Protective Effect Of MSCs By Distinct Administration Time On Renal Ischemia-Reperfusion Injury In Rats

Objective To observe the protection and distribution of bone marrow mesenchymal stem cells (MSCs) by distinct intravenous infusion time on renal ischemia-reperfusion injury (IRI) in rats.Methods (1) Rat bone marrow mesenchymal stem cells (MSCs) were separated by adherent cell separation and induced to differentiate into fat cells and osteoblasts cells. The cell surface markers were detected by flow cytometry.(2) Two transfection methods of DAPI(4’,6-diamidino-2-phenylindole) and GFP(enhanced green fluorescent protein) were used to label MSCs and the transfection effects of both methods were observed. The labeled MSCs were administrated at distinct times to the rats for MSCs chemotaxis observation.(3) We used unilateral nephrectomy and contralateral vascular occlusion method to establish renal ischemia-reperfusion injury model in rats.80male SD rats were randomized into five groups. The control groups included sham operation group and ischemia group. MSCs groups which received2x10" MSCs infusion through tail vein, were subsequently divided into3groups:2-h pre-reperfusion (PreOp), immediately after reperfusion (Op),6-h post-reperfusion (PostOp).(4)8rats of each group were sacrificed to observe the chemotaxis of DAPI and GFP labeled MSCs6-h after administration in the IR kidney.(5) Renal function was detected at6-h,24-h,48-h respectively after operation (n=8).48-h after operation, kidney tissues were harvested to observe the pathological changes by HE staining and the tubular epithelial cell apoptosis via TUNEL assay (n=8)Results (l) MSCs had high purity and good activity in the3-6generation separated by adherent cell separation method, and high expression of CD29, CD44and low expression of CD34analyzing by flow cytometry of the cell surface markers. MSCs can be induced to differentiate into fat cells and osteoblasts cells by fat and osteoblasts induced fluid.(2) MSCs can be labeled by both DAPI and GFP methods, of which DAPI method is more appropriate to mark MSCs, it has the features of long fluorescence time, non-toxicity and inexpensive advantages.(3) Chemotaxis of MSCs can be found in the experimental groups after IR in the kidney, but post-reperfusion administration of MSCs compared with pre-reperfusion and immediately reperfusion, the chemotaxis efficiency was significantly increased, renal pathological changes and number of apoptotic cells were better (P<0.05).(4) Compared with IR group, the experimental groups have better renal function, lighter pathological changes, damage reduction, decreased renal tubular cell apoptosis, difference was statistically significant (P<0.05). Renal function among all experimental groups has no significant difference (P>0.05).Conclusions (1) MSCs have protective effects on rat renal ischemia-reperfusion injury.(2) Post-reperfusion administration of MSCs leads to the best chemotaxis efficiency and protection.