title: Overestimation of nanoparticles-induced DNA damage determined by the comet assay.
abstract: The increasing use of engineered nanoparticles (NPs) in a wide range of commercial products raises concern about the possible risks that NPs pose to human health. Many aspects of the interaction between living cells and NPs are still unclear, and a reliable assessment of NP genotoxicity would be important. One of the most common tests used for genotoxicity is the comet assay, a sensitive method measuring DNA damage in individual cells. The assay was originally developed for soluble molecules, but it is also used in the assessment of genotoxicity of NPs. However, concerns have been raised recently about the reliability of this test in the case of NPs, but no conclusive results have been presented. Using nuclei isolated from human epithelial cells incubated with NPs, we obtained clear evidence of overestimation of NP genotoxicity by the comet assay in the case of CeO2, TiO2, SiO2, and polystyrene NPs. Removal of the NPs in the cytoplasm was effective in eliminating this genotoxicity overestimation (ex post damage) and determining the actual damage produced by the NPs during incubation with the cells (ex ante damage). This method could improve significantly the determination of NP genotoxicity in eukaryotic cells.
authors.affiliation: a Department of Molecular Medicine , Human Physiology Unit, University of Pavia , Pavia , Italy and.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ferraro
authors.affiliation: b Department of Chemistry , University of Pavia , Pavia , Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Anselmi-Tamburini
authors.affiliation: b Department of Chemistry , University of Pavia , Pavia , Italy.
authors.forename: Ilenia Giuseppina
authors.initials: IG
authors.lastname: Tredici
authors.affiliation: a Department of Molecular Medicine , Human Physiology Unit, University of Pavia , Pavia , Italy and.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Ricci
authors.affiliation: a Department of Molecular Medicine , Human Physiology Unit, University of Pavia , Pavia , Italy and.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Sommi
mesh_terms: D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D002470:Cell Survival; D002563:Cerium / Q000737:chemistry / Q000633:toxicity*; D020552:Comet Assay / Q000379:methods; D003593:Cytoplasm / Q000187:drug effects / Q000473:pathology; D004249:DNA Damage; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology; D006367:HeLa Cells; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D015203:Reproducibility of Results; D012822:Silicon Dioxide / Q000737:chemistry / Q000633:toxicity*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*
chemical_list: C009495:titanium dioxide; D002563:Cerium; C030583:ceric oxide; D012822:Silicon Dioxide; D014025:Titanium
keywords: Genotoxicity; nanotoxicology; nuclei isolation; single-nucleus gel electrophoresis assay