〔Abstract〕 Objective To investigate the therapeutic effect of bone marrow mesenchymal stem cells(BMSCs) modified by bone morphogenetic protein(BMP)-2 gene combined with nano-hydroxyapatite(nHA)/polyamide 66(PA66) on femoral nonunion in rats. Methods Rat BMSCs were isolated and divided into the stent + BMSCs group,stent + BMSCs + rhBMP-2 group,and stent + BMSCs + Ad-BMP-2 group; human recombinant BMP-2(rhBMP-2) or adenovirus-infected BMP-2(Ad-BMP-2) vector was transfected into BMSCs and loaded onto nHA/PA66 stent materials. Flow cytometry was used to detect that BMSCs expressed specific surface markers. Cell proliferation was detected by MTT assay,related bioactive factors [platelet-derived growth factor(PDGF),transforming growth factor-β(TGF-β),vascular endothelial growth factor(VEGF),fibroblast growth factor(FGF),osteocalcin(OCN),osteonectin(ON) ] were detected by ELISA,alkaline phosphatase(ALP) activity was detected,and cell growth and adhesion were observed by scanning electron microscopy(SEM). In the atrophic nonunion model of SD rats,the stent + BMSCs + rh BMP-2 or stent + BMSCs + Ad-BMP-2 complex was implanted into the defect area,which was divided into the rh BMP-2 group and the Ad-BMP-2 group,and the therapeutic effect was evaluated by X-ray and MicroCT. Results The surface of the n HA/PA66 stent was smooth and porous,and BMSCs adhered well. Flow cytometry showed high expression of CD29 and CD90 and low expression of CD45 and CD34 in BMSCs. MTT showed that the cells proliferated rapidly after 72 h. Compared with the stent + BMSCs group and the stent + BMSCs + rhBMP-2 group,the ALP activity,the expressions of PDGF,TGF-β,VEGF,FGF,OCN,and ON in the stent + BMSCs + Ad-BMP-2 group were significantly up-regulated(P