Expression and localization of the urokinase-type plasminogen activator receptor (uPAR) in the human placenta.

In pregnancy the decrease in fibrinolytic activity has been described to date by many researchers. The placenta is a source of both plasminogen activator inhibitor type 2 (PAI-2) and type 1 (PAI-1). The PAI-2 was originally detected in the human placenta, which inhibits urokinase-type plasminogen activator (uPA) while it is unable to inhibit tissue type plasminogen activator (tPA). The urokinase-type plasminogen (uP) is activated by u-PA and urokinase-type plasminogen activator receptor (uPAR). We studied the expression and the localization of u-PAR in the human placenta by in situ hybridization, immunohistochemically and by use of Northern blot analysis. These data show that the decidualized endometorium have the cells with the greatest uPAR mRNA expression in the placenta, and syncytiotrophoblasts express lower level of uPAR mRNA.