Human embryonic stem cells have been created without destroying embryos, in an advance that sidesteps ethical objections to the research and could unlock billions of dollars of funding.

The success could also herald a new approach to personalised medicine, allowing parents to conceive children who have a unique “spare-part kit” of master cells that match their genetic profiles precisely.

Embryonic stem (ES) cells have vast medical promise because they can form any tissue in the body and could be grown into replacements for cells damaged in conditions such as diabetes, Parkinson’s and spinal paralysis.

However, research has been held back by opposition from some religious groups who regard it as unethical because harvesting the cells has, so far, involved the destruction of embryos. In 2001 the Bush Administration banned US scientists from using federal grants to study all but a handful of ES cell colonies or lines, cutting off the main source of funding.

A technique pioneered by Robert Lanza, of Advanced Cell Technology, a company based in Massachusetts, could provide a fresh source of stem cells that are ethically acceptable to the US Government.

His team has produced five ES cell lines by plucking one or two cells from early embryos, then culturing them in the laboratory. Dr Lanza first demonstrated that ES cells could be made in this way in 2006, but the eight-cell embryos he used were destroyed in the experiments. He has now repeated the method without killing the parent embryos, which were frozen. In theory, these could be thawed and implanted into a womb.

The cell extraction procedure is known to be safe because it has been used for almost two decades to screen embryos for genetic diseases. Dr Lanza has also improved the efficiency of the technique. While only 2 per cent of extracted cells developed into ES cell lines in his 2006 experiments, he has succeeded with 20 to 50 per cent of cells this time. This means that it may be possible for couples to conceive IVF embyros from which a cell would be removed before transfer to the womb. This would create ES cells that would be genetically identical to the baby and could be used for replacement tissue later in life.

The more immediate application of the work, which is published in the journalCell Stem Cell, should be to expand the number of ES cell lines available to federally funded scientists in the US. Dr Lanza said that his team has already approached the White House about approving the technique, but that officials had said that they would consider it only once the work had been published.

Dr Lanza said that immediate approval of the technique would mean more experiments could be started right away. “If the White House approves this new methodology, researchers could effectively double or triple the number of stem cell lines available within a few months. Too many needless deaths continue to occur while this research is being held up. I hope the President will act now and approve these stem cell lines quickly,” he said.

Research using ES cells is permitted in Britain under licence from the Human Fertilisation and Embryology Authority, so there is likely to be less demand for lines created with the new technique.

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