Effects of mesenchymal stem cells surface CXC chemokine receptor 4 over-expression on repair of ischemia reperfusion injured kidney

Abstract

Objective To observe the effects of mesenchymal stem cells (MSCs) surface CXC chemokine receptor 4 over-expression on the repair of kidney after ischemia reperfusion (I/R) injury. Methods The MSCs were co-cultured with I/R injured renal cell homogenate supernatant. The MSCs surface CXCR4 and stromal cells derived factor-1 (SDF-1α) protein levels were detected by Western blot, chemotactic ability of MSCs to SDF-1 was investigated by transwell test. The I/R injured renal model was made and pathological changes were observed in control group, I/R group, MSCs injection group and CXCR4 neutralize antibody group. Renal CXCR4 protein expression was measured by immunofluorescence histochemistry, SDF-1α、CXCR4、hepatocyte growth factor (HGF) and epidermal growth factor (EGF) mRNA were detected by Real-time quantitative polymerase chain reaction (RT-PCR). Comparisons among multiple groups were performed using One-way analysis of variance, and comparisons between groups were carried out using independent-sample t-test. Results In vitro, the SDF-1α protein expression markedly increased in I/R injured renal tissue homogenate, but the difference was not significant between I/R group and CXCR4 antibody group (t=0.862, P=0.403). MSCs surface CXCR4 protein expression increased significantly after co-cultured with I/R injured renal tissue homogenate (F=95.957, t=10.166, P <0.01) , and the chemotactic ability of MSCs to SDF-1 increased at the same time (F=82.459, t=6.826, P <0.01) , the CXCR4 protein expression (t=13.657, P <0.01) and the chemotactic ability (t=12.662, P <0.01) could be decreased by CXCR4 neutralize antibody. In vivo, renal tubular structure was destroyed in I/R group. After MSCs injection, the renal pathological injury improved rapidly, but the improvement could be inhibited by CXCR4 antibody. The expression of SDF-1α mRNA and level of SDF-1a protein increased in I/R group, but there was no significant difference among different groups (F=1.909, P=0.173). MSCs injection markedly up-regulated the CXCR4 protein and mRNA expression (F=6.663, P=0.006). Following the increase in CXCR4 expression, the expressions of HGF mRNA (F=11.898, P <0.01) and EGF mRNA (F=5.309, P <0.05) increased gradually which could be restrained by CXCR4 antibody (t=5.312, t=4.310, P <0.01). Conclusions I/R injured renal microenvironment markedly increased the mesenchymal stem cells surface CXCR4 expression, and increased CXCR4 expression can induce MSCs chemotaxis and stimulate the secretion of renal protective growth factors paracrine promoting the repair of the kidney. Key words: Mesenchymal stem cells; CXC chemokine receptor 4; Ischemia reperfusion injury; Rats; Renal injury; Chemotaxis; Paracrine; Recovery