Serum microRNA-499 and microRNA-208a as biomarkers of acute myocardial infarction.

OBJECTIVE Acute myocardial infarction (AMI) is a most serious cardiovascular disease with high morbidity and mortality. Novel biomarkers for AMI are explored continuous. MicroRNAs (miRNAs, miRs) are present in the circulation in a consistent, stable, and reproducible manner, attracting major interest of using circulating miRNAs as biomarkers. In plasma, miR-208a and miR-499 are considered to be the best candidate for AMI diagnosis. However, serum has slightly higher miRNA yields compared to plasma and the majority of archived samples are stored in form of serum, marking interesting to determine whether miR-208a and miR-499 in serum can be used as biomarkers for AMI. METHODS AMI was induced by coronary ligation and the serum and heart tissues were collected. The levels of miR-208a and miR-499 in serum and heart tissues were determined using TaqMan-based miRNA quantitative real-time polymerase chain reactions (qRT-PCRs). RESULTS Serum miR-208a was increased by 36-fold and 51-fold while miR-499 was elevated by 103-fold and 95-fold at 4 h and 24 h after AMI. Moreover, the expression level of miR-499 was significantly decreased in the myocardial infarct zone comparing to the remote zone or the sham group while miR-208a remained unchanged. CONCLUSION Serum miR-499 and miR-208a might be potential biomarkers for AMI. miR-499 might be released from damaged heart to the circulation.