An in vitro testing strategy towards mimicking the inhalation of high aspect ratio nanoparticles

Background: the challenge remains to reliably mimic human exposure to high aspect ratio nanoparticles (harn) via inhalation. sophisticated,multi-cellular in vitro models are a particular advantageous solution to this issue,especially when considering the need to provide realistic and efficient alternatives to invasive animal experimentation for harn hazard assessment. by incorporating a systematic test-bed of material characterisation techniques,a specific air-liquid cell exposure system with real-time monitoring of the cell-delivered harn dose in addition to key biochemical endpoints,here we demonstrate a successful approach towards investigation of the hazard of harn aerosols in vitro. methods: cellulose nanocrystals (cncs) derived from cotton and tunicates,with differing aspect ratios (~9 and ~80),were employed as model harn samples. specifically,well-dispersed and characterised cnc suspensions were aerosolised using an air liquid interface cell exposure system (alice) at realistic,cell-delivered concentrations ranging from 0.14 to 1.57 μg/cm2. the biological impact (cytotoxicity,oxidative stress levels and pro-inflammatory effects) of each harn sample was then assessed using a 3d multi-cellular in vitro model of the human epithelial airway barrier at the air liquid interface (ali) 24 hours post-exposure. additionally,the testing strategy was validated using both crystalline quartz (dq12) as a positive particulate control in the alice system and long fibre amosite asbestos (lfa) to confirm the susceptibility of the in vitro model to a fibrous insult. results: a rapid (≤4 min),controlled nebulisation of cnc suspensions enabled a dose-controlled and spatially homogeneous cnc deposition onto cells cultured under ali conditions. real-time monitoring of the cell-delivered cnc dose with a quartz crystal microbalance was accomplished. independent of cnc aspect ratio,no significant cytotoxicity (p > 0.05),induction of oxidative stress,or (pro)-inflammatory responses were observed up to the highest concentration of 1.57 μg/cm2. both dq12 and lfa elicited a significant (p < 0.05) pro-inflammatory response at sub-lethal concentrations in vitro.conclusion: in summary,whilst the present study highlights the benign nature of cncs,it is the advanced technological and mechanistic approach presented that allows for a state of the art testing strategy to realistically and efficiently determine the in vitro hazard concerning inhalation exposure of harn. © 2014 endes et al.; licensee biomed central ltd.