Parkinson's disease is caused by the death of a small number of brain cells that produce an important chemical called dopamine. Without dopamine, patients literally cannot move. Most people with Parkinson's disease take drugs such as L-dopa to help replace the chemical deficiency and make it possible to walk and all the other aspects of normal life. The problem with the drug L-dopa is that it must be taken every few hours. Before drugs, patients cannot move. Within an hour, movement is possible but those may have become exaggerated and abnormal. That cycle of "off" and "on" characterizes the daily life of people with Parkinson's. To replace the dead cells, fetal dopamine cells have been transplanted into the brains of humans with Parkinson's disease since 1988. The transplanted cells survive in the brain without immunosuppression and can supply the brain with dopamine. In some patients, the transplants can replace the need for L-dopa. Because recovery of dopamine cells from aborted fetal tissue fragments is difficult, only 300 patients in the world have had transplants. To improve cell transplantation and make it available to the tens of thousands of patients who could benefit, a new source of cells must be developed. Human embryonic stem cells are likely to be that source. My laboratory has been doing research on Parkinson's disease for many years. I have developed and evaluated new treatments for the disease including brain transplantation of dopamine cells. With colleagues who share experience in neurotransplantation for Parkinson's disease and in stem cell research, we will produce dopamine neurons from human embryonic stem cells and transplant those cells into animals which have a condition similar to Parkinson's disease. If these human cells successfully treat animals, these same cells could be used to treat people with the disease. Under current regulations, federal government funds can be used only for research on a few embryonic cell lines developed before August 2001. All of those cell lines are contaminated by contact with mouse cells and are unsuitable for human therapy. Funding by the California stem cell initiative will make it possible to work with new cell lines that could ultimately be used for treating people. CIRM funding is essential to accomplish our goals.
Parkinson's disease cripples about one million people in the United States and at least 100,000 in California. The cost of the medication and doctor visits averages about $12,000 per patient per year. Even with effective drugs, patients have daily fluctuations in condition, sometimes they cannot walk at all and sometimes their arms and legs are flailing out of control. Human embryonic stem cells can be converted into the dopamine neurons that Parkinson patients need. If our research can show that transplants of these cells can improve Parkinson's disease in animals, then the same cells could be used to treat patients in California and around the world. The need for drugs could be eliminated. The improved quality of life and the savings in drug costs could be substantial. The biotechnology involved in generating these cells may provide additional economic benefit since cells will be manufactured in sophisticated laboratories.