title: Modelling the bronchial barrier in pulmonary drug delivery: A human bronchial epithelial cell line supplemented with human tracheal mucus.
abstract: The airway epithelium together with the mucus layer coating it forms a protective system that efficiently filters and removes potentially harmful particles contained in inhaled air. The same mechanism, however, serves to entrap particulate drug carriers, precluding their interaction with their target. The mucus barrier is often neglected in in vitro testing setups employed for the assessment of pulmonary drug delivery strategies. Therefore, our aim was to more accurately model the bronchial barrier, by developing an in vitro system comprising a tight epithelial cell layer which may be optionally supplemented with a layer of human tracheal mucus. To form the epithelium in vitro, we used the cystic fibrosis cell line CFBE41o-, which can be grown as monolayers on Transwell® supports, expressing tight junctions as well as relevant transport proteins. In contrast to the cell line Calu-3, however, CFBE41o- does not produce mucus. Therefore, native human mucus, obtained from tracheal tubes of patients undergoing elective surgery, was used as a supplement. The compatibility of CFBE41o- cells with the human mucus was addressed with the MTT assay, and confirmed by fluorescein diacetate/propidium iodide live/dead staining. Moreover, the CFBE41o- cells retained their epithelial barrier properties after being supplemented with mucus, as evidenced by the high trans-epithelial electrical resistance values (∼1000Ωcm2) together with a continued low level of paracellular transport of sodium fluorescein. Fluorescently-labeled chitosan-coated PLGA nanoparticles (NP, ∼168nm) were used as a model drug delivery system to evaluate the suitability of this in vitro model for studying mucus permeation and cell uptake. Comparing CFBE41o- cell monolayers with and without mucus, resp., showed that the NP uptake was dramatically reduced in the presence of mucus. This model may therefore be used as a tool to study potential mucus interactions of aerosolized drugs, and more specifically NP-based drug delivery systems designed to exert their effect in the bronchial region.
authors.affiliation: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Xabi
authors.initials: X
authors.lastname: Murgia
authors.affiliation: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Hanzey
authors.initials: H
authors.lastname: Yasar
authors.affiliation: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Cristiane
authors.initials: C
authors.lastname: Carvalho-Wodarz
authors.affiliation: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Brigitta
authors.initials: B
authors.lastname: Loretz
authors.affiliation: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gordon
authors.affiliation: Department of Anesthesia and Intensive Care, Klinikum Saarbrücken, 66119 Saarbrücken, Germany.
authors.forename: Konrad
authors.initials: K
authors.lastname: Schwarzkopf
authors.affiliation: Biopharmaceutics and Pharmaceutical Technology, Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schaefer
authors.affiliation: Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarland University, 66123 Saarbrücken, Germany; Biopharmaceutics and Pharmaceutical Technology, Department of Pharmacy, Saarland University, 66123 Saarbrücken, Germany. Electronic address: claus-michael.lehr@helmholtz-hzi.de.
authors.forename: Claus-Michael
authors.initials: CM
authors.lastname: Lehr
mesh_terms: D000336:Aerosols; D001980:Bronchi / Q000166:cytology / Q000378:metabolism*; D018929:Cell Culture Techniques / Q000379:methods*; D002460:Cell Line; D002463:Cell Membrane Permeability; D048271:Chitosan / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000008:administration & dosage / Q000737:chemistry; D004337:Drug Carriers / Q000737:chemistry; D017097:Electric Impedance; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005260:Female; D019793:Fluorescein / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005612:Freeze Drying; D006801:Humans; D008297:Male; D008875:Middle Aged; D009093:Mucus / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry; D010539:Permeability; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*
chemical_list: D000336:Aerosols; D020099:Coated Materials, Biocompatible; D004337:Drug Carriers; D048271:Chitosan; D019793:Fluorescein
keywords: Cystic fibrosis; Epithelial drug delivery; Nanoparticles; Pulmonary mucus