HEMOSTATIC PROPERTIES OF HUMAN PULMONARY AND CEREBRAL MICROVASCULAR ENDOTHELIAL-CELLS

Little is known on the haemostatic profiles of human microvascular end othelial cells (MVEC) from different tissues. In addition it is not kn own whether MVEC from patients display the same haemostatic pat tern a s MVEC coming from healthy controls. To address these questions MVEC f rom human lung and brain were isolated and stimulated with tumour necr osis factor alpha (TNF) and E. coli lipopolysaccharide (LPS) for 24 h. The level and the kinetics of procoagulant activity (PCA) and thrombo modulin (TM) expression were found to be different depending on the ti ssue of origin and on the agonist used. In particular, the inducible P CA was higher in lung than in brain MVEC, an observation that may be r elated to the frequency of lung involvement in septic shock. Differenc es were also observed for tissue plasminogen activator (t-PA) and plas minogen activator inhibitor 1 (PAI-1) with MVEC supernatants or cell l ysates. 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 PC A and PAI-1 than controls. The fibrinolytic potential, expressed as tP A/PAI-1 ratio, was lower in ARDS than in lung MVEC. It is concluded th at MVEC display different haemostatic features depending on the tissue they come from and that lung MVEC from ARDS patients present a procoa gulant profile when compared with those from controls.