In Vitro Approaches to Evaluate Placental Drug Transport by Using Differentiating JEG-3 Human Choriocarcinoma Cells

Human choriocarcinoma cells have been used as models for studying transcellular drug transport through placental trophoblasts. However, these models allow the transport of low-molecular-weight drugs through intercellular gap junctions. This study aimed at investigating the differentiation patterns of JEG-3 choriocarcinoma cells under different culture conditions and establishing the appropriate model of in vitro syncytiotrophoblast drug transport. Paracellular permeability was estimated by measuring the transepithelial electrical resistance (TEER) across JEG-3 cell layers. The mRNA expression levels of non-expressed in choriocarcinoma clone 1 (NECC1) and breast cancer resistance protein (BCRP), and those of E-cadherin (ECAD) and cadherin-11 (CDH11), which are adherens junction-associated proteins related to fusogenic ability of syncytiotrophoblasts differentiated from cytotrophoblasts, protein expression levels were considered as the differentiation signals. The highest TEER values were obtained in the JEG-3 cells cultured in the Dulbecco's modified Eagle's medium (DMEM)/Ham's F-12 (1:1) mixed medium (CS-C (R); Dainippon Sumitomo Pharma Co. Ltd., Osaka, Japan). By comparing the TEER values and the differentiation signals, the authors identified at least five JEG-3 cell-differentiation patterns. The differentiation pattern of JEG-3 cultured in CS-C resembled the syncytiotrophoblast-like differentiation signal characterizations in vivo. In conclusion, the syncytiotrophoblast-like models of differentiating JEG-3 cells cultured in CS-C might be appropriate for evaluating drug transport across the placental trophoblast.