Objective:To investigate the role of endothelial progenitor cells(EPCs) in modulation of ischemic injury in a nephron sparing surgery (NSS) rat model by ischemic preconditioning (IPC). Methods:Sprague-Dawley rats were randomly divided into three groups after right-side kidney nephrectomy:the Sham group underwent surgery without vascular clamping;the NSS group,the renal blood vessels were clamped for 40 min and partial nephrectomy(PN) was performed;the IPC group,the rats were pretreated with 15 min ischemia and 10 min reperfusion. At 24 h after reperfusion,the pool of circulating and kidneys were harvested. We assessed the extent of renal injury,observed the home of EPCs and detected angiogenesis as well as the expression of vascular growth factor. Results:Pretreated rats exhibited significant improvements in renal function and morphology. The number of EPCs in the kidneys was increased in the IPC groups as compared to the NSS or sham groups. Neovascularization in peritubular capillaries was markedly increased in the kidneys which treated with IPC. In addition,the expression of SDF-1 mRNA in kidneys of pretreated rats was increased compared to rats subjected to ischemic injury. Conclusion:IPC may attenuate renal ischemic injury induced by NSS;EPCs play an important role in renal protection,which involves the promotion of angiogenesis through the release of several angiogenic factors.