Primate Parkinson’s Treatment Reveals New Side of Stem Cells
While most scientists are struggling to change stem cells into the types of cells they need — neurons, insulin-producing cells, heart cells, etc. — the new work shows that stem cells can perform the remarkable task of saving damaged cells.
[Researchers] injected stem cells taken from the brains of 13-week-old aborted human fetuses into African green monkeys with damaged dopamine-producing brain cells.
Dopamine is a neurotransmitter that affects motion and balance. The death of so-called dopaminergic neurons has been linked to Parkinson’s disease, an incurable neurodegenerative disorder that affects about one million Americans.
At the time of the injections, the monkeys couldn’t feed themselves or walk without assistance, and alternated between periods of absolute stillness and uncontrollable tremors. Two months after the treatment, they were able to walk and eat. The tremors had disappeared.
“The behavioral improvement was very impressive,” Langston said.
But far from turning into a mass of brand-new dopamine-producing neurons, most of the [stem cells] clustered around existing neurons, protecting them from further damage and rejuvenating those that had deteriorated.
Four months after the injection, the effects started to wear off. The transplants’ declining effectiveness over time may also indicate that the monkeys’ immune systems rejected them. That would require transplant recipients to take immunosuppressant drugs — but in a medical catch-22, the drugs could prevent the stem cells from working.