Genotoxicity of nanosized Titanium dioxide particles in 16HBE14o-cells

Bronchial and alveolar cells are both targets for granular dusts and fibers up to an aerodynamic size of 10 μm. In the first phase of NANOGENOTOX partners performed an exploratory investigation of the sensitivity of different lung cell lines against polydispersed manufactured nanomaterials (MNs). BfR was in charge of the assessment of the potential genotoxicty for different types of titanium dioxide (TiO2) in transformed with SV40 large T-antigen replication origin deficient human bronchial epithelial cells (16HBE14o- cells). HBE cells widely and rapidly accumulate TiO2 as aggregates in cytosolic vesicles. Interestingly, intracellular nanomaterials accumulation is assumed to be dissociated from cytotoxicity (Belade et al., 2012). In this study we performed cytotoxicity analysis using impedance analysis and comet assay following exposure to different forms of TiO2 nanomaterials (NM102-NM105) at different doses for 3 h and 24 h. Two experiments were performed for each TiO2 MN. Cytotoxicity was only evident at the highest dose. However, indications for DNA damage were not observed at any dose. A dose-response relationship for MMS as positive chemical control was established for the parameters % DNA in tail and Olive tail moment. The level of DNA damage obtained with the positive control chemical MMS (22 μg/ml) was always clearly increased at the 3-h and 24-h exposure. Nanomaterials exposure was performed according to the NANOGENOTOX dispersion protocol using ultrasonication of test-item stock solutions. Particle size distribution in dilutions of exposure medium was followed by dynamic light scattering. Particle size distribution changes considerably with dose. Only the lowest dose (2 μg/ml) shows nanoparticles according to the ISO definition. HBE cells appear not to be the most sensitive cell line to investigate the potential genotoxicity of nanomaterials. Future work in NANOGENOTOX therefore selected the more sensitive cell line BEAS 2B instead.