Stem Cell Culture System Helps Show How Alzheimer’s and Parkinson’s Diseases Spread Across the Brain

Findings may point to new direction for treatment research

Working with stem cells in the laboratory, scientists are discovering how Alzheimer’s and Parkinson’s diseases are spread from neuron to neuron across the brain, prompting widespread destruction of brain cells. The findings were presented November 18 at Neuroscience 2014, the annual meeting of the Society for Neuroscience and the world’s largest source of emerging news about brain science and health.

“Toxic proteins accumulate and are packaged within one neuron, and that package is released into the gap between neurons where it can be taken up by another neuron,” explained lead author Martin Hallbeck, PhD, of Linkoping University in Sweden. “We can now use this new knowledge, together with new model systems, to search for drugs that can block the progression of neurodegenerative diseases.”

Today, only symptomatic treatments are available for Alzheimer’s and Parkinson’s diseases . In both diseases, research indicates that bundles of toxic proteins — called oligomers — damage cells and act as seeds for the formation of additional bundles, spreading the damage across the brain and causing progressive degeneration of brain function. Recent studies suggest that oligomers are transferred from one neuron to the next, but it was unclear how this transfer takes place.

To solve this puzzle, Hallbeck and his colleagues used stem cells obtained from healthy adult human cells. They induced these cells to develop into neurons that could be grown and studied in the laboratory. The researchers then fluorescently tagged the two oligomer types involved in Alzheimer’s and Parkinson’s disease s . Tracking the fluorescent oligomers in the cell culture, the y discovered that the oligomers are packaged in tiny vesicles, called exosomes, which are released into the gap between neurons. Once there, the exosome and its toxic protein passenger are taken up by another neuron, spreading disease.

The researchers also found that transfer between neurons could be prevented by using a small molecule that inhibits the uptake process — a finding the points to a potential new class of drugs that could be developed to block the continuous cognitive deterioration of neurodegenerative diseases.

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Society for Neuroscience press release