Incorporation and recruitment of endothelial progenitor cells from human umbilical cord blood in glioma neovascularization

Objective To investigate the effects of endothelial progenitor cells(EPCs) derived from human umbilical cord blood on glioma neovascularization in vivo.Methods EPCs were isolated from human umbilical cord blood by density gradient centrifugation.U87 glioblastoma cells were implanted into the brain of nude mice using a stereotactic technique for replicating an orthotopically implanted human glioblastoma model.On day 7 after U87 cell implantation,EPCs were injected into tumor-bearing mice via their vena caudalis.Incorporation and recruitment of endothelial progenitor cells in neovascularization of malignant glioma in vivo were examined respectively by confocal laser scanning microscopy on day 7,14,21 after EPCs transplantation,and the expansion of the tumor mass were observed.Results Gliomas were formed in all the injected nude mice.The number of EPCs incorporated and recruited into newly formed tumor vessels on day 14,21 after EPCs transplantation were significantly exceeded that at day 7(P0.05).Moreover,the volume and vascular density of U87 xenotransplant were significantly increased in EPCs group than those in control group(P0.05).Conclusion EPCs derived from human umbilical cord blood may be recruited and incorporated into the growing brain tumor neovasculature,and promote tumor growth,which suggests that EPCs may play an important role in glioma neovascularization.