Comparative transcriptomes of Caco-2 cells cultured under dynamic and static conditions following exposure to titanium dioxide and zinc oxide nanomaterials. Comparative transcriptomes of Caco-2 cells cultured under dynamic and static conditions following exposure to titanium dioxide and zinc oxide nanomaterials

Due to the widespread application of food-relevant inorganic nanomaterials, the gastrointestinal tract is potentially exposed to these materials. Gut-on-chip in vitro model systems are proposed for the investigation of compound toxicity as they better recapitulate the in vivo human intestinal environment than static models, due to the added shear stresses associated with the flow of medium in line with what cells experience in vivo. We aimed to compare the cellular responses of intestinal epithelial Caco-2 cells at the gene expression level upon TiO2 (E171) and ZnO (NM110) nanomaterial exposure when cultured under dynamic and static conditions. For this, we applied whole genome transcriptome analyses. Differentially expressed genes and related biological processes revealed culture condition specific responses upon exposure to TiO2 and ZnO nanomaterials. The materials had more effects on cells cultured in the gut-on-chip when compared to the static model, indicating that shear stress might be a major factor in cell susceptibility. This is the first report on application of a gut-on-chip system to evaluate cellular responses upon TiO2 and ZnO nanomaterials compared to a static system and extends current knowledge on nanomaterial-cell interactions and toxicity assessment. Dynamically cultured cells appear to be more sensitive and the gut-on-chip might thus be an attractive model to be used more extensively in the toxicological hazard characterization. Overall design: Microarray analysis was performed on Caco-2 cells that were exposed to TiO2 or ZnO for 6hrs after being cultured statically or in a gut-on-chip device for 21 days.

鉴于与食品相关的无机纳米材料应用日益广泛，胃肠道存在接触此类材料的潜在风险。微流控肠道芯片（gut-on-chip）体外模型被提出用于化合物毒性研究，相较于静态培养模型，该模型能够更好地复现人体内的肠道生理环境——这是因为其引入了与体内细胞所受一致的、由培养基流动产生的剪切应力。
本研究旨在对比动态与静态培养条件下，肠道上皮Caco-2细胞暴露于二氧化钛（TiO₂，E171）与氧化锌（ZnO，NM110）纳米材料后，基因表达层面的细胞应答差异。为此，我们开展了全基因组转录组分析。差异表达基因及相关生物学过程表明，暴露于TiO₂与ZnO纳米材料后，细胞应答呈现培养条件特异性特征。与静态模型相比，肠道芯片培养的细胞受纳米材料的影响更为显著，提示剪切应力可能是影响细胞易感性的核心因素。
本研究首次报道了将肠道芯片系统与静态培养系统对比，用于评估TiO₂与ZnO纳米材料引发的细胞应答的应用，拓展了当前关于纳米材料-细胞相互作用及毒性评估的认知。动态培养的细胞表现出更高的敏感性，因此肠道芯片有望成为更广泛应用于毒理学危害表征的理想模型。
实验总体设计：将Caco-2细胞分别进行静态培养或在肠道芯片装置中培养21天后，暴露于TiO₂或ZnO纳米材料6小时，随后开展微阵列分析。