Abstract: 【Abstract】Objective To investigate the overexpression of Klotho gene on the expression of renal vascular endothelial growth factor (VEGF) in order to explore the protective role of Klotho on acute kidney injury (AKI) in mice. Methods Mouse bone marrow mesenchymal stem cells (BMSCs) were infected with the recombinant lentivirus to efficiently and stably express Klotho (BMSCs-Klotho), and those infected with the parent lentivirus was used as the control (BMSCs-EV). AKI model was established by intramuscular injection of 50% glycerol to the interior side of both legs to induce rhabdomyolysis in mice. Thirty male C57BL/6 mice were randomly and equally divided into 5 groups: normal control group (Ctrl group), AKI with PBS intervention (AKI+PBS group), AKI with BMSCs-Klotho intervention (AKI+BMSCs-Klotho group), AKI with BMSCs- EV intervention (AKI+BMSCs-EV group), and AKI with BMSCs intervention (AKI+BMSCs group). Mice were treated with the intervention after AKI for 6 hours, and were sacrificed after the intervention for 3 days. Serum creatinine (Scr) and blood urea nitrogen (BUN) were measured by routine biochemical methods, and the expression of VEGF in kidney was assayed by immunohistochemistry and immunoblot. Results Scr and BUN levels increased in AKI+PBS group, AKI+BMSCs-Klotho group, AKI+BMSCs-EV group and AKI+ BMSCs group as compared to those in Ctrl group (for Scr, F=370.705, P＜0.001, P＜0.001, P＜0.001 and P＜0.001, respectively; for BUN, F=307.656, P＜0.001, P＜0.001, P＜0.001 and P＜0.001, respectively). Scr and BUN levels were lower in AKI+BMSCs-Klotho group than in AKI+PBS group, AKI+BMSCs-EV group and AKI+BMSCs group (for Scr, P＜0.001, P＜0.001 and P＜0.001, respectively; for BUN, P＜0.001, P＜0.001 and P＜0.001, respectively). The expression of VEGF in kidney as assayed by immunoblot and immunohistochemistry was significantly lower in AKI+PBS group than in Ctrl groups (P＜0.001). The expression of VEGF in kidney was significantly higher in AKI+BMSCs-Klotho group than in AKI+PBS group, AKI+BMSCs-EV group and AKI+BMSCs group (for immunoblot, P＜0.001, P＜0.001 and P＜0.001, respectively; for immunohistochemistry, P＜0.001, P＜0.001 and P＜0.001, respectively), but had no statistical significance between AKI+BMSCs-Klotho group and Ctrl group (for immunoblot, P=0.884; for immunohistochemistry, P= 0.809). Conclusion Klotho has a protective effect on AKI through up-regulation of VEGF in kidney in mice.

Key words: Klotho gene, Bone marrow mesenchymal stem cells, Acute kidney injury, Vascular endothelial growth factor