Mesenchymal Stem Cells,Not Conditioned Medium,Contribute To Kidney Repair After Ischemia-reperfusion Injury

Aims: Studies have shown that stem cells have the therapeutic effects on acute kidney injury(AKI)through paracrine/endocrine actions.Methods: To investigate the beneficial effects of mesenchymal stem cells(MSCs)and conditioned medium(CM)on kidney repair after ischemia-reperfusion(I/R)injury,we cultured MSCs and then transplanted them into an I/R model.CM was also injected into mice,and the histological changes,level of cell proliferation and loss of peritubular capillaries(PTCs)were examined at different time points.Results: The results showed that MSC infusion improved renal function and histological alterations,leading to significantly reduced mortality.MSC infusion also promoted kidney microvasculature repair,attenuated kidney PTC loss,increased the proliferation of parenchymal cells and decreased CD68-positive macrophage infiltration and apoptotic cells.Although we determined that CM contained proangiogenic factors,including hepatocyte growth factor(HGF),vascular endothelial growth factor-A(VEGF-A)and insulin-like growth factor-1(IGF-1),no favorable effects were observed during the course of repair.Conclusions: In conclusion,our data show that MSC infusion promoted kidney repair by enhancing the repair of PTCs and tubular epithelial cells.MSCs can secrete high levels of proangiogenic growth factors,but CM resulted in a nonsignificant improvement,indicating that MSCs play roles in kidney repair through paracrine rather than endocrine mechanisms.