, 2008, Deli et al., 2005 and Tóth et al., 2011). The key features of the adult BBB result from a sequence of cell:cell Baf-A1 mw interactions during development between the ingrowing vessel sprouts and the associated cells of the NVU (Liebner et al., 2011). When brain microvessels are isolated from adult mammalian brain and brain endothelial cells are cultured from these vessel fragments, they retain many key features of the BBB phe-notype. In 1969, Siakotos and colleagues described for the first

time a method to successfully isolate bovine and human brain endothelial cells (Siakotos et al., 1969). Nearly a decade later, Panula et al. demonstrated the migration of rat brain endothelial cells from isolated capillaries. These cells were able to grow in culture and had strong alkaline phosphatase activity (Panula et al., 1978). Tontsch and Bauer (1989) simplified the culture methods for isolating murine and porcine brain endothelial cells (e.g. avoiding sieving steps, gradient centrifugations) and optimised the culture medium to increase cell yield. They also found that when proliferative factors such as endothelial cell growth supplement (ECGS) and heparin were removed from culture medium, the morphology of cells changed from spindle-shape to cobblestone phenotype. Through a series of experiments, DeBault and Cancilla gave evidence for the influence of

astrocytic factors on BBB phenotype of brain endothelial cells (DeBault and Cancilla, 1980a, DeBault and Cancilla, 1980b and DeBault, 1981). These studies led to the development of co-culture models of the BBB (Joó, see more 1985). We chose to develop a porcine BBB model for several reasons: (1) A single pig brain gives a high yield of cells compared to that from rat or mouse. (2) Porcine brains are relatively easy to obtain as they are

a by-product of the meat industry; there is no need to have animal breeding facilities 17-DMAG (Alvespimycin) HCl on site to maintain a continuous supply of brain tissue. (3) Porcine brain endothelial cells (PBECs) generally retain many key features of the BBB following isolation, and the rate of loss of BBB phenotype in culture is less than for rodent or bovine BBB models (Deli et al., 2005), therefore co-culture with astrocytes is not essential to induce functional expression of tight junctions (i.e. high TEER) (Patabendige et al., this issue). (4) The porcine genome, anatomy, physiology and disease progression reflect human biology more closely than many established laboratory animals (Walters et al., 2011). (5) The availability of miniature pigs and novel porcine transgenic disease models make the pig the most suitable animal model to study human disease (Bendixen et al., 2010 and Lunney, 2007). The miniature pig is now a well established ‘large’ mammalian model for pharmacokinetics/toxicology studies (Bode et al., 2010) and is also used for surgical studies to generate organs for xenotransplantation (Vodicka et al., 2005).