Stem cell work spurs hope

New stem cell research in mice raises the possibility that women may someday be able to harness their own eggs to help fight disease in themselves or their relatives, Harvard University researchers reported yesterday.

The scientists generated embryonic stem cells from an unfertilized mouse's egg -- a feat that has been performed before. They then managed to select stem cells that were genetic matches for the mother's immune system, so that the cells could grow into new tissue in her body without being rejected as invaders.

The method used chemical treatments to prompt the egg to develop into an embryo, a process known as parthenogenesis, and then extracted stem cells from it.

The embryo could not have otherwise developed into a baby mouse, so, even in humans, the strategy is unlikely to raise as serious ethical objections as other methods that destroy a viable human embryo.

The immediate benefit of the technique is for researchers; it still has many hurdles to overcome before it will be clear whether it is safe for use in humans, said George Q. Daley of Children's Hospital Boston, senior author of the paper published online in the journal Science. There is concern, for example, that such cells could become cancerous.

But, he said, the technique may be closer to working in humans than somatic cell nuclear transfer, the conventional approach in animals for generating customized embryonic stem cells.

In that method, a nucleus from a regular cell such as a skin cell is inserted into an egg and induced to develop.

Also known as therapeutic cloning, it is highly inefficient in animals and has yet to be mastered in humans, though two Harvard teams, including Daley's, are trying.

"This is a much more workable approach to generating patient-specific and tissue-matched embryonic stem cells," Daley said. "But the trade-off is that these cells may not prove to be normal and functional."

If the egg technique works in humans, women would be their own immediate beneficiaries, but the effects could be wider, Daley said. It could also lead to the broader production of stem cells that have only half the usual set of immune system genes -- perhaps even whole banks of such cells -- and that therefore would be compatible with many patients who need to grow new tissue.

Carey Goldberg can be reached at goldberg@globe.com.