Protective effect of melatonin‐supported adipose‐derived mesenchymal stem cells against small bowel ischemia‐reperfusion injury in rat

We tested the hypothesis that combined melatonin and autologous adipose‐derived mesenchymal stem cells ( ADMSC ) was superior to either alone against small bowel ischemia‐reperfusion ( SBIR ) injury induced by superior mesenteric artery clamping for 30 min followed by reperfusion for 72 hr. Male adult Sprague Dawley rats (n = 50) were equally categorized into sham‐operated controls SC , SBIR , SBIR ‐ ADMSC (1.0 × 10 6 intravenous and 1.0 × 10 6 intrajejunal injection), SBIR ‐melatonin (intraperitoneal 20 mg/kg at 30 min after SI ischemia and 50 mg/kg at 6 and 18 hr after SI reperfusion), and SBIR ‐ ADMSC ‐melatonin groups. The results demonstrated that the circulating levels of TNF ‐ α , MPO , LyG6+ cells, CD 68+ cells, WBC count, and gut permeability were highest in SBIR and lowest in SC , significantly higher in SBIR ‐ ADMSC group and further increased in SBIR ‐melatonin group than in the combined therapy group (all P  < 0.001). The ischemic mucosal damage score, the protein expressions of inflammation ( TNF ‐ α , NF ‐ κ B, MMP ‐9, MPO , and iNOS ), oxidative stress ( NOX ‐1, NOX ‐2, and oxidized protein), apoptosis ( APAF ‐1, mitochondrial Bax, cleaved caspase‐3 and PARP ), mitochondrial damage (cytosolic cytochrome C) and DNA damage ( γ ‐H2 AX ) markers, as well as cellular expressions of proliferation ( PCNA ), apoptosis (caspase‐3, TUNEL assay), and DNA damage ( γ ‐H2 AX ) showed an identical pattern, whereas mitochondrial cytochrome C exhibited an opposite pattern compared to that of inflammation among all groups (all P  < 0.001). Besides, antioxidant expressions at protein ( NQO ‐1, GR , and GP x) and cellular ( HO ‐1) levels progressively increased from SC to the combined treatment group (all P  < 0.001). In conclusion, combined melatonin‐ ADMSC treatment offered additive beneficial effect against SBIR injury.