Dry Generation of CeO2 Nanoparticles and Deposition onto a Co-Culture of A549 and THP-1 Cells in Air-Liquid Interface-Dosimetry Considerations and Comparison to Submerged Exposure.

Francesca Cappellini,Venkatanaidu Karri,Karine Elihn,Per Gerde,Maria Malmlöf,Inger Odnevall Wallinder,Sebastiano Di Bucchianico,Hanna L Karlsson,Maria Kippler,Jonas Hedberg,Siiri Latvala

doi:10.3390/nano10040618

Abstract

Relevant in vitro assays that can simulate exposure to nanoparticles (NPs) via inhalation are urgently needed. Presently, the most common method employed is to expose lung cells under submerged conditions, but the cellular responses to NPs under such conditions might differ from those observed at the more physiological air-liquid interface (ALI). The aim of this study was to investigate the cytotoxic and inflammatory potential of CeO2 NPs (NM-212) in a co-culture of A549 lung epithelial cells and differentiated THP-1 cells in both ALI and submerged conditions. Cellular dose was examined quantitatively using inductively coupled plasma mass spectrometry (ICP-MS). The role of serum and LPS-priming for IL-1β release was further tested in THP-1 cells in submerged exposure. An aerosol of CeO2 NPs was generated by using the PreciseInhale® system, and NPs were deposited on the co-culture using XposeALI®. No or minor cytotoxicity and no increased release of inflammatory cytokines (IL-1β, IL-6, TNFα, MCP-1) were observed after exposure of the co-culture in ALI (max 5 µg/cm2) or submerged (max 22 µg/cm2) conditions. In contrast, CeO2 NPs cause clear IL-1β release in monocultures of macrophage-like THP-1, independent of the presence of serum and LPS-priming. This study demonstrates a useful approach for comparing effects at various in-vitro conditions.

Highlights

The production and use of different nanoparticles (NPs) is steadily increasing in society, leading to an urgent need for reliable assessment of their toxicological properties
Under submerged conditions, NPs may be attached to the wall of the cell exposure plate, and can remain in the liquid, and never reach the cells [1,2,5,6]
Several air-liquid interface (ALI) systems have been described in the literature using different methods for aerosol generation and types of cell exposure units [7,8,9]

Summary

Introduction

The production and use of different nanoparticles (NPs) is steadily increasing in society, leading to an urgent need for reliable assessment of their toxicological properties. Most in vitro studies applied today use lung cells exposed to particles in a liquid suspension, i.e., submerged exposures. Such exposure leads to interactions between the medium and the NPs, often resulting in agglomeration, corona formation, dissolution etc. A more realistic scenario for assessing lung cell toxicity is to use direct exposure of the cells in the air-liquid interface (ALI). In this case, the cells are cultured on inserts with no cell media covering the cells, which enables exposure of the cells to an aerosol of particles. There are, many challenges with ALI systems, including difficulties generating dry nano-aerosols from powders and depositing these on the cells

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