Utility of Circulating MicroRNAs as Clinical Biomarkers for Cardiovascular Diseases

Figure 1

A simplified flow chart depicting the steps involved in intracellular biogenesis of miRNA and their secretion in circulation. It is hypothesized that the mature miRNA can be secreted outside the cell via (1) exosomes when multivesicular body fuses with the cell membrane, (2) miRNA-protein complexes (Argonaute 2, nucleoplasmin), (3) HDL-miRNA complexes, (4) apoptotic bodies or microvesicles through interaction with membrane proteins, and (5) free miRNAs by natural spill or as by-products of dead cells. Various tissues and blood cells can contribute to the circulating miRNA pool. In otherwise undetectable levels in circulation, cardiac-specific miRNAs are released into the bloodstream in response to injury, such as AMI, and may serve as biomarkers for cardiovascular diseases.