Endothelial cell source dictates the expression and release of fibrinolytic markers in a proinflammatory environment.

BACKGROUND: Endothelial cells (ECs) provide a surface for molecular interactions, secreting various factors that govern hemostasis. Inflammatory cytokines can perturb the vascular microenvironment, potentially causing endothelial dysfunction and dysregulation of hemostasis. OBJECTIVES: To examine the fibrinolytic balance of ECs from different vascular beds and their response to proinflammatory stimuli. METHODS: Primary human umbilical vein ECs (HUVECs), human coronary artery ECs (HCAECs), and immortalized EA.hy926 cells were cultured under venous (2.5 dyne/cm(2)) and arterial (12 dyne/cm(2)) shear stress. ECs were stimulated with thrombin, interleukin 6, or tumor necrosis factor (TNF)-α for 24 hours. The expression of coagulation and fibrinolytic proteins was quantified by quantitative polymerase chain reaction and secreted proteins via ELISA or activity assay. Plasma clot lysis on ECs ± 300 pM tissue-type plasminogen activator (tPA) was monitored at 405 nm. RESULTS: Basal secretion of C-reactive protein, urokinase plasminogen activator (uPA), and plasminogen activator inhibitor-1 (PAI-1) was higher in HCAECs than in HUVECs, but tPA was similar in both. TNF-α stimulation of HCAECs increased secretion of tPA, uPA, and PAI-1. Levels of tPA/PAI-1 and uPA/PAI-1 were higher in media, as was free-active PAI-1. In contrast, stimulation of HUVECs did not significantly alter gene/protein levels. HCAECs and HUVECs delayed clot lysis relative to no-cell controls by 11 ± 8 minutes (P < .01) and 8 ± 6 minutes (P < .05) respectively, but were normalized by neutralizing PAI-1. TNF-α stimulation of HCAECs prolonged clot lysis in a PAI-1-dependent manner. CONCLUSION: HCAECs respond more potently to a proinflammatory environment than HUVECs, altering expression of fibrinolytic proteins and promoting a hypofibrinolytic response. These data highlight HCAECs as a model of coronary vasculature with potential for screening novel antithrombotic strategies.