Zebrafish is an aquatic organism that can be used for high content safety screening of engineered nanomaterials (ENMs). We demonstrate, for the first time, the use of high content bright-field and fluorescence-based imaging to compare the toxicological effect of transition metal oxide (CuO, ZnO, NiO and Co3O4) nanoparticles in zebrafish embryos and larvae. High content bright-field imaging demonstrated potent and dose-dependant hatching interference in the embryos, with the exception of Co3O4 which was relatively inert. We propose that the hatching interference was due to the shedding of Cu and Ni ions, compromising the activity of the hatching enzyme, ZHE1, similar to what we previously proposed for Zn2+. This hypothesis is based on the presence of metal–sensitive histidines in the catalytic center of this enzyme. Co-introduction of a metal ion chelator, diethylene triamine pentaacetic acid (DTPA), reversed the hatching interference of Cu, Zn and Ni. While neither the embryos nor larvae demonstrated morphological abnormalities, high content fluorescence-based imaging demonstrated that CuO, ZnO and NiO could induce increased expression of the heat shock protein 70:enhanced green fluorescence protein (hsp70:eGFP) in transgenic zebrafish larvae. Induction of this response by CuO required a higher nanoparticle dose than the amount leading to hatching interference. This response was also DTPA sensitive. In conclusion, we demonstrate that high content imaging of embryo development, morphological abnormalities and HSP70 expression can be used for hazard ranking and determining the dose-response relationships leading to ENM effects on the development of the zebrafish embryo.

The kidney is a major target for drug-induced toxicity. Drug-induced nephrotoxicity remains a major problem in the clinical setting, where the use of nephrotoxic drugs is often unavoidable. This leads frequently to acute kidney injury, and current problems are discussed. One strategy to avoid such problems would be the development of drugs with decreased nephrotoxic potential. However, the prediction of nephrotoxicity during preclinical drug development is difficult and nephrotoxicity is typically detected only late. Also, the nephrotoxic potential of newly approved drugs is often underestimated. Regulatory approved or validated in vitro models for the prediction of nephrotoxicity are currently not available. Here, we will review current approaches on the development of such models. This includes a discussion of three-dimensional and microfluidic models and recently developed stem cell based approaches. Most in vitro models have been tested with a limited number of compounds and are of unclear predictivity. However, some studies have tested larger numbers of compounds and the predictivity of the respective in vitro model had been determined. The results showed that high predictivity can be obtained by using primary or stem cell derived human renal cells in combination with appropriate end points.

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Zinc oxide (ZnO) nanoparticles have wide-ranging applications in a diverse array of industrial and consumer products, from ceramic manufacture and paint formulation to sunscreens and haircare products. Hence, it is imperative to rigorously characterize the health and safety aspects of human exposure to ZnO nanoparticles. This study therefore evaluated the cellular association, cytotoxic and inflammatory potential of spherical and sheet-shaped ZnO nanoparticles (of approximately the same specific surface area ≈30 cm²/g) on mouse and human cell lines (RAW-264.7 and BEAS-2B respectively), as well as with primary cultures of mouse bone marrow-derived dendritic cells (DC). The WST-8 assay demonstrated dose-dependent effects on the cytotoxicity of spherical and sheet-shaped ZnO nanoparticles on both RAW-264.7 and BEAS-2B cells, even though there was no significant effect of shape on the cytotoxicity of ZnO nanoparticles. There was however higher cellular association of spherical versus sheet-shaped ZnO nanoparticles. Measurement of reactive oxygen species (ROS) with the 2',7'-dichlorfluorescein-diacetate (DCFH-DA) assay indicated up to 4-folds increase in ROS level upon exposure to ZnO nanoparticles, but there was again no significant difference between both ZnO nanoparticle shapes. Exposure of primary dendritic cells to ZnO nanoparticles upregulated expression of CD80 and CD86 (well-known markers of DC activation and maturation) and stimulated release of pro-inflammatory cytokines--IL-6 and TNF-α, thus pointing to the potential of ZnO nanoparticles in inducing inflammation. Hence, our study indicated that ZnO nanoparticles can have potential detrimental effects on cells even at dosages where there are little or no observable cytotoxic effects.

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