力学环境对骨折早期骨折端间充质干细胞募集的影响

Effect of mechanical environment on recruitment of mesenchymal stem cells at fracture site during early stage of fracture healing

目的探究骨折早期力学环境对骨折端间充质干细胞(MSC)募集的影响。方法建立大鼠股骨骨折模型,以不同刚度系数的外固定架予以固定,分为对照组(超高刚度外固定架组)、高刚度外固定架组和低刚度外固定架组。术后当天和2周摄X线片,观察骨痂及骨折愈合情况。术后2、4、6、10 d取骨折端组织,分离有核细胞,流式细胞术检测CD29+CD90+细胞占有核细胞比例。计算骨折端MSC绝对数量。结果 X线检查显示,术后2周高刚度外固定架组骨痂量明显少于低刚度外固定架组。术后2、4、6、10 d各组CD29+CD90+细胞数量逐渐减少(P<0.05);术后2、4、6、10 d低刚度外固定架组CD29+CD90+细胞数量大于高刚度外固定架组(P<0.05),且低、高刚度外固定架组CD29+CD90+细胞数量均大于对照组(P<0.05)。结论力学环境会影响骨折区MSC募集,微动可促进骨折愈合。

Objective To explore the influence of mechanical environment on recruitment of mesenchymal stem cells(MSCs)at fracture site during early stage of fracture healing.Methods The rat femur fracture models were established,and fixed with external fixator of different stiffness coefficient.They were divided into control group with super-high stiffness external fixation,high stiffness fixator group and low stiffness fixator group.The bone callus and the degree of fracture healing were observed by X-ray after two weeks.The tissues of fracture site were obtained at 2,4,6,10 days after surgery.The nucleated cells were isolated,and the ratio of CD29+CD90+ cells was detected by flow cytometry.Results According to the X-ray results,the amount of callus of high stiffness fixator group was significantly less than that of low stiffness fixator group.The ratio of CD29+CD90+cells of three groups decreased with the increasing of healing time(P<0.05).The ratio of CD29+CD90+ cells of low stiffness fixator group was higher than that of high stiffness fixator group,while that of control group was lowest level(P<0.05).Conclusion The recruitment of MSCs at fracture site could be affected by the mechanical environment,and subtle movement could promote fracture healing.