Studies shine light on placenta, how it goes awry

WASHINGTON -- Scientists carefully probe a placenta donated after birth, bluish umbilical cord still attached. This is the body's most mysterious organ, and inside lie clues to how this giver of life forms -- and how it can go awry, leading to stillbirth, preterm birth, even infections such as the Zika virus that somehow sneak past its protective barrier.

In labs around the country, major research is underway to understand and monitor this floppy, bloody tissue that's often dismissed as the "afterbirth," the organ that lives about nine months and then gets thrown away.

The stakes are high.

The placenta is the ultimate multitasker: It nourishes a fetus, acts as its lungs, kidneys and liver, provides immune defense and even produces key hormones.

"We take it for granted," said Dr. Catherine Spong of the National Institutes of Health, which has spurred a research boom with its $50 million Human Placenta Project. "Yet there are lifelong implications for both the mother and the baby."

Zika's shocking birth defects have brought into focus the need to learn how a healthy placenta does its many jobs and find treatments for when it is undermined.

"Tomorrow there may be a new virus," warned Dr. Yoel Sadovsky of the University of Pittsburgh Medical Center, a leading placenta researcher. "If I was a virus and wanted to attack humans, probably the best time to do it was during pregnancy, where you're attacking the next generation."

Doctors have few tools today to examine a placenta during pregnancy. And precious as that donated placenta is for research, studying one that already ushered in a birth reveals only so much, like counting the rings in a downed tree to visualize the sapling.

What scientists and obstetricians really need is a way to peek at how the placenta forms and changes during the different stages of pregnancy.

That could help spot problems early -- such as pre-eclampsia, a blood-pressure complication that can be life-threatening to mother and baby.

It affects up to 8 percent of pregnancies but typically isn't detected until the second trimester, even though it's thought to stem from abnormal placenta formation.

How? In a Washington lab, engineer Avinash Eranki turns over the donated placenta, examining the side that attached to the mother.

That outer layer is made up of cells called trophoblasts that had to invade the uterine wall and then burrow into maternal arteries, enlarging them to provide blood flow for the fetus.

The theory: If those cells get off course and the blood vessels don't widen enough, the downstream effects of a placenta struggling to support the fetus eventually stress the mother's own organs.

The research team at Children's National Health System is using a 3-D bioprinter to create a unique living model of how a human placenta forms, to mimic how trophoblasts create that blood supply.

The printer deposits layer after layer of human cells and other substances they need to thrive.

Once it's complete, the model could help researchers test ways to detect brewing pre-eclampsia earlier and intervene. Today, the only cure for severe cases is premature delivery of the baby.

At the NIH, researchers are targeting another critical gap: It's hard to tell how much oxygen is reaching the fetus.

Biomedical engineer Afrouz Anderson of the National Institute of Child Health and Human Development is developing a wireless device, called an oximeter, that uses near-infrared light to measure placental oxygen when held over a mother's abdomen.

Anderson, who is testing the device in a model that mimics blood flowing through a placenta, sees its potential use during preeclampsia or when the fetus isn't growing properly.

In a study planned for early next year, she'll team with military doctors to measure what's normal in healthy pregnant women.

"My biggest hope is if the oxygenation status would give a more accurate picture," so that "we don't have to go do a C-section because the baby's actually happy," said Dr. Shad Deering, obstetrics chairman at the Uniformed Services University of the Health Sciences.