Fight Aging! Newsletter, May 20th 2024

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Notes from the Rejuvenation Startup Summit in Berlin, May 2024

Repair Biotechnologies was invited to present at this year's Rejuvenation Startup Summit in Berlin, and so my CSO Mourad Topors and I attended. There were more people present this year than were at the already busy 2022 event. This is perhaps an indication of a still growing interest in the longevity industry as it expands, particularly given the present poor market for investment in biotechnology companies. Investors are tending to stay home this year, but nonetheless there was a fair sized crowd in attendance.

Michael Greve's Forever Healthy Foundation hosts the Rejuvenation Startup Summit, and he gave the opening talk, framing the point of the exercise. The longevity industry will clearly become one of the world's largest industries, growing to become the majority of all medicine, given that every older individual is a potential customer. The hundred or more biotech startups that presently make up the longevity industry will collectively demonstrate that this field works, that it is viable, that we can slow and reverse aging. The first proven therapies will usher in a great increase in interest, investment, and participation in the longevity industry. The purpose of this conference series is to help to make that future happen: networking makes the world turn, particularly in the world of biotech investment.

The keynote was provided by Mehmood Khan of the Hevolution Foundation, slowly but steadily deploying Saudi Arabian sovereign wealth into aging research and the longevity industry. Hevolution is a non-profit organization, and plans to put the returns from its investments into further research and development to advance the field. The organization has a fairly conservative viewpoint that is focused on addressing the failure of increases in healthy life span to keep up with overall life span - a focus on compression of morbidity. The financial burden of a growing older population is unsustainable, the existence of the present demographic transition to a larger older population is a driving concern. The current approach to age-related disease isn't working and must change. This conservative viewpoint is one that sees it as very hard to make a gain of few years of healthy life when that gain must be made across the population as a while. Making the technology is perhaps the easier part when compared against the social, realpolitik considerations of how to scale the technology and provide access to it as a public health measure, a low cost therapy. This philosophy explains much of why they focus on the technologies and approaches that they do: mTOR inhibitors that might add a year of life at low cost can better meet their goals than the development of much more advanced therapies that could achieve greater extension of life, but would require decades of work to bring down in cost and scale out to mass availability. Khan made the point that scaling requires the participation of Big Pharma, but Big Pharma is not yet a part of the longevity industry; bringing them into the fold is a task yet to be accomplished. He closed by noting the scale of the disconnect between the cost of aging and the funds available for research. Hevolution has provided 250m in the past 18 months to research institutions that include the Buck Institute, making them the second largest source of funds after the US government - and this is woefully little for the task at hand.

Otto Kanzler of Rockfish Bio opened with an outline of just how bad degenerative aging is: the cost of coping, the disability, the mortality, the lost productivity. The company works on clearance of senescent cells, but while noting that senolytic therapy development is overall very promising, there are barriers to clinical translation. Senescent cells differ considerably by origin, tissue, and stage of senescence. Thus first generation therapies are not effective in clearing all senescent cell types, not selective enough. Further, indication choice is a challenge for any senolytics company, as it might initially seem that there are many options, few are in fact good options from the point of view of cost, difficulty of the discussion with regulators, ability to directly connect senescence to disease mechanisms, and so forth. A big problem is that there are no good non-invasive biomarkers for the burden of senescent cells, either globally or in specific tissues. The company's development program is derived from the realization that senescent cells have increased phospholipase A2 (PLA2) activity. PLA2 is an inducer of apoptosis, but senescent cells convert PLA2 to evade that fate. This is similar to a number of other mechanisms in senescent cells: the cells appear primed for apoptosis, but actively resist it. Rockfish Bio targets this PLA2 conversion with a small molecule, selectively inducing apoptosis in senescent cells as a result. Treatment of mice has produced an extension of life. Rockfish Bio is also collaborating with another industry company to produce a biomarker based on circulating miRNA levels that can measure burden of senescent cells.

Marco Quarta of Rubedo Life Sciences, another senolytics company, also noted the heterogenity of the senescence state, and the problems that this causes in the search for effective therapies. Rubedo has create a drug discovery platform to identify targets for different senescent cell types, and have built up a portfolio of targets and drug candidates. They recently raised significant funding for their first clinical program, focused on skin condition such as atopic dermatitis and psoriasis in which senescent cells are likely important, and where topical therapies can be applied. Like other senolytics companies Rubedo is motivated by the poor selectivity of existing therapies like the dasatinib and quercetin combination, and the off-target effects on non-senescent cells. The goal for Rubedo is to produce drug candidates that are far more selective for specific subsets of senescent cells. At this point, the company expects to start clinical trials in 2025.

Alexander Schueller of cellvie discussed the origins of the company's work on mitochondrial transplantation. Mitochondrial transplantation was used in a clinical trial for children with ischemic heart injury that put them on life support, and the results demonstrated that this approach can work to prevent death and permanent injury. The company was formed to broaden the use of mitochondrial transplantation for all forms of ischemia-reperfusion (IR) injury. A key part of IR injury is dysfunction and damage to mitochondria, but timely delivery of replacement mitochondria prevents much of the cascade of damage resulting from IR injury. The company aims at kidney transplantation as first IR injury situation, as preserving the function of donor kidneys provides the fastest path to a clinical proof of concept that will encourage others to expand this field. The company is presently working towards the development of good manufacturing practice (GMP) protocols for manufacture of harvested mitochondria, with the aim of moving from the use of autologous mitochondria to off the shelf mitochondria that are frozen for storage. Tests have been conducted in pig models that undergo 90 minutes of ischemia to the kidneys followed by treatment with human mitochondria. Biomarkers of kidney function have shown considerable improvement in the treated pigs. Schueller commented on some of the challenges inherent in obtaining funding, in part because the mechanisms underlying the benefits of mitochondrial transplantation are not fully understood. The company has thus been working on obtaining a better understanding, and has shown that uptake of new mitochondria via endocytosis triggers both mitophagy and mitogenesis, improving the situation for native mitochondria. This may not be the only mechanism. The company has also conducted proof of concept research into using mitochondria as a vector for gene therapy, as mitochondria tend to accumulate in the first downstream major organ after intravenous delivery.

Greg Fahy of Intervene Immune gave an update on their work on the reversal of thymic involution. The thymus atrophies, first after puberty, and then more slowly throughout the rest of life, leading to a near complete lack of active tissue as early as age 50 in many cases. The capabilities of the adaptive immune system slowly collapse, lacking the supply of new T cells generated in the thymus - and so the risk of death from immune-related causes rises precipitously after age 50. Thymus transplant from young donors to aged animals has been shown to extend life and restore immune function. Intervene Immune used a growth hormone / DHEA / metformin combination in small human trials, the choice of approach chosen in part to try to gain a rapid approval from regulators. The results from the first TRIIM trial were published in 2019, and included modest reductions in extrinsic and intrinsic epigenetic age. TRIIM-XA was an extension and expansion of that trial, including 26 participants. It is now complete and results are being analyzed. The COVID-19 pandemic occurred during TRIIM-XA, and Fahy speculated on whether this would have had any impact on the results via consequences of vaccination. In preliminary data, TRIIM-XA showed epigenetic age and phenotypic age reversal in a number of different clocks, as well as lower inflammatory markers, increased recent thymic emigrant naive T cells, improved strength and fitness as measured via exercise tolerance, standing test, and VO2max, and lowered body fat percentage and blood pressure. The company is starting to consider adding more agents to the protocol; Fahy tested the addition of a new option on himself recently with positive results.

Eric Verdin of the Buck Institute for Research on Aging gave the second keynote, a selection of ongoing work at the Buck Institute and its relevance to geroscience. He started with the role of senescent cells in aging via their contribution to chronic inflammation and the generation of secondary senescent cells via paracrine signaling. An important implication is that senescent immune cells generate secondary senescence in tissues throughout the body, linking immune aging to near all other aspects of aging. One of the Buck Institute projects focuses on characterizing and measuring senescent cells in the immune system, and finding ways to address it. The researchers have discovered considerable complexity over the course of aging in the changing populations of immune cells of various types and behaviors. Generic markers of cellular senescence show that large proportions of some subpopulations of immune cells have become senescent, for example up to 40% of some memory T cells. These markers of senescence need to be improved upon, however, given the diversity of senescent states. Verdin then moved on to discuss the buildup of lipofuscin with age. The researchers see it as a marker of senescence, at least in the immune system - it is actually a marker of lysosomal stress, characteristic of senescent cells. Their data demonstrates a correlation between lipofuscin burden, age, and other markers of senescence status in T cells. This detailed assessment of immune cell populations has also shown that epigenetic clocks produce different results in different subpopulations of immune cell. As a result, the clocks can be split into measures of extrinsic age (quite variable across immune cell types) versus intrinsic age (not so variable). The intrinsic age clock may be measuring the proportion of senescent cells in immune populations, but this has yet to be robustly demonstrated.

Lou Hawthorne of NaNotics works on targeting the soluble proteome for selective clearance. Nanots are engineered nanoscale sponges that can bind and soak up specific soluble proteins outside cells only, and are then cleared from the body by macrophages. Nanot binding represents an improvement over antibody approaches, both in specificity and in controlling the degree of depletion. The company can engineer nanots to, in principle, bind near any soluble protein. The initial clinical focus is on clearing soluble forms of TNF and TNF receptor (TNF-R1 and TNF-R2), as well as various interleukins to inhibit runaway inflammation. Inflammatory autoimmune conditions and cancers are the initial indications. All cancers shed TNF receptor fragments as soluble TNF-R1 and TNF-R2 in order to decoy TNF as a part of their immune suppression strategy. Clearing these decoys helps to make the cancer visible to the immune system. There used to be a clinic that employed apheresis to clear soluble TNF receptor fragments in terminal cancer patients, a treatment that achieved 60% response rates. The hope is that the nanot approach will improve on this. Soluble TNF receptor proteins are an undruggable target, so small molecules can't be used here, as they would interfere in necessary functions mediated by the receptors. NaNotics has also collaborated on clearing soluble PD-L1, showing benefits in models. Beyond cancer, the company works on clearance of soluble TNF to treat multiple sclerosis, as soluble TNF and soluble TNF-R1 both interfere in oligodendrocyte-mediated remyelination. In MS there is too much soluble TNF. In closing, Hawthorne mentioned that the company is now working on a polymer core nanot that will be able to last for a long time in circulation. They would like to use this to treat endothelial barrier dysfunction and inflammaging by clearing out the best-known circulating signal molecules involved in these processes.

Dobri Kiprov of Circulate started with an outline of the recent history of parabiosis research, starting with a collaboration with the Conboys. Further research after that supported the use of therapeutic plasma exchange as an approach to treat aspects of aging, the practical way to implement something like parabiosis in humans. Clinicians can remove plasma and substitute in young plasma, but this can produce side-effects. So they instead use 5% albumin in saline. Albumin comes from donor plasma, where the average age of donors is 25 or so. Kiprov argued for the quality of the albumin to likely be an important factor in the effects of parabiosis, given it has immunomodulatory, anti-inflammatory, and antioxidant effects. He outlined a recent clinical trial of therapeutic plasma exchange, which is double blinded and enrolled 40 patients. There was only one adverse reaction over the course of 360 procedures conducted during the trial. The clinicians assessed hand grip and similar values of physical condition, measures of cognitive function, and senescence-associated secretory phenotype (SASP) proteins in circulation. Treatment resulted in some improvement versus controls in all of these. The company continues to analyze the copious study data. Important goals include answering the question of how long the effects last for, as well as how to identify which patients will respond positively to the therapy.

Alejandro Ocampo of Epiterna spent some of his presentation on a sketch of the incentives shaping the longevity industry. Companies are focused on applying their work to specific age-related diseases rather than to aging; they typically don't even test to see if life span is extended in mice as a result of their treatment. This is because of regulatory concerns, in that trials to assess aging will be very costly, and no-one wants to be first to try to take the TAME trial design and convince the FDA to let them do it. So instead companies aim at regulator approval for one age-related disease followed by off-label use. Ocampo is concerned that this approach will leads to the failure of trials for viable anti-aging therapies that happen to be a poor fit for the chosen disease. Also, founders tend to lose control of the company as it moves forward, and if it starts working on one disease it may never change to focus on life extension; this has already happened. Learning from this, Epiterna tries to deliberately work on longevity rather than disease. The company is focused on aging in dogs, and are working to develop supplement based approaches to slowing aging. Why dogs? Because it is the largest companion animal market and there is a much lower regulatory cost and risk than is the case for human medicine, particularly given recent efforts to make regulators accept aging as an indication in animals. Additionally, dogs have a short enough life span to allow proof of effects on aging with a feasible cost. Why supplements? Because of the faster path to market and lower regulatory hurdles. The company has developed a low-cost screening platform that screens compounds for life extension in numerous short-lived species, working through yeast, worms, filies, killifish, and mice. In one year they can run ~3000 molecules in yeast and narrow down to a final 20 in mice that are consistently extending life across these species. The output of this screening will lead to trials in companion dogs, currently planned to last 2-3 years and include as many as a thousand animals.

Lorna Harries of SENISCA works on reprogramming cells by designing and screening oligonucleotides and small molecules that can suppress detrimental alternative splicing of RNA characteristic of aging and cellular senescence. This is a way to produce senotherapeutics that reprogram senescent cells into behaving better, or possibly even exit the senescent state if they are in early stage senescence. This screening platform can in principle be more selective about what type or stage of senescent cells are targeted than existing senolytic drugs. The SENISCA program originated with the unbiased screening of age-related changes in gene expression in samples from hundreds of people, where the results pointed to the importance of RNA processing pathways and altered expression of splicing factors. The company is developing oligonucleotides as therapeutics to target aging in general, and have a codevelopment partnership to develop small molecules for topical use in skin aging. The researchers have developed their own assays for senescent cell burden in tissues and cell cultures, as well as making it possible to distinguish between early and late senescent cell states. SENISCA is initially focused on idiopathic pulmonary fibrosis (IPF) as an indication, and has shown shown reduced senescence, fibrotic markers, collagen deposition, and DNA damage in human IPF patient cells in vitro following treatment. The company has tested intranasal delivery of naked oligonucleotides in mice, and show delivery to lungs, a promising start.

Stephanie Dainow of gave, I'm told, an interesting presentation, particularly given that SENS Research Foundation and are now merging. Unfortunately I had to miss this one. Apologies!

Phil Newman of Longevity.Technology discussed the demographic aging trend as a motivation to work on the treatment of aging as a medical condition, where even a modest slowing of aging could greatly reduce the vast economic cost of ill health in later life. There is a clearly a trend in the science and development, age-slowing, and age-reversing therapies will come into being, and things are going to become very interesting as average life expectancy increases step by step to be far greater than 100 years of age. That future is being built now, but what will it look like, where will the greatest focus fall? We can all speculate, and will all likely be surprised in many ways. Newman moved on to an overview of the present system of medical regulation and reimbursement; how the money flows, the economic incentives for Big Pharma, medical insurance companies, and governments. Chronic disease costs a lot, and therapies to effectively slow or reverse aging will improve the economics for everyone. How long will it be until effective therapies to treat aging exist? This is difficult to predict, but we might be pessimistic when looking at the decades it has taken for some currently popular therapies to move from fundamental research to recognition of value to active clinical development.

Lukas Langenegger of Hemotune showcased their approach to plood purification, improving dialysis techniques to remove specific molecules in blood. As for the NaNotics technology, this offers the ability to selectively remove multiple specific molecules and thus address multiple mechanisms at one time in the case of complex conditions. Hemotune make a machine that allows better, selective blood purification. As in all dialysis, blood runs through the machine. At the core is an exchangeable cartridge of engineered magnetic nanoparticles decorated with antibodies or other binders specific to selected molecules in blood. These nanoparticles, and the molecules newly bound to them, are removed by magnets before blood is returned to the patient. Hemotune is initially targeting sepsis-induced immunosuppression, a lasting condition that follows sepsis, and are working towards a clinical trial to be conducted in a few hundred patients. Secondly, the company has developed a proof of concept for the removal of anti-AAV antibodies. This will in principle enable AAV-based gene therapy to work in patients with existing antibodies. Antibodies prevent repeat dosing, but many patients have preexisting anti-AAV antibodies even prior to a first dose.

Robin Mansukhani of Deciduous Therapeutics presented on their senolytic immunotherapy, a small molecule treatment that produces a lasting alteration in the behavior of invariant natural killer T cells (iNKT cells) to increase their ability to clear senescent cells. iNKT cells coordinate the removal of senescent cells. Explaining the origin of the program, Mansukhani explained that the realization that accumulation of senescent cells is driven by failure of the immune system to clear these cells in a timely fashion led to research aimed at identifying which immune cells were dysfunctional and why. That in turn pointed the way to an intervention to reverse that dysfunction. The animal data generated by Deciduous demonstrates the effective lasting clearance of senescent cells, and a consequent sizable reduction in fibrosis in mouse models of idiopathic pulmonary fibrosis, a far greater effect than is produced by the current standard of care treatment of nintedanib. The company has also shown improvement in type 2 diabetes mouse models. In general, an effective senolytic should have a large value, as it can be applied to near every age-related disease in some way. The next steps for Deciduous are to scale up manufacturing processes and conduct IND-enabling studies. They are also looking into how to replicate the iNKT intervention in the brain, where the immune system is isolated and different, and would thus require identifying a different cell population and form of dysfunction to correct.

Matthew O'Connor of Cyclarity showed a sampling of studies demonstrating that 7-ketocholesterol, a harmful altered form of cholesterol, is associated with cardiovascular disease. At the SENS Research Foundation the staff spent some time looking into how to clear this molecule, and settled on a cyclodextrin based approach - finding ways to adapt existing cholesterol-binding cyclodextrins to only bind 7-ketocholesterol. In the process they produced a platform for cyclodextrin design that might be applied to other goals. Cyclodextrins have many uses, and existing cyclodextrin drugs bind various unwanted molecules to remove them from the body. The industry has a lot of experience in working with them. Cyclarity has shown in vitro that their cyclodrextrin drug can restore function in macrophages induced by 7-ketocholesterol to become foam cells. The company is headed to the clinic: the first GMP batch is produced, and a phase 1 safety trial in healthy volunteers and a smaller number of patients with plaque is set to start this year in Australia.

I presented on our work at Repair Biotechnologies, starting with a brief tour of the data showing that the risk of cardiovascular disease and mortality via stroke and heart attack rises with the burden of atherosclerotic plaque present in the arteries. For example, a Dutch study showed that 5-6 arterial plaques identified by imaging indicates a five-fold increase in risk over those with no visible plaques. The lipid-lowering standard of care (meaning long-term treatment with statins, PCSK9 inhibitors, and the like) does not meaningfully reduce plaque size, however. As little as a 1% reduction in plaque volume leads to a ~20% reduction in stroke and heart attack, but only a fraction of patients can achieve even this much plaque reduction after a year or more of treatment. The average improvement is close to zero. In comparison, the Repair Biotechnologies LNP-mRNA gene therapy can produce a 17% reduction in aortic plaque volume after six weeks of treatment in the LDLR knockout mouse model of accelerated atherosclerosis. Additionally, the therapy removes plaque lipids and encourages plaque stability in the APOE knockout mouse model of atherosclerosis. This therapy works by clearing a toxic excess of free cholesterol in the liver, restoring the liver to homeostasis and producing systemic beneficial effects throughout the body. The company is planning a series A round to fund the path to a first clinical trial in the rare genetic condition of homozygous familial hypercholesterolemia in 2026, with a potential fast track approval leading to off-label use for severe atherosclerosis in the general population.

Brian Kennedy of the National University of Singapore (NUS) opened his presentation with a complaint about the lack of preventitive treatment taking place in the period of healthy life. We have a sickcare system that focuses only the part of life when people are demonstrably unwell. Doing nothing while people are healthy is in fact causing harm, because aging is still progressing towards sickness while people are ostensibly healthy. The programs at NUS focus on the interface between biomarkers and interventions. One example of their work is a broad set of combinatorial studies, in which it was shown that the combination of any two supplements or small molecules that are modestly good on their own can produce any sort of result, bad or good, often bad, and no-one can yet predict in advance what the outcome will be. The NUS researchers conduct various simple interventions in mice while assessing life span and biomarkers, attempting to be rigorous in setting up a cost-effective system to better evaluate the effects of these interventions. Kennedy went on to make the point that we don't know much about widely used medical tourism treatments, meaning stem cell therapies, exosomes, and so forth, and he wants to work with clinics in order to gather data on the outcomes in people undergoing these studies - a matter of using rich people as model organisms, as he said. He also made the point that older people who are in a worse state of health, with an accelerated biological age relative to chronological age, appear to respond better to some interventions. He offered the example of a human alpha-ketoglutarate (AKG) study in supplement users (lacking a control group) in which epigenetic age was reduced. It is unknown as to whether a better relative outcome in less healthy individuals is the case for all interventions. The NUS researchers are repeating this AKG study with a control group, and should have results in 2025. Kennedy noted that AKG delays fertility decline in mice, and speculated on whether this could be a general effect across many interventions, because mechanisms that slow aging should have evolved to specifically slow reproductive aging, while everything else is a side-effect of that outcome. Moving on to aging clocks, the NUS team has produced a metabolomic aging clock, and along the way demonstrated that AKG levels in circulation decline with age. The researchers are also working on several other different clocks built out of combinations of clinical parameters, similar to phenotypic age and using data from the NHANES study, on the grounds that a clock of this nature should produce results that are more directly comprehensible and useful to clinicians.

Alexander Leutner of Cellbricks outlined their approach to tissue engineering. The company has developed a light-based bioprinting process. Laser light is projected into into a dish of bioink, each pulse of light making a tiny volume of the ink solidify. In this way the researchers can construct complex structures layer by layer: build a layer, raise it out of the bioink, build the next layer, and so forth. They can produce vascularized blocks of tissue in this way, and have manufactured functional cartilage, liver, pancreas, breast tissue, and others. They can also create tumor models or other forms of diseased tissue. The company aims to create implantable blocks for reconstructive surgery, such as following breast surgery, or tissue resections to remove tumors, or to restore function in aged livers by implanting a patch of functional liver tissue. The company has conducted a great deal of work to demonstrate that their tissue blocks are functional and stable over time, and match the strutural properties of native tissue as much as possible. They are presently conducting tests in animal models, and working towards partnerships with large pharma companies, which seems to be the standard approach for tissue engineering companies.

Matthew Scholz of Oisin Biotechnologies discussed their platform for genetic medicine based on LNP-mediated DNA delivery. At this point their first indications are sarcopenia and frailty, accumulation of unwanted fat, and accumulation of senescent cells. The company started with a focus on senescent cells, but that was not much discussed in this presentation, as Oisin obtained more support, funding, and interest for the other indications. The platform for delivery is the Entos Pharmaceuticals fusogenic LNPs, lipid nanoparticles that use a fusion protein derived from a virus to enable cell entry directly into the cytoplasm. This is distinct from the usual LNP path of endocytosis into a membrane-wrapped vesicle that must then be escaped to enter the cytoplasm. Fusogenic LNPs have no cell preference, and will enter any cell they encounter. This can be used as a starting point to build versions with some selectivity, but the unmodified LNP is the closest anyone has come to a vector that has broad body-wide distribution without the major organs taking up most of it. The company uses DNA machinery as a cargo for the LNP to engineer very selective expression of transgenes in specific tissues. The first application is to upregulate follistatin in to produce muscle growth. The team has demonstrated this outcome in mice, including in very old mice. The second application is to destroy unwanted fat cells, and the technology can selectively target specific fat pads via promoters that are only active in those tissues. They can also change the fusogenic LNP to more selectively target fat cells specifically. In effect the result is liposuction without surgery. In the future Oisin wants to broaden this technology platform to many other potential uses. The company is presently raising an A round led by Abbvie Ventures.

Jean Hebert of BE Therapeutics presented on tissue engineering for the brain. Permanent brain damage is a problem in many contexts, such as aging, injury, and cancer, and there is no approach at present to replace that tissue. The company is trying to develop a way to regrow brain tissue based on the recreation of developmental processes. Starting with the neocortex, the team analyzed precursor cells, and can now assemble an architecturally correct, vascularized neocortex organoid prototype from cell populations derived from induced pluripotent stem cells. The neocortex is a very dynamic part of the brain, with connections and usage changing constantly, so it seems possible to put in new tissue and have it be used appropriately to encode information. The team has implanted prototype tissues in mice, replacing a part of the neocortex that was surgically removed. They are now proceeding with work on human tissues, testing the function of developing neurons in preparation to optimize the form and function of the prototype tissues. The initially targeted indications involve damage to the neocortex, such as that resulting from stroke and dementia. The company is in the early preclinical stage, and has yet to conduct studies in animal models of those conditions.

Janine Sengstack of Junevity talked about the platform that she developed during her PhD, enabling discovery of transcription factors that alter cell behavior into more youthful phenotypes. Gene expression changes with age, the large number of individual changes can be mapped and measured, and thus one can screen and identify transcription factors that affect a large faction of this network of genes. The company uses siRNA to downregulate specific transcription factor expression, and have demonstrated proof of principle in vitro for liver cells. The treatment improved cell function along with resetting some of the map of changed gene expression. The team has used the platform to determine candidate transcription factors to suppress in the aging liver and fat tissue, and are working on skin aging as well. They are collaborating with a pharma company for target discovery in obesity. They have shown improved liver function, improved mitochondrial function, and lowered liver fat in obese mice using siRNA suppression of one transcription factor candidate. In skin, they have found a way to improve collagen production and restore more youthful gene expression across thousands of genes via siRNA suppression of a single transcription factor.

Joanna Bensz of Longevity Center Europe, Petr Sramek of the Healthy Longevity Clinic and and Elisabeth Roider of the AYUN Health & Longevity Center presented on their respective longevity clinics. The most interesting of these projects, the one that isn't just a provision of boutique medical services, is the Healthy Longevity Clinic. This group are trying something new, a fusion of investing in companies, giving those companies a path to clinical trials outside the US, and clinics to offer services that will eventually include new therapies created by portfolio companies. They have established a number of clinics, in Praque and Florida, with a subsidiary in the Bahamas set up to conduct clinical trials there. Medical development is slow, and so it will take some time to see whether this proves to be a viable and helpful approach in practice: it would require a sizable fraction of companies to step away from the present well-beaten and thus safe path with regulators.

A panel of investors discussed the industry: Jens Eckstein of the Hevolution Foundation; Jan Adams of Apollo Health Ventures; Sergey Jakimov of LongeVC; Marc P. Bernegger of the company builder maximon; Alex Colville of age1; Patrick Burgermeister of Kizoo Technology Capital. The group offered a considerable diversity of opinions on what is important in the field. A lesson to take away is that the natural size of a faction of investors is one investor; they are all quite different.

Jürgen Reeß of Mogling Bio talked on the development of new, recently patented CDC42 inhibitors based on CASIN, a molecule that has been used to demonstrate reversal of stem cell aging and improved immune function in mice. The team sees CASIN as having too low a bioavailability to be a viable drug, too much of it is needed per dose. The new CDC42 inhibitors have similar effects, but with lower doses. The team has shown that CDC42 inhibition with CASIN can slow tumor growth in mouse models to the same degree as a PD1 checkpoint inhibitor, and the data suggests that this is an immunomodulatory effect achieved via altered regulatory T cell behavior. If combining CASIN and a PD1 inhibitor, tumors shrink and vanish in a mouse model. Thus cancer will be the company's first indication. The company is working towards IND-enabling studies in 2025, and are meanwhile running a number of collaboration programs to broaden the set of possible indications with proof of concept data.

Aaron Cravens of Revel Pharmaceuticals put advanced glycation end-products (AGEs) such as carboxymethylysine (CML) and glucosepane cross-links into the contxt of a damage-based view of aging. Aging is accumulated molecule damage, and repairing that damage is rejuvenation. AGEs are known to contribute to many aspects of aging, and Revel develops a platform to discover enzymes that can break down specific AGEs. Going into detail on the present programs, CML exists in a free circulating form and a bound form in the extracellular matrix, both of which provoke inflammatory reactions. In the last few years the company has developed enzymes that are much more effective than the initial 2019 candidates when it comes to clearing free CML. Cravens sees success with free CML as a stepping stone to the harder task of success with bound CML in the extracellular matrix. The company has considered which AGEs offer the fastest to get to the clinic; while the Revel started with a focus on glucosepane, it is a harder prospect. CML is less challenging, and this is now an initial focus. In principle, an early success with CML will build momentum for further investment for work on the more challenging AGEs.

Aaron Friedman of Reservoir Neuroscience started his presentation by noting that aging is complex and brain aging is particularly complex. Yet the research and development mainstream has ignored this complexity in favor of a relentless focus on just a few things, as in the case of amyloid and Alzheimer's disease. He suggested that the evidence suggests that Alzheimer's is largely a lifestyle disease, and thus interventions derived from lifestyle factors can postpone or slow Alzheimer's. In particlar, people who exercise have a 45% reduction in Alzheimer's risk, somewhat better than the effects of current anti-amyloid antibody treatments. Additionally, imaging data shows that loss of vascular health is the largest factor contributing to Alzheimer's; vascular aging appears before the increase in amyloid burden, and is a larger and easier signal to detect. Thus the industry should be focused on treating poor vascular health. The company intends to develop drugs that target this vascular dysfunction, and has built a drug discovery platform using organ-on-a-chip screening in blood vessel organoids. The team is in the early stages of lead optimization for one candidate inhibitor of the prostaglandin E2 receptor 2 (EP2), which is upregulated in aged and damaged blood vessels. This is a master regulator of inflammatory responses, and so suppressing it effectively should reduce chronic inflammation. Friedman notes that the beneficial effect of long-term NSAID use (specifically ibuprofen in the study referenced) on Alzheimer's risk may be mediated by indirect inhibition of EP2.

Chris Bradley of MatterBio works on advanced sequencing. There are many genomes in the body, as every cell is a little different, genetically and epigenetically. Unrepaired DNA damage accumulates constantly. Most of this is neither good nor bad, it is just noise that increases with age. Researchers think that the greater the mutational burden, the bigger the impact on aging. Speed of mutation accumulation is correlated with species life span, and regardless of species life span every cell has 1000 to 5000 mutations in old age. One consequence of mutational damage is cancer. The MatterBio plan is to (a) read the DNA, (b) identify mutations, then (c) either reverse mutations directly or replace bad cells. The team has developed a novel approach to next generation sequencing in order to see single cell mutations; this is a commercial technology being sold now. They are designing DNA editing machinery that can fix a mutation, and this is still a very early stage project. Lastly, the team has engineered bacteria and markers that allow the destruction of mutated cells, and this is heading into to the clinic as a treatment for cancer. They have shown both pancreatic cancer and ovarian cancer reduction in metastatic preclinical mouse studies.

Nikolina Lauc of GlycanAge discussed the company's aging clock based on measures of changing glycan levels. Glycosylation is a posttranslational modification that produces glycans. Immunoglobulin G glycans are among those that change significantly with age. Few labs work with glycans, but this group has at this point generated more than 160,000 glycomes from human samples. Interestingly, glycan changes can indicate early signs of later chronic disease up to a decade in advance for many conditions, including hypertension and autoimmune conditions. The GlycanAge clock compares well with the best epigenetic clocks in predication power for mortality, but the accelerations are different for age measured by glycans versus age measured by epigenetic changes. A few interesting differences are noted: GlycanAge shows that metformin has no effect on aging, while professional athletes have poor GlycanAge measures in comparison to those who undertake only moderate exercise.

Sophie Chabloz of AVEA presented on their development of a collegen precursor for skin aging. This has all of the slick marketing appearance of a very standard skin anti-aging company at the less reputable end of the industry, but they do at least have an interesting scientific program under all of that cover. After noting the existing industry strategies for adding collagen to skin and diet, and the drawbacks, Chabloz discussed the company's development program. Work started in in C. elegans before moving to cell models of skin. The company has tested their collagen precursor in combination with alpha-ketoglutarate in C. elegans, showing a modest extension of life span.

The last panel of the conference was led by Nina Ruge, a science journalist and author. I was on that panel with (in no particular order) Eric Verdin of the Buck Institute, Brian Kennedy of the National University of Singapore, and Phil Newman of Longevity.Technology. We talked about longevity clinics and what they can offer to the industry; to my mind the most interesting thing that clinics can do for us all is to free up their data and help organize clinical trials. Ruge asked us our opinions on the most interesting part of the industry, and we all had radically different answers on that topic, just as we differed on where we would invest funds for the best outcome, given the power to do so. It is characteristic of the aging and longevity field that almost everyone is in their own group of one when it comes to what the next steps should be.

It remains to be seen as to when the next conference in this series will be held - probably in 2026. I recommend attending. This remains an event at the core of the longevity industry. Many of the most interesting presenting founders and attendees have been involved in some way since the start of this great endeavor. Many of the presentations offered a strong identification with the Strategies for Engineered Negligible Senescence (SENS) viewpoint of aging as accumulated cell and tissue damage, and thus damage repair is the way to treat aging. Consider adding the next Rejuvenation Startup Summit to your calendar when it is announced.

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Low Serum α-Klotho Correlates with Raised Risk of Age-Related Mortality

Klotho is one of the few longevity-associated genes shown to work in both directions; lower expression shortens life span in animal studies, while increased expression modestly slows aging. Despite several decades of research, scientists have yet to reach a full understanding of how klotho influences life span. The klotho gene produces a transmembrane protein that operates inside and on the surface of cells, as well as a section of the protein, α-klotho, that detaches to act as a signal molecule outside the cell. Study has primarily focused on the protective role of klotho in the kidneys, with the hypothesis that kidney function is important enough to organs throughout the body that slowed kidney aging has a global effect on healthspan. Since the discovery that increased circulating α-klotho improves cognitive function, even in younger animals, however, researchers have increasingly focused on how klotho might be slowing aging in the brain.

The study here is one of a number to examine human data in order to provide support for the ongoing development of therapies based on delivery of an optimized α-klotho version. Does the evidence in humans suggest that the broad base of animal study data will hold up in our species? Largely yes. Levels of α-klotho in blood can be measured, and those individuals with less circulating α-klotho appear to experience increased risk of age-related disease and mortality. At this point it seems likely that therapies to increase circulating α-klotho levels will emerge before a complete understanding of why it is that this increase is beneficial.

The prognostic value of serum α-klotho in age-related diseases among the US population: A prospective population-based cohort study

α-Klotho is a potential biological marker of aging with satisfactory clinical applicability. However, its prognostic significance in age-related diseases has largely been undermined. Therefore, we aimed to report the prognostic value of serum α-klotho levels in age-related diseases.

Participants with available serum α-klotho data from the National Health and Nutrition Examination Survey (2007-2016) were included. Their survival status was collected at 7.62 ± 2.99 years after serum α-klotho data was collected, and the endpoint was all-cause and cardiovascular mortality. A Cox regression model was established to examine the association between serum α-klotho levels and all-cause and cardiovascular mortality.

The present study included 13,746 U.S. adults with a survey-weighted mean age of 56.19 ± 10.42 years old. The optimal cutoff value of serum α-klotho for predicting all-cause mortality risk in the general population was 603.5 pg/ml. Individuals with low serum α-klotho (less than 603.5 pg/ml) had a significantly higher risk of all-cause (adjusted hazard ratio: 1.34) and cardiovascular mortality (adjusted hazard ratio: 1.63). Subgroup analysis showed that low serum α-klotho level was an independent risk factor for all-cause and cardiovascular mortality in people with hypertension, congestive heart failure, diabetes mellitus, and emphysema, while it was an independent risk factor for all-cause mortality in patients with renal insufficiency.

A low serum α-klotho concentration (less than 603.5 pg/ml) could serve as a marker of all-cause and cardiovascular mortality in the general population and in people with age-related diseases, including hypertension, congestive heart failure, diabetes mellitus, and emphysema.

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Investigating the Mechanisms by which Intermittent Fasting is Protective of the Liver

The various approaches to restricting calorie intake remain a popular area of scientific study, as periods of low calorie intake produce broadly beneficial effects on the operation of metabolism. They are protective when it comes to the effects of aging. In animal studies, life-long calorie restriction has been shown to slow aging and extend life span. A great deal of work has gone into the production of calorie restriction mimetic drugs that recreate a small fraction of the metabolic response to low calorie diets and fasting, but as of yet none of these are demonstrated to improve on the practice of calorie restriction.

In humans, the evidence suggests that health benefits resulting from even comparatively mild calorie restriction are sizable enough to make it worth considering as a lifestyle choice. That said, the effects on life span are clearly smaller in longer-lived species. Mice live up to 40% longer when calorie restricted, and that is not the case in humans. Exactly why this difference exists remains a mystery, particularly given that the short term metabolic changes that occur when calorie intake is reduced are broadly similar across mammalian species. As today's open access paper notes, when comparing the beneficial changes to the liver that result from calorie restriction, the biochemistry looks very similar in mice and humans.

Intermittent fasting protects against liver inflammation and liver cancer / Drug partially mimics fasting effects

When experimenting with different variants of intermittent fasting, it was found that several parameters determine protection against liver inflammation: The number and duration of fasting cycles play a role, as does the start of the fasting phase. A 5:2 dietary pattern works better than 6:1; 24-hour fasting phases better than 12-hour ones. A particularly unhealthy diet requires more frequent dieting cycles.

Researchers now wanted to find out the molecular background of the response to fasting. To this end, the researchers compared protein composition, metabolic pathways and gene activity in the liver of fasting and non-fasting mice. Two main players responsible for the protective fasting response emerged: the transcription factor PPARα and the enzyme PCK1. The two molecular players work together to increase the breakdown of fatty acids and gluconeogenesis and inhibit the build-up of fats.

The fact that these correlations are not just a mouse phenomenon was shown when tissue samples from metabolic dysfunction-associated steatohepatitis (MASH) patients were examined: Here, too, the researchers found the same molecular pattern with reduced PPARα and PCK1. Are PPARα and PCK1 actually responsible for the beneficial effects of fasting? When both proteins were genetically switched off simultaneously in the liver cells of the mice, intermittent fasting was unable to prevent either chronic inflammation or fibrosis.

The drug pemafibrate mimics the effects of PPARα in the cell. Can the substance also mimic the protective effect of fasting? The researchers investigated this question in mice. Pemafibrate induced some of the favorable metabolic changes that were observed with 5:2 fasting. However, it was only able to partially mimic the protective effects of fasting. "This is hardly surprising, as we can only influence one of the two key players with pemafibrate. Unfortunately, a drug that mimics the effects of PCK1 is not yet available."

A 5:2 intermittent fasting regimen ameliorates NASH and fibrosis and blunts HCC development via hepatic PPARα and PCK1

The role and molecular mechanisms of intermittent fasting (IF) in metabolic dysfunction-associated steatohepatitis (MASH) and its transition to hepatocellular carcinoma (HCC) are unknown. Here, we identified that an IF 5:2 regimen prevents NASH development as well as ameliorates established MASH and fibrosis without affecting total calorie intake. Furthermore, the IF 5:2 regimen blunted MASH-HCC transition when applied therapeutically. The timing, length, and number of fasting cycles as well as the type of NASH diet were critical parameters determining the benefits of fasting.

Combined proteome, transcriptome, and metabolome analyses identified that peroxisome-proliferator-activated receptor alpha (PPARα) and glucocorticoid-signaling-induced PCK1 act co-operatively as hepatic executors of the fasting response. In line with this, PPARα targets and PCK1 were reduced in human MASH. Notably, only fasting initiated during the active phase of mice robustly induced glucocorticoid signaling and free-fatty-acid-induced PPARα signaling. However, hepatocyte-specific glucocorticoid receptor deletion only partially abrogated the hepatic fasting response. In contrast, the combined knockdown of PPARα and Pck1 in vivo abolished the beneficial outcomes of fasting against inflammation and fibrosis. Moreover, overexpression of Pck1 alone or together with PPARα in vivo lowered hepatic triglycerides and steatosis. Our data support the notion that the IF 5:2 regimen is a promising intervention against MASH and subsequent liver cancer.

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Can Polyphenol Senotherapeutics be Improved with the Use of Nanocarriers?

If you've ever wondered why so much effort goes towards the development of supplements and other only marginally effective interventions based on the use of plant extracts, the answer is quite simple: it is usually far cheaper to gain regulatory approval for commercial sale via this approach. From the point of view of many developers, it doesn't much matter how good the result is, as sales in the supplement space are driven by marketing, not efficacy. Thus keep the costs low. So much of this industry is trapped in a cycle in which the search for the lowest regulatory cost produces a market packed with marginal interventions, where competition is driven by branding and marketing rather than product efficacy, and that in turn educates developers and consumers to work towards more of the same.

That said, there are a few plant extracts that might actually be useful enough to pay attention to. Clearance of senescent cells in aged tissues is an important goal, as these cells actively harm tissue function and promote chronic inflammation. A few plant extracts appear to be able to selectively kill senescent cells, most notably piperlongumine and fisetin when used on their own. Quercetin is more widely known, but only because it is a part of the well studied dasatinib and quercetin combination; on its own quercetin isn't meaningfully senolytic. For piperlongumine and fisetin there is an absence of published human data (despite the existence of a clinical trial in the case of fisetin).

Still, all of these compounds are comparatively poorly bioavailable, which has led to groups attempting formulations with varieties of nanocarrier, such as encapsulation in liposomes, that will enable better distribution into the desired target cells. Time will tell as to whether this is a useful line of research and development that will lead to senolytic therapies that are both cheaper and comparably effective to the more sophisticated therapies under development in the longevity industry.

Nanocarriers for natural polyphenol senotherapeutics

Senescence is a heterogenous and dynamic process in which various cell types undergo cell-cycle arrest due to cellular stressors. While senescence has been implicated in aging and many human pathologies, therapeutic interventions remain inadequate due to the absence of a comprehensive set of biomarkers in a context-dependent manner. Polyphenols have been investigated as senotherapeutics in both preclinical and clinical settings. However, their use is hindered by limited stability, toxicity, modest bioavailability, and often inadequate concentration at target sites.

To address these limitations, nanocarriers such as polymer nanoparticles and lipid vesicles can be utilized to enhance the efficacy of senolytic polyphenols. Focusing on widely studied senolytic agents - specifically fisetin, quercetin, and resveratrol - we provide concise summaries of their physical and chemical properties, along with an overview of preclinical and clinical findings. We also highlight common signaling pathways and potential toxicities associated with these agents. Addressing challenges linked to nanocarriers, we present examples of senotherapeutic delivery to various cell types, both with and without nanocarriers. Finally, continued research and development of senolytic agents and nanocarriers are encouraged to reduce the undesirable effects of senescence on different cell types and organs.

This review underscores the need for establishing reliable sets of senescence biomarkers that could assist in evaluating the effectiveness of current and future senotherapeutic candidates and nanocarriers.

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Revisiting the Pace of Aging Biomarker

The Pace of Aging biomarker emerged from analysis of the Dunedin Study data. It is analogous to epigenetic clocks or phenotypic age, in that it is produced by a machine learning approach, working backwards from a large database of parameters and their changes with age in the study population. Instead of being an assessment of biological age, however, it is an assessment of the pace of biological aging.

In today's open access paper, the Pace of Aging developers improve on their original design. They expand the study populations used and reduce the number of individual assays needed to construct the Pace of Aging marker. They also show correlations between Pace of Aging and aspects of aging such as life expectancy, mortality risk, and risk of developing age-related disease. Interestingly, Pace of Aging increases with advancing age, much as one might expect given the way in which age-related loss of function is observed to progress.

Pace of Aging in older adults matters for healthspan and lifespan

Our original Pace of Aging method was developed from analysis of health changes from young adulthood to midlife in the Dunedin Study 1972-73 birth cohort. To be most useful for comparative biodemographic analysis used by planners to evaluate efforts to promote healthy longevity, the Pace of Aging method needs to be adapted to a different context: samples of individuals representing a wide range of birth cohorts for whom follow-up begins later in the life course. In addition, whereas the Dunedin Study collected extensive biochemical and physical examination data from participants, the studies used by planners typically have access to much sparser measurement panels. Here, we introduce an adapted method for calculation of Pace of Aging in a sample composed of a wide range of birth cohorts with follow-up in midlife and older age and a sparse panel of biomarkers.

We compiled data from dried-blood spot, physical exam, and functional test protocols conducted by the US Health and Retirement Study (HRS) during 2006-2016 (six assessment waves). We identified nine parameters measured at all six waves that met criteria for inclusion in the Pace of Aging analysis: C-reactive protein (CRP), Cystatin-C, glycated hemoglobin (HbA1C), diastolic blood pressure, waist circumference, lung capacity (peak flow), tandem balance, grip strength, and gait speed. A total of 13,626 individuals provided data on at least six of these nine biomarkers across at least two of the follow-up assessments. We modeled longitudinal change in these biomarkers to estimate person-specific slopes for each of them. Then we combined slope information across biomarkers to compute each participants' Pace of Aging.

The adapted Pace of Aging measure reveals stark differences in rates of aging between population subgroups and demonstrates strong and consistent prospective associations with incident morbidity, disability, and mortality. Pace of Aging accelerates at more advanced ages. HRS participants who were older at their baseline biomarker assessment showed more rapid change across subsequent follow-ups as compared to those who were younger. This observation is consistent with biodemographic data showing that mortality risk accelerates at older ages. Pace of Aging is faster in sociodemographic groups characterized by shorter lifespan. Men tended to experience faster Pace of Aging as compared with women. Those with less education tended to experience faster Pace of Aging as compared to those with more education, consistent with observations of a socioeconomic gradient in the pace of aging from the Dunedin Cohort and a Swiss cohort.

Midlife and older adults with faster Pace of Aging were at increased risk of incident chronic disease, disability, and mortality. Older adults with faster Pace of Aging more often developed new chronic diseases and disabilities and were at increased risk of death. Moreover, these associations were independent of smoking, obesity, and educational attainment.

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Reviewing the Role of Neuroinflammation in Neurodegenerative Disease

Unresolved, constant inflammatory signaling is a feature of aging, the consequence of accumulated senescent cells and other maladaptive reactions to various forms of molecular damage and cellular dysfunction. This inflammation drives the onset and progression of many age-related conditions, particularly neurodegenerative diseases. The immune system is deeply integrated with the structure, function, and maintenance of neural tissue, and the age-related shift into a constant inflammatory state is increasingly disruptive to normal brain function.

Neuroinflammation refers to a highly complicated reaction of the central nervous system (CNS) to certain stimuli such as trauma, infection, and neurodegenerative diseases. This is a cellular immune response whereby glial cells are activated, inflammatory mediators are liberated and reactive oxygen species and reactive nitrogen species are synthesized. Neuroinflammation is a key process that helps protect the brain from pathogens, but inappropriate, or protracted inflammation yields pathological states such as Parkinson's disease, Alzheimer's, Multiple Sclerosis, and other neurodegenerative disorders that showcase various pathways of neurodegeneration distributed in various parts of the CNS.

This review reveals the major neuroinflammatory signaling pathways associated with neurodegeneration. Additionally, it explores promising therapeutic avenues, such as stem cell therapy, genetic intervention, and nanoparticles, aiming to regulate neuroinflammation and potentially impede or decelerate the advancement of these conditions. A comprehensive understanding of the intricate connection between neuroinflammation and these diseases is pivotal for the development of future treatment strategies that can alleviate the burden imposed by these devastating disorders.

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Organ Bioprinting as the Pinnacle of Tissue Engineering

This article serves as a high level overview of the present state of bioprinting of three-dimensional sections of living tissue. The field has stalled at the hurdle of vascularization for more than a decade now; it has proven to be challenging to make the leap from tiny functional organoid tissues to something larger. It isn't just the matter of building in capillary and larger blood vessel networks, however. Organoids are largely only approximations to real structured tissue, good enough to be functional in many respects, but not the final goal. In order to build sizable sections of organs with bioprinters, a great deal of work remains in order to be able to create structures that more closely, usefully match those of the body, even given that many of the pieces of that puzzle already exist.

Bioprinting is still in its infancy and bogged down by various challenges related to different aspects of the bioprinting process. The primary challenge is developing an ideal bioink that is apt for the tissue of interest to be printed. Maintaining adequate cell density and viability following extrusion, obtaining air bubble-free extruded filaments, achieving adequate mechanical strength post-printing, achieving vascularization and innervation of the tissue constructs, and printing complete organs are the major challenges slowing down the bioprinting process. Research is being conducted to overcome these hurdles and provide personalized treatment solutions for regenerating the lost tissues.

Gaining in-depth knowledge regarding the organogenesis process, the tissue structure, composition, and behavior of each tissue, ways to maintain cell viability, and tissue integration with the native tissue post-printing would enable us to overcome these challenges one step at a time. 4D bioprinting has recently emerged, where time is considered the fourth dimension of printing. The printed scaffold modulates their organization and behavior according to time-dependent external stimuli. The future is moving toward five-dimensional (5D) printing, which will occur in multiple rotational axes.

Advanced bioprinting technologies would greatly reduce the demand for organ donations. Government organizations and regulators are still working toward achieving a balance between the need for organ donation through early prevention and management of diseases and improved procurement of organs. Application of bioprinting technologies would greatly reduce the burden on the governments and buy us time till every nation becomes self-sufficient to manage the need for organ donations. Though the setting up of a bioprinting center of excellence is a costly affair, in terms of obtaining the infrastructural and biologics support, the number of lives saved through its applications in regenerative and rehabilitative medicine is of paramount significance.

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Bacterial Peptide Inhibits Aggregation of α-Synuclein

Researchers here report on continued investigation of a bacterial peptide capable of disrupting misfolded α-synuclein aggregation. This aggregation is the driving pathology of Parkinson's disease. In other cases, such as for transthyretin amyloid, it has been possible to design small molecule drugs that interfere in harmful protein aggregation. While the bacterial peptide is toxic to cells, it is hoped that better understanding its interaction with α-synuclein will lead to non-toxic small molecules that can achieve the same disruption of protein aggregation, and thus a viable treatment for Parkinson's disease and other synucleinopathies.

Alpha-synuclein aggregation is a hallmark of Parkinson's disease and other synucleinopathies. It is a dynamic process in which the protein self-assembles to form oligomers that eventually develop toxic amyloid fibrils, which accumulate in the patient's brain. Alpha-synuclein oligomers play a key role in the development and progression of the disease and, therefore, are promising therapeutic and diagnostic targets, particularly in the early stages of the disease, but their transient and highly dynamic nature limits the study of their structure and hinders the development of therapies aimed at blocking them.

Researchers had observed in a previous study that a small molecule, the bacterial peptide PSMα3, inhibited the aggregation of alpha-synuclein in binding to oligomers, blocking the conversion to fibrils and inhibiting neurotoxicity. In this study, they identified where, how and when this binding occurs in the oligomers, uncovering a key region for the structural conversion process associated with the pathogenesis of Parkinson's disease. Researchers observed that PSMα3 acts by binding to one end of the alpha-synuclein (N-terminus) that regulates the oligomer-to-fibril conversion process. Upon binding, the peptide covers two small adjacent regions of the protein which have been found to be critical for this pathogenic transition.

"We identified the structure's sequence that is essential for the conversion of oligomers to fibrils, thus opening a new field of exploration in the design of molecules aimed at targeting oligomers. By leveraging this region, we can develop new molecules that mimic the properties of PSMα3 with a much higher affinity and efficacy."

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Bile Acid Metabolism Correlates with Cognitive Impairment

Researchers here show that bile acid metabolism makes a meaningful contribution to age-related neurodegeneration and cognitive decline. Bile acids produced by the gut microbiome leave the intestines in growing amounts with advancing age, and cause harm to the brain. In animal models, the researchers demonstrate a that sequestering bile acids in the intestine with suitable molecules can reduce the bile acid contribution to brain aging. It is plausible that adjusting the balance of populations in the aged gut microbiome via fecal microbiota transplant from a young individual could produce similar benefits, but that has yet to be rigorously assessed.

Recent studies have suggested a link between changes in bile acids (BAs) and age-related cognitive impairment. Investigations into Alzheimer's disease and Parkinson's disease reveal that lower serum levels of unconjugated primary BAs (UPBAs), such as cholic acid and chenodeoxycholic acid, along with elevated levels of glycochenodeoxycholic acid, a conjugated primary BA metabolite, are closely associated with the severity of cognitive decline symptoms.

Current understanding suggests that the gut microbiota, which produces secondary BAs in the gastrointestinal lumen, undergoes age-related alterations. These changes significantly impact the levels of BAs circulating in the body and present within the brain. Additionally, there is a notable correlation between certain serum BA metabolites, particularly increased levels of glycolithocholic acid and tauro-lithocholic acid, which are bacterially derived secondary BAs, and elevated cerebrospinal fluid total tau levels. BAs can communicate between the periphery and the brain either through specific BA transporters or by passive diffusion across the blood-brain barrier.

In this study, we observe elevated levels of serum conjugated primary bile acids (CPBAs) and ammonia in elderly individuals, mild cognitive impairment, Alzheimer's disease, and aging rodents, with a more pronounced change in females. These changes are correlated with increased expression of the ileal apical sodium-bile acid transporter (ASBT), hippocampal synapse loss, and elevated brain CPBA and ammonia levels in rodents. In vitro experiments confirm that a CPBA, taurocholic acid, and ammonia induced synaptic loss. Manipulating intestinal BA transport using ASBT activators or inhibitors demonstrates the impact on brain CPBA and ammonia levels as well as cognitive decline in rodents. Additionally, administration of an intestinal BA sequestrant, cholestyramine, alleviates cognitive impairment, normalizing CPBAs and ammonia in aging mice.

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Aging T Cells May Promote Pathological Changes in Tissue Structure

The immune system is complex and undertakes many activities in the body beyond mounting a defense against pathogens. Immune cells are involved in many of the normal processes of tissue maintenance. Even where there is no direct involvement, the secreted signals produced by inflammatory immune cells produce changes in the behavior of other cell populations. Thus we should not be surprised to find it possible to draw connections between the state of the immune system and the structural properties of tissue that arise from the behavior of the cells making up that tissue. This is one of many reasons why change and dysfunction in the immune system is an important component of aging, and one that should be addressed as a part of any broad attempt to produce rejuvenation.

It is well known that during the aging process, the immune system changes, that is, the disorder and decline of immune system function. In the aging state, the immune system usually shows a relatively continuous state of low activation. When stimulated by the outside world, its dynamic response becomes weaker and the amplitude is reduced, and this combination of chronic inflammatory state and reduced effective defense ability is often referred to as immune aging.

Studies have found that immune aging is associated with increased morbidity and mortality in the elderly. With the increase of age, T cells with aging phenotypes will continue to accumulate, further promoting immune aging, resulting in a decrease in immune function and an increase in pro-inflammatory function.

It has been found that aging T cells may promote pathological changes in the tissue structure of various systems of the human body through a variety of mechanisms, thereby leading to related diseases and fundamentally affecting the health of the elderly. First, aging T cells continue to produce cytokines that directly promote inflammation. Secondly, aging T cells may not be able to perform the function of monitoring aging, so that they cannot clear the irreversibly damaged cells that become senescent cells. In addition, aging T cells can lead to the loss of autoimmune tolerance and secrete cytotoxic substances that directly damage tissues. Finally, aging T cells can also indirectly participate in various changes by regulating intestinal homeostasis.

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Reversing Immune Aging is an Important Goal

The immune system declines with age, becoming both less effective (immunosenescence) and at the same time overly inflammatory and active (inflammaging). It isn't just less effective when it comes to defending against infectious pathogens, but also in the matter of destroying senescent and potentially cancerous cells. Meanwhile, constant unresolved inflammatory signaling is disruptive to tissue structure and function, altering cell behavior for the worse. There are many possible approaches to at least somewhat reverse the underlying causes of these age-related dysfunctions of the immune system: restoring active thymic tissue; improving hematopoietic function; clearing malfunctioning and senescent immune cells; and so forth. More effort should be devoted to bringing these potential therapies to the clinic.

A stem-cell researchers didn't trust what they were seeing. Their elderly laboratory mice were starting to look younger. They were more sprightly and their coats were sleeker. Yet all the researchers had done was to briefly treat them - many weeks earlier - with a drug that corrected the organization of proteins inside a type of stem cell. In two papers, in 2020 and 2022, the team described how the approach extends the lifespan of mice and keeps them fit into old age. The target of this elixir is the immune system. The stem cells she treated are called haematopoietic, or blood, stem cells (HS cells), which give rise to all immune cells. As blood circulates, the mix of cells pervades every organ, affecting all bodily functions.

But the molecular composition of the HS cells changes with age, and this distorts the balance of immune cells that they produce. Recently another team showed that restoring the balance between two key types of immune cell gives old mice more youthful immune systems, improving the animals' ability to respond to vaccines and to stave off viral infections. Other scientists have used different experimental approaches to draw the same conclusion: rejuvenating the immune system rejuvenates many organs in an animal's body, at least in mice. And, most intriguingly, evidence suggests that immune system ageing might actually drive the ageing of those organs.

The potential - helping people to remain healthy in their later years - is seductive. But translating this knowledge into the clinic will be challenging. Interfering with the highly complex immune system can be perilous, researchers warn. So, at first, pioneers are setting their sights on important yet low-risk goals such as improving older people's responses to vaccinations and improving the efficiency of cancer immunotherapies. "The prospect that reversing immune ageing may control age-related diseases is enticing. But we are moving forward cautiously."

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Cellular Senescence in the Aging Kidney

Much of past research into age-related disease involves looking at changes in gene expression in the diseased organ, a very low-level laundry list of alterations. This is somewhat decoupled from the approach of looking at changes in cell behavior, a high-level laundry list of alterations. A sizable fraction of life science research involves trying to make firm connections between these two sets of data, to better steer development efforts towards interfering in more relevant rather than less relevant mechanisms. Here, as an example of this sort of work, researchers link PAR2 expression in the kidney to cellular senescence in that organ. Senescent cells accumulate with age to produce chronic inflammation and other tissue dysfunction. There is considerable interest in finding ways to both selectively remove these cells, or prevent their creation in the first place.

Cellular senescence contributes to inflammatory kidney disease via the secretion of inflammatory and profibrotic factors. Protease-activating receptor 2 (PAR2) is a key regulator of inflammation in kidney diseases. However, the relationship between PAR2 and cellular senescence in kidney disease has not yet been described. In this study, we found that PAR2-mediated metabolic changes in renal tubular epithelial cells induced cellular senescence and increased inflammatory responses.

Using an aging and renal injury model, PAR2 expression was shown to be associated with cellular senescence. Under in vitro conditions in a kidney epithelial cell line, PAR2 activation induces tubular epithelial cell senescence and senescent cells showed defective fatty acid oxidation (FAO). Cpt1α inhibition showed similar senescent phenotype in the cells, implicating the important role of defective FAO in senescence. Finally, we subjected mice lacking PAR2 to aging and renal injury. PAR2-deficient kidneys are protected from adenine- and cisplatin-induced renal fibrosis and injury, respectively, by reducing senescence and inflammation. Moreover, kidneys lacking PAR2 exhibited reduced numbers of senescent cells and inflammation during aging.

These findings offer fresh insights into the mechanisms underlying renal senescence and indicate that targeting PAR2 or FAO may be a promising therapeutic approach for managing kidney injury.

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The Contribution of Adaptive Immune System Aging to Atherosclerosis

Atherosclerosis is the buildup of fatty plaques in blood vessel walls that narrow and weaken those vessels, leading to rupture and a heart attack or stroke. While it is the innate immune cells known as macrophages that are responsible for removing excess lipids from blood vessel walls, clearing up the damage that leads to atherosclerotic plaques, atherosclerosis is a broadly inflammatory condition. Any contribution to systemic inflammatory signaling makes it harder for macrophages to do their job, and the aged adaptive immune system is just as much a source of inflammation as the aged innate immune system.

Whereas initiation of atherosclerotic plaques often occurs upon damage to the endothelium and subsequent infiltration of lipids into the vessel wall, its progression is marked by the infiltration of immune components leading to chronic inflammation of the plaque. Over time, the formation of necrotic debris, plaque destabilization and eventual rupture drive potentially fatal acute cardiovascular events such as a myocardial infarction or stroke. In light of the gradual functional decline of the aging immune system, it comes as no surprise that the incidence of acute cardiovascular events also greatly increases with age, even though atherosclerotic vascular changes already start occurring during early adolescence.

The hallmark feature of atherosclerotic plaque initiation is considered to be the accumulation of low density lipoproteins (LDL) in the tunica intima. This can occur due to a "leaky" endothelial cell layer of the vessel wall in response to damage, for example at sites of shear stress. Modification of LDL, primarily oxidation (oxLDL), promotes the recruitment and infiltration of monocytes into the vessel wall, and the subsequent accumulation of cholesterol-enriched foam cells that contribute to plaque growth and necrotic core formation. Adaptive immune responses, carried out by T cells and B cells, play a crucial role in atherosclerosis progression.

Distinct subsets of T cells, both effector memory T cells and regulatory T cells (Tregs), influence plaque development and stability. Notably, interferon gamma (IFNγ) secreting T helper (Th) 1 cells are the most common T cells found in atherosclerotic plaques. Th1 cells are considered pro-atherogenic, partially due to their role in stimulating macrophage polarization towards pro-inflammatory M1 effector cells. Advances in single cell technology further support the importance of adaptive immunity in atherosclerosis and revealed T-cells to be the most abundant leukocyte present in human carotid atherosclerotic plaques, outnumbering myeloid populations. Additionally, T cell receptor (TCR) sequencing has exposed plaque specific clonal expansion of CD4+ effector T cells with transcriptome profiles indicative of recent antigen-mediated T cell activation, thus suggesting an autoimmune component in atherosclerosis pathology.

Aging not only induces the expansion of pro-inflammatory and cytotoxic T cell subsets, but also stimulates an increase in T cells with regulatory phenotypes. An overall increase of Tregs was observed in the atherosclerotic aorta of aged LDLR knockout mice alongside a heightened expression of functional Treg markers and genes encoding for the IL-35 cytokine as compared to young mice. Similar upregulation of genes indicative of Treg activity was demonstrated in ex vivo human plaques. Moreover, Tregs show clonal expansion in the human carotid plaque. Previously, it has been reported that Treg functionality can decrease upon aging. Whether aging also impacts the immunosuppressive capacity of Tregs in the atherosclerotic environment, remains to be elucidated.

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Immune Cell Differences Must Be Considered in Epigenetic Age

Epigenetic age is most commonly measured via blood sample, assessing the epigenetic markers of immune cells in that sample. Unfortunately the present mainstream epigenetic clocks will provide different ages for different immune cell populations. This leads to meaningful variation in assessments of the same individual, because different cell populations might be present in somewhat different proportions in each blood sample. We might also question which of the cell populations provide the most useful epigenetic age when it comes to responsiveness to interventions that might slow or reverse aspects of aging. This is a well known problem at this point in the continued development of epigenetic clocks, but there is as yet little consensus on what to do about it.

Aging is a significant risk factor for various human disorders, and DNA methylation clocks have emerged as powerful tools for estimating biological age and predicting health-related outcomes. Methylation data from blood DNA has been a focus of more recently developed DNA methylation clocks. However, the impact of immune cell composition on epigenetic age acceleration (EAA) remains unclear as only some clocks incorporate partial cell type composition information when analyzing EAA.

We investigated associations of 12 immune cell types measured by cell-type deconvolution with EAA predicted by six widely-used DNA methylation clocks in data from more than 10,000 blood samples. We observed significant associations of immune cell composition with EAA for all six clocks tested. Across the clocks, nine or more of the 12 cell types tested exhibited significant associations with EAA. Higher memory lymphocyte subtype proportions were associated with increased EAA, and naïve lymphocyte subtypes were associated with decreased EAA. To demonstrate the potential confounding of EAA by immune cell composition, we applied EAA in rheumatoid arthritis.

Our research maps immune cell type contributions to EAA in human blood and offers opportunities to adjust for immune cell composition in EAA studies to a significantly more granular level. Understanding associations of EAA with immune profiles has implications for the interpretation of epigenetic age and its relevance in aging and disease research.

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Epigenetic Change with Age in Mice is Not Linear

Epigenetic marks such as DNA methylation control expression of genes and cell behavior. They change with age, a reflection of the processes of damage and dysfunction that occur with age. Researchers here focus on DNA methylation in one organ in mice to demonstrate that age-related changes are not linear over time. The individual goes through stages and phase transitions from one state of cellular behavior to another. This is worth considering when thinking about how epigenetic clocks that measure biological age might work in practice, especially when used as a way to evaluate the efficacy of potential rejuvenation therapies.

Analyzing the data of aging mouse colon tissues, we have identified multiple sets of CpG sites exhibiting sudden methylation changes at two different time points. One group of sets undergoes a rapid methylation change during the early-to-midlife transition, while another group exhibits accelerated methylation changes during the mid-to-late-life transition. Interestingly, DNA methylation switches at similar time points were observed in rat peripheral blood DNA. Notably, the division of the lifespan into three stages is already supported by the raw methylation data.

Our data goes in line with a digital aging hypothesis which views aging as a process consisting of discrete steps resulting from mechanisms showing variation in rate during lifespan. The existence of transitions between discrete stages reveals the more controlled, or even programmed, nature of epigenetic aging and opens questions about the regulation and consequences of these abrupt changes. It also indicates that essential insights into the nature of aging may be missed when comparing only two ages.

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