Purpose microRNAs (miRs) are non-coding RNAs that silence mRNA translation and influence many biological processes. Peripheral blood miR expression patterns may provide mechanistic insight and novel biomarkers in Acute Coronary Syndromes (ACS). Our objective is to characterise whole blood miR expression following ACS and correlate this with miR target gene expression.

Methods 10 patients with Unstable Angina (UA) served as a reference group to which 20 patients with Myocardial Infarction (MI) were compared. miR were extracted from peripheral whole blood, expression of 754 species quantified by RT-qPCR and analysed using the Relative Quantification method. mRNA was hybridised on microarrays and gene expression analysis performed using probabilistic models.

Results Principal component analysis of whole genome microarray data showed clear discrimination between UA and MI groups at 7 and 30 days. Of particular interest is the differential expression of miR-20a between groups. Belonging to the miR-17-92 cluster, miR-20a is an endothelial derived miR involved in cardiovascular disease which has a regulatory role in smooth muscle cell proliferation. To assess possible involvement of miR-20a in endothelial dysfunction we compared its expression with miR-126. Comparison of expression showed correlation between miR and mRNA of putative targets.

Conclusions We have shown that it is possible to classify and differentiate ACS events using transcriptional profiling of miRs and mRNA in whole blood. We have identified a group of 9 miRs that discriminate UA and MI at 30 days. The correlation of miR126 and miR20a suggests a possible role for miR-20a in quantifying endothelial dysfunction post MI.