Development and characterisation of a new model of rat trophoblasts

The placenta plays a key role during pregnancy. In vitro models have proven to assess the role of placental transporters in the exchange of nutrients, waste products and the distribution of drugs between the maternal and fetal compartments. Therefore, a primoculture of Wistar rat trophoblasts from the labyrinth zone was developed and characterised. Expression of placental transporters including P-glycoprotein (P-gp) and bcrp was evaluated by western blot and their activity using different inhibitors. A time-dependent increase in P-gp expression was noted from primocultures Day 2 to Day 4 followed by a plateau thereafter, whereas bcrp expression was stable throughout the culture period. P-gp and bcrp expression was maintained after seven passages in primocultures and in cryopreserved trophoblasts (up to 3 freezings and 10 passages). Activity of efflux transporters was confirmed in both placental primocultures and cryopreserved trophoblasts by an approximately 60% inhibition with cyclosporin A and valspodar for P-gp and 55% with elacridar for bcrp. In sum, this new in vitro model seems promising for a better understanding of the role of P-gp and bcrp in the toxicity of drugs during pregnancy and could be considered as an additional step towards the minimization of animal testing during drug development.