title: Evaluation of layers of the rat airway epithelial cell line RL-65 for permeability screening of inhaled drug candidates.
abstract: A rat respiratory epithelial cell culture system for in vitro prediction of drug pulmonary absorption is currently lacking. Such a model may however enhance the understanding of interspecies differences in inhaled drug pharmacokinetics by filling the gap between human in vitro and rat in/ex vivo drug permeability screens. The rat airway epithelial cell line RL-65 was cultured on Transwell inserts for up to 21 days at an air-liquid (AL) interface and cell layers were evaluated for their suitability as a drug permeability measurement tool. These layers were found to be morphologically representative of the bronchial/bronchiolar epithelium when cultured for 8 days in a defined serum-free medium. In addition, RL-65 layers developed epithelial barrier properties with a transepithelial electrical resistance (TEER) >300 Ω cm(2) and apparent (14)C-mannitol permeability (P(app)) values between 0.5-3.0 × 10(-6)cm/s; i.e., in the same range as established in vitro human bronchial epithelial absorption models. Expression of P-glycoprotein was confirmed by gene analysis and immunohistochemistry. Nevertheless, no vectorial transport of the established substrates (3)H-digoxin and Rhodamine123 was observed across the layers. Although preliminary, this study shows RL-65 cell layers have the potential to become a useful in vitro screening tool in the pre-clinical development of inhaled drug candidates.
authors: Division of Drug Delivery and Tissue Engineering, School of Pharmacy, University of Nottingham, UK.
authors: V
authors: V
authors: Hutter
authors: C
authors: C
authors: Hilgendorf
authors: A
authors: A
authors: Cooper
authors: V
authors: V
authors: Zann
authors: D I
authors: DI
authors: Pritchard
authors: C
authors: C
authors: Bosquillon
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001980:Bronchi / Q000166:cytology; D002460:Cell Line / Q000166:cytology / Q000378:metabolism*; D002463:Cell Membrane Permeability; D004077:Digoxin / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D008353:Mannitol / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000235:genetics; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D004364:Pharmaceutical Preparations / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020112:Rhodamine 123 / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D026901:Membrane Transport Proteins; D004364:Pharmaceutical Preparations; D012333:RNA, Messenger; D020112:Rhodamine 123; D008353:Mannitol; D004077:Digoxin