Japanese researchers have been able to improve the symptoms of Parkinson's disease in monkeys by transplanting nerve cells derived from embryonic stem cells into their brains, the team has announced.
The finding is the world's first reported success of its kind with a primate, according to the research team led by associate professor Jun Takahashi of Kyoto University's Institute for Frontier Medical Sciences. It has been released in the online edition of US journal Stem Cells.
After the transplant, the monkeys, which had been almost unable to move, showed improvements in their symptoms to the point where they became able to walk on their own, the team said.
Parkinson's disease is a neurological illness believed to be caused by a deficit of the neurotransmitter dopamine in the brain.
Embryonic stem cells, which have the potential to become almost any type of tissue, are harvested from inside a blastocyst, which develops from a mammalian egg cell about a week after it is fertilised.
Takahashi's research team used the embryonic stem cells to cultivate a cell mass in which 35 per cent of the cells were dopamine-producing neurons.
These neurons then were transplanted into the four crab-eating monkeys, whose conditions were observed over a one-year period.
According to the study, the monkeys exhibited reduced shaking of their limbs half a year later. They had remained nearly motionless inside their cages all day long before the transplant, but the improvement of their symptoms eventually enabled them to occasionally walk around the cages.
The research team confirmed that normal nerve cells had been created in their brains.
The finding could mark a major breakthrough for applying embryonic stem cells in clinical settings, experts said. The Health, Labour and Welfare Ministry has been encouraging researchers to study the clinical applications of not only stem cells, but also induced pluripotent stem cells, which also can grow into many kinds of human cells.
Takahashi's team has already performed experiments to transplant iPS cells into monkeys' brains.
"We'll make further efforts to enhance the safety of these cell transplants," Takahashi said. "And we hope to start clinical application studies as early as three years from now."
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Japanese researchers find stem cells reduce monkeys' Parkinson's symptoms