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Nanotech intervention disrupts characteristic rogue protein growth. Andrew Masterson reports.
An artist's impression of Lewy bodies forming inside a neuron during Parkinson's disease.
The scientists, led by Donghoon Kim from Johns Hopkins University School of Medicine in the US, report that the deployment of graphene quantum dots (GQDs) into brain tissue severely disrupts the aggregation of a protein called alpha-synuclein, thought to be a primary driver of the loss of neurons and synapses that characterise the disease.
GQDs are made from graphene, which comprises carbon atoms arranged in a hexagonal lattice. They can contain one or many layers, and range in size between 10 and 70 nanometres.
The material is a hot focus for research, because it is non-toxic in biological systems, stable in environmental systems, and exhibits predictable luminescence, making it attractive in areas as distant as medicine and electronics.
In a letter published in the journal Nature Nanotechnology, Kim and his colleagues report the results of introducing GQDs into the midbrains of test animals with Parkinson’s.
This is the region in which alpha-synuclein congregates, clumping into structures called fibrils. The fibrils form into lesions known as Lewy bodies, which are characteristic of Parkinson’s and a similar condition known as dementia with Lewy bodies (DLB).
The researchers report that the introduction of GQDs in test subjects inhibited the fibrilisation of the protein, and reduced synaptic loss and neuronal cell death. Moreover, they reduced Lewy body formation.
Because they are so small they could pass through the brain-blood barrier – a major obstacle for many medical molecules – and thus prevent the destruction by already formed alpha-synuclein fibrils of dopamine-producing neurons, potentially mediating one of the most distressing symptoms of the disease.
Although the work reported is preliminary, the results suggest that GQDs might not only slow the progression of Parkinson's, but may actually halt it.
Kim and colleagues measured the number and length of fibril segments in the midbrains of test subjects and found that they grew shorter and more numerous. The process began just six hours after the dots were introduced and peaked at 24. This, they suggest, indicates that larger fibrils were being broken up.
By the third day the number of fibril fragments started to decrease, and were undetectable by day seven.
There is still much work left to be done, but the scientists end their letter on a cautious but distinctly optimistic note.
“It is expected that GQD-based drugs with appropriate modifications might provide a clue to support the development of new therapeutic agents for abnormal protein aggregation-related neurological disorders including Parkinson’s disease,” they write.
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