Stem cell experiment killed embryos, researchers say

Journal clarifies article on results of creating new lines for scientists

September 01, 2006|By Dennis O'Brien and Jonathan Bor | Dennis O'Brien and Jonathan Bor,Sun reporters

A study aimed at creating human stem cells without harming embryos has become the focus of a scientific debate and prompted two clarifications by the scientific journal that published it - with critics saying that researchers overstated the implications of their work.

The study by Advanced Cell Technology Inc., a California biotech firm, used 16 embryos donated by couples at fertility clinics to grow two stem cell lines.

In findings published last week in the journal Nature, researchers reported devising a way to create stem cell lines that does not necessarily require destroying embryos.

The researchers used a technique similar to one practiced at in-vitro fertilization labs: withdrawing single cells for genetic analysis but leaving the embryo capable of growing into a baby when implanted in a womb.

Many news outlets, including The Sun, reported that the embryos had survived the experiments.

But for practical reasons, the scientists withdrew numerous cells from each embryo, destroying them in the process.

Embryonic stem cells are the building blocks of the body, theoretically able to turn into any kind of tissue. Researchers believe they're key to therapy for a host of deadly or crippling diseases.

But critics oppose embryonic stem cell research because the embryos - generally discards from in-vitro fertilization centers - are destroyed in the process of extracting the cells.

With the Bush administration refusing to fund research into new stem cell lines, the report of a process that extracted them without destroying the embryo excited the scientific community.

Nature editors have acknowledged that they erred in a news release describing the study as "plucking single cells from human embryos" in a way that generated new stem cell lines "while leaving the embryo intact."

A subsequent clarification noted that the researchers removed "multiple cells" from some embryos. A second clarification acknowledged that the embryos were destroyed in the experiments. The fate of the embryos was not discussed in the paper.

Critics say the researchers' claims went too far.

"They certainly didn't get a stem cell line without destroying any embryos," said Richard Doerflinger, deputy director of pro-life activities for the U.S. Catholic Conference of Bishops.

M. William Lensch, a stem cell researcher at Harvard, said using the method to create stem cell lines might be more difficult than the study implies because it's not clear why only a small percentage of the extracted cells formed new lines.

"I think the study was written in a clever way so that it's technically correct, but what they claimed beyond the paper, and on the Nature Web site and in the popular press, isn't right," he said.

In an interview yesterday, Dr. Robert Lanza, the senior author, noted that he and his team never claimed the embryos survived the experiments. When the study was published, Lanza and other experts had noted in interviews that embryos routinely survive when single cells are extracted in genetic tests at fertility clinics.

He said it was clear in the Nature report that the eight- to 10-cell embryos were destroyed because it noted that a total of 91 cells were extracted from the crop of embryos used.

Lanza said the criticism is motivated by the controversial nature of embryonic stem cell research.

"This is what happens when you try to break up a fight - you get beaten up by all sides," he said.

The embryos were destroyed because researchers needed a significant number of cells, or blastomeres, for the study, he said.

"We did it that way to maximize the number of blastomeres and to minimize the number of embryos we needed," he said. "The study conclusions and the implications remain 100 percent accurate."

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