Researchers in Japan have set a course to better understand the human placenta by deriving and growing placenta stem cells for the first time, in the goal of better understanding the difference between healthy and complicated pregnancies.

“Trophoblast cells play an essential role in the interactions between the fetus and mother,” writes Takahiro Arima, a professor of informative genetics at the Tohoku University School of Medicine in Japan and lead author of the study published in the journal Cell Stem Cell. Trophoblast cells form the outer layer of the fertilized egg. As the fertilized egg develops into an embryo, and then into a fetus, the layer develops into the placenta, the uterine lining that provides nutrients to the fetus and removes its waste.

Too few or too many trophoblast cells can mean complications for the fetus and mother. An imbalance of trophoblast cells can lead to miscarriage in early pregnancy, or preeclampsia and other conditions later on. Preeclampsia, which affects roughly 8 to 10% of pregnant women in India, is a condition in which pregnant women, who have previously had normal blood pressure, develop hypertension, retain fluids, and experience swelling in their extremities; undiagnosed, it can develop into the more serious and life-threatening version, eclampsia.

That is why it is important to study human trophoblast development and function, Arima explains. Growing trophoblast cells in a laboratory environment will let scientists to do that, without risk to any developing embryos or pregnant women.

The research team derived trophoblast cells from human volunteers with approval from the Ethics Committee of Tohoku University School of Medicine. The cells were then transferred to a growth medium to proliferate, but the cells died off.

Using genetic sequencing, Arima and his research team found that the cells needed certain proteins activated and others inhibited to stay alive and maintain the same characteristics they would have in utero. The result is a line of placenta stem cells independent of a fertilized egg upon which researchers can now experiment to identify the causes and develop treatments for a variety of pregnancy complications and conditions.