Improving Effect Of Adiponectin On Mice Femoral Fracture Healing And Its Mechanisms

Object Establish ideal femoral fracture model in mice, in order to observe the function of adiponectin on femoral fracture healing, and explore the possible mechanisms of adiponectin in mice fracture model.Methods C57BL/6J mice were used to establish the femoral fracture model. Mice were divided into 12 groups depending on the drug categoriesy, durations and doses. Mice cancellous bone volume, the thickness of cortical bone, biomechanical strength and the changes of the fracture sites were observed. Blood indicators were tested by ELISA, expressions of BMP-2 in fracture site were tested by Western Blotting analysis, and the formations of the bone callus were measured by Masson trichrome.Results 1.Fracture site physical, HE staining and Micro-CT reconstruction diagram showed the fracture line began to blur in adiponectin group and BMP-2 group at 2 weeks, and almost invisible in 4 weeks. Fracture healing in adiponectin group and BMP-2 group are better than control group.2.Biomechanical analyses:maximum load, maximum radial degrees, elastic radial degree and rigidity by mechanical testing were higher in adiponectin group and BMP-2 group compared with control group (p<0.05). 3.Micro-CT scanning:The cortical continuity and cancellous bone structure of adiponectin group and BMP-2 group were better than the negative control group(p< 0.05), furthermore BMD and BV/TV in adiponectin treatment group and BMP-2 group were higher too.4.Blood indicators:No statistic significant difference(p> 0.05) could be found in BMP-2, adiponectin, OCN, IL-1, IL-6, IL-17 and ROS between different groups. In 2,4weeks, the expression level of OPG in each group increased.4 weeks later the levels of OPG in adiponectin(2mg/kg) group was higher than the other groups. In 6 weeks the expression of OPG decreased(p<0.05).5.Western Blotting analyses BMP-2 expression of BMP-2 group was highest among all groups at 2 weeks, while the BMP-2 expression adiponectin(2mg/kg) group became the highest at 4 and 6 weeks. 6.Masson trichrome:The bone callus of adiponectin group and BMP-2 group were more significant than the negative control group at 2 weeks, and the bone shaping looked much more better from 4 weeks.Conclusion Adiponectin could significantly improve bone callus formation and cortical continuity; Increase the femur’s strength, elasticity in fracture healing; Elevated bone density; Improve cortical bone and cancellous bone micro-structure in fracture site. Production of BMP-2 in fracture site might be the possible underlying mechanism of adiponectin protection effect in femoral fracture.