新生SD大鼠心脏损伤后修复与miR-223-3p表达的关系

Role of miR-223-3p in cardiac repair after injury in neonatal SD rats

目的探索新生SD大鼠心脏损伤后心肌能否再生,筛选与修复方式相关的miRNA。方法用出生1～2 d的SD大鼠50只造心脏损伤模型,随机分至假手术组(Sham,简称"S")和模型组(Model,简称"M"组),S组打开胸腔暴露心脏后缝合关闭;M组剪取心尖组织少许,余同S组。每组造模成功20只(各取2只作为术后0 d基线对照);术后7 d、14 d每组3只行心脏HE、Masson染色,观察形态学改变。每组术后7 d、14 d、21 d取4只心脏,RT-qPCR检测3个时间点心脏miRNAs的表达较术后0 d增高的倍数作为相对表达量,比较不同时间组间表达差异有无统计学意义。结果术后7 d HE、Masson染色M组心脏损伤后心肌细胞变性坏死、胶原沉积显著;14 d时瘢痕、心肌纤维化形成,修复基本完成。10种miRNAs相对表达量升高,术后7 d,与S组相比,miR-223-3p相对表达量更高,差异有统计学意义(404.28±302.73 vs6.17±4.61,P=0.021),其余miRNAs表达量差异无统计学意义;术后14 d、21 d所有miRNAs表达组间差异均无统计学意义;修复过程中miR-223-3p表达在术后7 d升高至404.28倍,14 d时降为11.85倍,可能与病理修复过程密切相关。结论新生乳鼠心肌损伤不能完全再生,以纤维化修复为主;miR-223-3p表达特异性升高,可能是心脏损伤后纤维性修复的重要调控基因。

Objective To explore whether the myocardium of newborn SD rats can regenerate after cardiac injury, and screen miRNAs associated with heart repair. Methods A model of cardiac injury was established in 1-and 2-day-old neonatal SD rats. Fifty rats were divided into two groups, sham group with the chest wall opened and the incision sutured immediately after heart exposure and model group with a little cut-off of the apical tissue, and the rest procedures were the same as the sham group. The model was successfully established in 40 rats with 20 samples in each group and 2 samples were taken as the postoperative 0 day baseline control. Three rats of each group were sacri?ced and their hearts were taken and stained with HE and Masson at 7 days and 14 days after operation to observe morphological changes. Four rats of each group were sacri?ced and their hearts were taken and expression levels of miRNAs were detected by RT-qPCR at 7 days, 14 days and 21 days after operation. The fold changes of miRNAs at these three time points to those at postoperative 0 day were taken as the relative expression levels. And the expression differences were analyzed between groups at different time points. Results In the model group, at 7 days after operation, cardiomyocyte degeneration,necrosis and collagen deposition among cardiomyocytes were observed in HE and Masson staining respectively;Scar and myocardial?brosis had been formed at 14 days. The relative expression of selected 10 miRNAs increased at 7 days after operation, and compared to the sham group, the relative expression of miR-223-3 p was signi?cantly higher in model group(404.28±302.73 vs 6.17±4.61,P=0.021). The rest miRNAs showed no significant difference between two groups. At 14 days and 21 days after operation, the relative expression levels of all miRNAs showed no signi?cant difference between two groups. During the repair process, miR-223-3 p expression dramatically increased to 404.28 times at 7 days after operation and sharply decreased to 11.85 times at postoperative14 days, which suggested that the change might be closely related to the pathological repair process. Conclusion The myocardium in neonatal rats can not be completely regenerated after heart injury, and it is mainly repaired by scar and myo?briosis. The increased miR-223-3 p expression indicates that it may be an important regulatory gene for ?brous repair after cardiac injury.