Early next year, a radical new treatment for Parkinson’s disease involving tissue transplants will receive its first trial with patients – including a group from the UK.
Stem cells grown in the laboratory and converted into nerve cells will be used to replace those destroyed by the disease. It is hoped that these will stop the spread of debilitating symptoms.
“It has taken a long time to get to this stage, but hopefully the results of these trials will mean that in a few years we may be able to offer tissue transplants as standard treatments for Parkinson’s,” said Professor Roger Barker, of Cambridge University. “It’s certainly a promising approach.”
In the UK, around 145,000 people live with Parkinson’s and around 18,000 new cases are diagnosed each year. The disease is triggered when nerve cells that supply dopamine to the brain begin to die due to a combination of genetic and environmental factors.
Dopamine helps a person control movement. When the supply falls, the result is tremors, stiffness, depression and other symptoms that can end up with patients using a wheelchair or bedridden. The progress of the disease can be slowed by the drug L-dopa, which replaces some of the lost function of dopamine cells. Treatments become less effective over the years. Researchers have been looking for new approaches for years.
One idea has been to replace dying dopamine cells with unaffected versions, which has been tried by several centers around the world. This initially involved the use of tissue from aborted fetuses that had been donated for medical research.
Fetal tissue contains dopamine-producing cells that can supply the missing chemical, although at least six or seven fetuses are needed to provide sufficient material for one patient. In trials in Europe, these cells were injected into patients’ brains with encouraging results. However, other studies in the US found such treatments to be far less effective.
The use of tissue from aborted fetuses was opposed by many on religious grounds. It was also difficult to obtain enough supplies for widely used treatments. However, Barker and his team at Cambridge – in collaboration with researchers led by Prof Malin Parmar at Lund University in Sweden – have developed a technology that avoids these problems.
The new approach uses stem cells, from which all cells with specialized functions are generated in the human body. These stem cells can be grown in laboratory cultures. Even better, scientists have learned how to transform them into dopamine cells. These will form the core of the transplants to be carried out next month.
“We now know that putting dopamine cells in the brain will work, and the procedure is safe,” Barker said. “There is no longer a problem with the supply of sufficient tissue because we can produce these cells in large numbers in the laboratory. The cost is relatively low. A supply of dopamine cells – made from stem cells – has become a standardized product, and we have no contaminating cells, as you can get with fetal tissue.
“This means that we are now at a point where we can use stem cell transplants as treatments for Parkinson’s patients, although it will take several years before we know that these work and can be used as standard treatments for Parkinson’s disease.”
Trials will begin over the next few months and will continue over the next year. There will be four participants from Sweden and four participants from Great Britain. “The cells are in a freezer and ready to go in,” Barker said. – The transplants will be done in Sweden because they have the instruments to perform this. This will be followed up during the year with further attempts.”
Researchers expect their experiments to take at least two years to complete. They will be followed by careful scrutiny of the results and any side effects. Provided these proceed satisfactorily, tissue transplants could be ready for wider use in about five years.
“Younger patients will benefit the most from this treatment,” Barker said. “It’s going to be a one-time treatment, so the complications you get with chronic medications won’t occur, while the advanced therapies involving deep brain stimulation won’t be needed as often.”