Scientists for the first time have been successful in extracting stem cells from a cloned human embryo, the Guardian reports.
South Korean Dr Woo Suk-hwang of Seoul National University led the research, the results of which were published in the Science magazine.
"Our approach opens the door for the use of these specially developed cells in transplantation medicine," Woo told the magazine.
Scientists consider stem cells to be the basic blocks of a human body. They can, according to scientists, develop into any kind of cell or tissue provided the right conditions are created.
The success means that cloning is not longer in the realm of possibility, though many say it will be a long time before it is put in practice.
Dr Rudolf Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, told the Guardian that more research was required.
Critics, however, have slammed the research saying it involves destroying a human embryo, which is unethical. US President George Bush and his supporters in Congress want to ban it.
Last year in November the European Commission, backed by the European Parliament, voted to get stem cell research funded from the 17.5bn 2002-06 research budget.
European supporters of the research said the continent will fall behind in cutting-edge biotechnologies if it did not adopt clear rules. Others pointed to health benefits that would accrue out of the research.
Writing in the journal, Dr Woo and colleagues said they created the clone using eggs and cumulus cells donated by Korean women. Cumulus cells are found in the ovaries.
Scientists have cloned sheep, cattle, mice and other species but have had trouble cloning a human being. Last year a Massachusetts company, Advanced Cell Technology, said it had created a human cloned embryo but it had not grown to become a source of stem cells.
Stem cells are found throughout the body and are the primary building blocks of the body. But scientists typically face two problems. Adult stem cells are difficult to find and they are difficult to work with.
Many believe blastocysts -- stem cells taken from days-old embryos -- have much greater potential. Each one, when grown correctly, can be directed to become any kind of cell or tissue.
Woo used a technique called nuclear transfer, which involves removing the nucleus from an egg cell and replacing it with the nucleus of a so-called adult cell -- in this case a cumulus cell.
Each woman was cloned using her own egg cell and cumulus cell. The results were that the clones were exact copies of the women.
The egg cells were activated using a chemical process. One activated, the eggs started growing as if they had been fertilized by a sperm. Dr Woo and his team got 30 embryos to grow to the blastocyst stage, from which 100 stem cells were removed for research.
Experts praised the South Korean scientist's work. "It obviously represents a major medical milestone," Dr Robert Lanza, who has helped lead cloning experiments at Advanced Cell Technology, told the Guardian. "I think it could help spur a medical revolution."
Agencies
