US: A US-based company has produced potentially valuable embryonic stem cells without having to destroy the human embryo that supplied them.
The originators of the technique say their method eliminates any ethical doubts about the use of embryonic stem cells to fight disease, but ethicists argue that serious ethical issues remain.
Details of the experiments on 16 surplus human embryos by Advanced Cell Technology of Worcester, Massachusetts were detailed yesterday in the journal Nature. The embryos were left over after in-vitro fertilisation treatments.
The researchers claimed to have plucked just a single cell from very early eight-cell embryos and managed to create two stem cell lines that have survived for at least eight months. The embryos remained viable despite the loss of a cell, the company said.
Stem cells are highly prized because they can transform into any of the body's dozens of cell types. Medical researchers believe stem cells will provide a way to cure a variety of diseases, from Parkinson's and Alzheimer's to the muscle damage caused by heart attack.
There are huge ethical and political difficulties related to the use of embryonic cells however, given all previous techniques for harvesting stem cells involved the destruction of the embryo.
The company believes these ethical concerns can now be overcome. "I hope this will solve the political impasse and allow scientists to move on," said Dr Robert Lanza who led the research.
The team based their work on a technique already being used as a way to diagnose genetic diseases when using in-vitro fertilisation. Preimplantation genetic diagnosis (PGD) involves taking a single cell from a dividing eight-cell embryo and testing it for disease while allowing the remaining cells to grow before being placed for implantation in the womb.
The researchers decided to culture the single cell to produce more, and managed to create two separate cell lines from the original 16 embryos.
They believe the embryos showed clear signs of remaining viable, while the resultant stem cells were apparently fully capable of transforming into different cell types.
"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," the authors suggest.
Ethical problems remain however according to the science director of the Irish Council for Bioethics, Dr Siobhán O'Sullivan.
"The ethical difficulties with that are the eight-cell embryo could have become twins or triplets. Also you have no idea what difficulty you have made by taking away that one cell from the embryo. This is not going to sort out the ethical difficulties," Dr O'Sullivan said.
Similar doubts were expressed by the professor of obstetrics and gynaecology at King's College London, Prof Peter Braude. PGD was not used "willy-nilly as it is better not to remove a cell from a developing embryo unless one really has to", he said.
"While perhaps a clever trick, I do not feel that this is much of an advance," stated Prof Robin Lovell-Badge, head of developmental genetics at the UK Medical Research Council National Institute for Medical Research.
"The success rates were low as only 2 per cent of cells isolated from the embryos gave rise to embryonic stem cell lines. In other words, at this rate it would only work for one in 50 embryos." - (Additional reporting, PA)