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Scientists have cloned embryos for the first time from patients with serious diseases and injuries. The research at Seoul National University in South Korea demonstrates the principle of “therapeutic cloning” producing stem cells genetically identical to the patient, which could repair damaged or diseased tissue.
Hwang Woo-suk, the study leader, called it “a giant step forward towards the day when some of mankind's most devastating diseases and injuries can be effectively treated through the use of therapeutic stem cells”.
The results, published online on Thursday by the journal Science, illustrate the way Asian countries - China and Singapore as well as South Korea - have established a world lead in some areas of human stem cell science. In an interview, Prof Hwang said this is partly because of supportive political and social attitudes in Asia in contrast to the US and many European countries, where embryo research and therapeutic cloning are either banned or mired in controversy.
The Korean team has made rapid technical progress since producing the world's first cloned human embryos early last year. Those embryos were clones of the same healthy young women who had donated 242 eggs to the study and the scientists cultured stem cells from only one embryo.
In the new project they took eggs and DNA from different people. The resulting clones were from patients of both sexes, aged from 2 to 56, who were suffering from spinal injury, juvenile diabetes or a congenital immune disease. Starting with 185 donated eggs, they produced 31 embryos, 11 of which yielded stem cells.
Independent scientists, who had expressed doubt about Prof Hwang's original study, acclaimed the latest results. “Some thought that his earlier success with cloning only worked because it used a woman's egg and the [ovarian] cells surrounding it,” said Anne McLaren of Cambridge University. “But now: good news for men. Some of the cloned lines were derived from men's skin cells.”
All therapeutic cloning research uses “somatic cell nuclear transfer”, the technique developed at the Roslin Institute in Scotland to produce Dolly the sheep. The Korean scientists transferred the nucleus from a patient's skin cell into a human egg whose own nucleus had been removed. The egg was then stimulated to develop into an early embryo. Cells were removed when the embryo was a microscopic ball six days old, and cultured with nutrients and growth factors to become a self-replicating “line” of stem cells.
Prof Hwang said a key factor in his team's success was the availability of eggs from fertile donors, instead of ones left over from fertility treatment which some western research groups have tried to use.
Speaking in London about his research, Prof Hwang warned people not to expect clinical applications in the near future.