It is a major advancement in the quest to grow patients' own replacement tissue to treat diseases.
The same scientists last year were the first to clone a human embryo. Now they have improved, by more than tenfold, their efficiency at culling these master cells, thus making pursuit of therapeutic cloning more practical.
"I didn't think they would be at this stage for decades, let alone within a year," said Dr. Gerald Schatten of the University of Pittsburgh. He acted as an adviser to the Korean lab in analyzing its data, which was being published Friday in the journal Science.
"This paper will be of major impact," said stem-cell researcher Dr. Rudolph Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Mass. "The argument that it will not work in humans will not be tenable after this."
This research is not cloning to make babies. Instead, scientists create test-tube embryos to supply stem cells, the building blocks which give rise to every tissue in the body and which are a genetic match for a particular patient, preventing rejection by the immune system.
If scientists could harness the regenerative power of those stem cells, they might be able to repair damage from spinal cord injuries, diabetes, Parkinson's and other diseases.