Exosomes Derived From Umbilical Cord Mesenchymal Stem Cells Promote Healing of Complex Perianal Fistulas in Rats

The study examined the effects of exosomes derived from human umbilical cord mesenchymal stem cells (hUC-MSCs-Exo) on healing complex perianal fistulas in 40 male Sprague–Dawley rats. The results showed that hUC-MSCs-Exo significantly promoted healing by reducing fistula diameter, enhancing epithelialization, and shortening the fistula tract, likely through the HIF-1α/TGF-β1/Smad pathway. This treatment improved histopathological outcomes, reduced inflammation, increased collagen content, enhanced angiogenesis, and modulated inflammatory cytokine levels and gut microbiota diversity. The optimal therapeutic effect was observed at a dosage of 10 µg/100 µL. The findings suggest that hUC-MSCs-Exo could be a promising, non-invasive treatment for complex perianal fistulas, with significant improvements in tissue repair and immune response modulation.