Exosomes and Hair Regeneration: A Systematic Review of Clinical Evidence Across Alopecia Types and Exosome Sources.

Mesenchymal stem cell (MSC)-derived exosomes are recognized a promising cell-free therapy for alopecia. These nano-vesicles facilitate intercellular communication and contain a variety of bioactive molecules that can potentially stimulate hair follicle regeneration. However, the safety and efficacy of exosome therapy for alopecia remains to be determined. This systematic analysis aimed to determine the clinical safety and effectiveness of exosome therapy for hair growth, particularly androgenetic alopecia (AGA) and other forms of hair loss. Systematic searches were conducted on PubMed, Scopus, and Embase databases to find clinical studies published from inception until 10th May 2025 that explored exosome-based interventions for hair loss. Eleven studies included: two RCTs, three retrospective studies, three prospective single-arm studies, one case series, and two case reports. Extracted data included method of preparation, outcomes of hair regrowth (density, thickness, patient satisfaction), and side effects. Quality of evidence was assessed using the Oxford Centre for Evidence-Based Medicine (OCEBM) levels and risk of bias tools (RoB 2 and ROBINS-I). All the studies included demonstrated improvements in at least one hair parameter, with MSC-derived exosomes from adipose tissue, placenta, hair follicles, bone marrow, foreskin, and umbilical cord having substantial increases in hair density (9.5 to 35 hairs/cm²) and hair thickness (up to 13.01 µm). Patient satisfaction was generally high (3-10 point scales), and no serious adverse events were noted. The greatest level of evidence came from RCTs with adipose- and plant extract-derived exosome formulation. However, heterogeneity in design and outcome limited direct comparisons. Exosome therapy, particularly with MSC-derived sources, appears to be a new and safe treatment modality for hair restoration in AGA and other alopecias. The current evidence is, however, limited by heterogeneity in studies, small sample sizes, and varying follow-up durations. More well-standardized, high-quality RCTs are required to confirm these findings and establish standardized treatment protocols.