title: [Polyploidy induction by spherical size standard polystyrene particles in a Chinese hamster cell line CHL].
abstract: To investigate relationships between particle (as a model of aggregates) size in a nanomaterial test suspension and its cytotoxicity, a series of eleven sizes of polystyrene (PS) particles were tested in the cytotoxicity test and the chromosome aberration test by using a Chinese hamster cell line CHL. The PS particles were spheres with defined diameters ranging from 0.1 to 9.2 µm. A series of eight sizes of particles with diameters ranging from 0.92 to 4.45 µm showed stronger cytotoxicity than the others. There was a marked difference in cytotoxicity between the 4.45- and 5.26-µm particles. The 0.92- to 4.45-µm particles did not induce structural chromosome aberrations but induced a high frequency of polyploidy in the chromosome aberration test. The 5.26-µm particles showed very weak induction of polyploidy. The incorporation of the 4.45-µm particles into CHL cells was observed by scanning electron microscopy (SEM). Some cells incorporated more than 10 particles. The semi-quantitative measurement of incorporation of particles into cells was performed by flow cytometry with a parameter of side scattered light (SSC) intensity. It showed that CHL cells preferably incorporated the 4.45-µm particles to the 5.26-µm particles. These findings suggest that CHL cells may have a kind of size-recognition ability and incorporate a particular size of particles. The particles may prevent a normal cytokinesis resulting in polyploidy induction. Nanomaterials also may show size-dependent toxicity. Data on particle (or aggregate) size distribution in the test suspension should be provided to evaluate properly the results of toxicity tests of nanomaterials.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Matsuoka
authors.forename: Agneta
authors.initials: A
authors.lastname: Önfelt
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Kazuo
authors.initials: K
authors.lastname: Isama
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sakoda
authors.forename: Reiko
authors.initials: R
authors.lastname: Kato
authors.forename: Keiko
authors.initials: K
authors.lastname: Sakai
authors.forename: Shingo
authors.initials: S
authors.lastname: Niimi
mesh_terms: D024422:Aneugens / Q000378:metabolism / Q000633:toxicity*; D000818:Animals; D002460:Cell Line; D002869:Chromosome Aberrations / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009152:Mutagenicity Tests; D049329:Nanostructures; D010316:Particle Size; D011123:Polyploidy; D011137:Polystyrenes / Q000378:metabolism / Q000633:toxicity*
chemical_list: D024422:Aneugens; D011137:Polystyrenes