Research On The Repair Of Bone Defect With Transplantation Of Ad-hBMP-2and Ad-hTGF-β1Cotransfected Bone Marrow Mesenchymal Stem Cells

Objectives:(1) To study the bone formation of the Ad-hBMP-2and Ad-hTGF-β1transfected into BMSCs.(2) To evaluate the repairing of segmental bone defects with hTGF-β1and hBMP-2co-transfected BMSCs and elucidate their relationship on bone formation.Methods:1.The identification and collection of bone mesenchymal stem cells modified by different target genes.(1) Sprague-Dawley rat BMSCs were isolated and cultured in DMEM medium supplemented with10%fetal bovine serum and identified by their character of differentiation.(2) When Ad-hTGF-β1and Ad-hBMP-2were transfected into BMSCs, the target genes in BMSCs were detected by GFP expression.(3) BMSCs included genes were collected and then transplanted into animal model.2.The bone formation of rat radius defects with BMSCs included different genes and collagen sponges(1)120Sprague Dawley rats of2months were randomly divided into5groups. A bone defect model (5mm in length) was made in the middle of left radius in each rat.Then every group was implanted something as following:group A:BMSCs co-modified with Ad-hTGF-β land Ad-hBMP-2/collagen sponges; group B:BMSCs modified with Ad-hBMP-2/collagen sponges; group C:BMSCs modified with Ad-hTGF-β1/collagen sponges; group D:BMSCs/collagen sponges; group E:saline water/collagen sponges.(2) Radiographic and Lane-Sandhu analysis of the operation limbs were performed to observe the repairing of radius defects at2,4,8and12weeks after operation.(3) At the end of2,4,8and12weeks after implantation, the rats were sacrificed and specimens were taken from the part of bone defect for histological examination and Nilsson analysis.(4) The effect of bone repairing was evaluated by gross observation at8and12weeks after operation.The operation radius were taken to make a biomechanical test at the end of12weeks.Results:(1) The GFP expression showed that the target genes were transfected into BMSCs in vitro.(2) The results of histological and radiographical examination showed that the bone defects of group A、B、C and D had different bone formation at different time after operation,compared to the control group.But the effect and volume of bone formation of group A were superior to those of the other4groups(P<0.05).(3) The results of the biomechanical test at12weeks showed:the biomechanical strength of radius in group A had no significant statistical difference with that of normal radius (P>0.05), but was better than that in group B and C (P<0.05). The biomechanical strength of group B was better than that of group C (P<0.05).Conclusion:(1) BMP-2and TGF-β1could promote repairing of segmental bone defects.(2) It has been observed the bone repair effect of co-treatment with BMP-2and TGF-β1is better than that of single BMP-2and TGF-β1at the bone-formation time,the quantity of new bone and the biomechanical strength. Therefore they have a good cooperative and synergistical relationship in the process of bone defect repair.