Experimental Study On Using Tissue-Engineered Bone To Repair Radial Bone Defects In Rabbit

Objective : To discuss and understand the ability of using tissue-engineered bone (homogenous allogenic biological bone material and bone marrow stromal cells constitute )to repair long defects in radial bone of rabbit.Methods :Bone marrow harvested from the shaft of femur of rabbit, and by using density gradient centrifugation to isolate bone marrow stromal stem cells (BMSCs). At the second passage ,the BMSCs were culture the condition of induction and differentiated in vitro .The expressions of alkaline phosphatase(ALP) and type I collagen as well as the formation of calcium nodules were detected. Cultured BMSCs were collected and marked by 5-bromo-deoxyuridine (BrdU), Then added to homogenous allogenic biological bone material to form tissue-engineered bone. Experimental group of 6 rabbits with 10mm periosteal bone defect of right and left middle radius were transplanted with tissue-engineered bone. Control group of 6 rabbits with same bone defect size were transplanted with material of natural bone and other 6 rabbits were transplanted with autogenous bone graft. Blank group of 6 rabbits with Rt & Lt radial bone defects at the same location and size were left without any transplantation. Post-operative X-ray at 2,4,6,8,12 weeks intervals were taken, gross observation and histological examination at 6,12 weeks were observed and immunohistochemical detection of BrdU at six weeks was documented. Results : fracture line disappeared with complete cortical bone formation after 8 weeks in both experimental group and autologous bone group, by 12 weeks complete healing of bone defect and bone marrow recanalization occurs. While in material of natural bone group, fracture line disappeared after 8 weeks with dense bone callus at the site of bone defects, and by 12 weeks bone marrow still not recanalized. Blank group at 12 weeks, the two bone ends shows atrophy and sclerosis with closed medullary canal and nonunion. Through 6,12 weeks intervals, histological sections study shows: early appearance of fibrous and lamillar bone with better bone remodeling in the experimental and the autologous bone groups. At 6,8,12 weeks X-ray film evaluation, statistical analysis showed no significance in the experimental and the autologous bone groups compared to significance found with material of natural bone group.Conclusion: Results of repair of bone-defects using tissue-engineered bone found to be better than using material of natural bone. and similar with using autologous bone, hence it can substitute the use of autogenous bone for repair of bone defects.