Spatio-temporal expression patterns of microRNAs in remodelling and repair of the infarcted heart

MicroRNAs (miRNAs) are small, non-messenger RNAs, 20-22 nucleotides in size, which regulate gene expression at the post-transcriptional level. Typically, miRNAs target the 3' untranslated region (3'UTR) of mRNA transcripts leading to mRNA degradation or translational repression. The known dysregulation of miRNAs during cardiac ischemia and the crucial role of miRNA-dependent regulation of angiogenesis, fibrosis and hypertrophy present interesting therapeutic opportunities for repairing and regenerating the heart after myocardial infarction (MI). An understanding of the expression pattern and localization of deleterious and beneficial miRNAs during cardiac ischemia is necessary for the development of therapeutics designed to specifically treat the affected tissue and cell populations. This review focuses on the role and localization of key miRNAs implicated in MI while highlighting how their manipulation may promote cardiac repair.