| Background:Distraction osteogenesis(DO)technology refers to stretch gradually two bone segments separated from each other,through a specific traction device,in order to get the new bone formed.Since Codivilla's research that distraction osteogenesis technique could be used to extend limb long bone,more and more patients with limb deformities,bone defect were corrected by this technology.Despite the advantages,for example,high quality,no need for the autologous bone grafts and easy to operate,there still exists some disadvantages.For instance,the limited distraction speed,long treatment cycle and the mal-formation of new bone,like bone nonunion or fiber healing due to the too fast or too long traction.How to improve the efficiency of the distraction osteogenesis and decrease the time of traction is becoming the focus among many scholars.Recent research suggests that the Wnt/?-catenin signal pathway plays a role in the bone reaction to the distraction stimulation.Wnt/?-catenin signal pathway may accelerate new bone formation via influencing related protein expression in the process of distraction osteogenesis.Objective:Through testing the expression of ?-catenin on rabbit mandibular distraction osteogenesis,applying the rabbit model of bilateral mandibular distraction osteogenesis to explore the role of ?-catenin in distraction osteogenesis of new bone formation.Methods:26New-Zealand rabbits were employed.They were randomly divided into normal control group(group A)and the fracture control group(group B)and distraction group(group C).The normal control group two rabbits were without surgery.The rabbits,under general anaesthesia,of group B and group C were given bilateral mandibles osteotomy at the rear side.The group B were immediately fixed with titanium plates after the 5mm bone cutting.The mandibular segments of group C were fixed with special distractors for rabbits.After 3 days,the distraction started at a rate of 0.8mm/d and this period lasted for 7 days.The rabbits of group B and group C were respectively killed at 6,10,17,24,31,38 days after operation.The bilateral mandibles were observed under X-ray examination for bone healing,and Western Blot and Immunohistochemistry methods were used to detect the distribution and expression of ?-catenin.The experimental data were analyzed according to theexperimental design.The samples of normal group were killed and involved in the same bilateral mandibles detection experiment.Results:All experiment animals underwent well operation and survived,the distraction devices function well and when the distraction ended,the rabbits'lower jaws were obviously forward and the occlusions were in disorder.The testing results of the Western blot showed that the expression of P-catenin gradually increased at distraction period.In the final stage of distraction period,the expression of ?-catenin reached the peak.However,the expression of ?-catenin progressively decreased in the consolidation period.Meanwhile,?-catenin expression in distraction group was higher than that of fracture control group.Immunohistochemistry stain showed that the expression of P-catenin gradually increased and reached the highest at 6,10 days after surgery.Both cytoplasm and cell nucleus were positive.With the disappearance of the distraction stress,the expression of ?-catenin progressively decreased at 17 days after surgery but still positive.?-catenin mainly located in the cell nucleus.By comparison,?-catenin expression in distraction group was significantly higher than that of fracture control group.(r>0.75,p<0.05).Conclusion:The high expression level of ?-catenin during the process of distraction osteogenesis suggests that ?-catenin participates in the regulation of distraction osteogenesis of new bone formation. |
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