Experimental Study On Biological Repairing For Skull Defect

Background: It has a hundred's history of repairing skull defect skull. Many skull repairing materials are available, but as far as now none can completely substitute skull as of the aspects of plastic, anti-impact, resistance, heat prevention and anti-magnetism, etc. Therefore somebody used the autologous skull flap to be buried subcutaneously and then transplant back to the patient after a period. But when burying and taking out the skull flap the patient has to undergo pains of twice operations, and the buried flap is easy to be absorbed to become thinner. Somebody else preserves the flap in the bone bane bank to be deeply frozen, and when in need take out to recover the temperature. But the need for freezing devices limited its popularization. During the operations for trauma of skull and brain or operations of brain tumor, in order to depress the intracranial pressure, the bone flap has to be removed and thus skull damage results. The bone flaps of these patients are usually intact, andthrowing away will be very pitiful. Repairing by the current popular titanium alloy in the second stage is too expensive and the physiological curvature is not perfect. However, it would be a simple, economical and practical way that using porous inactive autologous bone flap compounded with recombinant human bone morphogenetic protein-2 (rhBMP-2) for repairing skull defect. Up to now, there is few experimental study on this aspect, especially the relative basic researches about the mechanism of osteogenetic process. Nevertheless, the feasibility of this method had been proved by our clinical practices and good outcome had been achieved. So, we suppose that make the porous inactive autologous bone graft as the repairing scaffold material, rhBMP-2 can induce the expression of endogenous BMP-2 and TGF-pl, and induce the differentiation of osteoprogenitor cells to osteocytes in duramatter and periosteum, and achieve the biologic repair of skull defect at last.Objective: To study the feasibility of biologic repair and clarify the repairing mechanism through dynamically detecting the expression of osteoinductive factors (BMP-2 and TGF- P 1) and scaffold investigation on patholog calvaria defect regions. And later, we want to make sure whether the porous inactive autologous bone graft to be an ideal scaffold material for repairing the skull defect. Materials and Methods: 156 adult New Zealand Rabbits, with anaverage weight of 2.3?.3 kg and no sex restriction, were randomly divided into two groups: the immunohistochemistry group (120 rabbits) and the routine contrast group (36 rabits). Take out the bone flaps from the animal models with the help of high-speed cranial drill and boil them 30 minutes. Then, replace them back in two ways: the boiled autologous bone graft itself in the control group while in the experimental group, each bone grafts were combined with rhBMP-2 (0.5mg/bone flap). In the immunohistochemistry group, including 60 rabbits in sub-control group and 60 rabbits in sub-experimental group, we check the endogenous BMP-2 and TGF-pl of the grafted bone dynamically with immunohistochemistry at 25 days respectively, each time 5 rabbits. While in the routine checking group, including 6 rabbits in sub-control group and 30 rabbits in sub-experimental group, gross, histology and electro-microscope were checked 12 weeks respectively, each time also 5 rabbits. 1. Gross morphology:At 2 weeks after operation, when sacrifice, we can see that active prolifiration of the periosteum and dura in the receptors and tight join with the bone graft. Despire the mini-blood circulation and few fibrous connective tissues, the grafted bones wrere dead bone at all; at 4 weeks, the join was tighter and increases of blood circulation as well as fibrous connective tissues in the interfaces; at 6 weeks, more rich bloodcirculation were found, the interface is tough; at 8 weeks, the grafted bone was covered by connective tissue from periost and dura, on the transect, it joined with skull by cartilage, rich blood circulation in bone flap; at...