Stem cells restore neurons in monkey model of Parkinson's disease

Neurons derived from human stem cells have successfully been used to treat and relieve symptoms of Parkinson's disease (PD) in a primate animal model.

The dopamine-producing neurons, which are preferentially lost in the disease, were generated from induced pluripotent stem cells from the skin and blood of healthy volunteers and PD patients.

Critically the study, published in Nature, found no evidence of tumour formation (a well-known risk for stem cell therapies) as late as two years after transplantation. The authors also confirmed the transplanted neurons integrated into the monkeys' neural networks, and behaved in a similar way to the host neurons.

Professor Jun Takahashi at Kyoto University, Japan, senior author of the study, described how 'the monkeys became more active after cell transplantation: moved more rapidly and more smoothly, and showed more various type of movements and less tremor'.

'In the primate model, these new transplanted cells effectively replaced those that are typically lost within the brains of people affected by Parkinson's – showing very promising results for transplantation as a possible treatment for the condition,' said Professor David Dexter, deputy research director at Parkinson's UK in London, who was not involved in the research.

The dopaminergic neurons typically lost in PD cause patients to have difficulty initiating movement and develop a consistent baseline tremor, both of which are very debilitating.

Professor Dexter explained: 'Current medication only serves to mask the symptoms of the condition, but makes no changes to the brain cells themselves. These studies show that, should brain cell transplantation become a viable therapy, it has the potential to reverse Parkinson's by replacing the dopamine cells that have been lost – a groundbreaking feat.'

After the success of this pre-clinical study, the authors hope to design and initiate a human clinical trial within the next 15 months.