Spontaneous coronary artery dissection (SCAD) is an understudied cause of myocardial infarction primarily affecting women. It is not known to what extent SCAD is genetically distinct from other cardiovascular diseases, including atherosclerotic coronary artery disease (CAD). Here we present a genome-wide association meta-analysis (1,917 cases and 9,292 controls) identifying 16 risk loci for SCAD. Integrative functional annotations prioritized genes that are likely to be regulated in vascular smooth muscle cells and artery fibroblasts and implicated in extracellular matrix biology. One locus containing the tissue factor gene F3, which is involved in blood coagulation cascade initiation, appears to be specific for SCAD risk. Several associated variants have diametrically opposite associations with CAD, suggesting that shared biological processes contribute to both diseases, but through different mechanisms. We also infer a causal role for high blood pressure in SCAD. Our findings provide novel pathophysiological insights involving arterial integrity and tissue-mediated coagulation in SCAD and set the stage for future specific therapeutics and preventions.

BACKGROUND: Vascular smooth muscle cells (SMCs) plasticity is a central mechanism in cardiovascular health and disease. We aimed at providing cellular phenotyping, epigenomic and proteomic depiction of SMCs derived from induced pluripotent stem cells and evaluating their potential as cellular models in the context of complex diseases. METHODS: Human induced pluripotent stem cell lines were differentiated using RepSox (R-SMCs) or PDGF-BB (platelet-derived growth factor-BB) and TGF-β (transforming growth factor beta; TP-SMCs), during a 24-day long protocol. RNA-Seq and assay for transposase accessible chromatin-Seq were performed at 6 time points of differentiation, and mass spectrometry was used to quantify proteins. RESULTS: Both induced pluripotent stem cell differentiation protocols generated SMCs with positive expression of SMC markers. TP-SMCs exhibited greater proliferation capacity, migration and lower calcium release in response to contractile stimuli, compared with R-SMCs. Genes involved in the contractile function of arteries were highly expressed in R-SMCs compared with TP-SMCs or primary SMCs. R-SMCs and coronary artery transcriptomic profiles were highly similar, characterized by high expression of genes involved in blood pressure regulation and coronary artery disease. We identified FOXF1 and HAND1 as key drivers of RepSox specific program. Extracellular matrix content contained more proteins involved in wound repair in TP-SMCs and higher secretion of basal membrane constituents in R-SMCs. Open chromatin regions of R-SMCs and TP-SMCs were significantly enriched for variants associated with blood pressure and coronary artery disease. CONCLUSIONS: Both induced pluripotent stem cell–derived SMCs models present complementary cellular phenotypes of high relevance to SMC plasticity. These cellular models present high potential to study functional regulation at genetic risk loci of main arterial diseases.

Spontaneous coronary artery dissection (SCAD) is an understudied cause of acute myocardial infarction primarily affecting women. It is not known to what extent SCAD is genetically distinct from other cardiovascular diseases, including atherosclerotic coronary artery disease (CAD). Through a meta-analysis of genome-wide association studies including 1917 cases and 9292 controls of European ancestry, we identified 17 risk loci, including 12 new, with odds ratios ranging from 2.04 (95%CI 1.77-2.35) on chr21 to 1.25 (95%CI 1.16-1.35) on chr4. A locus on chr1 containing the tissue factor gene (F3), which is involved in blood coagulation cascade, appears to be specific for SCAD risk. Prioritized genes were mainly expressed in vascular smooth muscle cells and fibroblasts of arteries and are implicated predominantly in extracellular matrix biology (e.g. COL4A1/A2, HTRA1 and TIMP3). We found that several variants associated with SCAD had diametrically opposite associations with CAD suggesting that shared biological processes contribute to both diseases but through different mechanisms. We also demonstrated an inferred causal role for high blood pressure, but not other CAD risk factors, in SCAD. Our findings provide novel pathophysiological insights involving arterial integrity and tissue-mediated coagulation in SCAD and set the stage for future specific therapeutics and prevention for this disease.