Objective:To investigate VEGF expression in NIH3T3 cells infected by adenovirus containing hVEGF165 gene and its influence on proliferation of NIH3T3 cells,and to observe the expression of hVEGF and its angiogenic effect in vivo.Methods: Adenoviral vector containing hVEGF165 gene was constructed and was used to infect NIH3T3 cells.The infection efficiency of adenovirus vector was examined by immunofluorescence and flow cytometry.Expression of VEGF in NIH3T3 cells and its levels in the culture medium were examined by immunohistochemical (IHC) staining,RT-PCR,and ELISA.The infected NIH3T3 cells were implanted in skin defect at rat back and the acellular dermis on the wound was obtained one week later; the expression of hVEGF was detected by IHC in the dermis and the density of vessels was determined under microscope.Results: NIH3T3 cells were effectively transfected by adenovirus containing VEGF gene in vitro,the transfection efficiency was in a dose-effect manner with multiplicities of infection (MOI) of the adenovirus.When MOI was 100,the infection efficiency was more than 95%.The expression of VEGF mRNA and protein was detected by RT-PCR and IHC 24 h after transfection.ELISA result showed that the high level of VEGF on the 3rd day after transfection and the level reached its peak 7 d after infection (1 052 pg/ml); VEGF expression was detectable 13 d after transfection.MTT assay demonstrated no significant difference in cellular proliferation between the transfection and non-transfection group.Expression of hVEGF was also detected in vivo in mice,and the density of vessels in the experimental group was significantly higher than that in the control group （P<0.01）.Conclusion: Adenoviral vector can effectively transfect VEGF gene into NIH3T3 cells; VEGF gene can be detected in vitro and in vivo; and it can promote neovascularization in the transplanted tissues.