Reproduction Abstracts

Introduction: During the establishment of pregnancy, extravillous trophoblast (EVT) must invade through the decidua to form a functional placenta. Impaired decidualization is associated with placental insufficiency, including preeclampsia. The mechanisms by which decidual cells interact with EVT remain largely unknown. We hypothesised that decidual–EVT interactions are critical for appropriate invasion.

Methods: Primary human endometrial stromal cells (HESC) were decidualized with estradiol 17β-methoxyprogesterone acetate cAMP or EVT conditioned media (CM) (n=3). Prolactin (PRL; decidual marker) was measured by ELISA. CM was collected from non-decidualized (nd) and decidualized (d) HESC. Cytotrophoblast isolated from 1st trimester placenta were cultured on Matrigel to differentiate to EVT and subjected to outgrowth and invasion assays (n=6). Proteins in EVT CM were identified by mass spectrometry.

Results and discussion: Decidualized CM significantly enhanced outgrowth (compared to nd CM; nd:100; d:161.6+28.4%; P<0.05) and invasion (nd:100; d:126.4+10.4%; P<0.05) of EVTs isolated from weeks 6 to 8 of gestation, whereas decidualized CM significantly suppressed outgrowth (nd:100; d:77.3+8.4%; P<0.05) and had no effect on invasion of EVTs isolated from weeks 10 to 12. Decidual CM induced EVT expression of proteins which promote cell migration/invasion (profilin-1). EVT CM induced HESC decidualization (control:10.7+3.8 mIU/l; EVT:82.0+19.9 mIU/l PRL; P<0.05). EVT CM contained progesterone (194.1+73.3 nmol/l; n=6), however HESC treatment with progesterone (50–300 nmol/l) could not stimulate decidualization to the same extent as EVT CM (31.5+6.5 mIU/l PRL). Proteomics revealed EVT CM also contained other proteins (nidogen, fibulin) known to stimulate decidualization.

Conclusion: Decidualization promoted EVT invasion and EVT CM induced HESC decidualization showing that decidual–EVT crosstalk is critical for appropriate EVT invasion and therefore placental formation.