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November 22, 2006
Journal Clarifies Stem-Cell Report
By NICHOLAS WADE
The scientific journal Nature today issued a clarification of a recent report that human embryonic stem cells could be derived without harm to the embryo, but the journal affirmed the report’s scientific validity.

The finding, by Robert Lanza and colleagues at Advanced Cell Technology in Worcester, Mass., caused a stir when it was published online in August, because it seemed to undercut the argument of stem-cell opponents that working with the cells necessarily means a potential human life has to be destroyed.

Dr. Lanza’s approach is made possible by pre-implantation genetic diagnosis, a test used in fertility clinics. In the test, one cell is removed for genetic testing when the embryo has reached the eight-celled stage, apparently doing the embryos no harm. Embryos tested in this way have been implanted and have resulted in the births of apparently healthy children.

Dr. Lanza showed that the one removed cell can be used to generate the embryonic stem cells used in research. The usual method for obtaining them involves a somewhat more advanced embryo, which is destroyed in the process.

Dr. Lanza’s article appears in the printed issue of the journal dated Thursday, along with itemized changes that have been made in the text, as well as an addendum by Dr. Lanza and his colleagues.

The changes spell out issues that were misunderstood or misstated at the time, including in an early Nature press release. Among them was that although Dr. Lanza said others could use his method to avoid destroying embryos, he himself had destroyed those used in his experiments, by using many cells from each rather than just one. Had he taken a single cell from each eight-celled embryo, a much larger number would have been needed — and eventually destroyed.

Dr. Ritu Dhand, Nature’s chief biology editor, said the sole purpose of the clarification was to make the article easier to understand. “There was nothing either scientifically or technically wrong with the paper,” she said. Dr. Dhand added that the journal had the article reviewed by experts a second time, “just to be sure that everything was as it should be.”

It is too soon for other laboratories to have repeated Dr. Lanza’s work, the acid test for new scientific findings. Dr. Lanza said that he had just finished training a team from the University of California, San Francisco, in how to use his technique, and that he expected visitors from four other laboratories.

Dr. Richard Doerflinger, a spokesman for the U.S. Conference of Catholic Bishops, said it was still unproved that stem cells could be derived from a single blastomere, or cell from the very early stages of embryo development, without harming the embryo. The bishops’ conference opposes embryonic stem-cell research.

http://www.nytimes.com/2006/11/22/science/23stemcnd.html?ei=5094&en=13d6158df8d9e8b1&hp=&...