Stem-Cell Exhaustion, Cellular Rejuvenation and the Translational Frontier of Geroscience: A Structured Critical Evidence Review of Human and Preclinical Interventions Targeting Biological Aging

Background: Aging biology has become experimentally tractable, and private capital has entered the field at a scale without precedent in geriatric medicine.Whether that tractability has produced clinically meaningful human benefit is a separate question.Stem-cell exhaustion is a recognised hallmark of aging, and cell-based, reprogramming-based and vesicle-based products dominate both the scientific and the commercial imagination of the field.Methods: This is a structured critical evidence review with protocol-informed narrative synthesis, not a completed systematic review.Retrieval drew on PubMed/MEDLINE-indexed literature, ClinicalTrials.gov(application programming interface version 2), regulatory and guideline documents, corporate securities filings, retraction registries and citation chaining,