ABSTRACT: Evaluation of Human Embryonic Stem Cells and their 1 Differentiated Fibroblastic Progenies as Cellular Models for In Vitro Genotoxicity Screening
Project description:This study evaluated human embryonic stem cells (hESC) and their differentiated fibroblastic progenies as cellular models for genotoxicity screening. The DNA damage response of hESCs and their differentiated fibroblastic progenies were compared to a fibroblastic cell line (HEPM, CRL1486) and primary cultures of peripheralblood lymphocytes (PBL), upon exposure to gamma irradiation.
Project description:Validation study of a focused microarray for evaluation of undifferentiated rat ESCs.Using a focused microarray, undifferentiated embryonic stem cells (ESCs) can be distinguished from differentiated ESCs and other cells derived from the early embryo since they have a unique gene expression pattern associated with pluripotency and lack of markers of differentiation. To date, however, such an array has not been developed for the rat species and differences in genomes of rat and human or rat and mouse preclude the use of ESC focused human or mouse microarrays for the rat. Here, we developed a focused microarray for screening rat ESCs and provide validation data that this array can distinguish undifferentiated rat ESCs from rat trophoblast stem cells (TS), rat extraembryonic endoderm cells (XEN), mouse embryonic fibroblast feeder cells (MEFs) and rat ESCs that have been differentiated in vitro. We used this tool to compare rat ESCs which have been expanded in a conventional rat ESC medium containing two inhibitors, e.g., GSK3 and MEK inhibitors, and leukemia inhibitory factor (LIF), and found expression of Cdx2, a gene associated with trophoblast determination. The rat ESC focused microarray described in this report has utility for rapid screening rat ESCs. This will enable optimization of culture conditions in the future. qRT-PCR gene expression profiling of undifferentiated ESCs and iPS cells. Equal amounts (1000ng) total RNA from each cell line was used in independent trials conducted by two investigators, these are technical replicates.
Project description:The lack of accurate in vitro assays for predicting in vivo toxicity of chemicals together with new legislations demanding replacement and reduction of animal testing has triggered the development of alternative methods. This study aimed at developing a transcriptomics-based in vitro prediction assay for in vivo genotoxicity. The transcriptomics changes induced in the human liver cell line HepG2 by 34 compounds after treatment for 12h, 24h and 48h were used for the selection of gene-sets that can discriminate between in vivo genotoxins (GTX) and in vivo non-genotoxins (NGTX). By combining publicly available results for these chemicals from standard in vitro genotoxicity studies with transcriptomics, we developed several prediction models. These models were validated by means of an additional set of 28 chemicals. The study investigated differential gene expression in HepG2 cell line mRNA following 12 hours of exposure to 34 different compounds and their solvents; 24 and 48 hours of exposure to 62 different compounds and their solvents. Three biological replicates per compound/solvent. In total 560 arrays .
Project description:Validation study of a focused microarray for evaluation of undifferentiated rat ESCs.Using a focused microarray, undifferentiated embryonic stem cells (ESCs) can be distinguished from differentiated ESCs and other cells derived from the early embryo since they have a unique gene expression pattern associated with pluripotency and lack of markers of differentiation. To date, however, such an array has not been developed for the rat species and differences in genomes of rat and human or rat and mouse preclude the use of ESC focused human or mouse microarrays for the rat. Here, we developed a focused microarray for screening rat ESCs and provide validation data that this array can distinguish undifferentiated rat ESCs from rat trophoblast stem cells (TS), rat extraembryonic endoderm cells (XEN), mouse embryonic fibroblast feeder cells (MEFs) and rat ESCs that have been differentiated in vitro. We used this tool to compare rat ESCs which have been expanded in a conventional rat ESC medium containing two inhibitors, e.g., GSK3 and MEK inhibitors, and leukemia inhibitory factor (LIF), and found expression of Cdx2, a gene associated with trophoblast determination. The rat ESC focused microarray described in this report has utility for rapid screening rat ESCs. This will enable optimization of culture conditions in the future.
Project description:Validation study of a focused microarray for evaluation of undifferentiated rat ESCs.Using a focused microarray, undifferentiated embryonic stem cells (ESCs) can be distinguished from differentiated ESCs and other cells derived from the early embryo since they have a unique gene expression pattern associated with pluripotency and lack of markers of differentiation. To date, however, such an array has not been developed for the rat species and differences in genomes of rat and human or rat and mouse preclude the use of ESC focused human or mouse microarrays for the rat. Here, we developed a focused microarray for screening rat ESCs and provide validation data that this array can distinguish undifferentiated rat ESCs from rat trophoblast stem cells (TS), rat extraembryonic endoderm cells (XEN), mouse embryonic fibroblast feeder cells (MEFs) and rat ESCs that have been differentiated in vitro. We used this tool to compare rat ESCs which have been expanded in a conventional rat ESC medium containing two inhibitors, e.g., GSK3 and MEK inhibitors, and leukemia inhibitory factor (LIF), and found expression of Cdx2, a gene associated with trophoblast determination. The rat ESC focused microarray described in this report has utility for rapid screening rat ESCs. This will enable optimization of culture conditions in the future.
Project description:The lack of accurate in vitro assays for predicting in vivo toxicity of chemicals together with new legislations demanding replacement and reduction of animal testing has triggered the development of alternative methods. This study aimed at developing a transcriptomics-based in vitro prediction assay for in vivo genotoxicity. The transcriptomics changes induced in the human liver cell line HepG2 by 34 compounds after treatment for 12h, 24h and 48h were used for the selection of gene-sets that can discriminate between in vivo genotoxins (GTX) and in vivo non-genotoxins (NGTX). By combining publicly available results for these chemicals from standard in vitro genotoxicity studies with transcriptomics, we developed several prediction models. These models were validated by means of an additional set of 28 chemicals.
Project description:Sclerotomal progenitors derived from pluripotent stem cells hold promises for modeling skeletal development and recreating embryonic bone microenvironment to restore hematopoiesis and immunity in ageing. Current strategy to derive mouse sclerotomal progenitors suffered from low differentiation efficiency and heterogenous cell progenies. Here, we developed a fast and efficient strategy to generate sclerotomal progenitors from murine embryonic stem cells (mESCs). Naïve mESCs were differentiated through epiblast-like cells (EpiLCs) and primitive streak, and the sclerotomal fate was directly induced from primitive streak by modulating BMP and SHH signaling, achiving an 85.8% differentiation efficiency. Moreover, the resulting progenitors showed similar global gene expression profiles as primary sclerotome, possessed strong osteochondral bipotential and could recapitulate key features of endochondral ossification upon micromass-mediated osteogenic induction, including bone marrow niche regeneration. To investigate the cellular component of the bone marrow derived from scl-progenitors micromass , we performed droplet-based scRNAseq (10X Genomics) of the differentiated bone tissue.
Project description:The conventional battery for genotoxicity testing is not well suited to assessing the large number of chemicals needing evaluation. Traditional in vitro tests lack throughput, provide little mechanistic information, and have poor specificity in predicting in vivo genotoxicity. New Approach Methodologies (NAMs) aim to accelerate the pace of hazard assessment and reduce reliance on in vivo tests that are time-consuming and resource-intensive. As such, high-throughput transcriptomic and flow cytometry-based assays have been developed for modernized in vitro genotoxicity assessment. This includes: the TGx-DDI transcriptomic biomarker (i.e., 64-gene expression signature to identify DNA damage-inducing (DDI) substances), the MicroFlow® assay (i.e., a flow cytometry-based micronucleus (MN) test), and the MultiFlow® assay (i.e., a multiplexed flow cytometry-based reporter assay that yields mode-of-action (MoA) information). The objective of this study was to investigate the utility of the TGx-DDI transcriptomic biomarker, multiplexed with the MicroFlow® and MultiFlow® assays, as an integrated NAM-based testing strategy for screening data-poor compounds prioritized by Health Canada’s New Substances Assessment and Control Bureau. Human lymphoblastoid TK6 cells were exposed to 3 control and 10 data-poor substances, using a 6-point concentration range. Gene expression profiling was conducted using the targeted TempO-SeqTM assay, and the TGx-DDI classifier was applied to the dataset. Classifications were compared with those based on the MicroFlow® and MultiFlow® assays. Benchmark Concentration (BMC) modeling was used for potency ranking. The results of the integrated hazard calls indicate that five of the data-poor compounds were genotoxic in vitro, causing DNA damage via a clastogenic MoA, and one via a pan-genotoxic MoA. Two compounds were likely irrelevant positives in the MN test; two are considered possibly genotoxic causing DNA damage via an ambiguous MoA. BMC modeling revealed nearly identical potency rankings for each assay. This ranking was maintained when all endpoint BMCs were converted into a single score using the Toxicological Prioritization (ToxPi) approach. Overall, this study contributes to the establishment of a modernized approach for effective genotoxicity assessment and chemical prioritization for further regulatory scrutiny. We conclude that the integration of TGx-DDI, MicroFlow®, and MultiFlow® endpoints is an effective NAM-based strategy for genotoxicity assessment of data-poor compounds.
Project description:To follow the changes in the transcriptional programs accompanying the specification, maintenance and differentiation of the adult ISCs we sequenced whole transcriptomes of embryonic intestinal epithelium progenitors (at E12.5 and E14.5), adult ISCs and their differentiated progenies, the majority of which are absorptive enterocytes. EpCAM positive embryonic gut epithelium was isolated from dissected small intestines using fluorescence activated cell sorting (FACS). Adult ISCs were purified on the basis of GFP fluorescence from crypts of Lgr5GFP-Cre-ERT mice (Barker et al. 2007), whereas enterocytes (EpCAM+ CD45- CD31-) were isolated from villi.