Abstract: AIM To transfect human hemo-oxygenase-1(hHO-1) gene into bone marrow Mesenchymal stem cell(MSC) via adenovirus (Adv) vector, so as to lay the experimental foundation for the therapy of cardiovascular disease. METHODS Bone marrow-derived MSC were separated and purified in vitro by Percoll density gradient centrifugation and screened by cell adhered to the bottom. MSC were transfected with different multiplicity of infection (MOI) of Adv-hHO-1-green fluorescent protein(GFP) after amplification, purification and identification. GFP expression was examined with fluorescence microscope and hHO-1 mRNA expression was observed with reverse transcription(RT)-polymerase chain reaction(PCR). 4’,6’-amidino-2’-phenylindol(DAPI) staining was used to observe the morphology of MSC after transfection. RESULTS PCR result showed a band of 555 bp DNA after Adv-GFP-hHO-1 amplification and purification. GFP was observed after 24 h transfection and the intensity of GFP expression enhanced in parallel with MOI. RT-PCR showed that the HO-1 mRNA expressed in different transfection groups and the expression also elevated in parallel with MOI. DAPI staining showed no obvious changes in the morphology of MSC. CONCLUSION hHO-1 gene is successfully transfected into MSC via Adv vector, which exerts no obvious adverse influence on the growth and proliferation of MSC. The transfection efficiency increases along with the increase of MOI.