In vitro analysis of trophoblast invasion.

Two methods are described for the study of human trophoblast invasion. When first-trimester placental villi are explanted on gels of a permissive extracellular matrix (ECM), a population of pure extravillous trophoblast cells grows out during the following several days from villous tips into the adjacent ECM. The outgrowths, which show a polarity and pattern of marker expression that replicates anchoring columns in vivo, may be used as the basis for preparation of small numbers of cells for gene expression studies, or for investigations of cell function and behavior. For quantitative studies, a standard trans-filter trophoblast migration experiment is described that starts from a homogeneous preparation of primary cells released from the tissue.