Department of Pharmacology, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
Department of Internal Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
Biomaterials. 2017 Nov;146:49-59. doi: 10.1016/j.biomaterials.2017.09.001. Epub 2017 Sep 4.
Extracellular matrix (ECM) plays a critical role in the provision of the necessary microenvironment for the proper regeneration of the cardiac tissue. However, specific mechanisms that lead to ECM-mediated cardiac regeneration are not well understood. To elucidate the potential mechanisms, we investigated ultra-structures of the cardiac ECM using electron microscopy. Intriguingly, we observed large quantities of micro-vesicles from decellularized right atria. RNA and protein analyses revealed that these contained exosomal proteins and microRNAs (miRNAs), which we referred to herein as ECM-derived extracellular vesicles (ECM-EVs). One particular miRNA from ECM-EVs, miR-199a-3p, promoted cell growth of isolated neonatal cardiomyocytes and sinus nodal cells by repressing homeodomain-only protein (HOPX) expression and increasing GATA-binding 4 (Gata4) acetylation. To determine the mechanisms, we knocked down Gata4 and showed that miR-199a-3p actions required Gata4 for cell proliferation in isolated neonatal cardiomyocytes and sinus nodal cells. To further explore the role of this miRNA, we isolated neonatal cardiac cells and recellularized into atrial ECM, referred here has engineered atria. Remarkably, miR-199a-3p mediated the enrichment of cardiomyocyte and sinus nodal cell population, and enhanced electrocardiographic signal activity of sinus nodal cells in the engineered atria. Importantly, antisense of miRNA (antagomir) against miR-199a-3p was capable of abolishing these actions of miR-199a-3p in the engineered atria. We further showed in Ang II-infused animal model of sinus nodal dysfunction that miR-199-3p-treated cardiac cells remarkably ameliorated and restored the electrical activity as shown by normalization of the ECG, in contrast to untreated cells, which did not show electrical recovery. In conclusion, these results provide clear evidence of the critical role of ECM, in not only providing a scaffold for cardiac tissue growth, but also in promoting atrial electrical function through ECM-derived miR-199a-3p.
细胞外基质 (ECM) 在为心脏组织的适当再生提供必要的微环境方面起着至关重要的作用。然而，导致 ECM 介导的心脏再生的确切机制尚不清楚。为了阐明潜在的机制，我们使用电子显微镜研究了心脏 ECM 的超微结构。有趣的是，我们观察到脱细胞右心房中有大量的微泡。RNA 和蛋白质分析表明，这些微泡包含外泌体蛋白和 microRNAs（miRNAs），我们将其称为细胞外基质衍生的细胞外囊泡（ECM-EVs）。ECM-EVs 中的一种特定 miRNA，miR-199a-3p，通过抑制同源盒蛋白（HOPX）的表达和增加 GATA 结合蛋白 4（Gata4）乙酰化，促进分离的新生心肌细胞和窦房结细胞的生长。为了确定机制，我们敲低了 Gata4，并表明 miR-199a-3p 在分离的新生心肌细胞和窦房结细胞中的增殖作用需要 Gata4。为了进一步探索这种 miRNA 的作用，我们分离了新生心脏细胞并重新植入到心房 ECM 中，这里称为工程化心房。值得注意的是，miR-199a-3p 介导了心肌细胞和窦房结细胞群体的富集，并增强了工程化心房中窦房结细胞的心电图信号活性。重要的是，miR-199a-3p 的反义核苷酸（antagomir）能够在工程化心房中消除 miR-199a-3p 的这些作用。我们进一步在窦房结功能障碍的 Ang II 输注动物模型中表明，与未处理的细胞相比，miR-199a-3p 处理的心脏细胞显著改善并恢复了电活动，表现为心电图的正常化，而未处理的细胞没有显示出电恢复。总之，这些结果提供了明确的证据，表明 ECM 不仅为心脏组织生长提供了支架，而且还通过 ECM 衍生的 miR-199a-3p 促进了心房的电功能。
