The Experimental Study Of The Tissue Engineered Bone On Reconstructing Mandibular Bone Defect

Objective: To induce mandibular bone regeneration and repair of bone defects using the tissue en-gineered bone and evaluate their osteogenic activities. Methods: 12 dogs were randomly divided into 4 groups for detailed study. Bone defects with size of 30mm 12mm were made at the mandibular body of dogs on two sides. The defect on one side was implanted with various composite and the other was not implant as control side. The marrow stromal stem cells of dog were cultured in DMEM containing 100ml/L fetal bovine serum and induced to differentiate towards osteoblasts. Then the cells were seeded onto absorbable polylactic acid compounded with rhBMP-2, then the composite was implanted into the mandibular bone defectrgroup A with PLA/rhBMP/BMSC, group B with PLA/rhBMP, group C with PLA /BMSC and group C with PLA. At 2, 4, 8 weeks after implantation , the effectiveness of bone formation was evaluated by means of gross, roentgenographic, histological observation and scanning electronic microscope ( SEM) examination . Result: The primary BMSC adhere to the bottom after 4 hours and proliferate to single layer with long-spindle shape. The shape of passage BMSC changed to various, mineralization was detected by Von Kossa staining techniques. At 4,8 weeks , bone traboeula was obserbed to pass the defect by X-ray and the calicified shadow was observed in the experimental group. After 4 weeks , osteoid tissues were observed by histology analysis,the new bone began to form in the defects. After 8 weeks, bulk bone could be obviously observed and many osteoblasts could be seen in the bone matrix by SEM examination, most of the PLA in the defects were already biodegraded, the defects were restored with new bone. Gross inspection showed that no demarcation between the region of the defect and the normal bone, the consistency of engineering bone similar to the normal bone. The results in group PLA/rhBMP/BMSC were better than those of other groups. Group three and group four were only fibrous tissue on the defects. Conclusion: The marrow stromal cells from dogs could be promoted to the osteoblastic phenotype of the cells in vitro by multiplied -glycerophosphate and dexamethasome. Exogenous BMP could accelerate BMSC proliferation and induce bone reconstruction compounded with degradable PLA.PLA/rhBMP/BMSC could induce mandibular bone cells regeneration and could be used as a good material for bone defect reconstruction.