London: For the first time, scientists have created human embryos from slivers of skin, a feat they say has brought closer the day when babies are cloned in the lab.
In experiments that mirror the cloning technique used to make "Dolly the sheep", the researchers took cells from men`s arms and legs and placed them into women`s eggs.
The embryos created lived for only five or six days, but they represented a key step in the quest for treatments for incurable diseases from Alzheimer`s to cancer, they said.
Early-stage embryos have been made from human skin before, but the researchers claimed to have got further than anyone else.
Importantly, they appeared to have worked out where others have failed, meaning the research could now progress in leaps and bounds, a newspaper reported.
For their study, the scientists from the New York Stem Cell Foundation Laboratory paid 16 young women for their eggs and took tiny samples from the skin of two men.
They then placed the DNA from the skin cells inside the eggs and triggered them to grow and divide.
In the case of Dolly, the eggs used were "hollowed-out" -- their DNA had been removed. But here, the technique only worked properly when the eggs` DNA was left in, showing there is something about it that is vital for the creation of life.
The embryos, and the cells they contained, were mutants with three sets of DNA instead of the two. We normally have one from our mother and one from our father.
But the researchers, who detailed their findings in the journal Nature, are confident they will eventually be able to create healthy cloned embryos with the required two sets of genetic material.
The aim of the research is not to create cloned babies, but to extract stem cells -- "master cells" capable of becoming any type of body tissue -- from the embryos.
All stem cells gathered in this research were abnormal and not suitable for treating patients.
Worn out hearts could be patched up, aged brains could be rejuvenated and diabetics could be freed from the need to take insulin, all thanks to stem cells.
Susan Solomon, of the non-profit organisation behind the research, said: "Cell replacement therapy would dramatically change the treatment of and potentially even cure debilitating diseases and injuries that affect millions of people."
The extra genes in the embryos mean they do not, strictly speaking, qualify as clones.
But Josephine Quintavalle, of campaign group Comment on Reproductive Ethics, said: "Cloning is cloning however it is achieved. If women stopped selling their eggs, we could close down this unethical dead-end research once and for all."
In Britain, embryos can be cloned for research purposes but must be destroyed after 14 days and cannot be implanted into a woman.
Robert Lovell-Badge, a stem cell expert at the National Institute for Medical Research in London, meanwhile stressed that scientists are still a long way from being able to clone a baby.
"No respectable scientist or clinician has the intention of cloning people. In fact, there really isn`t any reason to do it," he said.