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Characterizing Developmental Toxicity Through Pluripotent Embryonic Stem Cell Assays and the ToxCast Library
Citation:
Zurlinden, T., K. Saili, S. Hunter, N. Baker, AND T. Knudsen. Characterizing Developmental Toxicity Through Pluripotent Embryonic Stem Cell Assays and the ToxCast Library. Presented at SOT Annual Meeting, Baltimore, MD, March 10 - 14, 2019. https://doi.org/10.23645/epacomptox.7844885
Impact/Purpose:
To utilize pluripotent stem cells, in conjunction with high throughput screening technologies, to aid in developmental hazard prioritization for large numbers of chemicals. To investigate this potential, ToxCast chemicals were profiled for developmental toxicity in two embryonic stem cell assays: the devTOX quickPredict platform from Stemina (STM) utilizing a human pluripotent H9 stem cell-based assay; and the mouse embryonic stem cell (mESC) adherent assay.
Description:
Predicting and characterizing potential human teratogenic compounds remains a challenge as toxicology moves towards new approach methods (NAMs) for hazard identification with animal models remaining the ‘gold’ standard for assessing developmental toxicity in humans. Utilizing pluripotent stem cells, in conjunction with high throughput screening technologies, has the potential to aid in developmental hazard prioritization for large numbers of chemicals and lessen the strict reliance on costly and time-consuming animal methods. To investigate this potential, ToxCast chemicals were profiled for developmental toxicity in two embryonic stem cell assays: the devTOX quickPredict platform from Stemina (STM) utilizing a human pluripotent H9 stem cell-based assay; and the mouse embryonic stem cell (mESC) adherent assay. This involved a comparison of the STM platform to two sets of compounds to test model performance: A benchmark set of 42 compounds (BM42), of which 26 are classified as developmental toxicants and a set of 432 ToxRefDB compounds (TR432), of which 187 showed evidence of developmental toxicity from prenatal rat and rabbit developmental toxicity tests (lowest effect level ≤200 mg/kg/day). When compared against the BM42 set, the STM platform had a model performance of 78.5% accuracy (0.65 sensitivity, 1.0 specificity, 0.79 f1) and against the TR432 compounds, had a model performance of 61.3% accuracy (0.31 sensitivity, 0.84 specificity, 0.41 f1). Using the mESC adherent assay, we screened a subset of 214 chemicals from the TR432 compound set and found a model performance for the STM platform of 84% accuracy with 89 (42% tested) predicted putative developmental toxicants. To characterize biological pathways associated with hits in the STM platform and to investigate utilizing pathway-based predictions of developmental toxicity, 337 enzymatic and receptor signaling assays in the ToxCast NovaScreen dataset (NVS) were trained on the STM hit call data to determine gene associations with STM positive and STM negative responses. Gene annotations and weighting scores for NVS targets were imported to the Reactome HSA Pathway Browser (v3.5, database release 63) to further characterize the sensitive and insensitive biochemical domains. For example, BRAF signaling was in the sensitive domain whereas estrogen signaling the insensitive domain. When the mESC response was mined against ToxCast assay targets, those correlating with developmental toxicity included TP53, RXRB, SLC18A2, CYP3A4 whereas CD38, CHRNA7, IL8 were not correlated with the mESC response. By including the chemical perturbation of each NVS-derived pathway, in conjunction with the STM platform, model accuracy against the BM42 set increased to 83.3% (0.77 sens, 0.88 spec, 0.83 f1) while accuracy against the TR432 set was 60% (0.55 sens, 0.64 spec, 0.54 f1). These findings set the stage for identifying and developing new approach methodologies based on in vitro data and in silico models for prenatal developmental toxicity. [This abstract may not reflect US EPA policy].
URLs/Downloads:
DOI: Characterizing Developmental Toxicity Through Pluripotent Embryonic Stem Cell Assays and the ToxCast Library
SOT_STM_ZURLINDEN_FINAL_M.PDF (PDF, NA pp, 1380.065 KB, about PDF)