The expression of β-catenin in callus of distraction gap during mandibular distraction osteogenesis in rabbits / 中华整形外科杂志

ABSTRACT

Objective@#To explore the role of β-catenin in distraction osteogenesis of new bone formation, the expression of β-catenin in the distraction gap callus was detected during rabbit mandibular distraction osteogenesis.@*Methods@#26 New-Zealand rabbits were randomly divided into 3 groups. Group A is a normal control group with 2 rabbits, group B is the mandibular defect control group, and group C is the distraction group. Group B and C with 12 rabbits, respectively. The two rabbits in group A without surgery, their mandibles are normal control. In group B, vertical osteotomy was performed between the first molar and the mental foramen on the mandibles bilaterally, followed by rigid internal fixation with titanium plates and screw with 5 mm gap immediately. In group C, after the same osteotomy was performed, the fragments of mandibles were reduced and fixed with mandibular distractors bilaterally. On the fourth day postoperatively, the distraction started at a rate of 0.8 mm/d and lasted for 7 days, followed by consolidation period. Two rabbits of group B and C were sacrificed at 6th, 10th, 17th, 24th, 31st, 38th day postoperatively, respectively. The newly formed callus in the distraction gap of mandibles was harvested for Western blotting and immunohistochemistry examination to detect the distribution and expression of β-catenin. The experimental data were analyzed by SPSS 22.0 statistical software using Spearman function.@*Results@#The result of Western blotting showed that the expression of β-catenin gradually increased at distraction period(6-10 days after surgery) and reached the peak at the end of the distraction period(10th day postoperatively), it gradually decreased during the consolidation period. However, the expression of β-catenin in group C was higher than that of group B. Immunohistochemistry stain showed that the expression of β-catenin mainly located in inflammatory cells(eg. monocyte), fibroblast of the granulation tissue, the osteoblasts, osteocyte on the surface of new formed trabecular, and the connective tissues surrounding the new bone in the new formed callus. Cytoplasmic and nuclear staining were positive. In group C, the expression of β-catenin was strong (3.245 8±0.132 3) after distraction (6th day postoperatively), and reached a peak (4.602 8±0.021 9) on the 10th day postoperatively. With the disappearance of the distraction stress, the expression of β-catenin gradually decreased since17th day postoperatively(3.639 8±0.125 5), but the staining was still positive. In group B, the strong positive staining of β-catenin on the 6th day after surgery (2.734 0±0.134 7), the strongest staining on the 10th day after surgery (3.101 3±0.104 8), and the expression of β-catenin on the 17th day after surgery (2.542 8±0.211 1) was weaker than that on the 10th day after surgery. At each time point, the expression of β-catenin in group C was significantly higher than that in group B, and the difference was statistically significant (r=0.943, P=0.005 6).@*Conclusions@#During mandibular distraction osteogenesis, the distraction stress activates the Wnt signal pathway to enhance the expression of β-catenin, it suggests that β-catenin plays an important role in the transformation of the mechanical signal to chemical signals during the process of distraction osteogenesis, and participates in the regulation of new bone formation during distraction osteogenesis.