94 Metalsafety – In Vitro, ex Vivo and in Vivo Investigations on Particulate and Nanofibrous Metal Compounds

Metals and metal compounds are essential in daily life. Besides particulate materials nanofibrous material (nanowires) gain importance in innovative processes like optoelectronics. Toxicological data to assess the hazard is often available only for granular metals while data on nanowires is sparse. The project MetalSafety funded by the German BMBF aims at the development of an in vitro model to allow the grouping of different metal compounds with different bioavailability according to their toxicological hazard. Ex vivo and in vivo investigations are used to analyse the predictivity of the in vitro results and the underlying mode-of-action and dose-response relationship. Within this contribution the study concept is introduced. Silver and copper, both in particulate and nanofibrous form, are used across all examinations in vitro, ex vivo and in vivo. To allow an interspecies comparison cell lines derived from human and rat lung are used. Exposure to the materials can be investigated either submerse or with air-liquid-interface (ALI) conditions. The correlation between both species can also be examined ex vivo using precision-cut lung slices (PCLS) derived from human and rat lung tissue. Application in vivo by intratracheal instillation in rats is conducted to enable a validation of the in vitro and ex vivo screening models in a best case scenario under physiological conditions. Comparable endpoints in vitro, ex vivo as well as in vivo are measured during the study. This includes cytotoxicity endpoints and cytokine measurements as well as gene expression analyses. The lung tissue is also subjected to a histopathological examination.