Morphological interactions of human first trimester placental villi co-cultured with decidual explants

Abnormalities of pregnancy such as pre-eclampsia and intrauterinegrowth retardation are characterized by shallow trophoblasticinvasion of the placental bed, the precise molecular pathophysiologyof which remains to be fully elucidated. An in-vitro model involvinga co-culture of first trimester placental villi and deciduaparietalis explants (of 8-12 weeks gestation) was developedand used to characterize the migration and local invasion oftrophoblast cells. Trophoblast proliferation (confirmed by Ki-67immunostaining), differentiation and loose attachment of placentalvilli to the underlying decidual epithelium or stroma occurredwithin the first 24 h of co-culture. This was followed by erosionof the syncytial layer of the placental villi and commencementof a progressive cytotrophoblast invasion after 48 h of co-culture,which continued until 120 h, when the experiments were terminated.E-cadherin was expressed at the interfaces between trophoblastcells within the villi, but expression of this adhesion moleculeseemed to be down-regulated in the invasive trophoblast cells.Our results suggest that the model could be useful in investigatingthe factors that control early human placentation and the feto-maternalinterface.