[Adhesion molecules and trophoblastic invasion]

At the time of implantation, the extracellular matrix proteins laminin and fibronectin are abundant in the decidua and are distributed pericellularly around each individual stromal cells. First trimester human trophoblast express both laminin and fibronectin receptors, specifically the alpha 1 beta 1, alpha 5 beta 1, alpha 6 beta 1 and alpha 6 beta 4 integrin heterodimers. We have demonstrated that in vitro adhesion of first trimester human trophoblast to purified extracellular matrix proteins and to purified decidual stromal cell monolayers can be inhibited by monoclonal antibodies directed against appropriate integrin subunits and by synthetic peptides containing an RGD sequence. We have also examined the downstream events of trophoblast matrix adhesion, such as integrin mediated signal transduction and the production of metalloproteinases. The implications of these interactions are discussed.