Repair of Mandibular Defects with Tissue-Engineered Bone in Rabbits

Objective: To investigate the osteogenic capability and effect of tissue engineered bone in repairing mandibular defects in rabbits, which was constructed by autogenous bone marrow derived osteoblasts and allogenous demineralized bone. Methods: The osteoblasts isolated from rabbit bone marrow were cultured and seeded into the demineralized bone to construct tissue-engineered bone in vitro. The tissue-engineered bone and demineralized bone were used to repair the mandibular defects in 20 rabbits, respectively. The bone formation was evaluated grossly, radiographically, histologically at 2,4,8,12 weeks after transplantation. The density of newly-formed bone in experimental and control groups were recorded and compared using computer analysis system on the X-ray image. Results: Gross observation showed that the formation of new bone was obviously accelerated in experimental group at different observation periods. At the end of experiment, the bone defect was completely filled with new bone in experimental side. In the control side, however, partial defect was still remained at the inferior margin. There was statistically significant difference (P>0.05) in the density of the experimental defect at each time point within the four groups. Histologically, in the 2-week implant of experimental side, there was obvious formation of new bone with large amounts of bone trabecula from the host bone penetrated into the implant. In the 4-week and 8-week implant of experimental sides, the new trabecular bone developed towards to lamellar bone. At the 12th week, the new bone was similar to host bone. In control implant, the major osteogenic pattern was "creeping substitute". There was a large amount of fibrous tissue in newly-formed bone. Conclusion: The tissue-engineered bone constructed by autogenous bone marrow derived osteoblasts and allogeneic demineralized bone has the capability of osteogenesis, osteoconducion and osteoinduction with better osteogenetic effect and quality than demineralized bone implant, and is an ideal graft in repair of mandibular defects.