Stem cells found plentiful in amniotic fluid

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Scientists reported yesterday that they had found a plentiful source of stem cells in the fluid that cushions babies in the womb and produced a variety of tissue types from these cells, sidestepping the public fight over destroying embryos for research.

Researchers at Wake Forest University and Harvard University reported that the stem cells they drew from amniotic fluid donated by pregnant women hold much the same promise as embryonic stem cells.

They reported that they were able to extract the stem cells without harm to mother or unborn baby and turn their discovery into several tissue cell types, including brain, liver and bone.

"Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well," said Dr. Anthony Atala, head of Wake Forest's regenerative medicine institute and senior researcher on the project.

It took Dr. Atala's team about seven years of research to determine the cells they found were truly stem cells that "can be used to produce a broad range of cells that may be valuable for therapy."

The scientists noted that they still don't know exactly how many cell types can be made from the stem cells found in amniotic fluid and that preliminary tests in patients are years away.

Still, Dr. Atala said, the research reported in the scientific journal Nature Biotechnology expands far beyond similar work discussed at a heart research conference in November. There, Dr. Simon Hoerstrup said he managed to turn amniotic fluid stem cells into heart cells that could be grown into replacement valves. But the Swiss researcher has yet to publish his work in a scientific journal.

Dr. Atala said the new research has found even more promising stem cells with the potential to turn into many more medically useful replacement parts.

"We have other cell lines cooking," Dr. Atala said.

The hallmark of human stem cells, which are created in embryos in the first days after conception, is the ability to turn into any of the more than 220 cell types that make up the human body. Researchers are hopeful that they can train these primordial cells to repair damaged organs in need of healthy cells.

However, many people, including President Bush, oppose the destruction of embryos for any reason. The Bush administration has severely restricted federal funding for the embryo work since 2001, leading many scientists to search for alternative stem-cell sources.

It's the latest advance in the field of regenerative medicine that has sprung from Dr. Atala's lab in Winston-Salem, N.C. In April, he and his colleagues rebuilt bladders for seven young patients using live tissue grown in the lab.

In the latest work, Dr. Atala's team extracted a small number of stem cells swimming among the many other cell types in the amniotic fluid. One of the more promising aspects of the research is that some of the DNA of the amnio stem cells contained Y chromosomes, meaning the cells came from the babies rather than the pregnant mothers.

Dr. George Daley, a Harvard University stem-cell researcher, said that finding raises the prospect that someday expectant parents can freeze amnio stem cells for future tissue replacement in a sick child without fear of immune rejection.