Single cell RNA sequencing (scRNAseq) of severely atherosclerotic coronary artery from Ossabaw miniature swine with metabolic syndrome

Abstract

IntroductionCoronary atherogenesis involves multiple signaling pathways and underlying gene expression. The atherogenic plasma milieu (excess lipoproteins, glucose, etc.) injures the endothelium, which is the initiating event of coronary plaque development. Subsequently, smooth muscle cells proliferate and migrate from the wall into the neointima, and blood cells and macrophages infiltrate the vessel wall and contribute to the growing plaque. Our goal was to characterize the gene expression in the heterogeneous cell population in this dynamic coronary artery pathology.MethodsWe performed single cell RNA sequencing (scRNAseq) on cells dispersed from the proximal 45 mm of the left anterior descending coronary artery of healthy pigs compared to separate plaque and wall cell dispersions from arteries of Ossabaw swine that had metabolic syndrome and were atherosclerotic for 23 months. Primary analysis scRNAseq data used t‐distributed stochastic neighbor embedding (T‐SNE) plots for an integrated analysis of the 3 cell preparations.ResultsMetabolic syndrome was confirmed by obesity, dyslipidemia, and hypertension. In vivo intravascular ultrasound (IVUS) of the entire artery revealed every stage of atherosclerosis from fatty streak to complex lesions having up to 70% occlusion with fibrofatty and calcified lesions. Cells (3,510) from healthy coronary artery expressed predominantly markers for endothelial (PECAM1), endocardial (CDH5, POSTN), and smooth muscle cells (ACTA2, TAGLN, CNN1, MYL9, CALD1, RGS5, MHY11). Overall, the healthy coronary artery cells were much more homogeneous than atherosclerotic plaque and wall cells. Wall cells (8,224) in atherosclerotic arteries expressed ~no (0.1%) endothelial, many smooth muscle, and fibroblast genes. Plaque cells (8,049) expressed ~no (0.1%) endothelial genes, robust smooth muscle marker genes, and a high abundance of early marker genes for chondrocytes, osteoblasts, monocytes, neutrophils, and macrophages.ConclusionProfound gene expression patterns were shown with scRNAseq in a clinically relevant model of coronary atherosclerosis. The striking heterogeneity of gene expression and marker genes for chondrocytes and osteoblasts in plaque cells indicate significant transdifferentiation and suggest further progression to severe coronary artery calcification.