Plasma circulating extracellular RNAs in left ventricular remodeling post-myocardial infarction

Despite substantial declines in mortality following myocardial infarction (MI), subsequent left ventricular remodelling (LVRm) remains a significant long-term complication. Extracellular small non-coding RNAs (exRNAs) have been associated with cardiac inflammation and fibrosis and we hypothesized that they are associated with post-MI LVRm phenotypes. RNA sequencing of exRNAs was performed on plasma samples from patients with “beneficial” (decrease LVESVI ≥20%, n=11) and “adverse” (increase LVESVI ≥15%, n=11) LVRm. Selected differentially expressed exRNAs were validated by RT-qPCR (n=331) and analyzed for their association with LVRm determined by cardiac MRI. Principal components of exRNAs were associated with LVRm phenotypes post-MI; specifically, LV mass, LV ejection fraction, LV end systolic volume index, and fibrosis. We then investigated the temporal regulation and cellular origin of exRNAs in murine and cell models and found that: 1) plasma and tissue miRNA expression was temporally regulated; 2) the majority of the miRNAs were increased acutely in tissue and at sub-acute or chronic time-points in plasma; 3) miRNA expression was cell-specific; and 4) cardiomyocytes release a subset of the identified miRNAs packaged in exosomes into culture media in response to hypoxia/reoxygenation. In conclusion, we find that plasma exRNAs are temporally regulated and are associated with measures of post-MI LVRm. qPCR gene expression profiling from plasma of patients who underwent a myocardial infarction. Equal amount total RNA from each donor was extracted prior to gene expression analysis.