Background: Gastrocutaneous fistulae following sleeve gastrectomy represent a serious complication associated with prolonged and complex management. To explore innovative therapeutic options, we aimed to develop representative and reproducible animal models to evaluate the potential of extracellular vesicles (EVs) derived from adipose-derived stromal cells (ADSCs). Design: Chronic gastrocutaneous fistulae were surgically induced following sleeve gastrectomy in both Wistar rats and Large-White pigs. In the rat model, animals received local administration of either saline (control, n=8), thermoresponsive hydrogel alone (gel, n=8), ADSC-derived EVs (n=8), EVs combined with hydrogel (EVG, n=8), or ADSCs themselves (n=7). In the porcine model, the effect of EVG (n=8) was compared to gel (n=8) and control (n=8). The primary endpoint was complete healing of the external orifice, marked by cessation of fistula output. Fistula healing was also assessed using radiological and histological criteria. Results: Chronic gastrocutaneous fistula models were successfully developed in both species. In rats, external healing occurred in 1/8 (control), 2/8 (gel), 7/8 (EV), 5/8 (EVG), and 4/7 (ADSC) animals. Healing rates were significantly higher in the EV group compared to control (p=0.01) and gel (p=0.041). Similarly, in pigs, EVG treatment showed significantly improved healing compared to control (p=0.01) and gel (p=0.041). Secondary assessments supported enhanced fistula tract closure in the EV and EVG groups. Conclusion: We describe the first validated animal models of chronic gastrocutaneous fistulae following sleeve gastrectomy and provide a proof-of-concept for the therapeutic benefit of ADSC-derived EVs, especially when combined with a thermoresponsive hydrogel. · Extracellular vesicles improve closure of gastrocutaneous fistulae. · Efficacy demonstrated in rat and pig sleeve gastrectomy models. · Novel preclinical models of gastrocutaneous fistula are described. · Adipose stromal cell EVs show potential for fistula treatment.