Parkinson's Disease: Latest research and Treatments
There is no cure for Parkinson’s disease…yet. Until we understand exactly what causes the disease, the elusive cure is a long way off.
There are hundreds of research projects worldwide looking into all aspects of Parkinson’s and that research has made remarkable progress in recent years.
Fetal Cell Transplant
This is highly controversial because it involves the use of cells from aborted fetuses. These cells could be engineered to replicate any cells in the body, so in theory one day surgeons will be able to replace those lost through Parkinson’s.
Results in human studies have so far been varied. In some patients the results have been encouraging with a significant reduction in tremors, particularly in younger patients. However, some people have suffered serious adverse side effects including dyskeniesias (uncontrolled movements), while off their medication. Dyskeniesias is a common side effect of the widely used drug levadopa.
As a treatment, fetal cell transplant is still a long way off and the emphasis is on animal research to refine the technique. Scientists are looking at the use of fetal tissue from sources other than human embryos to dampen the controversy surrounding this method.
Stem Cell Research
These are parent cells of all the tissues in the body and, like fetal cells, could be turned into any type of cell including dopamine-producing neurons. These cells are harvested from adult bone marrow. Some researchers believe they are not as easy to work with as fetal cells and there is concern that people could suffer the side effect of dyskeniesias.
Researchers are also looking at using cells from the tissue at the back of the eye - retinal epithelial cells which produce and release dopamine (the neuro transmitter which is deficient in Parkinson’s patients). A small trial has already shown promise and this has now been extended.
Gene Therapy as a Possible New Treatment
This is not necessarily about replacing or repairing faulty genes but more about introducing different genes into the brain to deliver a variety of substances designed to act in various ways. It’s possible that faulty genes could be “turned off” or important proteins could be introduced into the brain to have a positive effect on Parkinson’s symptoms.
Researchers in England are investigating introducing two specific beneficial genes into the brain cells. One would help make the enzyme tyrosine hydroxylase, which is involved in dopamine production, while the other would make glial-derived neurotrophic factor (GDNF), which can help the neurons that are left in the brain to survive (see below). These genes are attached to billions of microscopic viruses, such as the herpes simplex virus which causes cold sores. The herpes virus naturally lies dormant in the nerve cells for a long period of time so any beneficial genes attached to it will also remain in the system.
So far research on animals has proved successful but far more work and experimental trials are needed before this technique can be widely tested on humans.
Glial-Derived Neurotrphic Factor (GDNF)
This neural growth factor encourages damaged cells to re-grow and produce more dopamine. It is pumped, via a small plastic tube, into the area of the brain that controls movement and is lacking in dopamine.
A small trial in Bristol, England, reported dramatic results with all participants showing a marked improvement in their symptoms.
This trial is now being followed by a more comprehensive study to see whether the results can be reproduced and whether GDNF would benefit all people with the disease.