Scientists Claim to Find Cells That Restore Egg Production

By Rob Stein
Washington Post Staff Writer
Thursday, July 28, 2005

A team of Harvard scientists is claiming the discovery of a reservoir of cells that appear capable of replenishing the ovaries of sterilized mice, possibly providing new ways to help infertile women have babies.

While cautioning that more research is needed to confirm that similar cells exist in women and that they can safely restore fertility, the researchers said the findings could revolutionize the understanding of female reproduction and the power to manipulate it.

"This may launch a new era in how to think about female infertility and menopause," said Jonathan L. Tilly, a reproductive biologist at Harvard Medical School and Massachusetts General Hospital in Boston who led the research. It is being published in tomorrow's issue of the journal Cell.

Other researchers agreed that the findings could have profound implications, but several expressed caution and skepticism, saying many key questions remain about whether the researchers have proved their claims.

"This is really exciting and a revolutionary idea. The implications are potentially huge," said Lawrence Nelson of the National Institute of Child Health and Human Development. "But before this could have any type of application to humans, a whole lot of work has to be done. We have to be careful not to get ahead of ourselves."

But Tilly said he was confident of his findings, which could, for example, enable women to bank egg-producing cells when they are young in case they have health problems that leave them infertile or they get too old.

"In theory, these cells could provide an insurance policy. We could harvest them and store them away for 20 years. Then you put them back in, and they are going to do exactly what they are supposed to -- find the ovaries and generate new eggs" to restore fertility, Tilly said.

The discovery could also lead to ways to prevent, delay or reverse menopause, perhaps by stimulating dormant cells in the bone marrow or "tweaking" the ovaries to accept them, Tilly said. It may also be possible to transplant them from one woman to another, he said.

In addition, because the cells appear to be a particularly versatile type of adult stem cell, they could provide an alternative to those obtained from embryos, avoiding the political and ethical debates raging around the use of those cells.

"The implications are mind-boggling, really," Tilly said.

The research is a follow-up to results the team reported in March 2004, when it claimed it had shown that mice can produce eggs throughout their lives. For decades, scientific dogma has been that female mammals such as mice and humans are born with a finite number of eggs. To alleviate doubts about their original claim, the researchers conducted another round of experiments, which they said confirm the findings and explain how it might work.

First, the scientists sterilized female mice with a cancer chemotherapy drug that destroyed eggs in the ovaries but spared any egg-producing cells elsewhere. They tested the animals' ovaries 12 to 24 hours later and found signs their egg supply was rapidly regenerating. Two months later, the animals' ovaries looked normal, and they remained that way for life.

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