Use of EpiAlveolar Lung Model to Predict Fibrotic Potential of Multi-Walled Carbon Nanotubes.

Expansion in production and commercial use of nanomaterials increases the potential human exposure during the lifecycle of these materials (production, use, and disposal). Inhalation is a primary route of exposure to nanomaterials, therefore it is critical to assess their potential respiratory hazard. Herein, we developed a three dimensional alveolar model (EpiAlveolarTM) consisting of human primary alveolar epithelial cells, fibroblasts, and endothelial cells, with or without macrophages for predicting long-term responses to aerosols. Following thorough characterization of the model, (pro-)inflammatory and (pro-)fibrotic responses based on the adverse outcome pathway concept for lung fibrosis were assessed upon repeated sub-chronic exposures (up to 21 days) to two types of multi-walled carbon nanotubes (MWCNTs), and silica quartz particles. We simulate occupational exposure doses for the MWCNTs (1 - 30 μg/cm2) using an air-liquid interface exposure device (VITROCELL® Cloud) with repeated exposures over 3 weeks. Specific key events leading to the lung fibrosis, such as barrier integrity, release of (pro-)inflammatory, and (pro-)fibrotic markers show the responsiveness of the model. Nanocyl induced, in general, a less pronounced reaction than Mitsui-7, and the cultures with human monocyte-derived macrophages (MDMs) showed the (pro-)inflammatory response at later time-points than without MDMs. In conclusion, we present a robust alveolar model to predict inflammatory and fibrotic responses upon exposure to MWCNTs.