While new exciting applications arise from rapid development of new advanced materials, their lifecycle, from production, processing, to degradation or even combustion, may inevitably result in the release of particulate matter into the environment. [1-3] According to the Organisation for Economic Cooperation and Development (OECD) and the World Health Organization (WHO), inhalation of particulate matter, predominantly of anthropogenic origin, is associated with several million human deaths globally every year. [4-6] While larger particles, deposited in airways, can be efficiently cleared from the bronchial region by the mucociliary escalator, [7] nanomaterials, the term used here for both submicron-sized particles (at least two dimensions below 1 µm) and nanoparticles (at least one dimension below 100 nm), can reach the alveolar region. [7,8] Due to the persistency On a daily basis, people are exposed to a multitude of health-hazardous airborne particulate matter with notable deposition in the fragile alveolar region of the lungs. Hence, there is a great need for identification and prediction of material-associated diseases, currently hindered due to the lack of in-depth understanding of causal relationships, in particular between acute exposures and chronic symptoms. By applying advanced microscopies and omics to in vitro and in vivo systems, together with in silico molecular modeling, it is determined herein that the long-lasting response to a single exposure can originate from the interplay between the newly discovered nanomaterial quarantining and nanomaterial cycling between different lung cell types. This new insight finally allows prediction of the spectrum of lung inflammation associated with materials of interest using only in vitro measurements and in silico modeling, potentially relating outcomes to material properties for a large number of materials, and thus boosting safe-by-design-based material development. Because of its profound implications for animal-free predictive toxicology, this work paves the way to a more efficient and hazard-free introduction of numerous new advanced materials into our lives.

Nanoparticle toxicity assessments have moved closer to physiological conditions while trying to avoid the use of animal models. An example of new in vitro exposure techniques developed is the exposure of cultured cells at the air–liquid interface (ALI), particularly in the case of respiratory airways. While the commercially available VITROCELL® Cloud System has been applied for the delivery of aerosolized substances to adherent cells under ALI conditions, it has not yet been tested on lung surfactant and semi-adherent cells such as alveolar macrophages, which are playing a pivotal role in the nanoparticle-induced immune response. Objectives: In this work, we developed a comprehensive methodology for coating semi-adherent lung cells cultured at the ALI with aerosolized surfactant and subsequent dose-controlled exposure to nanoparticles (NPs). This protocol is optimized for subsequent transcriptomic studies. Methods: Semi-adherent rat alveolar macrophages NR8383 were grown at the ALI and coated with lung surfactant through nebulization using the VITROCELL® Cloud 6 System before being exposed to TiO2 NM105 NPs. After NP exposures, RNA was extracted and its quantity and quality were measured. Results: The VITROCELL® Cloud system allowed for uniform and ultrathin coating of cells with aerosolized surfactant mimicking physiological conditions in the lung. While nebulization of 57 μL of 30 mg/mL TiO2 and 114 μL of 15 mg/mL TiO2 nanoparticles yielded identical cell delivered dose, the reproducibility of dose as well as the quality of RNA extracted were better for 114 μL.

The prediction of diseases associated with nanomaterials is currently hampered by an incomplete understanding of the underlying mechanisms. Newly discovered nanomaterial quarantining and counteracting nanomaterial cycling fill that gap allowing Tilen Koklič, Tobias Stoeger, Janez Štrancar, and co-workers to incorporate these main modes of cellular response into a mechanistic model and predict in vivo inflammation solely on animal-free in vitro tests, as described in article number 2003913.

Cellulose nanocrystal and gold nanoparticles are assembled, in a unique way, to yield a novel modular glyconanomaterial whose surface is then easily engineered with one or two different headgroups, by...