The AAPS Journal

, Volume 16, Issue 5, pp 1046–1055

An Electrically Tight In Vitro Blood–Brain Barrier Model Displays Net Brain-to-Blood Efflux of Substrates for the ABC Transporters, P-gp, Bcrp and Mrp-1

  • Hans Christian Helms
  • Maria Hersom
  • Louise Borella Kuhlmann
  • Lasina Badolo
  • Carsten Uhd Nielsen
  • Birger Brodin
Research Article

DOI: 10.1208/s12248-014-9628-1

Cite this article as:
Helms, H.C., Hersom, M., Kuhlmann, L.B. et al. AAPS J (2014) 16: 1046. doi:10.1208/s12248-014-9628-1

Abstract

Efflux transporters of the ATP-binding cassette superfamily including breast cancer resistance protein (Bcrp/Abcg2), P-glycoprotein (P-gp/Abcb1) and multidrug resistance-associated proteins (Mrp’s/Abcc’s) are expressed in the blood–brain barrier (BBB). The aim of this study was to investigate if a bovine endothelial/rat astrocyte in vitro BBB co-culture model displayed polarized transport of known efflux transporter substrates. The co-culture model displayed low mannitol permeabilities of 0.95 ± 0.1 · 10−6 cm·s−1 and high transendothelial electrical resistances of 1,177 ± 101 Ω·cm2. Bidirectional transport studies with 3H-digoxin, 3H-estrone-3-sulphate and 3H-etoposide revealed polarized transport favouring the brain-to-blood direction for all substrates. Steady state efflux ratios of 2.5 ± 0.2 for digoxin, 4.4 ± 0.5 for estrone-3-sulphate and 2.4 ± 0.1 for etoposide were observed. These were reduced to 1.1 ± 0.08, 1.4 ± 0.2 and 1.5 ± 0.1, by addition of verapamil (digoxin), Ko143 (estrone-3-sulphate) or zosuquidar + reversan (etoposide), respectively. Brain-to-blood permeability of all substrates was investigated in the presence of the efflux transporter inhibitors verapamil, Ko143, zosuquidar, reversan and MK 571 alone or in combinations. Digoxin was mainly transported via P-gp, estrone-3-sulphate via Bcrp and Mrp’s and etoposide via P-gp and Mrp’s. The expression of P-gp, Bcrp and Mrp-1 was confirmed using immunocytochemistry. The findings indicate that P-gp, Bcrp and at least one isoform of Mrp are functionally expressed in our bovine/rat co-culture model and that the model is suitable for investigations of small molecule transport.

KEY WORDS

blood–brain barrierbreast cancer resistance proteinmultidrug resistance-associated proteinp-glycoproteinpolarized small molecule transport

Copyright information

© American Association of Pharmaceutical Scientists 2014

Authors and Affiliations

  • Hans Christian Helms
    • 1
  • Maria Hersom
    • 1
  • Louise Borella Kuhlmann
    • 1
  • Lasina Badolo
    • 2
  • Carsten Uhd Nielsen
    • 1
  • Birger Brodin
    • 1
  1. 1.Department of Pharmacy, The Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
  2. 2.ValbyDenmark