• The study validates hUCMSC-derived exosomes as a promising minimally invasive therapy for complex perianal fistulas, acting via HIF-1α/TGF-β/Smad pathway and microbiota modulation.
• Rodent models have anatomical and microbiota disparities that limit clinical translation; large-animal models (porcine, canine) are recommended for validation.
• Long-term safety of exosome therapy, including potential off-target effects and immune priming, requires systematic evaluation before clinical adoption.
• Refined preclinical models should incorporate extended fistula retention, repeated microbial stimulation, and advanced imaging (contrast-enhanced MRI) to better mimic chronic human disease.