[Ectopic bone formation of bone marrow mesenchymal stem cells with gene transfer of human bone morphogenetic protein-9 gene in rabbit].

OBJECTIVE: To investigate the method combining hBMP-9 gene therapy with tissue-engineering techniques to improve osteogenesis in an ectopic bone formation model in rabbits.

METHODS: Rabbit marrow MSCs were transferred with BMP-9 gene by cationic liposome, and then were subjected to a series tests including fluorescent microscope, Flow cytometer (FCM), ALP activity quantitative assay and Von Kossa's calcium nodus staninig; MSCs transfected with BMP-9 gene successfully were seeded onto scaffolds of polylactide-co-glycolide (PLGA). Cell-matrix interactions were observed with fluorescent microscopy and scanning electronic microscopy. The tissue-engineered bones with MSCs seeded on PLGA were further subcutaneously implanted into rabbits. The implants were evaluated with histological staining at 4 and 8 weeks after surgery.

RESULTS: The gene transfer efficiency of MSCs transfected with BMP-9 gene was 34.15%, which was measured by FCM. The ALP activity of MSCs with BMP-9 gene transfer was higher than that of non-transfered cells (P < 0.01). The calcium nodus formation of MSCs was enhanced by the gene modification of BMP-9 gene. MSCs seeded onto PLGA showed high level of cell proliferation, and efficient synthesis of cell matrix was observed with, scanning electronic microscopy. In the ectopic bone formation model, new bone area was also significantly improved by BMP-9 gene modified MSCs seeded on PLGA (P < 0.05).

CONCLUSION: hBMP-9 gene modified MSCs could enhance ectopic new bone formation in rabbits. These results indicated that the strategy combining BMP-9 gene modified MSCs with PLGA might be suitable for bone tissue engineering applications.