Increased t-PA and PAI-1 expression of cultured endothelial cells after stimulation with sera from women with preeclampsia

Abstract

Summary The objective was to determine the potential cytotoxicity of sera from patients with preeclampsia by investigating the influence of these sera on the expression of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) into the supernatant cultured human umbilical vein endothelial cells (HUVEC). This was an experimental study on cultured human endothelial cells in the Department of Obstetrics and Gynecology, University Hospital Aachen, Germany. We studied 19 females with preeclampsia, including 7 females with HELLP-syndrome. Nine pregnant and 12 non-pregnant normotensive females of comparable age and gestational age served as controls. HUVEC were isolated and cultured and second passage cells were then stimulated for 24 h with serum. PAI-1 and t-PA concentrations were determined in both maternal serum and the supernatant of cultured HUVEC by ELISA methods. The main outcome measures were the influence of preeclamptic sera on endothelial t-PA and PAI-1 excretion. Significantly higher concentrations of t-PA were detected in the maternal serum of patients with preeclampsia, but no significant differences in the PAI-1 levels were found. Levels of PAI-1 and t-PA in the HUVEC supernatant were significantly higher in the hypertensive group (median PAI-1 concentrations: preeclampsia: 12 868 ng/mg protein; pregnant/non-pregnant controls 7634/9005 ng/mg protein; median t-PA concentrations: preeclampsia: 65.0 ng/mg protein; pregnant/non-pregnant controls: 40.6/37.0 ng/mg protein, respectively). Only low concentrations of PAI-1 (219 ng/mg protein) was measured in the lysate of HUVEC, while t-PA could not be detected. Sera from patients with preeclampsia can stimulate cultured endothelial cells to synthesize larger amounts of t-PA and PAI-1. This elevation is due to endothelial cell activation and not to cell damage.