ABSTRACT
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.
ABSTRACT
BACKGROUND: Osteoporosis is a serious threat to the health and quality of life in the elderly. It is important to establish an ideal experimental animal model to study the etiology and treatment of osteoporosis.OBJECTIVE: To establish a rat model of osteoporosis induced by different dosages of retinoic acid, thus selecting the optimal dosage.METHODS: Eighty female Sprague-Dawley rats were randomly divided into control, low-, middle- and high-dosage groups based on body mass (n=20 per group), The rats in the latter three groups were induced with 80, 100, and 120 mg/(kg?d) retinoic acid via gastric lavage for 14 days.RESULTS AND CONCLUSION: Compared with the control group, the bone mineral density, number of osteoblasts and osteoclasts, and bone microarchitecture in the low-dosage group showed no significant changes, while there were significant decrease in the serum level of calcium and bone mineral density of femur, significant increase in the number of osteoclasts at the femur and significant changes in the femoral microarchitecture in the middle- and high-dosage groups, especially in the middle-dose group. To conclude, 120 mg/(kg?d) retinoic acid via gastric lavage for 14 days can induce a stable osteoporosis model in rats.