title: Assaying embryotoxicity in the test tube: current limitations of the embryonic stem cell test (EST) challenging its applicability domain.
abstract: Testing for embryotoxicity in vitro is an attractive alternative to animal experimentation. The embryonic stem cell test (EST) is such a method, and it has been formally validated by the European Centre for the Validation of Alternative Methods. A number of recent studies have underscored the potential of this method. However, the EST performed well below the 78% accuracy expected from the validation study using a new set of chemicals and pharmaceutical compounds, and also of toxicity criteria, tested to enlarge the database of the validated EST as part of the Work Package III of the ReProTect Project funded within the 6th Framework Programme of the European Union. To assess the performance and applicability domain of the EST we present a detailed review of the substances and their effects in the EST being nitrofen, ochratoxin A, D-penicillamine, methylazoxymethanol, lovastatin, papaverine, warfarin, β-aminopropionitrile, dinoseb, furosemide, doxylamine, pravastatin, and metoclopramide. By delineation of the molecular mechanisms of the substances we identify six categories of reasons for misclassifications. Some of these limitations might also affect other in vitro methods assessing embryotoxicity. Substances that fall into these categories need to be included in future validation sets and in validation guidelines for embryotoxicity testing. Most importantly, we suggest conceivable improvements and additions to the EST which will resolve most of the limitations.
authors.affiliation: German Federal Institute for Risk Assessment (BfR), ZEBET - Alternative Methods to Animal Experiments, Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Riebeling
authors.forename: Katrin
authors.initials: K
authors.lastname: Hayess
authors.forename: Annelieke K
authors.initials: AK
authors.lastname: Peters
authors.forename: Margino
authors.initials: M
authors.lastname: Steemans
authors.forename: Horst
authors.initials: H
authors.lastname: Spielmann
authors.forename: Andreas
authors.initials: A
authors.lastname: Luch
authors.forename: Andrea E M
authors.initials: AE
authors.lastname: Seiler
mesh_terms: D000826:Animal Testing Alternatives / Q000379:methods*; D000818:Animals; D004622:Embryo, Mammalian / Q000187:drug effects*; D053595:Embryonic Stem Cells / Q000187:drug effects*; D005060:Europe; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013723:Teratogens / Q000145:classification / Q000633:toxicity*; D015262:Xenobiotics / Q000145:classification / Q000633:toxicity*
chemical_list: D013723:Teratogens; D015262:Xenobiotics