Human umbilical cord mesenchymal stem cell-derived exosomes enhance follicular regeneration in androgenetic alopecia via activation of Wnt/β-catenin pathway.

BACKGROUND: Exosomes isolated from human umbilical cord mesenchymal stem cells (hUCMSCs) have demonstrated the capacity to alleviate dihydrotestosterone (DHT)-induced disruptions in the hair follicle growth cycle. However, the precise role and underlying mechanisms by which hUCMSC-derived exosomes influence hair shaft regeneration in androgenetic alopecia (AGA) remains unclear. METHODS: hUCMSCs were isolated using fluorescence-activated cell sorting following enzymatic digestion with TrypLE™ Express. Exosomes derived from these hUCMSCs were purified through ultracentrifugation and subsequently characterized by transmission electron microscopy and Western blotting to confirm their morphology and protein markers. To model human AGA, mice received daily subcutaneous injections of dihydrotestosterone. The effects of MSC-derived exosomes (MSC-Exo) on hair follicle growth were evaluated through transparent skin visualization, hematoxylin and eosin staining, and immunofluorescence assays. Additionally, EnoGeneCell™ Counting Kit-8 assays and scratch wound healing assays were conducted to assess the proliferative and migratory responses of human dermal papilla cells (hDPCs) following MSC-Exo treatment. RESULTS: In vivo, MSC-Exo significantly promoted hair follicle enlargement and facilitated the transition of follicles into the anagen (growth) phase. These exosomes modulated the proliferation and differentiation of key cellular players in hair follicle biology, particularly dermal papilla cells, while also altering the secretory profile of hDPCs. Notably, high levels of two microRNAs, miR-21-5p and let-7b-5p, were identified within hUCMSC exosomes. Both microRNAs are recognized regulators of genes critical to hair follicle function, including Cyclin D1, c-MET, and LEF1, which collectively activate the Wnt/β-catenin signaling pathway and thereby enhance the functional differentiation of hDPCs. CONCLUSIONS: Exosomes derived from hUCMSCs enrich miR-21-5p and let-7b-5p, which target key genes such as Cyclin D1, c-MET, and LEF1 to activate the Wnt/β-catenin pathway, promoting hair shaft regrowth in an AGA model. These findings reveal a novel therapeutic target for stem cell-derived exosomes and underscore their potential in activating Wnt/β-catenin signaling for the treatment of AGA. Our study provides new insights into the mechanistic role of stem cell exosomes in AGA and advances the development of regenerative therapies for this condition.