Evaluation of an in vitro coculture model for the blood-brain barrier: Comparison of human umbilical vein endothelial cells (ECV304) and rat glioma cells (C6) from two commercial sources

Cocultures of human umbilical vein endothelial cells (ECV304) and rat gliom a cells (C6) from two commercial sources. American Type Culture Collection and European Collection of Animal Cell Cultures, were evaluated as an in vi tro model for the blood-brain barrier, Monolayers of endothelial cells grow n in the presence or absence of glial cells rc ere examined for transendoth elial electrical resistance, sucrose permeability, morphology, multidrug re sistance-associated protein expression, and P-glycoprotein expression and f unction. Coculture of glial cells with endothelial cells increased electric al resistance and decreased sucrose permeability across European endothelia l. cell monolayers, but had no effect on American endothelial cells. Cocult ure of European glial cells with endothelial cells caused cell flattening a nd decreased cell stacking with both European and American endothelial cell s. No P-glycoprotein or multidrug resistance-associated protein was immunod etected in endothelial cells grown in glial cell-conditioned medium. Functi onal P-glycoprotein was demonstrated in American endothelial cells selected in vinblastine-containing medium over eight passages, but these cells did not form a tight endothelium, In conclusion, while European glial cells con fer blood-brain barrier-like morphology and barrier integrity to European e ndothelial cells in coculture, the European endothelial-glial cell cocultur e model does not express P-glycoprotein, normally found at the blood-brain barrier Further. the response of endothelial cells to glial factors was dep endent on cell source, implying heterogeneity among cell populations. On th e basis of these observations, the umbilical vein endothelial cell-glial ce ll coculture model does not appear to be a viable model for predicting bloo d-brain barrier penetration of drug molecules.