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- Cellular Senescence as a Contributing Cause of Osteoarthritis
- Extending Yeast Lifespan with Lithocholic Acid
- Rejuvenation Biotechnology Update for January 2017
- Building a Better Cellular Senescence Assay: LongeCity Puts Forward a 3000 Matching Challenge for the CellAge Fundraiser
- Biologically Modified Justice
- Latest Headlines from Fight Aging!
- International Longevity and Cryopreservation Summit in Spain, May 2017
- Human Longevity Variations are Largely Due to Unknown Genetic and Environment Differences or Simple Chance?
- Targeting PAD4 Reduces Age-Related Fibrosis
- A Role for Pericyte Dysfunction in Neurodegenerative Conditions
- Glucose Deprivation in Alzheimer's Disease Progression
- In Search of Lipid Signatures of Longevity in Mammalian Species
- More Results for the Use of Immune System Reconstruction to Treat Autoimmunity
- Investigating the Details of Slowed Immune Aging via Calorie Restriction
- An Interview with Irina and Michael Conboy on Blood Factors in Aging
- Short Term Damage Done by Amyloid in the Brain Appears to be Reversible
Cellular Senescence as a Contributing Cause of Osteoarthritis
A fair few good scientific papers on the role of cellular senescence in the progression of osteoarthritis have emerged in the last year. Given that UNITY Biotechnology aims to initially trial senolytic therapies to clear senescent cells as a treatment for inflammatory joint diseases, a list in which osteoarthritis features prominently, and that the UNITY principals now have quite a lot of funding to work with, I expect that we'll be hearing a lot more on this topic over the course of the next few years. There is nothing quite like the existence of a funded company in a field to spur a great deal more investment in related research from all sources. The rate at which reviews of the relevant science are published tends to increase as well, with the paper linked below as an example of the type.
Senescent cells accumulate in tissues with age, and that accumulation is thought to be one of the causes of degenerative aging. While the immune system tends to destroy most of the senescence cells that fail to destroy themselves, its declining effectiveness in later life helps to ensure that the count of senescent cells keeps rising. In small numbers these cells are harmless; they have a role in wound healing, senescence followed by destruction is the normal end state for all somatic cells that reach the Hayflick limit, and senescence in response to damage or toxic stress helps to prevent cancer by removing those cells most at risk. Senescent cells secrete a potent mix of signal molecules, however, and when present in larger numbers this senescence-associated secretory phenotype (SASP) produces considerable harm. In the case of conditions driven by inflammation, or with strong inflammatory components, such as osteoarthritis, perhaps the most relevant aspect of cellular senescence is that the SASP includes pro-inflammatory signals. Senescent cells generate greater local inflammation, and more of all the consequences that follow on from that.
That rising inflammation has such an important role in the progression of many age-related conditions, and that senescent cells are a notable source of inflammation, are reasons to think that targeted removal of senescent cells should be broadly beneficial for human patients. The sooner that senolytic therapies can be brought to the clinic, the better. Currently the near term prospects seem quite hopeful, since the initial brace of senolytic drug candidates are forms of chemotherapeutic, already well characterized for human use as a result of cancer treatment trials, and their mechanisms of action comparatively well understood. If they can be used at lower dosages, at which the serious side-effects of cancer chemotherapy can be avoided, then we may well see responsible medical tourism for senescent cell clearance a couple of years from now. For those who want to wait for treatments with few to no side-effects, there is always the work being undertaken by Oisin Biotechnologies, which will likely follow on to clinics a few years thereafter.
Cellular senescence in osteoarthritis pathology
Osteoarthritis (OA) is the most prevalent disease of synovial joints (around 4.7% of global population for knee and hip OA alone), afflicting many millions worldwide with pain and disability, and thus represents an enormous healthcare and socioeconomic burden. Advancing age is a major risk factor, thus the burden of OA is set to increase dramatically as populations continue to age. A joint affected by OA exhibits progressive degeneration of the articular cartilage, formation of bony peripheral outgrowths (osteophytes), changes in subchondral bone and thickening of both the synovium and ligaments, and in many cases synovial inflammation (synovitis), which is thought to be an important driver of early pathology. Pathologic roles for multiple tissues in deteriorating joint function therefore define OA as a whole joint disease, driven by various biomechanical and inflammatory factors. There are currently no treatments available to effectively prevent or reverse progressive joint damage; therefore, new and innovative treatments are urgently required to improve treatment options. This will require continued improvements in our understanding of the molecular mechanisms underlying OA pathology.
Senescent cells secrete a variety of inflammatory cytokines, growth factors and many more soluble and insoluble factors known as the senescence-associated secretory phenotype (SASP). These factors are secreted into the cell microenvironment, with cytokines such as IL-6 and IL-8 enforcing the stable growth arrest of senescent cells. Various features of senescent cells, such as the SASP, can cause damage to surrounding tissue. SASP secreted by senescent cells can alter the tissue microenvironment, while the senescence of stem or progenitor cells can impair tissue regeneration. Over the past decade, many studies have linked cellular senescence to aging and age-related pathologies, thus leading to an overlap in research between the fields of disease processes and gerontology.
Although there are multiple joint tissues and cell types involved in OA pathology, chondrocytes have been the focus of the vast majority of studies to date that address a role for senescence. Chondrocytes are the only cell type present in articular cartilage, a highly specialized avascular and aneural tissue whose structural and mechanical properties are largely defined by the two predominant extracellular matrix (ECM) components, type II collagen, and aggrecan. Chondrocytes are responsible for producing and maintaining this ECM and receive nutrients and external chemical signals from the synovial fluid via secretions of fibroblast-like synoviocytes of the intimal synovial layer.
It is thought that cellular senescence may play a significant role in the pathology of OA, with OA chondrocytes exhibiting a variety of senescent-associated phenotypes. Despite recent traction for views of OA as a whole joint disease rather than merely dysfunctional cartilage, chondrocytes remain regarded as key players in OA pathology and are understood to exhibit during disease a perturbation of the normal balance between synthesis and degradation of extracellular matrix (ECM) components. This involves upregulating the production of matrix-degrading metalloproteinases such as MMP-13, exogenous activity of which was sufficient to recapitulate key OA features in mice. Senescence of chondrocytes would be expected to lead similarly to shifting of the balance between ECM synthesis and degradation, through metalloproteinase components of the SASP response.
Senotherapeutic agents are used to target specific properties of cellular senescence; more specifically, senolytics are used to target anti-apoptotic mechanisms and induce cell death within senescent cells. Senolytic drugs may therefore also be potentially used to provide an innovative therapeutic approach to treatment of various conditions. Dasatinib is currently used in the treatment of cancer. It is widely accepted that cancer cells and senescent cells share common anti-apoptotic characteristics, and the combination treatment of dasatinib and quercetin has already been observed to reduce the burden of senescent cells, as well as enhance cardiovascular function, in aged mice. We have reviewed a body of work that, taken together, strongly suggests that senescence could play a significant role in the pathogenesis of OA. Therefore, if dasatinib/quercetin combination therapy is effective in eliminating senescent cells, it could provide an extremely appealing therapeutic target for OA.
Extending Yeast Lifespan with Lithocholic Acid
A couple of interesting papers are doing the rounds, in which researchers report on a fivefold extension of yeast chronological life span through what they look on as an exercise in forced microevolution. They subjected yeast strains to an environment containing lithocholic acid, which is actually pretty unpleasant if you're a yeast cell, and allowed the yeast to adapt through generations. Few survived, and those that did survived through the acquisition of mutations that helped them resist the damaging effects of lithocholic acid. As it turns out, there is considerable overlap between mutations that help resist lithocholic acid and mutations that help resist the forms of damage that cause aging in yeast. As a result a number of the mutant lineages are stable and long-lived once the lithocholic acid is no longer present.
This is all quite interesting as a potential path to ranking the relevance of various repair and stress resistance mechanisms in cell aging, and as a way to obtain mutant lineages in which these mechanisms are enabled in potentially novel ways. Yeast are only somewhat multicellular, however, and thus one has to be careful in extrapolating information obtained on aging from yeast to animals. Since enhanced longevity through calorie restriction and cellular housekeeping mechanisms evolved very early on in the history of life, and since the underlying biological machinery is surprisingly similar in yeast and animals, yeast studies have proven very useful in understanding the ways in which cellular behavior changes in order to resist stress. There is no direct connection between cell life span and species life span, however, and when talking about yeast chronological age, it is the life span of a single cell that is under consideration.
Where the researchers overreach, I think, is in claiming that the observed outcome in microevolution argues strongly for programmed aging in macroevolution, in which aging is the result of a genetic program rather than an accumulation of biological wear and tear. It is perfectly possibly, however, to argue that their observations are in line with non-programmed aging theories in which aging is the result of damage accumulation; they have, after all, provided a way for cells to resist and repair damage to a greater degree than is usually possible through greater use of existing mechanisms. Further I'd say that the results at present are not necessarily at all relevant to the operation of macroevolution in the wild over longer periods of time, and again, the situation for single cells doesn't map directly to the situation for multicellular life.
As I understand it, there are views of the evolution of aging in which immortal species with unfettered reproduction are perfectly viable in and of themselves, but they will always be outcompeted in a changing environment by an aging species. Given the small number of mutations to produce yeast that lives five times longer than usual, why do we not see this yeast in the wild? We do not see immortals because they cannot exist, rather we do not see them because they are almost always quickly buried by their aging competitors whenever they do arise. Yet that apparently immortal animals can exist finds evidence in the absence of distinguishable aging in hydra, to pick the best known example. Even the negligible senescence observed in some species is somewhat challenging for the idea that long-lived organisms must necessarily grow more slowly and reproduce less efficiently than short-lived species.
Yeast mutants unlock the secrets of aging
The researchers exposed yeast to lithocholic acid, an aging-delaying natural molecule discovered in a previous study. In so doing, they created long-lived yeast mutants that they dubbed "yeast centenarians." These yeast mutants lived five times longer than their normal counterparts because their mitochondria - the part of the cell responsible for respiration and energy production - consumed more oxygen and produced more energy than in normal yeast. The centenarians were also much more resistant to oxidative damage, which is another process that causes aging. "This confirms that lithocholic acid, which occurs naturally in the environment, can not only delay yeast aging but can also force the evolution of exceptionally long-lived yeast."
The next step? Using yeast centenarians to test two types of aging theories: Programmed aging theories claim that organisms are genetically programmed to have a limited lifespan because aging serves some evolutionary purpose. That would mean that there are active mechanisms that cause aging and limit lifespan. Non-programmed aging theories contend that aging doesn't serve an evolutionary purpose. Therefore, an evolved mechanism whose main goal is to cause aging or limit lifespan simply cannot exist. What's more, non-programmed aging theories posit that any exceptionally long-lived organism must grow slower and reproduce less efficiently than an organism whose lifespan is limited at a certain age.
By producing long-lived yeast mutants and culturing them separately from normal yeast, the researchers were able to show that the centenarians grow and reproduce just as efficiently as the non-centenarians - thereby confirming programmed aging theories. "By confirming that there are active mechanisms limiting the longevity of any organism, we provided the first experimental evidence that such lifespan-limiting active mechanisms exist and can be manipulated by natural molecules to delay aging and improve health."
Empirical Validation of a Hypothesis of the Hormetic Selective Forces Driving the Evolution of Longevity Regulation Mechanisms
Exogenously added lithocholic bile acid and some other bile acids slow down yeast chronological aging by eliciting a hormetic stress response and altering mitochondrial functionality. Unlike animals, yeast cells do not synthesize bile acids. We therefore hypothesized that bile acids released into an ecosystem by animals may act as interspecies chemical signals that generate selective pressure for the evolution of longevity regulation mechanisms in yeast within this ecosystem. To empirically verify our hypothesis, in this study we carried out a three-step process for the selection of long-lived yeast species by a long-term exposure to exogenous lithocholic bile acid. Such experimental evolution yielded 20 long-lived mutants, three of which were capable of sustaining their considerably prolonged chronological lifespans after numerous passages in medium without lithocholic acid. The extended longevity of each of the three long-lived yeast species was a dominant polygenic trait caused by mutations in more than two nuclear genes. Each of the three mutants displayed considerable alterations to the age-related chronology of mitochondrial respiration and showed enhanced resistance to chronic oxidative, thermal, and osmotic stresses.
Our hypothesis posits the following: (1) only yeast exposed to exogenous bile acids can develop mechanisms of protection against cellular damage caused by these external stress agents and hormetic stimuli; (2) some of these mechanisms developed against bile acid-induced cellular damage can also protect yeast against damage and stress accumulated purely with age; (3) only those yeast species that have developed (due to exposure to exogenous bile acids) the most protective mechanisms against bile acid-induced cellular damage can also develop protective mechanisms against damage and stress accumulated with age; and (4) these yeast species are therefore expected to live longer. In this hypothesis, the presence of exogenous bile acids creates hormetic selective force that drives the evolution of not only protective mechanisms against bile acid-induced cellular damage but also longevity regulation mechanisms that protect against damage and stress accumulated with age. Moreover, this hypothesis suggests that yeast cells that are not exposed to exogenous bile acids cannot develop mechanisms of protection against cellular damage caused by these mildly toxic molecules. Thus, these yeast cells are unable to develop mechanisms of protection against damage and stress accumulated purely with age.
Empirical verification of evolutionary theories of aging
We recently selected 3 long-lived mutant strains of Saccharomyces cerevisiae by a lasting exposure to exogenous lithocholic acid. Each mutant strain can maintain the extended chronological lifespan after numerous passages in medium without lithocholic acid. In this study, we used these long-lived yeast mutants for empirical verification of evolutionary theories of aging. We provide evidence that the dominant polygenic trait extending longevity of each of these mutants 1) does not affect such key features of early-life fitness as the exponential growth rate, efficacy of post-exponential growth and fecundity; and 2) enhances such features of early-life fitness as susceptibility to chronic exogenous stresses, and the resistance to apoptotic and liponecrotic forms of programmed cell death.
These findings validate evolutionary theories of programmed aging. We also demonstrate that under laboratory conditions that imitate the process of natural selection within an ecosystem, each of these long-lived mutant strains is forced out of the ecosystem by the parental wild-type strain exhibiting shorter lifespan. We therefore concluded that yeast cells have evolved some mechanisms for limiting their lifespan upon reaching a certain chronological age. These mechanisms drive the evolution of yeast longevity towards maintaining a finite yeast chronological lifespan within ecosystems.
Rejuvenation Biotechnology Update for January 2017
The Methuselah Foundation and SENS Research Foundation have sent around the latest edition of the Rejuvenation Biotechnology Update, highlighting and explaining a few of the more interesting research results of recent months. It is a quarterly newsletter for members of the Methuselah 300, a more than decade-old group of advocates and supporters who each pledge to donate 25,000 over 25 years to help fund the development of therapies to treat aging. The first of the 300 helped to launch the Methuselah Foundation, and their continued support drew in the funding needed to eventually spin off the SENS Research Foundation as its own venture. While it was just thirteen years ago that the 300 was first mentioned, a lot has happened since then. Tempus fugit.
Only thirteen years, yes, but for me that seems like a long time past. Back then advocates for longevity science were few in number, working so very hard to raise a few thousand here and a few thousand there, while being roundly mocked for declaring that aging should and could be treated as a medical condition when people did deign to pay attention. How far we've come since then! The entire environment has changed, the attitudes of the scientific establishment are remade, the concept of medicine to address aging is discussed in the media on a regular basis, available funding is greatly multiplied, and the first SENS rejuvenation therapies are moving towards the clinic. There is a still a long way to go yet towards the goal of defeating aging and all age-related disease, but the beginning has been written and done: we have now entered into the next phase.
Rejuvenation Biotechnology Update, January 2017 (PDF)
Transplanted Senescent Cells Induce an Osteoarthritis-Like Condition in Mice.
This study provides evidence that adding senescent cells to a healthy joint can create a constellation of symptoms that resemble osteoarthritis. It is an important step in linking cellular senescence and osteoarthritic joint damage. However, the "smoking gun" that would really implicate senescent cells as a clinically-relevant target for osteoarthritis treatment would be to demonstrate that using senolytic drugs or genetic approaches to remove senescent cells from the joint of an animal with osteoarthritis leads to an improvement in osteoarthritis symptoms and the restoration of joint structure and function. Furthermore, the authors acknowledge that senescent cells may be one cause or a contributor to osteoarthritis, but osteoarthritis may also have other causes or contributing factors (such as chronic inflammation from other causes, mitochondrial dysfunction, and loss of glycosaminoglycans). So, we remain vigilant about the potentially-significant role of senescent cells is in the development of osteoarthritis.
Given that it is becoming increasingly clear that senescent cells significantly contribute to an overall phenotype of age-associated disease and dysfunction, these results are a promising step in the direction of implicating senescent cells as a therapeutic target for osteoarthritis. These findings no doubt hearten our colleagues at UNITY Biotechnology, who have identified osteoarthritis as their first target for senolytic drug therapy. Research on clearance of senescent cells as a strategy to correct aging damage is a high priority to SENS Research Foundation and Methuselah Foundation. Fortunately, this field seems to be advancing significantly and rapidly in the last few years. The company Oisín Biotechnologies (partially funded by SENS Research Foundation and Methuselah Foundation) is pursuing a "transient" (non-integrating) genetic approach to target and remove senescent cells from human bodies.
A single heterochronic blood exchange reveals rapid inhibition of multiple tissues by old blood.
This study represents an important advancement in technology to study blood-borne factors associated with youth and aging. It also contributes important findings that isolate the effect of blood-borne factors on tissue functions and injury repair in the context of aging. The authors anticipated that when the effects of blood alone were isolated, the findings would more relevant to human clinical applications. Some key findings from this study were that, at least when it came to neurogenesis, old blood seemed to inhibit neurogenesis more in young mice than young blood rejuvenated the brains of old mice. This would seem to implicate a greater increase in pro-aging factors, compared to the decrease in anti-aging factors, with age. This finding of old blood inhibiting neurogenesis in the hippocampus may be linked with the observed increase in β-2 microglobulin in young mice who received old blood, which occurred in the brain and muscle. However, the exact mechanism by which β-2 microglobulin levels came to be elevated in young mice who received old blood is still not clear. If it could be clarified, perhaps a potential therapeutic target or targets could be identified to lower β-2 microglobulin and other pro-aging factor levels in aged individuals.
One especially encouraging finding from this study was, as the authors put it, "the plasticity of age" - the observation that changes in tissues took place rapidly and old tissues were restored to a more youthful state within days of when blood exchange took place. And, unlike parabiosis experiments, a therapeutic approach based on blood exchange or blood filtration would be feasible in humans. Exchange transfusion is already an established treatment for several human autoimmune diseases where diluting auto-antibodies out of the circulation is beneficial, and exchange transfusion devices are currently available and FDA-approved for treatment of these diseases. Similarly, hemodialysis is a well-established procedure, and a more selective device that would scrub old blood of excessive "pro-aging" factors could extend this paradigm. The investigators in this study are looking to develop their findings into a clinical application for human patients soon: a startup company founded by a colleague is now preparing a clinical trial to adapt existing medical equipment test this very possibility in aging humans.
Vestibular Perceptual Thresholds Increase above the Age of 40.
The vestibular system in humans senses body motion and positioning of the body in space. The vestibular apparatus in the inner ear consists of a fluid-filled organ lined with sensing cells. The study found that after age 40, in both males and females, vestibular function steadily declined: vestibular perceptual thresholds increased; that is, the older a person gets, the more movement it takes for them to detect a change in position. According to the CDC, 1 out of 4 older Americans falls each year. In older individuals, falling is strongly associated with serious injuries and death. In fact, falls are the leading cause of injury and death from injury in Americans over age 65. The major factors for avoiding falls are functional balance and leg strength. The vestibular system plays a critical role in balance. So, understanding age-related declines in vestibular function may reveal critical insights into how to maintain balance and prevent falls.
Unfortunately, the major thing missing from this study was the identification of a mechanism for the decline in vestibular function after approximately age 40, and evidence supporting the identification of this mechanism. Several other studies have measured the number of vestibular hair cells (sensory cells) at various ages and showed a steady decline every year since birth. At first glance, this data does not seem to fit with the observation that vestibular function only starts to decline after age 40, this may be a case of a common phenomenon in aging that Dr. Aubrey de Grey has referred to as the "threshold of pathology." That is, humans may have enough vestibular hair cells so as to be redundant before age 40. Beyond that age, they may have lost enough cells that vestibular function starts to be affected as more cells die off. The authors speculate that free radical damage may be responsible for the death of vestibular hair cells with age, and further that vestibular function may serve as a reliable marker for the level of aging damage an individual has incurred, which can be measured noninvasively by simply testing vestibular function as they did in the current study.
Although the authors do not have experimental evidence that free radical damage is responsible for declining vestibular function with age, there is a range of evidence supporting the involvement of mutations in mitochondrial DNA and of mitochondrial free radical generation in vestibular damage from other causes. Vestibular damage is a major side-effect of the antibiotic gentamycin and others in its class, and free radicals are thought to be one of the mechanisms. Moreover, people with specific mutations in mitochondrial genes that code for the organelles that assemble proteins that are components of the mitochondrial energy production machinery are unusually vulnerable to this toxicity. Mice with a mutation that prevents the building of one of the complexes of the mitochondrial energy-production line develop vestibular damage, and human patients with the mitochondrial mutation disease Kearns-Sayre syndrome frequently have vestibular dysfunction as one of the many effects of the disease.
One way to address the rise in free radical damage with age is to prevent it at the source. This is the strategy behind SENS Research Foundation's "MitoSENS" program. Briefly: mitochondria in a subset of cells acquire large deletions in their DNA as individuals age, and the abnormal metabolic activity that cells harboring such mitochondria undertake results in a rise in oxidative stress in the body. To fix this problem, mitochondrial genes should be stably expressed in the cell nucleus instead of in the mitochondria, where these genes are more easily damaged. The strategy of MitoSENS is to fix the source of the damage: the inability of these dysfunctional mitochondria to generate the proteins they need to carry out normal metabolism with lower free radical production. If vestibular function is indeed connected to the rise of cells that have been taken over by mitochondria bearing such deletions and creating additional free radicals, this would enhance the value of the goals of the MitoSENS project, which could provide the benefit of preserving vestibular function and prevent the common, dangerous, and deadly scourge of falls.
Building a Better Cellular Senescence Assay: LongeCity Puts Forward a 3000 Matching Challenge for the CellAge Fundraiser
CellAge is seeking philanthropic funding to build a better class of assay for senescent cell presence in tissues, a technology they plan to make freely available to academic researchers if successful in their efforts. Present assays for cellular senescence are well-established, some little changed for two decades, but are by now somewhat clunky and behind the times. They suffice for research and development, but are not a good basis for the coming future of low-cost, reliable clinical tests. An increase in the numbers of senescent cells throughout the body is one of the root causes of degenerative aging. Given the broad influence of cellular senescence in aging and many age-related conditions, with new evidence for this influence arriving every month these days, I would think that everyone should be assayed as a matter of course, a part of any sensible health checkup. Unfortunately, that would be hard to do today at a reasonable cost, even assuming you could find a company offering the service. The need for better assays will only increase as senolytic therapies of various sorts become available via medical tourism, and later in clinics in the US and Europe. If underging a treatment that removes senescent cells, then one would certainly want a reliable method of proving that it worked.
I have been speaking with the CellAge principals of late to work on other possibilities for funding, and help them to make some potentially useful connections within the community. That effort moves along at its own slow pace behind the scenes; it always takes a while to find out whether or not matters can be lined up to a useful conclusion, and then there is the separate undertaking of actually moving ahead to make that conclusion happen. Meanwhile, every additional helping hand makes things that much easier. Thus I am most pleased to note that the LongeCity community has put up a 3000 matching fund to help spur donations to the present crowdfunding initiative. They have sensibly made this a part of their existing program for funding discrete scientific projects, and picked out one portion of the necessary work at CellAge that will produce a useful outcome for the research community even standing alone. Good for them.
CellAge fundraiser support
LongeCity.Org has decided to support the current CellAge Fundraiser initiative beyond its standard support for certified 'star-rated' community fundraiser through an extension of its affiliate lab programme. To this end we have identified a specific small 'sub goal' within the first work project of the CellAge programme to get behind: The first 'work project' of the CellAge fundraiser is to design candidate synthetic promoters which would be able to accurately detect senescent cells. One of the very first scientific steps is to analyse transcription profiles of senescent cells. The team plans to cover different senescence states, in cells from different tissues and at different stage of senescence. The LongeCity target fund is raised in support of achieving one variant of this initial sub-goal: to ascertain the unique RNA profile of induced senescence in human fibroblasts.
By clearly defining the boundaries of this sub-goal we can be assured that contributions made towards it are directly impactful. In fact, even if the whole project should need some more time to develop, just this sub-goal alone might be a valuable contribution to anti-aging research. At the same time all the data generated in the sub-goal is directly integral to the larger whole of the project. LongeCity has committed to match 3000 worth of donations specifically in support of this sub-goal. Priority will be given to donations made through the LongeCity site, prior to February 18th.
Longecity Fund Match Announced For CellAge Campaign
Hello, dear friends! So far we have raised over 14,000 in funding for the CellAge campaign! There are 22 days left before the campaign ends, and it is time to make another push towards the victory line. Also we have an exciting announcement: the CellAge project is now endorsed by LongeCity, one of the oldest international pro-longevity organizations. Their forum represents an exclusive education platform that has helped thousands of people learn about the endeavor to bring aging processes under medical control, remain informed about the latest breakthroughs, and develop their own strategy of health maintenance.
The LongeCity community has certified this important research project to target and remove harmful senescent cells, and is contributing 800 right away. They are also running an internal fund match: anything donated at LongeCity before February, 18 will be doubled up to 3000, and then the whole amount will be sent to support CellAge campaign on Lifespan.io. Donations made this way will still be eligible for corresponding Lifespan.io rewards, so don't hold back! You are very welcome to contribute, and please remember that every donatation made at LongeCity is doubled - and the project will receive a nice push to get us to our goal: control over senescent cells!
Biologically Modified Justice
Long time readers no doubt already know that I'm not much in favor of social justice as it is practiced and advocated these days. Just like Marxist communism or other forms of idealized socialism, the concepts sound great when presented in the philosophical abstract, detached from the process of actually running an implementation through the messy reality of human nature and human society. Unfortunately, in practice you wind up with things like the millions of deaths in the old Soviet Union, the sad state of Venezuela today, and in the wealthier and more successful parts of world, a substantial fraction of society who would read Harrison Bergeron as something other than satire. Charity is a wonderful thing. Forcing other people into your choice of charity with the threat of imprisonment and violence, less so. Similarly for dragging down the best and the brightest and the most entrepreneurial, those who are working to build the better tomorrow. If you press them into doing nothing more than supporting mediocrity and paying for the consequences of failure, then the future will be one of far more mediocrity and failure, not progress.
So that said, today I thought I'd point out Biologically Modified Justice, a book written by an academic who is very much in favor of both social justice and bringing an end to aging and age-related disease. I linked to his blog here and there back when he was writing regularly on the topic of longevity science; it was interesting to observe someone within a community traditionally hostile towards life extension - and to technological progress in general, for that matter - reconciling the urge to personal health and longevity with a doctrine that proclaims any such urge for self-improvement as somewhere between selfish and evil. A widespread view among many of the social justice community, insofar as we can put a single label on a very broad collection of diverse viewpoints, is that progress must start by raising up the weakest and poorest. Attempts to build new technologies always benefit the wealthy and the influential first of all, and are thus either viewed with suspicion or vetoed outright, even given the history of countless initially expensive technologies that rapidly became available for the masses at a low cost. Those who throw stones at the altar of inequality wish for a society more level, and often at any cost to progress.
Fortunately there are more sensible voices, such as the author of the book linked below, though I fear they often have little influence over what passes for the mainstream of thinking regarding social justice, and sensible or not, even their more polite views are still footsteps on the same road that led to the Soviet Union and Venezuela. Human nature and enforced equality are just not compatible housemates. Still, I think most of you would find Biologically Modified Justice an interesting read, regardless of your leanings on the optimal organization of human society. As the biotechnologies of human rejuvenation move closer to widespread availability in the clinic, we are going to see many new voices in favor of rejuvenation arise in communities that are at this time generally hostile towards progress and enhanced longevity. There will be numerous attempts to synthesis the urge to live longer, and the advent of the means to do so, with philosophies that presently reject that goal. These are interesting times.
Biologically Modified Justice
Theories of distributive justice tend to focus on the issue of what constitutes a fair division of 'external' goods and opportunities; things like wealth and income, opportunities for education and basic liberties and rights. However, rapid advances in the biomedical sciences have ushered in a new era, one where the 'genetic lottery of life' can be directly influenced by humans in ways that would have been considered science fiction only a few decades ago. How should theories of justice be modified to take seriously the prospect of new biotechnologies, especially given the health challenges posed by global aging? Biologically Modified Justice addresses a host of topics, ranging from gene therapy and preimplantation genetic diagnosis, to an 'anti-aging' intervention and the creation and evolution of patriarchy. This book aims to foster the interdisciplinary dialogue needed to ensure we think rationally and cogently about science and science policy in the twenty-first century.
The idea that we could directly alter the biology of a person via genetic intervention, or develop an 'anti-aging drug', or utilize genetic tests for screening genetic diseases would have been considered pure science fiction just a few decades ago. And yet all of these prospects either have become, or might soon be, a reality. And as science progresses we may be able to promote the health prospects of the current generation (and all future generations) by improving our biological capacity to fend off infectious and chronic diseases. I began working on this book in the year 2000. That was the same year two rival teams were racing to sequence the human genome. As I began to follow the field of human genetics, and to think about the importance of science more generally, I realized that there was very little written by political theorists on these topics. Over the years the neglect of science, especially the biomedical sicences, began to trouble me more and more. It troubled me both as a teacher and as a scholar.
As a teacher I found it disturbing that my students learned about topics such as justice, freedom, and equality but did not really learn about the important role science and innovation play in helping humanity create more fair and humane societies. Current debates about distributive justice often give students the impression that justice only involves the distribution of wealth and income, or giving priority to basic liberties like free speech. But government decisions to stifle or promote basic and applied scientific research can also have profound impacts on our life prospects. What constitutes 'well-ordered' science? Would we know unjust science policies when we see them? Neglecting these issues comes with great peril, as many of the most pressing challenges humanity faces this century will require new knowledge and innovation.
Rather than simply extending existing theories of justice to encompass the new developments of the genetic revolution, I came to the conclusion that the genetic revolution that was unfolding around us required political theorists to re-think the basic premises of what the demands of justice are, as well as what we wanted or expected from our theories of justice. Can insights from evolutionary biology and genetics help the political theorist develop emancipatory knowledge about the kind of society, institutions, and culture we should aspire to realize in the world today? I decided to write this book because I believe the answer to this question is an emphatic 'Yes!'
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International Longevity and Cryopreservation Summit in Spain, May 2017
Members of the Spanish longevity science and cryonics communities have organized a conference to be held later this year in Barcelona, Madrid, and Seville. Good for them; it is always pleasant to see the various regional groups of our broader community growing in sophistication and reach. Advocacy and publicity for the cause of radical life extension moves forward one modest step at a time. The more that we talk to the public and the more that we work to build larger networks of supporters, the closer we move towards the realization of technologies that can extend healthy life spans. Further, the cryonics industry remains small enough at this time to benefit considerably from greater efforts to draw together the groups of supporters that exist in numerous countries around the world. We can hope that such an initiative will lead in time to the successful foundation of new cryonics service and support companies outside the US, an evolution of the industry that is long overdue.
Spain will host the first International Longevity and Cryopreservation Summit during May 26-28, 2017. Fundacion VidaPlus will be the main organizer of this world congress, with the help of other leading associations and organizations working on longevity, indefinite lifespans, cryopreservation, and other biomedical areas. Longevity extension has been one of the dreams of humanity since the beginning of recorded history. Even starting the 20th Century average lifespans were just about 40 years in the first industrial nations, and starting the 21st Century average lifespans have doubled again to around 80 years in the most advanced countries. The possibility of doubling again lifespans is increasing rapidly again thanks to exponential technologies and new medical research and development. On a parallel front, cryonics has also advanced considerably since the first spermatozoids were frozen and successfully reanimated about half a century ago. Then followed eggs, embryos, many tissues and complete organs, in different kinds of animals, including some small mammals. What will the future bring? Science and technology should lead the way!
Several institutions have been advancing research on longevity extension, from governments to private companies. Institutions like the Life Extension Foundation and the SENS Research Foundation, to name just two, have been pioneers in promoting investigations and applications on human longevity extension. Additionally, the two major US cryonics institutions, Alcor Life Extension Foundation and Cryonics Institute, have been holding successful regular meetings for their members and other insterested audiences during the last four decades. In Europe, there was an initial regional meeting in Goslar (Germany) in 2010, followed by Dresden (Germany) in 2014, Utrecht (Netherlands) in 2015, and then Basel (Switzerland) in 2016. KrioRus has also been promoting cryonics in Russia and other countries.
Now we are planning to host in Spain the first International Longevity and Cryonics Summit open to people from all continents, with participants coming from the United States to the United Kingdom, from Argentina to Australia, from Africa to China, from Russia to Venezuela. The topics considered will be very broad, ranging from recent medical advances to human cryopreservation. Spain will become the meeting point for this first summit, where there are plans to create an International Cryonics Society to gather and accredit the different groups working around the world. The first part of the May events will be the international congress in English during the weekend of May 27-28 in Madrid, followed by national events in Spanish on May 29 in Madrid, May 30 in Barcelona, and May 31 in Seville. The objective is to combine the international reunions with local audiences and to help promote longevity and cryonics research and development in Spain.
Human Longevity Variations are Largely Due to Unknown Genetic and Environment Differences or Simple Chance?
A spread in the longevity of similar individuals is a feature of any collection of demographic data. Are these variations simply random, a matter of luck and happenstance, or do they reflect underlying genetic or environment differences that are presently only poorly understood, absent in the data recorded for each individual? In other words, how much of natural variation in human longevity has been explained by the research community, and its causes identified, at least to a first approximation? Are there significant differences between individuals yet to be understood? It is possible to use statistical techniques to identify the relative contributions of distinct classes of influence on these variations in longevity, and here, researchers replicate past findings by showing that hidden differences between individuals likely account for little of the observed variation in human longevity. This suggests that there are probably no very large surprises ahead of us when it comes to understanding influences on aging in our species.
Individual variance, especially in fitness components, plays a key role in demography, ecology, and evolutionary biology. From an evolutionary perspective, variance in fitness components is potential material on which natural selection can operate. Longevity (age at death) is a fitness component that varies widely among individuals. This variance arises as a result of two different underlying causes: individual stochasticity and heterogeneity.
Individual stochasticity is variance due to random outcomes of probabilistic demographic processes (living or dying, reproducing or not, making or not making a life cycle transition). Even in a completely homogeneous population, in which every individual experienced exactly the same (age-specific) mortality rates, variance due to individual stochasticity would exist. Any calculation of the variance in longevity from an ordinary life table implicitly assumes that every individual is subject to the (age-specific) mortality rates in that life table, and hence that the variance is only due to individual stochasticity.
Variance in longevity can also result from unobserved, or latent, heterogeneity in the properties of individuals. For example, individuals of the same age may differ in their mortality rates due to genetic, environmental, or maternal effects. Such differences are often referred to as heterogeneity in individual frailty. Because more frail individuals are more at risk than others, heterogeneity in frailty leads to changes in cohort composition with age, due to within-cohort selection. As a cohort ages, the representation of less frail individuals increases, and the average mortality rate in an old cohort will be lower than one would expect based on extrapolation of mortality rates at younger ages. This selection effect has been suggested as an explanation for the mortality plateaus often observed at very old ages.
The effects of unobserved heterogeneity in survival analysis can be estimated using frailty models. In frailty models, a baseline mortality schedule is modified by a term representing individual frailty. The variance in longevity in a frailty model is a result of both stochasticity and heterogeneity. Little is known about the relative contribution of each to the total variance in longevity, and how those contributions may depend on species, sex, environmental conditions, etc. Other researchers have presented an ad hoc approach to this problem: the relative contributions of heterogeneity and stochasticity were estimated by reducing the initial variance in frailty to zero and attributing the remaining longevity variance to stochasticity. In an analysis of Swedish females, the fraction of variance due to heterogeneity was estimated to be only 0.071. Applying the same approach to a model for women from Turin resulted in an even lower estimate of 0.012.
Here, we present a more rigorous model. The variance due to individual stochasticity can be calculated from a Markov chain description of the life cycle. The variance due to heterogeneity can be calculated from a multistate model that incorporates the heterogeneity. We show how to use this approach to decompose the variance in longevity into contributions from stochasticity and heterogeneous frailty for male and female cohorts from Sweden (1751-1899), France (1816-1903), and Italy (1872-1899), and also for a selection of period data for the same countries. The results were consistent between countries and sexes: most of this variance in remaining longevity is due to stochasticity. Only a small fraction is attributable to heterogeneity. This fraction increases with starting age, because stochasticity-induced variance decreases faster with age than does heterogeneity-induced variance. However, even conditioning on survival to a starting age of 70 years, the average fraction due to heterogeneity is less than 0.10 (for cohort mortality) or 0.15 (for period mortality). Although data quality is, for obvious reasons, better for later cohorts and periods than for earlier ones, we found no clear temporal patterns in the fraction of variance due to heterogeneity.
Targeting PAD4 Reduces Age-Related Fibrosis
Fibrosis is the inappropriate formation of scar-like tissue, and it is an important component in the pathology of a range of age-related diseases. Fibrosis causes loss of function where it disrupts the normal tissue structure of organs, and at present there is little in the medical toolkit that can be used to help. Better known examples of conditions in which fibrosis is significant include the progression of chronic kidney disease and damage to aged heart tissue. Here researchers note the possibility for an intervention that slows down the progression of fibrosis in mice, and may form the basis for a human therapy:
The wear and tear of life takes a cumulative toll on our bodies. Our organs gradually stiffen through fibrosis, which is a process that deposits tough collagen in our body tissue. Fibrosis happens little by little, each time we experience illness or injury. Eventually, this causes our health to decline. Ironically, fibrosis can stem from our own immune system's attempt to defend us during injury, stress-related illness, environmental factors and even common infections. But a team of scientists thinks preventative therapies could be on the horizon. "We've documented in mice how deletion of a single gene, PAD4, has a drastic effect on curbing the complex process of fibrosis." Looking to the future, they envision that the development of a once-daily pill, capable of inhibiting PAD4, could one day be used as a preventative measure.
The PAD4 gene controls an enzyme of the same name. In times of infection or bodily stress, the PAD4 enzyme activates a strange, primitive immune defense that ends up doing more harm than good. White blood cells, called neutrophils, self-combust and eject their own DNA strands outward like javelins. Sacrificing themselves, the exploded neutrophils and their outreaching DNA tentacles form so-called neutrophil extracellular traps (NETs), which nature perhaps intended to use as webs for catching foreign invaders and plugging up injury-related bleeding. Even though NETs try to help us, they counteractively set off a chain reaction that deposits an insidious type of collagen amidst our organs' hard-working cells. This collagen-laced fibrosis keeps piling up each time our body's immune system releases NETs. Over a lifetime, cumulative fibrosis is a far more important factor in health than any possible benefits imparted by NET release.
Whereas young hearts in mice and humans contain thin layers of connective tissue, older hearts typically have too much connective collagen built up between heart muscle cells. This reduces the heart's ability to pump blood efficiently. To investigate PAD4's effects on age-related cardiac fibrosis, researchers compared heart tissue of normal mice with another group of mice that had the PAD4 gene deleted. They observed that old mice without PAD4 had much less fibrosis than the normal mice. In fact, these mice had heart tissue that looked strikingly similar to heart tissue of young mice, and they kept up remarkably "young" levels of systolic and diastolic heart function as they aged. Researchers then looked at collagen deposition in mouse lungs. They found that deleting the PAD4 gene also significantly reduced lung fibrosis as mice aged. The researchers believe these observations show that deleting the PAD4 gene in mice protected their organs from age-related fibrosis and dysfunction. "If we could inhibit PAD4 or otherwise stop NET release in humans, we might be able to greatly reduce age-related fibrosis and improve our quality of life."
A Role for Pericyte Dysfunction in Neurodegenerative Conditions
Researchers here investigate dysfunction of the class of cells known as pericytes that surround small blood vessels. These cells regulate blood flow, and in the brain support the blood-brain barrier, among other activities. Like all aspects of our cellular machinery, pericytes suffer damage, reduced function, and greater levels of cell death with advancing age. The open question, as is usually the case, is where this fits in the lengthy chain of of cause and consequence that leads from fundamental cellular damage and waste accumulation of the types outlined in the SENS rejuvenation research materials to specific age-related disease and disability.
A new study is the first to use a pericyte-deficient mouse model to test how blood flow is regulated in the brain. The goal was to identify whether pericytes could be an important new therapeutic target for treating neuron deterioration. "Pericyte degeneration may be ground zero for neurodegenerative disorders like Alzheimer's disease, ALS and possibly others. A glitch with gatekeeper cells that surround capillaries may restrict blood and oxygen supply to active areas of the brain, gradually causing neuron loss that might have important implications for Alzheimer's disease. Vascular problems increase the risk of cognitive impairment in many types of dementia, including Alzheimer's disease. Pericytes play an important part in keeping your brain healthy."
To test the theory, researchers stimulated the hind limb of young mice deficient in gatekeeper cells and monitored the global and individual responses of brain capillaries, the smallest blood vessels in the brain. The global cerebral blood flow response to an electric stimulus was reduced by about 30 percent compared to normal mice, denoting a weakened system. Relative to the control group, the capillaries of pericyte-deficient mice took 6.5 seconds longer to dilate. Slower capillary widening and a slower flow of red blood cells carrying oxygen through capillaries means it takes longer for the brain to get its fuel. As the mice turned 6 to 8 months old, global cerebral blood flow responses to stimuli progressively worsened. Blood flow responses for the experimental group were 58 percent lower than that of their age-matched peers. In short, with age, the brain's malfunctioning vascular system exponentially worsens.
"We now understand the function of blood vessel gatekeeper cells is to ensure adequate oxygen and energy supply to brain cells. Prior to our study, scientists knew patients with Alzheimer's disease, ALS and other neurodegenerative disorders experience changes to the blood flow and oxygen being supplied to the brain and that pericytes die. Our study adds a new piece of information: Loss of these gatekeeper cells leads to impaired blood flow and insufficient oxygen delivery to the brain. The big mystery now is: What kills pericytes in Alzheimer's disease?" Scientists are already working to further this line of research, scanning the brains of people who are genetically at risk for Alzheimer's. They are also collecting cerebral spinal fluid and blood for analysis of vascular damage, including injury to pericytes.
Glucose Deprivation in Alzheimer's Disease Progression
The progression of Alzheimer's disease, happening in the midst of aging in general, and often other unrelated neurodegeneration as well, is so complex and sweeping that every research group focuses down on just one part of the whole. It is like the parable of the elephant and the blind men, and has made it perhaps more challenging than it might otherwise be to understand and target root causes rather than intermediary, downstream processes in the pathology of the condition. You might look at yesterday's thoughts on Alzheimer's as a consequence of lack of oxygen in brain tissues and compare with this view of Alzheimer's as a lack of glucose, for example. These are just small pieces of a bigger picture, in a field in which there needs to be a lot more synthesis of disparate research into a uniform whole.
One of the earliest signs of Alzheimer's disease is a decline in glucose levels in the brain. It appears in the early stages of mild cognitive impairment - before symptoms of memory problems begin to surface. Whether it is a cause or consequence of neurological dysfunction has been unclear, but new research now shows unequivocally that glucose deprivation in the brain triggers the onset of cognitive decline, memory impairment in particular. The hippocampus plays a key role in processing and storing memories. It and other regions of the brain, however, rely exclusively on glucose for fuel - without glucose, neurons starve and eventually die.
The new study is the first to directly link memory impairment to glucose deprivation in the brain specifically through a mechanism involving the accumulation of a protein known as phosphorylated tau. Phosphorylated tau precipitates and aggregates in the brain, forming tangles and inducing neuronal death. In general, a greater abundance of tau tangles is associated with more severe dementia. The study also is the first to identify a protein known as p38 as a potential alternate drug target in the treatment of Alzheimer's disease. Neurons activate p38 protein in response to glucose deprivation, possibly as a defensive mechanism. In the long run, however, its activation increases tau phosphorylation, making the problem worse.
To investigate the impact of glucose deprivation on the brain, researchers used a mouse model that recapitulates memory impairments and tau pathology in Alzheimer's disease. At about 4 or 5 months of age, some of the animals were treated with 2-deoxyglucose (DG), a compound that stops glucose from entering and being utilized by cells. The compound was administered to the mice in a chronic manner, over a period of several months. The animals were then evaluated for cognitive function. In a series of maze tests to assess memory, glucose-deprived mice performed significantly worse than their untreated counterparts. When examined microscopically, neurons in the brains of DG-treated mice exhibited abnormal synaptic function, suggesting that neural communication pathways had broken down. Of particular consequence was a significant reduction in long-term potentiation - the mechanism that strengthens synaptic connections to ensure memory formation and storage.
Upon further examination, the researchers discovered high levels of phosphorylated tau and dramatically increased amounts of cell death in the brains of glucose-deprived mice. To find out why, researchers turned to p38, which in earlier work his team had identified as a driver of tau phosphorylation. In the new study, they found that memory impairment was directly associated with increased p38 activation. The findings also lend support to the idea that chronically occurring, small episodes of glucose deprivation are damaging for the brain. The next step is to inhibit p38 to see if memory impairments can be alleviated, despite glucose deprivation.
In Search of Lipid Signatures of Longevity in Mammalian Species
The research here makes a good companion piece to older work in which scientists correlate the lipid composition of cell membranes to species longevity, in the course of evaluating what is known as the membrane pacemaker hypothesis. Among other things, this points to the significance of mitochondrial function and mitochondrial damage in aging, given that, all other things being equal, species characterized by more resilient mitochondrial structures appear to live longer. This is probably far from the only reason why there might be specific lipid signatures associated with longer-lived or shorter-lived species, however.
In contrast to average life expectancy that may change depending on living conditions, maximal lifespan (MLS) is a stable characteristic of a species. At the same time, MLS varies greatly among species. In mammals it ranges from 3-4 years in small rodents to as long as 150-200 years in bowhead whales. More remarkably, MLS evolves rapidly, resulting in markedly different lifespans and, consequently, different time of aging onset, even among closely related species. For instance, humans and macaques diverged only around 30 million years ago (MYA), yet over this time their MLS has diverged as much as three-fold.
Despite remarkable evolutionary plasticity of MLS, the existence and nature of the molecular mechanisms controlling this variation remains unclear. Most studies so far have focused on mechanisms of lifespan plasticity within species, resulting in identification of longevity-related pathways, such as insulin signaling pathways and targets of rapamycin pathway, shared across a wide range of animal species: from worms to mice. Genetic, dietary and pharmacological manipulation targeting these pathways resulted in more than 10-fold lifespan extension in short-living nematode worms, but only approximately 40% (1.4-fold) lifespan extension in short-living mammals such as laboratory mice. At the same time, natural variation in MLS among mammalian species exceeds 50-fold.
In this study we searched for a link between MLS and another marker of species' physiology - concentrations of hydrophobic metabolic compounds (henceforth referred to as "lipids" for simplicity). Recent scans of gene expression variation among 33 mammalian species with MLS differences of over 30-fold has shown that expression variation of 11-18% of analyzed 19,643 genes could be associated with MLS variation. There is however a stronger evidence of genetic changes in genes controlling lipid metabolism to play a role in human longevity, as well as in MLS differences among species, and changes in lipid saturation levels, pointing to lipids as a good potential target for investigation of molecular mechanisms underlying differences in MLS among mammalian species.
Our results show that long lifespan is associated with distinct lipidome features shared across three mammalian clades. Lipid predictors of long MLS differ across tissues, but overlap within brain and non-neural tissue types. The long MLS predictors identified in brain are especially conserved among clades, allowing long-living species identification within a clade solely based on lipid predictors from the other two clades. While little can be said about functional significance of these changes one potentially important feature stands out: the genomes of long-living primate and rodent species show increased evolutionary selection acting upon the amino acid sequences of enzymes linked to lipid predictors of long MLS. These enzymes cluster in specific functional categories associated with signaling and protein modification processes, as well as the corresponding cellular compartments: Golgi apparatus and plasma membrane.
More Results for the Use of Immune System Reconstruction to Treat Autoimmunity
More evidence is accumulating to show that autoimmune diseases might be effectively treated by destroying the existing population of immune cells and then recreating them: the problem lies in the configuration and memory of those cells. The challenge in this is that, at present, the methods of destruction are harsh, akin to chemotherapy and certainly not something people would want to undergo for any but the most dangerous autoimmune conditions. A priority for the next few years is to find ways to selectively destroy immune cells safely and with few to no side-effects, at which point this type of immune reconstruction would be a very useful treatment for even minor autoimmunities. More pertinently, it would also open the door for the treatment of age-related dysfunction and failure of the immune system, a large component of the frailty of old age. Much of this decline is related to the accumulation of malfunctioning cells, or cells uselessly specialized to persistent pathogens like cytomegalovirus. If the slate could be wiped clean, we might expect there to be considerable improvement in immune response, even given the greater level of damage in cells and tissues characteristic of old age.
New clinical trial results provide evidence that high-dose immunosuppressive therapy followed by transplantation of a person's own blood-forming stem cells can induce sustained remission of relapsing-remitting multiple sclerosis (MS), an autoimmune disease in which the immune system attacks the central nervous system. Five years after receiving the treatment, called high-dose immunosuppressive therapy and autologous hematopoietic cell transplant (HDIT/HCT), 69 percent of trial participants had survived without experiencing progression of disability, relapse of MS symptoms or new brain lesions. Notably, participants did not take any MS medications after receiving HDIT/HCT. Other studies have indicated that currently available MS drugs have lower success rates.
In the HALT-MS trial, researchers tested the safety, efficacy and durability of HDIT/HCT in 24 volunteers aged 26 to 52 years with relapsing-remitting MS who, despite taking clinically available medications, experienced active inflammation, evidenced by frequent severe relapses, and worsened neurological disability. The experimental treatment aims to suppress active disease and prevent further disability by removing disease-causing cells and resetting the immune system. During the procedure, doctors collect a participant's blood-forming stem cells, give the participant high-dose chemotherapy to deplete the immune system, and return the participant's own stem cells to rebuild the immune system. The treatment carries some risks, and many participants experienced the expected side effects of HDIT/HCT, such as infections. Three participants died during the study; none of the deaths were related to the study treatment. Five years after HDIT/HCT, most trial participants remained in remission, and their MS had stabilized. In addition, some participants showed improvements, such as recovery of mobility or other physical capabilities.
Investigating the Details of Slowed Immune Aging via Calorie Restriction
The practice of calorie restriction slows all aspects of aging, and produces sweeping changes in the operation of cellular metabolism. This makes for a great deal of work in order to understand how and why it generates beneficial effects. Even separating out root causes from downstream consequences is a slow and expensive challenge for the research community, as understanding calorie restriction must proceed hand in hand with understanding the fine details of cellular biochemistry as a whole - an enormous project that is nowhere near complete. You might look back at the past decade of work on sirtuins for an example of one small slice of the bigger picture, still not complete, and so far undertaken at a cost of hundreds of millions. In the open access paper noted here, the focus is on one small part of the slowing of immune decline with aging as a result of calorie restriction. As is often the case, the research generates more questions than answers:
In mice, calorie restriction enhances responses to vaccination, reduces the incidence of spontaneous malignancies, and, in some inbred strains, extends lifespan. Specifically, restriction of the calorie intake of C57BL/6J mice by 40% compared to that of mice fed ad libitum (AL), extends median lifespan by more than 35% (i.e., from around 24 months to around 32 months) whereas the lifespan of DBA/2J mice is not extended by calorie restriction. This differential response to calorie restriction may be linked to lower basal metabolic rate, lower oxygen consumption, higher oxidative stress, higher body fat, and continued weight gain throughout adult life in C57BL/6 mice compared to DBA/2 mice fed ad libitum (AL) although differential effects on nutrient sensing cannot be ruled out.
Importantly, age-associated changes in the adaptive immune system - typified by thymic involution, reduced production of naïve T cells, reduced T cell proliferation, reduced cytotoxic T lymphocyte activity, and progressive skewing of the T cell pool toward more mature, memory phenotypes with increasing age - are attenuated by calorie restriction. In mice and in non-human primates, calorie restriction conserves T cell function and repertoire and promotes production and/or maintenance of naïve T cells. The effects of aging and calorie restriction on the innate immune system are, however, much less well studied. Altered function of innate cell lineages of aged individuals has been linked to defective immune regulation and chronic inflammation. In particular, age-associated dysfunction of natural killer (NK) cells has been reported in mice and humans. Progressive narrowing of the NK cell functional repertoire with increasing age may contribute to immune senescence.
NK cells in aged mice appear functionally impaired. Calorie restriction seems to mimic the effects of aging on murine NK cells, with 40% calorie restriction leading to reduced numbers of peripheral NK cells and decreased proportions of the most differentiated NK cell subset in 6-month-old C57BL/6 mice. One study also suggested that CR mice are more susceptible to infection, with lower NK cell activity, again mimicking the effects of aging, although the causal relationship between NK cell function and outcome of infection remains to be tested. Despite evidence that calorie-restriction appears to mimic the effects of aging in murine NK cells, calorie restriction enhances healthy life span in C57BL/6 mice suggesting that age-related changes in murine NK cells may have evolved to preserve innate immune function, and thus resilience in the face of infection, in adult life and thus that there is an underlying unappreciated interaction between age and calorie intake. In an attempt to reveal this interaction, we have - for the first time - analyzed the effects of calorie restriction on NK cell and T cell phenotype and function throughout the life course in C57BL/6J and DBA/2J mice.
To our surprise, the effect of calorie restriction on the NK cell population was to exaggerate, rather than attenuate, the normal age-associated changes in NK cell phenotype and function. Our data suggest that calorie restriction attenuates age-associated effects in T cells but, conversely, accelerates the effects of aging in NK cells, and that the effect of calorie restriction is much more marked in C57BL/6 mice than in DBA/2 mice. The conventional wisdom is that aging is associated with the accumulation of mature, terminally differentiated immune cells with restricted functional capacity, leading to loss of immune integrity, while calorie restriction is believed to preserve immune function, possibly by maintaining the pool of immune cell precursors or stem cells. However, very few studies have looked at the effect of aging or calorie restriction on NK cell function. Overall, calorie restriction had at least as big an effect as age on NK cell and T cell phenotype, and, where aging per se affected immune cells, these effects could be almost totally reversed (in the case of T cells) or were markedly exaggerated (in the case of NK cells) by calorie restriction. The very different effects of age and calorie restriction on T cell and NK cell differentiation and maturation suggest that, despite their many shared features, the underlying response of T cells and NK cells to increasing age and nutritional constraints is, mechanistically, very different.
Similarly, although the immunological effects of aging are very similar in C57BL/6 and DBA/2 mice, the effect of calorie restriction is much less obvious in DBA/2 mice than in C57BL/6 mice. This suggests, but does not prove, that the lack of benefit (in terms of longevity) from calorie restriction in DBA/2 mice may be associated in some way with the failure of the immune system to respond to the change in diet. As discussed above, an intriguing finding from this study is that calorie restriction potentiates age-associated changes in NK cell phenotype and function while simultaneously ameliorating age-associated changes in T cells. However, given the different age-related trajectories of T cell and NK cell populations in control animals, the overall effect of calorie restriction is to maintain larger populations of immature or less differentiated T cells and NK cells. Among NK cells, the maintenance of a less mature phenotype is reflected functionally with increased proliferative responses to cytokine stimulation. This is in partial agreement with evidence from mice and humans, which indicates that less differentiated NK cells express high levels of cytokine receptors and respond strongly to cytokine-mediated signals.
Overall, the effect of calorie restriction is that 22-month-old CR mice retain the immune cell phenotype of 6-month-old conventionally reared mice - the underlying basis for this is not entirely clear. Retention of an immature T cell and NK cell phenotypes in aged, CR mice may result from continuing production of new, immature cells; from accelerated turnover and apoptosis of mature cells; from extension of the life span of individual cells such that they take much longer to mature; or from a combination of any or all of these processes. Our data suggest that calorie restriction may preserve immune function in later life but this is only likely to be beneficial if improved immune function can be achieved whilst still maintaining the energy reserves required to fight infection. More research is required to better understand the interaction between nutritional status, immune function, and healthy aging, in relevant animal models and in humans.
An Interview with Irina and Michael Conboy on Blood Factors in Aging
Here is a lengthy interview with researchers Irina and Michael Conboy on their work with parabiosis. This involves joining the circulatory systems of an old and a young mouse, and studies have shown that this reverses some measures of aging in the old mouse. Researchers have so far largely focused on the possible effects of signal molecules present in young blood, but the most recent work from the Conboy lab provides fairly compelling evidence to suggest that the more interesting benefits are instead produced by a dilution of harmful signals in old blood. This is reinforced by the possible identification of one of those signals by another research group. In the bigger picture, this means that initiatives involving blood transfusions are probably going to fail, and would explain why transfusions in mice didn't produce noteworthy outcomes. One alternative approach suggested by this new research is plasmapheresis, a class of existing therapy in which blood plasma is replaced in volume, and which would hopefully also dilute harmful signals in the process.
Dan Pardi: In my conversation with Aubrey de Grey, he was optimistic of stem cells being one area in which we can effect aging itself. If we have these stem cells that regenerate and then can become new tissue, what does happen with aging to stem cells?
Irina Conboy: What we believe and we found is that, interestingly, stem cells remain relatively young in a person who is 80, 85 years old. You are like a mosaic of cells. Many of your cells are old, decrepit. They have damaged DNA and short telomeres and what not. But stem cells are actually pretty healthy, and young, and functional. They are inhibited. They are pretty much blocked by their surrounding tissue, called the niche. That niche blocks them from performing any work. The cells that we know work just like keep sleeping and do not repair the tissue. Then, because of that, when there is tissue damage and stem cells are sleeping, they are not activated. Then the damage is not regenerated. Instead you have fibrosis. It's like your plan B. You now make fibrous tissue, and depose fat tissue to replace the damage. Then gradually the time, you just turn into this big scar and big fat blob. Then if you figure that there are proved ways to reawaken stem cells then 70 year old, 80 year old person will start regenerating. All of the organs as if they are 20 year old. Gradually, not only you prevent all these bad diseases to happen but perhaps start getting even younger.
Dan Pardi: One publication that got a lot of attention is one where you did this parabiosis experiment where you had blood exchanged from an old rat to a young rat. Tell us a little bit about that one.
Irina Conboy: In this experiment we found that old animal becomes much younger, with respect to muscle degeneration, formation of new neurons in the brain. Also, liver regeneration. All of these molecules which were responsible for making animal younger were also rejuvenated. It was not just a fluke. There was also fundamental mechanism of how they became younger. The young animals suffered from this connection. Became older, particularly in liver and in brain. From that time on, people kind of became obsessed with the stories about vampires and that young blood holds the secret to health, and youth, and so forth. It was really strange to me. It was surprising that that was such a simplistic interpretation of our findings. Which we did not intend our findings to be interpreted like that. Also, that how much, I guess, interest it got. It really absorbed all of the funding in the area. As a result there was not enough funding to do any alternative work, which in my opinion was the most important work to do. The main secret there is that mice share more than blood when you staple them. When they live together for like an entire month, then old mouse now has access to young heart. The blood pressure becomes better. Young lungs, so now you have better oxygenation of blood. Red blood cells now are more oxygenated. Also, you have young red blood cells going into an old animal. Also, you have young liver. You have much better metabolism. You have young immune system. You have much less inflammation. It is not, you know, those secret proteins in blood. It is simple things like how much oxygen does your brain get. That was completely overlooked.
Dan Pardi: What did you think was going on? What was your next experiment that took it a step further to identify really what was going on?
Michael Conboy: At the time we also would take cells and grow them in culture. Usually when you do that you add some amount of serum to that. That's the liquid fraction of blood. You spin out the cells. If you grow the cells in young serum, they grow very well. If you grow them in old serum, they grow poorly. What was interesting was if we mixed young serum and old serum together, the cells grew poorly. That indicated that there was something that was in the old serum that was suppressing the growth and was also dominate over whatever was in young serum. That got us thinking that what was growing on in parabiosis must be more along on the lines of the young animals filtering some old, inhibitory stuff out of the old mouse. Maybe more than it's adding young positive factors to the mix. That got Irina thinking that there's got to be something that circulates, that's inhibitory, and what could it be?
Irina Conboy: Then, we were thinking about the clear experiment. A proof of principal which we will once and for all discriminate between whether young blood is good or whether we need to remove old blood inhibitors. That's how we switched to the blood exchange. Which is much more difficult to set up than parabiosis. It is much better experimental set up to answer many questions. In blood exchange, in fact, we do exchange only blood. There are small catheters which are inserted into mouse veins. You can imagine, mice are very little, how tiny their veins are. You need to be very, very skilled to be able to catheterize mouse veins. Then there is a pump that pretty much mixes the blood from young mouse with an old mouse to equilibrium. Which is identical to parabiosis. There is no loss of blood. There is no gain of blood. They are mixed in exactly the same way. That happens in one day. Then mice are not living together for one month anymore. They do not share organs. You exchange their blood. Then very quickly you can study what happens with their organs and tissues. Most surprising findings that you have from this experiment is that, yes, blood exchange without any organ sharing or adaptation does have effect on youth and aging. The effect is almost instantaneous. It implies completely different set of mechanisms as compared to when mice are sutured and running together.
Dan Pardi: For humans would be like a dialysis situation. Now you have to just figure out, how frequently? How much needs to be removed and put back in?
Irina Conboy: We have clinical trials under development with our colleague Professor Dobri Kiprov from San Francisco Blood Apheresis Clinic. Who is doing blood exchange in people for 35 years. He contacted us because of reading our papers. Make him interested in can this be repositioned. Repositioning is when you already have FDA approved procedure and your clinical trial therefore are much more advanced. You just see if the same or slightly modified protocol can be used. We do plan to study in those clinical trials how much younger do people become? Do they become younger in their epigenetics for example? Do they become younger in their lack of predisposition to cancer? There are many, many parameters that we can study. How much improvement can we expect from our process or approach where we take person's blood and it goes through the plasmapheresis machine in the approved process?
Short Term Damage Done by Amyloid in the Brain Appears to be Reversible
This compact study suggests that the damage caused to neurons by the presence of β-amyloid in the short term can largely repair itself if the amyloid is removed. This is one of a number of lines of evidence to indicate that targeted clearance of amyloid should produce reversal of symptoms in Alzheimer's disease in at least the earlier stages, before there is widespread cell death, rather than just a halt to the progression of the condition.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized clinically by memory loss and cognitive decline. Its major pathological hallmarks are extracellular senile plaques and intracellular neurofibrillary tangles, which are composed of amyloid β-protein (Aβ) and phosphorylated tau (p-tau) protein, respectively. A central role of Aβ in the molecular pathology of AD has been established. Aβ is generated by sequential cleavages of amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE1) and γ-secretase. Under pathological conditions, Aβ self-aggregates to form Aβ oligomers, which likely induce abnormalities of tau and cause cellular stress responses, including caspase activation and disturbances of synaptic structure and plasticity. Thus, Aβ oligomers are considered to be an initiator of AD pathology.
The mechanisms by which Aβ oligomers induce neurotoxicity, critical issues from a therapeutic standpoint, remain to be elucidated, although several hypotheses have been suggested. The major theory is that extracellular Aβ oligomers interact with certain cell surface receptors to cause aberrant signal transduction. Alternatively, it has been suggested that extracellular Aβ oligomers disrupt the cell membrane directly or intracellular Aβ oligomers elicit neurotoxicity. Although a link between Aβ oligomers and tau has been established, signaling pathways linking the two remain elusive. It also remains to be clarified whether the neurotoxicity of Aβ oligomers is reversible and abates upon their removal. We previously established a primary neuron culture model in which Aβ oligomers trigger apparent neurotoxicity with relatively modest neuronal death. In the current study, we took advantage of this system to investigate the reversibility of Aβ oligomers-associated neurotoxicity, characterized by caspase activation and tau abnormalities. Here, we present evidence that the neurotoxicity of Aβ oligomers is reversible in primary neurons.
Our data showed that Aβ-O induces activation of caspase-3 and eIF2α, and abnormal phosphorylation and cleavage of tau. These abnormal alternations have been reported to be present in AD brains, suggesting that our model reflects the characteristic features of AD pathology. Our study also provides evidence of a direct link between Aβ oligomers and tau abnormalities, in accord with previous studies. To evaluate whether Aβ oligomer neurotoxicity is a reversible or irreversible process, we used an experimental paradigm in which neurons exposed to Aβ oligomers for 2 days were further treated with Aβ oligomers for 2 additional days or were deprived of Aβ oligomers for this same culture period. We then compared control and Aβ-oligomer-treated neurons on day 2, and control, Aβ-oligomer-treated and Aβ-oligomer-deprived neurons on day 4. We first focused on caspase-3 and eIF2α, both of which are thought to be important in mediating AD neurodegenerative processes. We found that the levels of cleaved caspase-3 and p-eIF2α in Aβ-oligomer-deprived neurons were much lower on day 4 than those in neurons continuously treated with Aβ oligomers, and were similar to those in controls. These findings suggest that neurons can recover following Aβ oligomer removal, even after neuronal injury responses to Aβ oligomers have already progressed, supporting the view that treatments targeting Aβ oligomers have significant therapeutic potential for AD.