Advances don't quell stem-cell debate

If headlines turn out to be prophetic, Nov. 20, 2007, was a historic day in the decade-long ethical debate over embryonic stem-cell research. "Scientists Bypass Need for Embryo to Get Stem Cells," reads The New York Times. "Major leap for stem cells," the Chicago Tribune added. "Advance May End Stem Cell Debate," chimed The Washington Post.

But headline prophecies are a tricky business and less than two months later, it appears The Washington Post was wise to use the word, "may."

On Nov. 20, the Tuesday before Thanksgiving, Shinya Yamanaka of the University of Kyoto, Japan, and James A. Thomson of the University of Wisconsin both published papers from separate experiments with similar results: by inserting four key genes, they were able to reprogram adult human skin cells into acting like embryonic stem cells. Those reprogrammed stem cells could someday be grown into any kind of human tissue and offer potential cures to major diseases. All this without extracting the cells from human embryos, a method that draws fire from pro-life activists who believe life begins when an egg is fertilized.

But the debate is not over yet.

The news certainly had the chairman of the Committee for Pro-Life Activities at the U.S. Conference of Catholic Bishops ready to sing certain scientists' praises.

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"Studies published this week in the journals Cell and Science offer new hope for advancing stem-cell research and therapies while fully respecting the dignity of human life," wrote Cardinal Justin Rigali of Philadelphia.

Such conclusions go too far, according to William B. Neaves, president and CEO of the Stowers Institute for Medical Research in Kansas City, Mo. "These are important advances toward the ultimate goal of being able to directly reprogram human cells," said Neaves. "But by no means do these advances mean that one should cut back in any way on the effort devoted to research with human embryonic stem cells."

Few question the potential good that stem-cell technologies represent. By being able to create new tissue, stem-cell therapy could someday cure a vast number of diseases and disabilities, including Parkinson's disease, diabetes and spinal cord injuries. One of the most exciting elements of reprogrammed cells is that the patients would be their own donors.

A new dilemma?

Statements like the one made by Rigali had Neaves wondering if pro-life activists fully understood the implications of Yamanaka's and Thomson's conclusions.

"The issue that has been overlooked is that when one directly reprograms an ordinary body cell ... one has transformed that ordinary skin cell into the functional equivalent of a fertilized egg," said Neaves, whose center was the prime target in a 2004 Catholic church-led attack on stem-cell research in Missouri. In 2006, Missouri voters narrowly approved an amendment to the state constitution that protects embryonic stem-cell research in the state.

Neaves pointed to the June 6 paper in the journal Nature by Rudolph Jaenisch, a professor of biology at Massachusetts Institute of Technology. In that paper, Jaenisch reports that he was able to verify Yamanaka's earlier research, which reprogrammed mice skin cells into stem cells that were pluripotent, meaning they can form many different kinds of tissue, just like embryonic stem cells. It was how Jaenisch came to this conclusion, Neaves said, that should worry opponents to embryonic stem cell research.

The team Jaenisch supervised at the Whitehead Institute for Biomedical Research, in Cambridge, Mass., created a genetically abnormal mouse embryo that consisted of only placenta rather than the entire fetus. The reprogrammed stem cells, called induced pluripotent stems (iPS), were injected into the embryo and then placed into a uterus. The combination of the placenta and the stem cells resulted in a late-term mouse fetus.

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"This is the most stringent criteria anyone can use to determine if a cell is pluripotent," said Jaenisch in a paper released by the Whitehead Institute.

And also presents new ethical problems for hardliners who oppose embryonic stem-cell research, Neaves pointed out.

"This argument that [Neaves] is making is a flawed argument," said Fr. Tadeusz Pacholczyk, neuroscientist and director of education for the National Catholic Bioethics Center. "If you're talking about that process itself, then you are talking about an alternative technique for deriving embryonic-type stem cells without involving any embryos at all. At this point there is no question that you have not utilized any kind of embryo anywhere in the entire process."

But Yamanaka himself shares some concerns about ethical slippery slopes, according to an interview he gave the British publication New Scientist Dec. 14.

"I can make eggs as well as sperm from my own male iPS cells," Yamanaka said. "What if somebody took those sperm and eggs from a single person and fertilized them? The result would not be a clone because of the way cells divide during sexual reproduction ... but it would be something very strange and dangerous."