A team of Japanese scientists made the prediction after successfully restoring nerve cells destroyed by a similar condition in monkeys.
The animals, suffering an artificially induced version of the disease, showed significant improvement two years after having precursor dopamine neurons, derived from human stem cells, transplanted into their brains.
In humans, Parkinson’s causes progressive loss of the neurons, which release the vital nerve transmitter chemical dopamine necessary for controlling body movement.The scientists say they are now just a short step away from testing the treatment, based on laboratory-made stem cells called induced pluripotent stem (iPS) cells, in clinical trials.
They hope to start looking for suitable patients within the next 15 months.
Dr Tilo Kunath, a Parkinson’s UK-funded researcher at the Medical Research Council Centre for Regenerative Medicine at the University of Edinburgh, said: “This is extremely promising research demonstrating that a safe and highly effective cell therapy for Parkinson’s can be produced in the lab.
“Such a therapy has the potential to reverse the symptoms of Parkinson’s in patients by restoring their dopamine-producing neurons. The next stage will be to test these therapies in a first-in-human clinical trial.
“As a side-note, the fact that the researchers have used induced pluripotent stem cells instead of human embryonic stem cells (hESCs) means that this therapy can be used in any country worldwide.
“Some countries, such as Ireland and most of South America, have banned the use of hESCs as a therapy.”
The new study involved 11 macaque monkeys displaying Parkinson’s-like symptoms of tremors and impaired balance caused by a neurotoxin.
Some of the monkeys were given dopamine neuron progenitors grown from iPS stem cells derived both from human Parkinson’s patients and healthy donors.
Once transplanted the precursor cells matured and started to release dopamine, resulting in the restoration of movement control.
“Our research has shown that DA (dopamine) neurons made from iPS cells are just as good as DA neurons made from foetal mid-brain, said Prof Takahashi.
“Because iPS cells are easy to obtain, we can standardise them to only use the best iPS cells for therapy.”
Brain scans confirmed that the cells were functioning as expected and not triggering a damaging immune response.
A key finding from the research, published in the journal Nature, was that no tumours had appeared in the monkey’s brains – a recognised hazard of experimental stem cell therapies.
Each monkey was given just under five million progenitor neurons. However, the research showed that cell quality was more important than quantity.
Neurosurgeon Tetsuhiro Kikuchi, another member of the Kyoto team, said: “Each animal received cells prepared from a different iPS cell donor. We found the quality of donor cells had a large effect on the DA neuron survival.”