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Development of an In Vitro Human Thyroid Microtissue Model for Chemical Screening (ToxSci)
Citation:
Deisenroth, C., V. Soldatow, J. Ford, W. Stewart, C. Brinkman, E. LeCluyse, D. Macmillan, AND R. Thomas. Development of an In Vitro Human Thyroid Microtissue Model for Chemical Screening (ToxSci). TOXICOLOGICAL SCIENCES. Society of Toxicology, RESTON, VA, 174(1):63-78, (2020). https://doi.org/10.1093/toxsci/kfz238
Impact/Purpose:
The US EPA Endocrine Disruptor Screening Program (EDSP) has identified several molecular thyroid targets relevant to hormone synthesis dynamics that have been adapted to high-throughput screening (HTS) assays to rapidly evaluate the ToxCast/Tox21 chemical inventories for potential thyroid disrupting chemicals (TDCs). A limitation to these target-based approaches is the uncertainty in predicting tissue-level functional effects on thyroid hormone production in a manner that is more physiologically relevant and analogous to endpoints evaluated in existing guideline studies. The objective of this study was to develop a medium-throughput organotypic screening assay comprised of reconstructed human thyroid microtissues to quantitatively evaluate the disruptive effects of chemicals on TH production and secretion. Implementation of the assay may prove useful for interpreting phenotypic effects of candidate TDCs identified by HTS efforts currently underway in the EDSP.
Description:
Thyroid hormones (TH) are essential for regulating a number of diverse physiological processes required for normal growth, development, and metabolism. The US EPA Endocrine Disruptor Screening Program (EDSP) has identified several molecular thyroid targets relevant to hormone synthesis dynamics that have been adapted to high-throughput screening (HTS) assays to rapidly evaluate the ToxCast/Tox21 chemical inventories for potential thyroid disrupting chemicals (TDCs). The uncertainty surrounding the specificity of active chemicals identified in these screens and the relevance to phenotypic effects on in vivo human TH synthesis are notable data gaps for hazard identification of TDCs. The objective of this study was to develop a medium-throughput organotypic screening assay comprised of reconstructed human thyroid microtissues to quantitatively evaluate the disruptive effects of chemicals on TH production and secretion. Primary human thyroid cells procured from qualified euthyroid donors were analyzed for retention of NK2 homeobox 1 (NKX2-1), Keratin 7 (KRT7), and Thyroglobulin (TG) expression by high-content image analysis to verify enrichment of follicular epithelial cells. A direct comparison of two-dimensional (2D) and three-dimensional (3D) 96-well culture formats was employed to characterize the morphology, differential gene expression, TG production, and TH synthesis over the course of 20 days. The results indicate that modeling human thyroid cells in the 3D format was sufficient to restore TH synthesis not observed in the 2D culture format. Inhibition of TH synthesis in an optimized 3D culture format was demonstrated with reference chemicals for key molecular targets within the thyroid gland. Implementation of the assay may prove useful for interpreting phenotypic effects of candidate TDCs identified by HTS efforts currently underway in the EDSP.
URLs/Downloads:
DOI: Development of an In Vitro Human Thyroid Microtissue Model for Chemical Screening (ToxSci)
DEISENROTH_THYROID MICROTISSUE MODEL FINAL.PDF (PDF, NA pp, 1156.063 KB, about PDF)
https://pubmed.ncbi.nlm.nih.gov/31808822/