Scientists just took a huge step to understand one of the body’s most mysterious organs

Baby embryo egg sperm foetus pregnancy
Doctor is silhouetted as he walks past a poster in a Rome fertility clinic. Alessia Pierdomenico / Reuters

Unlike most organs, the placenta is routinely thrown away.

Yet, like most organs (the appendix being a notable exception), the placenta plays a vital role in the human body.

It’s responsible for mediating exchanges between a mother and the foetus developing inside her uterus, delivering oxygen and nutrients to the foetus and taking away its waste.

The placenta also acts as a barrier, preventing bacteria, viruses, and some medications that could harm the foetus from getting through. When the placenta doesn’t work correctly, it can stunt the foetus’ growth.

But studying this essential, temporary organ in humans is extremely difficult, time-consuming, and possibly risky for the foetus.

Enter the “placenta-on-a-chip,” a small device that replicates how a real placenta works, using actual human cells, so researchers can study the organ in the lab without using animal models. An international team of researchers developed a prototype and published the details June 18 in the Journal of Maternal-Fetal and Neonatal Medicine.

How it works

The placenta-on-a-chip has two tiny chambers, separated by a membrane that lets some but not all molecules cross it. To mimic the interface between the mother and foetus, one chamber has maternal cells extracted from a delivered placenta, and the other has fetal cells taken from an umbilical cord.

Placenta chip
A schematic of the placenta-on-a-chip. The upper channel gets fetal cells and the lower channel gets maternal cells. Lee et al.

With this double layer of tissue resembling the part of the placenta where mother and foetus meet, the researchers performed a test to see whether it worked similarly to the placentas of sheep, which had been used as an earlier (costlier) model for research.

They put glucose, a key source of energy for the body, in the chamber with maternal cells and measured how it got to the other chamber with fetal cells. The transfer happened pretty much like it did in the sheep, so the researchers concluded the placenta-on-a-chip works like the full size one in the body, at least in this respect.

The placenta-on-a-chip gives scientists a handy little model to study what the Eunice Kennedy Shriver National Institute of Child Health and Human Development called “the least understood human organ.”

“The chip may allow us to do experiments more efficiently and at a lower cost than animal studies,” Dr. Roberto Romero, one of the study authors said in a statement. “With further improvements, we hope this technology may lead to better understanding of normal placental processes and placental disorders.”

If improvements to the device can make it a truly usable model for studying the placenta, such research will be safer and more doable across the board — and that means scientists can finally begin to peel back the mystery of this essential, routinely discarded organ.

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