Trophoblast migration during human placental implantation.

During the process of implantation in humans, fetal trophoblast cells invade and migrate into the maternal decidua. During this migration, trophoblast cells destroy the wall of the maternal spiral arteries, converting them from muscular vessels into flaccid sinusoidal sacs. This vascular transformation is important to ensure an adequate blood supply to the feto-placental unit. Both cell-cell and cell-matrix interactions are important for trophoblast invasion of the decidual stroma and decidual spiral arteries. Cell-matrix adhesions are mediated by specific receptors, mostly belonging to the family of integrins. Signals transduced to the cells from the matrix via integrins could play a pivotal role in the control of cellular behaviour and gene expression, such as metalloproteinases that facilitate matrix degradation and tissue remodelling. This review focuses on the role of integrins and extracellular matrix in trophoblast cell migration, trophoblast invasion of the decidual spiral arteries and matrix degradation by trophoblast during implantation.