Journal issues correction to stem cell study

CHICAGO – In an effort to correct a misunderstanding about a study that described a way of creating embryonic stem cells while sparing human embryos, officials at the journal Nature said Thursday they plan to change the paper to make it clearer that all of the embryos used were destroyed.

The move comes after news outlets around the world reported last week that a research team at Massachusetts-based Advanced Cell Technology Inc. had succeeded in growing stem cells without destroying embryos in the process.

In reality, the Nature paper proposed that such a process could work, based on the research team’s unprecedented success in developing stem cells using single cells taken from early embryos. But none of the embryos from which the team harvested cells was left intact.

“The fate of the embryos isn’t obvious” in the paper, said a Nature spokeswoman.

Although the study’s main findings are unchallenged, she said the journal may modify the study abstract and a potentially misleading diagram.

In the study, the research group took four to seven cells from 16 human embryos, then tried to grow stem cells from each individual cell. The researchers say this was to maximize the number of cells they could test and improve the chances of obtaining stem cells.

Having proved the method, the scientists hope to show they can make stem cells from intact embryos that have had just one or two cells removed.

The clarification “doesn’t change the scientific point of the paper,” said study leader Robert Lanza of Advanced Cell Technology.

Yet in interviews last week, Lanza did not make it clear that none of the embryos in the study survived stem cell extraction.

In an audio interview for Nature last week, Lanza said, “in this instance there is no harm to the embryo that we’re biopsying.”

The study itself and comments by Advanced Cell Technology officials may have contributed to the misunderstanding. The paper does indicate the embryos were taken apart to extract single cells, or blastomeres, from which the team grew stem cells. But an accompanying figure titled “Derivation of (stem cells) from single blastomeres” shows a photo of a “blastomere-biopsied” embryo at a later stage of development. None of the embryos yielding stem cells survived to that stage.

A company news release last week also said the scientists had created stem cells “using an approach that does not harm embryos.” Ronald Green, a Dartmouth University ethics professor who advises the company, said he does not object to that description. “The approach does not harm embryos; the experiment did,” Green said.

This isn’t the first time Advanced Cell Technology has run into publicity problems.

In 2001 the company said it had cloned human embryos in the hope of developing useful stem cell lines. But other scientists said the effort was a failure because the cells divided only a few times before dying.

Company representatives said the Nature clarification plays into the hands of people who oppose stem cell research.

The fact that all the embryos were destroyed drew objection from Richard Doerflinger, an official with the U.S. Conference of Catholic Bishops.