| OBJECTIVE:To make a rabbit model of Perthes disease and to explore the change and its significance of vascular endothelial growth factor(VEGF) expression in the femoral head. To Analyse the important role of VEGF in repairing and reconstructing femoral heads in Perthes disease. To apply three different surgical methods (decompressing in elder pith, resecting synovium and transplanting autogeneic cancellated bone) to treat Perthes disease model and to appraise the effect of the three methods by observing and comparing VEGF expression.METHODS: (1)24 three-month-age New Zealand rabbits were randomly divided into experimental group and control group. 16 rabbits were in experimental group and 8 rabbits were in control group. A rabbit model was made by operative method after left ligmentum teres was divided and retinacular bood supplies of femoral head were resected. The rabbits were killed in batch at the time of the first, second, fourth, eighth week in each group respectively. Evaluated by X-ray, femoral head specimens were sudied by histological examination, VEGF immunohistochemistry and VEGFmRNA in situ hybridization. (2) 36 three-month-age New Zealand rabbits were randomly divided into four groups. There were 9 rabbits in each group. Group A: Establishing Perthes model. Group B: Establishing Perthes model and decompressing in elder pith. Group C: Establishing Perthes model and resecting synovium. Group D: Establishing Perthes model and transplanting autogeneic cancellated. A rabbit model was made by operative method after left ligmentum teres was divided and retinacular bood supplies of femoral head were resected. Treat group B,C,D on different surgical methods 2 weeks after establishing Perthes model . Three rabbits were killed in batch at the time of the fourth, sixth, eighth week after establishing Perthes model(the second, fourth, sixth week after treatment) in each group respectively. Femoral head specimens were studied by histological examination and VEGF immunohistochemistry.RESULTS: (1) The rabbit models were made by operative method all successfully. The view in general: The femoral heads in control group at every time had no necrosis changes. The femoral heads in experimental group became coarse, tarnish and smaller ,and even collapsed. The X-ray picture of femoral heads: The intensity of femoral head at 4th and 8th week in experimental group became higher than that in control group. The observation in HE staining: The femoral heads in control group at every time after operations had no necrosis changes.New vessels and granulation tissues grew into the necrosis part in experimental group at 4th and 8th week after operations.Newly formed bone could be seen taking part in repairing. Immunohistochemistry staining:In the epiphyseal cartilage of the femoral heads in control group, an intensive VEGF immunoreactivity(VEGF-IR) was found in the hypertrophic zone with a low level of VEGF-IR in the proliferative zone. At 1st week after operation, the percentage of VEGF+ cells present in the proliferative zone of the femoral heads in experimental group was increased compared with the femoral heads in control group. The percentage of VEGF+ cells found in the hypertrophic zone of the femoral heads in experimental group was significantly decreased compared with the femoral heads in control group. At 8th week after operation, VEGF-IR was observed throughout the epiphyseal cartilage surrounding the bony epiphysis in the femoral heads in experimental group. The percentage of VEGF+ cells present in the proliferative zone of the femoral heads in experimental group was significantly increased compared with the normal heads. The hypertrophic zone of the femoral heads in experimental group had a similar percentage of the VEGF+ cells as the femoral heads in control group when endochondral ossification was restored at 8th week. The ratios of VEGF+ cells in the proliferative zone of femoral head in experimental group at 1st,2nd,4th and 8th week after operations had statistical significances with that in control group(p﹤0.01,α=0.05); the ratios of VEGF+ cells in the hypotrophic zone of femoral head in experimental group at 1st,2nd and 4th week after operations had statistical significances with that in control group(p﹤0.01,α=0.05). In situ hybridization : The results of in situ hybridizition were similar to that of histology. VEGF mRNA expression in the hypertrophic zone of epiphyseal catilage after necrosis became lower. VEGF mRNA expression in the proliferative zone of epiphyseal catilage after necrosis increased. VEGF mRNA expression in the hypertrophic zone of epiphyseal catilage in experimental group could be seen again after endochondral ossification was repaired. (2)The VEGF-IR each time in group B and C was of no obvious difference.In group D, VEGF-IR in proliferative zone and hypertrophic zone of femoral heads at 4th week were higher than that in group A.The observation at 6th week was similar with that at 4th week. At 8th week, VEGF-IR was observed throughout the epiphyseal cartilage surrounding the bony epiphysis in the femoral heads in group D. The percentage of VEGF+ cells present in the proliferative zone of the femoral heads in group D was significantly increased compared with group A. The hypertrophic zone of the femoral heads in group D had a higher percentage of the VEGF+ cells as the femoral heads in group A when endochondral ossification was restored at 8th week. There was no significant difference. The ratios of VEGF+ cells in the proliferative zone and hypetrophic zone at each time were higher than any other group. And it was statistically significant(P﹤0.05,α=0.05).CONCLUSIONS: (1) Perthes model established on operational methods by resecting bood supplies of femoral head has similar characteristic with Perthes disease in X-ray and pathology. (2) It is possible that VEGF may act as a key regulator that couples angiogenesis, cartilage remodeling, and ossification after ischemic damage to restore endochondral ossification in the epiphyseal cartilage.It helps to treat Perthes disease to same extent.(3) Apply three different surgical methods (decompressing in elder pith, resecting synovium and transplanting autogeneic cancellated bone) to treat Perthes disease model and to appraise the effect of the three methods by observing and comparing VEGF expression. The results shows in experimental aspect that the method of transplanting autogeneic cancellated bone have determinate superiority than the other two methods.
|
PDF Full Text Request