超声微泡靶向介导转染微小核糖核酸-21防治冠状动脉微栓塞致心肌损伤机制的研究

Coronary microembolization (CME) is an intractable complication within the therpy of acute coronary syndrome( such as percutaneous coronary intervention and coronary artery bypass surgery). As demonstrated in the previous studies of ours and abroad, inflammation and apoptosis after CME are responsible for the myocardial damage.Some recent studies reported that miRNA-21 had a protective effect on myocardium. The cardiac protective effect may be associated with the anti-apoptotic and anti-inflammatory process through regulating the signal transduction pathways, which were mediated by target genes of miRNA-21, such as PDCD4, PTEN, and SPRY1/2. However, the exactly protective mechanism is unclear. In our preliminary experiment,we found that the expression of PDCD4, PTEN, and SPRY1/2 genes increased significantly after CME.So the signal transduction pathways mediated by PDCD4, PTEN, and SPRY1/2 may play important roles in myocardial dysfunction resulting from CME. In the present study, we will establish animal model of CME in mini-swine by using intervention method.After constructing the eukaryotic expression plasmid of miRNA-21, we deliver miRNA-21 to impaired myocardium through Ultrasound-targeted microbubble destruction (UTMD). Then, We detect the signal transduction pathways mediated by PDCD4, PTEN, and SPRY1/2 respectively to clarify the mechanism of miRNA-21 in treatment of myocardial dysfunction resulting from CME deeply.

冠状动脉微栓塞（Coronary Microembolization，CME）是冠心病介入治疗中棘手的并发症。我们及国外的前期研究表明：CME后发生的炎症和凋亡是引起心肌损伤的主要原因。新近研究证明微小核糖核酸-21（miRNA-21）对心肌有保护作用，可能是通过调控PDCD4、PTEN、SPRY1/2等靶基因介导的信号转导通路发挥抗凋亡和抗炎作用起效，但具体机制尚不清楚。我们在预实验中发现CME后，PDCD4、PTEN、SPRY1/2等靶基因表达明显升高，它们介导的信号转导通路很有可能参与了CME致心肌损伤。本项目拟经导管建立CME猪的动物模型，构建miRNA-21真核表达质粒，通过超声微泡靶向介导转染miRNA-21,检测CME后miRNA-21靶基因（PDCD4、PTEN、SPRY1/2）介导的信号转导通路的激活情况，以深入阐明miRNA-21防治CME致心肌损伤的效应机制。

冠状动脉微栓塞（Coronary Microembolization，CME）是冠心病介入治疗中棘手的并发症，我们及国外的前期研究表明：CME 后发生的炎症和凋亡是引起心肌损伤的主要原因。有研究证明微小核糖核酸-21（miRNA-21）对心肌有保护作用，可能是通过调控PDCD4、PTEN、SPRY1/2等靶基因介导的信号转导通路发挥抗凋亡和抗炎作用起效，但具体机制不清楚。本研究项目成功经导管建立CME 猪的动物模型，首先，我们通过荧光定量PCR、Western Blot、HE、HEFP等证明了PDCD4/PTEN参与了CME致心功能的损伤，并呈现出明显的时间变化规律,但 SPRY1/2基因的差异不明显。然后，我们通过siRNA技术沉默PDCD4基因，证明PDCD4/NF-kB/TNF-a信号转导通路激活是CME致心肌炎症、损伤的重要机制，同时通过沉默PTEN基因,证明PTEN/P13K/AKT/Bad是CME致心肌细胞凋亡的重要机制。最后，构建miRNA-21 真核表达质粒，通过超声微泡靶向技术，成功转染microRNA-21至心肌组织，发现可以有效抑制PDCD4/NF-kB/TNF-a信号转导通路，减少心肌炎症反应，减少了CME致心肌损伤。我们的研究成果为临床开发microRNA-21药物治疗和预防CME致心肌损伤提供了重要的理论依据。