Suitability of human and mammalian cells of different origin for the assessment of genotoxicity of metal and polymeric engineered nanoparticles

Abstract

Nanogenotoxicity is a crucial endpoint in safety testing of nanomaterials as it addresses potential mutagenicity, which has implications for risks of both genetic disease and carcinogenesis. Within the NanoTEST project, we investigated the genotoxic potential of well-characterised nanoparticles (NPs): titanium dioxide (TiO₂) NPs of nominal size 20 nm, iron oxide (8 nm) both uncoated (U-Fe₃O₄) and oleic acid coated (OC-Fe₃O₄), rhodamine-labelled amorphous silica 25 (Fl-25 SiO₂) and 50 nm (Fl-50 SiO) and polylactic glycolic acid polyethylene oxide polymeric NPs – as well as Endorem® as a negative control for detection of strand breaks and oxidised DNA lesions with the alkaline comet assay. Using primary cells and cell lines derived from blood (human lymphocytes and lymphoblastoid TK6 cells), vascular/central nervous system (human endothelial human cerebral endothelial cells), liver (rat hepatocytes and Kupffer cells), kidney (monkey Cos-1 and human HEK293 cells), lung (human bronchial 16HBE14o cells) and placenta (human BeWo b30), we were interested in which in vitro cell model is sufficient to detect positive (genotoxic) and negative (non-genotoxic) responses. All in vitro studies were harmonized, i.e. NPs from the same batch, and identical dispersion protocols (for TiO₂ NPs, two dispersions were used), exposure time, concentration range, culture conditions and time-courses were used. The results from the statistical evaluation show that OC-Fe₃O₄ and TiO₂ NPs are genotoxic in the experimental conditions used. When all NPs were included in the analysis, no differences were seen among cell lines – demonstrating the usefulness of the assay in all cells to identify genotoxic and non-genotoxic NPs. The TK6 cells, human lymphocytes, BeWo b30 and kidney cells seem to be the most reliable for detecting a dose-response.

• Cell models
• comet assay
• genotoxicity
• nanoparticles
• statistical analysis

Acknowledgements

We wish to acknowledge the additional technical support from Norma Houssein to generate the TiO₂ NP comet assay data.

Declaration of interest

The authors declare that there is no conflict of interest.

The work was supported by EC FP7 NanoTEST [Health-2007-1.3-4], contract no: 201335, EC FP7 QualityNano [INFRA-2010-1.131], contract no: 214547-2, EC FP7 NANoREG, [NMP.2012.1.3-3], contract no: 310584, EC FP7 NanoTOES [PITN-GA-2010-264506], EC FP7-PEOPLE-IEF Marie Curie grant [PIEF-GA-252858] and by NILU internal projects 106179 and 106170. The work by UH Bristol was carried out with the support of the Bristol Centre for Nanoscience and Quantum Information, University of Bristol.