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Two new studies suggest that Parkinson's disease can potentially be treated with stem cells placed in a patient's brain. NPR's Jon Hamilton reports that the studies show that scientists are close to their goal of replacing damaged brain cells with healthy ones.
JON HAMILTON, BYLINE: Both studies are preliminary and small but also encouraging. Dr. Lorenz Studer of Memorial Sloan Kettering in New York was part of a team that gave 12 people either a low or high dose of stem cells. He says over the next 18 months, the team used a standard rating scale to assess symptoms like tremor.
LORENZ STUDER: You would expect every year to get two to three points worse. And actually, the high-dose group, they got about 20 points better.
HAMILTON: The low-dose group had a less dramatic benefit. A separate team in Kyoto, Japan, gave seven patients a different type of stem cell. Their symptoms also improved. In both studies, published in the journal Nature, transplanted stem cells began making the chemical messenger dopamine. It is the loss of dopamine-producing neurons that causes the tremor, slow movement, rigid posture and balance problems that make Parkinson's so disabling. Studer says the success comes after decades of painstaking research.
STUDER: For us, it's quite the exciting time, as you can imagine, being in the making for about three decades nearly and finally seeing some of the fruits of that work.
HAMILTON: Studer says one reason it's taken so long is that stem cells have the potential to become many different kinds of cells. He says it takes just the right mix of chemicals to produce a neuron that makes dopamine.
STUDER: Took us nearly 10 years to figure out the recipe, how to make specifically those dopamine cells. Took us another 10 years to have the product that we would dare to put actually into patients.
HAMILTON: The product is millions of what the team calls progenitor neurons. Dr. Viviane Tabar, a surgeon and stem cell scientist at Memorial Sloan Kettering, says these progenitor cells arrive frozen.
VIVIANE TABAR: So you just thaw them and suspend them in an approved medium.
HAMILTON: Until the patient is in the operating room. Then, Tabar says, the cells are injected into a structure found on both sides of the brain that is involved in movement.
TABAR: The idea is to place these neuron progenitors right where you need them to connect with other neurons in the brain.
HAMILTON: Tabar says that takes time. Also, she says, the cells are still maturing when they are injected.
TABAR: This is not an intervention where a patient expects immediate reward.
HAMILTON: But after weeks or months, Tabar says, PET scans showed that the transplanted cells were doing their job. Tabar says the results could signal the start of a new way of treating Parkinson's and perhaps other diseases.
TABAR: If we're missing neurons, we're able to replace them. And the full expectation is that these cells are not going to function as cells that just release dopamine. They're going to rebuild circuitry.
HAMILTON: There may be risks, though. Some earlier efforts to replace brain cells led to movement disorders, and in some patients, cancer. So Dr. Mya Schiess of UTHealth in Houston says it's important to monitor the transplanted dopamine neurons.
MYA SCHIESS: They're going to be there for a long, long time. And you will have to follow up to see if over time there is, like, tumor formation, something of that nature.
HAMILTON: Schiess also says stem cell transplants don't cure the underlying disease. Even so, she thinks they could offer new hope to many patients, including those who are no longer responding to drug treatment.
SCHIESS: Now we have tools that can intervene, and so we have the potential to really, really halt this disease in its tracks.
HAMILTON: The Food and Drug Administration has cleared the drugs maker, BlueRock Therapeutics, to conduct a larger trial that could lead to approval. It's scheduled to begin later this year.
Jon Hamilton, NPR News. Transcript provided by NPR, Copyright NPR.
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