Parkinson’s Disease


Parkinson’s disease (PD) involves the malfunction and death of vital brain cells, or neurons, in a specific area of the brain called the substantia nigra. [1] The substantia nigra is a production center of a chemical called dopamine, which is important in sending messages to other parts of the brain that control movement and coordination. As the disease progresses, the amount of dopamine produced in the brain decreases, leaving a person unable to control movement normally. At the same time, deposits of sticky proteins, called Lewy bodies, form in the substantia nigra and other brain regions—one of the hallmarks of PD. Parkinson’s disease is a chronic and progressive movement disorder, meaning that symptoms continue and worsen over time. The cause of PD is unknown, though in rare cases, PD can be caused by genetic mutations or exposure to certain environmental toxins.

As many as one million Americans live with Parkinson’s disease, which is more than the combined number of people diagnosed with multiple sclerosis, muscular dystrophy, and Lou Gehrig’s disease. [2] Approximately 60,000 Americans are diagnosed with Parkinson’s disease each year, and this number does not reflect the thousands of cases that go undetected. [3] The incidence of Parkinson’s increases with age, but an estimated four percent of people with PD are diagnosed before the age of 50. [4] Men are one and a half times more likely to have Parkinson’s than women. [5] Although there are treatment options such as medication and surgery to manage the symptoms of the disease, there is presently no cure.

The combined direct and indirect cost of Parkinson’s, including treatment, social security payments, and lost income from inability to work, is estimated to be nearly $25 billion per year in the United States alone. [6] Medication costs for an individual person with PD average $2,500 a year, and therapeutic surgery can cost up to $100,000 dollars per patient. [7]

Progress towards a cure

With more than $44 million in funding from Proposition 71 and the California Institute for Regenerative Medicine (CIRM), California’s stem cell scientists are making progress to better understand Parkinson’s disease, and to translate those discoveries into new therapies. [8]

CIRM scientists are taking two general approaches to understand and treat Parkinson’s Disease. The first approach involves using stem cells as a model of the disease in order to understanding the underlying causes and to screen for effective therapies. The second approach involves creating dopamine-producing cells with the hope of replacing the neurons that are damaged in people with PD. [9]

CIRM scientists have taken skin cells from people with Parkinson’s disease, reprogrammed them back to pluripotent stem cells, and then coaxed those pluripotent cells to become the type of neuron that is affected by Parkinson’s disease. [10] This is known as a stem cell model of the disease. This system gives scientists new insight into neurological diseases, as animal models do not often display the same types of neurological defects that humans with PD do. Several groups have pursued this strategy to better understand what is going wrong in the cells of Parkinson’s patients. There are several groups in California that have used this stem cell model to uncover the role of mitochondria, the power plant of the cell, in the cellular dysfunction of Parkinson’s disease.

The ability to study human Parkinson’s disease cells in a lab dish is a major milestone: this means that stem cell scientists can screen thousands of different drugs to identify those that eliminate signs of the disease in these cells. [11] Until the advent of pluripotent stem cell technology, there was a bottleneck in the understanding of Parkinson’s disease as there were few reliable cellular models of PD. If scientists can find drugs that treat the disease in a lab dish, they can then test those same drugs in animals, developing the most promising candidates into therapies. Several teams of CIRM-funded researchers are using stem cell techniques to create Parkinson’s disease cells in the lab dish and then screening them for new drugs.

Other groups in California and elsewhere are creating dopamine-producing cells in the lab dish with the hope that they could replace the neurons that are damaged in people with the disease. [12] In fact, researchers have been able to transplant neural stem cells into non-human primates with Parkinson’s symptoms and shown that these cells develop and integrate properly into the brain. This is the first step in developing a safe therapy for patients with Parkinson’s disease.

Selected disease and research progress information provided by the California’s stem cell research funding agency, the California Institute for Regenerative Medicine (CIRM). Visit for more updates.

Featured Image: Photo Courtesy of the Salk Institute for Biological Studies.


[1] “What Is Parkinson’s Disease?”  2016.  Parkinson’s Disease Foundation.  Web.  Accessed 24 February 2016.

[2] “Statistics on Parkinson’s.”  2016.  Parkinson’s Disease Foundation.  Web.  Accessed 24 February 2016.

[3] Id.

[4] Id.

[5] Id.

[6] Id.

[7] Id.

[8] “Parkinson’s Disease Fact Sheet.”  California Institute for Regenerative Medicine.  Web.  Accessed 24 February 2016.

[9] Id.

[10] “Parkinson’s Disease Fact Sheet.”  California Institute for Regenerative Medicine.  Web.  Accessed 24 February 2016.

[11] Id.

[12] Id.


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