Abnormal levels of urokinase plasminogen activator protein and tissue plasminogen activator activity in human aortic aneurysms

Objective: To measure the concentrations and activities of plasminogen acti vators and plasminogen activator inhibitors in human abdominal aneurysms. Design: Laboratory study. Setting: University hospital, Sweden. Material: Biopsy specimens from 12 abdominal aortic aneurysms and 8 normal aortas (controls). Intrerventions: Tissues were homogenised and eluted. The supernatants were assayed for antigens of tissue and urokinase plasminogen activator and plas minogen activator inhibitor 1 and 2. The activities of tissue plasminogen a ctivator and plasminogen activator inhibitor-1 were assayed by ELISA. Froze n sections were immunostained for tissue and urokinase plasminogen activato rs and for plasminogen activator inhibitor-1. Main outcome measures: Concentrations and activities of these activators an d inhibitors. Results: The concentration of urokinase plasminogen activator antigen was h igher in aneurysmal walls than in normal aortas. it was detected immunohist ochemically in aneurysmal but not in normal aortas. The concentration (and the detection immunohistochemically) of tissue plasminogen activator was eq ual in aneurysmal and normal aortas, but its activity was reduced in the an eurysmal wall. Plasminogen activator inhibitor-1 did not differ significant ly between the groups. Conclusions: Urokinase plasminogen activator may be responsible for the dig estion of the media of the aorta and the development of an aneurysm. Reduce d activity of tissue plasminogen activator may be responsible for thrombosi s in the aneurysm.