Establishment and characterization of in vitro decidualization in normal human endometrial stromal cells.

We established and characterized a novel experimental model of in vitro decidualization in normal human endometrial stromal cells. In a comparison of decidualization induction, 8-Br-cAMP showed the strongest ability to induce decidualization in stromal cells among four inducers examined: progesterone, medroxyprogesterone acetate, prostaglandin E2, and 8-Br-cAMP. The effects of 8-Br-cAMP were enhanced by prostaglandin E2 but not altered by medroxyprogesterone acetate. Both progesterone and medroxyprogesterone acetate activity was so weak that it took more than 2 weeks to induce in vitro decidualization. These results suggest that there are two independent decidualization signals in the in vitro decidualization, a cAMP-mediated signaling pathway and a progesterone receptor-mediated signaling pathway, and that cAMP-inducers are major factors in decidualization in vivo. Differential expressions of three membrane aminopeptidases on the stromal cells during the decidualization are also discussed.