18 Proteomic Analysis of Plasma Membrane Proteins in an In Vitro Blood-Brain Barrier Model Sophie Duban-Deweer, Johan Hachani, Barbara Deracinois, Roméo Cecchelli, Christophe Flahaut and Yannis Karamanos Laboratoire de Physiopathologie de la Barrière Hémato-Encéphalique, Université d'Artois, Lens France 1. Introduction Although several cell types have important regulatory roles in the induction and maintenance of a properly functioning blood-brain barrier (BBB) [Abbott et al., 2006; Armulik et al., 2010], it is clear that brain capillary endothelial cells (BCECs) constitute the barrier per se in histological terms. In the central nervous system’s blood vessels, BCECs are closely interconnected by tight junctions and form a continuous, circular tube lining the basal membrane in which pericytes are embedded. The basal membrane surface is itself covered by a continuous sleeve of astrocyte endfeet (Fig. 1). The BBB is one of the most important physiological structures in the maintenance of brain homeostasis. Endothelial cells Pericyte Astrocyte end-foot Basal lamina Capillary lumen Inter-neuron Endothelial cells Pericyte Astrocyte end-foot Basal lamina Capillary lumen Inter-neuron Fig. 1. Brain capillary endothelial cells constitute the core of the BBB. The endothelial cells are surrounded by a tubular sheath of astrocyte end-feet. Pericytes are embedded in the basal lamina (between the endothelium and the astrocyte end-feet). Reprinted from [Pottiez et al., 2009a], with permission from Elsevier). www.intechopen.com