A bioethics twist: artificial stem cells

New procedure lets adult mouse cells mimic stem cells, bringing hope to anticloning activists.

from the June 7, 2007 edition

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Yet the limits also have prompted some labs to hunt for alternate ways to derive cells.

The adult-cell-to-stem-cell results built on a study published last year by a team from the University of Kyoto. It showed that by introducing into an adult cell four genes common to that mouse's cells and to embryonic mouse cells, that adult cell would be able to generate other major cell types. But the results were unclear about whether the newly altered cells fully mimicked embryonic stem cells.

They figured that somewhere in the large batch of altered cells, there might be some that mimic embryonic stem cells more fully. And they recognized that out of the four genes they initially introduced, two shut down once an embryo passed the stage where its stem cells begin to differentiate into the body's major cell types. So they devised a way to isolate cells with one of these genes, plus a second critical to stem cells. And they figured out how to identify and isolate the cells in which these two genes were active.

The Japanese group, and two US teams who used the same method for altering the adult cells, ran a series of tests to see how closely these artificial stem cells mimicked embryonic stem cells.

"It was surprising even to us" that the new cells acted like embryonic cells in virtually every way, says Marius Wernig, a researcher at the Whitehead Institute for Biomedical Research in Cambridge, Mass. The results appear in today's issue of Nature and the journal Cell Stem Cell.

Hopes and fears – from both sides

If the approach can be applied to humans, he adds, it could prove far more efficient at providing patient-specific cells for therapies than trying to derive the cells through cloning embryos reprogrammed with a patient's DNA. And it sidesteps the ethical quandaries that surround cloning and the use of human embryos.

He and others point out that while the results are encouraging, they shouldn't be used as a reason for clamping a lid on embryonic stem-cell research. Too little is known about the potential usefulness of adult-derived or embryonic stem cells to close the door to any option yet. Still, for people who view life as beginning at conception, this latest research represents "a very promising direction from the vantage point of ethics," says Father Tadeusz Pacholczyk, with the National Catholic Bioethics Center in Philadelphia.

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