Scientists have used cloning technology to transform human skin cells into embryonic stem cells, an experiment that may revive the controversy over human cloning.
The researchers stopped well short of creating a human clone. But they showed, for the first time, that it is possible to create cloned embryonic stem cells that are genetically identical to the person from whom they are derived.
These stem cells could go on to differentiate into heart, nerve, muscle, bone and all the other tissue types that make up a human body.
Since the birth of Dolly the sheep in 1996, researchers have cloned about 20 species, including rabbits, goats, cows and cats. Yet they have been unable to create biologically identical copies of any monkey or primate, including humans, possibly because their reproductive biology is more complicated.
But the refinements described Wednesday in the latest experiment suggest that "it's a matter of time before they produce a cloned monkey," said Jose Cibelli, a cloning expert at Michigan State University, who wasn't involved in the study. It also means, he added, "that they are one step closer to where the efficiency is high enough that someone is willing to try" to clone a person, though that remains a distant—and to some, disturbing—prospect.
The experiment was published online in the journal Cell. It was funded by Oregon Health and Science University and a grant from Leducq Foundation of France.
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