Tube Formation Assay for CTEPH Endothelial Cells

Tube formation assays were performed based on experiments described previously [26 (link)]. Each well of a pre-cooled 48-well plate was briefly coated with 150 μL Matrigel matrix (Corning, Tewksbury, MA, USA) and allowed to polymerize for 5 minutes at room temperature followed by 30 minutes at 37°C. Primary HPAECs or CTEPH-EC isolated from CTEPH patients (3 x 10⁴ cells per well) were seeded to the coated plate and incubated for 5h30min in EGM-2 alone or EGM-2 containing 50μM VER-155008 in a humidified incubator at 37°C with 5% of CO2. Five images were obtained from each well using TissueFAXS imaging system (TissueGnostics, Vienna, Austria).