Comparison of fibrinolytic activities of human and bovine endothelial cells.

Human aortic (HAE), human umbilical vein (HUVE), and bovine aortic (BAE) endothelial cells were compared in their synthesis and release of fibrinolytic components during culturing. After isolation, the cultures were grown to confluency and then studied under identical conditions for release of tissue plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI) into serum-free medium. HAE cells released 10 times more t-PA antigen than HUVE cells, and the respective cell lysates also contained comparably higher values. Free PAI capacity was found in the conditioned media of both HAE and HUVE cells. BAE cell t-PA release was much lower than that of the HAE cells, and free inhibitor capacity was not found in the conditioned medium. BAE cells contained significant amounts of PA activity in cell membrane-bound form. This PA activity on the cell surface was not stimulated by addition of CNBr fibrinogen fragments but could be partially inhibited by activated bovine PAI and antibodies against human t-PA and urokinase PA, respectively.