Modular air-liquid interface aerosol exposure system (MALIES) to study toxicity of nanoparticle aerosols in...

We present a novel lung aerosol exposure system named MALIES (modular air-liquid interface exposure system), which allows three-dimensional cultivation of lung epithelial cells in alveolar-like scaffolds (MatriGrids^®) and exposure to nanoparticle aerosols. MALIES consists of multiple modular units for aerosol generation, and can be rapidly assembled and commissioned. The MALIES system was proven for its ability to reliably produce a dose-dependent toxicity in A549 cells using CuSO₄ aerosol. Cytotoxic effects of BaSO₄- and TiO₂-nanoparticles were investigated using MALIES with the human lung tumor cell line A549 cultured at the air-liquid interface. Experiments with concentrations of up to 5.93 × 10⁵ (BaSO₄) and 1.49 × 10⁶ (TiO₂) particles/cm³, resulting in deposited masses of up to 26.6 and 74.0 µg/cm² were performed using two identical aerosol exposure systems in two different laboratories. LDH, resazurin reduction and total glutathione were measured. A549 cells grown on MatriGrids^® form a ZO-1- and E-Cadherin-positive epithelial barrier and produce mucin and surfactant protein. BaSO₄-NP in a deposited mass of up to 26.6 µg/cm² resulted in mild, reversible damage (~ 10% decrease in viability) to lung epithelium 24 h after exposure. TiO₂-NP in a deposited mass of up to 74.0 µg/cm² did not induce any cytotoxicity in A549 cells 24 h and 72 h after exposure, with the exception of a 1.7 fold increase in the low exposure group in laboratory 1. These results are consistent with previous studies showing no significant damage to lung epithelium by short-term treatment with low concentrations of nanoscale BaSO₄ and TiO₂ in in vitro experiments.