Properties of an immortalised vascular endothelial/glioma cell co-culture model of the blood-brain barrier.

In an effort to obtain a useful in vitro model possessing some of the properties of the blood-brain barrier, we have investigated the properties and interactions of immortalized cell lines. Immortalised human umbilical vein endothelial cells (HUVEC-304), in co-culture with rat C6 glioma cells in a two-chambered assembly, form tight junctional complexes, and develop a permeability barrier having a high transcellular electrical resistance. The endothelial cells generate a barrier with greatest integrity in the presence of glioma cells, or in the presence of glioma cell conditioned medium. Under these conditions, the endothelial cells also display pronounced structural changes which do not occur in the absence of glioma cells. Morphological alterations include a flattening of cell shape from a cuboidal-type to a squamous-type of appearance, and a re-organization of F-actin microfilaments. The integrity of the barrier can be reversibly disrupted by osmotic shock or by tumor necrosis factor-alpha (TNF-alpha). We interpret these observations to indicate that co-cultures of immortalized vascular endothelial and C6 glioma cells provide a model for the investigation of cell-cell interactions required for the generation of a barrier having several properties of the blood-brain barrier.