Mesenchymal stem cell (MSC) therapy

Mesenchymal stem cells (MSCs) are multipotent stromal progenitors capable of differentiating into osteoblasts, chondrocytes, and adipocytes, and are isolated from bone marrow, adipose tissue, umbilical cord (Wharton's jelly), placenta, and dental pulp, with umbilical cord-derived MSCs increasingly favoured for allogeneic use due to lower immunogenicity and higher proliferative capacity. Despite early assumptions of direct tissue engraftment and replacement, current evidence indicates that transplanted MSCs rarely engraft stably at target tissues; instead, the dominant mechanism of action is paracrine, mediated by secreted cytokines, growth factors, extracellular vesicles (exosomes and microvesicles), and mitochondrial transfer, which modulate local immune responses, reduce fibrosis, support angiogenesis, and dampen senescent cell secretome activity. In age-related and chronic disease contexts, MSC therapies have been investigated in clinical trials for osteoarthritis, graft-versus-host disease, Crohn's disease, heart failure, COPD, and frailty, with graft-versus-host disease being the setting with the most established regulatory acceptance in some jurisdictions. For aging and longevity applications specifically, small trials have reported functional improvements in frailty endpoints, but sample sizes, follow-up durations, and outcome standardization remain insufficient for definitive conclusions. Regulatory status varies by region: the EMA and FDA require approval as advanced-therapy medicinal products (ATMPs) or biologics, and many administered products operate outside approved frameworks. Long-term safety data, including oncogenicity risk from repeated dosing, are not fully established.