Repalr of large-segmental femoral defects using lentivirus-mediated bone morphogenetic protein 2/bone marrow mesenchymal stem cells/demineralized bone matrix / 中国组织工程研究

ABSTRACT

BACKGROUND: Our research team has confirmed that compared to the adenoviral vector, transfection by lentiviral vector to rabbit bone marrow mesenchymal stem cells (BMSCs) is more effective that the expression of enhanced green fluorescent protein (EGFP)/bone morphogenetic protein 2 (BMP-2) can be persistent for a longer term. But further investigations are needed to explore whether BMSCs transfected with hBMP-2 through lentivirus combined with demineralized bone matrix (DBM) can promote bone defect repair. OBJECTIVE: To evaluate the effect of lentivirus-mediated hBMP-2/BMSCs/DBM (LV-hBMP-2/BMSCs/DBM) on the repair of large-segmental femoral defects and to explore the new treatments for large-segmental femoral defects. METHODS: Large-segmental bone defect models were made in the right femur of 48 New Zealand white rabbits by cutting the middle femoral bone and steel plate fixation. Then, animal models were randomly divided into four groups (n=12 per group) and implanted with nothing (control), DBM, hBMP-2/DBM, and LV-hBMP-2/BMSCs/DBM. Three rabbits from each group were sacrificed at 2, 4, 8 and 12 weeks after surgery to evaluate the repairing effect of femoral defects through hematoxylin-eosin staining, biomechanical analysis and radiological examination. RESULTS AND CONCLUSION: X-ray results revealed that osteotylus formed in all the four groups to different extents, and Lane - Sandhu X-ray scores were ranked as follows control group < DBM group < hBMP-2/DBM group < LV-hBMP-2/BMSCs/DBM group (P < 0.05). Findings from the three-point bending test showed that the maximum load of the LV-hBMP-2/BMSCs/DBM group was significantly higher than that of the hBMP-2/DBM group, but is still lower than that of the normal femur at 8 and 12 weeks after modeling (P < 0.05). Hematoxylin-eosin staining results revealed that a few trabecular bones arranged disorderedly and a large amount of fibrous tissues in the control group; the DBM scaffold was basically degraded in the DBM group presenting with partially disordered trabecular bones and a large amount of fibrous tissues; the trabecular bones in the bone defect area were basically connected into line to start the shaping of the cortical bone, and recanalization of the medullary cavity was insignificant in the hBMP-2/DBM group; new cortical bone formed in the bone defect area and the medullary cavity was recanalized in the LV-hBMP-2/BMSCs/DBM group. These findings indicate that LV-hBMP-2/BMSCs/DBM can produce a large amount of calluses, promote formation of new cortical bone, and promote bone conduction, bone induction and osteogenesis after implantation into the bone defect; and this material has good repairing effect on large-segmental femoral defects of rabbits.