HYPOTHALAMIC EXTRACT INFLUENCES A BLOOD-BRAIN-BARRIER MODEL OF PORCINE BRAIN CAPILLARY ENDOTHELIAL-CELLS

The purpose of this study was to investigate the influence of hypothal amic extract, astrocyte coculture, and astrocyte-conditioned medium on the barrier function of an in vitro model of the blood-brain barrier. Porcine brain capillary endothelial cells were grown on polycarbonate membranes suspended between two chambers of media, representing the c apillary lumen and brain interstitium. Endothelial cells grown alone a nd cocultured with astrocytes were cultured in growth medium with or w ithout 50 mu g/mL hypothalamic extract. An additional treatment consis ted of endothelial cells cultured in growth medium that was first cond itioned by astrocytes. Coculture consisted of a noncontact model with astrocytes attached to the bottom of the abluminal chamber. Barrier fu nction of the endothelial cells was tested on days 1 through 9 post-se eding by measuring permeability to macromolecules (albumin) and small ions (electrical resistance). Resistance to the passage of macromolecu les and small ions was greatest for endothelial cells grown without as trocytes in growth medium supplemented with hypothalamic extract. This barrier was maximal during days 4 through 7 post-seeding and was sign ificantly less permeable than the barrier formed by endothelial cells grown in un-supplemented growth medium, in coculture with astrocytes, or in astrocyte-conditioned medium. These results demonstrate that a n oncontact coculture with astrocytes did not enhance the integrity of t his in vitro BBB model employing porcine brain capillary endothelial c ells, but barrier function was increased when the model's medium was s upplemented with hypothalamic extract.