A stem cell breakthrough by American scientists is set to overturn ethical objections to potentially live-saving research.

They have found how to make stem cells from embryos without destroying the embryo in the process - an advance that could open the door to billions of dollars in research funding.

Stem-cell research, which specialists believe holds the key to treating many diseases, has been crippled in the US by the religious Right, backed by the Bush Administration. Federal support for such research has been banned because it involves the destruction of embryos.

Now a team at Advanced Cell Technology - a private company - has found that it is possible to create human stem cells using one or two cells from an early embryo, without doing any damage to the embryo.

In theory, the technique could be used to create both a baby and a set of immortal stem cells unique to that baby that might be used decades later to cure the baby - now adult - of diseases such as Parkinson’s or heart disease.

Much more likely, however, is that it will be used as a research technique to advance stem-cell science.

The technique is similar to pre-implantation genetic diagnosis (PGD) where one or two cells are detached from a blastocyst - a very early embryo, created in the case by in-vitro fertilisation - and tested to see if it carries a genetic mutation.

The method can prevent the passing on by parents of crippling genetic diseases.

The US team, led by Dr Robert Lanza, have now shown that a single cell harvested in this way can also be grown in culture to create stem-cell lines.

These are populations of cells that can be stored essentially for ever that have the potential to develop into any organ in the body.

“We have shown that we can not only generate stem cells without destroying the embryo, but that the remaining embryo also has the potential to go to on create a healthy blastocyst” said Dr Lanza, whose team’s research is published in Nature.

Asked if he expected the advance to satisfy President Bush, Dr Lanza said: “Well, as you know, the President objects to the fact that you would be sacrificing one life to save another, and in this instance there is no harm to the embryo.”

The team used embryos created for in vitro fertilisation, allowing them to multiply to eight or ten cells, or blastomeres, before removing one or two.

Most of these blastomeres, divided at least once more in the laboratory, and about half produced outgrowths of 50 to 100 cells including some identified as stem cells.

Two stable stem-cell lines were finally produced which continued to proliferate for more than eight months. Tests showed they had the ability to develop into the three cell categories from which all human tissue is derived.

The team concludes in Nature: “The ability to create new stem cell lines and therapies without destroying embryos would address the ethical concerns of many, and allow the generation of matched tissue for children and siblings born from transferred PGD embryos.”

British scientists, while admiring the technical skill of the experiments, doubted that they would revolutionise stem-cell research.

Professor Ian Wilmut, the scientist who cloned Dolly the sheep, said: “Cell lines have been obtained, but it is rather misleading to suggest that efficiency was equivalent to that with entire embryos.

“The authors imply that stem-cell line derivation was as efficient as it would have been if the entire embryo been cultured. It is not clear that was the case. The establishment of two lines from the equivalent of 35 high quality fresh embryos would be a disappointingly low efficiency.”

But John Harris, Professor of Bioethics at the University of Manchester, said: “The science is wonderfully interesting and important and will convince those who already accept PGD that the use of these cells is ethical.”

Professor Robin Lovell-Badge of the National Institute for Medical Research said the success rate was low, and that while it might be useful for couples undergoing PGD to have a stem cell line matched to a child for future therapeutic use, it is very unlikely to be taken up by anyone else.

“I am also unconvinced by the ethical arguments. Spare IVF embryos used to derive stem cell lines would have been destroyed anyway.”

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