OBJECTIVETo observe the heterotopic osteogenesis of autogenous marrow stromal cells loading on porous calcium phosphate ceramic scaffolds with rhBMP2 gene transfection in a Sprague-Dawley rat model.

METHODSAutogenous marrow stromal cells were obtained from left femurs and tibias of 20 male adult SD rats under general anesthesia and sterile condition and cultured in alpha-Minimal Essential Medium supplemented with 15% fetal bovine serum. RhBMP2 gene was transfected into stromal cells by means of LipofectAMINE 2000 reagent five days after primary culture. The stably gene expressive cells were selected with G-418 for 14 days and mixed with stromal cells without transfection. The mixture cells were seeded and subcultured for another 10 days in porous calcium phosphate bioceramic that had been subjected to surface-modification via soaking in human plasma fibronectin. The cell-ceramic compound was implanted subcutaneously and intramuscularly in the corresponding rat. Lab animals were sacrificed at two-week intervals till twenty weeks postoperatively and the involved samples were removed.

RESULTSMorphologic and histological study demonstrated that cell-ceramic compound had an ability of heterotopic osteogenesis, which was similar to that of autogenous osteoblasts in previous study.

CONCLUSIONIt seems that autogenous stromal cells with rhBMP2 transfection acts as a bioreactor promoting proliferation and differentiation of stem cells when they are replanted into the corresponding animals.