The 9p21.3 coronary artery disease risk locus drives vascular smooth muscle cells to osteo-chondrogenic state.

Genome-wide association studies have identified common genetic variants at approximately 300 human genomic loci linked to CAD susceptibility. Among these genomic regions, the most impactful is the 9p21.3 CAD risk locus, which spans a 60 kb gene desert, encompasses about ∼80 SNPs in high linkage disequilibrium, and has no defined function. We used induced pluripotent stem cell (iPSC) lines from risk and non-risk donors at 9p21.3, as well as isogenic lines with a full haplotype deletion. iPSC-derived vascular smooth muscle cells (iPSC-VSMCs) were used for single-cell transcriptomics. iPSC-VSMCs resemble the heterogeneity observed in human coronary arteries, establishing the robustness of this model. Our analysis revealed that the 9p21.3 risk haplotype prompts VSMCs to acquire a novel cellular state showing osteochondrogenic features, and we identified a set of signature genes crucial for defining this transcriptional program. Our study provides new insights into the 9p21.3 risk locus and its role in driving disease-prone states in VSMCs.