The stem cell wars are over. Leading scientists are telling us that they can pursue the most promising stem cell research without using--much less killing--human embryos. This breakthrough enables researchers to create human embryonic stem cells directly from adult cells. In fact, the new method may actually prove superior to embryo-destructive alternatives. This is the biggest stem cell advance since James Thomson became the first scientist to isolate embryonic stem cells, less than a decade ago.

It is a new study by Thomson himself that has caused the present stir, but this time Thomson is not alone. Accounts of independent research by two separate teams of scientists were published on November 20--one in the journal Cell and one in the journal Science--documenting the production of pluri-potent human stem cells without using embryos or eggs or cloning or any morally questionable method at all.

The new technique is so promising that on November 16, Ian Wilmut announced that he would no longer seek to clone humans. Wilmut, you may remember, is the scientist who cloned Dolly the sheep. He recently sought and received a license from the British government to attempt to clone human embryos for research purposes. Now, citing the new technique, he has abandoned his plans.

It was only in 1998 that Thomson succeeded in isolating human embryonic stem cells. Though other types of human stem cells were known at the time (some were even in clinical trials), embryonic stem cells were thought to be the holy grail because they were believed to be more flexible. They were "pluripotent"--capable, in theory, of developing into any type of body tissue--whereas so-called adult stem cells were thought to be useful for forming a narrower range of tissue types. The problem with producing embryonic stem cells was that human embryos--nascent human beings--had to be destroyed in the process.

Even now, nine years later, embryonic stem cells are thought by many scientists to have greater potential than other types. This reputation persists even though adult stem cells are already used in therapies to treat several diseases and are being tested in hundreds of clinical trials, while not a single embryonic stem cell therapy exists, even in trials.

As anyone familiar with reparative medicine knows, immune rejection is one of the tallest hurdles to clear. The promise of cloning was that therapies could be produced using human embryos cloned directly from the patient--thus resulting in a genetic match. Cloning, it was said, would also provide an unlimited supply of human embryos. But many people thought human cloning with the sole intention to kill crossed an ethical line. In addition, human cloning would require an enormous number of human eggs--which could be obtained only by subjecting donors to painful and potentially dangerous hormonal-stimulation procedures. The fear was that likely "donors" would be poor women undergoing a distasteful procedure solely for the fee.

On August 9, 2001, President Bush waded into this morass. He issued an executive order that opened human embryonic stem cell research to federal funding for the first time ever. The order also restricted that funding, however, to research using existing embryonic stem cell lines: No more embryos would be created and destroyed for taxpayer-funded research. (Contrary to popular belief, Bush's order did not ban anything.) Opposition was fierce, but Bush stood firm.