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Fetuses give mothers a gift of cells, study says

Many a pregnant woman has moments when her fetus seems like a little parasite, all take, take, take. But new research suggests that a fetus may also be giving back a lifelong gift: cells that appear to act like stem cells, migrating to diseased organs in the mother and trying to fix them.

Tufts-New England Medical Center researchers report in today's Journal of the American Medical Association that they have found evidence of such transformed fetal cells in the livers, thyroids, and spleens of women who have been pregnant.

"If we can prove these are stem cells, and harvest them from the blood or tissue of a woman who's been pregnant, they could have therapeutic potential for that woman, her children, and perhaps even unrelated individuals," said Dr. Diana Bianchi, chief of medical genetics at the hospital and senior author on the paper.

The findings could also affect the national debate over stem cells, she said, in that they raise the possibility of obtaining stem cells, which can change into many tissues of the body, without the ethical issues involved in creating or destroying human embryos. President Bush has sharply restricted federal funding for research on human embryonic stem cells to keep the government from supporting research that he believes destroys human life.

In an editorial, the AMA journal said the work raised "novel and exciting" possibilities, and added: "The time may soon come when the prenatal child heals the mother and perhaps in the far distant future becomes the ultimate health insurance for the whole family."

Back in 1996, Bianchi was the first researcher to show that fetal cells persist and could be detected in the blood of women who had been pregnant. They appear in tiny quantities -- perhaps 5 cells in a whole teaspoon of blood -- but seem to remain forever in the blood of such women, including those who miscarry or abort.

Since then, Bianchi and other researchers have found such fetal cells in various organs, but they have always taken the form of blood cells.

This new paper, she said, is the first report that researchers have found fetal cells that bore the markers of other types of cells. The cells resembled those in the organs where they were found -- the liver, spleen, and thyroid. And they appeared disproportionately in diseased organs.

The work is still preliminary. More research is needed to clearly show that the fetal cells are stem cells and, if they are, to find ways to use them to treat diseases, Bianchi said.

It has long been thought that women who have been pregnant are likelier to develop autoimmune diseases such as scleroderma and lupus, in which the body attacks its own organs. Since the discovery that fetal cells keep circulating in the mother's system, some have theorized that they could be the culprits, inciting an overreaction in the body.

But this latest research, Bianchi said, suggests "an alternate hypothesis: that maybe the fetal cells actually had some characteristics of stem cells and were capable of responding to injury or remodeling the mother's organs. And maybe it was a good thing."

One thing appears certain, she said: "Pregnancy lasts a lifetime, and you carry mementos of your children wherever you go."

Carey Goldberg can be reached at

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