Objective To study the possible mechanism of stromal derived factor-1 (SDF-1) on proliferation and migration of endothelial progenitor cells (EPCs) in patients with hypertensive intracerebral hemorrhage,so as to explore the SDF-1/CXC chemokine receptor-4 (CXCR4) axis as a target participate in vascular repairment.Methods The endothelial progenitor cells were isolated from 15 ml peripheral venous blood in male patients with acute cerebral hemorrhage.Six days later,the culture EPCs were stimulated with various concentrations of SDF-1 for 24 h.Then,3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used to assess the proliferation of EPCs,and cell migration was analyzed by transwell chamber assay.Furthermore,the expression levels of CXCR4 and α5β1 protein were detected by Western blotting after pretreatment with the chemically synthesized CXCR4-siRNA or anti-α5 β1 antibody.Results SDF-1 dose-dependently increased the proliferation and migration of EPCs in patients with hypertensive cerebral hemorrhage (A:0.57 ± 0.03,P ＜ 0.05) ; further mechanism analysis showed that SDF-1 induced the expression of CXCR4 protein with an about two fold increase (P ＜ 0.05),which was accounted for SDF-1-induced cell proliferation and migration as pretreatment with CXCR4 siRNA significantly abolished EPCs proliferation and migration induced by SDF-1 (A:0.363 ± 0.020).Furthermore,SDF-1 enhanced the expression of α5β1 protein with an about two fold increase by CXCR4 pathway,because preconditioning with CXCR4 siRNA obviously attenuated SDF-1-induced upregulation of α5β1 expression.Further analysis confirmed that pretreatment with α5β1 antibody dramatically inhibited α5β1 expression,concomitant with a significant decrease in EPCs proliferation and migration induced by SDF-1/ CXCR4 (A:0.311 ±0.037,migration cells:25.52 ±5.60).Conclusion SDF-1 dose-dependently increased EPCs proliferation and migration in patients with acute cerebral hemorrhage through CXCR4-mediated α5β1 pathway.Consequently,our findings will clarify a new explanation about how SDF-1 induced EPCs proliferation and migration,and provide a potential target for vascular repair after damage.