TISSUE FACTOR ACTIVITY OF SYNCYTIOTROPHOBLAST PLASMA-MEMBRANES AND TUMORAL TROPHOBLAST CELLS IN CULTURE

During pregnancy, important modifications of hemostasis occur resultin g in mothers in hypercoagulability and the role of placental cells suc h as trophoblast cells has been hypothesized. In this study, we first showed that syncytiotrophoblast plasma membranes, isolated from normal human placenta, expressed a strong tissue factor (TF) activity. We th en studied TF activity of two continuous trophoblast cell lines (JEG-3 and BeWo) in comparison to human umbilical vein endothelial cells (HU VEC) and transformed human endothelial cells (ECV-304). TF assays were performed on intact detached confluent cells. Unstimulated JEG-3 and BeWo cells exhibited a very high;TF activity which slightly increased after 2 to 4 h TNF-alpha stimulation. In contrast, HUVEC and ECV-304 h ad a lower basal TF activity which was mainly inducible by TNF-alpha, with a maximum effect after 4 to 6 h stimulation. For both cell types, TF activity was decreased to basal value after 16-hour TNF-alpha stim ulation. These results support that trophoblast cells are able to expr ess TF but the involvement of this properly in the hemostatic physiolo gical changes observed during pregnancy, remains to be demonstrated.