Human placental trophoblast culture: one-sided and two-sided models.

The investigation of human placental nutrient transfer and hormonal secretion presents a particular challenge because these processes depend on the intactness and orientation of the unicellular epithelial sheet of villous syncytiotrophoblast that mediates them. The isolated perfused placental cotyledon retains the architecture of the villi and has been very useful, but the presence of the non-trophoblastic placental cell types, and the complication of the effects of perfusion medium flows can be disadvantageous in certain types of study particularly at a cellular or molecular level. On the other hand, the development of methods for isolating syncytiotrophoblast microvillous and basal membrane vesicles has recently provided a great impetus to our understanding of the characteristics of the transport systems on these two membranes. Nevertheless, there is currently the need for intact pure trophoblast cell models for investigating mechanisms of transtrophoblast transfer and hormone secretion, and their relationships to intracellular metabolism. The present paper outlines initial steps in the development and characterization of two such models.