Researchers have succeeded in improving the treatment of Parkinson's disease by using human embryonic stem cells to create nerve cells that produce dopamine and then transplanting the cells into monkeys' brains.
Four monkeys with Parkinson's disease — and previously unable to walk due to their symptoms — improved substantially after the human nerve cells were transplanted into their brains, reducing the shaking in their limbs and leading to some regaining the ability to walk, the research team, including Kyoto University professor Jun Takahashi, said Tuesday.
It is the first time pluripotent human embryonic stem cells have been successfully transplanted to improve symptoms of Parkinson's disease in monkeys, according to the team.
Parkinson's disease is linked to drops in the production of dopamine — a neurotransmitter in the brain. While there are drugs to treat the progressive neurological illness, there is currently no treatment to stop dopamine levels from falling.
In the study, the researchers transplanted nerve cells derived from the human stem cells into the four monkeys' brains. About three months later, all of them began to show improvements in their symptoms and tests conducted a year after the operation confirmed the nerve cells had been successfully grafted in their brains.
The finding holds much promise for the future treatment of Parkinson's disease in humans using regenerative medicine, but the researchers cautioned that a lot more work lies ahead as the study also showed that transplanted nerve cells that were not appropriately matured led to the development of tumors, although they were not malignant and could be treated.