Editor's Highlight: Development of Novel Neural Embryonic Stem CellTests for High-Throughput Screening of Embryotoxic Chemicals.

There is a great demand for appropriate alternative methods to rapidly evaluate the developmental and reproductive toxicity of a wide variety of chemicals. We used the differentiation of mouse embryonic stem cells (mESCs) into cardiomyocytes as a basis for establishing a rapid and highly reproducible invitro embryotoxicity test known as the Hand1-Luc Embryonic Stem Cell Test (Hand1-Luc EST). In this study, we developed novel neural-Luc ESTs using two marker genes for neural development, tubulin beta-3 (Tubb3) and Reelin (Reln), and evaluated the capacity of these tests to predict developmental toxicity. In addition, we tested whether an integrated approach (a combination of neural-Luc ESTs and the Hand1-Luc EST) improved developmental toxicant detection. To perform our neural-Luc ESTs, we needed to generate stable transgenic mESCs with individual promoters linked to the luciferase gene, and to establish that similar changes in promoter activities and mRNA expression levels occur during neural differentiation. Based on the concentration-response curves of 15 developmental toxicants and 17 non-developmental toxic chemicals, we derived a prediction formula and assessed the capacity of this formula to predict developmental toxicity. Although both were highly sensitive and specific for predicting developmental toxicity, neural-Luc ESTs had similar predictive capacities. In contrast, neural-Luc ESTs and Hand1-Luc EST had significantly different predictive powers. As expected, the combination of these ESTs increased the sensitivity of developmental toxicant detection. These results demonstrate the convenience and the usefulness of this combination of ESTs as an alternative assay system for future toxicological and mechanistic studies of developmental toxicity.