ObjectiveTo observe the effect of osteopontin (OPN) on the proliferation of endothelial progenitor cells (EPCs) and to explore the underlying mechanisms.MethodsThe total mononuclear cells (MNCs) were isolated from bone marrow by Ficoll density gradient centrifugation, and EPCs were obtained by differential attachment technique from MNCs after culture for 8 days.The EPCs were identified by morphology observation, flow cytometry and test of the ability to intake the acLDL and bind UEA-1.OPN expression in EPCs was examined by immunohistochemistry and RT-PCR.EPC proliferation was assayed by CCK-8 assay after EPCs were treated with different concentrations of OPN or the inhibitors of phosphoinositide 3-kinase (PI3K) and Akt (LY294002 and Akt inhibitor).ResultsThe recombinant OPN protein increased EPC proliferation in a dose-dependent manner, and inhibition of the PI3K/Akt pathway blocked the influence of OPN on the proliferation of EPCs.ConclusionRecombinant OPN plays an important role in regulating the in vitro proliferation of bone marrow-derived EPCs via PI3K/Akt pathway.