Fight Aging!

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.

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.

Link: https://doi.org/10.3389/fimmu.2024.1350471

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.

Link: https://doi.org/10.1111/acel.14184

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.

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."

Link: https://doi.org/10.1038/d41586-024-01274-3

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.

Link: https://doi.org/10.1186/s12979-024-00433-4

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.

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.

Link: https://doi.org/10.1016/j.xcrm.2024.101543

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."

Link: https://www.uab.cat/web/newsroom/news-detail/therapeutic-target-identified-to-neutralise-toxic-forms-of-parkinson-s-associated-protein-1345830290613.html?detid=1345915929138

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 Lifespan.io gave, I'm told, an interesting presentation, particularly given that SENS Research Foundation and Lifespan.io 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 LongevityTech.fund 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.

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.

Link: https://doi.org/10.7759/cureus.58029

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.

Link: https://doi.org/10.3389/fnagi.2024.1347987

Intravenous, high-dose AAV gene therapy to upregulate VEGF has been shown to extend life in mice. This is perhaps a demonstration of the importance of loss of capillary density in tissue as a result of age-related disruption to angiogenesis, the multi-step process by which new blood vessels branch from existing vessels. Upregulation of VEGF is one of the possible approaches to restoring maintenance of capillary networks via improved angiogenesis, as VEGF is one of the important signal molecules involved in this process.

A similar AAV gene therapy is being assessed in clinical trials for the treatment of coronary artery disease, the progressive blockage of blood flow to heart tissue by atherosclerotic plaque. Preliminary results were recently announced for the EXACT phase II trial. The idea here is to incrementally improve blood flow by encouraging the body to produce alternative paths. The therapy is locally delivered to heart tissue, and thus uses a much lower dose than would be needed for intravenous injection for delivery to much of the body. Nonetheless, the principle is much the same. One could argue that all older individuals would likely benefit from some form of VEGF upregulation delivered to much of the body.

Gene therapy treatment increasing body's signal for new blood vessel growth shows promise

Final 12-month data from the EXACT trial demonstrates safety and efficacy results for a vascular endothelial growth factor (VEGF) gene therapy treatment for patients who have advanced coronary artery disease (CAD). CAD, also known as coronary heart disease or ischemic heart disease, affects about 20.5 million U.S. adults - making it the most common type of heart disease in the United States. Often, the first sign of CAD is a heart attack, triggered by a rupture of plaque accumulated in the arteries supplying blood to the heart. Over time, plaque narrows these arteries, blood flow diminishes, leading to angina - a condition characterized by chest pain due to insufficient oxygen-rich blood supply to the heart muscle. In patients with the most severe form, angina can be disabling, and additional medications, procedures or surgery may not be effective. There is a need for therapies for such a serious condition.

The EXACT trial assesses the safety and preliminary efficacy of the gene therapy XC001 in patients with "no option" refractory angina (NORA). The gene vector is designed to more effectively and safely increase the body's own signal for new blood vessel growth. Effectiveness was measured primarily by exercise capacity, degree of impairment of blood flow to the heart, and angina frequency and severity. Among the 32 patients with NORA, the gene therapy XC001 appeared safe with no serious adverse effects due to the drug. Surgical delivery was generally well-tolerated. Early benefits of XC001 are promising in relation to improvements in exercise duration, decreased symptoms, and improved blood flow in patients' hearts.

Total exercise duration increased from a mean of 359.9 seconds at baseline to 448.2 at three months, 449.2 at six months, and 477.6 at 12 months. Total myocardial perfusion deficit on positron emission tomography imaging decreased by 10.2% at three months, 14.3% at six months, and 10.2% at 12 months - demonstrating a reduction in impaired blood flood. The time to onset of ST depression during exercise tolerance testing increased by 105.2 at three months, 113.6 at six months, and 103.1 seconds at 12 months. Angina frequency decreased by -7.7 at three months, -6.6 at six months, and -8.8 episodes at 12 months. Angina class improved in 81% of participants at six months.

Being more physically fit at a given age reliably correlates with a lower future mortality risk. While human epidemiological data can only provide correlations, animal studies can and do provide evidence for physical fitness and exercise to modestly slow aspects of aging and reduce age-related mortality. In general, maintaining physical fitness into later life appears to be a good idea, based on the evidence.

Cardiorespiratory fitness (CRF) is a physical trait that reflects the integrated function of numerous bodily systems to deliver and use oxygen to support muscle activity during sustained, rhythmic, whole-body, large muscle physical activity. CRF can be objectively measured using direct (usually by maximal exercise testing with concomitant gas exchange analysis) or indirect (exercise predicted equations) methods with a variety of maximal or submaximal protocols.

Low CRF is considered a strong chronic disease risk factor that is not routinely assessed in clinical practice. Evidence suggests that the inclusion of CRF as a clinical vital sign would enhance patient management by improving the classification of those at high risk of adverse outcomes. The evidence supporting CRF as an important risk factor has accumulated since the 1980s through large cohort studies that investigated the prospective risk of all-cause mortality and cardiovascular events associated with CRF. Research has linked CRF to the incidence of some cancers, type 2 diabetes, metabolic syndrome, stroke, and depression. Higher CRF may even improve the prognosis in those with chronic conditions such as cancer, peripheral artery disease, heart failure, and chronic kidney disease.

The objective of this study was to conduct an overview of systematic reviews with meta-analyses from cohort studies that investigated relationships between CRF and prospective health-related outcomes among adults. We identified 26 systematic reviews with meta-analysis representing over 20.9 million observations from 199 unique cohort studies. CRF had the largest risk reduction for all-cause mortality when comparing high versus low CRF (hazard ratio, HR=0.47). A dose-response relationship for every 1-metabolic equivalent of task (MET) higher level of CRF was associated with a 11%-17% reduction in all-cause mortality (HR=0.89). The certainty of the evidence across all studies ranged from very low-to-moderate according to Grading of Recommendations, Assessment, Development and Evaluations.

Link: https://doi.org/10.1136/bjsports-2023-107849

Researchers here present an interesting view of age-related circadian dysfunction, focusing on mismatched regulation between the central circadian clock and somewhat independent peripheral clocks. The regulation of circadian rhythm in tissues results from the activities of these complex systems of multiple parts - and like all complex systems they begin to exhibit dysfunction with advancing age. The novel aspect of this research is the concept of multiple mismatched circadian regulators as a cause of further dysfunction in tissues.

Discovered in the 1970s, circadian clocks are essential for the regulation of biological time in most cells in the human body. These internal mechanisms adjust biological processes to a 24-hour cycle, allowing the synchronisation of cellular functions with daily variations in the environment. Circadian rhythms, which are coordinated by a central clock in the brain that communicates with clocks in different peripheral tissues, influence many functions, from our sleep patterns to our ability to metabolise food.

A study on the communication between the brain and muscle confirmed that the coordination between the central and peripheral clocks is crucial for maintaining daily muscle function and preventing the premature ageing of this tissue. Restoration of the circadian rhythm reduces the loss of muscle mass and strength, thereby improving deteriorated motor functions in experimental mouse models.

The results of the study have also demonstrated that time-restricted feeding (TRF), which involves eating only in the active phase of the day, can partially replace the central clock and enhance the autonomy of the muscle clock. More relevant still is that this restoration of the circadian rhythm through TRF can mitigate muscle loss, the deterioration of metabolic and motor functions, and the loss of muscle strength in aged mice.

"It is fascinating to see how synchronisation between the brain and peripheral circadian clocks plays a critical role in skin and muscle health, while peripheral clocks alone are autonomous in carrying out the most basic tissue functions. Our study reveals that minimal interaction between only two tissue clocks (one central and the other peripheral) is needed to maintain optimal functioning of tissues like muscles and skin and to avoid their deterioration and ageing. Now, the next step is to identify the signalling factors involved in this interaction, with potential therapeutic applications in mind."

Link: https://www.irbbarcelona.org/en/news/scientific/synchronisation-between-central-circadian-clock-and-circadian-clocks-tissues

Transposable elements in the genome are the remnants of ancient viral infections, capable of hijacking cellular machinery to copy themselves haphazardly across the genome, causing damage to existing genes. They can further provoke inflammation and cell dysfunction via the presence of the viral machinery that these transposable element sequences code for; innate immune mechanisms in cells have evolved to detect such apparently foreign molecules. Transposable elements are effectively suppressed in youth, but with age this suppression breaks down. It has been suggested that activation of transposable elements is an important contributing factor in age-related conditions, particularly in neurodegenerative conditions such as Alzheimer's disease.

As today's open access paper notes, one way to obtain evidence for this proposition is to look at the long term outcome of antiretroviral drug use. These drugs are used to treat patients and animals infected with retroviruses, most prominently HIV, but also a number of others. In additional to suppressing infectious retroviruses, antiretroviral drugs also suppress the activity of transposable elements. After thirty years of a strong focus on treating AIDS, there is now a sizable patient population in later life, at the point at which transposable elements would be expected to become active.

Nucleoside Reverse Transcriptase Inhibitor Exposure Is Associated with Lower Alzheimer's Disease Risk: A Retrospective Cohort Proof-of-Concept Study

Alzheimer's disease (AD) is the most common form of dementia, affecting an estimated 6.5 million Americans including more than 10% of Americans over 65 years of age. There are no therapies that demonstrably stop the disease despite hundreds of clinical trials. The recent identification of reverse transcriptase (RT)-mediated somatic gene recombination (SGR) in the human brain, which becomes dysregulated in sporadic AD, implicates FDA-approved reverse transcriptase inhibitors (RTIs) as potential therapeutics for AD.

Multiple FDA-approved RTIs, the first of which was approved in 1987, are currently used to treat human immunodeficiency virus (HIV) and hepatitis B. RTIs can be orthosteric (bind to the active site) nucleoside RTIs (NRTIs) or allosteric non-NRTIs (NNRTIs), and together with integrase inhibitors and protease inhibitors (PIs), represent the components of combined antiretroviral therapy (cART). Because of effective cART, tens of thousands of people with HIV have lived to older ages but are now at risk for AD, providing an opportunity to retrospectively examine the incidence of AD by assessing medical claims databases.

This retrospective, proof-of-concept study evaluated the incidence of AD in people with HIV with or without exposure to NRTIs using de-identified medical claims data. Eligible participants were aged ≥60 years, without pre-existing AD diagnoses, and pursued medical services in the United States from October 2015 to September 2016. Cohorts 1 (N = 46,218) and 2 (N = 32,923) had HIV. Cohort 1 had prescription claims for at least one NRTI within the exposure period; Cohort 2 did not. Cohort 3 (N = 150,819) had medical claims for the common cold without evidence of HIV or antiretroviral therapy.

We identified a statistically significant positive association between NRTI exposure and decreased risk for sporadic AD in patients with HIV and ≥60 years of age. Age-adjusted and sex-adjusted hazard ratio (HR) showed a significantly decreased risk for AD in Cohort 1 compared with Cohorts 2 (HR 0.88) and 3 (HR 0.84). Post-marketing surveillance of NRTIs has shown acceptable safety data sufficient to allow NRTIs to be prescribed, as a class, continuously since 1987, and tens of thousands of patients ≥60 years of age are currently taking these medications, providing support that these agents will be well tolerated in aged patients. The data presented here support controlled clinical trials using NRTIs on patients with mild cognitive impairment (MCI), pre-symptomatic familial AD, Down syndrome, and sporadic AD, along with asymptomatic APOE4 carriers.

Researchers here report on the importance of molecular chaperones, and cyclophilin A in particular, to the function of hematopoietic stem cells. These cells generate red blood cells and immune cells, and thus age-related changes in hematopoietic function have important consequences for health. The immune system runs awry with age, and altered hematopoiesis is one of the contributing factors. If, as researchers here suggest, upregulation of cyclophilin A can improve hematopoietic stem cell function, then using this as a basis for therapy may produce health benefits in older individuals.

Hematopoietic stem cells (HSCs) are remarkably long-lived. HSCs typically remain dormant within the bone marrow, yet they possess the ability to activate and replenish blood cells continuously, maintaining a relatively youthful profile throughout the life of an organism. A driving force of cellular aging is the accumulation of proteins that have reached the end of their useful life. With age, proteins tend to misfold, aggregate, and accumulate inside the cell, which leads to toxic stress that can disrupt cell function. Cells that frequently engage in cell division, like progenitor cells, can dispose of protein aggregates through dilution. On the other hand, long-lived HSCs, which do not divide often, face the problem of the accumulation of misfolded proteins and subsequent toxic stress. Nevertheless, HSCs remain impervious to aging. How do they do it?

Previous studies have shown that mammalian cells express hundreds of molecular chaperones, proteins that preserve or change the three-dimensional conformation of existing proteins. Cyclophilins, one of the most abundant chaperones, have been implicated in the aging process. However, how they affect cellular proteins has not previously been studied. Working with mice, the researchers first characterized the protein content of HSCs and discovered that cyclophilin A is a prevalent chaperone. Further experiments showed that the expression of cyclophilin A was significantly decreased in aged HSCs, and genetically eliminating cyclophilin A accelerated natural aging in the stem cell compartment. In contrast, reintroducing cyclophilin A into aged HSCs enhanced their function. Together, these findings support cyclophilin A as a key factor in the longevity of HSCs.

Link: https://blogs.bcm.edu/2024/04/30/from-the-labs-uncovering-the-secret-of-long-lived-stem-cells/

Researchers here report on their efforts to interfere in a mechanism causing loss of the myelin that sheathes nerves. The driving goal is to produce a therapy for the severe demyelinating disease of multiple sclerosis rather than to reverse the lesser degree of myelin loss that occurs for everyone in later life. The animal evidence suggests that it may also prove to be useful in the general population of older individuals, however, which is promising. Loss of myelin is thought to contribute to some fraction of age-related loss of cognitive function, and so reversing that loss is an important goal.

Oligodendrocytes (OLs) are responsible for producing myelin sheaths that wrap around cable-like parts of nerve cells called axons, much like the plastic insulation around a wire. When the protective myelin gets damaged, be it by disease or the wear and tear of age, nerve signaling gets disrupted. Depending on where the damaged nerves lead, the disruptions can affect movement, vision, thinking and so on.

Analysis of stored autopsy tissues revealed that OLs within multiple sclerosis (MS) lesions lacked an activating histone mark called H3K27ac, while expressing high levels of two other repressive histone marks H3K27me3 and H3K9me3 associated with silencing gene activity. The research team scoured a library of hundreds of small molecules known to target enzymes that could modify gene expression and influence the silenced OLs. The team determined that the compound ESI1 (epigenetic-silencing-inhibitor-1) was nearly five times more powerful than any other compounds they considered.

The compound tripled the levels of the desired H3K27ac histone mark in OLs while sharply reducing levels of the two repressive histone marks. In both aging mice and mice mimicking MS, the ESI1 treatment prompted myelin sheath production and improved lost neurological function. Testing included tracking gene activation, measuring the microscopic new myelin sheaths surrounding axons, and observing that treated mice were quicker at navigating a water maze.

Link: https://www.eurekalert.org/news-releases/1043326

One of the important points made by advocates for the treatment of aging is that one cannot distinguish between aging and age-related disease. They are one and the same. There is no magical state of "healthy aging" in which one doesn't suffer eventual disease. A decline of function in aging that does not rise to the level required to call it a disease is the subclinical stage of that disease; all the same damage has taken place under the hood, just less of it. Conversely, an age-related disease is just another facet of aging, a collection of damage and consequences of damage that becomes sizable enough to reach the definition of disease. Whether or not any specific age-related dysfunction is called a disease is just a matter of whether the degree of dysfunction is on one side or another of an arbitrary line drawn in the sand.

The authors of today's open access paper take this point and then build on it to suggest that the most robust age-slowing approaches demonstrated in animal models should be tested more rigorously in patients with common, hard-to-treat conditions such as Alzheimer's disease. The approaches with the best data include calorie restriction and all of the calorie restriction mimetic interventions that seek to replicate some part of the sweeping cellular reaction to a reduced intake of calories. Interestingly, this hasn't been well tested in Alzheimer's patients. Perhaps it should be, even given that the research community expects effects on aging to be lower in long-lived species than in short-lived species. While calorie restriction extends mouse life span by as much as 40%, it certainly doesn't do that well in humans. The actual number has yet to be established, but it would be surprising to see that the effect of long-term calorie restriction or equivalent intermittent fasting in humans is larger than a few years of additional life span.

Aging as a target for the prevention and treatment of Alzheimer's disease

Alzheimer's disease (AD), the most common etiology of dementia in older adults, is projected to double in prevalence over the next few decades. Current treatments for AD manage symptoms or slow progressive decline, but are accompanied by significant inconvenience, risk, and cost. Thus, a better understanding of the risk factors and pathophysiology of AD is needed to develop novel prevention and treatment strategies.

While a mayfly has a lifespan of one day, an elephant's lifespan may exceed 100 years. Clearly, lifespan and aging are biological traits regulated by genetics and molecular signaling pathways - that may be exploited as a therapeutic target. Aging, however, is not recognized as a disease by the U.S. Food and Drug Administration. Thus, there are no FDA-approved treatments specifically for aging. Aging, however, is the most important risk factor for multiple diseases, including dementia and AD. As molecular mechanisms regulating aging are coming to light and signaling pathways uncovered, novel therapeutic targets present an alternative approach: instead of targeting one disease at a time - leading to the inconvenience, cost, and risk of polypharmacy - targeting aging directly may prevent or slow multiple age-related diseases. Calorie restriction (CR) may be a promising preventive or therapeutic option for individuals at risk for AD or already within the AD spectrum. However, current data are limited and human studies are scarce. Additional preclinical and human studies are now warranted to discover the pathways regulated by CR and to identify pharmacophores that mimic the beneficial effects of CR.

Hypotheses linking CR and weight loss to alterations in biomarkers of aging and AD may suggest novel treatment targets and strategies-and not just for AD. Newly discovered therapies may be safe and effective for prevention and/or as an adjunct to FDA-approved treatments for individuals in the AD spectrum. Prevention and treatment strategies targeting aging may be safer and more effective than the currently available treatments targeting more downstream pathways. While several studies are in progress (listed above), more are needed. In the meantime, AD trials should consider including biomarkers of aging and aging studies should include AD biomarkers.

Microglia are innate immune cells resident in the brain, analogous to macrophages elsewhere in the body, but with the addition of a portfolio of duties relating to the maintenance of neural function. With age ever more microglia become overly inflammatory, contributing to disruptive, unresolved inflammatory signaling, and abandoning their tissue maintenance tasks. This is thought to be an important contribution to neurodegenerative conditions and loss of cognitive function more generally. Researchers here report that the adoption of an inflammatory state is a progressive dysfunction for individual microglia, not just a matter of how many microglia have switched over to undertake inflammatory behavior.

Numerous studies have indicated that aged microglia are inflamed, have reduced phagocytic capacity, and have decreased motility. Microglia exhibit several hallmarks of aging that potentially contribute to their age-related dysfunction, such as shortened telomeres, altered intercellular communication, molecular alterations, and a loss of proteostasis. Furthermore, many recent studies have started to reveal the molecular changes that define microglial aging. Single cell RNA-Seq (scRNA-Seq) analyses indicate that microglia isolated from the entire brain lose homeostasis and activate inflammatory transcriptional profiles with age. Data rich studies have also revealed partial overlaps between aging microglia and those from disease models, including Alzheimer's disease.

Studies using aged plasma administration and heterochronic blood exchange demonstrate that microglia aging is in part driven by the aged systemic environment. However, the genesis of age-related dystrophic microglial phenotypes has not been extensively investigated. So, we set out to characterize the progression of age-related hippocampal microglial dysfunction, aiming to uncover intermediate states that could be intrinsic to the aging process. To do so, we undertook complementary cellular and molecular analyses of microglia across the adult lifespan and in heterochronic parabiosis - an experimental model of aging in which the circulatory systems of young adult and aged animals are joined.

In this study, we report that microglia in the adult mouse hippocampus, a brain region responsible for learning and memory and susceptible to age-related cognitive decline, advance through intermediate states that drive inflammatory activation during aging. We utilize scRNA-Seq across the adult lifespan to identify intermediate transcriptional states of microglial aging that emerge following exposure to an aged systemic environment. Functionally, we tested the role of these intermediate states using in vitro microglia approaches and an in vivo temporally controlled adult microglia-specific Tgfb1 conditional genetic knockout mouse model to demonstrate that intermediates represent checkpoints in the progression of microglia from homeostasis to inflammatory activation, with functional implications for hippocampal-dependent cognitive decline.

Link: https://doi.org/10.1101/2024.04.09.588665

As an atherosclerotic plaque grows into a hotspot of inflammation and cell dysfunction in a blood vessel wall, it starts to draw in the nearby vascular smooth muscle cells that wrap the outside of the vessel. As researchers here note, these smooth muscle cells are altered by the plaque environment in ways that are analogous to the behavior of cancerous cells. They change, multiply, and accelerate the growth of a fatty plaque that will eventually rupture to cause a stroke or heart attack by blocking a downstream blood vessel.

Atherosclerosis is the major cause of heart attacks and stroke around the world and occurs when fat deposits build up inside the arteries. Atherosclerosis can be reduced with a healthy diet or drugs called statins that slow or reverse the buildup of deposits. Previous studies had found that smooth muscle cells metamorphose into different types of cells inside these atherosclerotic plaques and multiply to make up most cells within the plaques. Yet until now, few studies had examined the cancer-like properties of the cells and if these changes contributed to atherosclerosis. To learn more, researchers closely tracked the development of transformed smooth muscle cells in mice with atherosclerosis and sampled plaques of people with atherosclerosis. They found striking parallels between changes in the smooth muscle cells and tumor cells, including hyperproliferation, resistance to cell death, and invasiveness.

DNA damage, another hallmark of cancer, accumulated in the mouse and human smooth muscle cells and appears to accelerate atherosclerosis, the researchers found. The researchers could further accelerate atherosclerosis in mice by introducing a genetic mutation that increased DNA damage within the smooth muscle cells. Vascular tissue from healthy mice and people had no signs of smooth muscle cells with the DNA damage found in atherosclerotic plaques. "The cells stay inside existing plaques, which makes us think that they behave mostly like benign tumor cells, but more work needs to be done in humans and animal models to address this hypothesis." If atherosclerosis is driven by cancer-like cells, anticancer therapies may be a potential new way to treat or prevent the disease.

Link: https://www.eurekalert.org/news-releases/1043152

Chronic, unresolved inflammation is a feature of aging. When the immune system is constantly active in this way, the consequent altered cell behavior throughout the body becomes disruptive to tissue and organ function, harmful to the individual. Chronic inflammation accelerates the onset and progression of all of the common fatal age-related conditions. This unwanted inflammatory signaling arises from many different roots, including the growing presence of senescent cells, but also the interaction of innate immune sensors with other forms of age-related dysfunction. For example, damage-associated molecular patterns such as mislocalized fragments of mitochondrial DNA leaking from dysfunctional mitochondria into the cell cytosol can trigger cGAS/STING signaling. This mechanism evolved to detect the presence of bacterial DNA, and unfortunately runs awry with age.

The challenge inherent in dampening age-related chronic inflammation is that, so far, it appears to use exactly the same pathways that are involved in the normal, necessary, short-term inflammatory response to injury, pathogens, potentially cancerous cells, and so forth. All of the approaches developed to date to suppress the overactivity of an immune system also suppress necessary functions, and that produces unpleasant long-term consequences. This is well established via the use of immunosuppressant drugs in patients with autoimmune disease. There was some hope that targeting aspects of cGAS/STING function would prove to be a better option, but as researchers note in today's open access paper, an operating cGAS/STING pathway appears to be necessary for long-term health.

STING promotes homeostatic maintenance of tissues and confers longevity with aging

Local immune processes within aging tissues are a significant driver of aging associated dysfunction, but tissue-autonomous pathways and cell types that modulate these responses remain poorly characterized. The cytosolic DNA sensing pathway, acting through cyclic GMP-AMP synthase (cGAS) and Stimulator of Interferon Genes (STING), is broadly expressed in tissues, and is poised to regulate local type I interferon (IFN-I)-dependent and independent inflammatory processes within tissues. Recent studies suggest that the cGAS/STING pathway may drive pathology in various in vitro and in vivo models of accelerated aging.

To date, however, the role of the cGAS/STING pathway in physiological aging processes, in the absence of genetic drivers, has remained unexplored. This remains a relevant gap, as STING is ubiquitously expressed, implicated in multitudinous disorders, and loss of function polymorphisms of STING are highly prevalent in the human population (an incidence of more than 50%). Here we reveal that, during physiological aging, STING-deficiency leads to a significant shortening of murine lifespan, increased pro-inflammatory serum cytokines and tissue infiltrates, as well as salient changes in histological composition and organization.

We note that aging hearts, livers, and kidneys express distinct subsets of inflammatory, interferon-stimulated gene (ISG), and senescence genes, collectively comprising an immune fingerprint for each tissue. These distinctive patterns are largely imprinted by tissue-specific stromal and myeloid cells. Using cellular interaction network analyses, immunofluorescence, and histopathology data, we show that these immune fingerprints shape the tissue architecture and the landscape of cell-cell interactions in aging tissues. These age-associated immune fingerprints are grossly dysregulated with STING-deficiency, with key genes that define aging STING-sufficient tissues greatly diminished in the absence of STING. This altered homeostasis in aging STING-deficient tissues is associated with a cross-tissue loss of homeostatic tissue-resident macrophage (TRM) populations in these tissues. Ex vivo analyses reveal that basal STING- signaling limits the susceptibility of TRMs to death-inducing stimuli and determines their in situ localization in tissue niches, thereby promoting tissue homeostasis.

Collectively, these data upend the paradigm that cGAS/STING signaling is primarily pathological in aging and instead indicate that basal STING signaling sustains tissue function and supports organismal longevity. Critically, our study urges caution in the indiscriminate targeting of these pathways, which may result in unpredictable and pathological consequences for health during aging.

Dasatinib and quercetin used in combination clears a fraction of lingering senescent cells in aging mice, producing a sizable degree of rejuvenation, and reversal of aspects of many different age-related conditions. In humans, clinical trials are underway at a sedate pace. Dasatinib is a chemotherapeutic small molecule, while quercetin is a plant extract flavonol. Here, researchers discuss their search for plant extract alternatives that mimic the effects of dasatinib, in the hopes of producing a less regulated alternative to the use of a small molecule drug, thereby lowering the barrier to entry somewhat. Size of effect is important, however, and it is yet to be demonstrated that any of their proposed alternatives can replicate the degree to which dasatinib impacts senescent cells.

The major risk factor for chronic disease is chronological age, and age-related chronic diseases account for the majority of deaths worldwide. Targeting senescent cells that accumulate in disease-related tissues presents a strategy to reduce disease burden and to increase healthspan. The senolytic combination of the tyrosine-kinase inhibitor dasatinib and the flavonol quercetin is frequently used in clinical trials aiming to eliminate senescent cells.

Here, our goal was to computationally identify natural senotherapeutic repurposing candidates that may substitute dasatinib based on their similarity in gene expression effects. The natural senolytic piperlongumine (a compound found in long pepper), and the natural senomorphics parthenolide, phloretin, and curcumin (found in various edible plants) were identified as potential substitutes of dasatinib. The gene expression changes underlying the repositioning highlight apoptosis-related genes and pathways. The four compounds, and in particular the top-runner piperlongumine, may be combined with quercetin to obtain natural formulas emulating the dasatinib + quercetin formula.

Link: https://doi.org/10.1038/s41598-024-55870-4

Researchers have found evidence of cellular senescence in neurons in the aging brain. How do neurons become senescent, given that they are post-mitotic, non-dividing cells? Cellular senescence is state primarily associated with excessive cell division, in which a cell reaches the Hayflick limit, though cells can become senescent in response to damage or toxicity. Here, researchers provide evidence to show that in the aging brain, and particularly in the context of neurodegenerative conditions, ever more neurons re-enter the cell cycle, which inevitably leads to senescence. This is an interesting line of research, adding another argument for the use of senolytic drugs to treat neurodegenerative conditions.

Increasing evidence indicates that terminally differentiated neurons in the brain may recommit to a cell cycle-like process during neuronal aging and under disease conditions. Because of the rare existence and random localization of these cells in the brain, their molecular profiles and disease-specific heterogeneities remain unclear. Through a bioinformatics approach that allows integrated analyses of multiple single-nucleus transcriptome datasets from human brain samples, these rare cell populations were identified and selected for further characterization.

Our analyses indicated that these cell cycle-related events occur predominantly in excitatory neurons and that cellular senescence is likely their immediate terminal fate. Quantitatively, the number of cell cycle re-engaging and senescent neurons decreased during the normal brain aging process, but in the context of late-onset Alzheimer's disease (AD), these cells accumulate instead. Transcriptomic profiling of these cells suggested that disease-specific differences were predominantly tied to the early stage of the senescence process, revealing that these cells presented more proinflammatory, metabolically deregulated, and pathology-associated signatures in disease-affected brains. Similarly, these general features of cell cycle re-engaging neurons were also observed in a subpopulation of dopaminergic neurons identified in the Parkinson's disease (PD)-Lewy body dementia (LBD) model.

An extended analysis conducted in a mouse model of brain aging further validated the ability of this bioinformatics approach to determine the robust relationship between the cell cycle and senescence processes in neurons in this cross-species setting.

Link: https://doi.org/10.1371/journal.pbio.3002559

Transdifferentiation is the use of various techniques to convert a somatic cell of one type directly into a somatic cell of another type. This is an alternative to first using Yamanaka factors to dedifferentiate somatic cells into induced pluripotent stem cells, then guiding differentiation into the desired final somatic cell type. For both differentiation from pluripotency to somatic cell and transdifferentiation between somatic cells, a suitable recipe of factors and altered gene expression must be discovered for any given destination. A few of these protocols are now well known, but the vast majority have yet to be robustly established, or even attempted at all.

In today's open access paper, researchers refer to transdifferentiation as direct reprogramming, not to be confused with the various forms of reprogramming via Yamanaka factors, either to produce induced pluripotent stem cells, or to restore youthful epigenetic patterns via what is known as partial reprogramming or epigenetic reprogramming. Transdifferentiation offers the potential to treat aspects of aging and age-related disease that involve the loss of small, specific cell populations, such as dopaminergenic neurons or sensory hair cells. These critical populations are surrounded by other, more numerous, less critical cells, which might be targets for transdifferentiation given a sufficiently selective therapy. Proof of concept in these and a few other cases has been achieved in animal studies, and it remains to be seen as to how rapidly this can advance to the clinic.

Next-generation direct reprogramming

While the concept that mature cell states are stable holds the key for homeostasis of an organism, the long-held believe was that this state cannot ever be reversed. This fallacy has gradually broken down. Now, the Yamanaka factors are now widely used not only for reprogramming but also for partial reprogramming that leads to rejuvenation of tissues. Yet another kind of reprogramming was emerging from the basic science field, now dubbed direct reprogramming, or transdifferentiation (we use the terms interchangeably from here on). During transdifferentiation a differentiated cell changes its fate to another, more desired differentiated cell type, without entering a pluripotent stage. The first identified transcription factor capable of directly reprogramming fibroblasts to skeletal muscles was MyoD. Many other lineage-specific transcription factors capable of transdifferentiating a target cell have since been identified.

Whether induced or endogenous process, in general, pioneer factors (PF) act as the first responders in direct reprogramming by binding and opening closed chromatin. It is not clear if each transdifferentiation lineage is regulated by a specific pioneer factor, or if a universal PF for transdifferentiation (capable of initiating multitude of direct lineage reversions) is still to be identified. Transdifferentiation studies have unveiled the opportunities and offer applications in regenerative therapies, such as cell replacement therapy or immunotherapy. The key question, and the topic of this review is to identify new, feasible methods to induce specific, high efficiency and targeted transdifferentiation.

These next-generation transdifferentiation approaches will come with better efficiency and plausibly with potential to treat diseases like Alzheimer's disease, muscle injury, diabetes, or myocardial infarction, resulting in elimination of the unsurmountable treatment issues at the moment (for example, finding a right donor or graft rejections). These novel approaches will enhance the efficacy and safety of direct reprogramming, allowing the ultimate decoding of the process towards plausibly resulting in 21st century personalized regenerative medicine.

Both cancer and aging impair the activity of T cells of the adaptive immune system, forcing these cells into exhaustion and senescence. The state of exhaustion is incompletely understood, but appears as an issue in immunotherapies making use of engineered T cells, as well as in the natural population of the aged body. Since researchers are already altering the T cells used in cancer therapies, why not alter them further to make them more able to resist the effects of aging cancer on T cell populations in the body? This is an interesting and plausible goal, but one that requires a greater understanding of T cell exhaustion than presently exists.

Cellular immunotherapy is revolutionizing oncology by harnessing T cells' unique ability to specifically target and potentially cure metastatic cancer, a feat not achievable with traditional treatments. Living T cells have proven they can eradicate even the most stubborn metastatic cells. However, challenges persist, as these therapies sometimes fail when T cells do not endure, often succumbing to exhaustion or senescence. This issue is being addressed by researchers who are exploring methods to enhance T cell resilience and functionality.

Evolution has shaped T cells to occasionally dampen their function in chronic viral infections to prevent autoimmunity and mitigate potential harm from an overly aggressive immune response. For example, the immune system's complete elimination of a hepatitis virus could cause significant liver damage. Chronic activation can also drive T cells toward senescence and exhaustion, weakening the immune response to cancer. To address these challenges, researchers have developed checkpoint inhibitors and engineered T cells to create synthetic T cells that can reverse or bypass these evolutionary constraints with great success in some indications.

Researchers have developed a synthetic T cell state they call TIF (T cells with an immortal-like and functional state). TIF cells are the product of disrupting the BCOR and ZC3H12A genes, a result that is surprising because these genes are typically expressed at low levels in T cells and lack dynamic regulation. This approach is aimed at addressing the traditional trade-off in T cell therapies between longevity and potency, offering cells that not only persist longer but also retain robust anti-tumor capabilities. TIF cells demonstrate enhanced survival and can enter a reversible dormant state, like memory cells, providing long-term immunity. Without BCOR, and in combination with ZC3H12A deficiency, genes that are usually repressed might become active, enhancing both stemness- and cytotoxicity-associated genes. This could potentially remove brakes on the T cell stemness and cytotoxic programs, enhancing therapeutic efficacy.

Link: https://doi.org/10.1084/jem.20240258

Here find an open access review of the present landscape of biomarkers of aging, both single measures and composite measures of various sorts, such as the aging clocks developed over the past fifteen years. The development of a good, consensus measure of biological age would accelerate efforts to treat aging as a medical condition, as assessing the ability of various classes of treatment to slow or reverse aging is at present a slow and expensive process - the only proven approach is a life span study. Unfortunately, all present approaches to the assessment of biological age have their challenges. The accumulation of large amounts of data for analysis proceeds in parallel with the development of better aging clocks that seek to address the known issues.

One major barrier to longevity research is evaluating the impact of interventions that improve human health and longevity because they are complex processes that occur over long time scales. Instead, measurable phenotypic traits or proxies of longevity, termed longevity biomarkers, may be used to assess the effectiveness of longevity interventions, or prognosticate clinical outcomes. Longevity biomarkers are critical tools for predicting lifespan and susceptibility to age-related diseases, but there exist a dizzying array of options, with at times contradictory readouts, and other key weaknesses.

Strengths of longevity biomarkers include providing insight into an individual's biological age, as opposed to chronological age, which is pivotal in evaluating targeted interventions that address aging and age-related conditions. However, most longevity biomarkers also exhibit notable weaknesses, such as a lack of specificity and lack of standardization across different studies and applications. These weaknesses underscore the need for more research to enhance their accuracy and reliability in long-term longitudinal studies.

In the present review, we discuss key strengths and weaknesses of popular clinical biomarkers used to predict morbidity and mortality associated with advanced age, identify existing bottlenecks, and integrate the field consensus on further directions for robust lifespan and healthspan estimation.

Link: https://doi.org/10.55277/ResearchHub.dxewpyv0

There are many different ways to conceptualize programs of research and development aimed at the treatment of aging. The Strategies for Engineered Negligible Senescence (SENS) is focused on aging as damage accumulation, and treatment is thus damage repair: remove senescent cells, restore mitochondrial function, clear out harmful protein aggregates, and so forth. Programmed aging viewpoints instead focus on ways to alter what are suspected to be evolved programs that drive aging, with this line of thought most often centered around the reversal of epigenetic changes that are observed to occur with age.

In today's open access paper, the authors propose a viewpoint that they call juventology, the study of youth, in analogy to gerontology, the study of aging. Clearly calorie restriction and related interventions adjust the operation of metabolism to slow aging and prolong the period of youthful life in many species. This might be taken as the existence of youth-maintaining programs, a delay of aging programs, or a slowing of damage accumulation. People tend to see their own view of aging reflected in the data for calorie restriction. It causes such a broad set of changes in cellular biochemistry, where that biochemistry is itself not fully mapped, that it is hard to mount arguments in support of one theory of aging versus another.

Is this really a good choice of strategy, however? Do we believe that calorie restriction is a starting point for a field that will in time engineer some form of altered metabolism that is far more effective when it comes to prolonging youthful life? In principle this has to be the case, as similar species with radically different life spans exist in the wild. Compare mice with naked mole-rats, for example, a nine-fold difference in life expectancy. In practice, I suspect that engineering human cellular metabolism to this degree is a far future prospect, however. The advantage of the damage repair approach is that it does seem to offer goals that can be achieved in the near future, without a full understanding of cellular biochemistry, and which will achieve meaningful gains in life span and reduction in the burden of age-related disease.

Exploring juventology: unlocking the secrets of youthspan and longevity programs

The paradigm of longevity programs opens up new vistas for understanding interventions that extend lifespan without instigating adverse effects. While traditional aging research has often fixated on combating free radicals and oxidative stress, juventology suggests that the most effective pro-longevity interventions induce alternate survival phases. The exploration of longevity programs in model organisms reveals a complex network of cellular responses and adaptive strategies that challenge the somewhat conventional theories of aging. Especially, the interplay between nutrient availability and the activation of specific longevity programs is not just a passive response but instead highlights a sophisticated network of cellular events that over the course of the lifespan can result in a healthier aging phenotype and increased longevity. In E. coli, Saccharomyces cerevisiae, and C. elegans, starvation, the most severe form of dietary restriction, causes a major lifespan extension.

Juventology is fundamentally different from "aging-centered" theories of aging for two reasons: (1) alternative lifespan programs, such as those entered in response to starvation, can be independent (or are at least partially independent) of aging itself. As an example, one could visualize the use of target-specific pharmaceuticals or systemically broader acting periodic fasting intervals modulate the mTor-S6K and PKA pathways, which in turn can promote regeneration and rejuvenation. Notably, this can be achieved even in an organism with a high rate of aging. Thus, even in an accelerated aging phenotype, a longer healthspan and lifespan may be accomplished by periodically activating regenerative and rejuvenating processes. (2) Juventology shifts the focus from an "old or older age" paradigm characterized by high degrees of dysfunction and subsequent high morbidity and mortality, instead to the period in life during which both morbidity and mortality are very low and only difficult to detect.

Diseases in humans are generally rare before the (biological) age 40, but comorbidities are common after age 65, yet no specific field of science is focusing on how evolution resulted in a program that is extremely efficient in preventing disease for the first 40 years of life and how that program may be modulated and extended by dietary, pharmacological, or other interventions. On the one hand, developmental biology focuses on the biological process from embryo to (young) adult stage and generally does not include this important field. On the other hand, biogerontology the biological basis of aging and age-related diseases. Thus, juventology presents a complementary field to both gerontology and developmental biology that focuses on the period of organismal life when the force of natural selection is high and body functions remain maximized.

Periodic fasting and calorie restriction promote cells to enter into a stress resistance state which is characterized by the activation of cell protection, regeneration, and rejuvenation processes. Across multiple species, these protective and regenerative mechanisms are activated in part by the down-regulation of growth hormone, IGF-1, mTor-S6K, and PKA signaling cascades, which in turn induces the extension of healthspan. Because these states have evolved to withstand periods of extreme nutrient starvation, they can be viewed as alternative longevity programs activated to maintain cellular "youthspan" until resources that promote proliferative processes become available again. Here, we propose that these juventology-based approaches provide complementary strategies to the classic biogerontology approaches to focus on the earlier (i.e., biologically younger) functional period while also studying the later progressively dysfunctional processes that affect health and longevity.

Researchers here demonstrate an approach to cell therapy for an injured heart that produces lesser degrees of abnormal function than prior efforts. There has been some concern that delivering new cells to the heart to spur greater regeneration will disrupt the electrical regulation of heartbeats, as animal studies suggested an unacceptable risk of arrhythmia following treatment. This work still makes use of cardiomyocytes generated from induced pluripotent stem cells, already accomplished by a number of other groups, but differences in the details of the approach appear to make a positive change in the outcome.

In a recent study, a research team tested a new strategy for regenerative heart therapy that involves injecting 'cardiac spheroids' derived from human induced pluripotent stem cells (HiPSCs) into monkeys with myocardial infarction. First, the team verified the correct reprogramming of HiPSCs into cardiomyocytes. They observed, via cellular-level electrical measurements, that the cultured cells exhibited potential patterns typical of ventricular cells. The cells also responded as expected to various known drugs. Most importantly, they found that the cells abundantly expressed adhesive proteins such as connexin 43 and N-cadherin, which would promote their vascular integration into an existing heart. Afterwards, the cells were transported from the production facility. The cardiac spheroids, which were preserved at 4°C in standard containers, withstood the four-hour journey without problem. This means that no extreme cryogenic measures would be needed when transporting the cells to clinics, which would make the proposed approach less expensive and easier to adopt.

Finally, the monkeys received injections of either cardiac spheroids or a placebo directly into the damaged heart ventricle. During the observation period, the researchers noted that arrythmias were very uncommon, with only two individuals experiencing transient tachycardia (fast pulse) in the first two weeks among the treatment group. Through echocardiography and computed tomography exams, the team confirmed that the hearts of monkeys that received treatment had better left ventricular ejection after four weeks compared to the control group, indicating a superior blood pumping capability. Histological analysis ultimately revealed that the cardiac grafts were mature and properly connected to pre-existing existing tissue. "The favorable results obtained thus far are sufficient to provide a green light for our clinical trial. We are already employing the same cardiac spheroids on patients with ischemic cardiomyopathy."

Link: https://www.shinshu-u.ac.jp/english/topics/2024/04/using-stem-cell-deri.html

While researchers here focus specifically on stair climbing as a form of physical activity to compare against risk of mortality in later life, there are any number of other studies that focus on activity more generally, or on other forms of moderate to vigorous exercise. The consensus across epidemiological studies is that physical activity correlates with reduced mortality. Animal studies have been used to demonstrate that the exercise in fact causes that reduced mortality, and it is reasonable to consider that the same is true in humans.

Cardiovascular disease is largely preventable through actions like exercise. However, more than one in four adults worldwide do not meet recommended levels of physical activity. Stair climbing is a practical and easily accessible form of physical activity which is often overlooked. This study investigated whether climbing stairs, as a form of physical activity, could play a role in reducing the risks of cardiovascular disease and premature death.

The authors collected the best available evidence on the topic and conducted a meta-analysis. Studies were included regardless of the number of flights of stairs and the speed of climbing. There were nine studies with 480,479 participants in the final analysis. The study population included both healthy participants and those with a previous history of heart attack or peripheral arterial disease. Ages ranged from 35 to 84 years old and 53% of participants were women.

Compared with not climbing stairs, stair climbing was associated with a 24% reduced risk of dying from any cause and a 39% lower likelihood of dying from cardiovascular disease. Stair climbing was also linked with a reduced risk of cardiovascular disease including heart attack, heart failure, and stroke.

Link: https://www.eurekalert.org/news-releases/1042193

Atherosclerosis is the growth of fatty lesions in blood vessel walls, ultimately leading to a heart attack or stroke when an unstable lesion ruptures. Atherosclerosis is primarily a condition of macrophage dysfunction, in which these cells fail to keep up with their task of removing excess cholesterol from blood vessel walls in order to return it to to the bloodstream for transport back to the liver. The local excess of cholesterol is largely the proximate cause of this macrophage dysfunction, so as the amount of cholesterol grows, macrophages become ever less capable of dealing with it. They die, adding their mass to the lesion, while signaling for reinforcements that will suffer the same fate.

That said, this is a description of how atherosclerosis progresses once it gets started. How do the initial small excesses of cholesterol form in the first place? Most of the underlying root causes of aging are involved in the growing inability of macrophages to keep up with the task of cholesterol transport. Further, altered behavior of other cell populations with advancing age, in the liver and blood vessel walls, may be capable of disrupting cholesterol transport from the liver to the rest of the body, leading to excess deposits in blood vessels. In today's open access paper, researchers focus in on the age-related decline in mitochondrial function in the context of atherosclerosis: would improving mitochondrial function help?

Effects of mitochondrial dysfunction on cellular function: Role in atherosclerosis

Atherosclerosis is the basis of a large proportion of fatal cardiovascular events, and a significant number of cardiovascular-related deaths can be attributed to the rupture of atherosclerotic plaques. Thinning of the covered fibrous cap formed by vascular smooth muscle cells (VSMCs) results in cap rupture and erosion, which is responsible for the majority of cardiovascular-related deaths from myocardial infarction and stroke. Atherosclerosis is an age-associated disorder; however, with the development of non-invasive diagnostic methods and the accumulation of knowledge in postmortem research, asymptomatic lesions have been described in young adults, suggesting that atherosclerosis is a chronic disease that develops at a much younger age than previously thought.

Atherosclerosis is now widely accepted to begin with endothelial dysfunction and lipid deposits, which progress through macrophage infiltration. In atherosclerosis-prone areas, the chronic inflammatory response and impaired lipoprotein metabolism are among the major contributors to atherosclerotic lesion formation. The first idea linking mitochondria to atherosclerosis was reported in 1970, but it is only recently that increasing evidence has highlighted the key role of mitochondrial dysfunction in the pathogenesis of atherosclerosis. Mitochondrial dysfunction can induce high levels of oxidative stress and high rates of apoptosis, which can cause endothelial dysfunction and increase the vascular disease burden. The increase in reactive oxygen species (ROS) production in mitochondria, accumulation of mitochondrial DNA damage, and progressive respiratory chain dysfunction are all related to atherosclerosis.

Mitochondrial dysfunction is believed to result in an increase in reactive oxygen species, leading to oxidative stress, chronic inflammation, and intracellular lipid deposition, all of which can contribute to the pathogenesis of atherosclerosis. Critical cells, including endothelial cells, vascular smooth muscle cells, and macrophages, play an important role in atherosclerosis. Mitochondrial function is also involved in maintaining the normal function of these cells. To better understand the relationship between mitochondrial dysfunction and atherosclerosis, this review summarizes the findings of recent studies and discusses the role of mitochondrial dysfunction in the risk factors and critical cells of atherosclerosis.

The author of this paper is an advocate for programmed aging. This is the view that degenerative aging is actively selected by evolutionary processes, perhaps because it helps to reduce the risk of runaway population growth, or perhaps because aging species better adapt to ecological change, rather than being a side-effect of selection effects focused on early life reproductive success that tend to produce systems that accumulate damage to fail over time. In some programmed aging views, epigenetic change is close to being the root cause of aging, being the implementation of an evolutionarily selected program. It is interesting to see an outline of perceived challenges in epigenetic clock development from the programmed aging viewpoint, to contrast with the challenges seen by other researchers, which are focused on the lack of understanding of how specific epigenetic changes reflect underlying damage and dysfunction.

Late in life, the body is at war with itself. There is a program of self-destruction (phenoptosis) implemented via epigenetic and other changes. I refer to these as type (1) epigenetic changes. But the body retains a deep instinct for survival, and other epigenetic changes unfold in response to a perception of accumulated damage (type (2)).

In the past decade, epigenetic clocks have promised to accelerate the search for anti-aging interventions by permitting prompt, reliable, and convenient measurement of their effects on lifespan without having to wait for trial results on mortality and morbidity. However, extant clocks do not distinguish between type (1) and type (2). Reversing type (1) changes extends lifespan, but reversing type (2) shortens lifespan. This is why all extant epigenetic clocks may be misleading.

Separation of type (1) and type (2) epigenetic changes will lead to more reliable clock algorithms, but this cannot be done with statistics alone. New experiments are proposed. Epigenetic changes are the means by which the body implements phenoptosis, but they do not embody a clock mechanism, so they cannot be the body's primary timekeeper. The timekeeping mechanism is not yet understood, though there are hints that it may be (partially) located in the hypothalamus. For the future, we expect that the most fundamental measurement of biological age will observe this clock directly, and the most profound anti-aging interventions will manipulate it.

Link: https://doi.org/10.1134/S0006297924020135

The progressive dysfunction of sweat glands in the skin is probably not high on the list of items that people think about in the context of degenerative aging, at least not until they experience it. A reduced capacity of sweat glands leads to heat intolerance, and it is one of the contributing causes of the raised mortality rate among the elderly in heat waves. Here, researchers examine some of the biochemistry of sweat gland cells in aging mice. They focus in on a number of proteins that may turn out to be viable targets for drugs to force sweat glands in aged skin back to a more youthful degree of function. It is a long road from fundamental investigations of this sort to that outcome, however.

Evaporation of sweat on the skin surface is the major mechanism for dissipating heat in humans. The secretory capacity of sweat glands (SWGs) declines during aging, leading to heat intolerance in the elderly, but the mechanisms responsible for this decline are poorly understood. We investigated the molecular changes accompanying SWG aging in mice, where sweat tests confirmed a significant reduction of active SWGs in old mice relative to young mice.

We first identified SWG-enriched messenger RNAs (mRNAs) by comparing the skin transcriptome of Eda mutant Tabby male mice, which lack SWGs, with that of wild-type control mice by RNA-sequencing analysis. This comparison revealed 171 mRNAs enriched in SWGs, including 47 mRNAs encoding 'core secretory' proteins such as transcription factors, ion channels, ion transporters, and trans-synaptic signaling proteins. Among these, 28 SWG-enriched mRNAs showed significantly altered abundance in the aged male footpad skin, and 11 of them, including Foxa1, Best2, Chrm3, and Foxc1 mRNAs, were found in the 'core secretory' category.

Consistent with the changes in mRNA expression levels, immunohistology revealed that higher numbers of secretory cells from old SWGs express the transcription factor FOXC1, the protein product of Foxc1 mRNA. In sum, our study identified mRNAs enriched in SWGs, including those that encode core secretory proteins, and altered abundance of these mRNAs and proteins with aging in mouse SWGs.

Link: https://doi.org/10.18632/aging.205776

Robust modern forms of vaccination that were developed in the 20th century remain one of the most important forms of medical technology. Infectious diseases are not going away any time soon, and continue to cause a sizable fraction of human mortality, even though that fraction is much reduced in our era. Unfortunately, effective vaccination depends on an effective immune system, and thus vaccines tend to perform increasingly poorly with advancing age. As we age our immune system becomes ever less capable, a decline into immunosenescence caused by a range of contributing processes: involution of the thymus, where T cells of the adaptive immune system mature; a growing presence of senescent, exhausted, and malfunctioning immune cells; a shift in cell populations of the bone marrow to produce more myeloid and fewer lymphoid cells; and so forth.

As today's open access paper points out, the approach to improving vaccination in the old has long been to find ways to work around the growing incapacity of the aged immune system. Developing better adjuvants to vaccines, for example. This produces only incremental gains. The yearly toll of influenza deaths is much larger than the estimates of prevented deaths due to widespread vaccination. For the 2022-2023 season those numbers show 21,000 estimated deaths versus 3,600 estimated prevented deaths. Most of those deaths are old people, not only less able to defend against an infectious pathogen, but also less able to benefit from vaccination. Something must change! That change must be to focus on ways to repair the aged immune system, restore its function to more youthful capabilities.

There are any number of approaches presently under development that show promise. Restoration of active thymic tissue would help by providing a supply of new T cells. Use of CASIN can produce lasting improvements in hematopoietic stem cell function in the bone marrow following a single treatment. Clearance of populations of malfunctioning immune cells has been demonstrated to improve immune function in animal models. Clearance of senescent cells can reduce the burden of unresolved inflammatory signaling that puts stress on the aged immune system. There are more in various stages of development.

Insights into vaccines for elderly individuals: from the impacts of immunosenescence to delivery strategies

The global population is entering an era of aging. Older people are more susceptible to pathogens and have higher rates of morbidity and mortality. Despite the significant success of current vaccine products, many commercial vaccines fail to generate effective and long-lasting immune protection in elderly individuals. With increasing age, the reasons for the decline in vaccine potency are multifactorial. Age-related dysregulation of lymph nodes, and crucial immune cells jointly reduces the efficiency of vaccination. With the continuous emergence of new pathogens, it is urgent to create strategies to improve vaccination-mediated protection for elderly individuals.

The existing approaches are primarily aimed at optimizing the vaccine delivery system rather than inhibiting the immunosenescence of the immune microenvironment in elderly individuals. Inhibiting the immunosenescence of elderly individuals can evoke strong and long-lasting immune protection, which serves as a critical measure to improve vaccine-induced immunity. Although inhibition of immunosenescence most likely requires continuous intervention/treatment and is complicated to achieve, we believe that sustained-release vaccination/adjuvants or booster immunizations may sustainably ameliorate immunosenescence in the elderly. Once the immunosenescence of the elderly is corrected, their immune efficacy against various antigens can be improved.

An attractive research direction will be discovering immunomodulators and vaccine formulations that can inhibit immunosenescence. The selection of adjuvants can greatly impact the type and magnitude of the immune response. Considering the special immune status of elderly individuals, designing tailored vaccine adjuvants is indispensable for the development of next-generation vaccines for older individuals. A chronic inflammatory state also accompanies immunosenescence. However, the common opinion is that adjuvants promote immunity by inducing local inflammation. Therefore, more in-depth studies are needed to explain the role of inflammation in vaccine-induced immunity and tune the contradictory perspectives.

Most studies focus on one or several cell types or certain processes of the immune response. However, our immune system is a complex and coordinated comprehensive network. More new technologies and advances will help reveal the complexity underlying the human immune system. We must pay more attention to the impacts of versatile cells or multiple immune cascade processes. Future research should focus on developing scientific methods to build more convincing models of aging and study the profound mechanisms underlying age-related alterations that impact the immune responses of older people.

One the important themes of the research and development at Repair Biotechnologies is that localized excesses of cholesterol arise with age, leading to excess intracellular cholesterol, which is a pathological mechanism that disrupts cell behavior and kills cells. Getting rid of these localized excesses of cholesterol is challenging, however, unless resorting to some form of engineered protein machinery or gene therapy. Cells cannot break down cholesterol and there is no good way to bind enough of the excess cholesterol to some form of small molecule for sequestration and disposal without also targeting vital cholesterol in cell membranes and elsewhere. As this paper notes, excess cholesterol is clearly a meaningful problem in aging.

Although dysregulated cholesterol metabolism predisposes aging tissues to inflammation and a plethora of diseases, the underlying molecular mechanism remains poorly defined. Here, we show that metabolic and genotoxic stresses, convergently acting through liver X nuclear receptor, upregulate CD38 to promote lysosomal cholesterol efflux, leading to nicotinamide adenine dinucleotide (NAD+) depletion in macrophages. Cholesterol-mediated NAD+ depletion induces macrophage senescence, promoting key features of age-related macular degeneration (AMD), including subretinal lipid deposition and neurodegeneration.

NAD+ augmentation reverses cellular senescence and macrophage dysfunction, preventing the development of AMD phenotype. Genetic and pharmacological senolysis protect against the development of AMD and neurodegeneration. Subretinal administration of healthy macrophages promotes the clearance of senescent macrophages, reversing the AMD disease burden. Thus, NAD+ deficit induced by excess intracellular cholesterol is the converging mechanism of macrophage senescence and a causal process underlying age-related neurodegeneration.

Link: https://doi.org/10.1016/j.celrep.2024.114102

Improved autophagy is implicated in many of the approaches shown to slow aging in animal models. An open question is whether more targeted approaches to altering the regulation of autophagy in aged cells can improve matters to a greater degree than, for example, exercise or the practice of calorie restriction, both of which are known to produce general improvements in autophagy. Researchers here show that improvement of autophagy via increased expression of TRP53INP2 in old mice can reduce the age-related loss muscle mass and function that leads to sarcopenia. It seems an interesting target for further development of therapies.

Sarcopenia is a major contributor to disability in older adults, and thus, it is key to elucidate the mechanisms underlying its development. Increasing evidence suggests that impaired macroautophagy/autophagy contributes to the development of sarcopenia. However, the mechanisms leading to reduced autophagy during aging remain largely unexplored, and whether autophagy activation protects from sarcopenia has not been fully addressed.

Here we show that the autophagy regulator TP53INP2/TRP53INP2 is decreased during aging in mouse and human skeletal muscle. Importantly, chronic activation of autophagy by muscle-specific overexpression of TRP53INP2 prevents sarcopenia and the decline of muscle function in mice. Acute re-expression of TRP53INP2 in aged mice also improves muscle atrophy, enhances mitophagy, and reduces reactive oxygen species (ROS) production. In humans, high levels of TP53INP2 in muscle are associated with increased muscle strength and healthy aging. Our findings highlight the relevance of an active muscle autophagy in the maintenance of muscle mass and prevention of sarcopenia.

Link: https://doi.org/10.1080/15548627.2024.2333717