Single Cell RNA Sequencing of Human Pulmonary Endarterectomy Specimen Reveals Distinct Cell Populations and Gene Profiles

Purpose

Chronic thromboembolic pulmonary hypertension (CTEPH), is a progressive condition characterized by persistent elevation in pulmonary artery pressure due to thromboembolic occlusion of the pulmonary arteries. Little is known about the cells that make up the cast of pulmonary endarterectomy (PEA) and its immune microenvironment. Here we report a map of the cellular landscape of the human PEA specimen using single-cell RNA sequencing.

Methods

Five human PEA specimen from the proximal pulmonary arteries were collected from CTEPH patients who underwent PEA surgery. The protocol was approved (University Health Network, REB# 18-5892). 10x sample processing and cDNA library preparation was prepared using the 10x Genomics Single Cell Reagent Kit. Molecular analysis, Western blot, and immunohistochemistry were also performed.

Results

The transcriptional profiles of 12598 cells obtained by fractionating fresh tissues from five CTEPH patients after PEA are presented in Figure 1. Using gene expression patterns and immunohistochemical examinations, we identified 18 discrete cell populations with distinct endothelial cell, smooth muscle cell, monocyte/macrophage, T cell, B cell, and NK-like cell characteristics. Transcription of endothelin-1 was observed in endothelial cells from every patient. The expression of endothelin-1 was confirmed by Western blot and immunohistochemistry in the PEA specimen from an additional 14 CTEPH patients undergoing surgery.

Conclusion

Single cell RNA sequencing demonstrates a large population of inflammatory cells combined with endothelial cells and smooth muscle cell in the cast of PEA. Endothelin-1 expression by endothelial cells may contribute to the development of PH in patients with CTEPH.