Fight Aging! provides a weekly digest of news and commentary for thousands of subscribers interested in the latest longevity science: progress towards the medical control of aging in order to prevent age-related frailty, suffering, and disease, as well as improvements in the present understanding of what works and what doesn't work when it comes to extending healthy life. Expect to see summaries of recent advances in medical research, news from the scientific community, advocacy and fundraising initiatives to help speed work on the repair and reversal of aging, links to online resources, and much more.
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- Improved Quality Control of Protein Folding Extends Life in Nematode Worms
- Today is Giving Tuesday: if you Favor a Long, Healthy Life for Everyone, then Make a Donation to Support the Work of the SENS Research Foundation
- Arguing for Cellular Senescence to be Significant in the Development of Osteoarthritis
- Support for Impaired Drainage Theories of Alzheimer's Disease
- The Slow Death of the Self that is Produced by the Normal Operation of Human Memory
- Latest Headlines from Fight Aging!
- Hunter-Gatherer Data Used to Evaluate the Effects of Exercise on Long-Term Health
- Comparing Gene Expression Profiles of Mammalian Species in Order to Search for the Determinants of Longevity
- Interleukin-1 Receptor Antagonists as a Stroke Treatment
- Incidence of High Blood Pressure Rises and Spreads, Following Increased Wealth
- Data on the Effects of Follistatin Gene Therapy from BioViva
- Sarcopenia Finally Obtains an ICD Code
- Stem Cell Research and the Treatment of Neurodegenerative Diseases
- Another Group Argues for Alzheimer's Disease to be a Diabetic Condition
- A Reasonable Perspective on Cryonics
- Embryonic Gene Hoxa9 Reactivates with Age to Limit Muscle Stem Cells
Improved Quality Control of Protein Folding Extends Life in Nematode Worms
In the paper I'll point out today, researchers map an efficient form of protein quality control from stem cells and recreate it in somatic cells, producing extended life in nematode worms as a result. Proteins are large, complex molecules, and their correct function depends on the assumption of a precise three-dimensional arrangement after creation, a process known as protein folding. Proteins can and do misfold, however, and in doing so many become actively harmful rather than merely unwanted clutter. A baroque system of chaperone proteins assists in correct folding, as well as identification and removal of misfolded molecules. The presence of misfolded proteins is effectively a form of damage: some of the molecular waste that accumulates with age and contributes to the development of age-related disease consists of misfolded proteins, such as the various forms of amyloid, for example. The gradual failure of cellular recycling systems, such as declining lysosomal function caused by the presence of metabolic waste that is hard for the body to break down, or similar failures in the proteasome, also contribute to rising levels of damaged and dysfunctional proteins. Since aging is nothing more than the accumulation of damage and the reactions to that damage, more efficient operation of chaperone and other quality control systems in cells should slow aging: the less damage there is at any one time, the less of an opportunity that damage has to spread and cause secondary issues. It is probably not a coincidence that increased quality control activity is observed in many of the methods shown to modestly slow aging in laboratory animals, and that some forms of slowing aging cannot work without that quality control boost.
As for any study that extends life in short-lived species in this way, it is worth noting that the life span of short-lived species is far more plastic than that of longer-lived species such as we humans. Where the research community can directly compare methods, such as calorie restriction, exercise, or growth hormone receptor mutation, it is clear that doubling worm life spans or a 40-60% increase in mouse life spans certainly doesn't map to that much of a change in human life span - or even more than just a few years. If it did, we've have noticed by now, as it would leap out of the data on human health and mortality. That researchers don't see that in the data constrains the effects to be fairly small, a handful of years at most. So for my part I believe we should look at this and other similar studies as indicators of importance, not a literal guide to building human therapies. These studies help to point out which forms of age-related molecular damage have the biggest impact, and thus are the highest priority for repair via the methods outlined in the SENS rejuvenation research proposals. It isn't a suggestion to attempt to adopt modified chaperone systems in humans, as that would be a highly inefficient way to proceed. It would likely produce results on a par with exercise or calorie restriction: improved health, modestly slowed aging. That is far less useful than methods of repairing the damage, clearing out all of the misfolded proteins every now and again before they rise to the level of causing real issues. Periodic repair can create rejuvenation if comprehensive enough. In the near term of decades, adjusting biology to run in a different way can only modestly slow aging; it will be a long time indeed before the research community is capable of safely creating a new biology that doesn't age in this way. That is time far better spent on the faster path to working rejuvenation treatments.
Defining immortality of stem cells to identify novel anti-aging mechanisms
With age, somatic cells such as neurons lose their ability to maintain the quality of their protein content. Pluripotent stem cells, on the contrary, do not age and have increased mechanism to maintain the integrity of their proteins. The survival of an organism is linked to its ability to maintain the quality of the cellular proteins. A group of proteins called chaperones facilitate the folding of proteins and are essential to regulating the quality of the cellular protein content. This ability declines during the aging process, inducing the accumulation of damaged and misfolded proteins that can lead to cell death or malfunction. Several neurodegenerative age-related disorders such as Alzheimer's, Parkinson's or Huntington's disease are linked to a decline in protein quality control.
Human pluripotent stem cells can replicate indefinitely while maintaining their undifferentiated state and, therefore, are immortal in culture. This capacity necessarily demands avoidance of any imbalance in the integrity of their protein content. "There is one chaperone system, the TRiC/CCT-complex that is responsible for folding about 10% of all the cellular proteins. By studying how pluripotent stem cells maintain the quality of their proteome, we found that this complex is regulated by the subunit CCT8. Then, we discovered a way to increase the assembly and activity of the TRiC/CCT complex in somatic tissues by modulating this single subunit, CCT8. The increase resulted in prolonged lifespan and delay of age-related diseases of the model organism Caenorhabditis elegans. For this study we combined the results from human pluripotent stem cells and C. elegans, to have both in vitro and in vivo models, providing a more convincing approach. Our results show that expressing CCT8 as the key subunit of the complex is sufficient to boost the assembly of the whole system. It is very interesting that expressing this single subunit is enough to enhance protein quality and extend longevity, even in older animals. One of our next steps will be to test our findings in mice."
Somatic increase of CCT8 mimics proteostasis of human pluripotent stem cells and extends C. elegans lifespan
Human embryonic stem cells can replicate indefinitely while maintaining their undifferentiated state and, therefore, are immortal in culture. This capacity may demand avoidance of any imbalance in protein homeostasis (proteostasis) that would otherwise compromise stem cell identity. Here we show that human pluripotent stem cells exhibit enhanced assembly of the TRiC/CCT complex, a chaperonin that facilitates the folding of 10% of the proteome. We find that ectopic expression of a single subunit (CCT8) is sufficient to increase TRiC/CCT assembly. Moreover, increased TRiC/CCT complex is required to avoid aggregation of mutant Huntingtin protein. We further show that increased expression of CCT8 in somatic tissues extends Caenorhabditis elegans lifespan in a TRiC/CCT-dependent manner. Ectopic expression of CCT8 also ameliorates the age-associated demise of proteostasis and corrects proteostatic deficiencies in worm models of Huntington's disease. Our results suggest proteostasis is a common principle that links organismal longevity with hESC immortality.
Today is Giving Tuesday: if you Favor a Long, Healthy Life for Everyone, then Make a Donation to Support the Work of the SENS Research Foundation
Following the commercial shopping days of Black Friday and Cyber Monday is the day for non-profits and charitable donation, Giving Tuesday. It is a young idea, first announced in 2012, but a great idea, and one that has seen considerable adoption. Of this cluster of marked days, I expect Giving Tuesday to be the cultural phenomenon that will produce the greatest long-term change for the better. Just focusing on support for medical research, it is clear that very few people put any thought into where therapies come from and how progress in medicine happens. Every opportunity to explain to the public at large that the most important early stages of medical research are largely funded by philanthropy is an opportunity to increase that funding and speed progress. Yes, most people will ignore the request for help, but every year the communities focused on research for specific diseases grow. Every year more people realize that we live in the midst of a revolution in biotechnology, and medicine can and will make enormous progress in the decades ahead. In our case the disease is aging: addressing the root causes of aging will, to the extent that it is comprehensive and effective, halt and turn back all of the hundreds of named forms of age-related disease, as well as the frailty and degeneration that is currently thought of as normal.
For Giving Tuesday 2016 I ask you to make a donation to the SENS Research Foundation or Methuselah Foundation, organizations that have done more than any other over the past fifteen years to advance the state of rejuvenation research. They have pushed the scientific community towards developing much more of the basis for therapies capable of repairing the cell and tissue damage that causes aging, and funded many of these programs. They have removed roadblocks and enabled other groups to make significant progress. Indeed, the entire culture of the scientific community has changed over that time, from one in which it was career-threatening to talk about extending human life spans to one in which many researchers talk openly and publish papers on this topic. Now the biggest argument is over how to proceed. That, again, has a lot to do with the years of advocacy carried out by the SENS Research Foundation, Methuselah Foundation, and their allies. Fifteen years ago, next to no work on repair of the causes of aging was taking place. Now there is at least some funded research in every important line of work, and some are well funded indeed. This has come to pass because over this time a great many people have made charitable donations to the SENS Research Foundation and Methuselah Foundation, and those organizations made very good use of that money.
Until the end of 2016, all single donations made to the SENS Research Foundation will be matched, by the generosity of Michael Greve, who has put up a 150,000 challenge fund. Similarly, Josh Triplett, Christophe and Dominique Cornuejols, and Fight Aging! have put up another 36,000 challenge fund that will match the next year of donations for anyone who signs up as a SENS Patron to make monthly donations to the SENS Research Foundation. What are you waiting for?
This is a great time for progress in rejuvenation research and development, and a great time to reinforce that progress. The first class of therapies based on the SENS vision for rejuvenation, clearance of senescent cells, is in active development by a number of startup companies, including Oisin Biotechnologies, seed funded by the Methuselah Foundation and SENS Research Foundation, and UNITY Biotechnology, where the principals have raised more than 100 million to date to bring this therapy to the clinic. Other types of rejuvenation therapy that address other forms of cell and tissue damage are within a few years of that tipping point, given sufficient funding for continued research. Researchers focused on breaking down the cross-links that cause arterial stiffness and loss of elasticity in other tissues have made great strides in building the necessary tools thanks to SENS Research Foundation funding, and are presently engaged in the search for drug candidates. Removal of the amyloids that build up in old tissues is showing progress also in recent years, with a successful trial of clearance of transthyretin amyloid and the first trial in which amyloid-β was cleared in Alzheimer's disease patients. There is much more to tell, but you get the picture. Things are moving, the wheel is turning, and this is in large part due to our support for the SENS Research Foundation and Methuselah Foundation in past years.
We, the everyday philanthropists who dare to dream big, have helped to make these successes possible. We have pushing things past the first, hardest part of the bootstrapping process, and brought the end to frailty and disease in aging that much closer. We light the way, by our participation and advocacy attracting those who are more wealthy and conservative in their donations, and who were waiting for signs of support before stepping in. By donating today to the SENS Research Foundation and Methuselah Foundation, you help to set the foundation for the successes of the 2020s, for the widespread clinical availability rejuvenation therapies that, given the funding, will come to pass in that decade.
Arguing for Cellular Senescence to be Significant in the Development of Osteoarthritis
There are two ways to provide evidence for a specific cellular mechanism to cause a specific age-related disease. The first, the better method, is to remove, block, or work around the mechanism, while changing as few other variables as possible. This is better because it can lead immediately to the development of a therapy if it turns out that the mechanism in question is important. The worse option is to make the mechanism more active, while changing as few other variables as possible, and see if problems happen more rapidly because of that alteration. This is worse because there is always the risk that greater activity in any biological process does cause greater harm, but is nonetheless not actually relevant to aging and age-related disease because that greater activity never happens in the normal course of matters. DNA repair deficiency is a great example of the type. Significant impairment of DNA repair produces damage, dysfunction, and accelerated disease and mortality, but really isn't all that relevant to normal aging. All that this tells us is that it is important that DNA repair functions correctly, in the same way that it is important to breathe, or important that hearts beat and blood flows. There are many ways to cause damage by breaking the operation of our biochemistry - you can hit living organisms with a hammer, for example - but very few of them tell us much about aging and age-related disease.
With that preamble out of the way, today I'll point you to an interesting open access study in which the authors uses the worse of the two methods noted above to provide evidence for senescent cells to contribute to the development of osteoarthritis, a degenerative condition in which joint tissues become inflamed and break down. This is accomplished by transplanting a sizable number of senescent cells into the joints of mice and observing the outcome over a number of months following the transplant. Senescent cells accumulate in our tissues with age, and their presence is certainly a form of damage, with plenty of evidence to link it to the development of age-related disease. Researchers have produced benefits in laboratory animals by selectively destroying senescent cells, and a variety of these approaches are under development as clinical therapies. Given that, the more conditions linked to cellular senescence, the better off we all are. For this particular study, however, the question is whether or not transplanting senescent cells into tissue is a good enough replication of the processes of aging to tell us something, or whether it is just another sophisticated way of causing damage that isn't particularly relevant to aging. The devil is in the details, but having read the details, I'm leaning towards the former position.
Senescent cells cause harm through signaling. A cell becomes senescent and ceases replication in response to reaching the Hayflick limit, or suffering damage, or finding itself in a toxic environment. Most destroy themselves or are destroyed by the immune system, but some linger. Growing numbers of these cells eventually cause serious harm. A senescent cell secretes a mix of inflammatory and other signals that cause harm to surrounding tissue structures and change the behavior of normal cells for the worse. Perhaps a few percent of all cells in our tissues are senescent by the time we are old, but that is more than enough to cause major dysfunction. Since this is largely a signaling problem, it seems fairly reasonable to suggest that researchers could reproduce the effects of senescent cells on aging via transplantation. This would be something like the reverse of the goal of a stem cell transplant, in which the transplanted cells produce benefits largely through signaling. So long as the number of transplanted senescent cells falls within the bounds of what would be expected over the course of normal aging, one can argue that this type of study can be a good, rapid test of the outcomes that cellular senescence produces. In any case, read the paper and see what you think:
Transplanted Senescent Cells Induce an Osteoarthritis-Like Condition in Mice
Osteoarthritis (OA) is one of the leading causes of pain and disability worldwide. It can greatly increase health care costs and reduce quality of life. The key characteristics of age-related OA in humans include damage of articular cartilage with joint space narrowing and degeneration of soft tissues. Age is the leading predictor for developing OA. However, modeling age- or senescence-associated OA, which may be distinct from injury-related OA, in mice has been challenging. So far, no disease-modifying drug has been approved to treat OA other than pain reducers, partly because etiological mechanisms of age-related OA have been poorly understood to date. Potential cellular mechanisms contributing to the development of OA include low-grade inflammation, chondrocyte alteration, mitochondrial dysfunction, loss of glycosaminoglycans, and dysregulated energy metabolism. In addition, a potential contribution by senescent cells has been suggested. Cellular senescence refers to a state of stable arrest of cell proliferation in replication-competent but apoptosis-resistant cells. Senescent cells accumulate with aging in various tissues, including the articular cartilage. One key feature of senescent cells is secretion of an array of pro-inflammatory cytokines, chemokines, and growth factors, termed the senescence-associated secretory phenotype (SASP). The SASP is observed across a number of senescent cell types, including fibroblasts and mesenchymal stem cells. Although mounting evidence suggests that cellular senescence is associated with OA, whether this link is causal remains to be determined.
To test if senescent cells cause an OA-like arthropathy, we injected either senescent or control nonsenescent fibroblasts into the knee joint region of mice. We transplanted seven mice with control cells and seven with senescent cells. Three months after cell injection, senescent and nonsenescent cell-injected knees were evaluated histologically and radiologically to assess articular cartilage and overall joint structure. We found that the senescent cells induced a phenotype with features resembling OA, including articular cartilage erosion, increased pain, and impaired function. We found that Rotarod performance was significantly decreased in the mice injected with senescent cells compared with animals injected with control nonsenescent cells or those that were not injected. In addition, we found that mice injected with senescent cells moved less and traveled shorter distances than mice injected with control nonsenescent cells. To our knowledge, this is the first evidence suggesting that cellular senescence can actually cause OA. Our findings also imply that targeting senescent cells is a promising approach for preventing or treating OA.
This both provides a new model of OA and implies that clearing senescent cells with senolytics or interfering with their pro-inflammatory SASP could be a disease-modifying therapeutic option. A next step will be to test such interventions in our senescent cell-transplanted model. One of the potential mechanisms by which senescent cells could induce an OA-like phenotype is through the SASP. OA is linked to inflammation and immune cells have been found in early stage OA. IL-6, one of the key SASP components, is highly associated with OA progression. We found that the senescent cells we transplanted secreted 20 times more IL-6 than nonsenescent cells. In addition, senescent cells can directly impair progenitor function through the SASP and spread senescence to nearby cells, both of which might contribute to dysfunction of chondrocytes and therefore to OA.
The finding that cellular senescence can drive development of an OA-like state is consistent with the geroscience hypothesis - that fundamental aging mechanisms, of which cellular senescence is one, predispose to age-related disabilities and chronic diseases, such as OA. If correct, this would imply that senescent cell accumulation may not only predispose to OA, but to multiple other age-related conditions, as is increasingly appearing to be the case. We predict that senolytics or SASP inhibitors such as ruxolitinib, which decreases IL-6 secretion and effects by senescent cells and also alleviates the senescent cell-induced stem cell dysfunction caused by TGFβ-related SASP factors, will delay, prevent, or alleviate OA. Consistent with this possibility, we found that senolytics attenuate age-related loss of glycosaminoglycans, a contributor to developing OA, from the intervertebral discs of progeroid mice. Moreover, senolytics are effective when administered periodically, likely because senescent cells do not of course divide and may be slow to re-accumulate once cleared in the absence of a strong continuing insult. We predict that senolytics may have fewer side effects than the anti-inflammatory agents currently used for controlling pain.
Support for Impaired Drainage Theories of Alzheimer's Disease
Alzheimer's disease is associated with the growing presence of solid deposits of misfolded amyloid-β and altered tau protein in the brain. A halo of complex and much debated biochemistry connects these forms of metabolic waste with the dysfunction and death of neurons; it isn't the amyloid or the tau itself, but related molecules and their interactions that cause pathology, arising as a result of the existence of the amyloid and tau. Clearing these unwanted proteins should help to turn back the progression of Alzheimer's, a goal complicated by the fact that many Alzheimer's patients also suffer from other forms of neurodegeneration, such as the vascular dementia that results from hypertension, blood vessel stiffness and structural failure, and many tiny zones of cell death caused by blood vessel failures over the years. Unfortunately in addition to these complications, safely clearing amyloid in the human brain has proven to be very challenging. Most efforts to date have used forms of immunotherapy, and only recently have good results emerged in human trials. The field of the past decade is littered with the remains of failed efforts. Clearance of tau has much further to go in order to arrive at the point of human trials, not having received the same level of attention and funding over the past decade. It is becoming apparent that it will also have to be removed from the brain, however.
Why do amyloid and tau aggregate in the aging brain? There are many competing theories. The brain, its immune system, and its surrounding support structures are enormously complex and only partially understood. In many ways the quest to understand Alzheimer's disease is one and the same with the quest to understand the brain as a whole. A cure for Alzheimer's is the goal that brings in funding for fundamental research into the mechanisms of thought, memory, and aging, as well as details of cellular behavior, inflammation and immunology in the brain, distinctly different and more complicated than elsewhere in the body. One interesting point regarding amyloid-β is that its levels in brain tissue and cerebrospinal fluid are very dynamic. It is constantly created and destroyed, and so the accumulation with age is not a matter of slow and steady creation, but rather results from the interaction and changing nature of numerous processes.
One class of theories seeking to explain increased amounts of amyloid-β with aging postulate a gradual failure in mechanisms of clearance, such as immune activity, since the immune system is responsible for removing many forms of unwanted metabolic waste, or filtration of cerebrospinal fluid by the choroid plexus. Alzheimer's becomes a tertiary consequence at the end of a chain of failures that starts with some form of age-related decline in the effectiveness of clearance of metabolic waste in the brain. Cerebrospinal fluid isn't just filtered, however. Small amounts continually drain away from the brain via a variety of small channels in the head, to be replaced by new fluid generated by the choroid plexus. In recent years some researchers have suggested that this drainage is an important mode of clearance for amyloid and tau, and that the necessary channels becomes impaired due to other forms of age-related damage and change. You might look at the efforts of Leucadia Therapeutics, for example, a startup company funded by the Methuselah Foundation, as they work to prove or disprove this mechanism as a cause of Alzheimer's disease. With that in mind, I noticed the following research today, in which the authors offer further evidence in support of the class of hypotheses that involve impaired cerebrospinal fluid drainage.
Study suggests possible new target for treating and preventing Alzheimer's
The new study examined aquaporin-4, a type of membrane protein in the brain. Using brains donated for scientific research, researchers discovered a correlation between the prevalence of aquaporin-4 among older people who did not suffer from Alzheimer's as compared to those who had the disease. Aquaporin-4 is a key part of a brain-wide network of channels, collectively known as the glymphatic system, that permits cerebral-spinal fluid from outside the brain to wash away proteins such as amyloid and tau that build up within the brain. These proteins tend to accumulate in the brains of some people suffering from Alzheimer's, which may play a role in destroying nerve cells in the brain over time.
The study closely examined 79 brains donated through the Oregon Brain Bank. They were separated into three groups: People younger than 60 without a history of neurological disease; people older than 60 with a history of Alzheimer's; and people older than 60 without Alzheimer's. Researchers found that in the brains of younger people and older people without Alzheimer's, the aquaporin-4 protein was well organized, lining the blood vessels of the brain. However within the brains of people with Alzheimer's, the aquaporin-4 protein appeared disorganized, which may reflect an inability of these brains to efficiently clear away wastes like amyloid beta. The study concluded that future research focusing on aquaporin-4 - either through its form or function - may ultimately lead to medication to treat or prevent Alzheimer's disease.
Association of Perivascular Localization of Aquaporin-4 With Cognition and Alzheimer Disease in Aging Brains
Since 2013, we have defined a brain wide perivascular pathway, termed the glymphatic system, that facilitates the recirculation of cerebrospinal fluid (CSF) through the brain parenchyma and supports the clearance of interstitial solutes including amyloid-β (Aβ) and tau. Perivascular exchange of CSF and interstitial fluid is dependent on the astroglial water channel aquaporin-4 (AQP4), which is localized to perivascular astrocytic endfeet that ensheathe the cerebral vasculature. We demonstrated that perivascular CSF recirculation and Aβ clearance are impaired in the aging mouse brain, impairment that was associated with the loss of perivascular AQP4 localization. Prior studies in postmortem human tissue show that AQP4 is up regulated and that localization of AQP4 to the cerebral vasculature is disrupted in the AD cortex. This suggests that age-related mislocalization of AQP4 may slow glymphatic function and promote protein aggregation and neurodegeneration.
In this study, we assessed AQP4 expression and perivascular localization in human brain samples including individuals of different ages and with different cognitive and neuropathological AD profiles. Expression of AQP4 was associated with advancing age among all individuals. Perivascular AQP4 localization was significantly associated with AD status independent of age and was preserved among eldest individuals older than 85 years of age who remained cognitively intact. When controlling for age, loss of perivascular AQP4 localization was associated with increased amyloid-β burden.
The Slow Death of the Self that is Produced by the Normal Operation of Human Memory
People are terrified of dementia, by the loss of the self that results from the final stages of the accumulation of age-related damage in the brain. Whether this is loss of data or merely loss of access to data, that data being encoded in the structures of neurons and their connecting synapses, depends upon the details along the way. Either option amounts to the same thing for someone in the midst of the condition when there is only faint prospect of therapies arriving soon enough to matter. But if dementia is an asymptotic approach to 100% loss of data, what to make of the fact that we are, on a day to day basis, largely accepting of our normal relationship with the data of the mind, in which we lose 98% of everything that we experience within a few weeks of the event? A week from now you will not remember reading this, nor will there be any trace of what took place in the surrounding minutes before and after. You will have to guess at how you spent your time, what you were thinking, who you were at that moment. We are, every one of us, thin and translucent ghosts of our own history, mere summaries of a rich set of data that is now gone.
Yet we get by. Normal is normal, but that doesn't mean it is good, or that it should go unexamined. To put this another way, there was a person who lived a few decades ago in the UK, and got by. Later, there was another person who came to the US and spent time here, as people do. I know about as much about those individuals as I do about friends of long standing, perhaps just a little more. Yet both of them were me. All of that remains of them, of their richness of data, are the echoes I carry with me now. I have the memories burned in by adrenaline or, to a lesser extent, by sheer boring repetition, but those are just signposts in the mist by this point. Ask me who I was back then, and the answer will be largely extrapolation. Are those individuals dead? Am I so different that such a question makes sense to ask? To what extent is the self burning away and vanishing because we have a poor capacity for remembrance? To what extent is change death, in other words? Here of course I do little more than wave my hands at questions that have been debated at great length in the philosophy community.
Those of us who are generally opposed to the idea of being scanned, uploaded, and copied have the view that a copy of the self is not the self. It is its own separate individual. Individuality stems from the combination of pattern of information and the matter that the pattern is bound to. It isn't clear that, for example, an emulation running in an abstraction layer over computing hardware can be considered a continuous entity, rather than a unending series of nanosecond individuals assembled and then destroyed. In the continuity view of identity, a Ship of Theseus sort of a viewpoint, you are still you even if all your component parts are slowly replaced over time. There is a sizable grey area at the border between small parts and slow replacement, which is fine, and large parts and rapid replacement, which is the same as death. If someone removes half of your brain in one go and replaces it with a hypothetical machine that accepts exactly the same inputs and produces exactly the same outputs where it connects to the remaining brain tissue, I would say that this means that you just died, even though an entity that thinks in the same way as you did continues onward. Conversely, replacing neurons one by one with machines that perform the same functions, and allowing time for each neuron to reach equilibrium with its neighbors, seems acceptable.
Continuity comes attached at the hip to change of the self over time. Life is change, and we celebrate it. But we lose so very much in the course of that change that it seems matters really could be better managed. The figure for 98% loss of memory over weeks arises from self-experiments carried out by a determined fellow in the late 1800s, and which have been repeated every so often by the research community ever since. A replication paper was published just last year, for example. This enormous loss is the way things work for normal humans, and coupled with the adrenaline mechanism for selective additional memory of events that matter, one can see how this sort of a system might have evolved. A prehistoric lifespan is the same few tasks with very minor variations repeated over and again until death or disability, interspersed with a much smaller number of painful and terrifying learning experiences, with each new generation running the same rat wheel as the previous.
There are claims of people with extraordinary memory, or even eidetic or photographic memory, but the scientific community is far from settled on the question of the degree to which these claims result from (a) misinterpreting the top end of the curve for normal variation in memory capacity, versus (b) narrowly specialized memory training, versus (c) some form of genuinely unusual and exceptional ability based on neurobiological differences yet to be described. The mechanisms of memory are being deciphered in the laboratory, however, and there are various demonstrations of a modest degree of enhanced memory in animal studies. The question of whether greatly enhanced memory can be induced through near future medicine remains open: it will certainly happen eventually, but when will it start in earnest, and when will it go beyond adding only few more percentage points to the fraction of events we recall from our lives? It seems to me that this is a goal that should be given a far greater priority than is the case today. Consider that if we had perfect memory, what would we think of someone who forget near everything he or she did? We would call it a medical condition and offer support, in the same way that the medical community seeks to treat and aid people suffering age-related cognitive decline or amnesia today. If there were a great many of those people, there would be an enormous investment in the search for a cure, just as we do today for Alzheimer's disease. But because our disability is normal and shared, there is no such effort.
Latest Headlines from Fight Aging!
Hunter-Gatherer Data Used to Evaluate the Effects of Exercise on Long-Term Health
To what degree does regular exercise beyond the recommended minimum of 30 minutes a day improve long-term health and life expectancy? This and related questions on the shape of the dose-response curve for aerobic exercise remain open for debate. It is clear that being sedentary has a cost in terms of health and life expectancy, and the balance of evidence to date suggests that the 80/20 point for benefits due to exercise is found somewhere higher than the generally recommended level. Yet it is unclear as to whether professional athletes, who tend to live longer than the general population, live longer because of the high levels of exercise or because they also tend to be more robust individuals who would have enjoyed greater longevity regardless of profession. While it remains to put good numbers to much of the dose-response curve for exercise, this study of the Hadza people adds to the evidence for additional benefits to accrue to those who go beyond 30 minutes a day:
The Hadza live a very different kind of lifestyle - and a very active one, engaging in significantly more physical activity than what is recommended by U.S. government standards. They also have extremely low risk of cardiovascular disease. Researchers have spent several years studying the lifestyle of the Hadza. "Our overall research program is trying to understand why physical activity and exercise improve health today, and one arm of that research program aims to reconstruct what physical activity patterns were like during the evolution of our physiology. The overarching hypothesis is that our bodies evolved within a highly active context, and that explains why physical activity seems to improve physiological health today."
The U.S. Department of Health and Human Services recommends that people engage in 150 minutes per week of moderate intensity activity - about 30 minutes a day, five times a week - or about 75 minutes per week of vigorous intensity activity, or an equivalent combination of the two. However, few Americans achieve those levels. The Hadza, on the other hand, meet those weekly recommendations in a mere two days, engaging in about 75 minutes per day of moderate-to-vigorous physical activity, or MVPA. Furthermore, and consistent with the literature identifying aerobic activity as a key element necessary to a healthy lifestyle, researchers' health screenings of Hadza people have shown that the population has extremely low risk for heart disease. "They have very low levels of hypertension. In the U.S., the majority of our population over the age of 60 has hypertension. In the Hadza, it's 20 to 25 percent, and in terms of blood lipid levels, there's virtually no evidence that the Hadza people have any kind of blood lipid levels that would put them at risk for cardiovascular disease."
While physical activity may not be entirely responsible for the low risk levels - diet and other factors may also play a role - exercise does seem to be important, which is significant because humans' physical activity levels have drastically declined as we have transitioned from hunting and gathering to farming to the Industrial Revolution to where we are today. "Over the last couple of centuries, we've become more and more sedentary, and the big shift seems to have occurred in the middle of the last century, when people's work lives became more sedentary. In the U.S., we tend to see big drop-offs in physical activity levels when people age. In the Hadza, we don't see that. We see pretty static physical activity levels with age. This gives us a window into what physical activity levels were we like for quite a while during our evolutionary history, and, not surprisingly, it's more than we do now. Perhaps surprisingly, it's a whole lot more than we do now. Going forward, this helps us model the types of physical activity we want to be looking at when we explore our physiological evolution. When we ask what kinds of physical activity levels would have driven the evolution of our cardiovascular system and the evolution of our neurobiology and our musculoskeletal system, the answer is not likely 30 minutes a day of walking on a treadmill. It's more like 75-plus minutes a day."
Comparing Gene Expression Profiles of Mammalian Species in Order to Search for the Determinants of Longevity
The comparative biology of aging and longevity, comparing the biochemistry of similar species with different life spans, is a good way to improve understanding of which aspects of our biology are important determinants of degeneration and age-related disease. In the open access paper linked here, researchers undertake an examination of gene expression profiles in cell cultures for a range of mammalian species, for example. Despite the usefulness, as an investigative method this will, I expect, be overtaken by prototype rejuvenation therapies based on damage repair in the years ahead. Aging is an accumulation of cell and tissue damage, and the best way to determine the contribution of any one particular type of damage is to remove it. Researchers are beginning that process for cellular senescence, now that senescent cells can be selectively destroyed in an efficient manner, and other items from the SENS portfolio of rejuvenation biotechnologies will be added as they reach the stage of practical demonstration in animal studies.
The maximum lifespan of mammalian species differs by more than 100-fold, ranging from ~2 years in shrews to more than 200 years in bowhead whales. While it has long been observed that maximum lifespan tends to correlate positively with body mass and time to maturity, but negatively with growth rate, mass-specific metabolic rate, and number of offspring, the underlying molecular basis is only starting to be understood. One way to study the control of longevity is to identify the genes, pathways, and interventions capable of extending lifespan or delaying aging phenotypes in experimental animals. Studies using model organisms have uncovered several important conditions, such as knockout of insulin-like growth factor 1 (IGF-1) receptor, inhibition of mechanistic target of rapamycin (mTOR), mutation in growth hormone (GH) receptor, ablation of anterior pituitary (e.g. Snell dwarf mice), augmentation of proteins of the sirtuin family, and restriction of dietary intake. While many of these genes and pathways have been verified in yeast, flies, worms, and mice, the comparisons largely involve treatment and control groups of the same species, and the extent to which they explain the longevity variations across different species is unclear. For example, do the long-lived species have metabolic profiles resembling calorie restriction? Do they suppress IGF-1 or growth hormone signaling compared with the shorter-lived species? More generally, how do the evolutionary strategies of longevity relate to the experimental strategies that extend lifespan in model organisms?
To address these questions, a popular approach has been to compare exceptionally long-lived species with closely related species of common lifespan and identify the features associated with exceptional longevity. Examples include the amino acid changes in Uncoupling Protein 1 (UCP1) and production of high-molecular-mass hyaluronan in the naked mole rat; unique sequence changes in IGF1 and GH receptors in Brandt's bat; gene gain and loss associated with DNA repair, cell-cycle regulation, and cancer, as well as alteration in insulin signaling in the bowhead whale; and duplication of the p53 gene in elephants. Again, it is important to ascertain whether these mechanisms are unique characteristics of specific exceptionally long-lived species, or whether they can also help account for the general lifespan variation.
An extension of this approach has been cross-species analyses in a larger scale. For example, several biochemical studies across multiple mammalian and bird species identified some features correlating with species lifespan. Longevity of fibroblasts and erythrocytes in vitro, poly (ADP-ribose) polymerase activity, and rate of DNA repair were found to be positively correlated with longevity, whereas mitochondrial membrane and liver fatty acid peroxidizability index, rate of telomere shortening, and oxidative damage to DNA and mitochondrial DNA showed negative correlation. The advent of high throughput RNA sequencing (RNAseq) and mass spectrometry technologies has enabled the quantification of whole transcriptomes, metabolomes, and ionomes, across multiple species and organs. These studies revealed the complex transcriptomic and metabolic landscape across different organs and species, as well as some overlaps with the changes observed in the long-lived mutants created in laboratory.
While molecular profiling of mammals at the level of tissues may better represent the underlying biology, profiling in cell culture represents more defined experimental conditions and allows further manipulation to alter the identified molecular phenotypes. In this study, we examined the transcriptomes and metabolomes of primary skin fibroblasts across 16 species of mammals, to identify the molecular patterns associated with species longevity. We report that the genes involved in DNA repair and glucose metabolism were up-regulated in the longer-lived species, whereas proteolysis and protein translocation activities were suppressed. The longer-lived species also had lower levels of lysophosphatidylcholine and lysophosphatidylethanolamine and higher levels of amino acids; and the latter finding was validated in an independent dataset of bird and primate fibroblasts.
Interleukin-1 Receptor Antagonists as a Stroke Treatment
Researchers here investigate a class of drug that blocks interleukin-1 receptor activity, something that has been found to reduce cell death and improve regeneration following stroke. This form of interference in cellular metabolism lowers the level of inflammation, but that may or may not be the most important mechanism in the outcome for stroke patients; it is plausible, but the details remain to be determined conclusively at this point.
The pro-inflammatory cytokine interleukin-1 (IL-1) is a major driver of inflammation, with well documented detrimental effects in multiple preclinical models of systemic inflammatory disease as well as in cerebral ischemia. To this end, the selective, naturally occurring competitive inhibitor of IL-1, interleukin-1 receptor antagonist (IL-1Ra) has shown potential as a new treatment for stroke. More specifically, in a number of experimental stroke paradigms IL-1Ra reduces infarct volume and improves long term functional outcome, including in co-morbid animals. However, exact mechanisms by which IL-1Ra is neuroprotective are yet to be fully established.
While much research has focused on limiting ischemic damage in the initial stages of acute reperfusion, it is also important to understand mechanisms that underpin brain repair following injury and develop strategies that enhance reparative endogenous processes, including adult neurogenesis. Ischemic injury elicits a robust neurogenic response by stimulating production of neuronal progenitor cells (NPCs) in distinct neurogenic regions, which include the subventricular zone (SVZ) and the subgranular zone (SGZ), to generate new functional neurons. Though mechanisms underlying post-stroke neurogenesis and the influence of inflammation on these processes are still poorly understood, it has been observed in young and aged animals that inflammation impairs both basal levels of neurogenesis and attenuates the neurogenic response triggered by central nervous system (CNS) injury via induction of the pro-inflammatory cytokines. IL-1, for example, reduces the proliferation and differentiation of NPCs to neurons in pathologies such as stress and depression, effects reversed by administration of IL-1Ra.
Here, we explored how inhibition of IL-1 actions by clinically relevant, delayed administration of subcutaneous IL-1Ra affects stroke outcome and neurogenesis up to 28 days after experimental ischemia, in aged/co-morbid and young rats. All experiments were performed using 13-month-old male, lean and corpulent (Cp) rats and 2-month-old Wistar rats. Cp rats are homozygous for the autosomal recessive cp gene (cp/cp), and spontaneously develop obesity, hyperlipidemia, insulin resistance, glomerular sclerosis, and atherosclerosis. Delayed IL-1Ra administration at 3 and 6 hours reperfusion in aged lean, aged Cp and young Wistar rats induced a significant reduction in infarct volume at 24 hours and 7 days of reperfusion, and a significant reduction in cortex loss at 28d in young Wistar rats. Reductions in infarct volume at 24 hours of reperfusion were 37%, 42% and 40% in aged lean, aged Cp and young Wistar rats respectively. IgG staining at 7 days reperfusion revealed a reduction of 40%, 48% and 46% in blood-brain barrier (BBB) damage in IL-1Ra treated aged lean, aged Cp and young Wistar animals respectively, versus their placebo-treated counterparts. A reduction of 26% was also observed at 14d reperfusion in young Wistar rats treated with IL-1Ra versus their placebo counterparts.
Our findings demonstrate that subcutaneous administration of IL-1Ra is neuroprotective in young and aged animals with multiple risk factors for stroke and increases post-stroke neurogenesis. It has previously been observed that delayed administration of IL-1Ra exerts neuroprotective effects at acute time points following experimental ischemia. Here we extend these findings to show that the early beneficial effects of IL-1Ra persist for at least 7 days in aged/co-morbid animals and for 28 days in young/healthy animals. Our data show that although 13-month-old corpulent rats had a plethora of stroke associated co-morbidities, infarct volumes were of a similar size to aged leans, suggesting that the extent of ischemic damage was close to maximal and that no further increase was possible. Conversely, younger rats were more resistant. This suggests that age is the primary variable that increases the brain susceptibility to infarction following an ischemic stroke. However, despite reaching maximal levels of infarction, tissue is still salvageable under these circumstances if IL-1Ra is administered within a therapeutic window.
Furthermore, our results indicate that although the delayed administration of IL-1Ra (3 and 6 hours from reperfusion onset) reduces infarct volume, it produces an increase on cellular proliferation and migration of immature neurons versus placebo counterparts in the SVZ following stroke in young and aged/co-morbid rats, suggesting that a reduced inflammation of the tissue fosters a more efficient repair of the damaged tissue. We also show that IL-1Ra increases the number of new integrated neurons in areas surrounding the infarct lesion in young animals compared to placebo groups a result that correlates with improvements in motor and behavioral sub-acute outcomes. The benefits of IL-1Ra are therefore not limited to inducing neuroprotection, but also favor and promote neurorepair mechanisms. We conclude that further studies are required to fully elucidate the mechanisms through which IL-1Ra may be mediating its beneficial, neurogenic effects.
Incidence of High Blood Pressure Rises and Spreads, Following Increased Wealth
Rates of obesity and high blood pressure, or hypertension, follow the increases in wealth and comfort that have spread through much of the world over the past 60 years. Regions that are in the process of transitioning from predominantly poor agricultural populations to a level of wealth and mix of occupations that looks much more like Europe or the US, with South Korea as a good example of the full span of such a transition, see rising life expectancy as well as a rising level of lifestyle conditions. High blood pressure drives the development of cardiovascular disease, and is made worse by excess fat tissue and lack of exercise. Though at present we can't do much about the root cause of age-related increases in blood pressure, which is loss of elasticity in blood vessels, other than fund the most promising research that offers a path to meaningful therapies, we can adopt lifestyle choices that avoid making the problem larger than it has to be. Further, the past 20 years have seen some surprisingly effective advances in controlling high blood pressure through medication, surprising since these results have been achieved without doing much to address the underlying causes, but the very widespread use of these therapies has yet to spread to some of the regions that are now seeing increased incidence of hypertension.
In the past 40 years, there has been a large increase in the number of people living with high blood pressure worldwide because of population growth and ageing - rising from 594 million in 1975 to over 1.1 billion in 2015. The largest rise in the prevalence of adults with high blood pressure has been in low- and middle-income countries (LMICs) in south Asia (eg, Bangladesh and Nepal) and sub-Saharan Africa (eg, Ethiopia and Malawi). But high-income countries (eg, Australia, Canada, Germany, Sweden, and Japan) have made impressive reductions in the prevalence of adults with high blood pressure, according to the most comprehensive analysis of worldwide trends in blood pressure to date.
Both elevated systolic (higher than 140 mmHg; first number in blood pressure reading) and diastolic (higher than 90mmHg) blood pressure can be used to make a diagnosis of high blood pressure. Recent research suggests that the risk of death from ischemic heart disease and stroke doubles with every 20 mmHg systolic or 10 mmHg diastolic increase in middle and older ages. Over the past four decades, the highest average blood pressure levels have shifted from high-income western countries (eg, Norway, Germany, Belgium, France) and Asia-Pacific countries (eg, Japan) to LMICs in sub-Saharan Africa, South Asia, and some Pacific island countries. High blood pressure remains a serious health problem in central and eastern Europe (eg, Slovenia, Lithuania). The findings come from a comprehensive new analysis of global, regional, and national trends in adult (aged 18 and older) blood pressure between 1975 and 2015. This includes trends in average systolic (the maximum pressure the heart exerts while beating) and diastolic blood pressure (amount of pressure in the arteries between beats), as well as prevalence of high blood pressure. The Non-Communicable Disease (NCD) Risk Factor Collaboration pooled data from 1479 population-based studies totalling 19.1 million men and women aged 18 years or older from 200 countries (covering more than 97% of the world's adult population in 2015).
"High blood pressure is the leading risk factor for stroke and heart disease, and kills around 7.5 million people worldwide every year. Most of these deaths are experienced in the developing world. Taken globally, high blood pressure is no longer a problem of the Western world or wealthy countries. It is a problem of the world's poorest countries and people. Our results show that substantial reductions in blood pressure and prevalence are possible, as seen in high-income countries over the past 40 years. They also reveal that WHO's target of reducing the prevalence of high blood pressure by 25% by 2025 is unlikely to be achieved without effective policies that allow the poorest countries and people to have healthier diets - particularly reducing salt intake and making fruit and vegetables affordable - as well as improving detection and treatment with blood pressure lowering drugs."
Data on the Effects of Follistatin Gene Therapy from BioViva
Back in 2015, Elizabeth Parrish underwent telomerase and follistatin gene therapy as a part of forming the startup BioViva: a human safety trial of one person, made public as a way to push the bounds of the current debate over when we should get started on human testing of these technologies. Personally, I agree that there is too much talk, too much unnecessary caution and hand-wringing, and not enough action. Sooner rather than later is better, especially given the large amount of animal data showing safety. Parrish is to be congratulated for forging ahead.
The latter of these two gene therapies is more interesting to me, as there is much more evidence in animal studies of the safety and effectiveness of either directly suppressing myostatin or enhancing follistatin to suppress myostatin. This has the effect of increasing muscle mass and reducing fat tissue, along the way tuning the operation of metabolism into a healthier mode of operation. It seems to me to be an enhancement that everyone should undergo, based on the evidence to date: a way to improve health and slow the age-related loss of muscle mass and strength. BioViva has now released some more data on the long term effects of the gene therapies, which show increased muscle mass, reduced fat, and improved aspects of metabolism. In a study of one, this should be taken as an anecdote, especially given that these items can all be changed over the longer term to some degree by lifestyle adjustments. The important thing is that safety has been proven, and that there appear to be benefits is just an added incentive to move to the next step of larger studies and availability of therapy via medical tourism. Hopefully the company will find the funding to achieve both of these goals.
In April 2016 BioViva stated that Elizabeth Parrish, CEO, had experienced telomere lengthening in her leukocytes, as a result of an injection of two experimental therapies. These consisted of a myostatin inhibitor to protect against loss of muscle mass with age, and a telomerase inducer to battle stem cell depletion responsible for diverse age-related diseases and infirmities. While the test was designed to establish the first human safety data regarding telomerase induction, in tests conducted by SpectraCell Laboratories, data indicated that her leukocyte telomeres had lengthened by approximately 20 years, from 6.71kb to 7.33kb. Further data will be released later this year. Upon further examination and testing, comparison of Parrish's data prior to the therapy and following the therapy has revealed additional positive changes. MRI scans taken before and after depict a slight increase in muscle size in conjunction with a noticeable reduction in muscle fat content. An over-accumulation of intramuscular fat, also known as 'marbling', is associated with increased insulin resistance, and as such an appropriate reduction may be linked to beneficial metabolic changes, in addition to the improved musculature. The aforementioned patient's total body weight has also not decreased during this period, and as such weight loss is not a confounding variable. The muscle growth achieved post-therapy corresponds with observed improvements in patients with Becker's Muscular Dystrophy, after receipt of myostatin inhibition gene therapy.
Researchers have noted that a significant reduction in fasting glucose was apparent in mice following telomerase gene therapy. The subject's fasting glucose has declined from previous measurements of 94 mg/dL and 86 mg/dL, to a fasting glucose level of 71 mg/dL by August 2016, as measured by Quest Diagnostics. Repeated testing will confirm the implied increase in insulin sensitivity. Previous research has also indicated that telomerase deficiency impairs glucose metabolism and insulin secretion in telomerase deficient mice, which may explain an apparent improvement in metabolic markers. In accordance with an improvement in metabolic health, triglyceride levels have also declined from 140 mg/dL in 2015 prior to the therapy, to 36 mg/dL in February 2016, subsequently rising to 80 and 84 mg/dL in August 2016. While there has been an increase in blood triglyceride content following the February reading, it is still measurably lower than before treatment. Both decreases in fasting glucose and triglycerides can be potentially explained by prior studies, of both telomerase and myostatin. Raised myostatin mRNA seen in type 2 diabetes patients is associated with impaired insulin sensitivity, raising triglyceride levels and low-grade chronic inflammation. Myostatin inhibition in mice has also been shown to reduce triglyceride levels and improve insulin sensitivity.
No negative effects have been reported, and there are no visible detrimental effects in blood analysis thus far; providing tentative evidence of safety in the first human test of BioViva's dual gene therapy strategy.
Sarcopenia Finally Obtains an ICD Code
A recent commentary celebrates the granting of an International Classification of Disease (ICD) code to sarcopenia, an important step in the lengthy formal definition of a disease. Sarcopenia is the characteristic age-related decline of muscle mass and strength - though many would say that it only counts as sarcopenia if that decline is significantly greater than normal, and that "normal aging" should not be treated. Hopefully those voices will decline in the years ahead. The carving up of degenerative aging into named conditions is a long, slow, and messy process. It is driven by regulation rather than any sort of common sense goal, as regulators refuse to approve treatments for aspects of aging that are not formally defined as a disease. Thus there is far less funding and interest in those fields, and consequently slow progress. Turning reality into a regulatory definition requires lobbying, extensive debate, and a great deal of money that would be better spent on other things. In the case of sarcopenia, it has taken more than decade of work to get to the point at which the formal definitions of disease start to crystallize into bureaucratic acceptance. So much wasted time.
Sarcopenia has come a long way since Irwin Rosenberg first suggested the term to apply to age-related muscle mass. In 2010, the European Working Group on Sarcopenia defined sarcopenia as low muscle mass together with low muscle function (strength or performance). Subsequently, other international groups developed similar definitions for sarcopenia focusing on walking speed or distance walked in 6 min or grip strength in persons with lean muscle mass. A number of studies have confirmed the validity of these definitions. Based on the available literature, it would appear that sarcopenia is present in 5 to 10% of persons 65 years of age or older. This high quality research approach to sarcopenia has led to the recognition of sarcopenia as a disease entity with the awarding of an ICD-10-CM (M62.84) code in September, 2016. This is an important step similar to the much earlier recognition of osteoporosis as a disease state. This will lead to an accelerated interest in physicians making the diagnosis of sarcopenia and for pharmaceutical companies to accelerate the interest in developing drugs to treat sarcopenia. This research will be helped by there already being a number of biomarkers available for sarcopenia. This should also drive an increase in diagnostic tool availability for recognizing sarcopenia.
Sarcopenia is the most important cause of frailty in older persons. In addition, there is a close association between sarcopenia and bone loss and hip fracture - osteosarcopenia. Sarcopenia has also been found to be a major reason for poor outcomes in persons with diabetes mellitus. SARC-F is a simple screening test for sarcopenia. It prospectively identifies decreased walking speed, activities of daily living disability, hospitalization, and mortality. It has been shown to correlate well with the available international definitions for sarcopenia. There are numerous causes of sarcopenia including anorexia, inflammation, hypogonadism, lack of activity, hypovitaminosis D, motoneuron loss, insulin resistance, poor blood flow to muscle, mitochondrial dysfunction, and genetic causes. The established treatment for sarcopenia is resistance exercise. It appears that sarcopenia is always responsive to resistance exercise. Supplementation with leucine enriched, essential amino acid can also enhance muscle rejuvenation. Vitamin D declines with ageing, and supplementation enhances muscle function when deficient. Testosterone is the drug with the strongest record for increasing muscle mass and improving function. Anamorelin improves muscle mass but not strength. A number of other drugs are under development focusing mainly on myostatin and activin-2 receptor inhibitors. Selective androgen receptor molecules (SARMs) have also shown positive effects. Overall, the availability of an ICD-10 code for those of us who work in the area of muscle wasting disease is a very exciting time. Over the next few years, we can expect major advances in the treatment of older persons with sarcopenia.
Stem Cell Research and the Treatment of Neurodegenerative Diseases
In this open access review paper, the authors make a case for more human trials in the development of stem cell therapies to treat neurodegenerative diseases. An abundance of caution and heavy regulatory burden drives greater use of animal studies than is perhaps merited given the safety data derived from the first of those studies, which in turn leads to high cost and a high rate of failure in development. A more rapid move to human trials after proving safety in animals is one possible solution to this problem. Another is for large improvements in the quality and cost of on-demand growth of small brain tissue sections that exhibit specific disease characteristics, but even then it is still important to transition to human trials sooner after safety is proven rather than later.
Progress in the field of clinical research and medicine has decreased global mortality drastically. The developed countries have extended the life span of their aging population. However, the modern world is now faced with the issues of aging and age related disorders. Neurodegeneration and neurodegenerative disorders are one of the major health implications faced by the aging population. Neurodegenerative disorders have been thoroughly investigated using animal models, primary cultures, and post mortem human brain tissues. Though informative, these approaches have some limitations. Data obtained from animal models fails to directly correlate with that of humans because a rodent brain is not an exact mimic of a human brain. Despite being highly conserved evolutionarily, mammalian genomes are not identical. Therefore species difference prevents the animal data from successful validation during clinical field trials which poses a severe economic burden. Preclinical studies often do not efficiently translate to the clinic and the clinical trial failures have been reported time and again. Primary culture of neurons is challenging because these are the post mitotic differentiated cells which are difficult to sustain in the in-vitro conditions. Ethical constraints have held back human based research and thus the best possible source of human samples are the postmortem brain tissues. However, these autopsied samples depict the end stages of the disease and do not give much insight into the intricacies of the disease' developing stages. Researchers are not willing to subject the human beings to untested interventions, but the choices have been limited so far.
Majority of neurodegenerative disorders have been incurable (Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis) so far but timely diagnosis can help in the management and symptom alleviation. However, researchers across the world are continuously striving to achieve the cure and hope to achieve fruitful results in the near future. Neurodegeneration studies are largely divided into two major categories. One is the experimental modeling strategy which allows for a comprehensive understanding of the disease such as the etiology, pathophysiology, genotypic-phenotypic interactions, symptomatic, and mechanistic insights. The second is the medical approach which deals with the treatment, therapy, and disease management. Stem cells and iPSCs find widespread application for both, disease modeling as well as transplantation and regenerative therapeutics. In the present review we shall discuss the applicability of stem cell research in the field of neurodegenerative disease modeling and provide the current updates of how stem cell and induced pluripotent stem cell based studies have been employed to address the diagnosis and therapy of the most common neurodegenerative disorders. We shall briefly touch upon the advances and preferable methodologies employing stem cell and iPSC culture such as the three dimensional (3D) culture which has revolutionized the current trend of in-vitro studies. The article intends to highlight the fact, that though animal based in-vivo research is absolutely necessary for the neuroscience research, one cannot wholly and solely depend upon it and human based stem cell driven research has and will open newer avenues for the neurodegenerative disorders′ modeling and treatment.
Another Group Argues for Alzheimer's Disease to be a Diabetic Condition
A number of the aspects of Alzheimer's disease biochemistry have a strong similarity to aspects of type 2 diabetes biochemistry. Alzheimer's also has the same risk factors, such as the presence of excess visceral fat tissue. Some researchers have gone so far as to call for the classification of Alzheimer's as type 3 diabetes. While not official, there has been enough of this sort of discussion over the years that when type 4 diabetes was discovered it had to be called type 4 in order to avoid the inevitable confusion. It is very unclear as to where the diabetic aspects of Alzheimer's disease fit in the long chain of cause and effect that leads from fundamental damage that causes aging to age-related disease, and so equally unclear as to how effective it can be in the best case to undertake efforts to adjust this biochemistry. Nonetheless, the research linked here is one of many examples in which Alzheimer's has facets that strongly resemble diabetes:
Researchers have found a promising treatment for Alzheimer's disease, by noticing a similarity in the way insulin signaling works in the brain and in the pancreas of diabetic patients. In the pancreas, the Kir6.2 channel blockade increases the insulin signaling, and insulin signaling decreases the blood glucose levels. In the brain, insulin signaling increases the acquisition of memory through CaM kinase II activation by Kir6.2 channel blockade. The research group thus concluded that Alzheimer's disease can be described as a diabetic disorder of the brain. Memantine, a drug widely used to treat Alzheimer's disease, is a well known inhibitor of the N-methyl-D-aspartate (NMDA) receptors that prevent excessive glutamate transmission in the brain. Researchers have now found that memantine also inhibits the ATP-sensitive potassium channel (Kir6.2 channel), improving insulin signal dysfunction in the brain.
In their experiment with mice, the researchers found that memantine treatment improved impaired hippocampal long-term potentiation (LTP) and memory-related behaviors in the mice through the inhibition of KATP channel Kir6.2. "Our results suggest that Kir6.2 blockade in dendritic spines by memantine regulates CaMKII activity by increasing intracellular Ca2+ mobilization, which in turn improves cognitive function by promoting AMPAR trafficking into the postsynaptic membrane. Since KATP channels Kir6.1 or Kir6.2 are critical components of sulfonylurea receptors (SURs) which is downstream insulin receptor signaling, the KATP channel inhibition by Memantine mediates the anti-diabetic drug action in peripheral tissues. And this leads to improved cognitive functions and improved memory retention among Alzheimer's patients." The researchers now hope that results of their study and the parallels drawn with diabetes, will lead to new treatments for Alzheimer's disease, using the inhibition of Kir6.2 channel.
A Reasonable Perspective on Cryonics
In this article, one of the scientists involved in our rejuvenation research community outlines a very reasonable view on cryonics and cryopreservation. Cryonics is the low-temperature preservation of at least the brain following death, done these days with the use of cryoprotectants and vitrifiction to minimize ice crystal formation. It offers an unknown chance at a future restoration to life: technology marches onwards year after year, and for so long as the structures that encode the data of the mind are preserved, there is the possibility of living again in a future age that has mastered the technologies needed for restoration. This would include, at a minimum, comprehensive control over cellular biology and some form of advanced molecular nanotechnology. Even in our present era, there is considerable interest in developing reversible vitrification for organ storage, to ease the logistics of tissue engineering and organ donation and transplantation, and early proof of concept experiments have taken place in that field. The types of technology that would be needed to restore a preserved cryonics patient can be envisaged by extrapolation from present efforts in that field and in the work being carried out on rejuvenation therapies.
A teenager who tragically died of cancer recently has become the latest among a tiny but growing number of people to be cryogenically frozen after death. These individuals were hoping that advances in science will one day allow them to be woken up and cured of the conditions that killed them. But how likely is it that such a day will ever come? Nature has shown us that it is possible to cryopreserve animals like reptiles, amphibians, worms and insects. Nematode worms trained to recognise certain smells retain this memory after being frozen. The wood frog (Rana sylvatica) freezes during winter into a block of ice and hops around the following spring. However, in human tissue each freeze-thaw process causes significant damage. Understanding and minimising this damage is one of the aims of cryobiology.
At the cellular level, these damages are still poorly understood, but can be controlled. Each innovation in the field relies on two aspects: improving preservation during freezing and advancing recovery after thawing. During freezing, damage can be avoided by carefully modulating temperatures and by relying on various types of cryoprotectants. One of the main objectives is to inhibit ice formation which can destroy cells and tissues by displacing and rupturing them. For that reason, a smooth transition to a "glassy stage" (vitrification) by rapid cooling, rather than "freezing", is the aim. Reviving whole bodies also poses its own challenges as organs need to commence function homogeneously. The challenges of restoring the flow of blood to organs and tissues are already well-known in emergency medicine. But it is perhaps encouraging that cooling itself does not only have negative effects - it can actually mitigate trauma. In fact, drowning victims who have been revived seem to have been protected by the cold water - something that has led to longstanding research into using low-temperature approaches during surgery.
The pacemakers of scientific innovation in cryobiology are both medical and economic. Many advances in cell preservation are driven by the infertility sector and an emerging regenerative medicine sector. Cryopreserved and vitrified cells and simple tissues (eggs, sperm, bone marrow, stem cells, cornea, skin) are already regularly thawed and transplanted. Work has also started on cryopreservation of "simple" body parts such as fingers and legs. Some complex organs (kidney, liver, intestines) have been cryopreserved, thawed, and successfully re-transplanted into an animal. While transplantation of human organs currently relies on chilled, not frozen, organs, there is a strengthening case for developing cryopreservation of whole organs for therapeutic purposes.
But there's another huge hurdle for cryonics: to not only repair the damage incurred due to the freezing process but also to reverse the damage that led to death - and in such a manner that the individual resumes conscious existence. So will it one day be possible to cryopreserve a human brain in such a manner that it can be revived intact? Success will depend on the quality of the cryopreservation as well as the quality of the revival technology. Where the former is flawed, as it would be with current technologies, the demands on the latter increase. This has led to the suggestion that effective repair must inevitably rely on highly advanced nanotechnology - a field once considered science fiction. The idea is that tiny, artificial molecular machines could one day repair all sorts of damage to our cells and tissues caused by cryonics extremely quickly, making revival possible. Given the rapid advances in this field, it may seem hasty to dismiss the entire scientific aim behind cryonics.
Embryonic Gene Hoxa9 Reactivates with Age to Limit Muscle Stem Cells
The changes that take place in stem cell populations with age are most studied in muscle tissue at the present time. Stem cells in old tissue spend ever more time quiescent rather than active, and thus the supply of new somatic cells needed to maintain and repair muscle declines. From the evidence accumulated to date this appears to be largely driven by changes in signaling rather than molecular damage to the stem cells themselves, though there is that as well. Researchers are attempting to catalog these signals with the hope of overriding them in order to restore youthful levels of regeneration in aged patients, and the research noted here is one example of this type of research. The decline in stem cell activity with age is thought to be part of an evolved balance between death by lack of tissue maintenance on the one hand and death by cancer on the other. Lower rates of stem cell activity reduces the chance of a damaged cell running amok. However, the use of stem cell therapies that change signals to put native cells back to work, and studies of telomerase gene therapy that has much the same effect, so far suggest that there is a fair amount of room to improve the situation without significantly raising the risk of cancer.
The development of the embryo during pregnancy is one of the most complex processes in life. Genes are strongly activated, and developmental pathways must do their job in a highly accurate and precisely timed manner. So-called Hox-genes play an important regulatory role in this process. Although remaining detectable in stem cells of adult tissues throughout life, after birth they are only rarely active. Now, however, researchers have shown that, in old age, one of these Hox-genes (Hoxa9) is strongly re-activated in murine muscle stem cells after injury; leading to a decline in the regenerative capacity of skeletal muscle. Interestingly, when this faulty gene re-activation was inhibited by chemical compounds, muscle regeneration was improved in aging mice, thus suggesting novel therapeutic approaches aimed at improving muscle regeneration in old age.
The biggest surprise from the current study is that the re-activation of Hoxa9 after muscle injury in old age impairs the functionality of muscle stem cells instead of improving it. Originally, Hoxa9-induced developmental pathways are responsible for the proper development of body axes - for example, during development of the fingers of a hand. A decline in stem cell functionality leads to an unavoidable decrease in the regenerative capacity of the whole skeletal muscle. With age, this may weaken the muscular strength after injury. The courses of stem cell and tissue aging are yet to be completely understood. It has already been recognized that signals which control the development of the embryo become activated in aging stem cells. However, the regulator-genes controlling these signals have not yet been analyzed in aging. "From an evolutionary perspective, Hox-genes are very old. They regulate organ development across almost the entire animal kingdom - from flies up to humans. It is a huge surprise that the faulty re-activation of these genes leads to stem cell aging in muscle. This finding will fundamentally influence our understanding of the courses of aging. Surprisingly, old muscle stem cells did not show a faulty activation of the epigenome in quiescence - the resting stage in non-injured muscle. Only in response to a muscle injury, do the stem cells display an abnormal epigenetic stress response, which leads to the opening of DNA and, thus, to the activation of developmental pathways."
The researchers now plan to investigate whether a similar re-activation of embryonic genes is also causative for the loss of muscle maintenance in aging humans. Medical compounds that limit alterations in the epigenome may improve the regenerative capacity of muscles in old mice. Thus far, this approach is too unspecific and affects the modification of genes in several cells and tissues. For this reason, a collaborative study is primed to investigate whether a nanoparticle-induced, target-specific inhibition of Hox-genes in muscle stem cells is feasible and, if so, would it be sufficient to improve muscle regeneration and maintenance.