Summary

The placenta is a highly vascularized organ with fetal and maternalblood supply. Syncytiotrophoblasts (STB),which line the placentavillous are possibly involved in local hemostatic mechanisms.The aim of this study was to evaluate the levels of tissuefactor (TF) and its inhibitors, tissue factor pathway inhibitor(TFPI,TFPI-2), in STB model within hemostatic and inflammatoryenvironments. Human primary STB cell cultures were characterizedby vascular and hormonal markers. TF and TFPImRNA expression, protein levels and activity were determinedand compared to human umbilical vein endothelial cells (HUVEC). High levels of TF were demonstrated in STB cellscompared to low levels in HUVEC. In contrast, STB expressedlower TFPI levels than HUVEC. LPS and TNFa increased thehigh constitutive TF in STB, whereas LPS and IL-1a furtherreduced TFPI levels. The procoagulant tendency of STB identifiedby us may reflect the physiological need for immediateinhibition of hemorrhage in the placental inter-villous spaces inbasal and inflammatory conditions.This hemostatic balance maybe critical for normal placental function and pregnancy outcome.