This study mapped mesenchymal cell populations during the progression of human coronary atherosclerosis and explored their associations with disease processes in human carotid plaques.<h4>Methods and results</h4>Multiplex immunostaining protocols based on single-cell RNA sequencing-validated markers were established to detect SMCs, putatively SMC-derived mesenchymal cell subsets expressing osteoprotegerin or lumican, and macrophages in sections of left anterior descending arteries from forensic autopsies. Here, LUM is linked to coronary atherosclerosis.