Urokinase plasminogen activator (uPA) and its receptor (uPAR) in gestational tissues; Measurements and clinical implications

BACKGROUND: Urokinase plasminogen activator (uPA) and urokinase plasminogen activator receptor (uPAR) are central molecules for uPA/uPAR/plasmin-dependent proteolysis, which is thought to play a significant role in the development of pregnancy, as well as its many complications. OBJECTIVE: To measure the levels of uPA and uPAR in the placenta and myometrium, as well as in the foetal membranes and amniotic fluid. STUDY DESIGN: The study group consisted of 35 women with normal course of pregnancy, but with complications arising during delivery, which led to Caesarean section. Samples of placenta, myometrium, foetal membranes, amniotic fluid and blood were obtained at the time of operation. Tissue extracts were prepared. Measurements were made by the ELISA method. RESULTS: uPA and uPAR concentration in gestational tissues, including amniotic fluid, is 100-200 times higher than in plasma. Among tissues, the highest uPA level was found in placenta ( 1.32 +/- 0.48 ng/mg of protein), and the highest uPAR level in foetal membranes (3.33 +/- 1.20 ng/mg of protein). CONCLUSIONS: uPA and uPAR are present in all gestational tissues, in some in relatively high concentrations. Our results support the modern clinical hypothesis that fibrinolytic system can participate in mechanisms of such obstetric complications as pre-term pre-mature rupture of foetal membranes and placental abruption.