Abstract: Objective: To explore the effect of VEGF-induced up-regulation of CCN2 in osteoblasts mediates biological behavior in human umbilical endothelial cells. Methods: Expression of CCN2-mRNA and CCN2-protein were examined in osteoblates in the presence of VEGF by Real time PCR and ELISA. Generation of osteoblast-conditioned supernatant. HUVECs were divided into three groups: Control group, OSE group, VEGF-OSE group (n=3). The chemically synthesized CCN2-siRNA was transfected into osteoblasts. The ability of cell migration was analyzed by the Transwell assay. The capability of cell to form capillary-like tubes in vitro was assessed on Matrigel assay. Results: VEGF increases the expression of CCN2 mRNA and protein in osteoblasts in a time- and dose-dependent manner. CCN2 promotes HUVEC migration and capillary tube-forming in vitro（P<0.05）. These effects were prevented by an antibody against CCN2 or by small interfering RNA-mediated knockdown of osteoblast CCN2 (P<0.05). Conclusion: VEGF-induced up-regulation of CCN2 in osteoblasts mediates the ability of migration and angiogenesis in HUVEC.

Key words: VEGF, CCN2, Osteoblasts, Human umbilical endothelial cells, Angiogenesis