Ingestion of titanium dioxide (TiO2) nanoparticles from products such as agricultural chemicals, processed food, and nutritional supplements is nearly unavoidable. The gastrointestinal tract serves as a critical interface between the body and the external environment, and is the site of essential nutrient absorption. The goal of this study was to examine the effects of ingesting the 30 nm TiO2 nanoparticles with an in vitro cell culture model of the small intestinal epithelium, and to determine how acute or chronic exposure to nano-TiO2 influences intestinal barrier function, reactive oxygen species generation, proinflammatory signaling, nutrient absorption (iron, zinc, fatty acids), and brush border membrane enzyme function (intestinal alkaline phosphatase). A Caco-2/HT29-MTX cell culture model was exposed to physiologically relevant doses of TiO2 nanoparticles for acute (four hours) or chronic (five days) time periods. Exposure to TiO2 nanoparticles significantly decreased intestinal barrier function following chronic exposure. Reactive oxygen species (ROS) generation, proinflammatory signaling, and intestinal alkaline phosphatase activity all showed increases in response to nano-TiO2. Iron, zinc, and fatty acid transport were significantly decreased following exposure to TiO2 nanoparticles. This is because nanoparticle exposure induced a decrease in absorptive microvilli in the intestinal epithelial cells. Nutrient transporter protein gene expression was also altered, suggesting that cells are working to regulate the transport mechanisms disturbed by nanoparticle ingestion. Overall, these results show that intestinal epithelial cells are affected at a functional level by physiologically relevant exposure to nanoparticles commonly ingested from food.

The use of nanomaterials to enhance properties of food and improve delivery of orally administered drugs has become common, but the potential health effects of these ingested nanomaterials remain unknown. The goal of this study is to characterize the properties of silicon dioxide (SiO) nanoparticles (NP) that are commonly used in food and food packaging, and to investigate the effects of physiologically realistic doses of SiO NP on gastrointestinal (GI) health and function. In this work, an in vitro model composed of Caco-2 and HT29-MTX co-cultures, which represent absorptive and goblet cells, was used. The model was exposed to well-characterized SiO NP for acute (4 h) and chronic (5 d) time periods. SiO NP exposure significantly affected iron (Fe), zinc (Zn), glucose, and lipid nutrient absorption. Brush border membrane intestinal alkaline phosphatase (IAP) activity was increased in response to nano-SiO. The barrier function of the intestinal epithelium, as measured by transepithelial electrical resistance, was significantly decreased in response to chronic exposure. Gene expression and oxidative stress formation analysis showed NP altered the expression levels of nutrient transport proteins, generated reactive oxygen species, and initiated pro-inflammatory signaling. SiO NP exposure damaged the brush border membrane by decreasing the number of intestinal microvilli, which decreased the surface area available for nutrient absorption. SiO NP exposure at physiologically relevant doses ultimately caused adverse outcomes in an in vitro model.

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given the central role of the liver in drug metabolism and detoxification, strong incentives exist to create new physiologically relevant, human-based, in vitro liver models which would offer better prediction of drug-induced liver injury in humans. Human hepatic HepaRG cells offer a spontaneous coculture model of hepatocytes and cholangiocytes, and maintain in vivo liver-specific functions, including phase I-III metabolism in 2D and 3D culture. [1] HepaRG cells are considered a sustainable surrogate to primary human hepatocytes [1] and a good cell model for pharmaceutical purposes, and therefore were the chosen cell type for this study.Despite many advances being made in the studies of 3D cellular models, there is still an unmet need for nondestructive quantitative assays. Many of the assays currently on the market were designed for 2D or suspension models, not for 3D culture models. Often, it is unknown if the reagents used in the assays can penetrate to the center of the 3D model, and for lytic assays, if it is possible for the reagent to disrupt every cell in the model. Another major issue that has come up with using these assays for 3D models is the optimization needed for each specific 3D model and each specific assay, regarding concentration of reagents, incubation time, and optimal cell number.Given established endpoint toxicity assays are often incompatible with assessing 3D dense tissues without destruction of the sample, we investigated the use of optical coherence tomography (OCT) as a novel approach to assess cellular activity nondestructively, and quantitatively, in response to acetaminophen (APAP) hepatotoxicity.OCT is an optical imaging modality that achieves micrometer resolution at millimeter depth. [2,3] Its main application is in the field of ophthalmology. [4] OCT enables fast label-free imaging of highly scattering tissues both in vitro and in vivo. Hence, it found applications in the nondestructive time-lapse imaging of in vitro engineered tissues throughout tissue development. [5,6] In this study, we investigated whether OCT together with speckle-variance techniques can be used to go beyond detecting live cells against inanimate biomaterials and can assess noninvasively, and in a dose-dependent manner, reduction in cellular activity associated with drug toxicity in 3D liver spheroids after exposure to a prototypical hepatotoxin, acetaminophen. (DILI) is the leading cause of failure in preclinical drug development and withdrawals. Given the central role of the liver in drug metabolism and detoxification, strong incentives exist to create new physiologically relevant, human-based, 3D in vitro liver models which will offer better prediction of DILI. However, most cell metabolic assays are designed for 2D culture and are not always suitable to assess 3D cultures; in addition, there is an emerging need to develop novel nondestructive assays to assess cell activity in a time-lapse fashion. In this study, optical coherence tomography (OCT) is used to measure the viability on 3D liver spheroids af...

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