KYOTO -- Japanese researchers begin clinical trials Wednesday to treat Parkinson's disease with tissue grown from stem cells, hoping to apply for approval for the method as soon as 2022.
A Kyoto University team led by professor Jun Takahashi told reporters on Monday that testing using induced pluripotent stem cells, or iPS cells, has been greenlighted by Japan's government.
Made from adult tissue, iPS cells are reprogrammed to what is essentially an embryonic state, from which they can give rise to any type of body cell. Kyoto University biologist Shinya Yamanaka shared a 2012 Nobel Prize for his research on the reprogramming mechanism.
This marks Japan's first clinical trial of an iPS treatment in an area covered by national health insurance.
The test involves injecting 5 million nerve cells derived from iPS cells into the patient's skull. The transplanted cells are supposed to produce dopamine, a chemical messenger that relieves Parkinson's symptoms.
"This will be a verdict on our accumulated research," Takahashi told reporters.
Parkinson's patients typically take oral dopamine medication, but the benefits of this treatment subside after a decade or more. Adding dopamine-secreting cells to the regimen could prolong effectiveness, the scientists said.
Cells stockpiled by Kyoto University will be used for the tests, which will involve seven people, according to the plans.
The upcoming human trials follow groundbreaking transplants by Japanese research institute Riken that used iPS-derived retinal cells to treat age-related macular degeneration, a condition that leads to blindness.
Osaka University has won approval to conduct human trials to treat heart patients with iPS cells, and Keio University is researching using the same technology to treat spinal cord injuries.
Parkinson's, a debilitating disease that gained greater public awareness after American actor Michael J. Fox was diagnosed with it in 1991, afflicts over 160,000 people in Japan alone. The number is expected to rise with Japan's graying population, a challenge also faced by other Asian countries such as China and Thailand.
Testing on monkeys shows that iPS-derived nerve cells can improve impaired motor functions, but the effect on damaged cognitive ability and other symptoms is less apparent. The treatment would not fully halt the progression of the disease, in which the accumulation of a rogue protein in the brain apparently kills dopamine-producing cells.
The clinical trials approved in Japan are slated to last two years and will seek to ensure that patients do not develop cancers or other dangerous side effects.
Takahashi says he would like to see the cost of the Parkinson's treatment limited to "several million yen" (1 million yen equals $9,000).