Pathological observation on the repair of bone defect of spinal tuberculosis in rabbits with HRZ/PLGA coated autogenous iliac bone

English Keywords:Spinal tuberculosis  Sustained anti-tuberculosis drugs  Autogenous iliac bone  Bone repair  Pathological

English Abstract:

  【Abstract】 Objectives: To observe the pathological characteristics of bone defect of spinal tuberculosis in rabbits with autologous iliac bone coated with sustained-release anti-TB drug HRZ/PLGA and the toxicity to peripheral organs. Methods： 60 New Zealand rabbits of spinal tuberculosis models were randomly divided into 3 groups, 20 in each group, all underwent radical debridement. Group A(experimental group) was implanted with autologous iliac bone coated with sustained-release anti-TB drug HRZ/PLGA(isoniazid, rifampicin, pioglitazone/acetyl acetic acid); group B(control group) was implanted with autologous iliac bone with blank coating; group C(blank control group) was implanted with autogenous iliac bone. 5 rabbits were randomly selected at 2, 4, 8 and 16 weeks after operation and observed the tissues of bone graft by visual and microscopic view, the healing of implant interface and the degradation of bone graft material were studied by histopathological observation. The pathological specimens of heart, liver, spleen and kidney of group A at 2 weeks and 4 weeks after operation were made to specimen slices to observe the toxicity of peripheral organs. The imaging examinations(X-ray, CT, MRI) were performed at 2, 4, 8 and 16 weeks in experimental group after operation, and the fusion of bone graft was observed. Results: Visual observation in group A found that, at 16 weeks after operation, the bone defect was replaced by dense and regular bone tissue, the hardness was similar to the surrounding bone tissue, and the bone defect had reached the standard of bone healing, the degradation and integration of bone graft materials had been basically completed. In group B and group C, at 16 weeks after operation, some rabbits were observed formation of light-yellow purulent material, and scar hyperplasia was observed in bone defect and pathological bone bridge, paravertebral worm erosion damage and defect osteoid bridge could be seen. Microscopic observation in group A found that, at 16 weeks after operation, the production of lamellar bone and trabecular bone increased, the proliferation of bone cell was active, shape of bone cell and structure of trabecular bone were nearly mature, no inflammatory cells and necrotic materials formation. In group B and group C, at 16 weeks after operation, there were more irregular osteoblast and slender trabecular bone, inflammatory cell aggregation between trabecular bones, and necrotic material formed in some area. Imaging features of the bone graft healing of rabbits in group A were observed, and at the end of 16 weeks, the bone-material interface combined closely, bone graft healed good. At 8 weeks and 16 weeks after operation, the bone-material interface was made into pathological slice to quantitative analysis on the area of bone trabecular, and the bone trabecular area in group A was significantly higher than that in group B and group C(P＜0.05). In group A, no abscess, bone destruction, sequestrum, or caseous necrosis was observed at each time of observation, the healing of bone-material interface in group A was better than that in group B and group C(P<0.05). The heart, liver, spleen and kidney tissues of group A were observed at 2 weeks and 4 weeks after operation, no sign of peripheral organ damage was observed. Conclusions: The autologous iliac bone coated with sustained-release anti-TB drug HRZ/PLGA which was planted into the bone defect after debridement could promote the repair of bone defect and the healing of the lesion, no peripheral organ damage was observed. It has been proved to be a good sustained anti-tuberculosis material.