Gelatin—chitosan Complex— Hydroxyapatite—minocycline Biomimetic Nanocomposite Materials Repair Rabbit Radius Defects

Background: Given that it has similar composition and structure with autologous bones, biomimetic nanocomposite material has a good prospect for application.Objective: To observe the capability of gelatin-chitosan complex-hydroxyapatite-minocycline biomimetic nanocomposite materials in the repair of rabbit radius defects.Process: Firstly, take 30 healthy adult New Zealand rabbits and make into critical-size lacunar bone defect about 15mm*6mm from the upper radius. Secondly, divide these samples into three groups randomly. They are experimental group(n=15), auto-SCT group(n=10) and blank group(n=5). Then, the gelatin-chitosan complex-hydroxyapatite-minocycline biomimetic nanocomposite materials developed by the research group are implanted into artificial radial bone defect in experimental group. Bone defect in blank group is implanted without any materials while in auto-SCT group radius from contralateral radius, as the same length as the composite, is implanted into artificial bone defect. Lastly, general observation, histological observation and X-ray observation are performed respectively at 2, 4, 8, 12 weeks postoperatively. The new nanocomposite material can obviously promote the repair of critical-size bone defect. The effects of repairing bone defect are almost the same between the new composite and autologous bone grafting.Result and Conclusion: Compared the four time points, it suggests that artificial bonedefect which were implanted the composite in experimental group has already merged after 8 weeks. And 12 weeks later, its shape is almost close to normal. Besides, through the histological observation in experimental group, the materials are absorbed at 4 weeks postoperatively. 8 weeks later, the new bone replaces the degradable materials. After 12 weeks, the bone defect is entirely repaired. While in the blank group, the bone defect is filled with fibrous tissues at 2, 4, 8, 12 weeks. Withthe time increasing, the X-ray plain film indicates that callus of bone defect in experimental group increased significantly. Until 12 weeks, the defect healed and the shape completed. In the blank group there is no obvious bone formation at 12 weeks, which leads to bone nonunion. However, in auto-SCT group, the defect healed completely and shaped well. To sum up, the experiments indicate that the new gelatin-chitosancomplex-hydroxyapatite-minocycline biomimetic nanocomposite material can obviously promote the repair of critical-size bone defect and the effect of repairing bone defect is basically the same with autologous bone grafting.