title: In vitro porcine blood-brain barrier model for permeability studies: pCEL-X software pKa(FLUX) method for aqueous boundary layer correction and detailed data analysis.
abstract: In vitro blood-brain barrier (BBB) models from primary brain endothelial cells can closely resemble the in vivo BBB, offering valuable models to assay BBB functions and to screen potential central nervous system drugs. We have recently developed an in vitro BBB model using primary porcine brain endothelial cells. The model shows expression of tight junction proteins and high transendothelial electrical resistance, evidence for a restrictive paracellular pathway. Validation studies using small drug-like compounds demonstrated functional uptake and efflux transporters, showing the suitability of the model to assay drug permeability. However, one limitation of in vitro model permeability measurement is the presence of the aqueous boundary layer (ABL) resulting from inefficient stirring during the permeability assay. The ABL can be a rate-limiting step in permeation, particularly for lipophilic compounds, causing underestimation of the permeability. If the ABL effect is ignored, the permeability measured in vitro will not reflect the permeability in vivo. To address the issue, we explored the combination of in vitro permeability measurement using our porcine model with the pKa(FLUX) method in pCEL-X software to correct for the ABL effect and allow a detailed analysis of in vitro (transendothelial) permeability data, Papp. Published Papp using porcine models generated by our group and other groups are also analyzed. From the Papp, intrinsic transcellular permeability (P0) is derived by simultaneous refinement using a weighted nonlinear regression, taking into account permeability through the ABL, paracellular permeability and filter restrictions on permeation. The in vitro P0 derived for 22 compounds (35 measurements) showed good correlation with P0 derived from in situ brain perfusion data (r(2)=0.61). The analysis also gave evidence for carrier-mediated uptake of naloxone, propranolol and vinblastine. The combination of the in vitro porcine model and the software analysis provides a useful tool to better predict BBB permeability in vivo and gain better mechanistic information about BBB permeation.
authors.affiliation: King's College London, Institute of Pharmaceutical Science, Franklin Wilkins Building, 150 Stamford St., London SE1 9NH, UK; HICoE Centre for Drug Research, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia; Center for Neuroscience Services and Research, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
authors.forename: Siti R
authors.initials: SR
authors.lastname: Yusof
authors.affiliation: in-ADME Research, 1732 First Ave., #102, New York, NY 10128, USA.
authors.forename: Alex
authors.initials: A
authors.lastname: Avdeef
authors.affiliation: King's College London, Institute of Pharmaceutical Science, Franklin Wilkins Building, 150 Stamford St., London SE1 9NH, UK. Electronic address: joan.abbott@kcl.ac.uk.
authors.forename: N Joan
authors.initials: NJ
authors.lastname: Abbott
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001812:Blood-Brain Barrier / Q000378:metabolism*; D002199:Capillary Permeability / Q000502:physiology*; D017097:Electric Impedance; D042783:Endothelial Cells / Q000378:metabolism; D066298:In Vitro Techniques; D012984:Software; D013223:Statistics as Topic; D013552:Swine / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism
keywords: Acetylsalicylic acid (PubChem CID: 2244); Aqueous boundary layer; Blood–brain barrier; Caffeine (PubChem CID: 64136); Colchicine (PubChem CID: 6167); Dexamethasone (PubChem CID: 5743); Diazepam (PubChem CID: 3016); In vitro model; Naloxone (PubChem CID: 5284596); Permeability; Phenytoin (PubChem CID: 1775); Propranolol (PubChem CID: 62882); Vinblastine (PubChem CID: 241902); l-Leucine (PubChem CID: 6106); pCEL-X software