Transcoronary Concentration Gradients of Circulating MicroRNAs

Circulating levels of microRNA (miR) have been proposed as biomarkers for cardiovascular disease. To identify the heart as a potential source for miRs released into the circulation, we measured concentration gradients across the coronary circulation for muscle-enriched (miR-133a, miR-499, miR-208a), vascular (miR-126, miR-92a), leukocyte-related (miR-155), and platelet-enriched (miR-223) miRs. Circulating miRs were measured by TaqMan polymerase chain reaction in EDTA-plasma simultaneously obtained from the aorta and the coronary venous sinus in patients without coronary artery disease (n=7), with stable coronary artery disease (n=31), and with troponin-positive acute coronary syndromes (n=19). Circulating levels of the muscle-enriched miR-499 (>20-fold; P