Publications by authors named "L Tolosa"

108 Publications

The in vitro assessment of the toxicity of volatile, oxidisable, redox-cycling compounds: phenols as an example.

Arch Toxicol 2021 Jun 25;95(6):2109-2121. Epub 2021 May 25.

Unidad Mixta de Hepatología Experimental, Instituto de Investigación Sanitaria, Hospital La Fe, Valencia, Spain.

Phenols are regarded as highly toxic chemicals. Their effects are difficult to study in in vitro systems because of their ambiguous fate (degradation, auto-oxidation and volatility). In the course of in vitro studies of a series of redox-cycling phenols, we found evidences of cross-contamination in several in vitro high-throughput test systems, in particular by trimethylbenzene-1, 4-diol/trimethylhydroquinone (TMHQ) and 2,6-di-tertbutyl-4-ethylphenol (DTBEP), and investigated in detail the physicochemical basis for such phenomenon and how to prevent it. TMHQ has fast degradation kinetics followed by significant diffusion rates of the resulting quinone to adjacent wells, other degradation products being able to air-diffuse as well. DTBEP showed lower degradation kinetics, but a higher diffusion rate. In both cases the in vitro toxicity was underestimated because of a decrease in concentration, in addition to cross-contamination to neighbouring wells. We identified four degradation products for TMHQ and five for DTBEP indicating that the current effects measured on cells are not only attributable to the parent phenolic compound. To overcome these drawbacks, we investigated in detail the physicochemical changes occurring in the course of the incubation and made use of gas-permeable and non-permeable plastic seals to prevent it. Diffusion was greatly prevented by the use of both plastic seals, as revealed by GC-MS analysis. Gas non-permeable plastic seals, reduced to a minimum compounds diffusion as well oxidation and did not affect the biological performance of cultured cells. Hence, no toxicological cross-contamination was observed in neighbouring wells, thus allowing a more reliable in vitro assessment of phenol-induced toxicity.
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http://dx.doi.org/10.1007/s00204-021-03036-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8166692PMC
June 2021

High-Content Screening for the Detection of Drug-Induced Oxidative Stress in Liver Cells.

Antioxidants (Basel) 2021 Jan 13;10(1). Epub 2021 Jan 13.

Unidad de Hepatología Experimental, Instituto de Investigación Sanitaria La Fe, 46026 Valencia, Spain.

Drug-induced liver injury (DILI) remains a major cause of drug development failure, post-marketing warnings and restriction of use. An improved understanding of the mechanisms underlying DILI is required for better drug design and development. Enhanced reactive oxygen species (ROS) levels may cause a wide spectrum of oxidative damage, which has been described as a major mechanism implicated in DILI. Several cell-based assays have been developed as in vitro tools for early safety risk assessments. Among them, high-content screening technology has been used for the identification of modes of action, the determination of the level of injury and the discovery of predictive biomarkers for the safety assessment of compounds. In this paper, we review the value of in vitro high-content screening studies and evaluate how to assess oxidative stress induced by drugs in hepatic cells, demonstrating the detection of pre-lethal mechanisms of DILI as a powerful tool in human toxicology.
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http://dx.doi.org/10.3390/antiox10010106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7828515PMC
January 2021

Application of high-content screening for the study of hepatotoxicity: Focus on food toxicology.

Food Chem Toxicol 2021 Jan 19;147:111872. Epub 2020 Nov 19.

Unidad de Hepatología Experimental, Instituto de Investigación Sanitaria La Fe, Valencia, 46026, Spain. Electronic address:

Safety evaluation of thousands of chemicals that are directly added to or come in contact with food is needed. Due to the central role of the liver in intermediary and energy metabolism and in the biotransformation of foreign compounds, the hepatotoxicity assessment is essential. New approach methodologies have been proposed for the safety evaluation of compounds with the idea of rapidly gaining insight into effects on biochemical mechanisms and cellular processes and screening large number of compounds. In this sense, high-content screening (HCS) is the application of automated microscopy and image analysis for better understanding of complex biological functions and mechanisms of toxicity. HCS multiparametric measurements have been shown to be a useful tool in early toxicity testing during drug development, but also in assessing the impact from food chemicals and environmental toxicants. Reviewing the use of cellular imaging technology in the safety evaluation of food-relevant chemicals offers evidence about the impact of this technology in safety assessment.
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http://dx.doi.org/10.1016/j.fct.2020.111872DOI Listing
January 2021

Comparing in vitro human liver models to in vivo human liver using RNA-Seq.

Arch Toxicol 2021 02 27;95(2):573-589. Epub 2020 Oct 27.

Department of Toxicogenomics, School of Oncology and Developmental Biology (GROW), Maastricht University, Maastricht, The Netherlands.

The liver plays an important role in xenobiotic metabolism and represents a primary target for toxic substances. Many different in vitro cell models have been developed in the past decades. In this study, we used RNA-sequencing (RNA-Seq) to analyze the following human in vitro liver cell models in comparison to human liver tissue: cancer-derived cell lines (HepG2, HepaRG 3D), induced pluripotent stem cell-derived hepatocyte-like cells (iPSC-HLCs), cancerous human liver-derived assays (hPCLiS, human precision cut liver slices), non-cancerous human liver-derived assays (PHH, primary human hepatocytes) and 3D liver microtissues. First, using CellNet, we analyzed whether these liver in vitro cell models were indeed classified as liver, based on their baseline expression profile and gene regulatory networks (GRN). More comprehensive analyses using non-differentially expressed genes (non-DEGs) and differential transcript usage (DTU) were applied to assess the coverage for important liver pathways. Through different analyses, we noticed that 3D liver microtissues exhibited a high similarity with in vivo liver, in terms of CellNet (C/T score: 0.98), non-DEGs (10,363) and pathway coverage (highest for 19 out of 20 liver specific pathways shown) at the beginning of the incubation period (0 h) followed by a decrease during long-term incubation for 168 and 336 h. PHH also showed a high degree of similarity with human liver tissue and allowed stable conditions for a short-term cultivation period of 24 h. Using the same metrics, HepG2 cells illustrated the lowest similarity (C/T: 0.51, non-DEGs: 5623, and pathways coverage: least for 7 out of 20) with human liver tissue. The HepG2 are widely used in hepatotoxicity studies, however, due to their lower similarity, they should be used with caution. HepaRG models, iPSC-HLCs, and hPCLiS ranged clearly behind microtissues and PHH but showed higher similarity to human liver tissue than HepG2 cells. In conclusion, this study offers a resource of RNA-Seq data of several biological replicates of human liver cell models in vitro compared to human liver tissue.
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http://dx.doi.org/10.1007/s00204-020-02937-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7870774PMC
February 2021

Induced pluripotent stem cells for the treatment of liver diseases: challenges and perspectives from a clinical viewpoint.

Ann Transl Med 2020 Apr;8(8):566

Unidad de Hepatología Experimental, Instituto de Investigación Sanitaria La Fe, Valencia, Spain.

The only curative treatment for severe end-stage liver disease (ESLD) is liver transplantation (LT) but it is limited by the shortage of organ donors. The increase of the incidence of liver disease has led to develop new therapeutic approaches such as liver cell transplantation. Current challenges that limit a wider application of this therapy include a limited cell source and the poor engraftment in the host liver of cryopreserved hepatocytes after thawing. Induced pluripotent stem cells (iPSCs) that can be differentiated into hepatocyte-like cells (HLCs) are being widely explored as an alternative to human hepatocytes because of their unlimited proliferation capacity and their potential ability to avoid the immune system. Their large-scale production could provide a new tool to produce enough HLCs for treating patients with metabolic diseases, acute liver failure (ALF), those with ESLD or patients not considered for organ transplantation. In this review we discuss current challenges for generating differentiated cells compatible with human application as well as in-depth safety evaluation. This analysis highlights the uncertainties and deficiencies that should be addressed before their clinical use but also points out the potential benefits that will produce a great impact in the field of hepatology.
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http://dx.doi.org/10.21037/atm.2020.02.164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7347783PMC
April 2020