| Part one:CT-based comparision of defect length and locality in a rabbit radial defect modelObjective To investigate the radial critical size defect model and find the appropriate defect length and locality with CT imaging analysis.Methods Twenty-four 6-month-old healthy male New Zealand White rabbits were included in this study. Among these rabbits,18 were divided into 1.0-cm group (group A),1.5-cm group (group B),2.0-cm group (group C) according to the defect length. For each rabbit, both sides of the radius were operated and there were 6 rabbits with a total of 12 sides in each group. CT scans were taken immediately after surgery, and at 4-week intervals. The bone defect healing was evaluated with Hedberg scores from CT 3D-reconstruction. The rabbits were sacrificed 12 weeks postoperatively and the forearms were harvested for histological analysis to evaluate the new bone formation. Based on the results of Group A, B, C, we selected the best defect length, and performed the surgery in group D (6 rabbits) at the proximal side of the radius. The defect center was selected 3.0cm distal from the olecroanon. The bone healing and postoperative complications were compared between the four groups.Results Two rabbits were euthanized and replenished due to severe infection postoperatively. Four weeks postoperatively, unilateral ulnar fracture was observed in two rabbits in group D. Therefore, the two sides were not included in the analysis. Twelve weeks postoperatively, all rabbits were euthanized for analysis of the gross anatomy.11 sides (91.7%) of radius in group A had been observed bridged completly, and the surface was smooth. There were only three sides bridged completely in Group B and D. However, none defects in group C were observed with bridged callus. With the closure of both ends, the defect area was filled with fibrous tissue. The histological analysis showed that the bone defect in group A had been repaired perfectly,and the bone marrow cavity was recanalization.However,the other three groups showed the ends of defect were closed and the defect area was filled with fibrous tissue; In group A, intramedullary canals in bridged radius were observed from CT 3D-reconstrucion images. There was small amount of callus appeared at both broken ends and the ulnar sides in the no-bridged radius. Hedberg scores comparsion showed significant difference between group B (1.75±1.06) and group A (3.83± 0.39) (P<0.05). However, no significant difference was observed among group B, group C (1.33±0.65) and group D (1.60±0.70) (P> 0.05).Conclusions In rabbit radial defect model,1.5 cm was considerd to be the most appropriate length in 6-month-old male New Zealand White rabbits. Both the middle and the proximal side of the radius can be applid in this model.Part two:Study on treatment of rabbit radial CSD model with SF/PLCL scaffold composited with BMSCsObjective To study the osteogenic potential of SF/PLCL electrospinning material composited with rabbit BMSCs in repairing the rabbit radial CSD model.Method 3 three-month-old male New Zealand white rabbits were taken marrow, then put the osteogenic induced rabbit BMSCs into BMSCs/Alginate hydrogel to reserve; 8 six-month-old male New Zealand white rabbits were divided into A, B groups. For each rabbit CSD model, both sides of the radius were operated.The experimental group (group A):SF/PLCL material composited with rabbit BMSCs/ alginate hydrogel was implanted into bone defect; the control group (group B), bilateral surgery of radial CSD.12 weeks postoperatively, X-ray and CT scan three-dimensional reconstruction were used to evaluate the new bone formation; All rabbits were sacrificed after imaging, and gross specimens were observed by HE staining to evaluate bone repair situation.Results 12 weeks postoperatively,general observation:Group A, casing material was degraded partly, bone tissue from the ends of bone defects grew along the casing stump material, but unfinished bridge bone defects; Group B, the defect area was filling with soft tissue, the ends of bone defects were closed. X-ray and CT scan three-dimensional reconstruction showed:group A. bone tissue from the ends of bone defects grew along the casing stump material, but unfinished bridge bone defects;but only a small amount of bone defects were partly connected; Group B, the ends of bone defects were closed, no bridging. Histology results:group A, casing material was degraded partly, the new bone cell was on the casing material sidewall, fibroblast ingrowth internal material, the defects were unrepaired; Group B, the defect area was filling with soft tissue,the ends of bone defects were closed.Conclusion 1.5cm radial bone defects in 6-month-old male New Zealand white rabbits can be used to build rabbit CSD animal models; electrospinning SF/PLCL casing material has good biocompatibility,but its osteogenic ability and degradation should to be further improved. |
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