A bioengineered model of human placental exposure to environmental metals during pregnancy

Exposure of pregnant women to toxic metals is an environmental health issue associated with various pregnancy complications. Efforts to advance our biological understanding of this problem and mitigate its adverse effects, however, have been challenged by ethical concerns of human subject research during pregnancy. Here, we present an alternative approach that leverages the design flexibility, controllability, and scalability of bioengineered human reproductive tissues to enable experimental simulation and in-depth investigation of placental exposure to environmental metals in maternal circulation. Central to this method is an in vitro analog of the maternal-fetal interface and its dynamic tissue-specific environment constructed using primary human placental cells grown in a microengineered device. Using cadmium as a representative toxicant, we demonstrate the proof-of-concept of emulating the human placental barrier subjected to the flow of cadmium-containing maternal blood to show how this model can be used to examine adverse biological responses and impaired tissue function on both the maternal and fetal sides. Moreover, we present a mechanistic study of maternal-to-fetal cadmium transport in this system to reveal that efflux membrane transporters expressed by trophoblasts may play an important protective role against cadmium-induced toxicity. Finally, we describe metabolomic analysis of our microphysiological system to demonstrate the feasibility of discovering metabolic biomarkers that may potentially be useful for detection and monitoring of cadmium-induced placental dysfunction.