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News in Brief
Researchers from the Whitehead Biomedical Institute announced in the March 6 edition of Cell that they have succeeded in transforming the skin cells of five people living with Parkinson’s disease (PD) into dopamine producing neurons — the very cells that are lost in the brains of people with Parkinson’s.
The scientists, led by Frank Soldner, M.D., and Rudolf Jaenisch, M.D., took skin cells from five people with Parkinson’s between the ages of 53 and 85, as well as from two healthy individuals.
Using a process developed in the past two years, which injects viruses and genes into skin cells, researchers genetically programmed the cells back to a primitive state. These cells, called induced pluripotent stem cells (iPSCs), resemble human embryonic stem cells (hESCs) because of their capacity to turn into any type of cell in the body, but do not trigger the same ethical debates.
Researchers then reprogrammed these iPSCs to become brain cells — specifically the type of neurons that produce dopamine. This marks the first time that dopamine neurons have been produced from human skin cells. Drs. Soldner and Jaenisch say their method (and the ability of other researchers to replicate it) is primarily of value for what it can offer the study of Parkinson’s. Because the cells that the team produced originally came from people with PD, these cells should, in time, develop Parkinson’s too. (This would take years, so researchers will speed up the process using genes and chemicals). By watching Parkinson’s develop in brain cells, researchers will have the unique opportunity to study the progression of the disease.
Another possible future benefit is that the transformed cells could potentially be implanted in the brains of people with Parkinson’s as a cell replacement therapy. The neurons are young, healthy and still producing the dopamine that may ease the symptoms of PD. Since the cells are “patient-specific” — meaning that the person who donated the skin cells would receive their own transformed cells as a cell replacement treatment — there would be none of the issues of immune rejection that are presented with other cell treatments. Furthermore, the researchers were able to remove the viruses and genes used during the cell transformation process — another first-time accomplishment that will enhance the therapeutic potential of the cells.
The Whitehead team acknowledges that any potential therapies using these cells are in early stages of development. For now, they believe their method is an easy way for scientists to produce dopamine neurons that have PD in order to study the disease and to better understand it.
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According to a study published in the March 9 issue of Archives of Neurology, two medications commonly used to treat early-stage Parkinson’s disease (PD) offer similar long-term effects on PD’s motor symptoms and on quality of life.
Kevin Biglan, M.D., M.P.H., of the University of Rochester Medical Center, and his team enrolled 301 people with Parkinson’s in the study, from 22 sites in the US and Canada between 1996 and 1997. Each person in the study was randomly assigned to be treated initially with either levodopa only or pramipexole only.
Levodopa and pramipexole both treat the loss of dopamine in the brain that causes Parkinson’s symptoms. Levodopa is a substance that is converted into dopamine by an enzyme in the brain while pramipexole mimics the role of dopamine by binding to receptors in the brain.
To understand the long-term impact of these two medications upon people with Parkinson’s, Dr. Biglan and colleagues followed all 301 study volunteers for two years and then continued following 222 of the same volunteers for an additional four years. The researchers tracked participants for any changes in their PD symptoms, including dyskinesia (involuntary twisting and writhing movements), sleep habits, quality of life, depression and other adverse events.
Overall, the two groups scored very similarly on the United Parkinson’s Disease Rating Scale (UPDRS), which measures PD’s physical symptoms. Both also reported very similar levels of quality of life.
The study confirmed conventional medical wisdom about the differing side effects of the two medications. Those in the levodopa group more frequently experienced dyskinesias and “on-off effects” (when medication wears off before it is time for the next dose), while those taking pramipexole experienced a greater degree of daytime sleepiness. The findings demonstrate that whichever of these two medications is given first for the treatment of Parkinson’s, the results are very similar.
To learn more about medications available for the treatment of Parkinson's browse PDF's medication chart.