Cellular Effects in an <i>In Vitro</i> Human 3D Cellular Airway Model and A549/BEAS-2B <i>In Vitro</i> Cell Cultures Following Air Exposure to Cerium Oxide Particles at an Air–Liquid Interface

Abstract

There is a need for representative in vitro models to assess the effects of airborne particles on lung health. The objective of this study was to assess the cellular effects of cerium oxide (CeO2) particles exposed via an air–liquid interface in three relevant cell models in parallel. BEAS-2B, A549, and MucilAir™ cells were exposed for 1 hour to CeO2 particles comprising a range of doses (0.04–3.0 μg/cm2) and sizes (0.75 μm and 13.8 nm primary particle size). MucilAir cells are complex 3D cell systems with intact mucocilairy system and are cultured at air–liquid interface, in contrast to the simple cell lines A549 and BEAS 2B, which are essentially immersion models. Cell responses varied according to cell type used. BEAS-2B and A549 cells (normally cultured in liquid media) were sensitive to air exposure alone and exposure to CeO2 particles in terms of cytotoxicity, inflammation, and genotoxicity. MucilAir cells normally cultured at an air–liquid interface were insensitive to the air stream alone and only exhibited oxidative stress response after exposure to CeO2 particles. Minimal or no effects on gene expression were detected in all cell types. Variations according to different sizes and doses of CeO2 were apparent but did not result in any definitive patterns. The minimal effects, except for the oxidative stress response, observed in the MucilAir cells are likely because of the presence of extracellular defensive mechanisms, such as intact mucocilairy system, that were not present in the other cell types. Further studies with MucilAir cells and other compounds are warranted to understand wider applicability in inhalation toxicology research.