Adipose-derived extracellular vesicles miR-423-5p targets SMAD3 to reverse endometrial fibrosis in a porcine model of intrauterine adhesion: insights from single-cell sequencing.

Intrauterine adhesion (IUA), a fibrotic cause of female infertility, lacks effective therapies due to high recurrence following surgical intervention. Extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) show promise in small-animal models, yet clinical translation is hindered by poor retention and the absence of large-animal validation. To address this, we developed a thermosensitive chitosan hydrogel (GelCT) as an EV carrier for autologous adipose MSC-EV delivery in a porcine IUA model. EVs-GelCT significantly attenuated fibrosis, restored endometrial architecture, and enhanced vascularization. Single-cell transcriptomics revealed that EVs remodel fibroblast subpopulations, specifically suppressing pro-fibrotic F2 (ECM-reparative) and F3 (inflammation-associated) clusters. Integrated miRNA profiling identified miR-423-5p as a functional EV cargo that directly targets SMAD3 3'UTR, thereby inhibiting TGF-β/Smad signaling. This first-in-porcine demonstration establishes the miR-423-5p/SMAD3 axis as a therapeutically actionable mechanism for IUA, advancing EV-based strategies from proof of concept to clinical translation.