Single cell RNA sequencing of distal thrombus tissue from CTEPH patients

Our current understanding of CTEPH pathobiology is primarily derived from cell-based studies limited by the use of specific cell markers or phenotypic modulation in cell culture. Therefore, our main objective is to identify the multiple cell types that comprise the CTEPH thrombus and to study their dysfunction. Here we used single cell RNA sequencing (scRNAseq) of tissue removed at the time of pulmonary endarterectomy (PEA) surgery from five patients to identify the multiple cell types. Our scRNAseq identify the multiple cell types including macrophages, T cells, and smooth muscle cells, that comprise CTEPH thrombus. Notably, multiple macrophage subclusters were identified but broadly split into two categories, with the larger group characterized by an upregulation of inflammatory signaling predicted to promote pulmonary vascular remodeling. Both CD4+ and CD8+ T cells were identified and likely contribute to chronic inflammation in CTEPH. Smooth muscle cells were a heterogeneous population, with a cluster of myofibroblasts that express markers of fibrosis and are predicted to arise from other smooth muscle cell clusters based on pseudotime analysis. Lastly, our analysis identified protease-activated receptor 1 (PAR1) as a potential therapeutic target that links thrombosis to chronic PE in CTEPH The thrombus is processed for single cell RNA sequencing (scRNAseq). After rehydration of methanol-fixed cells, libraries were prepared using the 10X Genomics Single Cell Protocol through the Duke Human Vaccine Institute Genetics Analysis Core. The data was analyzed in collaboration with the Duke Center for Genome Biology.