Summary
During pregnancy, important modifications of hemostasis occur resulting in mothers in hypercoagulability and the role of placental cells such 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 then studied TF activity of two continuous trophoblast cell lines (JEG-3 and BeWo) in comparison to human umbilical vein endothelial cells (HUVEC) 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-α stimulation. In contrast, HUVEC and ECV-304 had a lower basal TF activity which was mainly inducible by TNF-a, 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-α stimulation. These results support that trophoblast cells are able to express TF but the involvement of this property in the hemostatic physiological changes observed during pregnancy, remains to be demonstrated.
