Use ofIn VitroMorphogenesis of Mouse Embryoid Bodies to Assess Developmental Toxicity of Therapeutic Drugs Contraindicated in Pregnancy

In utero exposure to certain chemicals can impair embryo development, causing embryonic death, growth retardation, or severe birth defects. Establishment of effective in vitro tests is crucial for identifying developmental toxicants and for reducing the financial and ethical burden of animal-based tests. Previously, we created an in vitro morphogenesis model using pluripotent P19C5 mouse embryonal carcinoma stem cells that mimics the process of gastrulation and axial body elongation of embryos. Because many birth defects are caused by dysregulation of cellular behaviors during embryogenesis, the morphogenesis model may serve as a unique tool to investigate the impacts of developmental toxicants. The aim of this study is to evaluate the applicability and limitations of the model using 20 therapeutic drugs, 16 of which are contraindicated in pregnancy and 4 are considered safe. P19C5 embryoid bodies (EBs) were exposed to different concentrations of drugs during 4 days of 3-dimensional culture. The treatment effects on growth and morphogenesis were analyzed using morphometric measurements of EB size and shape, respectively. Viability assays of P19C5 cells and NIH/3T3 fibroblasts were used to determine the drug concentrations that caused general cytotoxicity and those that selectively diminished P19C5 proliferation relative to NIH/3T3 proliferation. Thirteen contraindicated drugs diminished P19C5 cell proliferation, reduced EB growth, or altered morphogenesis at concentrations below generally cytotoxic levels. Two safe drugs also exhibited these impacts at the highest concentration tested. Although additional validation studies are required, this study introduces morphogenesis-based stem cell models as potentially effective in vitro tools for developmental toxicity research.