Thrombomodulin in human gestational tissues: placenta, fetal membranes and myometrium

In intervillous space, thrombomodulin (TM) can be a key component of the protein C anticoagulant pathway that controls the balance between coagulation and anticoagulation/ /fibrinolysis via activation of protein C (APC). In our working hypothesis we assume that not only TM from the placenta, but also TM from myometrium might be engaged in this protective mechanism. To determine whether this is potentially possible, we decided to measure TM concentration in placenta and myometrium, and also in fetal membranes.

The study group consisted of 35 parturient women who delivered at term by cesarean section. Strips of placenta, fetal membranes and myometrium, as well as venous blood samples were collected during operation. The tissues were homogenized. TM was measured by immunoenzymatic method (ELISA). The concentration of TM antigen in placenta was 18.76 +/- 3.83 ng/mg proteins, in fetal membranes 8.57 +/- 1.64 ng/mg proteins and in myometrium 4.72 +/- 1.93 ng/mg proteins, while in blood plasma it was 0.063 +/- 0.016 ng/mg proteins.

It was shown for the first time that thrombomodulin is present in gestational myometrium and fetal membranes. The results support the hypothesis that not only placental TM, but also myometrial TM can participate in maintaining the fluidity of the blood in utero-placental circulation.