Mesenchymal stem cell-derived exosomes promote scalp rejuvenation through type XVII collagen regulation via the miR-21-5p/DKK2/Wnt pathway.

Summary

hUC-MSC exosomes reduced senescence markers, restored COL17A1, and enhanced hair regeneration in mice, surpassing minoxidil. Mechanistically, abundant exosomal miR-21-5p directly targets DKK2, relieving Wnt inhibition, activating β-catenin signaling, and upregulating COL17A1; inhibition of miR-21-5p blunted these effects.

Key Findings

• Exosome treatment reduced SA-β-gal-positive cells from 67.5% to 21.4% and increased COL17A1 mRNA 2.67-fold with near-restored protein levels.
• Hair follicle elongation increased by 47.4%, and mice achieved 92.4% hair coverage versus 45.6% controls, outperforming minoxidil (78.3%).
• miR-21-5p was the most abundant exosomal miRNA, directly targeting DKK2 to activate Wnt/β-catenin and upregulate COL17A1; miR-21-5p inhibition partially abrogated effects.

Clinical Implications

Suggests a tractable exosome-based therapeutic avenue for androgenetic alopecia or age-related hair thinning, pending human safety, dosing, delivery optimization, and GMP manufacturing.

Limitations

• Preclinical models; absence of human clinical data
• Exosome heterogeneity and translational challenges in large-scale, standardized manufacturing and delivery

Future Directions

Phase 1 trials assessing safety/tolerability, dose-ranging and delivery routes, biodistribution, and comparative efficacy versus standard agents; development of GMP-grade, characterized exosome products.