The study was co-led by Dr Maria Carolina Florian, a researcher in the Regenerative Medicine program at IDIBELL and ICREA Research Professor, and Dr Paula Petrone, a researcher at BSC-CNS and ISGlobal, a centre supported by the la Caixa Foundation. The work formed a central part of the doctoral thesis of Pablo Iañez, a researcher at ISGlobal, and combined expertise in stem cell biology, aging, image analysis and machine learning. Their starting point was a well-known clinical and biological problem: as the body ages, the hematopoietic system, the network of organs and tissues responsible for producing blood cells, progressively loses its capacity to maintain adequate blood cell production. Measuring this decline at the level of individual stem cells is essential for understanding hematopoietic aging and for testing strategies designed to slow or reverse it.

Chromatin is the material that makes this measurement possible. It consists mainly of DNA wrapped around proteins, and its spatial organization within the nucleus regulates gene activity, ultimately determining cell identity and function. As stem cells age, this organization changes, but the changes are subtle, heterogeneous and often invisible to a trained observer looking through a microscope. That is precisely where the new model excels. ChromAgeNet is a convolutional neural network, a class of artificial intelligence model designed to analyze images, and it was trained to distinguish young from aged hematopoietic stem cells based solely on the appearance of the nucleus.

To build and train the model, the researchers used three-dimensional microscopy images of mouse hematopoietic stem cell nuclei stained with DAPI, a simple, inexpensive and widely used fluorescent dye that binds to DNA and reveals the distribution of chromatin density inside the nucleus. The choice of DAPI is significant for practical reasons. Because it is a low-cost stain that can be incorporated easily into existing microscopy protocols, the approach does not require exotic reagents or specialized sample preparation, which makes it realistic to deploy in high-throughput microscopy workflows where thousands or millions of samples must be processed automatically.

The performance results are striking. Based on the appearance of the nucleus alone, ChromAgeNet demonstrated a 77 percent probability of correctly sorting cells into two groups, young versus aged. Remarkably, this exceeded the performance of a machine learning model built on chromatin features that the researchers themselves had previously defined by hand. In other words, the deep learning system extracted predictive information from the images that went beyond the features human experts had considered informative. This is a recurring theme in modern image-based biology: neural networks can detect combinations of visual cues that no single engineered feature captures, and here those cues turned out to encode biological age.

One of the most important aspects of the work is that the aging-associated differences are not necessarily visible to the naked eye in the microscopic images. Stem cell aging is a heterogeneous process, meaning that different cells age in different ways and to different degrees, and changes in nuclear architecture can be extremely subtle. ChromAgeNet nevertheless manages to identify combinations of spatial chromatin features that carry information about the aging state of individual cells. This transforms a subjective, qualitative impression of an aged nucleus into a quantitative, scalable measurement that can be applied consistently across large cell populations.

Crucially, the team did not stop at classification. They analyzed the model’s behaviour to determine which specific features of the images were most helpful in distinguishing young cells from aged cells. This interpretability analysis identified several predictive features of the age-associated state, including chromatin entropy, a measure of the disorder or variability in chromatin organization; heterochromatin, the densely packed and generally gene-poor form of chromatin, located at the periphery of the nucleus; and certain chromatin condensates, compact clusters of the DNA-protein complex. Knowing which elements of DNA organization the model relies on allows researchers to go beyond a simple young-versus-old label and gain mechanistic insight into the nuclear architecture of aging.

This mechanistic dimension positions ChromAgeNet as a complement to existing biological age biomarkers rather than a replacement for them. The best known of these are the so-called epigenetic clocks, which estimate biological age from chemical modifications to DNA, particularly methylation patterns. Epigenetic clocks require sequencing-based measurements, whereas ChromAgeNet requires only a stained image, so the two approaches interrogate different layers of the aging process. Combining image-derived chromatin architecture with molecular biomarkers could yield a richer, multi-dimensional picture of how a given stem cell is aging and how it responds to experimental interventions.

The most forward-looking application explored in the study is screening for rejuvenation strategies. As a proof of concept, the researchers applied ChromAgeNet to aged hematopoietic stem cells that had been treated with different epigenetic drugs, asking whether the treatments produced changes in chromatin organization compatible with a younger nuclear state. The authors are careful about what this does and does not show. The results do not demonstrate that the treatments functionally rejuvenated the cells, but they do establish the potential of ChromAgeNet as a tool to detect age-associated chromatin changes in response to interventions. That distinction matters: a model that can flag candidate compounds for closer functional testing accelerates discovery without overclaiming therapeutic effect.

The combination of cheap staining, a small number of model parameters and compatibility with high-throughput microscopy makes the platform unusually scalable. In principle, the same pipeline could be used to study large libraries of compounds, rapidly identifying those that shift the nuclear architecture of aged stem cells toward a younger configuration, which would then be prioritized for deeper functional assays. To support exactly this kind of community-driven development, the researchers have released a dataset of three-dimensional images of hematopoietic stem cells together with ChromAgeNet itself. This is a meaningful contribution in its own right, because publicly available imaging datasets for hematopoietic stem cell aging are currently scarce, and shared benchmarks are what allow computational tools to be validated and improved across laboratories.

Taken together, the study demonstrates that the three-dimensional organization of DNA contains quantifiable information about the aging of blood stem cells, and that artificial intelligence can extract that information from routine microscopic images. ChromAgeNet provides a new, faster and more scalable way to study cellular aging and to explore strategies for preserving or recovering hematopoietic stem cell function. If the approach generalizes beyond mouse cells and finds adoption in screening pipelines, the humble DAPI-stained nucleus, an image type generated in cytometry and microscopy labs every day, may become one of the most informative and inexpensive windows into the biological age of the cells that keep our blood, and ultimately our bodies, running.

Subject of Research: Deep learning detection of hematopoietic stem cell aging from 3D chromatin architecture in nuclear images

Article Title: AI detects signs of aging in blood stem cells from nuclear images

Article References: AI detects signs of aging in blood stem cells from nuclear images. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: artificial intelligence, chromatin, hematopoietic stem cells, aging, DAPI staining, convolutional neural network, nuclear architecture, epigenetic drugs, rejuvenation, Aging Cell, biomarkers, high-throughput microscopy

The research team, co-led by Francesca Duncan, associate professor of reproductive science in medicine at Northwestern University Feinberg School of Medicine, and Birgit Schilling, professor and director of the Mass Spectrometry Center at the Buck Institute, set out to do something deceptively simple: look closely at what postmenopausal ovarian tissue is actually doing at the molecular level. Duncan herself admits she expected to find very little. “In the ovary, we reach a point of no return with respect to fertility in which it’s no longer producing eggs, and I would venture to say most people assume those ovaries are just sitting there doing nothing, similar to the appendix,” she said. “But that’s what makes this study very different.” Her initial prediction was that ovaries taken from 50-, 60-, 70- and 80-year-old women would all look essentially identical — egg-free and functionally dormant.

That prediction turned out to be wrong. To interrogate the tissue, the scientists moved beyond the hormones that have traditionally dominated ovarian research and instead analyzed the organ’s full protein composition at high resolution. Using advanced proteomic technologies paired with mass spectrometry — approaches capable of identifying and quantifying thousands of proteins simultaneously — Schilling’s team, spearheaded by staff scientist Mark Watson, profiled 5,812 protein groups in normal ovarian tissue from postmenopausal women between the ages of 50 and 75. This large-scale molecular census allowed the researchers to track how protein abundance shifts across the postmenopausal decades and to search for consistent patterns using multiple types of statistical analysis, rather than relying on any single analytical lens.

The picture that emerged was remarkably coherent. Ovaries from younger postmenopausal women carried a heavier complement of proteins involved in maintaining cells and tissue structure, while ovaries from older women showed increasing levels of proteins associated with inflammation, immune activity, and the ongoing breakdown and rebuilding of the extracellular matrix — the scaffolding that surrounds cells. The molecular differences were most pronounced when the researchers compared ovaries from women in their 50s with those from women aged 70 and older. “When we analyzed the data in multiple different statistical ways, what became clear across all these methodologies is that the ovary was not stagnant,” Schilling said. “In fact, over the decades, there were quite dramatic differences in terms of some proteins’ levels would go up with age and some proteins’ levels would go down, which tells us this organ is quite dynamic.”

The aging ovaries also displayed molecular signatures associated with cellular senescence, a state in which aging or damaged cells stop dividing but remain biologically active, secreting inflammatory signals and other molecules that can influence surrounding tissue. Senescent cells have been implicated in a wide range of age-related conditions, and their presence in postmenopausal ovarian tissue adds the ovary to the growing list of organs that appear to accumulate these problematic cell states over time. Taken together, the findings point to what Duncan describes as progressive aging features, in which the ovary seems to gradually lose its original reproductive identity and take on an altogether different biological character.

Human ovarian tissue is notoriously difficult to obtain, which makes the 28 ovaries in this study an unusually valuable scientific resource. The design of the research also matters: rather than comparing young ovaries with old ones across the entire human lifespan — an approach that inevitably conflates pre- and postmenopausal biology — the team deliberately focused on women within a relatively narrow 25-year age window after menopause. This strategy allowed them to isolate molecular changes that continue to unfold specifically during the postmenopausal years, a period of life that has expanded dramatically as women now routinely live for decades beyond the end of their reproductive capacity. Duncan’s group had previously documented similar continued remodeling in the postmenopausal ovaries of mice, and she notes that seeing the same phenomenon across species lends confidence that what they are observing is not a random artifact but a meaningful feature of ovarian biology.

Perhaps the most provocative finding concerns cancer. More than a decade ago, Duncan’s lab was the first to show that as ovaries age, they become increasingly inflamed, fibrotic and stiff — a process resembling scarring in other tissues. Because cancer cells are known to thrive in collagen-rich, stiff environments, her team has long investigated whether such age-related changes might make the ovary more hospitable to malignant cells. The new study offers a molecular view of that same remodeling process later in life: as postmenopausal ovaries aged, structural proteins declined while inflammation-related and tissue-reshaping proteins became more prominent. Although every tissue sample in the study appeared normal and cancer-free, several proteins previously linked to ovarian cancer were more abundant in the aging ovaries, with the strongest signal observed among women in their 60s. The researchers stress this does not mean the ovaries were cancerous or precancerous — only that healthy ovarian aging and ovarian cancer appear to share some of the same underlying biological processes.

Duncan frames the observation in terms of a broader model of cancer development. “It’s not that all postmenopausal women get ovarian cancer, but we know that that fibrotic inflammatory environment is certainly an environment that cancer cells prefer to home in on,” she said. “This is all consistent with the idea that the aging ovary is a potential third hit for ovarian cancer, with the first hit being genetic and the second hit being environmental. So can we target the aging ovary therapeutically to lower the risk of ovarian cancer, or can we develop novel biomarkers of ovarian cancer?” If the aging ovary’s microenvironment does indeed lower the barrier to malignancy, it could open entirely new avenues for prevention — from anti-inflammatory or anti-fibrotic interventions to early-detection markers rooted in the protein changes the study catalogued.

The work also raises a question that few clinicians have had reason to ask: should otherwise healthy ovaries ever be removed after menopause? “The ovary is not just a reproductive organ,” Schilling said. “It really influences how somebody ages because it speaks to all these other organs, such as the brain, and also to the bone, and women after menopause experience often a lot of bone problems. So, we think there is a connection between all these organs.” Duncan puts the stakes even more bluntly, asking whether the ovary might be “the canary in the coal mine in women” — an organ whose aging could set off a cascade of changes throughout the body. Much remains unknown, including whether the postmenopausal ovary’s activity is beneficial or harmful, and whether there is ever a point at which the organ stops helping and starts hurting. “Our data points to progressive aging features in which the ovary appears to lose its original identity and ends up doing something different,” Duncan said. “We do not yet know if there’s ever a point in a woman’s life when this organ is no longer beneficial and it’s actually harmful. These results really point to the need to ask this question.” The researchers emphasize that their findings do not answer whether healthy ovaries should be removed; instead, they open a new frontier of research into how this long-ignored organ shapes women’s health in the decades after reproduction ends.

Subject of Research: Molecular remodeling of the human ovary in the decades after menopause

Article Title: The ovary doesn’t retire after menopause

Article References: The ovary doesn’t retire after menopause. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: ovary, menopause, aging, proteomics, inflammation, fibrosis, ovarian cancer, cellular senescence, tissue remodeling, Northwestern University, Buck Institute, Aging Cell

The research team drew on the UK Biobank Pharma Proteomics Project, which measured 2,916 plasma proteins in more than 44,000 participants using the Olink Explore 3072 platform. From these protein profiles, the scientists built organ-specific aging clocks using elastic net regression, training models to predict chronological age from protein abundance within each organ domain. The difference between predicted biological age and actual chronological age—known as the age gap—served as the key outcome. A positive residual signals accelerated aging in that organ; a negative residual indicates the tissue is biologically younger than expected. In total, 18 organ-specific indices plus one composite index were generated, covering systems from the brain and heart to the thyroid, adrenal glands, and salivary glands.

After linking these aging indices to self-reported birth weight and breastfeeding status, the researchers analyzed fully adjusted models accounting for age, sex, ethnicity, childhood body size, adult body mass index, socioeconomic deprivation, education, smoking, alcohol use, physical activity, and major cardiometabolic diseases. The final analytic samples comprised 21,446 participants for the birth weight analysis and 29,713 for the breastfeeding analysis. The results were striking in their breadth: higher birth weight was associated with slower biological aging across 11 of the organ systems examined, pointing to a systemic rather than organ-isolated effect of fetal growth conditions.

The strongest inverse associations appeared in the digestive tract. Each additional kilogram of birth weight corresponded to lower intestinal aging scores, with similar patterns in the esophagus and stomach. Beyond the gut, higher birth weight was linked to decelerated aging of the immune system, kidneys, liver, salivary glands, thyroid, adrenal glands, skin, and muscle. These findings align with a well-established body of developmental evidence. Low birth weight has previously been tied to impaired intestinal vascular development, reduced nephron endowment in the kidneys, hepatic fat accumulation, and diminished muscle mass—structural constraints established in utero that may quietly accelerate organ decline across the entire lifespan.

Breastfeeding told a more selective story. Being breastfed was associated with slower aging of the intestine and adrenal glands, but—somewhat unexpectedly—with accelerated aging of the thyroid. The intestinal finding is biologically plausible: breast milk is rich in human milk oligosaccharides and immune factors such as secretory IgA, which promote beneficial microbial colonization, strengthen the gut barrier, and suppress low-grade inflammation, all processes that counteract hallmark features of gut aging. The adrenal association may reflect long-term modulation of the hypothalamic–pituitary–adrenal axis, the body’s central stress-regulation system. The thyroid result, the authors caution, remains speculative; variability in iodine and thyroid hormone content of breast milk could theoretically impose metabolic load on the developing gland, but this interpretation requires further study.

Perhaps the most compelling finding emerged when the two exposures were combined. Participants who both weighed more at birth and had been breastfed showed the most favorable aging profiles of any group, with significantly reduced aging indices in the intestine, kidney, liver, adrenal gland, lung, and stomach. The magnitude of the intestinal effect was roughly double that of either exposure alone, hinting at an additive or synergistic relationship between prenatal and postnatal nutritional advantages. Conversely, low-birth-weight infants who were breastfed gained only modest protection, suggesting that breastfeeding can partially mitigate—but cannot fully compensate for—the developmental constraints of restricted fetal growth.

To probe the mechanisms behind these associations, the team conducted causal mediation analyses testing two candidate pathways: systemic inflammation, measured by C-reactive protein, and allostatic load, a composite index of cumulative physiological wear across ten metabolic, cardiovascular, and inflammatory biomarkers. Allostatic load emerged as the dominant mediator. For skin aging, 35.3 percent of the birth weight benefit was attributable to lower cumulative stress burden, with substantial mediation also seen for the adrenal glands (30.5 percent) and thyroid (19.8 percent). Moderate contributions appeared for the salivary glands, kidneys, and intestines, while C-reactive protein mediated a smaller 4.8 percent of the liver effect. Notably, neither mediator explained the breastfeeding associations, suggesting that infant feeding may act through earlier developmental or localized biological pathways rather than chronic stress accumulation.

The study also revealed that early-life advantages do not operate in a social vacuum. Interaction analyses showed that breastfeeding’s protective effects were stronger in women, particularly for brain, pituitary, arterial, and adipose aging, hinting at sex-specific modulation involving lifelong hormonal milieu. The benefits of both exposures were most pronounced among individuals with higher body mass index and, paradoxically, among those living in more favorable socioeconomic circumstances as measured by the Townsend Deprivation Index. This pattern resonates with the cumulative advantage framework in life-course epidemiology: early biological endowment appears to compound over time when paired with supportive later-life environments, while adverse social and behavioral contexts may erode the protective legacy of good early nutrition.

Sensitivity analyses bolstered the robustness of the findings. Adding medication use to the models left the results virtually unchanged, and mutually adjusting for both perinatal exposures preserved the significance of nine of the eleven birth weight associations and the intestinal benefit of breastfeeding. Restricted cubic spline analyses confirmed that the birth weight relationships were approximately linear across the observed range. Still, the authors acknowledge important limitations. Both exposures were self-reported decades after the fact, introducing potential recall bias that would likely bias results toward the null. Breastfeeding was captured as a simple yes-or-no question, precluding analysis of duration or exclusivity, and proteomic aging indices, while scalable, may not fully capture the structural and functional deterioration visible on imaging or histopathology.

Even with these caveats, the study delivers a provocative message: the trajectory of biological aging is shaped, at least in part, by nutritional conditions in the earliest days of life. By integrating developmental origins theory, population-scale proteomics, and mediation analysis within a single framework, the research reframes organ aging not as a process that begins in middle age, but as the culmination of exposures accumulated across the entire life course. If confirmed in prospective cohorts with granular perinatal data, these findings could elevate early-life nutrition—from maternal-fetal health through infant feeding—into a central pillar of healthy-aging policy, alongside the familiar levers of diet, exercise, and smoking cessation pursued in adulthood.

Subject of Research: Associations of birthweight and breastfeeding with proteome-based organ-specific biological aging in the UK Biobank

Article Title: Birthweight and Breastfeeding Shape Patterns of Biological Aging Across Adult Organs

Article References: Wei, W., Qi, X., Cheng, B., Zhao, B., He, D., Hui, J., Feng, J., Cheng, S., Yang, X., Pan, C., Gou, Y., Wen, Y., Liu, H., Jia, Y., Liu, L., & Zhang, F. (2026). Birthweight and Breastfeeding Shape Patterns of Biological Aging Across Adult Organs. Aging Cell, 25(10), Article e70762. https://doi.org/10.1111/acel.70762

Image Credits: AI Generated

DOI: 10.1111/acel.70762

Keywords: biological aging, birth weight, breastfeeding, UK Biobank, proteomics, organ aging, Developmental Origins of Health and Disease, allostatic load, inflammation, life-course epidemiology, Aging Cell, early-life nutrition

The human body contains hundreds of distinct cell types, and every one of them descends from the same fertilized egg, carrying the same genome. What distinguishes a skin cell from a liver cell, or a blood cell from a nerve cell, is not genetic information but the selective reading of that information. During development, cells become committed to specific fates, and under normal circumstances that commitment is irreversible. A blood cell cannot naturally become a nerve cell, and a skin cell cannot become a liver cell. This stability of identity is one of the defining features of multicellular life, and for most of the history of biology it was considered fixed.

That assumption changed with the advent of cellular reprogramming. By introducing a cocktail of transcription factors, researchers can force a mature cell to read a different set of genetic instructions and embark on a different developmental path. Nerve tissue can now be grown from skin cells, an achievement with obvious implications for treating neurodegenerative diseases, where specific populations of neurons are lost and replacement tissue is scarce. The Bonn group, led by Prof. Dr. Oliver Brüstle, director of the Institute of Reconstructive Neurobiology at the University Hospital of Bonn, has been working at this frontier for years. In earlier studies, his team showed that nerve cells produced through such reprogramming can form connections with existing neurons after transplantation into mouse brains, a critical proof of functional integration.

In the new study, the team applied a direct conversion strategy. Using transcription factor cocktails, they transformed red blood cell precursors straight into induced neural stem cells, bypassing the intermediate stage that most reprogramming protocols require. The resulting cells are restricted to the neural lineage, meaning that only brain cells can emerge from them, but they retain the proliferative capacity and developmental potential characteristic of stem cells. According to Brüstle, this direct route was the key to the study’s most striking finding, because it changed not only what the cells became but how quickly they shed the molecular marks of their age.

To measure rejuvenation, the researchers relied on molecular clocks, tools that track chemical modifications to DNA that accumulate in predictable patterns over a lifetime. These modifications, known collectively as epigenetic marks, do not alter the genetic information itself; instead, they influence how frequently particular genes are read. Because the patterns of these marks change in an orderly way as organisms age, they can be used to estimate the biological age of a cell with remarkable precision. When the Bonn team applied these clocks to their reprogrammed cells, the results were dramatic: cells derived from an 80-year-old donor emerged from the process with a molecular age of less than 20 years, a reduction of roughly six decades.

Crucially, the researchers report that this epigenetic reset is not merely cosmetic. As Brüstle notes, the rejuvenated cells actually behave like young cells, adopting the functional characteristics expected of youthful neural stem cells rather than simply displaying young-looking chemical signatures. This distinction matters, because the central question in the field of cellular rejuvenation is whether the erasure of age-related epigenetic marks corresponds to a genuine restoration of youthful function, or whether it is a superficial byproduct of reprogramming. The Bonn results support the former interpretation, at least for this conversion pathway.

What makes the study genuinely novel, however, is not the fact of rejuvenation but its tempo. Rejuvenation during reprogramming had been observed before, but only in two-step protocols, in which a blood cell is first converted into a pluripotent stem cell, a state in which virtually every career path in the body remains open, and that pluripotent cell is then directed to become a neural stem cell. In that conventional approach, rejuvenation happens very rapidly, compressed into the early phase of the conversion, and is therefore difficult to dissect experimentally. The direct conversion used in Bonn unfolded very differently. Because the blood cells were transformed into neural stem cells without passing through the pluripotent stage, the epigenetic clocks were reset gradually, and the researchers were able to track the process for more than 100 days.

This protracted timeline is what transforms the system from a curiosity into a tool. Rejuvenation that extends over weeks rather than days provides an experimental window through which the underlying mechanisms can be observed in real time. As the researchers point out, because the epigenetic clocks are slowly reset over an extended period, the model can be used to test which factors and active substances accelerate or slow down the rejuvenation process. In effect, the slow conversion turns cellular de-aging into something that can be measured, perturbed, and modulated in the laboratory, opening the door to systematic screens for compounds that influence how cells shed their age-related marks.

The implications extend well beyond basic developmental biology, and the Bonn team is explicit about where they see the greatest relevance. Age is the single most important risk factor for neurodegenerative diseases such as Alzheimer’s, and understanding how the aging process is encoded in cells, and how that encoding can be reversed, is central to any long-term strategy for prevention or treatment. A model in which human cells visibly and gradually de-age over months offers neuroscientists a way to ask precise questions about which molecular events accompany the loss of aging signatures, and whether intervening in those events could protect vulnerable cell types in the aging brain.

The research was carried out by groups from the University Hospital of Bonn, the University of Bonn, and RWTH Aachen University, with funding from the European Union’s Horizon 2020 program, the German Research Foundation, and the Federal Ministry of Research, Technology, and Space. The work, published under the title describing protracted fate acquisition and epigenetic de-aging during induced neural stem cell conversion of human blood cells, adds a new dimension to the growing field of cellular reprogramming. It suggests that the road from an aged blood cell to a youthful brain cell can be made long enough to study, and that in that length lies an opportunity: the chance to finally watch, step by step, what it means for a cell to grow young again.

Subject of Research: Direct reprogramming of human blood cells into induced neural stem cells with epigenetic age reversal

Article Title: Researchers transform old blood cells into young brain cells

Article References: Researchers transform old blood cells into young brain cells. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: cellular reprogramming, epigenetic clocks, neural stem cells, aging, red blood cell precursors, induced neural stem cells, neurodegenerative disease, Alzheimer's disease, University of Bonn, Aging Cell, transcription factors, epigenetics

The stakes are considerable. According to the International Diabetes Federation, type 2 diabetes affected 11.1 percent of the global population aged 20 to 74 in 2024, but that figure climbs above 20 percent among people aged 65 to 99. Aging and obesity are the two dominant risk factors for impaired glucose tolerance and type 2 diabetes, and insulin resistance is a central contributor to disease progression. Yet while the beta cell has been exhaustively studied in this context, the alpha cell, which raises blood glucose by triggering hepatic glucose production through glucagon, has remained largely terra incognita in aging research.

To disentangle the effects of aging itself from those of insulin resistance, the team studied 20-month-old male mice divided into two groups based on insulin sensitivity, measured by the QUICKI index, alongside young adult controls. Remarkably, both aged groups, whether insulin sensitive or resistant, developed hyperglucagonemia and showed exaggerated glucagon responses during an arginine tolerance test. Fasting glucagon levels correlated negatively with insulin sensitivity across all animals, indicating that insulin resistance further amplifies the problem, but the core defect emerged with age alone.

Morphological analysis of the pancreas revealed a likely partial explanation: alpha cell area and mass increased progressively in aged animals, with the expansion most pronounced in insulin-resistant mice. This growth did not stem from hypertrophy or new islet formation, since alpha cell size and islet density remained unchanged. Instead, the data suggest an accumulation of long-lived alpha cells formed earlier in life. Intriguingly, alpha cell proliferation actually declined with age, and apoptosis, while remaining very low overall, ticked up slightly in insulin-resistant animals, painting a picture of a slowly expanding, slowly turning-over cell population.

The architecture of the islets themselves also shifted. Insulin-resistant aged mice showed a reduced proportion of insulin-positive cells and an increased percentage of glucagon-positive cells, along with more alpha cells straying from their characteristic position at the islet periphery into the core. Because islet organization is critical for the paracrine signals that regulate hormone secretion, these spatial changes could directly undermine the inhibitory cues that normally restrain glucagon release when glucose is abundant.

Functional testing confirmed that loss of control. In isolated islets exposed to low glucose, which stimulates glucagon secretion, aged cells performed normally. But when the researchers applied the two physiological brakes, high glucose and insulin, islets from insulin-resistant aged mice failed to suppress glucagon significantly, achieving only about 24 percent inhibition with glucose and 28 percent with insulin, compared with roughly 43 and 54 percent in young controls. Patch-clamp recordings showed that voltage-gated potassium and calcium currents and the exocytotic machinery were largely preserved, pointing the finger at impaired glucose sensing, metabolism, or paracrine signaling rather than a generalized secretory failure.

Transmission electron microscopy uncovered the most striking cellular signature: a markedly enlarged endoplasmic reticulum in alpha cells from both aged groups, a classic hallmark of ER stress. The secretory granules themselves appeared largely normal in number, density, and maturation, though insulin-resistant mice showed slightly larger granules and fewer docked at the membrane, possible signs of early exhaustion from compensatory hypersecretion. Reanalysis of single-cell RNA sequencing data from more than 300,000 islet cells reinforced the finding, revealing upregulated expression of ER stress and unfolded protein response genes, including Hspa5, Atf6, Ddit3, and Xbp1, in alpha cells from old mice. Immunostaining confirmed increased BiP protein in aged alpha cells.

Notably, this ER stress appears adaptive rather than lethal. Unlike beta cells, which lose function under chronic ER stress, aged alpha cells retained their secretory capacity at stimulatory glucose concentrations and showed apoptosis rates of only about 0.1 to 0.2 percent. Recent work suggests ER stress in alpha cells can even enhance glucagon release. The researchers also detected moderate erosion of alpha cell identity: the proportion of glucagon-positive cells expressing the master regulator Arx declined modestly, and insulin-resistant aged mice showed a higher frequency of rare bihormonal cells producing both insulin and glucagon, echoing observations in insulin-resistant humans and elderly rhesus monkeys.

Crucially, the mouse findings translated to humans. Within the CORDIOPREV clinical study, the team analyzed 462 patients without diabetes at baseline, of whom 107 developed type 2 diabetes over a median follow-up of 60 months. Older adults with insulin resistance, whether classified by biological age using telomere length or by chronological age, displayed significantly higher fasting glucagon levels and a greater glucagon secretory response during an oral glucose tolerance test than any other group. Kaplan-Meier analysis showed that while age alone already conferred a significant risk of developing diabetes, elevated glucagon levels amplified that risk further.

The study’s authors caution that several questions remain, including how systemic factors such as inflammation, senescence-associated secretory signals from neighboring beta cells, and altered paracrine regulation integrate with intrinsic alpha cell aging. But the central message is clear: alpha cells are resilient survivors of aging that paradoxically become a metabolic liability, pumping out glucagon when the body can no longer rein them in. As glucagon signaling emerges as a therapeutic target in type 2 diabetes, older adults with insulin resistance may represent the population that stands to benefit most from treatments aimed at restoring the brake on these wayward cells.

Subject of Research: Effects of aging on pancreatic alpha cell function, glucagon secretion, and age-associated type 2 diabetes risk

Article Title: Aging Affects Pancreatic α‐Cell Function and Promotes Hyperglucagonemia: Implications in Age‐Associated Diabetes

Article References: Tudurí, E., Almagro, L., Ojeda‐Rodríguez, A., Pascua‐Maestro, R., Brunetta, H. S., Soriano, S., López‐Moreno, A., Boronat‐Belda, T., Velasco‐Avilés, S., da Silva Junior, J. A., Castellano‐Muñoz, M., Rafacho, A., Cózar‐Castellano, I., Nadal, Á., Alonso‐Magdalena, P., Merino, B., López‐Miranda, J., & Quesada, I. (2026). Aging Affects Pancreatic α‐Cell Function and Promotes Hyperglucagonemia: Implications in Age‐Associated Diabetes. Aging Cell, 25(10), Article e70753. https://doi.org/10.1111/acel.70753

Image Credits: AI Generated

DOI: 10.1111/acel.70753

Keywords: pancreatic alpha cells, glucagon, aging, type 2 diabetes, insulin resistance, hyperglucagonemia, endoplasmic reticulum stress, islet architecture, CORDIOPREV study, beta cells, glucose homeostasis, Aging Cell

The rationale for the work begins with a paradox. Fisetin, a naturally occurring flavonoid found in strawberries and other plants, has shown promise in preclinical studies, reducing senescence markers, alleviating inflammation, and extending healthspan in aged mice. Those findings have fueled multiple clinical trials testing fisetin in chronic kidney disease, osteoarthritis, skeletal health, COVID-19, and frailty. Yet fisetin is, by the authors’ own measurements, not a strong senolytic. It requires high doses in cell culture to kill senescent cells, and it suffers from poor solubility and absorption, properties that could limit its clinical effectiveness. The team set out to fix these weaknesses without abandoning the flavonoid scaffold entirely.

Because fisetin is promiscuous—activating or suppressing a wide range of pathways involved in antioxidant defense, apoptosis, proliferation, inflammation, and angiogenesis—traditional structure-based drug design, which depends on a predefined protein target, was poorly suited to the problem. Instead, the researchers turned to phenotypic drug discovery, screening compounds for their ability to change a visible cellular phenotype: the activity of senescence-associated beta-galactosidase, a classic marker of senescent cells. Using a high-content fluorescent imaging platform, they screened a focused library of natural flavonoids spanning flavones, flavonols, flavanols, anthocyanidins, and other subclasses in senescent mouse embryonic fibroblasts lacking the DNA repair protein ERCC1, alongside matched non-senescent controls.

The screening results were revealing. Fisetin showed only moderate senolytic activity, with an EC50 of roughly 22.74 micromolar and a low selectivity index of 1.53, meaning it was barely more toxic to senescent cells than to healthy proliferating ones. Luteolin, a flavone found in many vegetables, emerged as the most potent and selective natural flavonoid in the screen, with an EC50 of 14.21 micromolar. From these data, the team extracted preliminary structure–activity relationship rules: planar scaffolds retaining the C2–C3 double bond and C4-oxo group of flavones and flavonols were consistently active, while isoflavones, flavanones, and anthocyanidins were largely inert. A 3′,4′-dihydroxyl pattern on the B ring proved essential, a 5-hydroxyl on the A ring hurt activity, electron-donating methoxy groups helped, and any glycosylation was detrimental.

Armed with these guidelines, the researchers launched an iterative cycle of design, synthesis, and biological testing, ultimately creating 35 novel flavonoid analogs. Most outperformed both fisetin and luteolin. Substituents at the 6-position of the A ring proved more favorable than those at the 7-position, and bulky groups such as tert-butyl and isopropyl markedly enhanced activity. Two leads emerged. SR29384, bearing an isopropyl substituent, was the most selective compound in the entire series. SR31133, carrying a five-membered alicyclic ring, was the most potent, with an EC50 of 0.8 micromolar—a more than 27-fold improvement in senolytic activity over fisetin. Both analogs also showed improved computed drug-like properties, including greater lipophilicity, lower topological polar surface area consistent with better blood–brain barrier permeability, and reduced predicted toxicity and carcinogenicity, though the authors caution that such in silico predictions require empirical longitudinal validation.

The optimized analogs proved to be broad-spectrum senolytics. They reduced the number of senescent cells across a diverse panel of models, including Ercc1-deficient fibroblasts, wild-type fibroblasts stressed by oxidative or genotoxic damage, senescent human IMR90 lung fibroblasts, and replicatively senescent human umbilical vein endothelial cells. Treatment also significantly downregulated key senescence and inflammatory markers, including p16Ink4a, p21Cip1, and interleukin-6, outperforming fisetin. Notably, a DPPH radical scavenging assay showed that all three compounds had comparable antioxidant activity, indicating that the enhanced senolytic power of the new analogs was not simply a matter of better antioxidant chemistry but reflected genuinely altered interactions with cellular targets.

The in vivo results were the most striking. In 28-month-old wild-type C57BL/6J mice—an age at which fisetin would not be expected to be significantly effective—the team administered a deliberately low dose of 20 milligrams per kilogram per day for five consecutive days, a stringent comparison against the 100 milligrams per kilogram used in earlier fisetin studies. Fisetin had only marginal effects on senescence and SASP markers. The two analogs, particularly SR29384, significantly decreased expression of p16Ink4a and p21Cip1 as well as multiple SASP factors, including Il6, Il1β, Mcp1, and Pai1, in tissues including kidney, brain, lung, spleen, fat, and muscle. The systemic reduction of senescence markers in diverse organs, including the brain, served as functional evidence that the compounds possess sufficient oral bioavailability to engage their targets, even though direct pharmacokinetic measurements were not performed.

SR29384 was then tested in Ercc1-deficient progeroid mice, a model of accelerated aging. Treated three times per week for five weeks at 20 milligrams per kilogram by oral gavage, the compound suppressed the composite score of aging symptoms, with particularly notable improvements in dystonia and ataxia, two indicators of aging-related neurodegeneration. Gene expression analysis showed significant reductions or trends toward reduction in senescence and SASP factors across the kidney, liver, lung, and brain. The authors note that the effects were tissue- and marker-dependent, and that SR29384 did not show uniform superiority across all tissues, an honest caveat that underscores the complexity of translating senolytic activity from cell culture to living organisms.

Perhaps the most scientifically valuable contribution of the study is its mechanistic dissection. By integrating bulk RNA sequencing, machine-learning-based pathway prediction, structure-based target prediction, protein–protein interaction network analysis, and molecular docking, the team converged on PARP1 and CDK2 as the key shared targets of both analogs, with BCL-xL implicated as a possible third. Docking simulations suggested that both analogs bind the PARP1 catalytic cavity more strongly than fisetin, which suffered unfavorable donor–donor clashes with key residues, and that they compete with ATP in the CDK2 activation domain. Enzyme assays confirmed these predictions: SR31133 inhibited PARP1 with an IC50 of 2.51 micromolar, outcompeting the standard inhibitor 3-AB, and inhibited CDK2 with an IC50 of 12.73 micromolar. Neither analog directly inhibited BCL-xL at the concentrations tested, suggesting that the observed perturbation of BCL-xL signaling networks occurs indirectly. Supporting the functional relevance of these targets, the PARP1 inhibitor olaparib reduced SASP gene expression and modestly reduced SA-β-gal positivity in senescent IMR90 cells, while the CDK2 inhibitor staurosporine reduced SASP genes and p16Ink4a expression.

The proposed mechanism is a multi-hit assault on the pro-survival machinery of senescent cells. Senescent cells resist apoptosis through upregulated anti-death pathways, and the new analogs appear to exploit this vulnerability by disrupting DNA damage detection through PARP1 inhibition, interfering with cell cycle and stress signaling through CDK2, and potentially undermining BCL-xL-mediated survival through crosstalk among these proteins. The two compounds also showed distinct secondary profiles: SR29384’s exclusive targets were enriched for inflammatory signaling and extracellular matrix remodeling, which may explain its remarkable selectivity, while SR31133’s exclusive targets pointed toward histone deacetylation processes. The authors emphasize that formal pharmacokinetic, tissue-distribution, and target-engagement studies are needed next, and that the compounds remain preclinical. Still, by pairing a phenotypic screening platform with modern computational biology, the study demonstrates how an aging-related natural product with murky mechanisms can be transformed into rationally optimized drug candidates—and brings the field a step closer to senotherapeutics that could one day treat multiple age-related diseases at once.

Subject of Research: Development of novel flavonoid senolytic drugs that clear senescent cells and improve healthspan markers in mouse models of aging

Article Title: Novel Flavonoid Senotherapeutics Identified by Phenotypic Drug Discovery Reduce Senescence and Improve Multiple Markers of Healthspan

Article References: Zhang, L. J., Salekeen, R., Soto‐Palma, C., Wu, Q., He, Y., Elsallabi, O., Bdiri, B., Hughes, B., Nunes, A., Xu, W., Zhang, B., Mohamed, A., McGowan, S. J., Angelini, L., O'Kelly, R., Kamenecka, T. M., Niedernhofer, L. J., & Robbins, P. D. (2026). Novel Flavonoid Senotherapeutics Identified by Phenotypic Drug Discovery Reduce Senescence and Improve Multiple Markers of Healthspan. Aging Cell, 25(10), Article e70736. https://doi.org/10.1111/acel.70736

Image Credits: AI Generated

DOI: 10.1111/acel.70736

Keywords: senolytics, cellular senescence, fisetin, flavonoids, SASP, PARP1, CDK2, phenotypic drug discovery, healthspan, aging, Aging Cell, preclinical

The research team, led by investigators at Fujian Medical University, began with a straightforward clinical observation. Analyzing serum samples from three groups of ten participants each—healthy controls, COPD patients without sarcopenia, and COPD patients with sarcopenia—they found that TNF-α stood out as one of the most significantly upregulated cytokines in the sarcopenic group. To model the disease in animals, the researchers exposed mice to cigarette smoke for 24 weeks and added two weeks of hindlimb unloading at the end, a two-hit design that reproduces both the chronic inflammatory burden of COPD and the physical deconditioning that advanced patients experience when breathlessness forces them into inactivity. These Se-Copd mice showed clear pulmonary inflammation, shrunken muscle fibers with a leftward shift in fiber size distribution, and dramatically elevated TNF-α both in serum and in gastrocnemius muscle tissue, confirming that the model faithfully captured the human phenotype.

With the clinical and animal foundations in place, the team turned to high-throughput RNA sequencing to discover what TNF-α actually does inside muscle cells. They treated C2C12 mouse myoblasts with the cytokine and profiled the resulting changes in gene expression. Principal component analysis cleanly separated treated from untreated cells, and pathway enrichment analysis delivered a striking result: the p53 signaling pathway, famous as the genome’s guardian and a central hub of cellular stress responses, was strongly activated among the differentially expressed genes. Both KEGG enrichment and gene set enrichment analysis confirmed the pattern. Among the genes responding to TNF-α, one stood out for its peculiar biochemistry: Prodh2, a mitochondrial enzyme that degrades hydroxyproline and, in doing so, directly generates mitochondrial reactive oxygen species.

Prodh2 had never before been implicated in skeletal muscle disease, making it a genuinely unexplored territory. The enzyme occupies a unique intersection of metabolism, oxidative stress, and signal transduction. Its catalytic reaction is an established source of mitochondrial superoxide, and the Prodh2 gene is a known transcriptional target of p53, the very pathway that TNF-α had just been shown to activate. The researchers confirmed that TNF-α treatment raised Prodh2 mRNA and protein levels in myoblasts in a dose-dependent fashion, with cellular damage rising in parallel as concentrations climbed from 5 to 20 nanograms per milliliter. The question then became whether Prodh2 was merely a bystander or the actual engine of destruction.

The answer came from a series of knockdown experiments that proved decisively that Prodh2 is necessary for nearly everything TNF-α does to muscle cells. When the researchers silenced Prodh2 with siRNA and then exposed the cells to the cytokine, the catastrophic cascade simply failed to launch. Mitochondrial ROS production, measured with MitoSox Red fluorescence, was blunted. The collapse of mitochondrial membrane potential, tracked by the JC-1 dye that shifts from red aggregates to green monomers as mitochondria fail, was prevented. The phosphorylation of the signaling molecules STING, IRF3, and p53 was abrogated. Cytoplasmic release of mitochondrial DNA, a hallmark of mitochondrial damage, was reversed. Cytotoxicity measured by lactate dehydrogenase release, apoptosis detected by TUNEL staining and cleaved caspase-3, and the suppression of proliferation measured by EdU incorporation were all rescued. Even the upregulation of the atrophy genes Atrogin-1 and MuRF1 vanished, and myotubes that would otherwise have shortened dramatically under TNF-α treatment retained their normal length.

To map the complete signaling chain, the team deployed a pharmacological toolkit. The p53 inhibitor Pifithrin-α completely blocked TNF-α’s ability to induce Prodh2 transcription, establishing that the cytokine upregulates the enzyme through p53-dependent transcription. Scavenging mitochondrial ROS with MitoTEMPO rescued cells from mitochondrial stress, proliferation arrest, apoptosis, and myotube atrophy, confirming that reactive oxygen species are the proximate mediators of the damage. Most remarkably, when the researchers overexpressed Prodh2 in cells whose p53 had been pharmacologically inhibited, the phosphorylation of STING and IRF3 returned, causally linking this single metabolic enzyme to the innate immune machinery. The pathway, in essence, runs in a straight line: TNF-α activates p53, p53 drives Prodh2 expression, Prodh2 floods mitochondria with ROS, damaged mitochondria release their DNA into the cytoplasm, and that mislocalized DNA triggers the cGAS/STING innate immune pathway.

This final step carries particular significance for the biology of aging. Mitochondrial DNA, being of prokaryotic origin, is recognized by the cytosolic DNA sensor cGAS as a danger signal when it escapes its organelle, provoking a type I interferon response and what researchers call sterile inflammation. Aberrant activation of this mtDNA-cGAS/STING axis has been implicated in renal fibrosis, atherosclerosis, cerebral ischemia-reperfusion injury, and, critically, in the chronic low-grade inflammation of aging known as inflammaging. Recent work has shown STING activation in muscle wasting associated with cirrhosis and COPD-related muscle senescence, but the upstream trigger inside muscle cells had remained mysterious. By identifying Prodh2-mediated ROS production as the initiator of mtDNA release, the study provides the first complete molecular answer to how metabolic dysregulation ignites innate immunity to drive sarcopenia.

The findings also cast p53 in an unexpected and darker role. Best known as a tumor suppressor, p53 has increasingly been recognized as a context-dependent driver of pathology in noncancerous diseases, promoting senescence and tissue dysfunction in neurodegeneration, skin aging, and ischemia-reperfusion injury when activated by chronic rather than acute stress. The study’s authors note that while earlier work in cancer cell lines found Prodh2 to be at best a weak p53 target under acute genotoxic stress, the robust induction they observed in myoblasts reflects a fundamentally different biological context: chronic inflammatory signaling through TNF-α, likely engaging distinct transcriptional co-factors or epigenetic states that render the Prodh2 promoter highly responsive in muscle progenitor cells.

Crucially, the team then asked whether blocking Prodh2 could treat the disease in living animals. Using adeno-associated viruses carrying shRNA injected directly into the gastrocnemius muscles of Se-Copd mice, they achieved targeted knockdown of the enzyme over a 12-week intervention period. The results were striking: treated mice recovered significant grip strength, their muscle fiber cross-sectional areas increased, atrophy markers Atrogin-1 and MuRF1 declined, and phosphorylation of p53, IRF3, and STING in muscle tissue was suppressed. Immunohistochemistry revealed that Prodh2 was diffusely overexpressed throughout the cytoplasm of mature contractile myofibers in the diseased animals, indicating that the pathway operates universally in muscle tissue under chronic inflammatory stress. Importantly, knocking down Prodh2 did not lower the animals’ serum TNF-α levels, demonstrating that the intervention works downstream of inflammation, at the point where inflammatory signals are translated into mitochondrial catastrophe.

The authors acknowledge limitations, including the lack of cell-type specificity in the AAV vector and the absence of histological data from other muscles such as the diaphragm, and they plan cell-specific Cre-LoxP studies to dissect the contributions of progenitors versus mature fibers. Nevertheless, the study delivers a complete mechanistic arc from clinic to molecule to therapy. It establishes a metabolic-immune crosstalk framework for sarcopenia in which a chronic inflammatory cytokine, acting through the ancient stress hub p53, repurposes a ordinary mitochondrial enzyme into an engine of self-destruction. In doing so, it positions Prodh2 as a druggable upstream node, offering hope that future interventions could protect the muscles of millions of COPD patients even while the inflammation itself continues to smolder in their lungs.

Subject of Research: The role of Prodh2-mediated mitochondrial stress in TNF-α-induced myoblast dysfunction and sarcopenia in COPD

Article Title: Prodh2‐Mediated Mitochondrial Stress Drives TNF‐α‐Induced Myoblast Dysfunction and Sarcopenia in COPD

Article References: Chen, G., Shangguan, Z., Gong, J., Cheng, D., Chen, P., Li, J., & Lin, Q. (2026). Prodh2‐Mediated Mitochondrial Stress Drives TNF ‐α‐Induced Myoblast Dysfunction and Sarcopenia in COPD. Aging Cell, 25(10), Article e70739. https://doi.org/10.1111/acel.70739

Image Credits: AI Generated

DOI: 10.1111/acel.70739

Keywords: COPD, sarcopenia, TNF-alpha, Prodh2, mitochondrial ROS, p53, STING, mitochondrial DNA, muscle atrophy, inflammation, myoblasts, Aging Cell

The biological problem the researchers set out to tackle is well known to reproductive medicine. As women age, the quality of their oocytes deteriorates, driving up rates of miscarriage, chromosomal abnormalities, preterm birth and fetal growth restriction, and making women aged 35 to 39 more prone to infertility than any other age group. Oocyte quality hinges on two tightly coordinated processes: nuclear maturation, in which chromosomes separate during the resumption of meiosis, and cytoplasmic maturation, in which the egg stockpiles the messenger RNAs, proteins and substrates that fertilization and early embryonic development will demand. Aging disrupts the cytoplasmic arm of this program through mitochondrial dysfunction, disturbed calcium signaling, malformed smooth endoplasmic reticulum and cytoskeletal disarray.

Mitochondria sit at the center of that failure. The oocyte is one of the most energy-hungry cells in the body, relying on oxidative phosphorylation through the five complexes of the electron transport chain to power chromosome segregation, spindle migration and organelle repositioning. In aging oocytes, the respiratory capacity of each mitochondrion falls and the mitochondrial membrane potential drops, a shift typically accompanied by a surge in reactive oxygen species. That oxidative burst damages nuclear and mitochondrial DNA, destabilizes the meiotic spindle and can ultimately produce aneuploid eggs. Previous metabolic surveys of aging ovaries found depletion of NAD+, purines and pyrimidines alongside an accumulation of glycolysis substrates and glutamine, painting a consistent picture of failing mitochondrial metabolism.

Researchers have tried a succession of interventions to prop up the aging egg: the CD38 inhibitor 78c to raise NAD+ levels, rapamycin to restore protein homeostasis, melatonin to quench oxidative stress, spermidine to enhance mitophagy, and mitochondria-targeted antioxidants such as MitoQ and SkQ1, along with NAD+ boosters like nicotinamide mononucleotide and the electron carrier CoQ10. Each has shown promise, but low targeting efficiency and poor bioavailability have limited clinical translation. Elamipretide, a membrane-penetrating aromatic cationic tetrapeptide with the sequence Arg-Dmt-Lys-Phe-NH2, was attractive to the team precisely because it is small, water-soluble, resistant to peptidase degradation and stable in solution—properties that make it a plausible candidate for real-world clinical use.

The peptide’s mechanism is unusually specific. At physiological pH it carries three positive charges and accumulates in the inner mitochondrial membrane through electrostatic and hydrophobic interactions, where it binds with high affinity to cardiolipin, a signature phospholipid of that membrane. Cardiolipin is central to respiratory chain supercomplex assembly, membrane stability and energy transduction, but it is also vulnerable to oxidation under oxidative stress, which disrupts the membrane, saps electron transport efficiency and diminishes ATP output. By binding cardiolipin, elamipretide inhibits the peroxidase activity of cytochrome c, prevents cardiolipin oxidation and preserves the cristae architecture of the inner membrane, stabilizing energy production and cutting back the generation of reactive oxygen species.

To test whether these properties could rescue the aging ovary, the team treated 10-month-old mice—well past the mouse reproductive prime—with daily intraperitoneal injections at 3, 5 or 10 milligrams per kilogram. The 5 mg/kg dose proved optimal, and a seven-day course was the most effective duration, improving reproductive performance in 8-, 10- and 12-month-old animals with the strongest gains in the 10-month group. Ovarian sections showed a marked increase in high-quality dominant follicles, fertilization rates of aged oocytes rose substantially, and early embryonic development recovered: aged oocytes normally stall between the two-cell and four-cell stages after fertilization, but elamipretide effectively reversed that block. The benefit, however, was transient, lasting only about a month, which the authors note defines both the promise and the limits of the regimen.

Molecular profiling revealed an unexpected metabolic handle on the effect. Metabolomics of treated ovaries showed that elamipretide shifted the aged metabolome back toward a young-like profile, and pathway analysis singled out vitamin B6 metabolism as the most dramatically altered route. When the team supplemented aged oocytes directly, vitamin B6—but not the other strongly altered metabolites, L-acetylcarnitine and aminovaleric acid—fully reversed the age-associated decline in first polar body extrusion, the hallmark of successful nuclear maturation. Transcriptomics then pointed to the vascular endothelial growth factor pathway, whose age-elevated expression was normalized by the peptide. Blocking VEGF-A transcription with the inhibitor PTC299 reproduced many of elamipretide’s benefits in aged oocytes, restoring mitochondrial positioning, damping the ROS surge, repairing spindle defects and correcting chromosome misalignment, while PI3K/AKT inhibitors failed to do so—placing VEGF-A, acting downstream of vitamin B6 metabolism, at the heart of the mechanism.

Under the microscope, the cellular rescue was striking. Aged oocytes typically display aberrant spindles and scattered chromosomes, loss of γ-tubulin foci at the spindle poles, and reduced acetylation of tubulin, a marker of microtubule instability. Elamipretide restored all of these, along with the cytoplasmic actin network that aging disrupts, and it recovered the expression of ROCK1/2, proteins involved in actin assembly. Mitochondria, which drift away from the spindle and clump in the cytoplasm of aged eggs, returned to their proper peri-spindle domain; ATP levels normalized, mitochondrial DNA copy number partially rebounded, membrane potential rose and ROS fell. The peptide also repaired organelle systems beyond the mitochondria: Golgi markers Rab10 and GM130, endoplasmic reticulum positioning and the ER stress marker GRP78, lysosomal distribution and LC3-mediated autophagic flux all returned toward youthful patterns, indicating a coordinated restoration of cytoplasmic maturation.

Crucially, the findings were not confined to mice. In a randomized in vitro experiment approved under the Declaration of Helsinki, germinal vesicle oocytes from 39 patients undergoing intracytoplasmic sperm injection were cultured with or without 500 micromolar elamipretide. Among women aged 35 and older—three patients contributing 54 oocytes—the peptide improved maturation at both 24 and 48 hours and raised fertilization and cleavage rates after ICSI, with similar gains in younger women’s oocytes. In pigs, whose oocytes are a standard translational model, elamipretide at 1 millimolar rescued maturation in eggs subjected to hydrogen-peroxide-induced oxidative stress, restoring mitochondrial distribution, LC3 expression and apoptosis levels. The authors conclude that short-term elamipretide treatment reverses age-related oocyte decline through a vitamin B6–VEGF axis that jointly rescues nuclear and cytoplasmic maturation. Because the peptide has already advanced into human trials for cardiac and neuromuscular indications, the path from mouse ovary to fertility clinic may be shorter than for most laboratory discoveries—though the transient one-month window of benefit and the small human sample mean considerable work remains before any clinical application.

Subject of Research: Mitochondria-targeted peptide therapy for age-related decline in oocyte quality and female fertility

Article Title: Elamipretide Rejuvenates Oocyte Quality and Restores Female Fertility During Reproductive Aging

Article References: Zhang, H.-L., Wang, Y., Wang, C., Guo, X., Chen, H., Hou, Y.-X., Wu, X., Wu, Z.-J., Pan, W.-L., Ma, R.-J., Lu, P.-S., Shu, J., & Sun, S.-C. (2026). Elamipretide Rejuvenates Oocyte Quality and Restores Female Fertility During Reproductive Aging. Aging Cell, 25(10), Article e70749. https://doi.org/10.1111/acel.70749

Image Credits: AI Generated

DOI: 10.1111/acel.70749

Keywords: elamipretide, oocyte aging, female fertility, mitochondria, cardiolipin, vitamin B6, VEGF, oxidative stress, meiotic spindle, reproductive aging, in vitro maturation, Aging Cell

The study, led by investigators at Shanxi Medical University, tackled a long-standing puzzle in cardiac aging research. Scientists have known that mitochondria, the power plants of the cell, deteriorate as hearts grow old. But the precise mechanism linking that deterioration to the broader decline of the aging myocardium has remained elusive. Because natural aging in mice takes many months and carries high mortality, the team used doxorubicin, a chemotherapy drug well established to produce cardiac damage that closely mimics natural cardiac aging, including mitochondrial dysfunction, enlargement of individual cardiomyocytes, and weakened contraction. They treated young male C57BL/6J mice with repeated low doses of the drug, building up a cumulative regimen that reliably induced senescence in heart tissue.

The first major finding concerned a process called mitophagy, the specialized form of autophagy that clears out damaged mitochondria. Under normal conditions, worn-out mitochondria are tagged, engulfed by autophagosomes, and delivered to lysosomes for degradation, keeping the mitochondrial network healthy. In the aging hearts, electron microscopy revealed a striking accumulation of mitophagosomes—structures that had captured damaged mitochondria but were never processed further. Levels of the autophagy marker LC3B-II and the cargo receptor p62 were simultaneously elevated, a classic signature of a blocked degradative pathway. When the researchers applied chloroquine, a drug that halts lysosomal degradation, to young cells, mitochondrial–LC3B colocalization rose sharply; in aged cells, the drug produced no further increase, indicating that the degradative arm of mitophagy was already saturated. In other words, the aging heart was not failing to initiate mitophagy—it was failing to finish it, creating a traffic jam of half-processed cellular garbage.

The consequences of this congestion were visible throughout the senescent cardiomyocytes. Live-cell imaging showed mitochondria that were shorter, rounder, and more fragmented than those in healthy cells, with fewer branch points and reduced network integrity. Flow cytometry using the MitoSOX probe revealed a significant surge in mitochondrial superoxide, a reactive oxygen species generated by dysfunctional mitochondria. Energy production faltered, oxidative stress mounted, and the senescence program advanced: senescence-associated beta-galactosidase activity climbed, and the proteins p16 and apolipoprotein E—well-established markers of cellular aging—rose in both the mouse hearts and in HL-1 cardiomyocytes treated with doxorubicin in culture.

Enter the therapy. The team isolated mitochondria from murine bone marrow mesenchymal stem cells, a source chosen for its regenerative potential and shared mesodermal origin with cardiomyocytes, and delivered them through the tail vein at 0.5 milligrams per kilogram every two days for six injections. Fluorescent tracing with MitoTracker-labeled mitochondria, monitored by whole-body imaging over 24 hours, confirmed that the organelles reached the cardiac region, and time-lapse microscopy captured them entering cardiomyocytes in culture. The results were dramatic. Echocardiography showed significant recovery of left ventricular fractional shortening and ejection fraction, along with reduced end-systolic volume. Wheat germ agglutinin staining revealed smaller, less hypertrophied cardiomyocytes, senescence staining dropped markedly, and electron microscopy showed fewer mitophagosomes, more intact mitochondria, and restored cristae density. Superoxide levels fell, and the senescence markers p16 and APOE declined in both tissue and cultured cells.

To find the molecular switch behind this rejuvenation, the researchers turned to multi-omics. RNA sequencing of aged versus young hearts identified 27 differentially expressed mitochondrial genes, and one stood out: Bnip3, which encodes an atypical BCL-2 family protein embedded in the mitochondrial outer membrane. BNIP3 normally acts as a mitophagy receptor, recruiting the autophagosome marker LC3B through its LC3-interacting region to initiate mitochondrial clearance. In the aging heart, BNIP3 was dramatically overexpressed, and its expression correlated far more strongly with the autophagy marker Map1lc3b than did PINK1, the canonical ubiquitin-dependent mitophagy pathway, whose Parkin protein levels were unchanged. Crucially, the pattern was conserved across species: hearts from 80-week-old naturally aged mice showed elevated BNIP3, and single-cell RNA sequencing of human heart datasets from GSE156703 and the Heart Cell Atlas revealed significantly higher BNIP3 expression in aged human cardiomyocytes.

Functional experiments confirmed that BNIP3 was not merely a bystander but a driver of senescence. When the researchers forced BNIP3 overexpression in HL-1 cardiomyocytes, the cells developed the full senescent phenotype—elevated p16 and APOE, increased beta-galactosidase staining, and rising levels of LC3B-II and p62 that signaled autophagic congestion. Conversely, when BNIP3 was overexpressed in cells that had received mitochondrial transplantation, the therapy’s benefits vanished: senescence staining returned to aged levels, LC3B–mitochondria colocalization climbed back up, and the accumulated autophagy proteins reappeared. This reversal experiment demonstrated that downregulation of BNIP3 is essential for mitochondrial transplantation to work.

The upstream regulator proved to be an unexpected player. Screening transcription factors altered in the aging heart, the team identified HIF-3α, the least-studied member of the hypoxia-inducible factor family, long regarded mainly as a transcriptional repressor. Here it acted as an activator. Bioinformatic prediction with JASPAR revealed a high-affinity HIF-3α binding site in the Bnip3 promoter, dual-luciferase reporter assays confirmed that HIF-3α could drive Bnip3 transcription, and chromatin immunoprecipitation followed by quantitative PCR pinned down the binding at a specific promoter site. Overexpressing HIF-3α raised BNIP3 levels; silencing it with siRNA lowered them. HIF-1α, the family’s famous member, showed no significant changes, indicating a distinct, non-redundant pathway. HIF-3α was also elevated in aged mouse hearts and aged human cardiomyocytes, and clinical data from heart failure samples in prior literature align with the axis’s upregulation.

Perhaps the most provocative discovery concerns what HIF-3α actually senses: energy. When the researchers measured ATP, they found that mitochondrial transplantation markedly boosted energy levels in aged cardiac tissue. To test whether ATP fluctuations drive the axis, they treated cardiomyocytes with CCCP, a chemical that collapses mitochondrial membrane potential and depletes ATP. ATP levels fell, and HIF-3α rose in response. The emerging model is elegant: as the aging heart’s mitochondria falter and ATP production drops, the energy crisis stabilizes HIF-3α, which switches on BNIP3, floods the cell with mitophagy receptors, and jams the mitophagy flux. Transplanting fresh mitochondria restores ATP, HIF-3α and BNIP3 subside, and the disposal system flows freely again.

The findings arrive as mitochondrial transplantation itself moves into early clinical exploration. Phase I trials in pediatric ischemia-reperfusion injury have already demonstrated preserved cardiomyocyte viability, and systematic reviews support the approach’s potential to restore myocardial bioenergetics, with encouraging safety data showing no immune responses after autologous transplantation. Significant questions remain before aging hearts could be treated this way: the precise mechanism by which HIF-3α senses low ATP is still unknown, whether transplanted mitochondria physically fuse with the recipient’s mitochondrial network has not been directly visualized, and no clinical safety evaluations exist for this application. Delivery routes also pose challenges, from the invasiveness of intramyocardial injection to the low cardiac targeting efficiency of intravenous administration. Still, by identifying the HIF-3α–BNIP3 axis as a druggable control point for mitophagy flux, the study offers something the field has lacked—a concrete molecular explanation for why aging hearts clog their own cleanup machinery, and a demonstration that the clog can be cleared.

Subject of Research: Mitochondrial transplantation therapy for cardiac aging via restoration of mitophagy flux through the HIF-3α–BNIP3 pathway

Article Title: Mitochondrial Transplantation Rejuvenates Aging Heart by Restoring Mitophagy Flux via the HIF‐3α‐BNIP3 Axis

Article References: Jin, N., Zhou, L., Gui, H., Tang, J., Huang, X., Wang, W., Jin, G., Cheng, H., Liang, Y., Geng, X., Peng, Z., Zhao, H., Liu, Z., & Xie, J. (2026). Mitochondrial Transplantation Rejuvenates Aging Heart by Restoring Mitophagy Flux via the HIF ‐3α‐ BNIP3 Axis. Aging Cell, 25(10), Article e70720. https://doi.org/10.1111/acel.70720

Image Credits: AI Generated

DOI: 10.1111/acel.70720

Keywords: mitochondrial transplantation, cardiac aging, mitophagy, BNIP3, HIF-3α, senescence, mesenchymal stem cells, doxorubicin, ATP, autophagy flux, cardiomyocytes, Aging Cell

The investigation began with a straightforward question: is alpha-synuclein actually present in atherosclerotic lesions? The team collected carotid plaque specimens from three patients undergoing endarterectomy and subjected them to liquid chromatography–tandem mass spectrometry. Peptides corresponding to alpha-synuclein were detected in every specimen, and western blotting confirmed the finding, revealing an immunoreactive band just above 15 kilodaltons, the expected size of the monomeric protein, along with higher-molecular-weight species that may represent modified or protein-associated forms. This protein-level validation established that the Parkinson’s-associated protein genuinely inhabits the vascular disease environment rather than merely circulating in the bloodstream at large.

To test whether the protein matters functionally, the researchers turned to mice lacking the Snca gene, which encodes alpha-synuclein. Using an adeno-associated virus carrying PCSK9 followed by sixteen weeks of high-cholesterol diet, they induced atherosclerosis in both knockout animals and wild-type littermates. The results were striking: mice without alpha-synuclein developed significantly smaller lesions across the whole aorta and aortic arch, with reduced plaque area, smaller necrotic cores, and diminished lipid deposition at the aortic root. The phenotype appeared in both sexes, and immunofluorescence analysis pinpointed the difference to macrophage-derived foam cells, identified as cells positive for both the macrophage marker CD68 and the lipid dye BODIPY. Lipid-laden smooth muscle cells, by contrast, were not detectably altered, suggesting the protein’s influence is concentrated on the macrophage arm of plaque biology.

Because alpha-synuclein circulates in blood, largely as monomers carried by red blood cells, the team next asked whether extracellular exposure to the protein could actively worsen disease. They injected purified recombinant alpha-synuclein into atherosclerosis-prone Apoe-deficient mice twice weekly for twelve weeks while the animals consumed a high-cholesterol diet. Compared with controls receiving vehicle, the treated mice showed markedly increased lipid deposition in the whole aorta and aortic arch, larger plaques, expanded necrotic cores, and a higher density of macrophage foam cells within lesions. Collagen content, a measure of plaque stability, did not increase proportionally, implying that the additional lipid burden came with reduced lesion stability. In cell culture, adding alpha-synuclein to macrophages exposed to oxidized low-density lipoprotein further amplified neutral lipid accumulation, while uptake of labeled ox-LDL remained unchanged.

The critical clue came from cholesterol efflux assays. When macrophages pre-loaded with fluorescent NBD-cholesterol were treated with alpha-synuclein, their ability to export cholesterol to both high-density lipoprotein and apolipoprotein A-1 acceptors dropped significantly. Curiously, the protein levels of the classical lipid-handling machinery, including the uptake receptors CD36, MSR1, and OLR1 and the transporters ABCA1 and ABCG1, were unaffected. This pointed the investigators away from transcriptional regulation of lipid traffic and toward the autophagy-lysosome system, the intracellular recycling network that, through a process called lipophagy, delivers lipid droplets to lysosomes for hydrolysis and frees cholesterol for export.

A series of complementary experiments converged on a specific defect: the fusion of autophagosomes with lysosomes. Alpha-synuclein-treated macrophages accumulated the autophagy markers LC3B-II and SQSTM1, a signature of blocked degradation rather than enhanced autophagic activity, since chloroquine pre-treatment eliminated the further LC3B-II increase. Confocal microscopy showed reduced colocalization between lipid droplets and lysosomes, between lipid droplets and LC3, and, most tellingly, between LC3-labeled autophagosomes and LAMP1-labeled lysosomes. Transmission electron microscopy revealed fewer autolysosomal structures and enlarged lipid droplets. Finally, a macrophage line stably expressing the tandem RFP-EGFP-LC3 reporter, in which red-only puncta mark completed autolysosomes and yellow puncta mark stalled autophagosomes, showed a clear shift toward yellow puncta after alpha-synuclein treatment. The autophagy conveyor belt, in short, jammed at the fusion step.

Having localized the blockage, the researchers traced it upstream to signaling. The SNARE proteins that physically mediate autophagosome-lysosome fusion, STX17, SNAP29, and VAMP8, were not reduced in abundance, distinguishing macrophages from neurons, where alpha-synuclein overexpression was previously shown to degrade SNAP29. Instead, alpha-synuclein treatment increased phosphorylation of PI3K and AKT, which in turn activated mTOR and its downstream effectors S6K and ULK1 at the inhibitory Ser757 site, while AMPK phosphorylation remained unchanged. Pharmacological intervention confirmed the pathway’s relevance: pretreatment with the PI3K inhibitor LY294002 blunted the mTOR phosphorylation response, and either LY294002 or the mTOR inhibitor rapamycin normalized LC3B-II accumulation and significantly reduced alpha-synuclein-induced lipid droplet buildup. Blocking this axis, in other words, partially rescues the foam cell phenotype.

The remaining question was how extracellular alpha-synuclein gains entry and triggers PI3K signaling. Proteomic comparison of treated and untreated macrophages flagged flotillin-1, or FLOT1, a membrane raft-associated protein previously implicated in alpha-synuclein endocytosis in dopaminergic neurons. Alpha-synuclein treatment increased FLOT1 protein levels, and silencing Flot1 with siRNA markedly reduced the protein’s uptake into macrophages. Immunofluorescence showed intracellular colocalization between alpha-synuclein and FLOT1, and co-immunoprecipitation supported a biochemical association, though the authors note these assays do not establish direct binding. Functionally, Flot1 knockdown abolished the alpha-synuclein-induced phosphorylation of PI3K, prevented the accumulation of LC3B-II, partially reduced SQSTM1 upregulation, restored HDL-mediated cholesterol efflux, and attenuated foam cell formation. Consistent with the in vitro data, atherosclerotic mice injected with alpha-synuclein carried a higher density of FLOT1-positive macrophages in their plaques.

The study’s authors emphasize that endogenous alpha-synuclein expression in macrophages is extremely low, which likely explains why Snca-deficient macrophages showed no intrinsic defect in foaming capacity in vitro. The atheroprotective phenotype of the knockout mice may instead reflect reduced exposure to circulating, extracellular alpha-synuclein, a hypothesis their injection experiments directly support. This reframing matters because it positions alpha-synuclein not merely as a neuronal liability but as a circulating factor whose peripheral levels, already known to be elevated in Parkinson’s patients, could plausibly influence vascular risk. Epidemiological observations lend circumstantial weight: Parkinson’s disease has been associated with a higher prevalence of carotid plaques and an increased risk of ischemic stroke, and alpha-synuclein has been detected in HDL and lipoprotein(a) fractions as well as in cerebrovascular walls and endothelial cell secretions.

The implications reach into therapeutics. The identification of FLOT1 as a candidate entry mediator and of the PI3K-AKT-mTOR axis as the signaling conduit suggests at least two pharmacologically tractable nodes, both already targeted by existing drugs such as rapamycin. The authors caution that inhibitor effects were partial, that SQSTM1 accumulation also reflects transcriptional upregulation possibly tied to inflammatory signaling, and that the colocalization and co-immunoprecipitation data do not prove direct molecular binding. Nonetheless, the convergence of human plaque proteomics, genetic mouse models, and mechanistic cell biology builds a coherent case that extracellular alpha-synuclein impairs macrophage autophagic flux, stalls cholesterol export, and accelerates atherosclerosis. For aging populations, in which declining autophagy and rising vascular disease already converge, the prospect that a single protein links neurodegeneration and arterial pathology offers both a unifying biological insight and a fresh set of intervention points.

Subject of Research: The role of alpha-synuclein in macrophage autophagic dysfunction and atherosclerosis progression

Article Title: α‐Synuclein Promotes Atherosclerosis by Impairing Macrophage Autophagic Flux

Article References: Qin, M., Xiang, X., Guo, X., Wang, S., Chen, J., Jiang, D., Feng, Y., Yu, J., & Mao, L. (2026). α‐Synuclein Promotes Atherosclerosis by Impairing Macrophage Autophagic Flux. Aging Cell, 25(10), Article e70713. https://doi.org/10.1111/acel.70713

Image Credits: AI Generated

DOI: 10.1111/acel.70713

Keywords: alpha-synuclein, atherosclerosis, macrophages, autophagy, foam cells, FLOT1, PI3K-AKT-mTOR, cholesterol efflux, Parkinson's disease, lipophagy, vascular aging, Aging Cell