Atala said the research reported in the scientific journal Nature Biotechnology expands far beyond similar work.
At a heart research conference in November, Swiss researcher Simon Hoerstrup said he managed to turn amniotic fluid stem cells into heart cells that could be grown into replacement valves. Hoerstrup has yet to publish his work in a scientific journal.
''Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well,'' Atala said.
It took Atala's team some 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.''
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,'' Atala said.
The hallmark of human embryonic stem cells, which are created 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 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 restricted federal funding for the embryo work since 2001, leading many scientists to search for alternative stem cell sources.
The advance is the latest in the so-called regenerative medicine field that has sprung from Atala's lab in Winston-Salem, N.C.
In April, Atala and his colleagues rebuilt bladders for seven young patients using live tissue grown in the lab.
In the latest work, 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, which means the cells came from the babies rather than the pregnant moms.
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