Plasminogen activators and inhibitors are transcribed during early macaqueimplantation

Plasminogen activators and inhibitors may be important early in primate imp lantation but evidence for this is sparse in non-human primates. We define the expression of urokinase type plasminogen activator (uPA), tissue-type p lasminogen activator (tPA), plasminogen activator inhibitor type 1 (PAI-1) and type 2 (PAI-2), the receptor for uPA (uPAR) and fibrin/fibrinogen in mo nkey implantation sites. In situ hybridization and immuno-histochemical loc alization of rhesus monkey implantation sites (day 15-16 postovulation) ind icate: (1) uPA mRNA is localized to placental trophoblast, epithelial plaqu e and endometrial stroma. (2) tPA mRNA is mainly expressed in glandular cel ls of endometrium. (3) PAI-1 expression is linked to a specific population of trophoblasts that confront maternal cells, adding support to our view th at it has a regulatory role in trophoblast invasion. (4) Localization of tP A antigen confirms that uterine glands are the major source of tPA and that it is also closely associated with fibrin(ogen) suggesting its possible fu nction during implantation is fibrinolysis. (5) Unlike uPA mRNA, however, t he distribution of uPA protein and its cell surface receptor uPAR suggests that it mediates trophoblast invasion and plays a significant role in angio genesis. (6) PAI-2, the inhibitor associated with pregnancy in humans, was found in unidentified cells located specifically along the maternofetal jun ction. This localization adjacent to areas of cell death at the maternofeta l junction implies that it may have a role as a protective curtain with ant i-apoptotic function. In conclusion our results suggest that gene expressio n of PAs and PAIs in early implantation sites are tissue-specific, location -sensitive and function-related. (C) 2001 Harcourt Publishers Ltd.