Cloned cells raise hopes of cure for Parkinson's

Therapeutic cloning can be used to treat brain diseases such as Parkinson's and Alzheimer's, scientists have discovered. Symptoms of a Parkinson's-type disease in mice were alleviated when their brains were injected with cloned cells.

The breakthrough is a significant step towards tackling degenerative and incurable brain disorders. It gives hope to the millions of people who suffer from such diseases, and supports the arguments in favour of allowing therapeutic cloning to be used in medicine.

Parkinson's disease is caused by the loss of cells that generate dopamine, a chemical messenger. Although rigidity and shaking can be alleviated with drugs, there is no cure. The actor Michael J Fox and the Pope suffer from the disease.

American researchers infected the brains of mice with the Parkinson's-like disease, then took cells from their tails. These were used to mass produce unlimited numbers of genetically matched dopamine nerve cells in the laboratory.

From these, the scientists were able selectively to develop neurons specific to the forebrain, midbrain, hindbrain and spinal cord. Neurons were also generated from stem cells taken from embryos made by traditional fertilisation.

Dopamine-producing neurons were then transplanted into the brains of mice with Parkinson's symptoms. The treatment produced a "robust alleviation" of symptoms, the researchers said.

Dr Lorenz Studer, from the Memorial Sloan-Kettering Cancer Centre in New York, wrote in the journal Nature Biotechnology: "Our results ... demonstrate the potential of therapeutic cloning in mouse models of Parkinson's disease.''

Scientists hope one day to manufacture dopamine neurons from stem cells - the body's "master'' cells, which can be programmed into different kinds of tissue. One way of achieving this would be to clone early-stage embryos from one of the patient's own cells. Stem cells from the embryos could then be used to produce dopamine neurons that genetically match the patient.

The next step will be to clone stem cells from human embryos and develop them into a treatment for Parkinson's. The Roslin Institute in Edinburgh has a licence to do the stem cell research.