Abstract

Coronary Artery Disease (CAD) is the leading cause of death in developed countries. Studies have indicated that ischemic tissues may release exosome-carried microRNAs (miRNAs) into circulation. miRNAs are a class of small, endogenous, noncoding RNAs that regulate the expression of multiple target genes at the posttranscriptional level on the basis of sequences that are complementary to target mRNA molecules. However, the prognostic role of exosomal miRNAs in CAD remains unclear. In this study, we compared the profiles of circulating exosomal miRNA expression in patients with angiographically assessed absent and well-developed collateral vessels. A total of 109 patients who underwent coronary angiography were recruited, including 44 patients with CAD and well-developed collateral circulation, 31 patients with no collateral flow (as indicated by their Rentrop scores), and 34 patients with patent coronary arteries (control group). miRNAs were then extracted from exosomes collected from peripheral blood and amplified, and a miRNA microarray system was used to profile the expression of these miRNAs in the exosomes. Subsequently, the effects of specific miRNAs on angiogenesis were identified in vitro. On the basis of the array data, miRNAs with high differential expression ratios along with Grade 0-2 collateral flow were selected. Among patients with no collateral flow, the top five overexpressed candidate miRNA markers were miR-29a, miR-592, miR- 518e, miR-32 and miR-766. Similarly, among patients with adequate collateral perfusion, the top five overexpressed miRNAs were miR-300, miR-576-3p, miR-642, miR-620 and miR-1255a. As a next step, the angiogenic ability and proangiogenic signaling pathway of two specific angiogenesis-related miRNAs (i.e., miR-300 and miR-29a) with high differential expression ratios were determined. According to the microarray data and study results, miRNAs with high expression levels can be used as biomarkers to distinguish between types of collateral circulation in patients with CAD and can be used in diagnostic or prognostic applications for high-risk patients with CAD. These findings may serve as a reference for the development of noninvasive and cost-effective approaches aimed at identifying the high risk of CAD and for the development of novel therapeutic targets for vascular diseases, including CAD with impaired collateral angiogenesis.

Keywords: Coronary artery disease; Collateral circulation; microRNA; Microarray analysis