Parkinson's Disease is a progressive disorder of the central nervous system. It occurs when the group of brain cells that produce an important chemical called dopamine begin to malfunction and eventually die. Dopamine is a neurotransmitter, or chemical messenger, that transports signals to the parts of the brain that control movement initiation and coordination.
In a patient suffering from Parkinson's, the dopamine-producing brain cells begin to die, for reasons that are still unknown. As a result, the amount of dopamine produced in the brain decreases. This causes various problems, including body tremors, rigidity or stiffness of limbs or trunk, slowed movement and impaired balance and coordination.
Some of the symptoms of Parkinson’s can be controlled with medications. However, no existing treatments provide a cure for Parkinson’s or reverse the damage it causes.
Human and Social Costs
An estimated one million Americans suffer from Parkinson’s Disease. One person in 200 will be diagnosed with Parkinson’s, and one out of 100 individuals over age 65 has the disease. Studies also show that about 10% of elderly people who pass away from a non-brain illness have pre-symptomatic Parkinson’s, indicating that there may be an additional 5 to 10 million people who are unaware that they are developing Parkinson’s.
The frequency of Parkinson’s Disease is highest in the over-60 age group, and the number of people who have the disease is expected to increase steadily as the Baby Boom population ages. In recent years, there has also been an alarming increase of younger Parkinson’s patients.
It is estimated that a Parkinson’s patient spends an average of $2,500 a year for medications. After factoring in office visits, Social Security payments, nursing home expenditures and lost income, the total cost of Parkinson’s in the US is estimated to exceed $5.6 billion annually.
Based on federal and state data, an estimated 5,500 Kansans currently suffer from Parkinson's Disease, and that the number of Parkinson's patients will increase 23% by the year 2030. It is estimated that the direct health care costs and indirect social costs (lost work time, etc.) associated with Parkinson's will cost Kansans tens of millions of dollars in 2005 – and more than a billion dollars over the next 25 years.
The Potential for Stem Cell Cures
More than 50 years of research on adult stem cells, taken from adult tissues, has produced such lifesaving treatments as bone marrow transplants for leukemia patients. And, adult stem cells are likely to provide additional cures for some diseases in the years ahead.
However, the new frontier in stem cell research involves early, or “embryonic,” stem cells (ES cells). Unlike adult stem cells, ES cells have the potential to turn into and regenerate any type of cell or tissue in the human body. As a result, ES cells could provide cures for many currently incurable or common diseases and injuries that cannot be cured with adult stem cells, or more effective treatments than adult stem cells may provide.
There are two basic sources of ES cells for such potential therapies. One source is the leftover embryos at fertility clinics that would otherwise be discarded and destroyed. ES cells can also be produced with Somatic Cell Nuclear Transfer (SCNT), a process that uses a patient’s own cells and an unfertilized human egg to make ES cells. SCNT has the added advantage of producing ES cells that will automatically match the patient’s genetic makeup. As a result, SCNT avoids the need to find a genetically matching donor and the problem of immune system rejection, two limitations associated with donated adult and ES cells.
Recent research indicates that transplants of ES cells or neurons produced with ES cells could help alleviate the symptoms of Parkinson’s and may provide the hope for a cure.
Animal studies have already shown that ES cells can be transformed into healthy dopamine-producing brain cells. One of the first groundbreaking studies on this front was conducted by scientists at the Memorial Sloan-Kettering Center in 2003. That study demonstrated that transplantation of dopaminergic neurons derived from cloned mouse stem cells can significantly improve the condition of “parkinsonian mice” (i.e., mice that have Parkinson’s-like symptoms).
In another animal study conducted by researchers at the Harvard Medical School, stem cells repaired the injured nerve cells of aged mice whose brains were compromised by the equivalent of Parkinson’s disease. And, in January 2005, a study by Japanese scientists found that ES cell transplants reversed Parkinson’s symptoms in monkeys.
Much more research is needed to determine if any type of stem cell transplants will provide a way to alleviate or cure Parkinson’s disease in humans. But it is clearly a promising new possibility and, for future stem cell transplant therapies, ES cells offer some key advantages.
In addition, SCNT has given medical researchers a method of growing cells that have the defects associated with a disease in a laboratory setting. This use of SCNT provides new ways to study how a disease like Parkinson’s progresses at the cellular level and to test the effectiveness of new drugs or other treatments that may cure or slow the progress of the disease.
The consensus of the medical and patient community is that all types of stem cell research should be pursued in the effort to find cures for diseases like Parkinson’s, and that ES cells can play an important role in this effort.
That’s why ES cell research is strongly supported by the overwhelming majority of medical researchers; medical organizations like the American Medical Association; disease and patient advocacy groups like the Michael J. Fox Foundation for Parkinson's Research, Parkinson’s Action Network, Take Charge! Cure Parkinson’s, American Parkinson’s Disease Association, Parkinson’s Disease Foundation, Parkinson’s Institute – and by well-known stem cell advocates who suffer from Parkinson’s like Michael J. Fox and Muhammad Ali.
Links to More Information:
Parkinson’s Action Network
Overview of the Somatic Cell Nuclear Transfer by the Parkinson’s Action Network
Testimony submitted by the Michael J. Fox Foundation for Parkinson’s Research to the President’s Council on Bioethics
Take Charge! Cure Parkinson’s, Inc.
American Academy of Neurology and American Neurological Association statement supporting SCNT and other forms of stem cell research
“Research Shows Therapeutic Cloning Can Cure Parkinson’s-like Disease in Mice.”
Memorial Sloan-Kettering Cancer Center
“Parkinson’s Disease: Stem Cell Promise.”
“Stem cells reduce brain damage: May replace, protect injured tissue.”
Harvard University Gazette
“Stem cells reverse Parkinson’s in monkeys.”
Sloan-Kettering Institute Research Shows SCNT Technique Offers Hope for Treating Neurological Disorders
Memorial Sloan-Kettering Cancer Center
“Therapeutic cloning studied for Parkinson’s.”
“Rebuilding the Nervous System with Stem Cells.”
The National Institutes of Health
“The latest research on stem cells and Parkinson's disease.”
U.S. Census Bureau
State of Kansas, Division of the Budget