RESUMO
OBJECTIVE： To investigate the effects and its mechanism of calcium phosphate bone cement （CPC） loading total flavonoids of Davallia mariesii on osteogenic differentiation of induced membrane in rats. METHODS： Drug-loading CPC and drug-loading polymethyl methacrylate （PMMA） cement were prepared with the contents of Qianggu capsules （total flavonoids of D. mariesii as active ingredient） using CPC and PMMA cement as carrier. Totally 64 male SD rats were randomly divided into drug-loading CPC group， drug-loading PMMA cement group， no-drug CPC group， no-drug PMMA cement group， with 16 rats in each group. The femur of rats was separated and osteotomized to prepare bone defect model， and then the corresponding bone cement was implanted. Four weeks after modeling， the induced membranes of rats were cut and protected. Bone cement was taken out and autogenous cancellous bone was implanted. At the 4th week after modeling， X-ray photographs were taken on the hind limb bones of rats. At the 4th week after modeling and 6th week after bone grafting， induced membranes and new bone were taken from the bone defect area of rats respectively. HE staining was used to observe the morphology of induced membrane， and the width of bone rabecular and the number of osteoblasts of new bone tissue were measured. Immunohistochemistry was used to detect the protein expression of BMP-2 and VEGF in induced membrane. Western blotting assay was used to detect the protein expression of Smad1， Smad4 and Smad7 in new bone. RESULTS： Compared with other 3 groups， the degradation of bone cement in drug-loading CPC group was more obvious in the bone defect areas， which showed that the formation of induced membrane was observed and the bone defect areas were smaller； capillary endothelial cells were abundant and orderly arranged in the induced membranes， and the width of bone trabeculae and the number of osteoblasts in the new bone tissue increased significantly （P＜0.05）； the protein expression of BMP-2 and VEGF in the induced membrane， the protein expression of Smad1， Smad4 and Smad7 in new bone were increased significantly （P＜0.05）. CONCLUSIONS： CPC loading total flavonoids of D. mariesii promotes the formation of induced membrane osteoblast in bone defect model rats， which may be associated with regulating osteoblast differentiation by activating BMP-2/Smad pathway； at the same time， it can promote bone healing by promoting the differentiation of vascular endothelial cells， accelerating the formation of capillary network and increasing the expression of vascular endothelial cells.
RESUMO
ObjectiveTo explore the effect of the calcium phosphate cement (CPC) /calcium polyphosphate fiber (CPPF) composites mixed with different proportion of minimal morselized bone on repair of bone defect in vivo. MethodsA total of 36 New Zealand white rabbits were completely randomly designed into A, B, C, D groups and their bilateral radial bone defect model was prepared. The minimal morselized bone (300-500 μm in diameter) was made from the iliac of those rats. The CPPF and CPC were evenly mixed into CPC/CPPF composites which were divided into four groups in accordance with the CPPF weight O, 10％, 30％ and 50％ in CPC/CPPF composite. The CPC/CPPF composites of the four groups was mixed with the minimal morselized bone with ratio of 6:4 and then the mixture was implanted the bone defect of the rabbits in four groups. The gross, X-ray and histological observations were done at four and eight weeks. The biomechanical test was performed at eight weeks. Results When CPPF occupies 30％ of the CPC/CPPF composite, the maximum compressive load and bending loads were better than those in the other groups ( P ＜ 0.05 ), when the histological observation showed the most tight link between the artificial composite and the bone interface and the closest similarity between material degradation rate and the ossification rate, with the best osteogenesis and the optimal ratio.ConclusionThe repair of bone defect can attain the optimal outcome through adding a certain ratio of minimal morselized bone into the CPC/CPPF to adjust the degradation rate of composites.