Differentially expressed microRNA profiles in exosomes from vascular smooth muscle cells associated with coronary artery calcification

Objective: The pathogenesis of coronary artery calcification (CAC) in coronary heart disease (CHD) is mediated by exosomes derived from vascular smooth muscle cells (VSMCs). However, little is known about their underlying mechanism. In this study, we aimed to investigate the differentially expressed miRNAs in VSMCs undergoing induced calcification. Methods: A cellular calcification model was established using the mouse VSMC line MOVAS-1. Calcium deposition was evaluated by Alizarin Red staining. Exosome sizes were determined by Nanoparticle Tracking Analysis (NTA), and exosome morphology was examined by transmission electron microscopy (TEM). The expression of exosome and calcification biomarkers was analyzed by quantitative real-time PCR (qPCR) and western blotting. Differential miRNA profiles were determined by deep sequencing and bioinformatics. Protein levels in VSMCs experiencing interference by a miR-324-3p inhibitor were detected by western blotting. Results: The MOVAS-1 calcification model was confirmed by Alizarin Red staining and expressional alteration of alpha-SMA, BMP-2, OPN, and MGP. Exosomes from the calcification model showed expression of exosomal biomarkers and regular exosome diameters, which caused significant calcification in MOVAS-1 cells. In total, 987 and 92 miRNAs were significantly upregulated and downregulated in exosomes from the cellular calcification model as compared with those from MOVAS-1 cells, respectively. Target genes of differential miRNAs were involved in various biological processes such as development, metabolism, and cellular component organization and biogenesis as well as multiple signaling pathways such as protein kinase B (AKT) signaling. The most differentially expressed miRNAs were validated by qPCR, which showed that mmu-let-7e-5p was downregulated and mmu-miR-324-3p was upregulated in exosomes from the MOVAS-1 cellular calcification model. The expression of IGF1R was increased, and the expressions of PIK3CA and MAP2K1 were reduced in MOVAS-1 transfected with a miR-324-3p inhibitor. Conclusion: microRNA profiles were significantly altered in exosomes from VSMCs undergoing calcification.