Human umbilical cord mesenchymal stem cell‐derived exosomes (hucMSC‐exosomes) have been implicated as a novel therapeutic approach for tissue injury repair and regeneration, but the effects of hucMSC‐exosomes on coxsackievirus B3 (CVB3)‐induced myocarditis remain unknown. The object of the present study is to investigate whether hucMSC‐exosomes have therapeutic effects on CVB3‐induced myocarditis (VMC). HucMSC‐exosomes were identified using nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and Western blot. The purified hucMSC‐exosomes tagged with PKH26 were tail intravenously injected into VMC model mice in vivo and used to administrate CVB3‐infected human cardiomyocytes (HCMs) in vitro, respectively. The effects of hucMSC‐exosomes on myocardial pathology injury, proinflammatory cytokines and cardiac function were evaluated through haematoxylin and eosin (H&E) staining, quantitative polymerase chain reaction (qPCR) and Doppler echocardiography. The anti‐apoptosis role and potential mechanism of hucMSC‐exosomes were explored using TUNEL staining, flow cytometry, immunohistochemistry, Ad‐mRFP‐GFP‐LC3 transduction and Western blot. In vivo results showed that hucMSC‐exosomes (50 μg iv) significantly alleviated myocardium injury, shrank the production of proinflammatory cytokines and improved cardiac function. Moreover, in vitro data showed that hucMSC‐exosomes (50 μg/mL) inhibited the apoptosis of CVB3‐infected HCM through increasing pAMPK/AMPK ratio and up‐regulating autophagy proteins LC3II/I, BECLIN‐1 and anti‐apoptosis protein BCL‐2 as well as decreasing pmTOR/mTOR ratio, promoting the degradation of autophagy flux protein P62 and down‐regulating apoptosis protein BAX. In conclusion, hucMSC‐exosomes could alleviate CVB3‐induced myocarditis via activating AMPK/mTOR‐mediated autophagy flux pathway to attenuate cardiomyocyte apoptosis, which will be benefit for MSC‐exosome therapy of myocarditis in the future.

中文翻译：

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脐带间充质干细胞衍生的外来体通过激活AMPK / mTOR介导的自噬通量途径来减轻病毒性心肌炎。

人脐带间充质干细胞来源的外泌体（hucMSC-外泌体）被认为是一种新的组织损伤修复和再生治疗方法，但是hucMSC-外泌体对柯萨奇病毒B3（CVB3）诱导的心肌炎的影响仍然未知。本研究的目的是研究hucMSC外泌体是否对CVB3诱导的心肌炎（VMC）有治疗作用。通过纳米粒子跟踪分析（NTA），透射电子显微镜（TEM）和Western印迹鉴定了HucMSC外泌体。将标记有PKH26的纯化的hucMSC外泌体体内尾部静脉注射，并分别用于体外施用受CVB3感染的人心肌细胞（HCM）。hucMSC外泌体对心肌病理损伤的影响 通过苏木精和曙红（H＆E）染色，定量聚合酶链反应（qPCR）和多普勒超声心动图评估促炎细胞因子和心脏功能。使用TUNEL染色，流式细胞仪，免疫组织化学，Ad-mRFP-GFP-LC3转导和Western印迹探索了hucMSC外泌体的抗凋亡作用和潜在机制。体内结果显示hucMSC外泌体（50μgiv）可显着减轻心肌损伤，减少促炎细胞因子的产生并改善心脏功能。此外，体外数据显示hucMSC外泌体（50μg/ mL）通过增加pAMPK / AMPK比并上调自噬蛋白LC3II / I，BECLIN-1和抗凋亡蛋白BCL-来抑制受CVB3感染的HCM的凋亡。 2，同时降低pmTOR / mTOR比，促进自噬通量蛋白P62的降解并下调凋亡蛋白BAX。总之，hucMSC外泌体可通过激活AMPK / mTOR介导的自噬通量通路来减轻心肌细胞凋亡，从而减轻CVB3诱导的心肌炎，这将为将来的MSC外泌体治疗心肌炎带来益处。