Comparisons of induced membrane vascularization and osteogenic factor expression in different tissue sites / 中国组织工程研究

ABSTRACT

BACKGROUND: Studies have found that polymethylmethacrylate bone cement implanted in the subcutaneous region, muscle and other parts can form induced membrane. The induced membrane favors vascularization and secretes multiple osteogenic factors. OBJECTIVE: To investigate the differences in the level of vascularization and the expression of osteogenic factors in the induced membrane among subcutaneous region, muscle and femoral bone defects. METHODS: Thirty-six male SD rats (purchased from the Experimental Animal Center of Guangzhou University of Chinese Medicine) were randomly divided into three groups (n=12/group). Polymethylmethacrylate antibiotic cement spacers were implanted in the subcutaneous tissue, muscle and femoral bone defects of the hind limbs. At 6 weeks after implantation, the induced membrane around the bone cement was removed. The change in membrane morphology was observed by hematoxylin-eosin staining. Expression of bone morphogenetic protein-2, transforming growth factor-31 and vascular endothelial growth factor in the induced membrane was detected by western blot, RT-qPCR and immunohistochemistry. This study was approved by Animal Ethics Committee, Guangzhou University of Chinese Medicine, China (approval No. 20181101006). RESULTS AND CONCLUSION: Hematoxylin-eosin staining showed that induced membrane formed in each group. The number of vessels in the outer layer of the membrane tissue section was higher in the femoral bone defect groups than that in the muscle and subcutaneous tissue group. The number of fibroblasts and myofibroblasts in the inner layer close to the bone cement was higher in the femoral bone defect group than in the muscle and subcutaneous tissue groups. Immunohistochemical staining revealed that bone morphogenetic protein-2, transforming growth factor-31 and vascular endothelial growth factor expression levels were highest in the femoral bone defect group and lowest in the subcutaneous tissue group. Western blot and RT-qPCR showed that bone morphogenetic protein 2, transforming growth factor 31 and vascular endothelial growth factor expression levels were significantly higher in the femoral bone defect group than in the muscle and subcutaneous tissue groups (P < 0.001). These findings suggest that different surrounding tissue conditions have different important influences on tissue structure and osteogenic factor expression in the induced membrane. Polymethylmethacrylate bone cement implanted in the femoral bone defects can improve the quality of induced membrane formation, lead to a larger amount of newly formed vessels and higher osteogenic factor expression in the induced membrane.