Haemostatic properties of human pulmonary and cerebral microvascular endothelial cells.

Little is known on the haemostatic profiles of human microvascular endothelial cells (MVEC) from different tissues. In addition it is not known whether MVEC from patients display the same haemostatic pattern as MVEC coming from healthy controls. To address these questions MVEC from human lung and brain were isolated and stimulated with tumour necrosis factor alpha (TNF) and E. coli lipopolysaccharide (LPS) for 24 h. The level and the kinetics of procoagulant activity (PCA) and thrombomodulin (TM) expression were found to be different depending on the tissue of origin and on the agonist used. In particular, the inducible PCA was higher in lung than in brain MVEC, an observation that may be related to the frequency of lung involvement in septic shock. Differences were also observed for tissue plasminogen activator (t-PA) and plasminogen activator inhibitor 1 (PAI-1) with MVEC supernatants or cell lysates. These variables were then measured in lung MVEC purified from patients with acute respiratory distress syndrome (ARDS) and compared to controls. Cells from ARDS patients constitutively expressed more PCA and PAI-1 than controls. The fibrinolytic potential, expressed as t-PA/PAI-1 ratio, was lower in ARDS than in lung MVEC. It is concluded that MVEC display different haemostatic features depending on the tissue they come from and that lung MVEC from ARDS patients present a procoagulant profile when compared with those from controls.