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Studies Outline Ways to Make Stem Cells Without Destroying Embryos

Posted on: Tuesday, 18 October 2005, 00:00 CDT

By Jeremy Manier, Chicago Tribune

Oct. 18--When researcher Rudolf Jaenisch started work earlier this year on a method of producing embryonic stem cells that would avoid ethical objections, one of his first hurdles was not scientific but personal: He did not believe there was any moral problem in the first place.

But practical considerations led Jaenisch and his team at the Massachusetts Institute of Technology to attempt the new stem cell extraction method, which they described in the journal Nature this week.

The need to destroy embryos to obtain stem cells has aroused powerful opposition to federal funding of such work. But Jaenisch thought if he could extract the cells without destroying a viable embryo, it might satisfy the opponents. And less controversy could mean more money for the field.

"I don't really have the objections that many people do have," Jaenisch said. "But you realize the realities in this country ... I think we need a compromise in this debate."

Jaenisch's report is one of two new studies in Nature that outline ways of making embryonic stem cells without destroying a viable embryo. Jaenisch harvested stem cells from a mouse embryo that was not viable: It was genetically altered so it could not develop in the womb. A separate group at Massachusetts-based Advanced Cell Technology was able to take cells from a normal mouse embryo without destroying it.

Some ethicists believe the work could help quell the uproar over federal funding of stem cell research, though others say the new methods are no better ethically than the techniques that caused the original objections.

That even the researchers involved are ambivalent illustrates the keen difficulty of finding common ground on the issue. William Hurlbut, a Stanford University bioethicist who first proposed the method that Jaenisch used, said the researchers are sincere in seeking a solution, though he acknowledged the irony of the situation.

"This is a strange moment in science, because scientists are trying to solve a problem that they don't feel is a problem," Hurlbut said.

In fact, Jaenisch voiced skepticism about the ethical merits of Hurlbut's idea during an interview with the Tribune in May. At that moment, Jaenisch now says, his own team already was trying to make the technique work.

The process involves altering a method of stem cell extraction called nuclear transfer, or therapeutic cloning.

In the original technique, researchers make an embryo by placing the nucleus of an adult cell in an egg cell that has been emptied of DNA. After an electric jolt, the egg begins dividing like an embryo, eventually forming a ball of cells that contains stem cells. Such cells can form any kind of tissue, offering the potential of new treatments for conditions such as Parkinson's disease and diabetes.

Hurlbut proposed altering this technique so that the ball of cells, called a blastocyst, cannot form a full-fledged person. Jaenisch's team did that in mice by silencing a gene called cdx2, which helps form the embryo's outer wall and, eventually, the placenta that keeps a fetus alive.

Such deficiencies, applied to human cells, would result in an entity with "a dramatically different developmental potential than a human embryo," Hurlbut said. Skeptics contend it would still be an embryo, albeit a damaged one.

In May, when the President's Council on Bioethics issued a report that contained some praise and criticism of Hurlbut's technique, Jaenisch agreed with many of the critics.

"Does being human or not depend on the state of one particular gene? That doesn't make sense," Jaenisch said.

Jaenisch still doesn't agree with the moral basis of the new technique, he said. But he said it was an interesting experiment that could provide a practical foundation for advancing the field.

The method doesn't solve any moral problem for Richard Doerflinger, deputy director of pro-life activities for the U.S. Conference of Catholic Bishops. In an e-mail response to questions, Doerflinger said taking out the cdx2 gene "seems to make a very damaged human embryo that cannot survive past a few days of development (instead of making a new entity that is not an embryo)."

Like Jaenisch, Robert Lanza, leader of the research team at Advanced Cell Technology, has long argued that embryonic stem cell research is morally acceptable as is.

Still, he said, "I regard the embryo with respect. If we can do this without offending anyone, fine."

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Source: Chicago Tribune

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