Studies on the role of adhesive proteins in maintaining pregnancy

It is well known that maternal fibrinogen (Fg) and factor X III are essential for maintaining early pregnancy. We studied their role by analysis of clinical reports and immunohistochemical investigation. Methods: (1) We analyzed the pregnancy cases of congenital afibrinogenemia and congenital factor X III deficiency. (2) Immunohistochemical staining of Fg, subunit A of factor X III (X IIIA) and fibronectin (Fn) were performed in the human implantation site, placenta, and endometrial cells cultured in serum-free medium. Results: (1) Afibrinogenemia needed to be administrated Fg from 4 weeks' gestation (4 wG), and factor X III deficiency needed factor X III concentrate from 5 wG, in order to prevent abortion. (2) Implantation tissues: Fg, cellular X III(A) and Fn were present at the decidual stroma around invasive cytotrophoblasts at 5 wG. X III(A)-positive cells coincided with LN-5-positive macrophages. Placenta: Fg, cellular X III(A) and Fn were present in the decidual layer. Endometrial culture cells: Fn was secreted by spindle-like shaped cells. X III(A) was secreted by round-shaped cells. Conclusion: Maternal Fg and factor X III are essential just after 4 similar to 5 wG, and in that period they and Fn are present abundantly in decidual stroma around invasive cytotrophoblasts. It is concluded that when cytotrophoblasts invade endometrium maternal Fg, factor X III and Fn are concerned with cytotrophoblasts' anchoring as adhesive proteins.