Stem cell cure works on mice

Scientists have delivered the first therapeutic cloning gene therapy in work that further raises the prospect of the controversial technology sparking a revolution in medicine.

The experiment was carried out on mice by two teams at the Whitehead Institute for Biomedical Research in the United States.

It marks the first time that cell nuclear transfer has been successfully combined with gene therapy and directed embryonic stem cell (es-cell) differentiation. The result was a custom-made cure for a genetic disorder.

Rudolf Jaenisch and George Daley brought their teams together to conduct the proof-of-principle research.

They took skin cells from a mouse that was completely immune deficient due to a faulty gene.

The DNA-containing nucleus was stripped from each cell and inserted into an egg cell that had had its nucleus removed.

This hybrid cell was treated to "reprogramme" it so that it divided as though it was developing into an embryo. Es-cells were harvested from the resulting ball of cells.

The scientists corrected the genetic defect that caused the immune deficiency and added another gene that stimulated the generation of blood cells.

This latter step enabled them to avoid a biological problem that had held back similar therapeutic cloning experiments in the past.

The result was the creation of the precursors of blood-generating stem cells. These were then successfully transplanted back into the adult mouse.

The scientists found that this therapy rescued the mouse's immune system, although the "cure" was not complete. Dr Jaenisch, however, was satisfied. "These results show nuclear transplantation therapy can work in principle," he said.

The work, being published in the journal Cell , marks an important step towards unlocking the therapeutic potential in research recently given the support of the House of Lords.

The aim is to provide humankind with a way to fabricate organs and tissues from cells that are genetically matched to the patient to avoid rejection by the body after transplantation.