An Optimized In Vitro Model of the Respiratory Tract Wall to Study Particle Cell Interactions

Abstract

As a part of the respiratory tissue barrier, lung epithelial cells play an important role against the penetration of the body by inhaled particulate foreign materials. In most cell culture models, which are designed to study particle-cell interactions, the cells are immersed in medium. This does not reflect the physiological condition of lung epithelial cells which are exposed to air, separated from it only by a very thin liquid lining layer with a surfactant film at the air-liquid interface. In this study, A549 epithelial cells were grown on microporous membranes in a two chamber system. After the formation of a confluent monolayer the cells were exposed to air. The morphology of the cells and the expression of tight junction proteins were studied with confocal laser scanning and transmission electron microscopy. Air-exposed cells maintained monolayer structure for 2 days, expressed tight junctions and developed transepithelial electrical resistance. Surfactant was produced and released at the apical side of the air-exposed epithelial cells. In order to study particle-cell interactions fluorescent 1 microm polystyrene particles were sprayed over the epithelial surface. After 4 h, 8.8% of particles were found inside the epithelium. This fraction increased to 38% after 24 h. During all observations, particles were always found in the cells but never between them. In this study, we present an in vitro model of the respiratory tract wall consisting of air-exposed lung epithelial cells covered by a liquid lining layer with a surfactant film to study particle-cell interactions.

Fate of Cellulose Nanocrystal Aerosols Deposited on the Lung Cell Surface In Vitro

“…This results in the formation of multilayers, a known phenomenon during an extended culturing period at the air−liquid interface (>24 h postexposure; Figure 2 and Supporting Information, Figure 4). 45 The confocal images in Figure 2 show the distribution of the CNCs deposited, via the ALICE, after nebulization. Individual fibers cannot be spatially resolved due to the resolution limit of sub-100 nm objects, only fiber bundles/aggregates are visible by LSM.…”

“…Exposure in the "Air Liquid Interface Cell Exposure System" (ALICE). All in vitro experiments were performed with a coculture model of the epithelial airway barrier of the human lung, 45,46 as detailed by Lehmann et al 47 Additionally, the selection of CD14 + cells was employed, as further described by Steiner et al 48 The aerosolization of nanoparticles with the ALICE system was previously published 41 and recently applied to HARN with the example of unmodified CNCs.…”

Aerosol Delivery of Functionalized Gold Nanoparticles Target and Activate Dendritic Cells in a 3D Lung Cellular Model

“…Cocultures were prepared as previously described. 15,49 Briefly, adenocarcinoma human alveolar basal epithelial cells (A549 cells) were grown under submerged conditions for 5 days on cell culture inserts (surface area of 4.2 cm 2 , pores with 3.0 μm diameter, high pore density PET membranes for six-well plates (BD Biosciences, Basel, Switzerland; 353502) at a density of 1 × 10 6 cells/mL). Monocytes were isolated from human buffy coat from healthy volunteers (Blood Donation Service, Bern University Hospital, Bern, Switzerland) by gradient centrifugation (Lymphoprep, Axis Scield, Oslo, Norway) as previously described by Blank et al 9 and Fytianos et al 13 Monocytes were differentiated into MDDCs by adding 10 ng/mL granulocyte−monocyte−colony stimulating factor and 10 ng/mL IL-4.…”

The bio-nano-interface in predicting nanoparticle fate and behaviour in living organisms: towards grouping and categorising nanomaterials and ensuring nanosafety by design

“…It has been shown that nanoparticle translocation into capillaries leads to their translocation into other organs [60][61][62][63][64][65], and evidence is emerging that the route of entry, and the biomolecules that form the initial corona at the site of entry (e.g., plasma proteins following injections versus lung surfactant proteins following inhalation), play a distinct role in determining the organ biodistribution of nanoparticles [66]. For example, accumulation of TiO 2 nanoparticles in the brain was 100-fold higher for particles entering via lung than for those injected directly into the bloodstream (Personnal Communication W.G.…”