Mitochondria are important in aging, and this appears to be related to the generation of oxidative molecules that takes place as a side-effect of the creation of chemical energy stores. A fair number of the ways to modestly slow aging in short-lived species change the operation of mitochondria so as to also change the output of oxidants. These reactive molecules can disrupt cellular machinery, but also act as signals, so it is still far from clear as to which are the most important secondary consequences in the various contexts of interest. In the longer term, it is plausible that these oxidants are causing DNA damage in the mitochondria themselves, something that has the potential to spiral out of control to lead to dysfunctional mitochondria, a dysfunctional cell, and damage that can spread out into surrounding tissues. One potential way to suppress the output of oxidative molecules is genetic engineering to increase levels of natural antioxidant compounds localized to the mitochondria, and one of the earliest attempts to do this targeted mitochondrial catalase in laboratory mice. This has produced varied outcomes, however, ranging from little effect to slowed aging. The paper noted here might go some way towards explaining why research groups have seen mixed results from this approach, as the age of the mice used in these studies appears to be a crucial factor:

Reactive oxygen species (ROS) are associated with the progression of a broad spectrum of pathologies including aging. Mechanistically, this has largely been attributed to oxidative modification of cellular macromolecules, including lipids and proteins. While ROS have been widely regarded as a major component of aging since the 'free radical theory of aging' was proposed in the 1950s, there is an increasing appreciation that ROS also serve important physiological signaling roles. It is therefore important to closely examine both negative and positive consequences of therapeutic interventions that target ROS. Given that oxidative modifications can impair the activity of macromolecules, and the well-documented correlation between oxidative damage and aging reported in almost all models studied, it has been tempting to conclude that this is a likely mechanism for aging. However, there are many observations at odds with this theory of aging. Clinical trials of dietary antioxidants have thus far shown little to no efficacy. Some have shown adverse outcomes. In mice, deletion of many antioxidant enzymes has little effect on lifespan and, importantly, overexpression of several antioxidants including superoxide dismutase and peroxisomal catalase has failed to extend lifespan.

Our group has previously shown that mice overexpressing mitochondrial-targeted catalase (mCAT), but not nuclear or peroxisomal catalase, have an approximately 20% increased median and maximal lifespan, suggesting that reducing ROS specifically in the mitochondria is key to achieving a beneficial effect on aging. mCAT has been shown to reduce oxidative modification of DNA and proteins and delays the progression of multiple pathologies. We have also demonstrated that mCAT is protective against cardiac aging. However, it has been increasingly recognized that ROS has beneficial roles in signaling, hormesis, stress response, and immunity. We therefore hypothesized that mCAT might be beneficial only when ROS approaches pathological levels in older age and might not be advantageous at a younger age when basal ROS is low. We analyzed abundance and turnover of the global proteome in hearts and livers of young (4 month) and old (20 month) mCAT and wild-type (WT) mice. In old hearts and livers of WT mice, protein half-lives were reduced compared to young, while in mCAT mice the reverse was observed; the longest half-lives were seen in old mCAT mice and the shortest in young mCAT. Protein abundance of old mCAT hearts recapitulated a more youthful proteomic expression profile. However, young mCAT mice partially phenocopied the older wild-type proteome. Age strongly interacts with mCAT, consistent with antagonistic pleiotropy in the reverse of the typical direction. These findings underscore the contrasting roles of ROS in young vs. old mice and indicate the need for better understanding of the interaction between dose and age in assessing the efficacy of therapeutic interventions in aging, including mitochondrial antioxidants.

Link: http://onlinelibrary.wiley.com/doi/10.1111/acel.12472/full

Calorie restriction is demonstrated to slow the progression of neurodegenerative disease in numerous species, but picking out specific relevant mechanisms from the sweeping changes in cellular behavior that occur as a result of a lower calorie intake has proven to be a challenge. The scientists involved in the research noted here focus on just one, relating to dysfunction of calcium metabolism in neurons. As might be imagined, this is the tiniest slice of the complete picture of calorie restriction and health, considered at the cellular level. A full accounting of exactly how calorie restriction works to improve health and delay aging remains to be created. It is a job of staggering size, one that must proceed in parallel with the equally large task of producing a comprehensive map of metabolism and how it changes with age. It seems plausible that researchers will still be working on this well after the first suite of rejuvenation therapies after the SENS vision are a going concern. It is fortunate that the faster and more effective approach to treating aging described in the SENS proposals exists: if it didn't, our prospects for longer, healthier lives would be far worse.

Studies of different animal species suggest a link between eating less and living longer, but the molecular mechanisms by which caloric restriction affords protection against disease and extends longevity are not well understood. The results of new in vitro and in vivo experiments include the finding that a 40% reduction in dietary caloric intake increases mitochondrial calcium retention in situations where intracellular calcium levels are pathologically high. In the brain, this can help avoid the death of neurons that is associated with Alzheimer's disease, Parkinson's disease, epilepsy and stroke, among other neurodegenerative conditions. Calcium participates in the process of communication between neurons. However, Alzheimer's disease and other neurological disorders can cause an excessive influx of calcium ions into brain cells due to overactivation of neuronal glutamate receptors. This condition, known as excitotoxicity, can damage and even kill neurons.

To verify the effect of caloric restriction on excitotoxicity, scientists compared two groups of mice and rats. The control animals were given food and water ad libitum for 14 weeks and were overweight at the end of the experiment. The other group received a 40% caloric restriction (CR) diet for the same period. In the first test, the animals were injected with kainic acid, a glutamate analogue with a similar effect in terms of inducing neuronal calcium influx, albeit more persistent. In rodents, it can cause brain damage, seizures and neuronal cell death due to overactivation of glutamate receptors in the hippocampus. It is used in the laboratory to mimic epilepsy. "We administered a small dose to avoid killing the animal. Even so, kainic acid caused seizures in the control group. It had no effect on the CR group."

The next step was to see what happened when the mitochondria isolated from each group were treated with cyclosporin, a drug known to increase calcium retention. While calcium uptake did indeed increase in the mitochondria from the control group, it remained unchanged in the CR group, eliminating the difference observed in the previous test. "Cyclosporin's target in mitochondria is well known. The drug inhibits the action of a protein called cyclophilin D, leading to increased mitochondrial calcium retention." In this case, however, cyclophilin D levels were found to be the same in both groups. The researchers therefore decided to measure the levels of other proteins that might be interfering with cyclophilin D's action in the organism. "We discovered that caloric restriction induces an increase in levels of a protein called SIRT3, which is capable of modifying the structure of cyclophilin D. It removes an acetyl group from the molecule in a process known as deacetylation, and this inhibits cyclophilin D, so that the mitochondria retain more calcium and become insensitive to cyclosporin." Just as other research groups had already found, the team also observed an increase in the activity of antioxidant enzymes such as glutathione peroxidase, glutathione reductase and superoxide dismutase in the CR rodents' mitochondria. These results suggest an enhanced capacity to manage cerebral oxidative stress, a condition that contributes to the onset of several degenerative diseases.

Link: https://www.eurekalert.org/pub_releases/2016-10/fda-crc101916.php

Today I thought I'd share a recent commentary on cellular senescence research to treat aging. A growing amount of work is taking place on the fundamentals of clearing senescent cells as a method of partial rejuvenation. The presence of newly founded companies pushing forward towards clinical translation, and results showing life extension and improved tissue function in normal mice are drawing more funding into the field. Folk in our grassroots community are also helping where they can, such as by crowdfunding the first studies to be carried out by the Major Mouse Testing Program earlier this year, or providing seed funding for promising companies. All of this effort is not before time: it is nearing fifteen years since SENS rejuvenation biotechnology advocates first gathered the evidence supporting senescent cell accumulation as a fundamental cause of aging, and began calling for more research on this topic. Various research groups are now focusing on different methods of clearance and their effects on specific tissues and organs, seeking to prove or disprove effects on degenerative aging. We should expect to see a mix of benefits and absence of benefits once the dust settles: senescent cells are only one of the seven broad classes of age-related damage enumerated in the SENS research proposals. Their presence may contribute to many or even all of the common age-related conditions, but they are not significant causes of all of the specific forms of secondary and later cell and tissue dysfunction in the aging body.

To pick one example, earlier this year researchers published a study of the effects of reduced senescent cell counts on aspects of vascular aging. It was indeed a mix of benefits and absence of effects: fewer senescent cells led to reduced calcification of blood vessel walls, associated with blood vessel stiffening with age, but it didn't have much of an impact on the development of atherosclerotic plaques. Both of these items are about as serious in their consequences over the long run. Stiffening of blood vessels drives hypertension, which in turn produces damage to delicate tissues such as the brain and kidneys as tiny blood vessels suffer structural failure at a greater rate. It also provokes remodeling of heart tissue, leading to heart failure, and along the way helps to turn atherosclerosis into a fatal condition. The fatty, inflamed plaques that distort blood vessels eventually grow to the point of rupture, which either blocks or breaks important large vessels. That is a frequently fatal occurrence. This mixed outcome was an interesting result, as one of the characteristics of senescent cells is that they produce greater levels of chronic inflammation via the mix of signals they generate, the senescence-associated secretory phenotype. This signaling is how small numbers of senescent cells, perhaps 1% of the cells present in an organ, can distort the function of the other 99%. Inflammation is pretty important to the pace of progression of atherosclerosis, so one might expect a reduction in the number of senescent cells to slow the pace of that condition - but apparently not in this particular scenario.

The recently published commentary linked below is a celebration of the fact that the scientific community has finally achieved some traction in the matter of a treatment for the root causes of aging, one likely to produce reliable, if partial, degrees of rejuvenation. It is not unreasonable at this point to expect senescent cell clearance to achieve larger and more robust results on aging and age-related disease than much of the rest of present day medicine, and to do so in a way that is additive to other methodologies. That capability will emerge fairly soon in clinics, a few years to a decade from now, varying with the regulatory environment and where the products are offered. This is the true benefit of focusing on reverting the fundamental damage that is the cause of aging, rather than tinkering with later stages of disease and malfunction.

Senescent cell death brings hopes to life

Life expectancy in the developed countries is continuously increasing. However, age-related diseases lead to late life complications and remain the most prevalent cause of mortality. One of the cellular components that is present in sites of age-related pathologies and accumulates during aging is senescent cells. These cells are formed when a stress signal triggers terminal cell cycle arrest in proliferating cells. Entrance to a state of senescence deprives damaged cells of their proliferative potential and thus limits tumorigenesis and tissue damage. Despite the protective role of cellular senescence, the long term presence of senescent cells is harmful to their environment. These cells secrete a plethora of pro-inflammatory factors that might aid their removal by the immune system. However, at advanced age senescent cells gradually accumulate in tissues and the secretory phenotype promotes a chronic "sterile" inflammation which is a hallmark of unhealthy aging. Elimination of senescent cells in mice by a genetic approach led to a decreased burden of age-related disorders, and an increased median survival of the mice. Therefore, pharmacological elimination of senescent cells in-vivo is a promising strategy for treatment of age-related diseases associated with accumulation of senescent cells. An attractive method to implement this strategy would be to induce apoptosis preferentially in senescent cells. The scientific basis of this approach relies on an understanding of the molecular mechanisms that distinguish the regulation of apoptosis in senescent cells from other cells.

Resistance of senescent cells to both extrinsic and intrinsic pro-apoptotic stimuli testifies for complex regulation of apoptosis in these cells. We recently demonstrated that senescent cells, induced to senesce by different kind of insults, upregulate proteins of the anti-apoptotic BCL-2 family. Combined knockdown of these proteins or their inhibition by a small molecule inhibitor, ABT-737, selectively skew cell-fate decision in senescent epithelial cells in-vivo toward apoptosis. Therefore, the expression of BCL-2 family members endowed senescent cells with resistance to apoptosis. The senolytic activity of the ABT-737 molecule was demonstrated in in-vivo models of senescence. DNA damage-induced senescent cells were formed in the lungs upon ionizing irradiation of mice. Administration of ABT-737 rapidly reduced the number of senescent cells, concomitantly with an increase in apoptosis.

Alongside with the BCL-2 family inhibitors, other approaches for selective elimination of senescent cells, also termed senolytic approaches, have been identified. For example, the combination of 2 drugs, dasatinib and quercetin, was shown to exert killing potential of senescent preadipocyte and endothelial cells. Elimination of senescent cells could also be achieved by adapting tools from the field of cancer therapy. One such possibility is utilization of common immunotherapy practices following identification of senescence-specific markers. The immune system is a natural resource that is able to recognize and eliminate senescent cells. Using its properties in combination with immunotherapy approaches or with emerging senolytic drugs might lead to more specific and efficient elimination of senescent cells. However, no matter what would be the approach of choice, it is necessary to keep in mind that senescent cells participate in variety of essential physiological functions such as in wound healing, tumor suppression, regulation of glucose levels and embryonic development. In order to develop efficient senolytic approaches it is necessary to dissect beneficial and detrimental functions of senescent cells in different physiological and pathophysiological conditions using in-vivo models.

Successful development of senolytic drugs will bring senescent cells to the forefront of anti-aging therapies. However, it is necessary to understand the effect of elimination of senescent cells on diverse cell communications in the complex tissues. Elimination of senescent cells by ABT-737 or ABT-263 was followed by increased proliferation of stem cells in both skin and haematopoietic system. These results suggest that senolytics can have an impact on tissue regeneration and can potentially be used in regenerative medicine. This approach will combine elimination of damaged cells with stimulation of proliferation of healthy progenitors, in a way that could restore tissue fitness in diseases associated with reduced tissue function. In summary, senolytic drugs can become a future regenerative medicine. Treatment with senolytic drugs results in the elimination of senescent cells, thus blocking tissue degeneration and late life complications. In turn, elimination of senescent cells leads to the proliferation of stem cells, allowing tissue regeneration. This joined effect of senolytic drugs will restore tissue fitness and will help restraining age-related pathologies.

There has been a fair amount of news regarding the SkQ class of mitochondrially targeted antioxidant this past year, most likely because clinical development in Europe is moving ahead. Having one or more for-profit entities involved, even when they are fairly young companies, tends to bring more funding into ongoing research, both directly and indirectly. This type of antioxidant, unlike the antioxidant supplements you can buy in a store, has been shown to modestly slow aging in short-lived laboratory species. It is theorized that additional antioxidants localized to mitochondria soak up some of the oxidants produced by the mitochondria before those molecules can damage mitochondrial DNA. Alternatively, it is possible that the more important mechanism is that a reduction in the flux of oxidants at that point leads to other beneficial changes in cell metabolism, as mitochondrial oxidants are a signaling mechanism as well as a source of damage. Certainly many of the methods shown to slow aging in the laboratory involve altered mitochondrial function, especially insofar as it relates to the rate at which oxidant molecules are generated. The effects of mitochondrially targeted antioxidants on inflammation have proven to be larger and more easily measured, however, which is why present clinical development is focused on inflammatory eye conditions. Still, a steady flow of studies like the following are emerging to show benefits in a range of animal models for various age-related conditions:

Alzheimer's disease (AD) is a progressive, age-dependent neurodegenerative disorder featuring progressive impairments in memory and cognition and ultimately leads to death. According to the most widely accepted theory, the "amyloid cascade" hypothesis, AD arises when amyloid precursor protein (APP) is processed into amyloid-β, which accumulates in plaques. There is growing evidence that mitochondrial damage and oxidative stress lead to activation of the amyloid-β cascade and, accordingly, the mitochondrial dysfunction is a significant contributing factor of the onset and progression of AD. According to the "mitochondrial cascade hypothesis" amyloid-β is a marker of brain aging, and not a singular cause of AD. Many studies have confirmed that mitochondrial dysfunction is likely to be the leading cause of synaptic loss and neuronal death by apoptosis, representing the most likely mechanism underlying cortical shrinkage, especially in brain regions involved in learning and memory, such as the hippocampus. The mitochondrial changes increase amyloid-β production and cause its accumulation, which in turn can directly exert toxic action on mitochondria, thus aggravating the neurodegenerative processes.

Here, using OXYS rats that simulate key characteristics of sporadic AD, we set out to determine the role of mitochondria in the pathophysiology of this disorder. OXYS rats were treated with a mitochondria-targeted antioxidant SkQ1 from age 12 to 18 months, that is, during active progression of AD-like pathology in these animals. Dietary supplementation with SkQ1 caused this compound to accumulate in various brain regions, and it was localized mostly to neuronal mitochondria. Via improvement of structural and functional state of mitochondria, treatment with SkQ1 alleviated the structural neurodegenerative alterations, prevented the neuronal loss and synaptic damage, increased the levels of synaptic proteins, enhanced neurotrophic supply, and decreased amyloid-β protein levels and tau hyperphosphorylation in the hippocampus of OXYS rats, resulting in improvement of the learning ability and memory. Collectively, these data support that mitochondrial dysfunction may play a key role in the pathophysiology of AD and that therapies with target mitochondria are potent to normalize a wide range of cellular signaling processes and therefore slow the progression of AD.

Link: http://dx.doi.org/10.18632/aging.101054

Improved control over plaque and unwanted bacteria in the mouth could improve long-term health. There is a demonstrated link between dental plaque, consequent gum disease, and whole-body inflammation. Higher levels of inflammation raise the risk of suffering heart disease and other conditions: chronic inflammation speeds the development and progression of all of the common age-related diseases. Thus any large improvement in everyday dental technology should also slightly slow the pace of degenerative aging via a reduction in inflammation. The results reported here are a very modest example of this type of progress, nothing to get too excited about: it is more in the way of a suggested change in the culture and methodology of brushing teeth. The researchers take an approach used by dentists, staining plaque to make it easier to remove, and package it for everyday use. Nonetheless, even something as simple as that can make some difference to inflammation. Consider this as a reminder to pay attention to the march of technology in this field, as the outcomes are relevant to much more than the health of teeth.

For decades, research has suggested a link between oral health and inflammatory diseases affecting the entire body - in particular, heart attacks and strokes. The results released today from a randomized trial of a novel plaque identifying toothpaste, show statistically significant reductions in dental plaque and inflammation throughout the body. Inflammation throughout the body is accurately measured by high sensitivity C-reactive protein (hs-CRP), a sensitive marker for future heart attacks and strokes. In this trial, all randomized subjects were given the same brushing protocol and received a 60-day supply of toothpaste containing either the plaque-identifying toothpaste or an identical non-plaque identifying placebo toothpaste. To assess dental plaque, all subjects utilized a fluorescein mouth rinse, and intraoral photographs were taken under black light imaging. For hs-CRP, levels were measured by an independent laboratory using an enzyme linked immunosorbent assay.

"While the findings on reducing dental plaque extend a previous observation, the findings on decreasing inflammation are new and novel." This is the first toothpaste that reveals plaque so that it can be removed with directed brushing. In addition, the product contains unique combinations and concentrations of cleaning agents that weaken the core of the plaque structure to help the subject visualize and more effectively remove the plaque. Based on these findings, researchers are drafting an investigator initiated research grant proposal to the National Institutes of Health (NIH). This large scale randomized trial will test whether the toothpaste reduces risks of heart attacks and strokes.

Link: https://www.eurekalert.org/pub_releases/2016-10/fau-tsr101416.php

At some point in the foreseeable future, it will become possible to grow functional replacement organs and large tissue patches from a patient skin sample in bioreactors. This capability will replace the present insufficient and unreliable donor sources of organs for transplantation. The cost and logistics will be much less onerous, especially if tissue engineering is paired with reversible vitrification, allowing replacement organs to be generated and then kept in storage until needed. Given the present state of tissue engineering, in which an increasing number of functional tissues can be generated in small sizes, and the trajectory of regenerative medicine as a whole, it seems inevitable that these capacities will come to pass. Whether or not they are widely used is an economic question, a race yet to be run between organ engineering for transplantation on the one hand and in situ repair and rejuvenation of existing organs on the other. Some combination of cell therapies and first generation SENS rejuvenation treatments to clear out metabolic waste, senescent cells, and the like could well prove a better choice for patients than undergoing the major surgery of transplantation, even if the transplanted organ is of a higher quality than the repaired aged organ.

There is a way to go yet before organs can be reliably grown from cells in bioreactors, however. Yet on the way to that goal, there are a number of potential shortcuts and transitional technologies that might be (a) be realized more rapidly, (b) allow the creation of useful organs for transplantation, and (c) provide a more reliable and less expensive option than the present system of organ donation. For example, the use of decellularization may provide incremental gains in the number of organs available, and reduce some of the hazards of transplantation. Decellularization involves taking a donor organ, which might include one that wouldn't make the cut for present day transplantation due to cell damage, stripping all of its cells, and then repopulating the organ using a mix of the patient's own cells. This has been accomplished in the laboratory, and perhaps the most interesting implication of this line of research is that the organ need not be human. Pigs have organs of about the right size, for example, and genetic engineering to remove the known problem proteins that might remain in a decellularized porcine organ is a project of feasible scope. Hard, but not impossible. There are research groups working towards this goal today, some already in the commercial stage of development.

Humanized organs in gene-edited animals

Treatment of chronic diseases has resulted in the successful use of cell therapy for the treatment of hematopoietic diseases and cancers as well as device therapies for the treatment of heart disease, diabetes and osteoarthritis. These therapies, while effective, have not been broadly applied to end-stage disease. Currently, curative therapies for advanced end-stage organ failure require transplantation, which is limited by donor organ availability. While millions of patients could benefit from such therapy, the scarcity of organs severely limits the number of transplantations that are performed. This disparity has fueled intense interest focused on alternative organ sourcing and regenerative medicine.

The use of human cells or lineages in a nonhuman animal has been extensively pursued in biomedical research. For example, the incorporation of human hematopoietic stem cells into early, preimmune fetal lamb embryos was demonstrated in the 1990s. These investigators observed significant, long-term, multilineage engraftment of these cells in sheep bone marrow and blood. Additionally, in 2005, functional human neurons in the mouse were developed by injecting human embryonic stem cells into the ventricles of mice. Humanized liver models in mouse have been well established and are currently used for the study of pharmacokinetics and toxicity. In 2001, the repopulation of a mouse liver with human hepatocytes was described. In 2004, human hepatocytes were transplanted into an immunodeficient mouse model to generate chimeric mice with an 80-90% humanized liver. The utility of these chimeric mice in studying human toxicity and dosing and disease is well recognized. More recently, 3D vascularized and functional human livers have been generated by transplanting human liver buds, developed in vitro, into mice. Various studies have demonstrated the capacity for targeted organ chimeras using blastocyst-complementation strategies. For example, a rat pancreas was produced in a mouse by the process of blastocyst complementation. In these studies, blastocysts mutant for Pdx1, the master regulatory gene for pancreatic development, were injected with pluripotent stem cells from wildtype rats. Transfer of the pluripotent stem cells from wildtype rats injected blastocysts and, subsequently, into surrogate mouse dams gave rise to mouse chimeras with functional pancreata composed of rat cells. These studies emphasized the importance of generating blastocysts, deficient for a key developmental regulatory factor, in which the embryo completely lacks the target organ. The blastocyst-complementation strategy has also produced organs such as the kidney and liver in rodents, and recently, the pancreas in pigs. The results of this latter study are significant, because it supports the notion of generating human patient-specific organs in pigs that can be subsequently used for transplantation or advanced therapies.

Groundbreaking scientific advances are bringing the scientific field closer to the reality of developing human organs in nonhuman animals. First, the advances in developmental biology have identified master regulators that are both necessary and sufficient to specify stem cells and direct them to differentiate to distinct lineages. Second, the ability to reprogram human somatic cells to a pluripotent stem cell state, human induced pluripotent stem cells (hiPSCs), has revolutionized the field of regenerative science and medicine. Third, genome-editing technologies, such as clustered regularly interspaced short palindromic repeat, allow for site-specific genome editing. Fourth, the ability to successfully perform somatic cell nuclear-transfer technology (i.e., cloning) in large animals has allowed for the genetic engineering of large animal models. The intersection and combination of these four emerging technologies makes feasible the ability to delete the genes that govern tissue or organ development in a host, thereby establishing a niche for humanized cells. In addition, the use of complementation experiments, where hiPSCs are transferred to a mutant blastocyst, followed by the transfer into a pseudopregnant host, could result in the potential rescue of the host phenotype rescue with a humanized organ. Therefore, it may be possible to engineer personalized organs in large animals and/or engineer unique human disease models in a large animal for preclinical testing of potential therapeutic agents.

Thus farming may well turn out to be one noteworthy component of the organ engineering industry that will arise over the next few decades: harvesting organs from animals, probably genetically engineered lineages specifically created for this purpose. With sufficiently advanced genetic engineering and use of implanted organ seeds or other strategies, the organs being grown in these animals could be completely human. Growing the organ of one species in an individual of another is also something that has been achieved in the laboratory. If you, like most people, happen to be comfortable with the ethics of eating meat, you should probably also be comfortable with farming organs for medical use.

For my part I think that there is a lot to be said for not undertaking the mass generation and killing of entities capable of suffering purely for one's own convenience, but given that I support the necessity of laboratory animals in medical research, my objection is clearly more utilitarian than absolutist. At the present time relinquishing the use of laboratory animals in the medical sciences would be worse than continuing use. In any case, in comparison to farming for food, organ farming and other research community use of animals is a drop in the ocean. Still, to my eyes both farming and laboratory studies of living beings are things that we should use technology to do away with - to cease these activities as soon as possible. This is as much a part of the goals of the Hedonistic Imperative as is eliminating suffering in humans. To end the farming of animals is in fact already possible, and could be accomplished given the will to do so. On the other side of the house, progress in computation and simulation will eventually enable the retirement of mice, flies, worms, and other species that researchers use in their studies. So all in all, it would be pleasant should the future include less farming of animals for organs and more generation of organs in bioreactors, but it is hard to predict how these things will pan out in advance. It all depends on the twists and turns of the economics of clinical application.

In the context of ongoing work on the beneficial effects of young ovaries in old mice, it is interesting to note that researchers have now managed to engineer functional mouse ovary tissue that produces eggs. The starting point was a cell sample, converted into induced pluripotent stem cells. It is a good example of the current state of the art in tissue engineering, in which many types of correctly functioning organ tissue can be produced in small amounts given just a small patient tissue sample to work with. Each tissue and organ requires its own recipe of signals and environment, and the discovery of working approaches is a slow grind, but once a methodology is established then the door is open for that particular tissue type.

Scientists have for this first time reprogrammed murine embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) into fully functional oocytes in the laboratory. In mice, oocytes are derived from primordial germ cells (PGCs), which form around day 6.5 of embryonic development. In female embryos, the PGCs make their way to what will turn into the ovary and enter meiosis to form primary oocytes, which begin to mature following puberty. Previously, researchers reported the ability to differentiate murine ESCs and iPSCs into PGC-like cells - a process that takes about five days in vivo - that could then develop into oocytes when transplanted into adult mice. The researchers also showed that mouse-derived PGCs can be used to produce fertile oocytes in the lab.

In the present study, researchers have now extended their culturing technique to encompass the entire embryonic stem cell to oocyte differentiation, which takes about 30 days in vivo. Starting with either stem cell type, the researchers first created the PGC-like cells by inducing expression of several genes and then mixed these cells with female gonadal somatic cells - which support germ cell development - to create "reconstituted ovaries" in vitro. The cells gradually lost expression of PGC markers and began to express oocyte markers. By three weeks of growth in culture, the team observed primary oocytes in meiosis prophase I within structures that resembled secondary follicles. One of the key components at this stage was the need to add an estrogen inhibitor to get the early stage oocytes to build ovarian follicles in vitro. The researchers then added follicle-stimulating hormone and two other factors to the medium and separated each follicle-like structure - inside which oocytes continued to grow for 11 more days - resembling full-size germinal vesicle oocytes. In the third phase, the germinal vesicle oocytes were cultured for one day in maturation culture medium to become meiosis II-arrested oocytes. "The stumbling block for a long time that this research group finally managed to overcome is coordination of the female germ cell development with its somatic environment at every step along the way"

Altogether, the team conducted three separate culture experiments that produced 58 reconstituted ovaries and 3,198 germinal vesicle oocytes, of which 28.9 percent matured to the meiosis II stage. Testing the quality of the meiosis II-arrested oocytes, the team found that about 78 percent had the correct number of chromosomes. Then, using RNA-sequencing on pooled oocytes, the researchers observed expression in the culture-derived oocytes comparable to that of meiosis II oocytes derived from in vivo adult and newborn pup ovaries. There were 424 genes that were either up- or downregulated compared to in vivo-derived meiosis II oocytes, particularly, mitochondrial function genes. To test whether the lab-cultured meiosis II oocytes were fully functional, the team fertilized the oocytes with wild-type sperm in vitro, and implanted the embryos into surrogate females, which resulted in healthy pups that were slightly heavier compared to wild-type pups but that developed normally and were fertile at 11 months.

Link: http://www.the-scientist.com/?articles.view/articleNo/47256/title/From-Stem-Cell-to-Oocyte-In-a-Dish/

Researchers here identify a protein that increases regeneration in the central nervous system following injury, or to restore lost plasticity and ability to adapt in later life. Spurring greater regrowth of damaged nerves is of great interest to the research community, and a range of approaches are underway at various stages of development. Despite promising results in animal studies so far the practical outcomes for human medicine are all fairly marginal, however. This will change in the years ahead, but at this point it is hard to say just where or when, or which of the avenues will prove to be the first one that works well enough to follow through to widespread clinical availability.

Neuronal plasticity and structural remodelling are fundamental feature of the developing nervous system and plays also an essential role during learning and injury-dependent remodelling and regeneration. In development, axons extend over long distances and form contacts with their target structure and facilitate functional connections. These neuronal connections become stabilized and restricted during maturation and secure proper functioning of the brain. Conversely, sprouting and regeneration is limited after decline of intrinsic axonal remodelling activity in aging brain and in an microenvironment rich in neurite growth inhibitors after neurological injury.

Several extracellular ligands account for the neurite growth inhibitory environment after maturation and injury. These ligands converge on the RhoA-Rho kinase pathway mediating the final signal transduction for neurite retraction and axon growth inhibition. Pharmacological and genetic interfering with the ligands Nogo/NgR or LPA promotes axonal regeneration and functional recovery after central nervous system injury. An essential step during development and regeneration is the initiation of actin-rich membrane protrusions termed filopodia or microspikes. These structures are involved in cell attachment, migration and neurite growth. Filopodia initiation and neural growth depends on cytoskeletal dynamics regulated to a large extent by the small molecular weight GTPases of the Rho family. Here, we describe the individual morphogenic activity of the integral membrane proteins Plasticity Related Genes also termed Lipid Phosphate Phosphatases Related genes (PRG 1-5 or LPPR 1-5). They are differentially expressed in the developing brain and re-expressed in regenerating axons after a lesion. In particular, PRG3 induces the formation of filopodia and promotes axonal growth. The sequence of PRG3 is highly related to PRG5 which also promotes morphological changes in neurons. However, our comparative analysis revealed a hierarchy with PRG3 displaying the strongest outgrowth promoting activity among the entire PRG family.

Transgenic adult mice with constitutive PRG3 expression displayed strong axonal sprouting distal to a spinal cord lesion. Moreover, fostered PRG3 expression promoted complex motor-behavioral recovery compared to wild type controls as revealed in the Schnell swim test (SST). Thus, PRG3 emerges as a developmental RasGRF1-dependent conductor of filopodia formation and axonal growth enhancer. PRG3-induced neurites resist brain injury-associated outgrowth inhibitors and contribute to functional recovery after spinal cord lesions. Here, we provide evidence that PRG3 operates as an essential neuronal growth promoter in the nervous system. Maintaining PRG3 expression in aging brain may turn back the developmental clock for neuronal regeneration and plasticity.

Link: http://dx.doi.org/10.18632/aging.101066

Life span has been steadily increasing these past three decades, a trend made clear in the paper I'll point out today. Yet when it comes to the scope of history, the state of the present, and the future ahead, most people are quite pessimistic. Millennialism never really goes away. The past is seen in rose-tinted hues, the present is experienced against a backdrop of media emphasis on the fearful and the terrible, and the future is commonly painted as a descent into the pit. Yet in truth we live in an age of tremendous positive progress, in which wealth, access to medicine, security, comfort, and healthy longevity are on average increasing year by year. This has been true for more than two centuries in some parts of the world, those first into the industrial revolution, and certainly for at least a lifetime elsewhere. When it comes to biotechnology and medicine, there is a massive shift underway, a gathering of forces for even greater progress. Computing, materials science, and the life sciences are all accelerating, and nowadays researchers are turning their attention towards the treatment of the causes of aging rather than merely patching over and slightly slowing its consequences. The future of human health will be far more than a simple continuation of the gentle upward trend of the past. Great leaps lie ahead.

We're all aware that the past few decades have seen improved health and longevity across most of the world. This is as much a matter of growing wealth as it is a combination of new medicine made better and old medicine made cheap. Many regions are far wealthier today than even a generation ago, and that makes a sizable difference in the statistics of health and mortality: better control over infectious disease, better nutrition, greater awareness of common health practices, less exposure to pollution, and so on and so forth, a longer list than simply greater access to modern medical technology throughout life. Where do the statistics of life and death come from, however? As it happens, there is a fair-sized industry of researchers who mine and manage human mortality data from around the world. It is a massive undertaking, made challenging by the poor nature of much of that data on mortality, and especially mortality due to age-related disease, in many parts of the world. Even in wealthier countries, until fairly recently data on the oldest people was notably inaccurate, characterized by a tendency for medical staff to enter "old age" or similar general category as a cause of death rather than something more specific. Cleaning up large-scale databases and obtaining good statistical results with a high confidence of correctness and utility is a specialized business.

The open access paper linked below gives some idea of the sort of toil that goes into pulling together mortality data from countless reporting bodies into a useful set of working data. You should certainly click through and take a look at the full text, particularly the explanations (complete with diagrams and flow charts) of how researchers go about building the analysis from raw data. Given the doom-laden zeitgeist of this age of ours, as much of the blurb is concerned with inequality, healthcare costs, and regional declines as it is with simply presenting the data. It is unarguably the case, however, that the state of medicine and health has greatly improved over the past three decades, and that process of improvement continues. Progress is the true spirit of the age, for all that many do not want to see it. That progress is both good and necessary, as there is much left to be accomplished in the quest to end suffering; the tools to achieve an end to disease, step by step, are both foreseeable and in some cases already under development. The more of that, the better.

Global, regional, and national life expectancy, all-cause mortality, and cause-specific mortality for 249 causes of death, 1980-2015: a systematic analysis for the Global Burden of Disease Study 2015

Comparable information about deaths and mortality rates broken down by age, sex, cause, year, and geography provides a starting point for informed health policy debate. However, generating meaningful comparisons of mortality involves addressing many data and estimation challenges, which include reconciling marked discrepancies in cause of death classifications over time and across populations; adjusting for vital registration system data with coverage and quality issues; appropriately synthesising mortality data from cause-specific sources, such as cancer registries, and alternative cause of death identification tools, such as verbal autopsies; and developing robust analytical strategies to estimate cause-specific mortality amid sparse data. The annual Global Burden of Disease (GBD) analysis provides a standardised approach to addressing these problems, thereby enhancing the capacity to make meaningful comparisons across age, sex, cause, time, and place.

Global life expectancy at birth increased by 10.2 years, rising from 61.7 years in 1980 to 71.8 years in 2015, equating to an average gain of 0.29 years per year. By 2015, male life expectancy had risen by 9.4 years, increasing from 59.6 years in 1980 to 69.0 years, whereas female life expectancy improved by 11.1 years, climbing from 63.7 years to 74.8 years. On average, an additional 0.27 and 0.32 years of life were gained per year for males and females, respectively, since 1980. Global gains in life expectancy were generally gradual but steady, although catastrophic events, including the Rwandan genocide and North Korean famines, and escalating mortality due to HIV/AIDS, had worldwide effects on longevity. Slower gains were achieved for life expectancy at 50 years, or the average number of additional years of life 50 year olds can anticipate at a given point in time. On average, 50-year-old females saw an increase of 4.5 additional years of life since 1980, and 50-year-old males experienced an increase of 3.5 years. Total deaths increased by 4.1% from 2005 to 2015, rising to 55.8 million in 2015, but age-standardised death rates fell by 17.0% during this time, underscoring changes in population growth and shifts in global age structures. The result was similar for non-communicable diseases (NCDs), with total deaths from these causes increasing by 14.1% to 39.8 million in 2015, whereas age-standardised rates decreased by 13.1%. Globally, this mortality pattern emerged for several NCDs, including several types of cancer, ischaemic heart disease, cirrhosis, and Alzheimer's disease and other dementias.

At the global scale, age-specific mortality has steadily improved over the past 35 years; this pattern of general progress continued in the past decade. Progress has been faster in most countries than expected. Against this background of progress, some countries have seen falls in life expectancy, and age-standardised death rates for some causes are increasing. Despite progress in reducing age-standardised death rates, population growth and ageing mean that the number of deaths from most non-communicable causes are increasing in most countries, putting increased demands on health systems.

It is always a good idea to look closely at the biochemistry involved in any potential Alzheimer's disease therapy that shows promise in mouse models. There is perhaps more uncertainty for Alzheimer's than most other age-related conditions when it comes to the degree to which the models are a useful representation of the disease state in humans - which might go some way towards explaining the promising failures that litter the field. In the research here, the authors are aiming to suppress a step in the generation of amyloid-β, one of the proteins that aggregates in growing amounts and is associated with brain cell death in Alzheimer's disease. They achieve this goal using gene therapy to increase the level of PGC-1α, which in turn reduces the level of an enzyme involved in the production of amyloid-β. Interestingly, increased levels of PGC-1α have in the past been shown to produce modest life extension in mice, along with some of the beneficial effects to health associated with calorie restriction.

Current therapies for Alzheimer's disease (AD) are symptomatic and do not target the underlying amyloid-β (Aβ) pathology and other important hallmarks including neuronal loss. PPARγ-coactivator-1α (PGC-1α) is a cofactor for transcription factors including the peroxisome proliferator-activated receptor-γ (PPARγ), and it is involved in the regulation of metabolic genes, oxidative phosphorylation, and mitochondrial biogenesis. We previously reported that PGC-1α also regulates the transcription of β-APP cleaving enzyme (BACE1), the main enzyme involved in Aβ generation, and its expression is decreased in AD patients. We aimed to explore the potential therapeutic effect of PGC-1α by generating a lentiviral vector to express human PGC-1α and target it to hippocampus and cortex of APP23 transgenic mice at the preclinical stage of the disease.

Four months after injection, APP23 mice treated with hPGC-1α showed improved spatial and recognition memory concomitant with a significant reduction in Aβ deposition, associated with a decrease in BACE1 expression. hPGC-1α overexpression attenuated the levels of proinflammatory cytokines and microglial activation. This effect was accompanied by a marked preservation of pyramidal neurons in the CA3 area and increased expression of neurotrophic factors. The neuroprotective effects were secondary to a reduction in Aβ pathology and neuroinflammation, because wild-type mice receiving the same treatment were unaffected. These results suggest that the selective induction of PGC-1α gene in specific areas of the brain is effective in targeting AD-related neurodegeneration and holds potential as therapeutic intervention for this disease.

Link: http://dx.doi.org/10.1073/pnas.1606171113

Researchers here demonstrate a method of interfering in the spread of alpha-synuclein aggregates, an approach that may slow the progression of synucleopathies such as Parkinson's disease. Like a number of other age-related neurodegenerative conditions, these are associated with and probably driven by the growing presence of specific misfolded or damaged proteins. The ideal approach is to find ways to safely remove these proteins, or understand and resolve the underlying reasons for their accumulation, both of which are paths that are so far proving to be more challenging than expected. Much of the research community remains focused on attempts to alter the late stage biochemistry of disease progression, however, as is the case here, rather than taking aim at root causes. This can be effective, but it is usually going to be much harder to prevent pathology without fixing the root causes than it is by going after those root causes.

Researchers report they have identified a protein that enables a toxic natural aggregate to spread from cell to cell in a mammal's brain - and a way to block that protein's action. The new findings hinge on how aggregates of alpha-synuclein protein enter brain cells. Abnormal clumps of alpha-synuclein protein are often found in autopsies of people with Parkinson's disease and are thought to cause the death of dopamine-producing brain cells. A few years ago, researchers published evidence for a novel theory that Parkinson's disease progresses as alpha-synuclein aggregates spread from brain cell to brain cell, inducing previously normal alpha-synuclein protein to aggregate, and gradually move from the "lower" brain structures responsible for movement and basic functions to "higher" areas associated with processes like memory and reasoning. "There was a lot of skepticism, but then other labs showed alpha-synuclein might spread from cell to cell."

The researchers knew they were looking for a certain kind of protein called a transmembrane receptor, which is found on the outside of a cell and works like a lock in a door, admitting only proteins with the right "key." They first found a type of cells alpha-synuclein aggregates could not enter - a line of human brain cancer cells grown in the laboratory. The next step was to add genes for transmembrane receptors one by one to the cells and see whether any of them allowed the aggregates in. Three of the proteins did, and one, LAG3, had a heavy preference for latching on to alpha-synuclein aggregates over nonclumped alpha-synuclein. The team next bred mice that lacked the gene for LAG3 and injected them with alpha-synuclein aggregates. "Typical mice develop Parkinson's-like symptoms soon after they're injected, and within six months, half of their dopamine-making neurons die. But mice without LAG3 were almost completely protected from these effects."

Antibodies that blocked LAG3 had similar protective effects in cultured neurons, the researchers found. "We were excited to find not only how alpha-synuclein aggregates spread through the brain, but also that their progress could be blocked by existing antibodies." Antibodies targeting LAG3 are already in clinical trials to test whether they can beef up the immune system during chemotherapy. If those trials demonstrate the drugs' safety, the process of testing them as therapeutics for Parkinsons' disease might be sped up, he says. For now, the research team is planning to continue testing LAG3 antibodies in mice and to further explore LAG3's function.

Link: https://www.eurekalert.org/pub_releases/2016-10/jhm-nts101116.php

One of the more recent innovations in calorie restriction research has nothing to do with the science, and everything to do with figuring out how to pull more funding into the field. There is never enough funding for research in any field: going by how funds flow through our societies, it is easy to say that to a first approximation no-one really cares about progress in medicine. Bread and circuses, yes. Better technologies, better understanding of biology, and less disease, no. There is also a large difference between the funds available for non-commercial research versus money available and interested in investment in for-profit ventures. The latter is at least ten times the former, and much more easily arranged as well. Writing grants and raising philanthropic funding is a considerably harder job than pitching angels and venture firms; more effort for fewer dollars at the end of the day. But without the funding for non-profit research initiatives, there will be no new technologies ready to be carried forward in for-profit companies. It is one of the great frustrations of patient advocacy to know that the owners of countless millions of dollars are sitting on their hands, waiting for viable biotech companies, while the important research projects that will generate those companies struggle to raise hundreds of thousands to sustain shoestring budgets.

Calorie restriction is a particular challenge in this context. It is a lifestyle choice, not a drug or an antibody or something else that the medical industry understands how to package, market, and sell. It is nothing more than eating sensibly and eating less. Anyone can choose to do it. It is free and straightforward and well-documented. Yet the effects on long-term health and aging in ordinary individuals are much larger than anything that can be generated by the presently available panoply of drugs and other interventions. That, I should say, is more a statement on the poor quality of present medicine when it comes to treating aging as a medical condition than it is on the benefits of calorie restriction. It is a case of something being better than nothing: no presently available medicine deliberately addresses the root causes of aging, for all that the first therapies that will do that are in development at various stages. The nature of calorie restriction means that there has been little to no for-profit investment aiming to better characterize its benefits. Rather, all that funding was directed towards mapping the biochemistry and haphazardly testing the established drug libraries to find something that triggered any of the same effects. The search for such calorie restriction mimetics is well documented elsewhere, so I won't dwell on that, beyond noting that the outcome of ten to fifteen years of work and a great deal of money is, so far, nothing of any practical use.

So to calorie restriction itself, and how to obtain for-profit funding for research into eating less, and eating less in an effective way. The innovators here are Valter Longo and colleagues, who have achieved the goal of pulling in for-profit funding on the backs of turning specific implementations of fasting and low-calorie diets into FDA-approved therapies, such as an adjuvant in cancer treatment. The magic of regulation means that companies can manufacture a medical diet on the basis of research, and then use the barriers set up via intellectual property and regulatory pronouncements to charge an inordinate amount for what is, basically, a little bit of food that anyone could throw together after reading the papers to obtain the target calories, protein, micronutrient levels, and so on. That in turn means that the principals of these companies are willing to pay for the supporting research. On the one hand it's a depressing example of the distorted priorities that emerge from regulation of medicine, on the other one feels a certain admiration for Longo et al for having successfully hacked the system to fund the useful results they have produced these past few years. Quantifying the degree to which fasting alters the immune system, and quantifying the degree to which low-calorie diets and fasting are effectively equivalent in altering metabolism, are both helpful new information for those who practice forms of calorie restriction and intermittent fasting. In any case, here is a pointer to the less useful outcome from all of this, which is to say the medical diet. It comes across as a bad parody of itself, but that seems fairly true of most medical diet products.

Introducing ProLon

Industry leading nutritechnology company L-Nutra has announced the release of ProLon, a groundbreaking 5 days per month only natural plant based meal program that nourishes the body while convincing it that it is fully fasting. This is the first time in history that 'Fasting with Food' is possible and is therefore called the Fasting Mimicking Diet (FMD). Developed at the Longevity Institute of the University of Southern California (USC) and under the sponsorship of the National Institute for Aging and the National Institute of Health, ProLon induces the body to protect itself and rejuvenate in response to 5 consecutive days of fasting.

In the latest clinical trial conducted at USC's Longevity Institute, 100 participants on 3 cycles of ProLon (5 days only per month over a 3-month period) showed statistically significant improvements on various health metrics: decrease in body fat; decrease in body weight; preservation of bone density; reduction in fasting glucose and insulin resistance; optimization of cholesterol and triglyceride levels; decrease in IGF-1 (aging marker); decrease in C-reactive protein; elevated mesenchymal/progenitor cells (rejuvenation marker). This 'fasting with food' program features meals ranging from 770 to 1,100 calories per day.

Needless to say you can do all of this yourself, and whether or not you happen to have cancer at the time. It isn't hard to construct and follow a diet to a specific target of calories and nutrients: it just takes the willingness to do it. When presented with the above, and there's more along the same lines if you want to explore the ProLon website, it has to be said that it is more of a challenge than usual to remain optimistic that the first generation of rejuvenation therapies after the SENS model, such as senescent cell clearance, will be able do without the ridiculous marketing language that characterizes present day efforts such as the one above.

Not so very many years ago it was noted that transplanting young ovaries into old mice resulted in extended life. There is still no good understanding of why this happens, and which of the numerous changes produced by this transplantation are most important in determining life span, but researchers here focus on beneficial effects for the immune system. Age-related failure of the immune system negatively impacts a wide range of important functions, including wound healing, destruction of senescent and potentially cancerous cells, and maintenance and support of neural tissues. It also leads to increased levels of chronic inflammation, a factor that contributes to the development of all of the common age-related diseases. Immune system decline is an important component of frailty in old age, so it isn't unreasonable to think that meaningful benefits will be generated by immune system restoration.

As we age, our metabolism slows and our immune system runs out of steam. Older people are more likely to have severe cold and flu symptoms, probably because they have fewer fresh immune cells left. And a slower metabolism means that glucose stays in the blood stream for longer after eating a meal. Over time, high blood sugar levels can damage organs. But experiments in mice suggest that transplanting organs from a younger individual could reverse these changes. Researchers removed the ovaries of 10 mice that were 12 months old and had gone through oestropause, a transition similar to the human menopause. They replaced these with ovaries taken from 60-day old mice - roughly equivalent to people in their early 20s in terms of ageing.

Four months later, the researchers assessed the mouse immune systems. The numbers of immune cells that respond to new infections - called naive T-cells - tend to decline with age, and had already fallen in these mice before surgery. Between the ages of 6 months (before the operation) and 16 months, the number of naive cells in these mice rose by around 67 per cent. Cell counts fell by 80 per cent in untreated mice over the same period. To test metabolism, researchers injected the mice with glucose and measured how long it took for their blood sugar levels to return to normal. The mice with young ovaries removed glucose from their blood faster than untreated mice. The findings build on the team's previous work, which found that mice transplanted with young ovaries in middle age live about 40 per cent longer than their peers, and have healthier looking hearts too. How young ovaries might exert these benefits remains something of a mystery. One theory is that the hormones produced by the eggs inside these ovaries are responsible. But when researchers killed all the eggs inside young ovaries before transplanting them into another set of older mice, they still saw the same benefits. The researchers theorize that some other kind of cell inside the ovary might be responsible for the rejuvenation.

Link: https://www.newscientist.com/article/2108682-young-ovaries-rejuvenate-older-mice-and-extend-their-lifespan/

A supporter recently asked the SENS Research Foundation staff whether the implementation of rejuvenation therapies that follow the SENS model of damage repair would prevent the development of cancer, since cancer is predominantly an age-related disease. Would rejuvenation alone, without any progress towards a comprehensive and effective cure for cancer, be good enough to hold cancer at bay?

It's certainly a good bet that applying rejuvenation biotechnologies to remove, repair, and replace other kinds of aging damage will in some ways make us less vulnerable to cancer. Notably, ablating senescent cells would eliminate the "senescence-associated secretory phenotype" (SASP), which promotes the growth and invasiveness of cancers in several ways, including stimulating early-stage cancer cells to continue replicating, encouraging the growth of new blood vessels needed by cancer cells to supply themselves with fuel and oxygen, and breaking down the physical barriers that prevent them from metastasizing, which is when most cancers become deadly. Also, rejuvenating the aging immune system (by eliminating the dysfunctional T-cells that accumulate with age and rebuilding the atrophied thymus gland) will restore the body's ability to suss out and eliminate cancers as they emerge. But it's also clear that deploying these other rejuvenation biotechnologies won't be enough to eliminate cancer altogether, and that must be our ultimate goal.

First, we already know that cancers can evolve multiple mechanisms to avoid being hit or destroyed by antibodies and immunological factors, and the longer a person lives with proto-cancerous cells (even in the presence of a healthy, young immune system), the longer those cells have to develop ways to evade such an immune system. This is one of the reasons that cancer is an age-related disease, despite the fact that young people can and do certainly get cancer, and despite the fact that many late-life cancers originate with mutations that arise in the body decades earlier. More importantly, perhaps, there is good reason to worry that otherwise-rejuvenated tissues in a body that is still vulnerable to the core processes of cancer may actually become more vulnerable to cancer than they would be under "aging as usual." Consider the following contrasting scientific findings.

On the one hand, it has been shown in animal experiments that when you transplant a pre-formed cancer into an old host, it usually grows more quickly than the same cancer does when transplanted into a young one. This is as you'd expect from things that make the aged host more vulnerable to cancer: senescent cells make it easier for the implanted cancer to take root and spread, and a flagging immune system is less able to root out the invader. On the other hand, when you infect mice with a virus that can cause new cancers to form, it is actually less likely to happen in an old mouse than in a young one - and the tumors that do form grow more slowly, despite the weakened immune system and burden of senescent cells in the older animal. This strongly suggests that something about biological aging itself eventually makes our tissues less prone to forming cancers.

Consistent with this, consider the phenomenon of people (and mice) with mutations in DNA repair genes that cause them to accumulate mutations more rapidly than the rest of us. These people develop an "old" burden of potentially cancer-causing mutations in a body that is otherwise still young. This would be similar to having an otherwise-rejuvenated body in which the problem of age-associated mutations had not been solved by a specific rejuvenation biotechnology. Such people develop what are often very aggressive cancers at much younger ages than is typical in the general population. This suggests that once the mutations needed to form a cancer take hold, even an otherwise-young body is unable to hold the invasion back. Thus, rejuvenating the body will reduce the risk of some cancers (notably, by reversing immunosenescence, clearing out senescent cells, and restoring the structural integrity of the extracellular matrix of our tissues). In other ways, however, rejuvenation could restore the host tissues' intrinsic vulnerability to forming new cancers, and to that extent make cancer more of a risk: all those fresh, proliferation-competent cells, and a restored signaling environment full of growth factors.

Link: http://www.sens.org/research/research-blog/question-month-15-would-other-rejuvenation-biotechnologies-keep-us-cancer-free

In the research linked below, scientists describe a potentially beneficial point of interference in a tau-related mechanism of neurodegeneration: targeted sabotage of this mechanism can restore lost cognitive function and otherwise turn back some of the effects of a tauopathy, at least in the engineered mouse lineages used. Tauopathies are neurodegenerative conditions characterized by an accumulation of altered forms of tau protein, forming solid fibrils and tangles in brain tissue. Alzheimer's disease is perhaps the most familiar of these conditions, and there is still considerable debate over the degree to which the harm to brain cells and cognitive function is caused by amyloid-β versus tau in that case. For both proteins the situation is somewhat similar: a lot of work focused on how the deposited solid aggregates relate to mechanisms of cell death and dysfunction, as well as why it is that older people have more of these aggregates, and so far frustratingly limited progress towards therapies capable of clearing out these forms of metabolic waste, despite years of large-scale investment. Many researchers are, however, focused less on clearance than on altering the operation of brain biochemistry in the presence of tau and amyloid: finding ways to short-circuit the worst consequences rather than finding ways to remove the root causes. I can't say I think that this is a wise high-level strategy, but it is very prevalent in the research community.

Why does the presence of the insoluble form of tau increase with age? One possibility is shared with amyloid, that the clearance and filtration mechanisms operating on cerebrospinal fluid decline in later life. That might include dysfunction in the choroid plexus, responsible for filtration, or dysfunction in the drainage system of small fluid passageways behind the nose. The creation and removal of these aggregates is actually fairly dynamic, and the outcome only looks like a slow and steadily increase because the imbalance between that creation and removal grows slowly and steadily. Another possible cause of growing levels of tau is the age-related decline in immune function, just as apparent in the brain as elsewhere in the body. Immune cells are responsible for clearing out waste, among many other tasks, and when they are less efficient we might expect levels of all forms of waste between cells to increase. At the detail level of biochemistry and mechanisms, however, a great deal of uncertainty remains. There is considerable debate and a great deal of published research covering efforts to catalog how and why the presence of tau increases with age, and how and why it does so to a larger degree in only some people. It is a complex field, still in progress towards definitive answers.

In the ideal world, this lack of knowledge could be treated as a Gordian Knot and cut with some form of therapy that efficiently removed tau aggregates. That would very quickly and clearly pin down the importance of the role of tau in neurodegenerative disease and cell death. It isn't the chosen strategy for much of the research community, however, and there is typically more of a focus on the class of approach illustrated below, in which downstream mechanisms in a disease brain are mapped and then manipulated. The root cause remains, able to cause harm via any of the other, yet to be mapped consequences: keeping a damaged machine running without repairing that damage is typically much harder than just focusing on repair. It is possible to achieve beneficial outcomes by following this strategy, as is the case here, but they will typically only deal with a fraction of the issue or only slow the progression of the condition. Still, within the context of the strategy chosen here, and with the caveat that work in mouse models for amyloid and tau pathologies has a poor record of success when it comes to making the leap to human medicine, this seems promising. Those in the audience who have followed research into Alzheimer's and amyloid-β over the past decade might find that there are a number of parallels in the results presented here and some of the discoveries made of how amyloid gives rise to harmful effects on cells - also quite indirect in its relationship with the aggregrated solid form of the protein.

Untangling a cause of memory loss in neurodegenerative diseases

Using a mouse model of tauopathy that produces a mutated form of human tau protein, researchers correlated memory deficits with the presence of a fragment of the tau protein. The tau fragment, which is produced when caspase-2 cuts the full-length tau protein at a specific location, was also found at higher levels in the brains of Alzheimer's disease patients compared to healthy individuals of the same age. While the standard hallmark of tauopathies is the appearance in brain tissue of large tangles of abnormal tau protein, it has recently become less clear whether the tangles of tau are actually causing cognitive decline. "In the past, many studies focused on the accumulation of tangles and their connection to memory loss, but the more we learn, the less likely it seems that they are the cause of disease symptoms. The pathological fragment of tau that we have identified resists forming tangles and can instead move freely throughout the cell. Therefore, we decided to look for other mechanisms that could affect synaptic function."

The researchers used fluorescent labeling to track and compare the behavior of normal and mutated tau in cultured neurons from the rat hippocampus, the brain region most associated with learning and memory. Unlike normal tau, both mutated tau and the short fragment produced when caspase-2 cuts tau were primarily found within structures called dendritic spines, where neurons receive inputs from neighboring cells. The overabundance of mutated tau, including the caspase-2-produced fragment, caused disruptions in synaptic function in the spines. The impact on synapses was specific, with no observed effects on the overall structure or survival of the neurons. "It appears that abnormally processed tau is disrupting the ability of neurons to properly respond to the signals that they receive, producing memory deficits independent of tangle formation. Because this effect is occurring without cell death or a loss of synapses, we have a better chance of intervening in the process and hopefully reversing symptoms of the disease."

Caspase-2 cleavage of tau reversibly impairs memory

In Alzheimer's disease (AD) and other tauopathies, the tau protein forms fibrils, which are believed to be neurotoxic. However, fibrillar tau has been dissociated from neuron death and network dysfunction, suggesting the involvement of nonfibrillar species. Here we describe a novel pathological process in which caspase-2 cleavage of tau at Asp314 impairs cognitive and synaptic function in animal and cellular models of tauopathies by promoting the missorting of tau to dendritic spines. The truncation product, Δtau314, resists fibrillation and is present at higher levels in brains from cognitively impaired mice and humans with AD. The expression of tau mutants that resisted caspase-2 cleavage prevented tau from infiltrating spines, dislocating glutamate receptors and impairing synaptic function in cultured neurons, and it prevented memory deficits and neurodegeneration in mice. Decreasing the levels of caspase-2 restored long-term memory in mice that had existing deficits. Our results suggest an overall treatment strategy for re-establishing synaptic function and restoring memory in patients with AD by preventing tau from accumulating in dendritic spines.

There is some evidence for the deposition of misfolded proteins into solid structures known as amyloid to contribute to the development of arthritis. Amyloid is better known for its role in Alzheimer's disease, but there are a number of types of amyloid, each a different misfolded protein, and for many of these the the relationships to age-related disease are still tentative or only partially explored. In recent years transthyretin amyloid has been recognized as important in heart disease and a range of other conditions, for example, but these are quite new discoveries despite the fact that the existence of this type of amyloid has been recognized for a long time. Still, amyloids are one of the characteristic differences between old tissue and young tissue: the research community should be aiming at the development of safe methods of removal for all of them, even in advance of a comprehensive understanding of how exactly they cause harm.

Amyloidosis is a protein conformational disorder in which amyloid fibrils accumulate in the extracellular space and induce organ dysfunction. Recently, two different amyloidogenic proteins, transthyretin (TTR) and apolipoprotein A-I (Apo A-I), were identified in amyloid deposits in knee joints in patients with knee osteoarthritis (OA). However, clinicopathological differences related to those two kinds of amyloid deposits in the knee joint remain to be clarified. Here, we investigated the clinicopathological features related to these knee amyloid deposits associated with knee OA and the biochemical characteristics of the amyloid deposits.

We found that all of our patients with knee OA had amyloid deposits in the knee joints, especially in the meniscus, and those deposits were primarily derived from TTR and/or Apo A-I. Some patients with knee OA, however, had unclassified amyloid deposits. One of our interesting observations concerned the different effects of aging on each type of amyloid formed. The frequency of formation of ATTR deposits clearly increased with age, but that of AApo A-I deposits decreased. Furthermore, we found that ∼16% of patients with knee OA developed ATTR/AApo A-I double deposits in the meniscus. Amyloid deposition may therefore be a common histopathological feature associated with knee OA. Also, aging may induce ATTR formation in the knee joint in elderly patients with knee OA, whereas AApo A-I formation may be inversely correlated with age.

Link: http://dx.doi.org/10.3109/13506129.2015.1115758

SIWA Therapeutics is one of a number of companies that have been around for some years, working away at the problem of senescent cells and their contribution to age-related disease at a slow pace. It is probably the case that some of these initiatives will raise new funding and be invigorated as a result of Oisin Biotechnologies and UNITY Biotechnology entering this area, as well as the recent research results showing life extension and other benefits in mice as a result of senescent cell clearance. The principals at SIWA, however, are in this release emphasizing cancer treatment rather than rejuvenation or slowing the pace of aging. This makes sense from a business perspective if you consider where most of the money is in medical research and development. Aging research has always been the poor cousin in comparison to the better established institutions. While effective treatments for aging will be massively more lucrative than effective treatments for cancer, as the target market is pretty much every individual over the age of 30, it requires investment to build those treatments. That is easier to obtain if cancer is involved.

SIWA Therapeutics today reports results of its recent in vivo preclinical study which showed that its monoclonal antibody for removing senescent cells, SIWA 318, significantly inhibited tumor metastasis. Importantly, there were no observable adverse effects from the treatment and no increase in tumor growth over the control group. "These results suggest that the removal of senescent cells may become a therapeutic approach against metastatic cancers. Based on data we and the rest of the scientific community have generated over the last several years, the evidence is clearly mounting that senescent cells are causally implicated in the manifestation and progression of many diseases including cancer metastasis."

The study was done in a BALBc 4T1 metastatic breast cancer mouse model. Mice were grouped to receive 5 ug/g, 10 ug/g, or saline injections two times daily for three weeks. A fourth group received no treatment. At 23 days, when the study ended, the 10ug/g group showed 30% fewer metastatic lung foci compared to the control. The new data are consistent with earlier results in which we showed that SIWA 318 significantly increased muscle mass in normally aged CD-1 mice as well as significantly reducing the level of p16INK4a expression, a validated biomarker of senescent cells. Based on the results SIWA has generated to date, the company is optimizing a humanized form of SIWA 318, and planning additional preclinical studies.

Link: http://www.siwatherapeutics.com/siwa-announces-data

Use of ultrasound as a tool is commonplace in medicine these days, with applications ranging from tissue imaging to breaking up dental plaque to destruction of kidney stones. Many of the effects, actual and potential, at the cellular level are still being explored, however, and they range from the merely intriguing to the very promising. For example, ultrasound appears to speed wound healing in aged skin. More relevant to the research presented here, ultrasound applied to the brain makes the blood-brain barrier leak a little, enough to spur the immune system into greater productive activity. In mice this has been shown to improve cognitive function as well as produce some clearance of the metabolic waste known as β-amyloid that is associated with Alzheimer's disease.

There are lengthy and poorly mapped chains of cause and effect spanning the gap between the application of ultrasound and end results such as amyloid clearance. Which mechanisms are relevant, and how exactly the ultrasound produces the end results of interest, is a line of work that remains very open to hypothesis, competing evidence, and debate. If we consider the effects on the blood brain barrier noted above, it is worth bearing in mind that growing age-related dysfunction and leakage in this structure is thought by many in the field to be a part of the problem in the aging brain. The purpose of the barrier, which lines blood vessels in the brain, is to keep the environment of the brain insulated from that of the rest of the body. Leakage encourages greater levels of neural inflammation and contributes to early development of Alzheimer's disease. So how is it that brief disruption can be as beneficial as long-term disruption is harmful? Nothing is simple when it comes to cellular biochemistry and the progression of aging.

The question of mechanisms is particular pronounced in the research linked below, in which researchers examine the fine structures of dendrites in one area of the brain and how those structures change over time. Dendrites are a part of the structure of the synapses that link neurons into networks. They are decorated with spines that some research suggests are the form in which the data of memory is encoded in the brain. Synapses, dendrites, and spines all change over time, and in characteristic ways with aging. With the application of ultrasound, this age-related change appears to be reduced, but there is no shortage of places to start fishing for the reasons why that might be the case. One could build a career simply trying to fill in the gaps in this picture.

Research finds that ultrasound slows brain ageing

Research shows that scanning ultrasound prevented degeneration of cells in the brains of healthy mice. "We found that, far from causing any damage to the healthy brain, ultrasound treatments may in fact have potential beneficial effects for healthy ageing brains. In a normal brain the structure of neuronal cells in the hippocampus, a brain area extremely important for learning and memory, is reduced with age. What we found is that treating mice with scanning ultrasound prevents this reduction in structure, which suggests that by using this approach we can keep the structure of the brain younger as we get older. We are currently conducting experiments to see if this preservation of the brain cell structure will ameliorate reductions in learning and memory that occur with ageing." In the next stage of research, the team will test the effect of ultrasound on the brain structure and function of older mice.

Scanning Ultrasound (SUS) Causes No Changes to Neuronal Excitability and Prevents Age-Related Reductions in Hippocampal CA1 Dendritic Structure in Wild-Type Mice

Recently, our group has reported that repeated scanning ultrasound (SUS) treatments reduced the amyloid plaque pathology in a transgenic mouse model of Alzheimer's disease (AD) and improved hippocampal-dependent spatial memory performance by activating brain-resident microglia. In this approach, ultrasound was combined with microbubbles to disrupt the blood-brain barrier (BBB) which is achieved by mechanical interactions between the microbubbles and the blood vessel wall as pulsed focused ultrasound is applied, resulting in cycles of compression and rarefaction of the microbubbles. This leads to a transient disruption of tight junctions and the uptake of blood-borne factors by the brain, which are likely to have a role in the activation of microglia that were found to take up amyloid into their lysosomes.

However, the short- and long-term effects of SUS treatment on individual neuronal action potential (AP) firing and dendritic morphology have not been investigated. To address this issue, we evaluated the physiological effects of both a single and multiple SUS treatments on short- and long-term neuronal excitability, dendritic morphology and dendritic spine densities in the CA1 region of the hippocampus of wild-type mice. This allowed us to determine the effect of different SUS treatments in a non-disease state system before eventually moving to a more complicated disease model, where alterations in neuronal function are already present at an early age. For example, reductions in dendritic spine density, AP firing, synaptic activity and long-term potentiation (LTP) have all been reported to occur in amyloid-depositing mouse models of AD.

In our study using wild-type mice, we found that the different SUS treatment regimes had no deleterious effect on neuronal function or morphology. In addition to this we made the interesting observation that repeated SUS treatments prevented reductions in the dendritic complexity and length of CA1 pyramidal neurons that occur in age-matched sham-treated wild-type mice over the course of three months, while a reduction in dendritic spine density was not halted. Taken together, these findings suggest that multiple SUS treatments ameliorate a reduction in the total number of dendritic spines per neuron. A more extensive follow-up study will determine, whether SUS treatments improves cognition in aging mice and what the underlying mechanism is of such an effect.

Age-associated reductions in the structure of neuronal dendritic trees have previously been reported in a range of brain areas and species. However, our understanding of changes in dendritic tree arborization in the hippocampus is less advanced, where both increases and decreases in CA1 pyramidal dendritic length and complexity have previously been reported. While a number of differences exist between these reports and the current work, perhaps the most important is the duration of ageing over which changes in dendritic tree structure was quantified (approximately 1.5 years versus 3 months in the current study). This is a limitation of the current study when evaluating changes in dendritic structure associated with ageing. Further experimentation will be required to assess changes in dendritic tree structure over longer time periods. Despite this, it is evident that multiple SUS treatments are able to prevent reductions in dendritic structure.

Also, the question of how SUS preserves dendritic structure remains to be determined. One possibility is that microglia may play a role, because SUS treatment has previously been reported to activate this cell-type in mouse models as well as in wild-type mice. Microglia constantly probe their local environment and secrete factors that alter neuronal signalling. During activation they can also modify synaptic connections, the key mediators of learning and memory, by increasing the expression of neurotrophins such as brain-derived neurotrophic factor (BDNF). In fact, a recent study has reported that microglia mediate synapse loss at an early time-point in Alzheimer's disease mouse models. One possible mechanism for the neurotrophic effect of SUS may therefore be the delivery of endogenously circulating neurotrophic factors from the blood to the brain. Furthermore, ultrasound waves by themselves, without the need for BBB opening, may also contribute to the observed preservation of dendritic structure, as increased BDNF expression has been reported following ultrasound application. Other neurotrophic factors such as glial cell-derived neurotrophic factor (GDNF) and vascular endothelial growth factor (VEGF) have also been linked to improve memory performance in rats following ultrasound treatment.

Researchers here present a potential way to slow the progression of heart failure. They have identified one of the proximate causes of pathology, a change in the gene expression of ANGPTL2 that accompanies aging or damage in heart tissue. Suppressing this signal improves function and slows the decline. This, like many of today's potential therapeutic approaches, is compensatory in nature. It doesn't address the underlying reasons for the identified change, but seeks to adjust the behavior of damaged tissues to be more youthful despite that damage. It cannot fix the problem, it can only slow down the inevitable; arguably other approaches that do address the root cause damage should have a higher priority.

Heart failure occurs when heart function is reduced making it no longer able to pump enough blood to body. Patients with severe heart failure have a very poor prognosis, with a five-year survival rate of 50-60% despite advances in modern medicine and medical technology. Researchers found that cardiac muscle cells that were from heart failure patients, were aged cells, or were under the stress of high blood pressure had increased production and secretion of the protein ANGPTL2. The research team previously reported that excessive secretion of the ANGPTL2 protein by aged or stressed cells causes chronic inflammation and promotes the development of lifestyle-related diseases such as atherosclerotic disease, obesity, diabetes, or cancer. ANGPTL2 is also related to heart failure. Excessive ANGPTL2 secretions by cardiac muscle cells impair important functions, such as intracellular calcium concentration regulation and energy production, that help maintain the contractile force of the heart. On the other hand, moderate exercise reduces the production of ANGPTL2 in cardiac muscle cells which helps keep the heart healthy.

"We found that ANGPLT2 is significantly involved in heart failure. Among knockout mice that could not produce the protein, the development of heart failure was suppressed in a manner similar to moderate exercise. Furthermore, we genetically engineered a non-pathogenic virus which was designed to infect cardiac muscle cells and reproduce a special RNA molecule that inhibited the production of the ANGPTL2 protein." This new gene therapy in the heart failure mouse model was successful in suppressing ANGPTL2 production in cardiac muscle cells thereby reducing the pathological progression of heart failure. Additionally, in cardiac muscle cells that were differentiated from human induced pluripotent stem cells, the suppression of ANGPYL2 promoted calcium concentration regulation and enhanced energy production. It is considered that the newly developed gene therapy may also be effective for human heart failure patients. Current treatment for heart failure is mainly symptomatic. The gene therapy developed here is expected to become a fundamental treatment that corrects the mechanism of reduced heart function itself.

Link: https://www.eurekalert.org/pub_releases/2016-10/ku-dag101116.php

Lifespan is length of life, while healthspan is length of healthy life. Are they strongly coupled? Is it possible to arrive at treatments that greatly alter one without much altering the other? A related concept is something that many researchers believe (or at least claim in public) that they are aiming for: compression of morbidity, in which healthspan is extended without lifespan being extended. It is hard to say how much of that is driven by the desire to avoid talking about life extension in the context of research, however, versus an earnest belief in the plausibility of the outcome. On the other side of that coin, it does seems plausible that the present bad strategy of trying to compensate for outcomes or ameliorate proximate causes of age-related disease - rather than address their root causes, the cell and tissue damage that causes aging - could be acting to marginally extend lifespan without extending healthspan. These are approaches that, at best, make suffering a chronic age-related condition a somewhat slower, somewhat less damaging process. It is a very expensive path to small gains, however. Keeping a damaged machine running without repairing that damage is a challenging undertaking, and far from the best approach to the problem.

Interventions that extend longevity in model laboratory organisms have proliferated. Traditionally, such interventions have been assumed to retard aging itself based on their ability to increase mean and maximum lifespan. The emphasis on longevity metrics alone made some sense in that longevity seemingly provides an unambiguous endpoint that has been assumed to be necessarily correlated with a general age-related physiological decline. While this may often be the case, it is not necessarily so. Indeed, human females live longer lives than males, but also suffer greater age-related morbidity by a number of measures. In laboratory species, long-lived worm genotypes are often outcompeted by shorter-lived genotypes and some evidence suggests that by a number of measures some long-lived worm genotypes are less healthy than the standard genotype even relatively early in life. As a major goal of basic aging research is to develop interventions that will enhance and prolong health in humans, it would be beneficial to the field to determine for all model organisms, which interventions extend health and which extend only life.

Because efforts to develop a cognate battery of tests to assess healthspan in mice and other model organisms have met with varying degrees of success we have taken a different approach. We feel that important indicators of health that can be commonly addressed in humans and in mice can be roughly categorized as those associated with age-related decreasing strength and mobility and those associated with decreasing cognitive capabilities. To this end, we present here an analysis of age-related change in commonly measured, noninvasive parameters associated with age-related changes in energetics, strength and mobility in the commonly used C57BL/6 mouse strain, and we determined to what extent these health parameters were associated with premature death. We measured age-related changes in healthspan in male and female mice assessed at 4 distinct ages (4 months, 20 months, 28 months and 32 months). Correlations between health parameters and age varied. Some parameters show consistent patterns with age across studies and in both sexes, others changed in one sex only and others showed no significant differences in mice of different ages. Few correlations existed among health assays, suggesting that physiological function in domains we assessed change independently in aging mice. With one exception, health parameters were not significantly associated with an increased probability of premature death. Our results show the need for more robust measures of murine health and suggest a potential disconnect between health and lifespan in mice.

Link: http://dx.doi.org/10.18632/aging.101059

Cell therapies involving transplantation from immune-matched donors go a long way back; think of the bone marrow transplants used in a variety of circumstances, for example. These were a way to ferry across stem cells before it was possible to extract and manage those stem cells in a clinical setting, and the approach is sufficiently advantageous and practiced to remain in use, even as cell based regenerative medicine is reaching the clinic. In the research I'll point out today, scientists take a little of that older world of patient matching to avoid immune rejection and a little of the new world of using small, easily obtained cell samples from a donor, such as blood or skin, to reprogram and culture a large number of cells of the desired type for transplantation. In this case they turn this mixed approach to heart regeneration, and demonstrate the ability to produce benefits following heart attack in monkeys.

The heart is not a very regenerative organ in mammals. Mammalian tissues span a range of willingness to heal, from the liver at one extreme, capable of regrowing lost sections, to the brain and the heart at the other, both of which exhibit little ability to recover from injury. Both ends of the range make for interesting targets for regenerative research: the liver because it seems like an easier starting point, and the brain and the heart because any improvement is significant given the present situation. Cell therapies for the heart have been underway within and outside the formal regulated system of trials for more than fifteen years, but at this point the effectiveness of the various strategies that have arisen is still something of a question mark. Better than nothing, but how much better? A wider range of approaches is available via medical tourism than has been rigorously tested, and the rigorous tests in trials and animal models have exhibited a sizable variation in outcomes. It seems clear that the methodology used is a very important determination of the outcome given the present state of the field: you can't just throw stem cells into a patient and hope for the best. That said, that strategy actually does seem to work fairly well when well-established and well-characterized cell types are used and the goal is reduction of chronic inflammation, which is why there is a high expectation of benefits to result from mesenchymal stem cell therapies for age-related joint pain and similar issues. Regenerative therapies for organs like the heart are a whole other ball game, however, and still a work in progress.

Stem cells regenerate damaged monkey heart

Cardiac muscle cells grown from the stem cells of one macaque monkey can be used to regenerate the hearts of other macaques. The transplanted cells improved the heart's ability to contract after an induced heart attack and integrated with no sign of rejection by the recipient's immune system. However, the recipient's heart did suffer from an irregular heart beat in the first four weeks after the transplant, but this passed and was non-lethal. Researchers used cardiac muscle cells derived from induced pluripotent stem cells (iPSC-CMs) from a donor instead of the patient's own cells. Donor cells are considerably easier to manufacture but increase the risk of being rejected by the recipient's immune systems. The scientists overcame this by matching a surface protein on the donor and recipient's cells that is used by the immune system to recognize foreign cells.

"We found that monkey iPSC-CMs or cardiac muscle cells derived from induced pluripotent stem cells survived in the damaged monkey heart and electrically coupled with the host heart. In addition, the heart's ability to contract was partially recovered by the transplantation. We had a hard time handling monkey iPS cells. Unlike human iPS cells, they are somewhat tricky. The condition of iPS cells are critical for generating high purity cardiac muscle cells. Also, it took a long time to get grafted cardiac muscle cells to survive in the recipients. In addition to daily treatments of immunosuppressant drugs, we made sure the surface protein major histocompatibility complex (MHC), which is used by the immune system to recognize foreign cells, was carefully matched on the donor and recipient's cells. Human embryonic stem cell-derived cardiac muscle cells have already been used in clinic as a new therapy for post myocardial infarction (MI) heart failure. But I think it will take at least a couple of years for this treatment to become more widely-used."

Allogeneic transplantation of iPS cell-derived cardiomyocytes regenerates primate hearts

Induced pluripotent stem cells (iPSCs) constitute a potential source of autologous patient-specific cardiomyocytes for cardiac repair, providing a major benefit over other sources of cells in terms of immune rejection. However, autologous transplantation has substantial challenges related to manufacturing and regulation. Although major histocompatibility complex (MHC)-matched allogeneic transplantation is a promising alternative strategy, few immunological studies have been carried out with iPSCs. Here we describe an allogeneic transplantation model established using the cynomolgus monkey (Macaca fascicularis), the MHC structure of which is identical to that of humans. Fibroblast-derived iPSCs were generated from a MHC haplotype (HT4) homozygous animal and subsequently differentiated into cardiomyocytes (iPSC-CMs). Five HT4 heterozygous monkeys were subjected to myocardial infarction followed by direct intra-myocardial injection of iPSC-CMs.

The grafted cardiomyocytes survived for 12 weeks with no evidence of immune rejection in monkeys treated with clinically relevant doses of methylprednisolone and tacrolimus, and showed electrical coupling with host cardiomyocytes. Additionally, transplantation of the iPSC-CMs improved cardiac contractile function at 4 and 12 weeks after transplantation; however, the incidence of ventricular tachycardia was transiently, but significantly, increased when compared to controls. Collectively, our data demonstrate that allogeneic iPSC-CM transplantation is sufficient to regenerate the infarcted non-human primate heart; however, further research to control post-transplant arrhythmias is necessary.