Endothelial cell interactions surface

Selectins are a family of plasma membrane lectins that mediate cell-cell recognition and adhesion in a wide range of cellular processes. One such process is the movement of immune cells (T lymphocytes) through the capillary wall, from blood to tissues, at sites of infection or inflammation (Fig. 7-33). At an infection site, P-selectin on the surface of capillary endothelial cells interacts with a specific oligosaccharide of the glycoproteins of circu-... 

Massia, S. P, Hubbell, J. A. Human endothelial cell interactions with surface-coupled adhesion peptides on a nonadhesive glass substrate and two polymeric biomaterials. Journal of Biomedical Materials Research. 1991, 25, 223-242. 

Porte-Durrieu, M. C., Labrugere, C., Villars, F., Lefebvre, F., Dutoya, S., Guette, A., Btxdenave, L., and Baquey, C. (1999), Development of RGD peptides grafted onto silica surfaces XPS characterization and human endothelial cell interactions, J. Biomed. Mater. Res. 46(3) 368-375. 

FIGURE 14.16 Schematic view of the blood-brain barrier. Endothelial cells form a continuous layer covering the inner surface of blood microvessels. At the point of contacts with brain tissues, these endothelial cells interact with pericytes and astrocytes. Nerve ending with specific neurotransmitters can also be observed. The light junctions (TJ) that link endothelial cells act as a physical barrier that blocks the paraceUular route and forces the molecular traffic to take the transceUijlar pathway (double arrows). 

Essentially as a result of its ability to bind to basic sites, heparin interacts with many proteins.398 Although most of these interactions (such as that with protamine, a basic protein frequently used to neutralize heparin399) are probably not of biological significance, binding to plasma proteins and to proteins exposed on the surface of endothelial cells has an important influence on the circulation system. 

Returning to bacteria, PC also appears to play a role in infection of humans by pathogenic strains/species by allowing colonization and invasiveness due to interaction with appropriate receptors on host endothelial cells (reviewed by Harnett and Harnett, 1999). This may act as a double-edged sword, however, as the PC on the surface of the bacteria can be targeted by both the innate and adaptive immune responses and indeed such responses appear to play a role in the control of H. influenzae and S. pneumoniae, respectively, in humans (reviewed by Harnett and Harnett, 1999). 

Screening the molecular heterogeneity of receptor expression in endothelial cell surfaces is required for the development of vascular-targeted therapies. First, as opposed to targeting purified proteins as discussed above, membrane-bound receptors are more likely to preserve their functional conformation, which can be lost upon purification and immobilization outside the context of intact cells. Moreover, many cell surface receptors require the cell membrane microenvironment to function so that protein-protein interaction may occur. Finally, combinatorial approaches may allow the selection of cell membrane ligands in a functional assay and without any bias about the cellular surface receptor. Therefore, even as yet unidentified receptors may be targeted. 

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