South Korean scientists have cloned the world's first mature embryonic stem-cell line, in what is seen as a breakthrough toward developing new methods of treating a wide range of degenerative ailments, a US science group reported.
But the controversial experiment announced on Wednesday is also likely to raise new concerns about cloning human beings.
"Because these cells carry the nuclear genome of the individual, after differentiation they could be expected to be transplanted without immune rejection for treatment of degenerative disorders," said Woo Suk-hwang of Seoul National University, the lead researcher on the project.
"Our approach opens the door for the use of these specially developed cells in transplantation medicine," he said in a statement released by the American Association for the Advancement of Science.
A summary of the study made public by the association said Woo and a group of other South Korean scientists were able to produce versatile and "pluripotent" stem cells by taking part of a non-reproductive cell from women and transplanting it into the women's eggs.
Blastocysts, or precursors to fetuses, produced through this transfer created a cell mass that was used to harvest well-developed embryonic stem cells, according to the document.
The method was used to develop a whole human embryonic stem-cell line, using a total of 242 eggs collected from 16 women, all unpaid volunteers.
These eggs made it possible to grow a total of 30 blastocysts and obtain 20 suitable inner-cell masses, the report said.
The resulting stem cells differentiated into all the main tissue types that appear in the early stages of human development, the researchers said.
When transplanted into mice, the stem cells differentiated into still more specific cell types, offering further proof of pluripotency, they noted.
The key to their success, the researchers believe, lay in using extremely fresh donor eggs, following stringent timing protocols and a special method of extracting DNA from eggs.
The approach has been previously used to generate cells from mice, but up to now, nobody had been successful in applying it to humans, US scientists said.
Experts said the South Korean experiment may represent a major step toward developing new cures for severe and chronic ailments such as diabetes, osteoarthritis, Parkinson's disease and others.
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