Human brain cells with Parkinson's disease have been successfully grown in a Petri dish, allowing researchers to study them in unprecedented detail. American researchers used a technique in which human skin cells are transformed into induced pluripotent stem (iPS) cells, which can then be made to change into any cell type - in this case, neurons.
In the study, published in Nature Communications, skin cells were taken from two healthy donors and from two patients with a strain of Parkinson's disease that is caused by a mutation in the parkin gene. The neurons that resulted from the patients' skin cells possessed the same parkin mutation. The mutation is known to be the cause of the disease in about ten percent of Parkinson's patients; the cause in the remaining 90 percent of cases is unknown.
The work enabled the group to see how the parkin mutation causes Parkinson's. It will also allow researchers to investigate, up close, the effects of potential new treatments, and study other neurodegenerative diseases by observing neurons directly.
Study leader Dr Jian Feng, from the University at Buffalo in New York, said that this was the first time that brain cells had been generated from Parkinson's patients with parkin mutations: 'Before this, we didn't even think about being able to study the disease in human neurons. The brain is so fully integrated. It's impossible to obtain live human neurons to study'.
The parkin gene normally helps the brain control the levels of dopamine, a brain signalling chemical. When a mutation occurs an enzyme called monoamine oxidase (MAO), which is toxic to dopamine-producing cells, is produced uncontrollably, thereby killing neurons and causing Parkinson's disease.
'We found that when parkin is mutated, that regulation [of MAO] is gone, so MAO is [produced] at a much higher level', said Dr Feng. 'The nerve cells from our Parkinson's patients had much higher levels of MAO expression than those from our controls'.
Dr Feng said he hopes that the work will help further understanding of Parkinson's disease and develop new treatments: 'We suggest in our study that it might be possible to design a new class of drugs that would dial down the expression level of MAO'.