KHOSLA, S

Abstract Extensive studies in rodents have shown that senescent cells accumulate across tissues and their clearance leads to improvements in healthspan and lifespan. Based on these studies, there is intense interest in translating these findings into humans. Based on ClinicalTrials.gov, there are currently 26 ongoing studies on “senolytics” and 32 on “fisetin”. However, to date, there are only 9 published clinical trials of senolytics, only 2 of which included a control group. Collectively, the initial findings from these trials have indicated possible biological efficacy of senolytics (dasatinib + quercitin) in improving biomarkers of healthspan in humans with no significant safety concerns. However, these initial studies also highlight the potential heterogeneity of aging mechanisms in humans and argue for a more personalized approach in future senolytic trials. Specifically, it is likely going to be critical to identify aging individuals with a sufficiently high burden of senescent cells that would result in a beneficial effect from the senolytic intervention.

ABSTRACT Objective Aging alters mesenchymal stromal cell (MSC) function, leading to dysregulated adipogenesis across tissues through biased lineage commitment. Fat redistribution from adipose depots to skeletal muscle and bone marrow is common in aging, but the underlying mechanisms remain unclear. This study investigates how MSC senescence modulates adipogenesis. Methods Primary MSCs were isolated from mouse skeletal muscle (FAPs), adipose tissue (APCs), and bone marrow (BMSCs). Single‐cell RNA sequencing was performed to compare transcriptional profiles among these populations. In vitro adipogenic differentiation and DNA damage–induced senescence assays were conducted, and the effects of autologous conditioned media from senescent MSCs on adipogenesis were assessed. Results Transcriptional analyses revealed that FAPs and APCs share greater similarity with each other than with BMSCs. All MSC types exhibited adipogenic potential and developed a robust senescence‐associated secretory phenotype (SASP) upon senescence induction. Conditioned media from senescent MSCs enhanced adipogenesis in BMSCs but inhibited adipogenesis in FAPs and APCs, revealing tissue‐specific paracrine effects. Conclusions MSC senescence reprograms adipogenic bias in a tissue‐dependent, non–cell autonomous manner, contributing to age‐related fat redistribution among adipose tissue, skeletal muscle, and bone marrow. Understanding these mechanisms may provide new therapeutic approaches for improving tissue composition and function in the context of aging.