British medical researchers have grown human stem cells derived from spare IVF embryos for the first time.

The embryonic stem cell "line" will be the first to be added to a national tissue bank that could become the basis of a revolution in transplant surgery to treat a range of incurable conditions from heart disease to senile dementia.

Anti-abortion groups denounced the research on the ground that it involved the creation and destruction of human embryos - a procedure they claim is unethical.

The breakthrough means that scientists will be able to produce unlimited quantities of the cell line for studies into how stem cells develop into any of the dozens of specialised tissues of the body such as brain, muscle or liver cells.

Stephen Minger, who with his colleague, Susan Pickering, led the research team at King's College and Guy's Hospital in London, said the stem cell line was cultured from a spare human embryo that had been frozen for nearly five years.

This is the time limit imposed by the Human Fertilisation and Embryology Authority before frozen embryos must be left to die. Most of the embryos used in the study had been rejected for IVF treatment because of genetic defects.

Dr Minger said the scientists had extracted stem cells from just three of 58 embryos. Two of these died at an early stage. Only one set of stem cells survived to grow into a continuously replicating colony - a cell line.

"It's a first for Britain but it was by no means a trivial or easy procedure. We had to start from scratch and you learn things and teach yourself as you go along," Dr Minger said. "We are very excited about this development. Human embryonic stem cells are found in the earliest stages of development and are capable of giving rise to all the different types of cell in the body," he said.

"This means their possible therapeutic uses are almost endless and could help in the fight against diseases ranging from diabetes to Parkinson's," he added. The study is published in the journal Reproductive Biology Online.

Professor Peter Braude of King's College London said that the creation of a UK stem cell bank would mean that the maximum amount of research could be done using the minimum number of human embryos. "We are proud of the particular way that our lines have been generated. We believe that the derivation has been wholly ethical as the blastocysts [embryos] used would otherwise have been discarded," he said.

Worldwide, there are fewer than a dozen embryonic stem cell lines and only a few of these are freely available for research. Eventually, scientists hope to produce embryonic stem cell lines that meet the strict purity regulations necessary for human transplants so that they can implant them into patients' diseased organs.

Professor Richard Gardner of Oxford University, the chairman of a Royal Society working group on stem cells, said: "There is an urgent need for more properly validated lines that are made freely available to researchers if the therapeutic promise of embryonic stem cells is to be realised."

Professor Sir George Radda, the head of the Medical Research Council, said: "Stem cells offer new hope for treatments, and even cures, for many common diseases but a huge amount of research is needed to understand how they work and how their potential could be harnessed."

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