MiRNA-Seq of myocardial cell types from mouse

MicroRNAs are small, non-coding RNAs that posttranscriptionally regulate gene expression and have been been implicated in a wide variety of physiological processes and diseases including cardiovascular disease. Here, we sought to obtain an inventory of the entire small RNA transcriptomes of the major cell fractions of the mouse heart. To this end, we devised a cell isolation strategy, starting with retrograde perfusion of the isolated heart (Langendorff preparation), followed by fractionation into myocytes, endothelial cells, fibroblasts and macrophages using magnetic- and fluorescence-activated cell sorting. We detected 307 unique and individual transcripts that were confidently annotated as microRNAs. Interestingly, several of those microRNAs at the upper end of the expression spectrum also exhibited very pronounced cell type specificity when compared to the other myocardial cell types. We found miR-21 to be the highest-expressed microRNA in cMPs, constituting about one quarter of all microRNA molecules in this cell type.