Optimization of an air–liquid interface exposure system for assessing toxicity of airborne nanoparticles

Abstract

The use of refined toxicological methods is currently needed for characterizing the risks of airborne nanoparticles (NPs) to human health. To mimic pulmonary exposure, we have developed an air–liquid interface (ALI) exposure system for direct deposition of airborne NPs on to lung cell cultures. Compared to traditional submerged systems, this allows more realistic exposure conditions for characterizing toxicological effects induced by airborne NPs. The purpose of this study was to investigate how the deposition of silver NPs (AgNPs) is affected by different conditions of the ALI system. Additionally, the viability and metabolic activity of A549 cells was studied following AgNP exposure. Particle deposition increased markedly with increasing aerosol flow rate and electrostatic field strength. The highest amount of deposited particles (2.2 μg cm–2) at cell‐free conditions following 2 h exposure was observed for the highest flow rate (390 ml min–1) and the strongest electrostatic field (±2 kV). This was estimated corresponding to deposition efficiency of 94%. Cell viability was not affected after 2 h exposure to clean air in the ALI system. Cells exposed to AgNPs (0.45 and 0.74 μg cm–2) showed significantly (P < 0.05) reduced metabolic activities (64 and 46%, respectively). Our study shows that the ALI exposure system can be used for generating conditions that were more realistic for in vitro exposures, which enables improved mechanistic and toxicological studies of NPs in contact with human lung cells.Copyright © 2016 The Authors Journal of Applied Toxicology Published by John Wiley & Sons Ltd.

In vitro genotoxicity of airborne Ni‐NP in air–liquid interface

“…The quantified deposition on cell‐free inserts was approximately 14–21 times higher than compared to the cell‐containing inserts. A similar observation was made in a previous study, in which the deposition of Ag‐NPs was studied in the same ALI exposure system (Latvala et al, ) and in another study with Cu‐NPs (Elihn et al, ). The difference in deposited amount of Ni‐NP at cell‐free and cell‐containing conditions may be due to evaporation of liquid from the cell surface/medium below the cells at the cell‐containing conditions, which may prevent part of the Ni‐NP deposition.…”

“…The difference in deposited amount of Ni‐NP at cell‐free and cell‐containing conditions may be due to evaporation of liquid from the cell surface/medium below the cells at the cell‐containing conditions, which may prevent part of the Ni‐NP deposition. Differences due to different quantification methods (gravimetrical vs. ICP‐MS) cannot be ruled out completely, but a previous in‐depth comparison for Ag‐NPs suggests that such a difference was rather small (Latvala et al, ). Therefore, to quantify the exposure concentrations as accurately as possible in this study, the total Ni mass was analyzed chemically from two cell culture inserts after each ALI treatment.…”

“…Based on a previous optimization study of the ALI system (Latvala et al, 2016b), aerosol flow rate of 214 ml min −1 and applied electrostatic field strength of ±1 kV were chosen for all experiments. The aerosol flow rate was controlled with a separate airflow controller (critical orifice) for each of the six exposure chambers.…”

“…The applied electrostatic field between the aerosol inlet and a metal plate underneath the exposure chambers alternated between a positive and a negative charge (±1 kV) at a frequency of 0.24 Hz and enabled deposition of NPs on cell cultures. Further details of the exposure system set-up and parameters are presented in a previous study (Latvala et al, 2016b).…”

Multi-omics analysis of ten carbon nanomaterials effects highlights cell type specific patterns of molecular regulation and adaptation

“…Combination of different OMICS methods can inform more thoroughly about ENMs MOA, which could be further used in ENM grouping approaches, as suggested by Riebeling et al (2017). Gene expression profiling of co-cultures and 3D cultures, as well as systems taking into account exposure route such as Air Liquid Interface cultures (Latvala et al, 2016;Kletting, 2017), better resemble the in vivo exposure scenarios, but before clear conclusions about the ENM MOA can be drawn, cell type-specific responses need to be addressed by omics approaches (Drasler et al, 2017;Snyder-Talkington et al, 2015). The importance of multi-omics approaches in the study of MOA of toxicants has been demonstrated in several toxicogenomics studies (Jayapal, 2012;Gavin, 2016).…”