Abstracts / Toxicology Letters 238S (2015) S56–S383 S179 P07-019 Assessment of respiratory toxicity of ITER-like tungsten metal nanoparticles using an in vitro 3D human airway epithelium model I. George 1,* , A. Hagège 2 , N. Herlin 3 , D. Vrel 4 , J. Rose 5 , M. Sanles 5 , T. Orsière 6 , C. Uboldi 6 , C. Grisolia 7 , B. Rousseau 1 , V. Malard 8 1 CEA/Saclay, DSV-iBiTec-s-SCBM-LMT, Gif sur Yvette Cedex, France 2 Institute of Analytical Sciences (ISA), UMR 5280, 69100 Villeurbanne, France 3 CEA/Saclay, Iramis, 91191 Gif sur Yvette Cedex, France 4 Université Paris XIII, Laboratoire des Sciences des Procédés et des Matériaux, 93430 Villetaneuse, France 5 Aix-Marseille Université, CNRS, IRD, CEREGE UM34, 13545 Aix en Provence, France 6 Aix Marseille Université, UMR CNRS 7263 – IRD 237, 13385 Marseille cedex 05, France 7 CEA, IRFM, F-13108 Saint Paul lez Durance, France 8 CEA/Marcoule, DSV-iBEB-SBTN-LBSP, F-30207 Bagnols sur Cèze cedex, France During ITER operation, tritiated tungsten nanoparticles (W- NPs) will be generated. They could be possibly released in the tokamak vicinity during a “Loss of Vacuum Accident” (LOVA). Acci- dental inhalation of such radioactive NPs could be harmful for ITER workers. Given the deficit of knowledge concerning their potential radiotoxicity, we evaluated W-NP toxicity on an inno- vative 3D in vitro cell model of the human airway epithelium grown on air-liquid-interface, MucilAir ® . This model is character- ized by similar morphology and functions of the normal human airway epithelium and by mucus secretion and cilia beating. Epithe- lia were exposed to either W-NPs produced by planetary milling (50–100 nm), soluble tungsten (WO 4 ), or tungsten carbide cobalt alloy (WC-Co) positive control, for 24 h at 10; 20; 50 g/cm 2 . Due to the long shelf life of this model, NP cytotoxicity was stud- ied immediately after treatment and in a kinetic mode up to 1 month after cell exposure to assess the reversibility of toxic effects. Acute and long-term toxicities were monitored by several end- points: (1) epithelial tightness, (2) cellular metabolic activity, (3) pro-inflammatory response, (4) mucus secretion, and (5) morpho- logical modifications. Transmission Electronic Microscopy (TEM) observations and ICP-MS measurements were performed to deter- mine NP entry, behaviour and passage across the MucilAir ® model. After 24 h of W-treatment, TransEpithelial Electric Resistance and metabolic activity decreased and IL-8 apical secretion increased (coupled with mucus hyper-secretion). These results were more or less pronounced depending on the tungsten form. One week later, the effects were no longer observed for W-NP treatment but still observed for WO 4 and WC-Co. Different tungsten cellular distribu- tions were found in function of the restoration period and tungsten form. More than 90% of W0 4 cross the epithelial barrier in 24 h whereas W-NPs continue to cross 1 week after treatment. In con- clusion, our first results have shown that tungsten has limited and transient impacts on human pulmonary epithelium. The MucilAir ® model is a valuable tool for monitoring the W-translocation and the reversibility of its toxic effects. Tritiated W-NPs are currently being studied to evaluate the combined effects of chemical and radioactive stress. http://dx.doi.org/10.1016/j.toxlet.2015.08.519 P07-020 Pro-drug activation in dynamic microphysiological fluidic systems interconnecting liver and tumor microtissues J. Kim 1 , R. Marchan 2 , K. Boonen 3 , S. Hammad 2 , B. Landuyt 3 , J.G. Hengstler 2 , A. Hierlemann 1 , O. Frey 1 , J. Kelm 4,* 1 ETH, Department of Biosystems Science and Engineering, Zürich, Switzerland 2 IFADO, System Toxicology, Dortmund, Germany 3 KU Leuven, Research Group of Functional Genomics and Proteomics, Leuven, Belgium 4 InSphero AG, Schlieren, Switzerland Rational development of more physiologic in-vitro models includes the design of robust and flexible 3D-microtissue-based multi-tissue devices, which allow for tissue-tissue interactions. The newly developed microfluidic device consists of interconnected multiple micro-chambers, which are loaded with preformed spher- ical microtissues. Gravity-driven flow is generated from on-chip reservoirs through automated chip-tilting without any need for additional tubing and external pumps. This tilting concept allows for operating up to 48 devices in parallel to test various drug con- centrations with a sufficient number of replicates. Rat and human liver and colorectal tumor microtissues were interconnected on the chip and cultured over 8 days in the presence of the pro-drug cyclophosphamide. Cyclophosphamide has a significant impact on tumor growth but only after bio-activation by the liver. This effect was only observed in the perfused and interconnected co-cultures of the different microtissue types on-chip, whereas the discontin- uous transfer of supernatant via pipetting from liver microtissues that have been treated with cyclophosphamide in culture wells did not significantly affect tumor growth. The results indicate the utility and multi-tissue functionality of this platform as well as the impor- tance of continuous medium circulation to assess liver-mediated pro-drug activation. http://dx.doi.org/10.1016/j.toxlet.2015.08.520 P07-022 Evaluation of real time cell viability assays multiplexed with other methods T. Riss * , B. Hook, S. Duellman Promega Corporation, Madison, United States The development of novel assay technologies has made it pos- sible to measure the number of live or dead cells in culture in real time over a period of days using standard multi-well plate readers. An advantage of using non-toxic reagents is the viable population of cells remains in the sample wells following viabil- ity measurements. However, the chemical compatibility of these new assay reagents has not been thoroughly studied for all poten- tial assay combinations available for multiplexing. The purpose of this study was to determine if recently developed assay reagents to detect live and dead cells in real time would affect the health of cells in culture and/or the ability to multiplex with other assay chemistries. The methods used included exposing cells to the real time assay reagents for up to 3 days and confirming cell viability measurements using independent orthogonal methods (ATP assay and viable cell protease marker). In addition, other assay endpoints (firefly luciferase reporter, caspase-3/7 activity, RNA extraction) were measured from cells cultured in the presence or absence of