Hypoxia-pretreated exosomes promote enterocutaneous fistula healing via regulating inflammation and tissue repair.

BACKGROUND

Enterocutaneous fistula (ECF) is an abnormal pathological passage. This study aims to investigate the role and mechanism of action of gelatin sponges loaded with hypoxic exosomes (GS-Hypo-Exos) in the treatment of enterocutaneous fistulas.

METHODS

A rat ECF model was established and subjected to intervention therapy, with the following groups: control group, gelatin sponge loaded with PBS group (GS-PBS), gelatin sponge loaded with hypoxia-exosomes group (GS-Hypo-Exos), and gelatin sponge loaded with normoxic exosomes group (GS-Nor-Exos). After 21 days of intervention, rat serum and perifistulous tissue were collected. Inflammatory response and collagen were analyzed via ELISA and histological staining. Flow cytometry determined macrophage phenotype proportions in fistula tissue. Immunofluorescence staining assessed angiogenesis. In vitro experiments further examined the effects of GS-Hypo-Exos on epithelial cell, fibroblast, endothelial cell, and macrophage function.

RESULTS

The GS-Hypo-Exos group demonstrated the most significant fistula healing effect. This group exhibited the lowest serum IL-1β levels and the highest IL-10 levels. Histopathological analysis revealed reduced inflammatory cell infiltration and increased collagen deposition in fistula tissues following GS-Hypo-Exos treatment. Flow cytometry analysis revealed a significant increase in the proportion of M2 macrophages within the GS-Hypo-Exos group. Enhanced signaling of angiogenesis-related markers indicated increased mature vascular structures. In vitro experiments confirmed that GS-Hypo-Exos promoted HaCaT cell proliferation and migration, enhanced fibroblast collagen synthesis capacity, improved endothelial cell tube formation ability, and drove macrophage polarization toward the M2 phenotype.

CONCLUSIONS

The GS-Hypo-Exos suppress inflammatory responses, enhance the function of key repair cells, promote collagen deposition and neovascularization, thereby creating conditions for fistula tissue repair.

CLINICAL TRIAL NUMBER: Not applicable.