cytotoxic prodrugs have been described. A class of such prodrugs are galactose-modified duocarmycin (GMD) derivatives.

Here, we investigated whether galactose-modified prodrugs can preferentially kill senescent cells. We have assessed the senolytic potential of several GMD derivatives and confirmed their senolytic potential in cell culture, ex vivo and in vivo. Given the increasing list of senescence-associated diseases and the positive effects associated with senolytic treatment, we propose GMD derivatives and more generally galactose-modified prodrugs are a new class of senolytic compounds with wide therapeutic promise.

Resistance Exercise Builds Muscle Equally for Both Sedentary and Athletic Older People

Older people should undertake resistance exercise, as it has been shown to reduce risk of mortality and age-related disease. Most older people do not do this, and are therefore living with unnecessarily poor health and prospects. In this context, it is interesting to see the data presented here, in which researchers show that overall level of fitness and training in older people has no effect on the ability of resistance training to produce added muscle in a previously untrained part of the body. Yes, there are all sorts of declines relating to muscle tissue function that take place during aging, but a sedentary individual is no worse off than a fit individual in this particular aspect of muscle physiology. Thus it is is never too late to start a program of resistance exercise in order to obtain benefits to health, even if one has been sedentary throughout life.

Skeletal muscle is vital for the maintenance of physical function, nutrient deposition, and basal metabolism. Aging leads to a progressive loss of skeletal muscle, termed sarcopenia, which progresses at a rate of 0.5-1% per annum from the 5th decade, alongside 3-5-fold greater reductions in strength. Accordingly, sarcopenia may drive the development, and progression, of many adverse age-related health events and force a dependence on external healthcare services. Sarcopenia progression is thought to be underpinned by inherent aging factors (i.e., hormonal changes) and aggravated by environmental and lifestyle factors (i.e., poor nutrition, obesity, and reduced activity), that blunt the muscle protein synthesis (MPS) response to normally robust anabolic stimuli, such as hyperaminoacidemia and resistance exercise.

This age-related muscle "anabolic resistance" may be underpinned by impairments in translational efficiency in the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. Whilst resistance exercise (RE) is effective at enhancing muscle anabolic sensitivity and augmenting muscle mass and strength in older individuals, myofibrillar adaptive remodeling responses are attenuated compared with younger individuals. However, chronic structured exercise training is known to alter acute muscle protein turnover rates in young and older individuals. Therefore, commencing exercise training in early adulthood, and continuing this practice through middle-to-older age, may offset or delay the onset of muscle anabolic resistance, with implications for age-related muscle loss.

Highly active older individuals who have maintained structured exercise training habits, Master Athletes (MA), display superior indices of physiological function (VO2max and strength), muscle morphology and, typically, a more favorable body composition than their untrained age-matched counterparts (OC). The only study to date to investigate MPS in MA, reported that highly trained master triathletes (older than 50 years) displayed lower MPS rates following a bout of downhill running than younger triathletes. However, rested-state MPS was not measured, preventing firm conclusions regarding the net MPS response to the exercise stimulus. The aim of the present study was to compare 48 hour rested-state and RE-induced integrated myofibrillar protein synthesis (iMyoPS) rates between MA and age-matched untrained individuals and to establish the acute intramuscular signaling response to an acute bout of RE contraction.

Our findings demonstrate no discernible difference in rested-state or exercise-induced iMyoPS rates between MA and OC. Furthermore, we observed no clear difference in the mTORC1-mediated signaling response to exercise between MA and OC. Taken together, these data suggest that despite divergent long-term exercise habits in MA, OC possess a similar capacity to upregulate intramuscular signaling and iMyoPS in response to unaccustomed exercise contraction.


TAME Trial for the Effects of Metformin in Humans to Proceed this Year

Researchers and advocates have been trying for some years to launch the TAME trial to assess the effects of metformin on aging in humans. This is not with the hope of producing meaningful effects on the progression of aging. Metformin has a small effect size, being one of the less effective interventions that upregulates cellular stress responses, a strategy that in and of itself is weak in long-lived species such as our own. The goal is to push the FDA into accepting clinical trials that target mechanisms of aging rather than a specific named age-related condition. Metformin was chosen because its safety profile, widespread use, and length of time as an approved drug make it hard for the FDA to object on technical grounds.

I view this whole exercise as an example of the harmful distorting effect of regulation on progress in medicine: years of effort and tens of millions of dollars will be wasted on an exercise that everyone involved knows will produce only tiny gains in health and longevity at the end of the day. In a sane world, those resources could have gone towards far more effective projects, those with a much greater expectation of extending healthy human life span and producing rejuvenation in the old.

After closing the final $40m of its required $75m budget with a donation from a private source, the first drug trial directly targeting aging is set to begin at the end of this year, lead researcher Dr Nir Barzilai has revealed. Back in 2015, when his revolutionary anti-aging trial TAME finally received FDA approval, it would have been forgivable to think that Dr Barzilai had, at last, got past the hard part. But TAME went into financial limbo, with many wondering if it would ever be able to escape. His trial TAME (Targeting Aging with Metformin) had been stalled for four years while he and his colleagues engaged in funding negotiations with the US NIH (National Institute of Health). "It was down to their conservative approach over there. They really didn't understand what we were trying to achieve."

For those accustomed to judging the success of a drug trial's funding acquisition by the safety and efficacy record of its drug, TAME's funding difficulties could look confusing. Safely used and widely prescribed, the trial's antidiabetic drug, metformin, has been US FDA approved since 1994. Its use in medical practice extends back into the Middle Ages, where it was extracted from the French lilac and later in France from the 1950s onwards, when the isolated compound was first successfully administered to diabetic patients.

But it is much more the trial structure, rather than the drug itself, that is on trial. Instead of following a traditional structure given to FDA approved trials (that look for a single disease endpoint) TAME has a composite primary endpoint - of stroke, heart failure, dementia, myocardial infarction, cancer, and death. Rather than attempting to cure one endpoint, it will look to delay the onset of any endpoint, extending the years in which subjects remain in good health - their healthspan.

In a retrospective 2014 analysis of 78,000 adult type 2 diabetics in their 60s, those who took metformin lived longer, on average, than healthy controls of the same age. This has led a growing body of doctors beginning to prescribe the drug off-label, so that their patients may benefit from its purported anti-aging effects. Such widespread speculation demands deeper scientific investigation. It is TAME's composite primary endpoint, created with the cooperation of the FDA, that excites Barzilai and his colleagues. They hope that Big Pharma will use it to develop drugs with even more powerful anti-aging effects.


Attempting a Unified View of Aging and Loss of Regenerative Capacity

Today's open access paper from the AgeX Therapeutics folk discusses a conceptual framework for looking at aging and loss of regeneration in a unified way across: (a) evolutionary differences between highly regenerative lower species such as hydra and less regenerative higher species such as mammals, (b) the loss of regenerative capacity over the course of embryonic development, and (c) the loss of regenerative capacity that occurs with aging in individuals. It covers a lot of ground, and even the summaries could do with a shorter summary.

In essence this all ties back to the work being done at AgeX Therapeutics and elsewhere on the potential uses of induced pluripotency to produce regenerative therapies. The discovery that cells can be reprogrammed into what are essentially embryonic stem cells, known as induced pluripotent stem cells, was made a little over a decade ago. One of the most interesting outcomes of this process is that various markers of age found in the cells in old tissue are reversed. Epigenetic decorations characteristic of age are removed. A number of groups are working on ways to very carefully induce reprogramming-like outcomes in cells in the body in order to repair mitochondrial function and restore more youthful behavior.

This clearly cannot fix everything. It won't reverse stochastic nuclear DNA damage, for example. Further, since youthful cells cannot clear many of the forms of persistent metabolic waste that accumulate in and around long-lived cells, we should not expect this to greatly impact cross-linking or issues with dysfunctional lysosomes. We do know that mitochondrial dysfunction is very important in aging, however. It is implicated in the progression of many age-related conditions, particularly those of energy-hungry tissues such as the brain and muscles. It is worth chasing approaches that might effectively restore lost mitochondrial function. The major caveat here is cancer, of course. Methods of inducing pluripotency must be accomplished with great care.

Toward a unified theory of aging and regeneration

The advent of cell biology in the 19th century led to August Weismann's insightful hypothesis that heredity is transmitted by cells belonging to an immortal germ line, and that in most cases, the evolution of complex somatic cells and tissues is associated with a loss of immortal regeneration (somatic restriction) that results in aging. Thus, he correctly predicted the limited lifespan of cultured somatic cells due to cellular senescence. In 1957, George Williams hypothesized that aging evolved through a process of antagonistic pleiotropy, where traits benefitting fecundity early in life are selected for even though they simultaneously lead to age-related deterioration later in life. According to an emerging consensus view of the evolution of aging, primitive organisms showing negligible senescence have not traversed the Weismann barrier (loss of immortality and regeneration), while human somatic cell types cross the barrier early in development leading to downstream age-related change.

While certain evolutionarily primitive metazoans, and perhaps some vertebrates, show no evidence of aging, mammals typically show an exponential increase in the risk of mortality with age. Mammalian aging can be viewed as a global developmental program in many cells and tissues in the body wherein somatic cells are progressively restricted in their capacity for immortal regeneration. Accordingly, these steps begin with the repression of the expression of the catalytic component of telomerase TERT resulting in the antagonistic pleiotropic effect of decreased risk of cancer early in life but a finite replicative lifespan of somatic cells leading to cell and tissue aging later in life. Other genes such as TRIM71 also appear to be repressed at or around the time of the pluripotency transition, and the loss of expression may also play a role in restricting cell division. Moreover, subsequent developmental restrictions may also play a role in the cadence of developmental changes that repress tissue regeneration following the completion of organogenesis and subsequent growth. In summary, widespread gene expression changes, like TERT repression, occur early in the life cycle, in many tissues within the body, and these early changes may have an antagonistic pleiotropic effect later in life leading to tissue disrepair associated with aging.

Increasingly the theoretical framework underlying modern aging research is that progressive developmental transitions occur early in the life cycle that impact tissue regeneration and therefore aging in the body. The theory of somatic restriction highlights the dichotomy of the immortal regenerative potential of the germ-line compared to the terminal mortal phenotype of most differentiated somatic cell types. The theory posits that somatic restriction occurs progressively in stages (pluripotency to differentiating embryo, embryo to fetal, fetal to neonate, and neonate to fully grown adult) and that many of these transitions occur globally in multiple organ systems. This conceptual framework provides a context for more detailed analytical studies of developmentally-regulated molecular pathways that were selected for reproductive fitness early in the life cycle, but result in homeostatic decline and failure of organ systems in aging adults (antagonistic pleiotropy). We conclude that modern molecular approaches to regenerative medicine such as reprogramming cells to pluripotency or partially reprogramming to induce tissue regeneration effectively reverse most markers of aging and have significant potential for clinical application in aging.

Fat Tissue Surrounds Skeletal Muscle to Accelerate Atrophy in Aging and Obesity

Researchers here show that the fat tissue surrounding skeletal muscle that is observed in older and obese individuals contributes to declining muscle mass and strength. The most compelling evidence arises from transplantation of fat tissue between mice, showing that it produces harmful effects. The researchers further suggest that cellular senescence is an important factor in this process, which dovetails nicely with what is known of the way in which excess visceral fat tissue accelerates aging. The presence of larger than usual amounts of visceral fat increases the number of lingering senescent cells in the body, and senescent cells broadly disrupt tissue structure and function via their inflammatory signals. The accumulation of senescent cells with age is now accepted as a contributing cause of aging, and an energetic industry aiming to produce senolytic therapies capable of selectively destroying these cells is presently in its initial stages of growth.

Sarcopenia due to loss of skeletal muscle mass and strength leads to physical inactivity and decreased quality of life. The number of individuals with sarcopenia is rapidly increasing as the number of older people increases worldwide, making this condition a medical and social problem. Some patients with sarcopenia exhibit accumulation of peri-muscular adipose tissue (PMAT) as ectopic fat deposition surrounding atrophied muscle. However, an association of PMAT with muscle atrophy has not been demonstrated.

Here, we show that PMAT is associated with muscle atrophy in aged mice and that atrophy severity increases in parallel with cumulative doses of PMAT. We observed severe muscle atrophy in two different obese model mice harboring significant PMAT relative to respective control non-obese mice. We also report that denervation-induced muscle atrophy was accelerated in non-obese young mice transplanted around skeletal muscle with obese adipose tissue relative to controls transplanted with non-obese adipose tissue.

Notably, transplantation of obese adipose tissue into peri-muscular regions increased nuclear translocation of FoxO transcription factors and upregulated expression of FoxO targets associated with proteolysis (Atrogin1 and MuRF1) and cellular senescence (p19 and p21) in muscle. Conversely, in obese mice, PMAT removal attenuated denervation-induced muscle atrophy and suppressed upregulation of genes related to proteolysis and cellular senescence in muscle. We conclude that PMAT accumulation accelerates age- and obesity-induced muscle atrophy by increasing proteolysis and cellular senescence in muscle.


Senescent Cells Mediate Much of the Pulmonary Dysfunction Generated by Smoking

Cells become senescent in response to a toxic, damaging environment. This is a first line of defense against the possibility of cancer. Senescent cells cease replication and begin to secrete a potent inflammatory mix of signals that usually serves to attract immune cells to destroy them, if they don't manage to self-destruct via their own programmed cell death processes. Unfortunately, the immune system becomes ever less functional with age, and thus lingering senescent cells will accumulate in ever greater numbers. This is probably why many of the progressive lung conditions arising from a toxic environment, such as that produced by smoking, tend to arise at a later age.

Researchers here show that a sizable fraction of the pulmonary dysfunction arising from smoking is mediated by the actions of senescent cells in lung tissue, which in turn suggests that senolytic therapies presently under development for age-related diseases will greatly reduce the consequences of smoking and other forms of particulate exposure. Not that is will ever make it smart to stab yourself repeatedly, just because you know that hospital staff can patch up the injury.

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the United States, and can be characterized as a disease of accelerated pulmonary aging. Characteristics of COPD include inflammation, tissue remodeling, and emphysematous alveolar destruction, leading to enlarged air spaces with less surface area capable of gas exchange. Lung exposure to contaminants and pollutants are risk factors for COPD, including cigarette smoking (CS). Aside from smoking cessation, no therapeutic intervention has been identified and research continues to investigate the molecular mechanisms driving disease progression.

Many of the pathological processes identified in COPD are mediated by CS, including altered homeostatic apoptosis proliferation, production of extracellular matrix (ECM)-degrading proteases and oxidative stress, as well as telomere dysfunction, leading to the activation of the DNA damage response pathway and ultimately cellular senescence. Senescent cells produce and secrete numerous harmful pro-inflammatory and degrading mediators, collectively called the senescence-associated secretory phenotype (SASP). SASP proteins have been shown to be upregulated in pathologies related to accelerated aging and are known to perpetuate inflammation and tissue remodeling in COPD. Development of effective therapeutics to combat senescent cells may provide clinical benefit.

A universal marker for cell senescence does not exist but most senescent cells express p16 (p16ink4A), a cell cycle inhibitor that targets cyclin-dependent kinases (CDKs) and is important in wound healing and tumor suppression. Removal of p16+ senescent cells has been shown to be an efficient way of extending healthspan and reversing senescence-associated pathologies. In the current study, we hypothesized that p16 plays a role in the pathological processes associated with smoking and COPD, and that deletion of p16 protects the lung from the development of emphysematous-like tissue remodeling. We examined human lung tissue from COPD patients and normal control subjects, and found a substantial increase in p16-expressing alveolar cells in COPD patients. Using a transgenic mouse deficient for p16, we demonstrated that lungs of mice lacking p16 were structurally and functionally resistant to CS-induced emphysema due to activation of IGF1/Akt regenerative and protective signaling.


Greater Reductions in Blood Pressure in Hypertensive Patients Further Reduce Stroke Risk

The data reported in this study can be added to the considerable weight of prior evidence showing that greater sustained reductions of blood pressure in hypertensive patients is better for long term health. Blood pressure should be lowered more aggressively than has been the case in the past, in other words. This is old news in some respects. The medical community has already adjusted its recommendations in recent years, reducing the pressure thresholds at which blood pressure is considered harmful and a risk to future health.

Raised blood pressure, hypertension, is very influential on the trajectory of age-related disease. It speeds up the development of atherosclerosis, and makes stroke and heart attack due to rupture of atherosclerotic plaques more likely. It causes a raised rate of rupture in small blood vessels, producing microbleeds that harm delicate tissues in the brain, kidney, and elsewhere. The size of these effects is large enough that forcing a reduction in blood pressure without addressing any of the underlying dysfunction that causes hypertension can still produce benefits.

The better path forward, however, would be to address the causes. This approach should be easier, in sense of being more efficient, more cost-effective, and also produce more extensive benefits by reducing the impact of all of the other problems that those underlying causes produce. Damage to tissues never has just one consequence. What causes hypertension? To a first approximation, this is a problem of stiffening of blood vessels. As blood vessels fail to contract and relax appropriately, the feedback mechanisms controlling blood pressure become distorted, resulting in hypertension.

Why do blood vessels stiffen? Because of cross-linking in the extracellular matrix of blood vessel walls, changing its structural properties, particularly elasticity, and separately because of loss of elastin in the extracellular matrix. Because senescent cells and other sources of chronic inflammation lead to calcification of blood vessel tissue, as well as dysfunction in the smooth muscle cells responsible for constriction. Those smooth muscle cells are further hampered by mitochondrial dysfunction, as illustrated by the point that ways of boosting mitochondrial activity reduce blood pressure in older individuals. There is never just one cause, but all of these causes can in principle be repaired. We just need to build the rejuvenation biotechnologies to do it.

Effect of Standard vs Intensive Blood Pressure Control on the Risk of Recurrent Stroke

In 2010, the absolute number of people with a first stroke in the world was 16.9 million, and the number with stroke-related deaths was 5.9 million. Therefore, prevention of primary and secondary stroke is a priority. Elevated blood pressure (BP) is the most relevant and prevalent risk factor for stroke. Reduction in BP is the most effective intervention to prevent both primary and secondary strokes. In clinical trials for primary prevention of cardiovascular events, including stroke, the lower the better seems acceptable for stroke prevention in hypertensive patients, with less than 115 mm Hg suggested as the optimum target level of systolic BP.

After a stroke, lowering BP in the chronic stage reduced the rates of recurrent stroke among both hypertensive and nonhypertensive patients in the Perindopril Protection Against Recurrent Stroke Study (PROGRESS). A post hoc analysis of the PROGRESS suggested that the optimum target level of systolic BP for the prevention of recurrent stroke is less than 120 mm Hg. In the Secondary Prevention of Small Subcortical Strokes (SPS3) randomized trial, the BP target was first evaluated in patients with recent stroke. The trial randomly assigned those with lacunar stroke to a systolic BP target of 130 to 149 mm Hg or less than 130 mm Hg, and the authors showed that the use of a systolic BP target less than 130 mm Hg is likely to be beneficial, especially for the prevention of hemorrhagic stroke.

A recent meta-analysis demonstrated that strict and aggressive control of BP with achieved mean systolic and diastolic BP levels less than 130 mm Hg and less than 85 mm Hg, respectively, seemed to be beneficial for secondary prevention. In primary prevention, the Systolic Blood Pressure Intervention Trial (SPRINT) proved the benefit of aggressive BP control, demonstrating that targeting a systolic BP less than 120 mm Hg resulted in lower rates of major cardiovascular events compared with less than 140 mm Hg. Although a pooled analysis of three studies (3632 participants) comparing different systolic BP targets suggested that intensive BP lowering reduced the rate of recurrent stroke, no clinical trials to date have tested the effect of such aggressive BP lowering for secondary stroke prevention.

In the Recurrent Stroke Prevention Clinical Outcome (RESPECT) Study, we herein tested the hypothesis that targeting intensive BP lowering of systolic and diastolic blood BP less than 120 mm Hg and less than 80 mm Hg, respectively, reduces the rate of stroke recurrence compared with a standard BP-lowering regimen. In this randomized clinical trial that included 1263 patients with a history of stroke, intensive blood pressure control to less than 120/80 mm Hg tended to reduce stroke recurrence compared with standard blood pressure control (less than 140/90 mm Hg). When this finding was pooled with the results of prior trials of intensive blood pressure control for secondary stroke prevention in an updated meta-analysis, intensive blood pressure treatment significantly reduced stroke recurrence by 22%.

Work on Senolytic Rejuvenation Therapies Begins to Attract More Mainstream Notice

This popular science piece on the development of senolytic therapies capable of clearing harmful senescent cells from aging tissues is a cut above the average. It is important to see more publicity for this line of work. Not because it will aid the industry, but because the more attention that is given to the field, the faster that existing senolytic treatments such as the dasatinib and quercetin combination will become available through off-label prescription and physician networks. Tens of millions of patients with inflammatory age-related diseases caused in part by senescent cells, and the many cancer survivors with high burdens of senescent cells due to chemotherapy, and diabetics whose condition is mediated by senescent cells, and the obese whose visceral fat tissue spurs cellular senescence might benefit in the US alone, if they only knew that senolytics exist today.

The choice on whether to try now or wait for more human data for dasatinib and quercetin (or fisetin, or piperlongumine, or other easily obtained senolytics) should be one that people are permitted to make, not one they remain ignorant of because nobody bothered to tell them that it exists. My one complaint about the content of this article is that the author does conspicuously fail to mention that it is possible to obtain access to the first senolytic treatments today, at very low cost, and that older people in the self-experimentation community are indeed choosing to do this.

Imagine if instead of a pill you could take to live for ever there was a pill that could push back the ageing process - a medicine that could stave off the frailty, osteoarthritis, memory loss, macular degeneration, and cancers that plague old age. It could happen, with the science of senolytics: an emerging - and highly anticipated - area of anti-ageing medicine. Many of the world's top gerontologists have already demonstrated the possibilities in animals and are now beginning human clinical trials, with promising results. If the studies continue to be as successful as hoped, those who are currently middle-aged could become the first generation of oldies who are youthful for longer - with a little medical help.

Researchers are at work on senolytics, a branch of medicine that targets senescent cells; the various faulty cells that have been identified as instrumental in our eventual demise. These so-called "zombie" cells linger and proliferate as we age, emitting substances that cause inflammation and turn other healthy cells senescent, ultimately leading to tissue damage throughout the body. In 2011 a team showed that "using a genetic trick to get rid of these senescent cells can significantly improve health and lifespan" in prematurely aged mice. In 2016, the same group achieved similar results in naturally aged mice, releasing an arresting image of two elderly rodents born of the same litter. The one cleared of its senolytic cells seems spry and glossy, while its sibling is shrunken, greying and looks its age.

A new company, called Unity Biotechnology, was formed to raise funds to develop medicine that could safely clear zombie cells from the human body. Trials in senolytics are initially targeting specific conditions such as age-related macular degeneration, glaucoma, and chronic obstructive pulmonary disease (which includes emphysema). Most are in the fledgling stages, working on rodents or human tissue in petri dishes, although in February a small early human trial showed an improvement in the distance patients were able to walk. Also this year, a pre-clinical pilot trial for injecting a senolytic drug into the knees of people with osteoarthritis showed promising, if mixed results. It is hoped that, eventually, there will be a number of senolytic drugs that could potentially target different senescent cell types, but currently much of the research has involved a combination of a leukaemia drug called dasatinib and quercetin, a polyphenol common in plants.

Senolytics are particularly exciting because "they seem to still work very late in life. So it will be possible to study more quickly whether they actually work in humans, and they are applicable to people already at the end of their lives." In theory at least, it should prove impossible to build up a resistance to the drugs, "because senescent cells cannot proliferate". Even more importantly, there is significant data to show "that you don't have to treat these patients every single day. You just treat them once a week or once a month. Intermittent treatment is more than enough to have huge benefits." These aren't the only potential added benefits. Senescent cells "play a big role after cancer treatment", developing as a result of chemotherapy and radiation therapy. "If senolytics can be used to help eliminate the damaged cells before they can spread, a detrimental side-effect of cancer treatment could be alleviated."


Destroying CD163 Tumor Associated Macrophages Allows the Immune System to Better Attack a Cancer

Cancers tend to subvert portions of the immune system into aiding and protecting growth of tumors. The innate immune cells known as macrophages are involved in growth and regeneration, and populations of macrophages resident in tumors become a part of the cancer process. Some of these macrophages have clear surface markers, and can thus be targeted for destruction. Researchers here demonstrate that doing this allows the rest of the immune system to more aggressively attack a tumor. This class of approach may turn out to be quite effective when combined with other forms of immunotherapy that are focused on making T cells more aggressive and capable of destroying cancerous cells.

A new form of immunotherapy that has so far been tested on mice makes it probable that oncologists in the future may be able to treat some of the patients who are not responding to existing types of immunotherapy. Instead of attacking the cancer cells directly, the new technique target and remove a subtype of immune cells known as macrophages, after which the immune system begins to attack the cancer. "We've studied what happens to the tumour when it is exposed to targeted treatment that removes precisely ten per cent of the macrophages that are supporting the cancer tumour instead of fighting it. The most important result is that the depletion of this specific type of macrophage causes the tumour to shrink, which is triggered by a subsequent mobilisation of new macrophages and, ultimately, also an activation of T cells which attack the tumour."

The type of macrophages which the researchers have removed express a specific receptor, CD163, on the cell surface. Unlike other macrophages, these are known to have an undesirable effect in connection with cancer. Instead of recognising cancer cells as unwanted tissue, the macrophage sees the tumours as normal tissue that needs help with regeneration. It is also widely recognised that survival rates are worse if there are many macrophages that express the CD163 receptor in the tumour.

"Our study suggests that the macrophages we're hitting function as a kind of 'peacekeeping' force that keeps the 'attackers' away. When the peacekeeping macrophages in the tumour are removed, the attackers can instead be mobilised, after which the T cells and a number of other macrophages collaborate to attack the tumour. What is interesting is that the whole thing happens by itself as soon as we remove the tenth of the macrophages that express CD163, and that these appear to want to 'decide' which immune cells can be allowed to get into and out of the tumour."


Inhibiting TGFß Receptors Reduces Chronic Inflammation and Plaque in Atherosclerosis

Atherosclerosis involves the development of lipid deposits, called plaques, in blood vessel walls. Plaques narrow and weaken those vessels, ultimately producing the inevitable structural failure of a stroke or heart attack. Perhaps a sixth of humanity dies because of atherosclerosis, but means to treat the condition are so far only capable of somewhat slowing it down, with little reversal of existing plaque. Most approaches, such as statin drugs, focus on reducing the level of lipids in circulation in the bloodstream.

Why does a reduction of blood lipids work to slow atherosclerosis? Atherosclerosis is a condition of dysfunctional macrophages. The immune cells called macrophages are responsible for clearing lipid deposits from blood vessel walls. Where cells become disturbed by the presence of lipids, they secrete inflammatory signals calling for assistance. Macrophages arrive and set to work to ingest the lipids and hand them off to HDL particles in the bloodstream that can carry lipids to the liver for excretion. This all works quite well in youth. But with age, an ever greater fraction of lipids become oxidized in ways that macrophages cannot cope with. Macrophages become distressed, inflammatory, and die, adding their debris to a growing plaque. Their inflammatory signals attract ever more macrophages, in a feedback loop that accelerates the condition. When blood lipids are globally reduced, so are the problem oxidized lipids to the same degree, putting that much less stress on macrophage populations. But it is far from enough to cure the condition.

In the research noted here, scientists target TGF-β, an important signaling molecule. Of note, a sizable fraction of distressed macrophages are in fact senescent cells. Cellular senescence is an inflammatory state that cells adopt in response to damage or stress, and senescent cells secrete signals that encourage other cells to become senescent as well. TGF-β is prominently involved in the signaling produced by senescent cells, and it is plausible that sabotaging it can help to take some of the pressure off in the stressed environment of plaque-ridden blood vessel walls, in much the same way as reducing the input of oxidized lipids can take some of the pressure off. The degree to which it will be effective is something of an open question until tried in humans, however, as past lines of research into therapies for atherosclerosis have typically demonstrated quite poor correlations in reversal of plaque buildup between mouse models and humans.

Study offers promising approach to reducing plaque in arteries

Current treatments for plaque and hardened arteries, a condition known as atherosclerosis, can slow but not improve the disease. Experts believe that may be due to ongoing inflammation in blood vessels. To understand the factors contributing to this inflammation, the research team focused on a group of proteins, called transforming growth factor beta (TGFß), that regulates a wide range of cells and tissues throughout the body.

Using cultured human cells, the researchers discovered that TGFβ proteins trigger inflammation in endothelial cells - the cells that form the inner lining of artery walls - but not in other cell types. With a technique called single cell RNA-seq analysis, which measures the expression of every gene in single cells, they then showed that TGFβ induced inflammation in these cells in mouse models. This finding was notable because TGFβ proteins are known to decrease inflammation in other cells in the body. The researchers also showed that when the TGFβ receptor gene is deleted in endothelial cells, both the inflammation and plaque in blood vessels are significantly reduced.

To test this approach as a potential therapy, the team used RNAi to disrupt TGFß receptors. To deliver the drug only to endothelial cells in the blood vessel walls of mice, they employed nanoparticles. This strategy reduced inflammation and plaque as effectively as the genetic technique. The findings identify TGFß signaling as a major cause of chronic vessel wall inflammation, and demonstrate that disruption of this pathway leads to cessation of inflammation and substantial regression of existing plaque.

Endothelial TGF-β signalling drives vascular inflammation and atherosclerosis

Atherosclerosis is a progressive vascular disease triggered by interplay between abnormal shear stress and endothelial lipid retention. A combination of these and, potentially, other factors leads to a chronic inflammatory response in the vessel wall, which is thought to be responsible for disease progression characterized by a buildup of atherosclerotic plaques. Yet molecular events responsible for maintenance of plaque inflammation and plaque growth have not been fully defined.

Here we show that endothelial transforming growh factor β (TGF-β) signalling is one of the primary drivers of atherosclerosis-associated vascular inflammation. Inhibition of endothelial TGF-β signalling in hyperlipidemic mice reduces vessel wall inflammation and vascular permeability and leads to arrest of disease progression and regression of established lesions. These proinflammatory effects of endothelial TGF-β signalling are in stark contrast with its effects in other cell types and identify it as an important driver of atherosclerotic plaque growth and show the potential of cell-type-specific therapeutic intervention aimed at control of this disease.

Frailty as a Manifestation of Oxidative Stress

Oxidative stress is the name given to the presence of an overly large number of oxidative molecules in cells and tissues, a state that results in damage to protein machinery and degraded function as chemical reactions take place at a faster pace than altered proteins can be replaced. Oxidative stress is a feature of aging, resulting from mitochondrial dysfunction and processes related to chronic inflammation, among other issues. This open access paper discusses oxidative stress in connection with age-related frailty, but is non-committal on where in the chain of cause and consequence, from root causes to final manifestations of aging, oxidative stress is to be found. This is a problem in the field: without some view on which causes result in which consequences in aging, how to steer the research community towards the exploration of effective therapies, those that address causes rather than patching over consequences?

The free radical theory of aging connected oxidative stress with the aging process and aging-related diseases. Although this theory failed to completely explain the aging process, the prominent role of oxidative damage in the decline of function coursing with aging in different tissues is widely accepted. An imbalance between pro-oxidant and antioxidant species would result in oxidative molecular and cellular damage. However, despite their well-known deleterious role, it is now recognized that reactive oxygen species (ROS) are key physiological signaling molecules with regulatory functions. Physiological elevation of ROS generates responses that contribute to cellular hormesis while unmodulated excessive amount of ROS is what results in oxidative damage of molecular and cellular structures. In fact, adequate ROS signaling induces endogenous defense mechanisms and mitohormesis and would explain some contradictory adverse clinical outcomes obtained with antioxidant supplementation.

Oxidative stress has been proven to be associated with age-related diseases. In fact, oxidative stress is related to unsuccessful aging outcome rather than to the aging process by itself. This led us to hypothesize that, as a common background, oxidant injury contributes to functional decline in different tissues and organs and, depending on resilience of these systems, specific clinical alterations are manifested. For instance, specific isolated age-related exhaustion of functional reserve in brain would lead to cognitive impairment while dysfunctional kidney could result in chronic kidney disease, dysfunctional cardiovascular system in cardiovascular disease or dysfunctional lung in chronic obstructive pulmonary disease. In contrast, frailty status would involve a multisystemic failure that results in a condition prone to disability and mortality.

Although the association of frailty and sarcopenia is consistent, the fact that sarcopenia is absent in a significant proportion of frail subjects suggests that frailty and sarcopenia are related but distinct phenotypes of aging. We might consider sarcopenia as a clinical manifestation related to skeletal muscle dysfunction where oxidative stress seems to play a key role. This does not mean that the frailty phenotype in the absence of sarcopenia is unrelated to oxidative stress. In fact, aging-related diseases that could contribute to frailty development share oxidative stress as a common factor in their pathophysiological background. In this sense, there is substantial evidence of the important role played by ROS in the context of unsuccessful aging in organs and systems outside skeletal muscle, including vascular system, kidney, lung, metabolism, and nervous system.

It is important to highlight that aging-related diseases that favor the manifestation of frailty phenotype should not be considered isolated entities but interconnected clinical manifestations with multidirectional relationships and common pathophysiological environments such as oxidative damage. Thus, oxidative stress-related multisystem dysfunction could result in the performance deficit associated to frailty phenotype either including or not sarcopenia phenotype. Mitochondrial dysfunction related to oxidative stress is a key event in this process that affects skeletal muscle but also other tissues promoting the development of age-related diseases and frailty.


Pressure Damage to Capillaries and Surrounding Cells in the Brain as a Contributing Cause of Cognitive Decline

Progressive arterial stiffness with age causes hypertension, a state of chronically raised blood pressure, which in turn damages sensitive tissues in the brain and other organs. Over time that means a loss of function and cognitive decline. Researchers here suggest that even without the increase in blood pressure, stiffness in larger blood vessels will redistribute pressure in a way that will harm cells near to smaller capillary vessels. What causes arterial stiffening? A combination of damage and dysfunction such as, for example: persistent cross-links degrade elasticity in the extracellular matrix of blood vessel walls; senescent cells and the chronic inflammation that they cause creates calcification of tissue, as well as poor function of smooth muscle tissue responsible for blood vessel constriction and dilation; mitochondrial dysfunction in smooth muscle cells also contributes.

The fact that human memory is deteriorating with increasing age is something that most people experience sooner or later, even among those who avoid diseases such as Alzheimer's. Similarly, a connection between the ageing of the brain and the body is well known. However, the exact nature of this association is not known. Researchers have created an explanatory model that starts with the heartbeat, and carries through the largest arteries in the body all the way to the finest vessels in the brain. An important feature of the model is that it provides a rationale why some cognitive processes may be particularly at risk for the proposed mechanism.

As the human body ages, large arteries, such as the aorta, stiffen and lose a large portion of their ability to absorb the pressure increase generated as the heart ejects blood into the arteries. Such pressure pulsatility is instead transmitted to smaller blood vessels, for example those in the brain. The smallest blood vessels in the brain, the capillaries, are subjected to an increased stress that causes damage to cells within and surrounding the capillary walls. These cells are important in the regulation of the capillary blood flow. If the smallest blood vessels are damaged, this is detrimental to the ability to increase the blood supply to the brain when coping with demanding cognitive processes.

According to the researchers' model, the hippocampus in the brain is particularly vulnerable. The structure in that part of the brain is important for the episodic memory, that is, the ability to remember events from the past. The vulnerability of the hippocampus relates to the fact that it is located close to the large vessels and thus is exposed to the increased load early in the chain. In a young and healthy person, the pulsations are soft, but in an ageing person the pulsations can be so powerful that they affect the brain tissue and can damage the blood supply to memory processes.


Vascular Endothelium in Bone can be Targeted to Treat Osteoporosis in Mice

Osteoporosis is the name given to the characteristic loss of bone mass and strength that occurs with age. In its later stages it becomes very dangerous, and bones can fracture even under normal load. Bone is a dynamic tissue, constantly restructured and rebuilt throughout life by the actions of osteoblasts responsible for creating the molecular structure of bone and osteoclasts responsible for breaking down that structure. At root, osteoporosis is an easy problem to visualize: the balance of activity slowly and systematically tips towards osteoclasts. The complexity of the problem lies in how and why that imbalance happens, and thus what might be the best strategy for the development of treatments. At present comparatively little can be done for patients, but that will hopefully change for the better in the years ahead.

Today's research materials discuss a new addition to existing potential approaches that might restore the balance between osteoblasts and osteoclasts, those that have been demonstrated in the laboratory in recent years. It is interesting in that the scientists involved don't yet know exactly why their basis for therapy works in animal models. That said, I think it fair to say that it probably falls into the category of increasing the activity of osteoblasts in order to restore the balance, while having all the appearance of a complex and indirect set of mechanisms that will take years to fully understand. Our biology is packed with complex and indirect mechanisms, which is one of the reasons why progress is always slower than we'd like.

Molecule Promoting Blood Vessel Growth in Bone Represents New Target for Osteoporosis Drugs

Researchers have shown that a substance, which is best known for spurring nerve growth, called SLIT3, both reversed the bone-weakening effects of osteoporosis and helped fractures heal when administered in mice. The research effort could fuel drug development efforts targeting the SLIT3 pathway in humans, enabling a new approach for blood vessel-directed therapy to treat bone loss, persistent fractures, and fragile bones. Existing drugs for osteoporosis work in one of two ways: Either they block the cells that destroy bone or they promote bone formation by cells called osteoblasts. "But only those promoting new bone formation will help you actually heal a bone fracture. Our findings have potentially demonstrated a third category: drugs that target blood vessel formation within bone, prompting new bone to form."

Researchers have investigation the cellular causes of osteoporosis in an effort to promote bone growth. Prior research using mice genetically engineered to lack an adaptor protein known as SHN3 showed that its absence conferred high bone mass. Building on that discovery, researchers decided to examine the resulting changes in bone blood vessels. They were surprised to find that osteoblasts secreted unchanged amounts of almost all known factors promoting blood vessel growth, but SLIT3 levels rose significantly. And when the mice were genetically altered to delete SLIT3, they exhibited low bone mass. "We next asked if we could use SLIT3 to treat mice with skeletal disease, especially osteoporosis and fracture healing. When we gave the rodents SLIT3, it reversed their osteoporosis and made their fractures heal faster and stronger. To my knowledge, this is the first example that we can develop a drug to treat bone disease in mice not by targeting the bone-forming cells, but instead by targeting special types of blood vessels that exist in bone."

Targeting skeletal endothelium to ameliorate bone loss

Recent studies have identified a specialized subset of CD31+ vascular endothelium that positively regulates bone formation. However, it remains unclear how endothelial tissue levels of these cells are coupled to anabolic bone formation. Mice with an osteoblast-specific deletion of Shn3, which have markedly elevated bone formation, demonstrated an increase in the CD31+ subset of endothelial cells. Transcriptomic analysis identified SLIT3 as an osteoblast-derived, SHN3-regulated proangiogenic factor. Genetic deletion of Slit3 reduced the CD31+ subset population in the endothelium, resulted in low bone mass because of impaired bone formation, and partially reversed the high bone mass phenotype of Shn3-/- mice.

This coupling between osteoblasts and a subset of CD31+ endothelial cells is essential for bone healing, as shown by defective fracture repair in SLIT3-mutant mice and enhanced fracture repair in SHN3-mutant mice. Administration of recombinant SLIT3 both enhanced bone fracture healing and counteracted bone loss in a mouse model of postmenopausal osteoporosis. Thus, drugs that target the SLIT3 pathway may represent a new approach for vascular-targeted osteoanabolic therapy to treat bone loss.

Potentially Damaging Ossified Particles Discovered in the Aging Bloodstream

Calcification is the inappropriate deposition of minerals into tissue, altering structural properties to cause a loss of elasticity. It is a feature of the aging cardiovascular system, in part caused by inflammatory signals and other harmful activities of senescent cells. The growing numbers of senescent cells in old tissues cause changes in the behavior of other cell populations, which leads to greater mineralization of tissues that should normally be flexible. Researchers here uncover another consequence of this process, which is the presence of what are effectively bone particles in the bloodstream. These particles are large enough to cause a variety of damage to blood vessels, and while the size of this effect is unknown, this adds to the existing set very good reasons to try to prevent and reverse calcification in aging tissues.

Blood vessels within bone marrow may progressively convert into bone with advancing age. Examination of these vessels led to the discovery of bone-like particles in the peripheral circulation. The findings suggest that ossified particles may contribute to diseases such as vascular calcification, heart attack, stroke, and inadequate blood supply to the limbs. In fact, some of the ossified particles are large enough to clog the smallest blood vessels in the vascular tree.

Approximately 610,000 people die each year from a heart disease-related event, making it the leading cause of death for both men and women in the United States, according to the Centers for Disease Control and Prevention. Vascular calcification is a common characteristic and risk factor for morbidity and mortality. These bone-like particles are potentially more dangerous because of their sharp edges. "Some of the ossified particles have sharp tips and edges that could damage the lining of blood vessels. This damage could initiate events leading to atherosclerosis, which can restrict blood flow over time. When looking for etiologies related to vascular calcification, heart attack and/or stroke, perhaps we should consider if and how ossified particles contribute to these diseases. We will examine these possibilities."


Declines in Limb Muscle Mass Correlate with Higher Mortality in Late Life

Given that resistance training is shown to reduce mortality in older individuals, it makes sense that we would see the opposite effect when looking at low muscle mass in limbs. Skeletal muscle isn't an inert tissue, being quite involved in insulin metabolism, for example, and exercise has all sorts of interesting effects on the operation of metabolism, such as upregulation of beneficial cellular stress response mechanisms. Aging is associated with a progressive loss of muscle mass and strength, with the loss of stem cell activity being a leading cause. This ultimately results in frailty and the condition of weakness known as sarcopenia. In our modern societies of sedentary convenience, this loss is much faster that it would otherwise be if people were more active, and hence the point that resistance training improves matters from the present baseline. That is only the case because most older people do not undertake any sort of effort to maintain muscle mass and strength.

Evaluating body composition, especially appendicular muscle mass, can be an effective strategy for predicting longevity in people over 65 years of age, according to a new study. The appendicular muscles are the muscles that move the appendages or extremities - the arms and legs. They also play a key role in stabilizing the shoulders and hips. The researchers studied a group of 839 men and women over the age of 65 for approximately four years. They observed that all-cause mortality risk increased nearly 63-fold during the follow-up period in women with low appendicular muscle mass and 11.4-fold in men.

"We evaluated the body composition of this group, focusing on appendicular muscle mass, subcutaneous fat, and visceral fat. We then sought to determine which of these factors could predict mortality in the ensuing years. We concluded that the key factor was the amount of appendicular lean mass." Body composition was determined by dual energy X-ray absorptiometry (DXA), also known as bone density scanning, using a densitometer. The study sample comprised 323 men (39%) and 516 women (61%). The frequency of low muscle mass was approximately 20% for both men and women.

Generally, subjects who died were older, exercised less, and suffered more from diabetes and cardiovascular problems than those who remained alive. In the case of the women who died, they also had decreased BMI. The men who died were more likely to suffer falls. All these variables were fed into the statistical model and adjusted for the end-result to show which body composition factor correlated best with mortality risk. Only low muscle mass was found to be significant in the women, considering the adjustment variables, while visceral fat was also significant among the men.

Menopause-related hormone changes may help explain the difference between men and women. "The rapid and significant transition from a protective estrogenic environment to a deleterious hypoestrogenic environment, which is particularly adverse for the cardiovascular system, may make the protective metabolic role of skeletal muscles, including the production of anti-inflammatory cytokines, more important in the postmenopause period. This hormone change is far less abrupt in men."

In addition to their obvious importance in posture, balance and movement, the skeletal muscles have other functions that are essential to the body. They help regulate blood sugar by consuming energy during contraction and maintain the body temperature by trembling when cold. They also produce messenger hormones, such as myokinase, that assist communication with different organs and influence inflammatory responses. The good news is that sarcopenia is preventable and can even be reversed by physical exercise, especially muscle toning. Attention to protein ingestion is also recommended.