Use of the ES-D3 cell differentiation assay, combined with the BeWo transport model, to predict relative in vivo developmental toxicity of antifungal compounds

• In vitro developmental toxicity of five antifungal compounds was investigated.
• ES-D3 cell differentiation assay was used to predict developmental toxicity.
• The BeWo transport model was used for the characterization of placental transfer.
• Transport rates across in vitro placental barrier were different among compounds.
• ES-D3 cell differentiation assay, combined with BeWo model, increased predictivity.

We investigated the applicability of the ES-D3 cell differentiation assay combined with the in vitro BeWo transport model to predict the relative in vivo developmental toxicity potencies. To this purpose, the in vitro developmental toxicity of five antifungal compounds was investigated by characterizing their inhibitory effect on the differentiation of ES-D3 cells into cardiomyocytes. The BeWo transport model, consisting of BeWo b30 cells grown on transwell inserts and mimicking the placental barrier, was used to determine the relative placental transport velocity. The ES-D3 cell differentiation data were first compared to benchmark doses (BMDs) for in vivo developmental toxicity as derived from data reported in the literature. Correlation between the benchmark concentration for 50% effect (BMCd50) values, obtained in the ES-D3 cell differentiation assay, with in vivo BMD10 values showed a reasonable correlation (R2 = 0.57). When the ES-D3 cell differentiation data were combined with the relative transport rates obtained from the BeWo model, the correlation with the in vivo data increased (R2 = 0.95). In conclusion, we show that the ES-D3 cell differentiation assay is able to better predict the in vivo developmental toxicity ranking of antifungal compounds when combined with the BeWo transport model, than as a stand-alone assay.