Epidermal stem cell derived exosomes-induced dedifferentiation of myofibroblasts inhibits scarring via the miR-203a-3p/PIK3CA axis.

Hypertrophic scar (HS) is a common fibroproliferative disorders with no fully effective treatments. The conversion of fibroblasts to myofibroblasts is known to play a critical role in HS formation, making it essential to identify molecules that promote myofibroblast dedifferentiation and to elucidate their underlying mechanisms. In this study, we used comparative transcriptomics and single-cell sequencing to identify key molecules and pathways that mediate fibrosis and myofibroblast transdifferentiation. Epidermal stem cell-derived extracellular vesicles (EpiSC-EVs) were isolated via ultracentrifugation and filtration, followed by miRNA sequencing to identify miRNAs targeting key molecules. After in vitro and in vivo treatment with EpiSC-EVs, we assessed antifibrotic effects through scratch assays, collagen contraction assays, Western blotting, and immunofluorescence. Transcriptomic sequencing and rescue experiments were used to investigate the molecular mechanism by which miR-203a-3p in EpiSC-EVs induces myofibroblast dedifferentiation. Our results indicate that PIK3CA is overexpressed in HS tissues and positively correlates with fibrosis. EpiSC-EVs were absorbed by scar-derived fibroblasts, promoting dedifferentiation from myofibroblasts to quiescent fibroblasts. Mechanistically, miR-203a-3p in EpiSC-EVs plays an essential role in inhibiting PIK3CA expression and PI3K/AKT/mTOR pathway hyperactivation, thereby reducing scar formation. In vivo studies confirmed that EpiSC-EVs attenuate excessive scarring through the miR-203a-3p/PIK3CA axis, suggesting EpiSC-EVs as a promising therapeutic approach for HS.