Stem cells aid Parkinson's in primates, but only temporarily

Author:  Corbaley Dean

Date:  July 2007

For the first time ever researchers were able to successfully use stem cells to treat Parkinson's disease in our closest relatives. primates. These results, released this month, show that stem cells can actually alleviate the damage caused by Parkinson's disease. The stem cells work in a very surprising way to do this, not only replacing damages neurons, but also rescuing and repairing pre-existing ones. This opens a whole new door in the quest for alleviating Parkinson's and curing neurological disorders in general.

Richard Sidman, a Harvard Medical neuroscientist, along with Yale University's Eugene Redmond and Evan Snyder of the Burnham Institute for Medical Research, injected stem cells into African green monkeys with damaged dopamine-producing brain cells. The researchers started the experiment with injecting stem-cells into the dopamine producing centers of the brains of monkeys who were, at the time, incapable of walking or feeding themselves. After two months, the monkeys could actually walk and feed themselves. However, four months after their recovery, the affects wore off. Autopsies showed that very few of the stem cells grew into the precious dopamine producing cells. Instead, most grew into astrocytes, cells that protect and support the depleted cells. The astrocytes helped protect the dopamine cells, but could only stave off their degeneration for so long and the Parkinson's continued to progress.

Parkinson's disease is a degenerative neurological disorder that usually affects humans in the late 40's of their life. Parkinson's severely affects motor control and usually begins with the trembling of hands and lips. Parkinson's can worsen to body tremors, difficulties in conscious movements, and finally result in incapacity or dementia in many cases. Dopamine, a neurotransmitter produced in the brain, plays an important role in controlling body movement. The low level of dopamine is one of the causes of Parkinson's.

How and why the stem cells grew into mostly support cells and not into actual dopamine producing cells is still being researched. "The adult brain is very different from the developing brain, to include its chemical make-up and development," explains Alison Willing, Ph.D., Associate Professor of Neurosurgery and Molecular Pharmacology and Physiology Center of Excellence for Aging & Brain Repair. "Some of the signals needed for a stem cell to grow into a specific portion of the brain may no longer be present in a fully matured brain."

- By Dean Corbaley.