Embryonic Dopamine Cell Implants for Parkinson's Disease

The purpose of this trial is to determine if patients who received embryonic dopamine cell implant surgery showed significantly greater improvement in their Parkinson's disease than a control group undergoing the placebo treatment, and to determine if the cell implant surgery was more effective in younger or older patients.

Parkinson's disease is caused by the death of a small number of nerve cells that produce a critical chemical called dopamine. The drug L-dopa can partially make up for the lack of dopamine. As time goes on, however, most patients notice that the drugs do not work as well. Oftentimes, patients develop great fluctuations in motor control. Off drugs they cannot move, and on drugs they have excess, exaggerated movements. Research in animals over the last 20 years has shown that dopamine cells can be replaced by transplants of new cells obtained from fetal brain tissue. For the past 14 years, several laboratories around the world have been performing similar transplants of human fetal brain tissue on patients with Parkinson's disease. So far, it has been impossible to compare results from the different groups because no two centers are performing transplants in the same way. This study seeks to get around that problem using a controlled clinical trial that compares the embryonic dopamine cell implant surgery with a placebo treatment. A total of 40 patients were recruited--half received the cell implant surgery, while the other half received the placebo. After the double-blind phase of the study, patients in the placebo group had the option of receiving tissue implants. Fourteen of these patients eventually had transplants. At present, this study is providing long-term follow-up evaluation and treatment for the subjects.