Protective effect of mesenchymal stem cells on renal tubular epithelial cells in mice under ischemia/reperfusion

Abstract

Objective To observe the effects of mesenchymal stem cells (MSCs) on self-repair of renal tubular epithelial cells ( RTECs) in mice under ischemia/reperfusion ( IR). Methods MSCs in C57BL/6 mice were successfully isolated by Percoll density gradient centrifugation and adherence cultivation, then marked with BrdU. Forty-five healthy male C57BL/6 mice were assigned to control group (n =15 ) , I/R group (n = 15 , clamping bilateral renal pedicles and then reopening after 30 min) , I/R + BrdU-MSCs group (n = 15 , clamping bilateral renal pedicles and then reopening after 30 min, meanwhile, BrdU-marked MSCs were injected through caudal vein into the body of model mice). One, 2,3,7 and 14 days later, the mice were killed (n = 3/each group) , and blood and kidneys were obtained. Serum creatinine (Scr) and urea nitrogen (BUN) were determined, and mice kidneys were stained with Hematoxylin and Eosin ( HE) to observe their pathological changes. The distribution of MSCs in mice was observed by using fluorescence histochemistry. The expression of proliferating cell nuclear antigen ( PCNA) in RTECs was assessed by using immunohistological staining. The apoptosis of RTECs was detected by using TUNEL. The protein levels of Caspase-3 and bcl-2 in renal tubules on the day 2 after establishing the model were detected by using Western blotting. Results The positive BrdU marking ratio was (98. 71 ±0. 32) % in MSCs.As compared with I/R group, the levels of BUN and Scr in I/R + BrdU-MSCs group were significantly reduced, and pathological changes in renal tubules were alleviated significantly. BrdU-marked MSCs desposited in the kidneys of I/R + BrdU-MSCs group. The positive PCNA expression of RTECs was increased significantly after intervention of BrdU-MSCs (P ＜0. 05 or P ＜0. 01) , while the apoptosis relieved significantly. Western blotting analysis revealed: as compared with I/R group, the level of Caspase-3 in I/R + BrdU-MSCs group was decreased notably [(1.16±0.33) vs (1.64±0.27), P＜0.01], while the level of bcl-2 increased significantly [(0.94±0.27) vs (0.68±0.15), P＜0.01). Conclusion Acute renal injury by I/R can induce MSCs homing to injured kidney and anchoring here. The anchored MSCs can contribute to RTECs' self-repair of mice under ischemia/reperfusion, inhibit their apoptosis, which is helpful to the RTECs' self-repair and can delay the progression of renal injury. Key words: Mesenchymal stem cells; Ischemia/reperfusion; Renal tubular; Epithelial cells