Metabolomics-on-a-chip approach to study hepatotoxicity of DDT, permethrin and their mixtures.

Despite the diversity of studies on pesticide toxicities, there is a serious lack of information concerning the toxic effect of pesticides mixtures. Dichlorodiphenyl-trichloroethane (DDT) and permethrin (PMT) are among the most prevalent pesticides in the environment and have been the subject of several toxicological studies. However, there are no data on the toxicity of their mixtures. In this study, we used an approach combining cell culture in microfluidic biochips with gas chromatography-mass spectrometry metabolomics profiling to investigate the biomarkers of toxicity of DDT, PMT and their mixtures. All parameters observed indicated that no significant effect was observed in hepatocytes cultures exposed to low doses (15 µm) of DDT and PMT. Conversely, combined low doses induce moderate oxidative stress and cell death. The toxic signature of high doses of pesticides (150 µm) was illustrated by severe oxidative stress and cell mortality. Metabolomics profiling revealed that hepatocytes exposure to DDT150, PMT150 and DDT150 and PMT150 cause important modulation in intermediates of glutathione pathway and tricarboxylic acid cycle, amino acids and metabolites associated to hepatic necrosis and inflammation (α-ketoglutarate, arginine and 2-hydroxybutyrate). These changes were more striking in the combined group. Finally, DDT150 led to a significant increase of benzoate, decanoate, octanoate, palmitate, stearate and tetradecanoate, which illustrates the estrogen modulation. This study demonstrates the potential of metabolomics-on-a-chip approach to improve knowledge on the mode of action of pesticides.

Long-term human primary hepatocyte cultures in a microfluidic liver biochip show maintenance of mRNA levels and higher drug metabolism compared with Petri cultures.

Human primary hepatocytes were cultivated in a microfluidic bioreactor and in Petri dishes for 13 days. mRNA kinetics in biochips showed an increase in the levels of CYP2B6, CYP2C19, CYP2C8, CYP3A4, CYP1A2, CYP2D6, HNF4a, SULT1A1, UGT1A1 mRNA related genes when compared with post extraction levels. In addition, comparison with Petri dishes showed higher levels of CYP2B6, CYP2C19, CYP2C8, CYP3A4, CYP1A2, CYP2D6 related genes at the end of culture. Functional assays illustrated a higher urea and albumin production over the period of culture in biochips. Bioreactor drug metabolism (midazolam and phenacetin) was not superior to the Petri dish after 2 days of culture. The CYP3A4 midazolam metabolism was maintained in biochips after 13 days of culture, whereas it was almost undetectable in Petri dishes. This led to a 5000-fold higher value of the metabolic ratio in the biochips. CYP1A2 phenacetin metabolism was found to be higher in biochips after 5, 9 and 13 days of culture. Thus, a 100-fold higher metabolic ratio of APAP in biochips was measured after 13 days of perfusion. These results demonstrated functional primary human hepatocyte culture in the bioreactor in a long-term culture. Copyright © 2016 John Wiley & Sons, Ltd.

Investigation of omeprazole and phenacetin first-pass metabolism in humans using a microscale bioreactor and pharmacokinetic models.

A new in vitro microfluidic platform (integrated insert dynamic microfluidic platform, IIDMP) allowing the co-culture of intestinal Caco-2 TC7 cells and of human primary hepatocytes was used to test the absorption and first-pass metabolism of two drugs: phenacetin and omeprazole. The metabolism of these drugs by CYP1A2, CYP2C19 and CYP3A4 was evaluated by the calculation of bioavailabilities and of intrinsic clearances using a pharmacokinetic (PK) model. To demonstrate the usefulness of the device and of the PK model, predictions were compared with in vitro and in vivo results from the literature. Based on the IIDMP experiments, hepatic in vivo clearances of phenacetin and omeprazole in the IIDMP were predicted to be 3.10 ± 0.36 and 1.46 ± 0.25 ml/min/kg body weight, respectively. This appeared lower than the in vivo observed data with values ranging between 11.9-19.6 and 5.8-7.5 ml/min/kg body weight, respectively. Then the calculated hepatic and intestinal clearances led to predicting an oral bioavailability of 0.85 and 0.77 for phenacetin and omeprazole versus 0.92 and 0.78 using separate data from the simple monoculture of Caco-2 TC7 cells and hepatocytes in Petri dishes. When compared with the in vivo data, the results of oral bioavailability were overestimated (0.37 and 0.71, respectively). The feasibility of co-culture in a device allowing the integration of intestinal absorption, intestinal metabolism and hepatic metabolism in a single model was demonstrated. Nevertheless, further experiments with other drugs are needed to extend knowledge of the device to predict oral bioavailability and intestinal first-pass metabolism.

Effects of DDT and permethrin on rat hepatocytes cultivated in microfluidic biochips: Metabolomics and gene expression study.

Dichlorodiphenyl-trichloroethane (DDT) and permethrin (PMT) are amongst most prevalent pesticides in the environment. Although their toxicity has been extensively studied, molecular mechanisms and metabolic effects remain unclear, including in liver where their detoxification occurs. Here, we used metabolomics, coupled to RT-qPCR analysis, to examine effects of DDT and PMT on hepatocytes cultivated in biochips. At 150 µM, DDT caused cell death, cytochrome P450 induction and modulation of estrogen metabolism. Metabolomics analysis showed an increase in some lipids and sugars after 6 h, and a decrease in fatty acids (tetradecanoate, octanoate and linoleate) after 24 h exposure. We also found a change in expression associated with genes involved in hepatic estrogen, lipid, and sugar metabolism. PMT at 150 µM perturbed lipid/sugar homeostasis and estrogen signaling pathway, between 2 and 6 h. After 24 h, lipids and sugars were found to decrease, suggesting continuous energy demand to detoxify PMT. Finally, at 15 µM, DDT and PMT appeared to have a small effect on metabolism and were detoxified after 24 h. Our results show a time-dependent perturbation of sugar/lipid homeostasis by DDT and PMT at 150 µM. Furthermore, DDT at high dose led to cell death, inflammatory response and oxidative stress.

Investigation of the hepatotoxicity of flutamide: pro-survival/apoptotic and necrotic switch in primary rat hepatocytes characterized by metabolic and transcriptomic profiles in microfluidic liver biochips.

We investigated the effects of the liver damage induced by flutamide in primary rat hepatocytes using liver microfluidic biochips. Flutamide is a non-steroidal anti-androgenic drug. Two flutamide concentrations, 10 µM and 100 µM, were used to expose the hepatocytes for 24h under perfusion. Thanks to the maintenance of hepatocyte differentiation phenotype and to the biotransformation performance in the microfluidic cultures, the metabolic ratio analysis of hydroxyflutamide, flutamide-gluthatione and hydroxyflutamide-gluthatione productions demonstrated saturation of the drug's biotransformation process and the maintenance of a high level of flutamide at 100 µM when compared to 10 µM. A microarray analysis comparing flutamide (10 or 100 µM) with controls revealed a common response for both concentrations illustrated by modulating the expression of the mRNA of genes associated with mitochondrial perturbation, of the proliferator-activated receptors (Ppar) signaling, lipid and fatty acid metabolism, antioxidant defense, and cell death pathways, consistently with in vitro and in vivo reports. Additionally to literature reports, our integration of the transcriptomic profiles demonstrated a specific dose dependent response. We found at 10 µM a typical pro-survival/apoptosis network activation (through IGF/PDGFD upstream route and via a downstream up regulation in CREB5, BCL2, IKBKG routes in the PI3K/signaling). We also found a down regulation of mRNA levels in sugar and amino acid metabolism pathways. At 100 µM a typical necrosis switch was observed associated with a down regulation of the tight junctions' pathway, a cellular aggregation and a reduction of the cell viability. Altogether our data demonstrated the potential and the sensitivity of our liver microfluidic cultures to evaluate xenobiotic toxicity by improving in vitro analysis and reproducing both in vitro and in vivo results. Finally, we proposed two integrated synthetic networks to describe the response of rat hepatocytes to both exposure concentrations of flutamide.

Development of a new microfluidic platform integrating co-cultures of intestinal and liver cell lines.

We developed a new biological model to mimic the organ-organ interactions between the intestine and the liver. We coupled polycarbonate cell culture inserts and microfluidic biochips in an integrated fluidic platform allowing dynamic co-cultures (called IIDMP for Integrated Insert in a Dynamic Microfluidic Platform). The intestinal compartment was simulated using Caco-2 TC7 cells and the liver one by HepG2 C3A. We showed that Caco-2 TC7 viability, barrier integrity and functionality (assessed by paracellular and active transport), were not altered during co-cultures in the bioreactor in comparison with the conventional insert Petri cultures. In parallel, the viability and metabolism of the HepG2 C3A cells were maintained in the microfluidic biochips. Then, as proof of concept, we used the bioreactor to follow the transport of phenacetin through the intestinal barrier and its metabolism into paracetamol by the CYP1A of the HepG2 C3A cells. Our results demonstrated the performance of this bioreactor with cell co-cultures compared to static co-culture controls in which weak biotransformation into paracetamol was detected. Our study illustrated the interest of such a bioreactor combining the advantages of a cell culture barrier and of liver microfluidic cultures in a common framework for in vitro studies.

Investigation of expression and activity levels of primary rat hepatocyte detoxication genes under various flow rates and cell densities in microfluidic biochips.

We investigated the behavior of primary rat hepatocytes in biochips using a microfluidic platform (the integrated dynamic cell culture microchip). We studied the effects of cell inoculation densities (0.2-0.5 × 10(6) cells/biochip) and perfusion flow rates (10, 25, and 40 µL/min) during 72 h of perfusion. No effects were observed on hepatocyte morphology, but the levels of mRNA and CYP1A2 activity were found to be dependent on the initial cell densities and flow rates. The dataset made it possible to extract a best estimated range of parameters in which the rat hepatocytes appeared the most functional in the biochips. Namely, at 0.25 × 10(6) inoculated cells cultivated at 25 µL/min for 72 h, we demonstrated better induction of the expression of all the genes analyzed in comparison with other cell densities and flow rates. More precisely, when primary rat hepatocytes were cultivated at these conditions, the time-lapse analysis demonstrated an over expression of CYP3A1, CYP2B1, ABCC1b and ABCC2 in the biochips when compared to the postextraction levels. Furthermore, the AHR, CYP1A2, GSTA2, SULT1A1, and UGT1A6 levels remained higher than 50% of the postextraction values whereas values of HNF4α, CEBP, and PXR remained higher than 20% during the duration of the culture process. Nevertheless, an important reduction in mRNA levels was found for the xenosensors CAR and FXR, and the related CYP (CYP2E1, CYP7A1, CYP3A2, and CYP2D2). CYP1A2 functionality was illustrated by 700 ± 100 pmol/h/10(6) cells resorufin production. This study highlighted the functionality in optimized conditions of primary rat hepatocytes in parallelized microfluidic cultures and their potential for drug screening applications.

Impact of alginate composition: from bead mechanical properties to encapsulated HepG2/C3A cell activities for in vivo implantation.

Recently, interest has focused on hepatocytes' implantation to provide end stage liver failure patients with a temporary support until spontaneous recovery or a suitable donor becomes available. To avoid cell damage and use of an immunosuppressive treatment, hepatic cells could be implanted after encapsulation in a porous biomaterial of bead or capsule shape. The aim of this study was to compare the production and the physical properties of the beads, together with some hepatic cell functions, resulting from the use of different material combinations for cell microencapsulation: alginate alone or combined with type I collagen with or without poly-L-lysine and alginate coatings. Collagen and poly-L-lysine increased the bead mechanical resistance but lowered the mass transfer kinetics of vitamin B12. Proliferation of encapsulated HepG2/C3A cells was shown to be improved in alginate-collagen beads. Finally, when the beads were subcutaneously implanted in mice, the inflammatory response was reduced in the case of alginate mixed with collagen. This in vitro and in vivo study clearly outlines, based on a systematic comparison, the necessity of compromising between material physical properties (mechanical stability and porosity) and cell behavior (viability, proliferation, functionalities) to define optima hepatic cell microencapsulation conditions before implantation.