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 (∼1000Ωcm) 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.

Kinetics of mRNA delivery and protein translation in dendritic cells using lipid-coated PLGA nanoparticles

“…Chitosan-PLGA NPs were prepared according to [ 28 , 29 ]. Briefly, 0.2% (w/v) of chitosan solution was prepared by dissolving Protasan UP CL 113 (FMC Biopolymer AS NovaMatrix, Sandvika, Norway) in a 2% (w/v) PVA solution.…”

Chitosan Nanocomplexes for the Delivery of ENaC Antisense Oligonucleotides to Airway Epithelial Cells

“…It was reported that CFBE41o-cells do not display an amiloride-sensitive current even after treatment with dexamethasone, suggesting that ENaC stays absent from the cell surface [51]. Furthermore, these cells do not generate a proper mucus when cultivated as ALI cultures [52]. Therefore, even though dysregulated mucociliary clearance is observed more proximally in the CF lung, the distal lung epithelial cell line, NCI-H441, was chosen and cultivated as ALI culture for in vitro transfection experiments, as these cells express sufficient α-ENaC for knockdown purposes [53].…”

In vivo treatment of experimental neurocysticercosis with praziquantel nanosuspensions—a metabolic approach

“…En muchos casos el objetivo de desarrollar este tipo de sistemas, es modular la liberación de fármacos en el tiempo, haciéndola más lenta y controlada 27,28 . Dentro de la gran variedad de nanovectores que han sido desarrollados en las últimas décadas (como micelas [30][31][32][33][34] , liposomas [35][36][37][38] ), uno de los más interesantes, desde el punto de vista fisicoquímico y biológico, son las nanocápsulas lipídicas sólidas (NCLs) 34 . Las…”

“…Estas NCLs se obtienen por un método de emulsificación de baja energía y se puede formular en ausencia de disolvente orgánico y con excipientes reconocidos como seguros 27 . Por otra parte, estudios previos demostraron su capacidad para aumentar la biodisponibilidad oral de diversos fármacos 34,40 , lo que puede explicarse por una mayor estabilidad gastrointestinal de las partículas respecto al fármaco sólo 41…”

“…En este sentido es importante destacar que las NPs mencionadas presentaron valores de (ver Tabla 3.5)positivos y algo más elevados que el resto de los nanosistemas estudiados.Los cultivos de células Caco-2, en las condiciones estudiadas, mostraron altos valores de TEER luego de solo 5 días posteriores a ser sembradas en los Transwells®. Los valores TEER se estabilizaron después del día 8 en un valor cercano a 1400 Ω cm 2 , lo que indica que la barrera epitelial se encuentra en óptimas condiciones.Estudios anteriores sugirieron la formación de uniones estrechas funcionales pocos días después de la siembra de células en membranas Transwells®33,34 , en este caso el cultivo de Caco-2 observó propiedades bioeléctricas equivalentes a las que se habían descrito.…”