Cellular Interactions and Biological Responses to Titanium Dioxide Nanoparticles in HepG2 and BEAS-2B Cells: Role of Cell Culture Media

We showed previously that exposure of human lung cells (BEAS-2B) to TiO2 nanoparticles (nano-TiO2) produced micronuclei (MN) only when the final concentration of protein in the cell-culture medium was at least 1%. Nanoparticles localize in the liver; thus, we exposed human liver cells (HepG2) to nano-TiO2 and found the same requirement for MN induction. Nano-TiO2 also formed small agglomerates in medium containing as little as 1% protein and caused cellular interaction as measured by side scatter by flow cytometry and DNA damage (comet assay) in HepG2 cells. Nano-TiO2 also increased the activity of the inflammatory factor NFkB but not of AP1 in a reporter-gene HepG2 cell line. Suspension of nano-TiO2 in medium containing 0.1% protein was sufficient for induction of MN by the nanoparticles in either BEAS-2B or HepG2 cells as long the final concentration of protein in the cell-culture medium was at least 1%. Environ. Mol. Mutagen. 55:336-342, 2014. (c) 2014 Wiley Periodicals, Inc.