低强度聚焦超声促进SD大鼠慢性骨骼肌损伤修复

Low intensity focused ultrasound promotes the repair of chronic skeletal muscle injury in sprague-dawley rats

目的:探讨低强度聚焦超声(low intensity focused ultrasound,LIFU)对大鼠慢性骨骼肌损伤的修复作用。方法:用重力打击器构建大鼠慢性骨骼肌损伤模型,构建成功后模型分为超声组和对照组,超声组采用LIFU每天1次,连续辐照患处14 d,对照组假治疗。2组分别于治疗第3、10、21天取损伤区域组织,采用苏木精-伊红(hematoxylin and eosin,HE)染色法观察组织变化,免疫组化定量生肌决定因子(Myf-5)和辅肌动蛋白(α-actinin)表达强度并使用图像分析软件进行平均光密度(average optical density,AOD)分析,实时荧光定量多聚酶链反应(real-time quantitative polymerase chain reaction,qRT-PCR)分析肌分化因子(MyoD)m RNA表达水平,对组织修复情况进行评价。结果:HE染色图片提示超声组坏死肌纤维逐渐被新生排列整齐肌纤维取代;对照组纤维组织形成,炎症细胞浸润,肌纤维萎缩明显。治疗开始的第3、10、21天,超声组α-actinin(3 d=0.270±0.026,t=2.963,P=0.018;10 d=0.244±0.011,t=2.865,P=0.027;21 d=0.222±0.031,t=1.073,P=0.317)、Myf-5(3 d=0.291±0.050,t=2.691,P=0.027;10 d=0.246±0.015,t=2.726,P=0.032;21 d=0.166±0.021,t=0.369,P=0.722)、MyoD mRNA(3 d=5.613±0.379,t=4.679,P=0.002;10 d=3.276±0.261,t=2.377,P=0.048;21 d=1.810±0.200,t=0.634,P=0.546)的表达均高于对照组α-actinin(3 d=0.234±0.008;10 d=0.214±0.020;21 d=0.203±0.023)、Myf-5(3 d=0.225±0.023;10 d=0.211±0.025;21 d=0.161±0.016)、MyoD mRNA(3 d=4.465±0.397;10 d=2.807±0.356;21 d=1.712±0.280),且在第3、10天差异有统计学意义(P<0.05)。结论:LIFU能促进大鼠慢性骨骼肌损伤再生修复,改善组织结构。

Objective:To investigate the effect of low intensity focused ultrasound(LIFU)on the repair of chronic skeletal muscle injury in rats.Methods:An impactor was used to establish a rat model of chronic skeletal muscle injury,and then the rats were divided into ultrasound group and control group.The rats in the ultrasound group were given LIFU once a day for 14 consecutive days,and those in the control group were given sham treatment.Tissue samples of the injured area were collected on days 3,10,and 21 of treatment,and HE staining was used to observe histological changes.Immunohistochemistry was used to measure the expression of Myf-5 andα-actinin;image analysis software was used to measure average optical density(AOD);real-time quantitative polymerase chain reaction was used to measure the mRNA expression of MyoD.Tissue repair was also evaluated.Results:HE staining showed that necrotic muscle fibers were gradually replaced by newly formed muscle fibers in ordered arrangement in the ultrasound group,while the formation of fibrous tissue,inflammatory cell infiltration,and marked muscle fiber atrophy were seen in the control group.Compared with the control group on days 3,10,and 21 of treatment,the ultrasound group had higher expression ofα-actinin(0.270±0.026/0.244±0.011/0.222±0.031 vs.0.234±0.008/0.214±0.020/0.203±0.023,t=2.963,2.865,and 1.073,P=0.018,0.027,and 0.317)and Myf-5(0.291±0.050/0.246±0.015/0.166±0.021 vs.0.225±0.023/0.211±0.025/0.161±0.016,t=2.691,2.726,and 0.369,P=0.027,0.032,and 0.722)and higher mRNA expression of MyoD(5.613±0.379/3.276±0.261/1.810±0.200 vs.4.465±0.397/2.807±0.356/1.712±0.280,t=4.679,2.377,and 0.634,P=0.002,0.048,and 0.546),with statistical significance on days 3 and 10(P<0.05).Conclusion:LIFU can promote the regeneration and repair of chronic skeletal muscle injury in rats.