Construction of tissue engineered bone modified by bone morphogenetic protein-2 and bone morphogenetic protein-7 genes

Objective To investigate the feasibility and advantages of constructing a novel tissue engineered bone through lentivirus transfection using β-tricalcium phosphate (β-TCP) and adipose derived stem cells (ADSCs) and modification with human bone morphogenetic protein 2 gene (BMP-2) and human bone morphogenetic protein 7 gene (BMP-7).Methods ADSCs derived from SD rats were passaged into the third generation before they were randomly divided into 4 groups:BMP-2 (Lv-BMP-2-transfected ADSCs),BMP-7 (Lv-BMP-7-transfected ADSCs),BMP-2+BMP-7 (ADSCs cotransfected by Lv-BMP-2 and Lv-BMP-7) and control (non-transfected ADSCs).The ADSCs at a concentration of 1 × 106/30 μL were seeded onto the β-TCP for compound culture in vitro.PicoGreen dsDNA assay evaluated the growth of ADSCs.The alkaline phosphatase (ALP) activity of ADSCs was measured.Alizarin red S staining and real-time PCR were used to test the osteoblast activities of ADSCs.Results After the ADSCs were seeded onto the scaffolds for 0 to 14 days,a similar trend was observed in the 4 groups regarding changes in the DNA amount.At 14 days after cell seeding,the BMP-2,BMP-7 and BMP-2 + BMP-7 groups had more calcific nodules than the control group,with the highest number in the BMP-2 + BMP-7 group.The ALP,mRNA and protein expressions of osteopontin and osteoealcin in the BMP-2 + BMP-7 group were significantly higher than those in the other 3 groups (P ＜ 0.05).X-ray at 6 weeks postoperation showed bone defects were almost healed in the BMP-2 + BMP-7 group but not in the other 3 groups.HE staining showed complete cortex bone and bone marrow in the BMP-2 + BMP-7 group but only a little amount of bone trabecula,cortex bone and bone marrow in the other 3 groups.Conclusions Tissue engineered bone can be constructed using β-TCP combined with ADSCs co-transfected with BMP-2 and BMP-7.As such tissue engineered bone has a great advantage of remarkably increased capability of osteogenesis,it can be used as a new means of treating bone defects. Key words: Bone morphogenetic proteins;  Adipose tissue;  Mesenchymal stem cells;  Tissue engineering;  Bone defects