microRNA expression in epicardial mesothelial cells undergoing Epithelial-to-Mesenchymal Transition. Rattus norvegicus

Cardiac fibrosis is a detrimental pathophysiological state involved in a number of cardiovascular diseases. Myofibroblasts mediate fibrosis by excessive remodeling of the extracellular matrix, which ultimately leads to tissue stiffness and impaired heart performance. Recently, it was shown that a substantial fraction of cardiac myofibroblasts may originate from the epicardium through Epithelial-to-Mesenchymal Transition (EMT). We have developed a cellular model of EMT in which adult murine epicardium-derived cells are differentiated into myofibroblast-like cells in the presence of Interleukin-1beta, Tumor Necrosis Factor-alpha, or Transforming Growth Factor-beta. Using this model of EMT, the microRNAome was assessed by microRNA (miRNA) arrays. Subsequently, expression levels of differentially expressed miRNAs were validated by qPCR. These miRNAs were targeted by transfecting epicardium-derived cells with anti- or pre-miRs prior to EMT initiation. The ability of the anti- or pre-miRs to inhibit EMT was assessed on a number of phenotypic markers. In this study we have identified a number of miRNAs that potentially play an intrinsic role in cardiac EMT. We speculate that by targeting those miRNA, the onset and long-term progression of cardiac fibrosis can be substantially reduced. Overall design: Epicardial mesothelial cells were isolated and expanded from the epicardium of adult rats (8-10 weeks). Epithelial-to-mesenchymal Transition was induced by 10 ng/mL Interleukin-1beta, Tumor Necrosis Factor-alpha, or Transforming Growth Factor-beta1 for 48h. The assocciated differential microRNA expressions relative to a control treatment was computed by microRNA arrays. The experiment was conducted on biological quadruplicates for the control treatment and biological triplicates for cytokine treatments.