A spatial transcriptomic approach to understanding coronary atherosclerotic plaque stability

ABSTRACT

Background
Coronary atherosclerotic plaques susceptible to acute coronary syndrome (ACS) have traditionally been characterized by their surrounding cellular architecture. However, with the advent of intravascular imaging, novel mechanisms of coronary thrombosis have emerged, challenging our contemporary understanding of ACS. These intriguing findings underscore the necessity for a precise molecular definition of plaque stability. Considering this, our study aimed to investigate the vascular microenvironment in patients with stable and unstable plaques using spatial transcriptomics.

Methods
Autopsy-derived coronary arteries were preserved and categorized by plaque stability (N = 5 patients / group). We utilized the GeoMx digital spatial profiling platform and Whole Transcriptome Atlas to link crucial histologic morphology markers in coronary lesions with differential gene expression in specific regions of interest, thereby mapping the vascular transcriptome. This innovative approach allowed us to conduct cell morphologic and spatially resolved transcriptional profiling of atherosclerotic plaques while preserving crucial intercellular signaling pathways.

Results
We observed intriguing spatial and cell-specific transcriptional patterns in stable and unstable atherosclerotic plaques, showcasing regional variations within the tunica intima and media. These regions exhibited differential expression of pro-inflammatory molecules (e.g., IFN-gamma, MHC Class II, pro-inflammatory cytokines) and pro-thrombotic signaling pathways. By employing lineage-tracing through spatial deconvolution of intimal CD68+ cells, we characterized unique, intraplaque subpopulations originating from endothelial, smooth muscle, and myeloid lineages with distinct regional locations associated with plaque instability. In addition, unique transcriptional signatures were observed in vascular smooth muscle and CD68+ cells among plaques exhibiting coronary calcification.

Conclusion
Our study sheds light on the distinct cell-specific and regional transcriptional alterations present in unstable arterial plaques. Furthermore, we characterize the first spatially-resolved, in situ evidence supporting cellular transdifferentiation and intra-plaque plasticity as significant contributors to plaque instability in human coronary atherosclerosis. Our results provide a powerful resource for the identification of novel mediators of ACS, opening new avenues for preventative and therapeutic treatments.