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Scientists Find New Stem Cell Source in Amniotic Fluid

U.S. researchers have discovered a new source of stem cells that appear to hold almost as much promise for regenerating human tissue as the controversial embryonic stem cells. The scientists have identified them in the amniotic fluid that protects an unborn child. VOA's David McAlary reports.

It took researchers from Wake Forest and Harvard Universities seven years of complicated laboratory testing to show that the amniotic cells they had found were truly stem cells. This is because the fluid is filled with many other kinds of cells the embryo casts off as it develops.

Stem cells are unprogrammed cells that can develop into tissue. They are a reserve the body calls upon to replace cells in organs. Some stem cells are limited to becoming certain types of tissue, such as so-called adult stem cells found in any person at any age. But the type of stem cell in the unborn can turn into any tissue in the body and are highly prized for research into therapies for diseases.

Yet, these fetal stem cells are controversial because they are taken from discarded embryos. Opponents of fetal stem cell research argue that it encourages the destruction of embryos. In the United States, President Bush has restricted government funding for fetal stem-cell studies.

The Wake Forest and Harvard University investigators say the amniotic stem cells might be almost as versatile as the embryonic type and can be extracted without harm to the fetus or the mother at any time during gestation or from the placenta after birth.

"That is important because then you have a very nimble cell that you can drive to become anything you want it to become, hopefully," said Anthony Atala.

Anthony Atala is a Wake Forest scientist. In a paper in the journal Nature Biotechnology, he and his colleagues report that in laboratory dishes, they were able to coax amniotic stem cells into differentiating into cells for fat, bone, muscle, blood vessels, nerves, and the liver.

In mice, they used the nerve cells to replace damaged brain tissue and bone cells to fuse into healthy bone.

"We believe that this will be just one more source of stem cells for research and hopefully someday for clinical application," he said.

The reaction to the finding is positive from opponents of embryo destruction for research. A spokesman for the U.S. Conference of Catholic Bishops, Richard Doerflinger, calls the discovery very good news.

"It means that embryos that some researchers have been looking at as just research material might actually provide beneficial stem cells if you let them live and be born," said Richard Doerflinger.

Stem cell researchers generally are cautiously hopeful about the medical potential of the amniotic stem cells. News reports quote several as saying the cells might not be quite as versatile, or, as scientists say, "pluripotent" as the embryonic type, but are nevertheless a major step forward in the field.

Others say studies into embryonic stem cells should continue.

Anthony Atala says only further research will tell what the potential is for the amniotic variety.

"The cells are pluripotent, just like human embryonic stem cells, but we do not know what the extent of therapy will be yet with these cells," he explained. "Of course, we do not know that yet human embryonic stem cells either, but time will tell for all these cells types."

Atala warns that his work is in its early stages and still several years away from use in a patient.