title: Comparative toxicity of 24 manufactured nanoparticles in human alveolar epithelial and macrophage cell lines.
abstract: BACKGROUND
  A critical issue with nanomaterials is the clear understanding of their potential toxicity. We evaluated the toxic effect of 24 nanoparticles of similar equivalent spherical diameter and various elemental compositions on 2 human pulmonary cell lines: A549 and THP-1. A secondary aim was to elaborate a generic experimental set-up that would allow the rapid screening of cytotoxic effect of nanoparticles. We therefore compared 2 cytotoxicity assays (MTT and Neutral Red) and analyzed 2 time points (3 and 24 hours) for each cell type and nanoparticle. When possible, TC50 (Toxic Concentration 50 i.e. nanoparticle concentration inducing 50% cell mortality) was calculated.
  
  
  RESULTS
  The use of MTT assay on THP-1 cells exposed for 24 hours appears to be the most sensitive experimental design to assess the cytotoxic effect of one nanoparticle. With this experimental set-up, Copper- and Zinc-based nanoparticles appear to be the most toxic. Titania, Alumina, Ceria and Zirconia-based nanoparticles show moderate toxicity, and no toxicity was observed for Tungsten Carbide. No correlation between cytotoxicity and equivalent spherical diameter or specific surface area was found.
  
  
  CONCLUSIONS
  Our study clearly highlights the difference of sensitivity between cell types and cytotoxicity assays that has to be carefully taken into account when assessing nanoparticles toxicity.
authors.affiliation: INSERM, Unité 700, Paris, France; Université Paris 7, Faculté de Médecine, site X, Bichat, Paris, France, and INSERM, Unité U955, Créteil, F-94010, France; Université Paris 12, Faculté de Médecine, Créteil, F-94010, France. sophie.lanone@inserm.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Lanone
authors.forename: Françoise
authors.initials: F
authors.lastname: Rogerieux
authors.forename: Jorina
authors.initials: J
authors.lastname: Geys
authors.forename: Aurélie
authors.initials: A
authors.lastname: Dupont
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Maillot-Marechal
authors.forename: Jorge
authors.initials: J
authors.lastname: Boczkowski
authors.forename: Ghislaine
authors.initials: G
authors.lastname: Lacroix
authors.forename: Peter
authors.initials: P
authors.lastname: Hoet