A study to assess the ability of different in vitro exposure models to predict in vivo pulmonary adverse effects

Inhalation is a major exposure route for metallic and low soluble nanomaterials (NM), and TiO2 is one of the most used in nanotechnology products. The aim of our study is to evaluate if using more complex in vitro methods, by exposing alveolar cells at the air-liquid interface (ALI) to nano-TiO2 aerosols, gives more predictive toxicological results compared to submerged exposures to suspensions. Three different nano-TiO2 (NM105, NM101, NM100) were used. An exposure system was set up using Vitrocell® devices to expose cells at the ALI during 3h. Cells (A549 or A549+THP-1) were exposed at the ALI to aerosols or in submerged conditions to NM suspensions. Rats were exposed by intratracheal instillation. Biological activity (viability, oxidative stress and cytokines) was assessed at 24h, in vitro on cells and in vivo on bronchoalveolar lavage fluids, to perform vitro/vivo comparisons. The doses achieved using our in vitro aerosol exposure system (maximum around 3 μg/cm²) were sufficient to observe biological effects on the coculture. Generally, we observed effects at lower doses when exposing cells to aerosols compared to suspensions. In vivo experiments are ongoing. For now we observed that the NM101 seems to induce more biological adverse effect than the NM100 both in vivo and in vitro. Further comparisons between in vivo and in vitro results will be performed to assess the predictivity of the in vitro methods used. This work is supported by the French ministry of environment (“Programme 190”) and by the EU-FP7 (NANoREG project)