Fetal Cells May Protect Mom From Disease Long After The Baby's Born | KUOW News and Information

Fetal Cells May Protect Mom From Disease Long After The Baby's Born

Oct 26, 2015
Originally published on October 27, 2015 1:36 pm

This is a story about two people sharing one body. Maybe even three people. Or four.

Back in the late 19th century, a German scientist named Georg Schmorl made a remarkable discovery: Cells from a baby can hide out in a mother's body, after birth.

More than a hundred years later, scientists are just beginning to figure out what these cells are doing. And their findings may have implications for how cancer and autoimmune diseases affect women.

But the discovery also means something else. Something that's a bit mind-boggling: You likely have cells from your older siblings in your body. And cells from your grandmother, maybe even your great-grandmother.

Here's how.

Pregnancy has every element of an alien invasion, says Dr. Hilary Gammill, a fetal medicine expert at the University of Washington in Seattle.

The fetus has different genes than the mom. So in a sense, she's a foreigner inside the mom's body. And the placenta literally invades the mother's body, Gammill says.

As the placenta grows, it reaches out and grabs onto the mom's arteries to control blood flow. "The human placenta is one of the most invasive placentas," compared to those in other animals, Gammill says.

This ensures the fetus has nutrients. But in the process the baby ends up giving the mother a gift. "There's a very large amount of fetal material that is sloughed off into the mother's circulation," says Dr. J. Lee Nelson, also at the University of Washington. "This material is widely circulating in the mom's body."

Nelson has been studying this rogue fetal material for more than 20 years. It contains DNA from the fetus, tiny pieces of the placenta and potent fetal cells. They travel around the mom's bloodstream and sneak into her organs.

"They can go to the liver and become liver cells, or go into the heart and become muscle cells," Nelson says. Fetal cells can even cross the blood-brain barrier and turn into neurons.

When scientists first started studying fetal cells in mothers, the cells got a bad reputation. They have been linked to preeclampsia and autoimmune diseases, such as scleroderma.

But, as time went on, more studies began to suggest that in some situations fetal cells can be beneficial to moms, Nelson says. "I think you've got to think of these cells as friends," she says.

Scientists have found fetal cells in scar tissues, specifically scars left by C-sections. These cells make collagen. So the fetus could be helping the mom recover after birth by repairing wounds.

Fetal cells also are linked to an overall reduced risk of rheumatoid arthritis and are thought to protect against breast cancer.

One hypothesis is that fetal cells may act like little sentinels, watching out for breast cancer cells and killing them. "We haven't caught them in the act yet to say for sure that's what they are doing," Gammill says. But some studies suggest this could be the case.

For autoimmune diseases, the baby's genes likely determine whether the fetal cells are friends or foes, Nelson says. Specifically, if a gene involved in immune recognition matches too closely to the mom's genes, the cells could trigger autoimmunity. But otherwise, they may be protective.

"Being an optimist, I think the benefits will outweigh the times when they're problematical," Nelson says. "So it's actually a beautiful cooperation."

And it's not just the mom that gets an extra set of cells.

"We've been talking about a very one-sided story. ... This is a bidirectional process," says Amy Boddy, a postdoctoral fellow at Arizona State University who recently wrote a review on this topic.

"Cells from the mom also cross the placenta and enter the fetal body," Boddy says. And that means you've got your mom's cells inside you.

But it also means you're likely closer to your older brother or sister than you might think.

Since your mom had cells in her body from all her other pregnancies and her mom, that means you likely have cells from your older siblings, and from your grandmother, and maybe even your great-grandmother.

"You can keep going up the family tree pretty far," Boddy says.

So far, scientists haven't actually seen these "grandma cells" in anyone's body. But if they do exist, then it means we are all walking around with a whole family tree inside of us.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

DAVID GREENE, HOST:

A story about two people sharing one body - maybe even three people. A baby's cells can hide out in a mother's body after birth. A German scientist found this out back in the 1800s, and now scientists are trying to figure out what these cells are doing. NPR's Michaeleen Doucleff reports these findings could have implications for cancer and immune system diseases.

MICHAELEEN DOUCLEFF, BYLINE: When I announced at work that I was pregnant, I got this response from my colleague, NPR's Laura Sydell.

LAURA SYDELL: Oh, wow, it's like an alien invaded your body.

DOUCLEFF: OK, I knew that was a joke. But as the months went on, I started wondering if it's true. Has an alien really invaded my body? So I called up Hilary Gammill, an OB/GYN at the University of Washington, and asked her.

HILARY GAMMILL: (Laughter) That's an interesting question. Well, so I guess you could say that (laughter). It's not the way we typically would think about things.

DOUCLEFF: Gammill is a leading expert in fetal medicine. She says pregnancy does have all the elements of an alien invasion. She says the baby's genes are different than mine, so in a sense, she's a foreigner. And when the placenta grows, it actually invades the mom's body.

GAMMILL: The human placenta is one of the most invasive placentas. So I guess you could say that there's invasion happening.

DOUCLEFF: The placenta reaches out and grabs onto the mom's arteries to control blood flow. This ensures the fetus has nutrients. But in the process...

J. LEE NELSON: There's a very large amount of fetal material that is sloughed into the mother's circulation, especially in the third trimester. I mean, it's widely circulated throughout the mother's body.

DOUCLEFF: That's J. Lee Nelson, also at the University of Washington. She has been studying this rogue fetal material for more than 20 years. It contains DNA, pieces of the placenta and potent fetal cells. They travel around the mom's bloodstream and sneak into the mother's organs.

GAMMILL: They can be in the liver, and they can become, for example, a liver cell - or in the heart, where they can become a muscle cell.

DOUCLEFF: So the fetus is integrating itself into the mom's body. These cells are also found in the mom's scar tissue, specifically scars of C-sections. So scientists think these cells can help moms recover after giving birth by helping to repair wounds. Nelson says fetal cells can also go into the mom's brain and turn into neurons.

Then the fetus could be actually controlling your mind through these neurons?

NELSON: Well, that's a bit of a jump (laughter). I think we have a connotation with alien that's not necessarily positive. But I think you've got to consider them as friends.

DOUCLEFF: These cells got a bad reputation when scientists first started studying them. They have been linked to immune system diseases and preeclampsia, a deadly complication during pregnancy. But Nelson says as time went on, more studies began to suggest fetal cells are beneficial to moms. They're linked to a reduced risk of rheumatoid arthritis and thought to protect against breast cancer. One hypothesis is that fetal cells may act like little sentinels, watching out for breast cancer cells and killing them.

NELSON: Being an optimist, I think that the benefits outweigh the times when they're problematical. So it's actually kind a beautiful cooperation.

DOUCLEFF: And it's not just the moms that get an extra set of cells. Amy Boddy is an evolutionary biologist at Arizona State University. She and her colleagues recently wrote a review on this topic.

AMY BODDY: We've been talking on a very one-sided story. But this is a bidirectional transfer of cells. Cells from the mother also cross the placenta and enter the fetal body.

DOUCLEFF: Which, if you think about it, means you've got your mom's cells inside you. But it also means something else, something that's a bit mind-boggling. Since your mom had cells in her body from all her other pregnancies and her mom, that means you likely have cells from your older siblings and from your grandmother, maybe even your great-grandmother.

BODDY: You can keep going up the family tree pretty far.

DOUCLEFF: So far, scientists haven't actually seen these grandma cells in anyone's body. But if they do exist, it means we're all walking around with a whole family tree inside of us. Michaeleen Doucleff, NPR News. Transcript provided by NPR, Copyright NPR.