Scientists in Canada have turned adult skin cells into the building blocks of brain cells — opening the way for their use in new therapies for such incurable diseases.

The discovery, by a team at the University of Toronto, is particularly exciting as it promises to provide a readily accessible and ethically neutral source of neural stem cells — the precursors of nerve and brain tissue.

While other groups have managed to create these cells before, they have generally required the use of adult stem cells from bone marrow, which are difficult and painful to extract, or embryonic stem cells, which require the destruction of a human embryo.

If the Toronto technique is perfected for clinical use it would allow neural stem cells to be made from a patient’s skin, ensuring a perfect genetic match that would not be rejected by the body. The cells would then be transplanted into the brains of people with neurological disorders, to replace, for example, the specialised dopamine neurons that are lost in Parkinson’s disease.

They also have potential for testing new drugs and for long-term research into conditions such as autism, which are believed to be caused by nerve cell abnormalities.

In the study, scientists removed samples of skin from patients undergoing biopsies. They then used a growth factor to culture the cells, creating both neural stem cells and cells that would develop into muscle and fat. The cells continued dividing for the six months the experiment took place and researchers believe it is likely they would proliferate indefinitely.

Much more research, however, will be needed before the cells can be used for clinical treatments. Before such cells could be implanted into human beings, doctors would need to be sure the neural stem cells would not develop into other types of cell in the body.

Several pharmaceutical companies have expressed interest in using the cells to test the toxicity and effectiveness of new treatments.

Freda Miller, the professor of molecular and medical genetics, who carried out the research, said: “This is very exciting because most tissue was not thought to have stem cells in them. However, we have been able to prove that stem cells can be created from skin and cultured without genetic modification. While this does not mean we do not need to do research into embryonic stem cells, it may mean that many more types of stem cell can be harvested using adult cells.”

Most scientists in the field believe adult stem cells, such as those created by Professor Miller’s team, will be useful in some clinical treatments, but that embryonic stem cells will have a much wider range of applications. They advocate a dual approach to research, in which both sources of cells are explored fully. Professor Miller said that the ultimate aim would be to treat spinal injuries or diseases such as Parkinson’s and Alzh eimer’s where existing cells have become irrevocably damaged.

However, she said that such advances were a long way off. She said. “You can’t put cells into the body without a million tests to show that are safe.While we believe these cells might develop in a certain way we have to be absolutely sure as the consequences would be devastating if, for example, stem cells turned into bone rather than neuron cells.”

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