• Big step towards growing patients’ own replacement tissue to treat diseases
• ‘Therapeutic technique’ is not cloning to make babies
SCIENTISTS have successfully extracted stem cells from a cloned human embryo for the first time, it was announced today.
Experts in Britain hailed the work as a "major step forward" in a science that could one day offer treatments for diseases such as Parkinson’s and diabetes.
The technique is not cloning to make human babies but to create cells that could grow into any tissue, and could potentially be used to replace damaged tissue.
The breakthrough by researchers in South Korea marks an important step forward.
The experiment, reported in tomorrow’s edition of the US magazine Science, is certain to revive the international controversy over human cloning.
Crucially, the tissues that are grown in this way appear as though they will not be rejected by the immune system of the patient they were cloned from.
The technique offers the potential of breakthrough treatments for many common diseases, but any therapy is years away from being tested in people.
Scientists have used therapeutic cloning to partially cure laboratory mice with an immune system disease. And they know how to cull stem cells from human embryos left over in fertility clinics, offering the potential of cell therapy but not patient-specific treatment.
But attempts at cloning a human embryo in the stem cell quest have failed until now.
Scientific commentators have described the breakthrough as the most significant advance in cloning technology since Dolly the sheep. Dolly, the world’s first cloned mammal, was created by Professor Ian Wilmut and his team at the Roslin Institute in Midlothian.
Scientists from Seoul National University report they succeeded in the new breakthrough and their findings have been accepted by international experts.
The Korean researchers say the breakthrough is largely down to using extremely fresh eggs donated by South Korean volunteers and finding a gentler way of handling the genetic material inside them.
It is elegant work that provides long-anticipated proof that the technique is possible using human cells, said stem cell researcher Dr Rudolf Jaenisch of the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts. "That’s an important point to prove," he said.
"Still, it’s not of practical use at this point," he added, stressing that years of additional research are required.
For one thing, the cloning technique still does not work well: The Seoul team collected 242 eggs, from which they succeeded in cloning 30 blastocysts - early-stage embryos containing a mere 100 cells. From those, they harvested just one colony of stem cells.
Still, it is likely to renew debate over whether all forms of human cloning should be banned. The US House of Representatives last year voted to do that, but the Senate stalled over whether there should be an exception for research of this type. Internationally, the United States is pushing for a UN ban of all human cloning, too. The UN General Assembly recently postponed a decision. There is almost universal support for a global ban of reproductive cloning, but Britain and a number of other countries want cloning for medical experiments left unhindered.
Editor-in-chief of the journal Science, Donald Kennedy, said: "These results seem promising. But, it’s important to remember that cell and tissue transplantation and gene therapy are still emerging technologies, and it may be years yet before embryonic stem cells can be used in transplantation medicine."
Addressing ethical concerns, he also called for a worldwide ban on activities which would seek to use this technology to create living children.
Professor Hwang, whose expertise has been developed in animal cloning, said any attempt to produce a baby would be "crazy". "We will never try to produce cloned human beings," he said. "During animal cloning, we experienced so many difficulties and dangers with deformities, especially in the internal organs."
Roger Pedersen, professor of regenerative medicine, at Cambridge University, hailed the Korean work as a major advance.
He said: "The present work has substantially advanced the cause of generating transplantable tissues that exactly match the patient’s own immune system.
"These researchers’ findings also make it possible to learn how to reprogramme the human genome to an embryonic state.
"This will likely accelerate the development of alternative ways of reprogramming human cells, which could in the future diminish the need to use human eggs for this purpose."