基因治疗对兔下颌骨牵引过程中骨形成蛋白-2表达的影响

Effect of gene therapy on the expression of bone morphogenetic protein-2 during mandible distraction

目的探索电穿孔介导的基因治疗对兔下颌骨牵引成骨过程中骨形成蛋白-2（bone morphogenetic protein-2．BMP2）表达的影响。方法新西兰大白兔双侧下颌骨截骨，术后3d开始牵引，连续牵引7d后，将实验动物分为A、B、C、D、E5组，A、B、C组分别在牵引区注射2μg（0．1μg／μ1）重组质粒pIRES-hVEGF165-hBMP2、pIRES-hBMP2、pIRES-hVEGF165。D组与E组分别注射相同剂量的空质粒（pIRES）和生理盐水（NS）。各组分别于固定期第7、14、28天处死动物，取材行免疫组织化学检测BMP2的表达情况，并利用病理图像分析系统进行分析。结果BMP2主要在肉芽组织中的炎细胞及新生幼稚骨小梁表面的细胞组织中表达。固定7d时表达最强烈，各时点基因治疗组明显强于对照组。结论电脉冲介导的基因治疗能使BMP2在牵引区的表达增强和表达时限延长并促进细胞的分裂增殖与分化，促进牵引区细胞基质的形成和新骨生成。

Objective To investigate the expression patterns of major bone growth factors and bone morphogenetic protein-2 （BMP2） in the distracted calluses following transfected gene during mandibular distraction osteogenesis in a rabbit model. Methods Bilateral mandibular osteotomies were performed in New-Zeland rabbits. After a latency of 3 days, the mandibles were elongated using dis- tractors for 7 days. After the completion of distraction, the rabbits were randomly divided into 5 groups. Three animals each were sacrificed at the end of the delay phase, at 7. 14, and 28 days after completion of distraction, respectively. The lengthened mandibles were harvested and processed for immunohistochemical detection of BMP2 expression, the mean optic densities and integral optical den- sity of BMP2 positive cells were measured by computerized image analyzer. Results Elevated cellular expression of BMP2, in the distraction gap, was observed following mandibular distraction. BMP2 staining was mainly located in inflammatory cells, and the connective tissues arrounding the new bone. Their strongest expression was the 7th day, some of those growth factors expressed weakly or nega- tively. Conclusions Electroporation-mediated gene transfection can promote BMP2 expression effec- tively, which plays an important role in cell differentiation and proliferation during distraction osteo- genesis. The BMP2 stimulates extracellular matrix synthesis, induces the proliferation and differentia- tion of fibroblasts and osteoblasts, which then promotes the new bone formation and repair.