Effect of CXCR4-overexpressing bone marrow-derived mesenchymal stem cells on the repair of the co-cultured hypoxia/re-oxygenation renal tubular epithelial cells and its possible mechanism

Objective CXCR4-overexpressing bone marrow-derived mesenchymal stem cells (CXCR4-BMSC) were constructed and co-cultured with hypoxia/re-oxygenation pretreated renal tubular epithelial cells (HR-RTEC). Repair of HR-RTEC was detected and the possible mechanism was also discussed. Methods CXCR4-BMSC (CXCR4-BMSC/eGFP, eGFP as the tracer gene) and null-BMSC (BMSC/eGFP) were obtained by gene transfection technique, and the level of CXCR4 in the transfected cells was detected. RTEC was cultured under hypoxia/re-oxygenation condition for 12 h, respectively, to obtain HR-RTEC, which was used to simulate AKI in vitro. BMSC and HR-RTEC were co-cultured for 12 h, and the proportion of apoptotic cells among the HR-RTEC was assayed by immunofluorescence technique. Western blot was used to test the protein levels of cleaved Caspase-3 and Bcl-2. The number of migrating BMSC was also assayed. After culturing with the HR-RTEC culture supernatant, the expression of cytokeratin 18 (CK18) in BMSC was tested by immunofluorescence staining. Cytokines including bone morphogenetic protein-7 (BMP-7), hepatic growth factor (HGF) and interleukin-10 (IL-10) in the BMSC culture supernatant were detected by ELISA method. Results Expression of CXCR4 was enhanced in CXCR4-BMSC. Proportions of the apoptotic cells among HR-RTEC after being co-cultured with BMSC, CXCR4-BMSC and null-BMSC were all decreased, especially in the C/H group. The decreased cleaved Caspase-3 and enhanced Bcl-2 were also observed in HR-RTEC. The number of migrating CXCR4-BMSC was the highest. Proportions of CK18+ cells in BMSC, CXCR4-BMSC and null-BMSC were all low and showed no difference. However, CXCR4 overexpression in BMSC stimulated secretions of BMP-7, HGF and IL-10. Conclusions CXCR4-overexpressing BMSC has more repair effect on the co-cultured HR-RTEC, the enhanced migration ability and secretion ability of CXCR4-BMSC are the possible mechanisms.