Astrocytes increase the functional expression of P-glycoprotein in an in vitro model of the blood-brain barrier

• Published in: Pharmaceutical research 2000-10, Vol.17 (10), p.1198-1205
• Main Authors: GAILLARD, Pieter Jaap, VAN DER SANDT, Inez Cornelia, VOORWINDEN, Levina Helena, VU, Dung, NIELSEN, Jette Lyngholm, DE BOER, Albertus Gerrit, BREIMER, Douwe Durk
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic agents; Antineoplastic Agents, Phytogenic - pharmacokinetics; Astrocytes - cytology; Astrocytes - physiology; ATP Binding Cassette Transporter, Subfamily B, Member 1 - biosynthesis; ATP Binding Cassette Transporter, Subfamily B, Member 1 - genetics; ATP Binding Cassette Transporter, Subfamily B, Member 1 - physiology; Biological and medical sciences; Blood-Brain Barrier - physiology; Brain - blood supply; Caco-2 Cells - metabolism; Capillaries - cytology; Capillaries - metabolism; Cattle; Cell physiology; Coculture Techniques; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Fluorescent Dyes - pharmacokinetics; Fundamental and applied biological sciences. Psychology; General aspects; Humans; Medical sciences; Membrane and intracellular transports; Molecular and cellular biology; Pharmacology. Drug treatments; Rhodamine 123 - pharmacokinetics; Transfection; Vinblastine - pharmacokinetics
• ISSN: 0724-8741; 1573-904X
• DOI: 10.1023/A:1026406528530

To investigate the influence of astrocytes on P-glycoprotein (Pgp) expression and intracellular accumulation of Pgp substrates, separate from their net transcellular transport across the blood-brain barrier (BBB). An in vitro BBB model was used, comprising of brain capillary endothelial cells (BCEC) monolayers or BCEC co-cultured with astrocytes. BCEC+astrocyte co-cultures seemed to express a higher level of Pgp compared to BCEC monolayers. Inhibition of Pgp results in an increased intracellular accumulation of Pgp substrates in both BCEC monolayers and BCEC+astrocyte co-cultures, and increased the sensitivity for vinblastine mediated disruption of the in vitro BBB (called the vinblastine exclusion assay). BCEC monolayers were more sensitive to vinblastine mediated disruption compared to BCEC+astrocyte co-cultures. In the latter, but not in BCEC monolayers, an inhibitable polar transport of Pgp substrates was only found from the brain to the blood side of the filter. Astrocytes increase the functional expression of Pgp in our in vitro BBB model. These results also illustrate that an important role for Pgp on the BBB is to protect the barrier against intracellular accumulation of cytotoxic BBB disrupting compounds.