Applied In Vitro ToxicologyVol. 8, No. 2 Original ArticlesFree Access Abstract Introduction: Coculture models have been extensively used for assessing the toxicity of fibers and particles. However, once cell lines are mixed in the same tissue culture well, it is difficult to evaluate differential cell toxicity without using specific cell markers, which might not be compatible with assays requiring living cells such as a particle-induced oxidative stress assay by flow cytometry.