To explore the impact and mechanism of human mesenchymal stem cells (hMSCs) on the angiogenesis of cardiac microvascular endothelial cells (CMECs) after ischemia insult. Exosomes derived from hMSCs (hMSCs-Exo) were identified by Western blotting and labeled by PHK-67. CMECs were isolated from rat myocardial tissues. After hypoxic treatment, CMECs were cultured with hMSCs and exosome inhibitor (GW4869) or transfected with si-COL4A1 + miR-543 inhibitor. CMEC proliferation, migration, invasion, and angiogenesis were examined. Target genes of miR-543 were predicted and then were identified by dual luciferase assay. Myocardial infarction (MI) rat model established by suture occlusion was intravenously injected with hMSCs-Exo. Fluorescence microscope was applied to visualize exosomes in myocardial tissues. Infarction volume and pathologies of myocardial tissues were observed. Ki-67 and miR-543 expressions were detected. The isolated hMSC-Exo expressed TSG101, HSP70, and CD63. Hypoxia-treated CMECs cultured with hMSCs exhibited high proliferation, migration, invasion, and angiogenesis ability, while incubation with exosome inhibitor GW4969 offset the promoting effects of hMSCs on the proliferation, migration, invasion, and angiogenesis of CMECs. hMSCs transfected with miR-543 inhibitor brought CMECs weak viability and angiogenesis ability. CMECs transfected with si-COL4A1 and miR-543 inhibitor showed low proliferation, migration, invasion, and angiogenesis compared to those transfected with si-COL4A1 alone. hMSCs-Exo entered the myocardial tissues of MI rats. Injection of hMSCs-Exo in MI rats diminished infarction size, attenuated MI-induced injuries, and increased Ki-67 expression. hMSCs-Exo facilitates the proliferation, migration, invasion, and angiogenesis of CMECs through transferring miR-543 and downregulating COL4A1 expression.

中文翻译：

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人间充质干细胞衍生外泌体中的 miR-543 通过 COL4A1 促进心肌梗死后心脏微血管内皮细胞血管生成

探讨人间充质干细胞（hMSCs）对缺血损伤后心脏微血管内皮细胞（CMECs）血管生成的影响及机制。通过蛋白质印迹鉴定源自 hMSCs (hMSCs-Exo) 的外泌体并用 PHK-67 标记。从大鼠心肌组织中分离出CMEC。缺氧处理后，CMECs 与 hMSCs 和外泌体抑制剂 (GW4869) 一起培养或用 si-COL4A1 + miR-543 抑制剂转染。检查CMEC增殖、迁移、侵袭和血管生成。预测miR-543的靶基因，然后通过双荧光素酶测定法鉴定。用hMSCs-Exo静脉注射缝合封闭建立的心肌梗死（MI）大鼠模型。应用荧光显微镜观察心肌组织中的外泌体。观察心肌组织的梗死体积和病理。检测到 Ki-67 和 miR-543 的表达。分离的 hMSC-Exo 表达 TSG101、HSP70 和 CD63。与hMSCs一起培养的缺氧处理的CMECs表现出较高的增殖、迁移、侵袭和血管生成能力，而与外泌体抑制剂GW4969孵育抵消了hMSCs对CMECs增殖、迁移、侵袭和血管生成的促进作用。转染miR-543抑制剂的hMSCs带来CMECs较弱的活力和血管生成能力。与单独转染 si-COL4A1 的 CMEC 相比，转染 si-COL4A1 和 miR-543 抑制剂的 CMEC 表现出较低的增殖、迁移、侵袭和血管生成。hMSCs-Exo 进入 MI 大鼠的心肌组织。在 MI 大鼠中注射 hMSCs-Exo 可减少梗死面积，减轻 MI 引起的损伤，并增加 Ki-67 的表达。hMSCs-Exo 通过转移 miR-543 和下调 COL4A1 表达促进 CMECs 的增殖、迁移、侵袭和血管生成。