Cellular responses of lung cells cultured at an Air-liquid Interface are influenced by spatial nanoparticle deposition patterns in an in vitro aerosol exposure system.

The deposition of inhaled particles is typically highly localized in both the bronchial and alveolar region of the lung displaying spot-like, line-like and other deposition patterns. However, knowledge is very limited on how different deposition patterns may influence downstream cellular responses. In this study, the Dosimetric Aerosol in Vitro Inhalation Device (DAVID) was used for dose-controlled deposition of cupric oxide nanoparticles (CuONPs) in four different patterns (i.e., spot, ring, line and circle) on human alveolar A549 cells cultured at an air-liquid interface (ALI). After CuONP deposition (<15 min) and a 24 h incubation phase, cell viability, apoptotic / necrotic cell count, and gene expressions were measured. At the lowest dose of ~5 μg/cm2, the line pattern resulted in the lowest viability of cells (57%), followed by the spot pattern (85%) while the ring and circle patterns exhibited >90% viability, compared to the particle free air control. At the highest dose of ~20 μg/cm2, the viability reduced to 44%-60% for all patterns. Also, the gene profile was found to depend on deposition pattern. The results demonstrate that the deposition pattern is a critical parameter influencing cellular response, thus an important parameter to consider in toxicity and drug delivery studies. Furthermore, the ability of DAVID to control the delivery of aerosolized particles in various deposition patterns was demonstrated, which enables implementation of nonhomogeneous particle deposition patterns that mimic real-life human inhalation exposures in future in vitro toxicology studies.