Complementary Detection of Embryotoxic Properties of Substances in the Neural and Cardiac Embryonic Stem Cell Tests

In developmental toxicity testing, in vitro screening assays are highly needed to increase efficiency and to reduce animal use. A promising in vitro assay is the cardiac embryonic stem cell test (ESTc), in which the effect of developmental toxicants on cardiomyocyte differentiation is assessed. Recently, we developed a neural differentiation variant of the stem cell test (neural embryonic stem cell test [ESTn]). In both of these models, we have previously performed a series of transcriptomic studies to characterize gene expression changes (1) across time during normal differentiation and (2) in response to a series of developmental toxicants in the ESTn and ESTc. Here, using the cumulative of these studies, we compared gene expression profiles of ESTn and ESTc over time as well as model-specific changes induced by seven compounds, comprising six known in vivo developmental toxicants and one negative control. Time-related gene expression profiles showed similarities between the two EST systems. However, specific genes could be identified changing over time differently in each model related to the two different lineages of differentiation. Interestingly, compound-induced gene expression changes were generally model specific, especially for methylmercury and flusilazole, which were predicted better in ESTn and ESTc, respectively. Valproic acidinduced gene expression changes were most comparable out of the six developmental toxicants between the ESTn and ESTc. Direct transcriptomic comparisons between the ESTn and ESTc indicate that combined transcriptomic analyses support and complement each other. Therefore, a combined approach incorporating ESTc and ESTn may improve developmental toxicant detection over individual assays.