title: Comparative genotoxicity of nanosilver in human liver HepG2 and colon Caco2 cells evaluated by a flow cytometric in vitro micronucleus assay.
abstract: Two widely used in vitro cell culture models, human liver HepG2 cells and human colon Caco2 cells, and flow cytometry techniques were evaluated as tools for rapid screening of potential genotoxicity of food-related nanosilver. Comparative genotoxic potential of 20 nm silver was evaluated in HepG2 and Caco2 cell cultures by a flow cytometric-based in vitro micronucleus assay. The nanosilver, characterized by the dynamic light scattering, transmission electron microscopy and inductively coupled plasma-mass spectrometry analysis, showed no agglomeration of the silver nanoparticles. The inductively coupled plasma-mass spectrometry and transmission electron microscopy analysis demonstrated the uptake of 20 nm silver by both cell types. The 20 nm silver exposure of HepG2 cells increased the concentration-dependent micronucleus formation sevenfold at 10 µg ml(-1) concentration in attached cell conditions and 1.3-fold in cell suspension conditions compared to the vehicle controls. However, compared to the vehicle controls, the 20 nm silver exposure of Caco2 cells increased the micronucleus formation 1.2-fold at a concentration of 10 µg ml(-1) both in the attached cell conditions as well as in the cell suspension conditions. Our results of flow cytometric in vitro micronucleus assay appear to suggest that the HepG2 cells are more susceptible to the nanosilver-induced micronucleus formation than the Caco2 cells compared to the vehicle controls. However, our results also suggest that the widely used in vitro models, HepG2 and Caco2 cells and the flow cytometric in vitro micronucleus assay are valuable tools for the rapid screening of genotoxic potential of nanosilver and deserve more careful evaluation.
authors.affiliation: Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, Laurel, MD, 20708, USA.
authors.forename: Saura C
authors.initials: SC
authors.lastname: Sahu
authors.forename: Joyce
authors.initials: J
authors.lastname: Njoroge
authors.forename: Steven M
authors.initials: SM
authors.lastname: Bryce
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Yourick
authors.forename: Robert L
authors.initials: RL
authors.lastname: Sprando
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D018938:Caco-2 Cells; D003106:Colon / Q000166:cytology / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D005434:Flow Cytometry; D056945:Hep G2 Cells; D006801:Humans; D008099:Liver / Q000166:cytology / Q000187:drug effects; D015162:Micronucleus Tests; D053758:Nanoparticles / Q000633:toxicity*; D012834:Silver / Q000633:toxicity*; D018675:Toxicity Tests
chemical_list: D012834:Silver
keywords: Caco2 cells; HepG2 cells; Nanoparticles; flow cytometry; genotoxicity; micronucleus; nanosilver; silver nanoparticles