Regenerative potential of extracellular vesicles from endometrial mesenchymal stem cells for modulating fibrosis and wound healing

BACKGROUND: Fibrotic scarring resulting from trauma, burns, or surgery affects over 100 million people annually and is associated with functional, aesthetic, and psychological burdens. Current treatments remain inadequate, highlighting the need for novel, effective, and cell-free therapeutic strategies. Extracellular vesicle-enriched preparations derived from human endometrial mesenchymal stem cells (eMSC-EV-enriched preparations) may possess regenerative and anti-fibrotic potential, yet their roles in scar modulation and underlying mechanisms remain unclear. METHODS: eMSCs were isolated from human endometrial biopsies and characterized via flow cytometry and differentiation assays. The eMSC-EV-enriched preparations were obtained from conditioned medium and verified by TEM, NTA, and Western blotting. Functional assays were conducted in NIH3T3 fibroblasts to assess proliferation, migration, and transwell invasion capacity. A full-thickness cutaneous wound model and a bleomycin-induced dermal fibrosis model were used in C57BL/6 mice to evaluate tissue repair and fibrosis attenuation. Histological and molecular analyses were performed to assess collagen deposition, fibrosis-associated markers, and related signaling pathways. The potential involvement of miR-125b-5p in Smad2-related signaling was explored. RESULTS: The eMSC-EV-enriched preparations displayed characteristic vesicular morphology and marker expression. Compared with BMMSC-EV-enriched preparations, eMSC-EV-enriched preparations more effectively reduced fibroblast proliferation and migration, with decreased transwell invasion capacity in vitro. In vivo, the eMSC-EV-enriched preparations enhanced wound closure, reduced collagen deposition, and were associated with improved collagen organization and an increased number of appendage-like structures. Expression of α-SMA and collagen I and III was reduced in tissues treated with the eMSC-EV-enriched preparations. Furthermore, the preparations were associated with increased miR-125b-5p levels and decreased Smad2/p-Smad2 expression, suggesting involvement of the miR-125b-5p/Smad2 axis. In the bleomycin model, the eMSC-EV-enriched preparations attenuated dermal thickening and collagen accumulation during fibrosis induction. CONCLUSIONS: Our findings indicate that eMSC-EV-enriched preparations improve repair quality and attenuate fibrosis development, potentially through modulation of fibroblast activity and involvement of the miR-125b-5p/Smad2 signaling pathway. These findings support further investigation of eMSC-EV-enriched preparations as a cell-free strategy for improving tissue remodeling in fibrotic skin conditions.