title: Monolayers of porcine alveolar epithelial cells in primary culture as an in vitro model for drug absorption studies.
abstract: Filter-grown monolayers of porcine alveolar epithelial cells (pAEpC) in primary culture have been characterized as an in vitro model for pulmonary absorption screening of xenobiotics, including substrates of efflux systems. Experimental conditions and a protocol for transport experiments were optimized using transepithelial electrical resistances (TEER) and permeability of marker compounds as acceptance criteria. Since new drugs often feature poor water solubility, monolayer integrity in the presence of a solubilizer (dimethyl sulfoxide) was tested. Transport studies were carried out with budesonide and triamcinolone acetonide, i.e., two drugs commonly administered to the lungs. Furthermore, expression of P-glycoprotein (P-gp) was assessed by immunofluorescence microscopy and transport studies employing the substrates rhodamine 123 and digoxin. Hydrocortisone-supplemented (0.5 microg/ml) small airway basal medium as transport buffer and a maximal solubilizer concentration of 1.5% dimethyl sulfoxide were found to provide suitable conditions for drug transport studies across pAEpC, as reflected, e.g., by a minimum TEER of 600 Omega cm(2). Permeation of marker compounds was reproducible throughout several cell preparations and proved the model successful in distinguishing between low- and high-permeable drugs. P-gp expression was confirmed by immunocytochemistry, even though transport studies revealed no polarity in transepithelial marker transport. In conclusion, our results demonstrate that filter-grown monolayers of pAEpC can be used to study drug transport across alveolar epithelial barrier and thus, may represent a suitable in vitro model for pulmonary drug absorption and delivery.
authors.affiliation: Across Barriers GmbH, Science Park Saar, Saarbrücken, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Steimer
authors.forename: Helmut
authors.initials: H
authors.lastname: Franke
authors.forename: Eleonore
authors.initials: E
authors.lastname: Haltner-Ukomado
authors.forename: Michael
authors.initials: M
authors.lastname: Laue
authors.forename: Carsten
authors.initials: C
authors.lastname: Ehrhardt
authors.forename: Claus-Michael
authors.initials: CM
authors.lastname: Lehr
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000502:physiology; D000042:Absorption; D000818:Animals; D002478:Cells, Cultured; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D017097:Electric Impedance; D004847:Epithelial Cells / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D011786:Quality Control; D013552:Swine
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004121:Dimethyl Sulfoxide