Researchers say they have discovered a technique that can reverse symptoms of Parkinson’s disease in a mouse model of the disease.
They say the technique may represent a new approach to explore for the treatment of neurodegenerative conditions.
A major goal of regenerative medicine is to replace neurons lost during neurodegenerative disorders and promote the integration of new neurons into brain circuits.
For example, Parkinson’s disease is characterised by a loss of dopaminergic neurons in a region of the brain responsible for reward and movement.
Xiang-Dong Fu and his team at University of California San Diego School of Medicine, say their findings suggest certain brain cells called astrocytes can be turned into functional dopaminergic neurons using a single-step method.
The study published in Nature was conducted in isolated human cells and in mice.
Dr Fu said: “Researchers around the world have tried many ways to generate neurons in the lab, using stem cells and other means, so we can study them better, as well as to use them to replace lost neurons in neurodegenerative diseases.
“The fact that we could produce so many neurons in such a relatively easy way came as a big surprise.”
Astrocytes produce a protein which prevents them from becoming neurons.
Researchers say removing this protein converts them to fully functional neurons that repopulate the lost neuronal circuits, restore dopamine levels and rescue motor deficits in mouse models of Parkinson’s disease.
But they caution that further research is needed before the approach can be applied to humans.
The researchers administered the treatment directly to a part of the mouse’s brain, which is responsible for regulating motor control and reward behaviours, and the part of the brain that typically loses dopamine-producing neurons in Parkinson’s disease.
A control group of mice received mock treatment.
In the treated mice, a small subset of astrocytes converted to neurons, increasing the number of neurons by approximately 30%, the study suggests.
Dopamine levels were restored to a level comparable to that in normal mice.
By two different measures of limb movement and response, the treated mice returned to normal within three months after a single treatment.
They remained completely free from symptoms of Parkinson’s disease for the rest of their lives.
In contrast, the control mice showed no improvement.
Professor Tara Spires-Jones of the UK Dementia Research Institute at the University of Edinburgh and deputy director of the Centre for Discovery Brain Sciences, University of Edinburgh, said: “While the principle of this study is remarkable and promising, it is important to note that it was conducted in mice with group sizes from three to eight and there is a long way to go to translate this into a treatment for people.”
Robert Howard, professor of old age psychiatry, at University College London, said the findings were an “extraordinary scientific discovery”.
He added: “This opens up a completely novel avenue for development of treatments to ‘rebuild’ damaged brains in Alzheimer’s and Parkinson’s diseases.”