髓内固定治疗长骨干骨不连的分子机制研究

Molecular biological mechanism of intramedullary fixation for long bone nonunion: an experimental study in rabbit

[目的]利用髓内固定治疗桡骨骨不连的家兔动物模型,探讨髓内固定治疗长骨干骨不连的分子生物学机制。[方法]选取30只新西兰大白兔,采用计算机产生随机数字的方法,对兔子进行随机编号并分为实验组(n=15)和对照组(n=15)。两组兔子均在无菌条件下施术,建立右桡骨骨不连模型。造模成功后,两组兔子均予骨不连区断端新鲜化,实验组实施克氏针髓内固定术,对照组不予干预。分别于右桡骨骨不连术后第2、4、8周,从两组兔子中分别随机选取5只,取右侧骨不连区组织,采用免疫组化法观察组织中骨形态发生蛋白-2(BMP-2)和血管内皮生长因子(VEGF)的表达情况,并进行对比分析。[结果]右桡骨骨不连术后第2、4周,两组光镜下均可见棕黄色阳性细胞表达。实验组BMP-2和VEGF表达的阳性细胞均多于对照组,实验组对应的平均光密度值(MOD值)与对照组差异均有统计学意义(P<0.05)。术后第8周,肉眼可见两组BMP-2表达的阳性细胞数均较前4周增加,实验组表达多于对照组,两组MOD值差异有统计学意义(P<0.05);对照组VEGF表达的阳性细胞数继续较前4周增加,对照组阳性细胞表达多于实验组,两组的MOD值差异有统计学意义(P<0.05)。[结论]髓内固定治疗长骨干骨不连可能通过调控BMP-2和VEGF的表达来实现断端愈合。

[Objective] To explore the molecular biological mechanism of intramedullary fixation for long bone nonunion in the rabbit. [Methods] In this experimental study, 30 New Zealand white rabbits were divided into the experimental group and the control group with 15 animals in each group according to random numbers generated by a computer. The nonunion models of right radius in the two groups were established under the aseptic condition. After success of the models created, the bone ends of the nonunion areas in the two groups were refreshed, then the bone ends in the experimental group were intramedullary fixated by Kirschner wires, while those in the control groups left untreated. At 2, 4 and 8 weeks after operation, tissues of the nonunion areas were respectively harvested from five rabbits in each group to detect the expressions of bone morphogenetic protein-2（BMP-2） and vascular endothelial growth factor（VEGF） by immunohistochemical assay. [Results] At 2, 4 weeks after operation,positive brown cells were visible under light microscope, and the number of positive cells labeled for BMP-2 and VEGF in the experimental group were greater than those in the control group. In addition, the experimental group got statistically significantly higher mean optical density（MOD） value of quantitative immunohistochemical assay regarding to BMP-2 and VEGF than the control group（P〈0.05）. At 8 weeks, the numbers of positive cells of BMP-2 in both groups increased compared with those at 4 weeks, in which the experimental group was also superior to the control group, associated with a statistically significant difference in MOD value between the two groups（P〈0.05）. However, although the number of positive cells of VEGF in the control group continuously increased at 8 weeks, the number in the experimental groups kept unchanged compared to that at 4 weeks,the former was superior to the latter associated with a statistically significant difference in the MOD value between the two groups（P〈0.05）. [Conclusion] The intramedullary fixation for long bone nonunion might be related to regulating the expressions of BMP-2 and VEGF.