Toxicity testing on the placenta and embryo

Drugs must be safe not just for the patients; in the case of pregnant patients, drugs must also be safe for the unborn children still in the womb. Therefore, at an early stage in the development of new medicines, candidate substances are tested in the Petri dish on embryonic stem cells from mouse cell lines. This is to avoid that an embryo-​damaging effect would only be noticed at a later stage during tests with pregnant mice.

However, these cell culture tests are a highly simplified version of what takes place in the uterus. Researchers just add the test material to a culture of embryonic stem cells in a Petri dish, and can identify substances that have a direct adverse effect on embryonic cells. By contrast, in the body of a pregnant woman, active pharmaceutical ingredients may be modified by the mother’s metabolism and enter the embryo’s bloodstream via the placenta. Moreover, standard cell culture tests can’t detect substances that have indirect effects on the embryo, for example, in that they interfere with the functioning of the placenta or generate stress responses.

Researchers in the Department of Biosystems Science and Engineering at ETH Zurich in Basel have now devised a laboratory test that incorporates the role of the placenta into embryotoxicity assessments. To do so, Julia Boos, a doctoral student in the group of ETH Professor Andreas Hierlemann, and her colleagues developed a new chip.