After more than 15 years of failures by scientists around the world and one outright fraud, biologists have finally created human stem cells by the same technique that produced Dolly the cloned sheep in 1996: They transplanted genetic material from an adult cell into an egg whose own DNA had been removed.
The result is a harvest of human embryonic stem cells, the seemingly magic cells capable of morphing into any of the 200-plus kinds that make up a person.
The feat, reported on Wednesday in the journal Cell, could re-ignite the field of stem-cell medicine, which has been met with technical challenges as well as ethical issues.
Until now, the most natural sources of human stem cells have been human embryos, whose use in research poses ethical quandaries. The technique announced on Wednesday, by scientists at Oregon Health & Science University and the Oregon National Primate Research Center, uses unfertilized human eggs.
Eliminating the need for human embryos could boost attempts to use stem cells and their progeny to replace cells damaged or destroyed in heart disease, Parkinson's disease, multiple sclerosis, spinal cord injuries, and other conditions.
But the achievement could also revive fears of reproductive cloning, or producing genetic copies of living (or dead) individuals.
Even before the study was published, a British watchdog group Human Genetics Alert protested the research.
"Scientists have finally delivered the baby that would-be human cloners have been waiting for: a method for reliably creating cloned human embryos," said Dr. David King, the group's director. "This makes it imperative that we create an international legal ban on human cloning before any more research like this takes place. It is irresponsible in the extreme to have published this research."
Among scientists, however, the accomplishment is being hailed as "a tour de force," as stem cell biologist George Daley of the Harvard Stem Cell Institute put it. "This represents an unparalleled achievement. They succeeded where many other groups failed, including mine."
The highest-profile failure was that of biologist Hwang Woo-suk of Seoul National University in South Korea. In 2005 he and his team made headlines across the globe when they claimed, in the journal Science, that they had created human embryonic stem cells via nuclear transfer, the same technique the Oregon scientists used. Hwang's claim turned out to be a lie, making it one of the most infamous cases of scientific fraud in the last decade.