Scientists Reverse Parkinson’s Disease In Mice By Inhibiting A Single Gene

Tremors are a main symptom of Parkinson's disease. Image: Photographee.eu/Shutterstock

A team of researchers from the University of California, San Diego, have achieved a landmark victory in the fight against dementia by developing a one-off treatment that appears to permanently cure Parkinson’s disease in mice. Describing their method in the journal Nature, the study authors are hopeful that the same process can one day be used to treat a wide range of neurodegenerative conditions in humans.

Parkinson’s and other forms of dementia occur when neurons become damaged and die, which is why scientists have spent decades attempting to come up with treatments to either protect these brain cells or generate new ones to replace those that are lost. Remarkably, the team behind this latest breakthrough were able to achieve this by altering a single gene.

Stage one of this discovery occurred in a petri dish, where the researchers tweaked the genetic code of non-neuronal brain cells called astrocytes. These are star-shaped cells that support communication throughout the brain, and produce a protein called PTB which ensures that they remain astrocytes and don’t transform into neurons.

Once the researchers blocked the production of PTB, however, a spectacular metamorphosis occurred as the astrocytes in the dish transformed en masse into neurons.

“What we've found is that forcing PTB to go away is the only signal a cell needs to turn on the genes needed to produce a neuron,” explained study author Xiang-Dong Fu in a statement.

Top: Mouse brain before reprogramming, with dopaminergic neurons shown in green. Bottom: Mouse brain after reprogramming with PTB antisense oligonucleotide treatment, which converted astrocytes into more dopaminergic neurons (green). UC San Diego Health Sciences

To test whether this principle could be applied to treat dementia in a living brain, the team induced Parkinson’s disease in mice using a substance that destroyed their dopamine-producing neurons. In humans, Parkinson’s occurs when neurons that produce dopamine stop functioning in part of the mid-brain called the substantia nigra.

The study authors then injected artificial DNA that blocked the production of PTB directly into the mid-brain of these mice, which caused astrocytes in this region to transform into new dopamine-producing neurons. Within 12 weeks of treatment, the rodents’ dopamine levels had returned to normal, leading to a complete cessation of tremors and other Parkinson’s symptoms.

Amazingly, the mice remained completely free of symptoms for the rest of their lives, suggesting that a single treatment may be all that is needed to fully reverse the disease. Commenting on this unprecedented outcome, Fu explained that “this whole new strategy for treating neurodegeneration gives hope that it may be possible to help even those with advanced disease.”

Naturally, it’s too early to assume that this principle will apply equally to humans, and doctors won’t be injecting any artificial DNA into the brains of any Parkinson’s sufferers. However, with a little more research it may be possible to develop new treatments to spark the creation of new neurons in the brains of people suffering from dementia and other forms of neuronal damage.

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