Detection and transport mechanisms of circulating microRNAs in neurological, cardiac and kidney diseases.

MicroRNAs are small non-coding RNA transcripts that modulate gene expression and translation through target mRNA destabilization and/or inhibition of protein synthesis. Various studies have aimed at elucidation of the role of these small molecules in the regulation of disease activity. Initially, microRNA were believed to merely act as intracellular mediators fine-tuning mRNA translation into proteins. Recently, the first studies have emerged demonstrating that microRNAs are also externalized from cells and transported in body fluids, thereby shuttling genetic information from a donor to a recipient cell. Thus, circulating microRNAs represent attractive non-invasive detectable markers to monitor onset/ progress of diseases. The present article outlines the quantification and biomarker use of microRNAs in various body fluids of patients with cardiac and kidney disease as well as neurological disorders.