Variation of bone morphogenetic protein-2 and vascular endothelial growth factor after bone defect filled with tricalcium phosphate / 中国组织工程研究

ABSTRACT

BACKGROUND:Currently, bone graft is mainly used for repair of bone defects, and tricalcium phosphate is the most used artificial bone material. But the effectiveness of the tricalcium phosphate bone graft is stil controversial, and there is also no detailed report about its function during the healing of bone defect. ＜br> OBJECTIVE:To observe the concentration changes of bone morphogenetic protein-2 and vascular endothelial growth factor as wel as bone healing after tricalcium phosphate graft in bone defects. ＜br> METHODS:Forty-eight C57 mice were randomly divided to experimental group and control group. A 2-mm-long diaphyseal segment and periosteum from the middle of the right femur was cut to prepare unilateral bone defect models. Tricalcium phosphate bone graft was used in the experimental group, and no bone graft in the control group. During the fol owing 4 weeks, X-ray examination was done once a week to observe the bone healing, and then the animals were executed for col ecting samples in the graft area. The concentrations of bone morphogenetic protein-2 and vascular endothelial growth factor in samples which were taken from the bone graft area were determined by using ELISA assay. ＜br> RESULTS AND CONCLUSION:X-ray films showed that 2 weeks later, bone fracture healed mostly in the experimental group except a smal part of cortical bone;3 weeks later, bone fracture was basical y healed, and only a smal amount of tricalcium phosphate remained;4 weeks later, bone fracture was completely healed, and the cal us grew obviously, and the tricalcium phosphate was nearly absorbed. In the control group, the fracture line was stil visible at 1-2 weeks, but it became vague at 3 weeks;then, the fracture was healed at 4 weeks except some of the cortical bone. The levels of bone morphogenetic protein-2 and vascular endothelial growth factor were significantly higher in the experimental group than in the control group at different time points (P＜0.05). These results suggest that tricalcium phosphate bone graft can up-regulate the expression of bone morphogenetic protein-2 and vascular endothelial growth factor and accelerate bone healing.