STEM cell therapies for human brain diseases may have come a step closer, after monkeys with symptoms of Parkinson鈥檚 disease showed marked improvement following a single injection of neural stem cells.
To recreate the symptoms of Parkinson鈥檚 in African green monkeys, Richard Sidman of the Harvard Institutes of Medicine in Boston and his colleagues injected them with a chemical that damages neurons that make dopamine, a neurotransmitter vital for controlling movement.
They then injected the monkeys鈥� brains with neural stem cells from human fetuses that had been miscarried at 13 weeks. A month later, the monkeys showed marked recoveries. 鈥淭hey could stand, walk, feed themselves, and had regained independent living,鈥� says Sidman.
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After around four months, the animals began to deteriorate, probably because the cells were being attacked by the monkeys鈥� immune systems. However, they were still much healthier than untreated monkeys (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0704091104).
Post-mortems showed that the implanted cells had dispersed throughout the brain to structures where dopamine is produced. Their primary role seemed to be in protecting the brain against further damage, rather than replacing damaged cells, as had previously been assumed.
The team now plans to see if immunosuppressive drugs and repeat injections can prolong the benefits over the longer term.
