MORPHOLOGICAL INTERACTIONS OF HUMAN FIRST TRIMESTER PLACENTAL VILLI COCULTURED WITH DECIDUAL EXPLANTS

Abnormalities of pregnancy such as pre-eclampsia and intrauterine grow th retardation are characterized by shallow trophoblastic invasion of the placental bed, the precise molecular pathophysiology of which rema ins to be fully elucidated. An in-vitro model involving a co-culture o f first trimester placental villi and decidua parietalis explants (of 8-12 weeks gestation) was developed and used to characterize the migra tion and local invasion of trophoblast cells, Trophoblast proliferatio n (confirmed by Ki-67 immunostaining), differentiation and loose attac hment of placental villi to the underlying decidual epithelium or stro ma occurred within the first 24 h of co-culture. This was followed by erosion of the syncytial layer of the placental villi and commencement of a progressive cytotrophoblast invasion after 48 h of co-culture, w hich continued until 120 h, when the experiments were terminated. E-ca dherin was expressed at the interfaces between trophoblast cells withi n the villi, but expression of this adhesion molecule seemed to be dow n-regulated in the invasive trophoblast cells. Our results suggest tha t the model could be useful in investigating the factors that control early human placentation and the fete-maternal interface.