PROGESTATIONAL REGULATION OF HUMAN ENDOMETRIAL STROMAL CELL TISSUE FACTOR EXPRESSION DURING DECIDUALIZATION

Decidualized endometrial stromal cells from mid- to ate secretory phas e and decidual cells from gestational human endometrium displayed prom inent immunohistochemical staining for tissue factor, a primary initia tor of hemostasis. Consistent with the regulation by progesterone of t he decidualization process in vivo, medroxy-progesterone acetate eleva ted the tissue factor content of primary stromal cell cultures 8-fold over basal values. This increase paralleled the release of immunoreact ive PRL, a marker of decidualization. The induced, as well as basal, t issue factor displayed full functional activity and the expected elect rophoretic mobility (46 kilodaltons). Moreover, Northern analysis of R NA from cultured stromal cells indicated that medroxyprogesterone acet ate increased tissue factor mRNA levels approximately 10-fold relative to control levels. In contrast, cultured stromal cell tissue factor p rotein content and mRNA levels were unaffected by exogenous estradiol. These findings indicate that enhancement of endometrial stromal cell tissue factor content is associated with progesterone induction of the decidualization process. In humans, trophoblastic invasion of the end ometrial vasculature during blastocyst implantation risks hemorrhage. Therefore, increases in perivascular decidual cell tissue factor expre ssion could serve to promote periimplantational endometrial hemostasis .