Extracellular vesicles of human transformed skin-derived precursors containing miR-221-3p promote hair growth through DKK2-mediated Wnt/β-catenin signaling.

Stem cells and their paracrine factors hold promise for alopecia treatment, yet research on human skin-derived precursors (hSKPs), which are closely related to hair follicles in biological positioning and function, remains limited. We demonstrated that extracellular vesicles of human transformed skin-derived precursors (htSKP-EVs), harvested utilizing our directed induction, culture transition and gradient ultracentrifugation technology, exhibited superior efficiency and quality determined by transmission electron microscopy, nanoparticle tracking analysis, and detection of specific markers. Using CCK8, scratch assay, immunofluorescence, H&E staining, immunohistochemistry staining, dermoscope, qRT-PCR and Western blotting, it was found that htSKP-EVs significantly promoted the proliferation of hair follicle stem cells (hHFSCs) by effectively modulating the Wnt signaling pathway, thereby enhancing overall hair follicle growth. Notably, miR-221-3p, highly expressed in htSKP-EVs, suppressed DKK2 expression, activated the Wnt pathway in human dermal papilla cells (hDPCs), and induced hair follicles to enter and sustain the anagen phase, based on the aforementioned similar in vivo and in vitro experiments. These findings, validated in hHFSCs, hDPCs and human hair follicles in vitro and in a murine alopecia model in vivo, revealed the potential mechanism of htSKP-EVs in hair growth and identified a new therapeutic target for alopecia in regenerative medicine.