| Objective:In the experiment, we established the rabbit models of mandibular fractures and glued by fibrin glue(FG), and then detected the expression of VEGF in osteotylus by real-time PCR and to observe ossification during the process of fracture healing. To studies it's mechanism for promoting fracture healing and possibility which applies in the fracture of jaw bones.Methods:We builded the fracture surgery models of rabbit bilateral mandibular, One side of the bone fragment fixed with fibrin glue (experimental group), another without treatment (control group). Three rabbits were killed at 8h,-3d,-7d,-14d, and 21d after operation, osteotylus tissue of experimental group and control group was collected, then the expression of VEGF was detected respectively by real-time PCR(RT-PCR) Two rabbits were killed at 3d and 14d, respectively observed the situation of fracture healing by visual study.Three rabbits were killed at 7d and 14d after operation, respectively observed the situation of fracture healing by HE staining.Results:1. Rabbit mandibular gross observation:In 7d after operation, bone surface slightly hunched and sequential, the fracture line were visible in the control group and experimental group.There was nonunion in one case from control group,the other cases were malunion.Compared with control group, there was a good soft tissue healing and sclerotin was approximate contiguous, the fracture line was not obvious. In 21 d after operation,Fracture were preliminary healing in experimental group.Bone fragment was necrotic in one case from control group,the rest fragment connect malposedly and were around with thicker fibrous tissue.There were continuous bone,osteolylus were increase obviously,fracture line was blur in the experimental group.2. Histological (HE staining) results:In 3d after operation,the fracture fragments shows an orderly connection,fracture healing with a large quantity of fibroblasts and capillaries,small quantity of macrophages.There were visible osteoblast deposition and more cellular components at fracture fragment. The hemorrhage phenomenon is obvious at bone fracture place in control group,drifts away massively the necrosis blade; In 14d after operation, the micrangium forms well in Fiber structure of experimental group,the osteoid can be seen parallel to the fracture line,osteoblasts were seen around closely packed monolayer.There was clear osteoplasis phase within the fibrous tissue between the broken ends of fractured bone,became fibrous union. But a lot of inflammatory cells were infiltrating between the broken ends of fractured bone from control group.The structure of fibrous tissue was disorderly and there were a small quantity of micrangium and fibrocartilage.3. PCR results:VEGF expression:Amount of VEGF expression were basic propter in the experimental group and control group on 8h after operation (p> 0.05). Amount of VEGF expression in experimental group was 1.39 times than what in the control group (p<0.05) on 7d, VEGF expression reached the peak in the control group and experimental group and expression amount in experimental group was 1.46 times than what in the control group (p<0.05) on 14d. Amount of VEGF expression which were basic propter in the experimental group and control group decreased after 14d (p> 0.05).Conclusion:The FG could be promote bone-formation phenomenon to fracture healing. VEGF expression of callus tissue in fracture place increased during early fracture healing may be one of molecular mechanism of promoting fracture healing. |
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