Human stem cells treat Parkinson's disease in rats

In the first experiment of its kind, researchers used human stem cells to treat rats affected by symptoms of Parkinson's disease. The results are promising, with a reduction in symptoms and the absence of side-effects experienced by other studies.

The researchers, from Hadassah University hospital, Jerusalem, grew cloned human embryonic stem cells (ES cells) in the lab in such a way that they developed into specialist neurones. They then transplanted these cells into the brains of rats that had the degenerative brain disease used as a model of Parkinson's disease. This disease causes the rats to turn continuously, and also not to side-step when dragged sideways. After the transplant, these symptoms were significantly reduced.

In a previous study in the US, a team used fetal stem cells to treat human patients. Over-proliferation of the transplanted cells caused severe side-effects, including uncontrolled limb movement. The Israeli researchers found no evidence of such over-proliferation in this case and post mortem analysis of the rats did not find any cancerous growths, another potential side effect. But as the scientists kept the rats for just 12 weeks after the transplant, 'much longer studies are needed to ensure no tumours develop', points out Dr Roger Barker from the Cambridge Centre for Brain Repair.

Presenting the findings at the annual conference of the European Society for Human Reproduction and Embryology, Dr Benjamin Reubinoff said, 'we believe that these results are encouraging, and set the stage for future development that may eventually allow the use of ES cells for the treatment of Parkinson's disease.' Dr Miodrag Stojkovic, from the Institute of Genetics at Newcastle University, cautioned that 'development of treatments for humans is much more complicated'.

In a separate Parkinson's study, published last week in Archives of Neurology, researchers transplanted embryonic cells into the substantia nigra, an area of the brain destroyed by the disease. The research team, led by Dr Paul Gordon, found greater improvements in the treated patients compared with a control group, and Dr Roger Rosenberg, editor of Archives of Neurology, described the benefits as 'small but definite'.