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Objectivev: To study hBMP-4 gene therapy combined with tissue-engineering techniques for improving osteogenesis. Materials and Methods: pEGFP-hBMP-4 mammalian plasmid was constructed by subcloning technique and confirmed by DNA sequencing. Bone marrow stromal cells (bMSCs) obtained from rabbits were cultured and transfected with either pEGFP-hBMP-4, pEGFP or left unifected in vitro. Transfer efficiency was detected through the expression of enhanced green fluorescent protein (EGFP). The cells of the three groups were combined with natural non-organic bone (NNB); a porous hydroxyapatite implant with a diameter of 6 mm and a height of 3 mm, at a concentration of 50 X 106 cells/mL. Four weeks after their subcutaneous implantation into nude mice (six implants per group), the implants were evaluated with histological staining and computerized analysis of new bone formation. Results: pEGFP-hBMP-4 expression plasmid was successfully constructed. Under optimal conditions, gene transfer efficiency was 30%. In vivo, NNB alone did no induce bone formation. The new bone area in the untransfected bMSCs group was 45.9 ± 8.3%, and pEGFP group was 50.3 ± 11.4%, while in the pEGFP-BMP-4 group it was 68.8 X 16.1% (p<0.05). Conclusion: The mammalian hBMP-4 expression plasmid was successfully constructed and a comparatively high transfer efficiency was achieved. In vivo results suggested that the transfection of bMSCs with hBMP-4 might be suitable for bone tissue engineering applications.
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