The rapid increase in production, use and release of engineered nanoparticles (ENPs)
demands a thorough investigation of their potential ecotoxicological effects. Focussed on the aquatic environment, cell lines from rainbow trout (Oncorhynchus mykiss) were used to study the effects of ENPs on fish. A novel two-compartment intestinal barrier model was developed by growing monolayers of the rainbow trout intestinal cell line (RTgutGC) on permeable membrane supports. Cells grow as polarized monolayers, express the tight junction protein ZO-1 and build up an epithelium with a transepithelial electrical resis- tance compared to the in vivo situation.
Fluorescent polystyrene nanoparticles (PS-NPs) were used to demonstrate the barrier function of the cells. RTgutGC cells take up large amounts of PS-NPs as shown by fluorescence measurement and microscopy, but almost completely prevent the translocation of PS-NPs through the epithelium. To study the effects of ENPs in more detail, different engineered metal and metal oxide nanoparticles (Ag, CuO, ZnO, TiO2) were applied to the cells and their toxicity as well as their translocation through the model epithelium explored. It could be shown that RTgutGC cells develop a much higher resistance against the toxicity of both Ag and CuO NPs when grown as polarized monolayer on permeable membranes compared to normal growth conditions on non-permeable culture support. Large amounts of translocated NPs or metal ions derived from the particles could be observed after incubation of the cells with CuO and ZnO NPs. In contrast, Ag NPs were only translocated to a very limited amount while TiO2 NPs were not translocated at all.
These data give new insights in the effects of ENPs on fish intestinal epithelial cells. The presented in vitro model has been shown to be a suitable tool to simultaneously assess ENP toxicity and translocation and will be a valuable system for future studies, e.g.
regarding the involved molecular and cellular mechanisms.