Experimental Study On Biological Repairing For Skull Defect

Object: To set up animal model of standard skull defect of New Zealand rabbit, and rapairing skull defect by transplanting porous inactive xenogenic bone flap to compound bone marrow-derived osteoblast. To study the feasibility of this experiment and clarify the mechanism through detect the vitro-cultural osteoblast and histology observation electron microscope observation immunohistochemical examination of endogenous BMP-2 and bone density of the repairing site of skull defect. Materials and Methods: 100 adult New Zealand rabbits,with an average age of 4 months and no sex restriction, were randomly divided into two groups: (l).the experiment group(50 rabbits), rapairing skull defect by transplanting porous inactive xenogenic bone flap to compound bone marrow-derived osteoblast; (2).the routine control group(50 rabbits), rapairing skull defect just by transplanting porous inactive xenogenicbone flap. We check the osteoblast endogenous BMP-2 with immunohistochemistry at 10 15 days respectively, and observe the histology electron microscope and bone density of the repairing site of skull defect at 2 4 8 12 and 16 weeks respectively, each time 5 rabbits. Result: bone marrow-derived mesenchymal stem cells can convert osteoblast through vitro-culture in conditioned medium. We have confirmed them through detect AKP. There are 50 rabbits in the experiment group and the routine control group, 1 rabbit have infected and 1 rabbit death of the total, others have obtained satisfactory result in the area of skull defect. The observation of results: 1. Gross morphology: two groups have not significant difference. At 16 weeks after operation, the grafted areas of two groups were substituted with new born one and it was inosculated with skull. 2. Histological and Electron microscope observation: the pores of dead bone have filled with generous osteoblasts in the experiment group, the osteoblasts generation and secrete extracellular matrix. We can see the new blood vessel and bone lacuna. There are generous center of ossification, the osteoblasts are fixed in bone matrix and change to bone cell, this form the un-ripe woven bone. When mineral matter and organics increased in the bone matrix, the un-ripe woven bone substitute with lamellar bone, and the repair of defect of skull have finished. The cell populations, activity of ossify and vascularize in the routine control group are few than the experimentgroup, as well the bone formation is 4-6 weeks slower than the experiment group. 3. immunohistochemical examination of endogenous BMP-2: at 10 and 15 days after operation, the trachychromatic brown beads were observed in the cytoplasm of osteoblasts in the experiment group, the masculine cells and the expressive intensity were stronger than the routine control group. 4. Determination of bone density: the result of the bone mine content(BMC) and bone density(BMD) in the experiment group were lower than the normal group, but the difference have not statistically significant. The result of the bone mine content(BMC) and bone density(BMD) in the routine control group were lower than the normal group and the experiment group, and the difference have statistically significant.Conclusion: 1. the bone marrow can become the frequently used seeds cell of bone organization project. 2. the porous inactive xenogenic bone flap can become the frequently used support material of bone organization project. 3. intramembrane forming bone is the main style of repairing the defect of skull by transplanting porous inactive xenogenic bone flap to compound bone marrow-derived osteoblast, and the activity of ossify not only speed but also quality is outstrip the simple porous inactive bone flap. The BMC, BMD and appearance were achieved the level of normal cranial bone and the requirement of biological repair, also have clinical application value.