Translating umbilical cord blood extracellular vesicles into a novel therapy for postpartum alopecia: a mechanistic and preclinical review.

Postpartum alopecia (PPA) is a common physiological hair loss in women, characterized by complex pathogenesis involving abrupt postpartum hormonal withdrawal, disrupted hair follicle cycling, local microenvironmental inflammation, and oxidative stress. Umbilical cord blood-derived extracellular vesicles (UCB-EVs)-nanosized, lipid-bilayer-enclosed particles enriched with microRNAs, growth factors, and proteins-have shown considerable promise in regenerative medicine owing to their low immunogenicity, high biocompatibility, and tissue-repair capacity. This review systematically summarizes the current state of research on UCB-EVs in the context of PPA, focusing on their proposed molecular mechanisms in hair follicle regeneration, hair-cycle modulation, antiinflammatory effects, and antioxidative stress responses. Importantly, the available evidence remains largely preclinical, derived from in vitro and animal-model studies; direct clinical evidence for UCBEVs in PPA is still lacking. UCB-EVs should therefore be regarded as a promising investigational strategy, and their clinical translation will require rigorous validation of standardization, safety, and efficacy.