A High-Throughput Screen for Teratogens Using Human Pluripotent Stem Cells

There is need in the pharmaceutical and chemical industries for high-throughput human cell-based assays for identifying hazardous chemicals, thereby reducing the overall reliance on animal studies for predicting the risk of toxic responses in humans. Despite instances of human-specific teratogens such as thalidomide, the use of human cell-teratogenicity assays has just started to be explored. Herein, a human pluripotent stem cell test (hPST) for identifying teratogens is described, benchmarking the in vitro findings to traditional preclinical toxicology teratogenicity studies and when available to teratogenic outcomes in humans. The hPST method employs a 3-day monolayer directed differentiation of human embryonic stem cells. The teratogenic risk of a compound is gauged by measuring the reduction in nuclear translocation of the transcription factor SOX17 in mesendodermal cells. Decreased nuclear SOX17 in the hPST model was strongly correlated with in vivo teratogenicity. Specifically, 71 drug-like compounds with known in vivo effects, including thalidomide, were examined in the hPST. A threshold of 5 μM demonstrated 94% accuracy (97% sensitivity and 92% specificity). Furthermore, 15 environmental toxicants with physicochemical properties distinct from small molecule pharmaceutical agents were examined and a similarly strong concordance with teratogenicity outcomes from in vivo studies was observed. Finally, to assess the suitability of the hPST for high-throughput screens, a small library of 300 kinase inhibitors was tested, demonstrating the hPST platform's utility for interrogating teratogenic mechanisms and drug safety prediction. Thus, the hPST assay is a robust predictor of teratogenicity and appears to be an improvement over existing in vitro models.