Understanding the Impact of Hypoxia on Pulmonary Artery Endothelial Cells in Chronic Thromboembolic Pulmonary Hypertension Patients.

Pulmonary endarterectomy (PEA) specimens provide a unique source of endothelial cells (ECs) to model chronic thromboembolic pulmonary hypertension (CTEPH) in vitro. This study investigates the impact of chronic hypoxia on PEA-derived ECs, focusing on mechanisms of endothelial dysfunction and vascular remodeling. ECs from PEA specimens (EC-CTEPH) and controls were exposed to normoxia, hypoxia, and reoxygenation. Cell morphology, proliferation, migration, and expression of angiogenic and hypoxia-responsive genes were assessed. Pharmacological HIF stabilization with dimethyloxalylglycine (DMOG) was compared with hypoxia. Oxidative stress responses were evaluated using hydrogen peroxide. EC-CTEPH showed impaired adaptation to hypoxia, with reduced induction of glycolytic and angiogenic genes, altered morphology, delayed wound closure, and persistent oxidative stress after reoxygenation, consistent with defective hypoxia sensing. DMOG partially restored metabolic gene expression, indicating improved adaptation through HIF stabilization. Despite elevated basal ROS levels, oxidative challenge did not trigger adaptive glycolytic or angiogenic responses and induced distinct transcriptional profiles compared with controls. CTEPH endothelial cells display an altered response to hypoxia and oxidative stress, consistent with impaired hypoxia sensing and stress adaptation. This model highlights maladaptive endothelial features and provides a framework for future studies exploring HIF-targeted approaches in CTEPH.