DIFFERENT FIBRINOLYTIC POTENTIAL IN CULTURED HUMAN ADULT AND UMBILICAL VEIN ENDOTHELIAL-CELLS

Tissue-type plasminogen activator (t-PA), urokinase plasminogen activator (u-PA) and plasminogen activator inhibitor-1 (PAI-1) are secreted by cultured endothelial cells. Human umbilical vein endothelial cells are often used in studies of the role of endothelial cells in the regulation of fibrinolysis. It has not been established whether these cells differ in fibrinolytic potential compared to adult endothelial cells. In this study mRNA and antigen levels of PAI-1, t-PA and u-PA in human umbilical vein endothelial cells and human adult vein endothelial cells cultured under identical conditions were compared. The amount of PAI-1 mRNA and antigen differed drastically between the two cell types. In passage 4, the level of PAI-1 mRNA in human adult vein endothelial cells was 25% and the PAI-1 antigen level 37% of that in human umbilical vein endothelial cells. The levels of t-PA and u-PA mRNA and antigen were lower (t-PA approximately 10-fold and u-PA approximately 100-fold) than the PAI-levels, and did not differ statistically significantly between the two cell types. In primary cultures, the level of PAI-1 mRNA in human adult vein endothelial cells was 50% and the PAI-1 antigen level 37% of that in human umbilical vein endothelial cells. The present study indicates that there are substantial differences in fibrinolytic potential between adult and umbilicial vein endothelial cells in culture.