Molecular Approaches to Cell-Cell Adhesion: From Leucocyte Extravasation to Embryo Implantation

Cell biology has emerged as one of the research areas where technological development and expansion of knowledge are particularly fast. A symposium on 'Molecular Approaches in Cell-Cell Adhesion' held in 2001 in Essen, Germany, provided a platform for discussing recent advances made in our understanding of the biology of cellular interactions that are mediated by direct membrane contact. Of particular interest are adhesion and signalling processes that are elicited at the apical cell pole of epithelia which is strategically positioned to regulate (resist or allow) such processes. The contributions selected from this symposium for inclusion in this special issue of Cells Tissues Organs are updated state-of-the-art reviews concentrating on two biological systems in which these interactions are crucial, i.e. vascular biology and embryo implantation. Cascades of events taking place during leukocyte rolling, adhesion and transmigration through the endothelium, including adhesion and signalling processes, do show striking similarities to what is going on between trophoblast and uterine epithelium during the initiation of embryo implantation. Experimental tools are now available to study these processes, not only the gene knockout technology but also techniques involving high resolution confocal microscopy combined with the study of signalling processes, and application as well as measurement of defined forces between cells at the nanoscale level using the force spectroscopy approach.