Stem cell hope for Parkinson's disease

A Japanese team of researchers has used embryonic stem cells to successfully repair the brain damage caused by Parkinson's disease in monkeys. The team, based at Kyoto University, used monkey embryo stem cells to produce nerve cells, which they transplanted into the brains of monkeys affected by a primate model of the disease. The treatment reduced the symptoms of the disease, raising hopes for a new therapy for human patients. However, the scientists, who published their findings in the Journal of Clinical Investigation, stress that further research into the long-term safety and effectiveness of the technique is needed before human trials can be considered.

People with Parkinson's disease are affected by tremors, stiff muscles and slow movements, caused by a gradual loss of dopamine-producing nerve cells in an area of the brain controlling movement. Researchers are hoping to develop new treatments for the illness, based on replacing these lost cells. One possible source of new brain cells is to use embryonic stem cells, which have the potential to grow into any type of body cell.

The Japanese scientists used stem cells taken from early monkey embryos, and grew them into dopamine-producing brain cells in the laboratory. They then transplanted the cells into monkeys who had Parkinson's disease-like brain damage, caused by a chemical called MPTP. The cells began to work correctly, and improved the monkeys' symptoms - particularly their posture and movement.

In a commentary accompanying the study, J William Langston of the Parkinson's Institute in California called the findings 'encouraging', but cautioned that 'the number of surviving dopamine-producing neurons was very low'. He added that 'it is good news that tumours were not observed, but this could also be related to the small number of surviving cells'. Only one to three per cent of the transplanted cells survived, compared to the estimated ten per cent that survive after fetal cell transplants. But Langston concluded that the study 'will advance research aimed at validating the use of stem cells to treat neurodegenerative disease'.