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Scientists are working on a radical treatment for Parkinson's. It involves transplanting healthy brain cells to replace cells killed off by the disease. The approach was first tried nearly 20 years ago with mixed results. NPR's Jon Hamilton reports on why researchers think it's time to try again.
JON HAMILTON, BYLINE: Parkinson's destroys brain cells that make a substance called dopamine. Without enough dopamine, people develop tremors, difficulty walking and a range of other symptoms. Claire Henchcliffe, a neurologist at Weill Cornell medical college in New York, says drugs and other treatments are helpful to a point. But she says a better approach would be to replace the brain cells that Parkinson's is killing.
CLAIRE HENCHCLIFFE: The rationale is that, well, if those cells are lost and we know they make dopamine and we know that dopamine is important for good coordination, good automatic movement, why could we not replace those cells?
HAMILTON: In the 1980s and '90s, researchers actually tried that. They took brain cells from aborted fetuses and injected them into an area of the brain affected by Parkinson's. The hope was that these cells would begin producing enough dopamine to halt or even reverse symptoms. But the results were uneven. Many patients did not get better and some developed uncontrollable movements. So in 2003, Henchcliffe says, doctors stopped doing transplants.
HENCHCLIFFE: There was a stepping back to re-evaluate what exactly just happened.
HAMILTON: That took a while. But now it's clear that over the long term some patients really were helped by the procedure. Henchcliffe herself got to examine five people who'd received transplants more than 15 years earlier.
HENCHCLIFFE: These were patients with decades of Parkinson's disease. And I thought it was really striking that for a subset of these patients they actually seemed to be doing much better than one would expect.
HAMILTON: So researchers have been looking for ways to make cell transplants safer and more effective. And now, thanks to some remarkable advances in stem cell technology, they think they've done it. This week Henchcliffe and several other prominent researchers described their plans to revive the surgery during a session at the International Society for Stem Cell Research meeting in Boston. Another speaker was Viviane Tabar, a neurosurgeon at Memorial Sloan Kettering Cancer Center in New York. Tabar says one problem with those early transplants was that the cells came directly from fetuses.
VIVIANE TABAR: What you were placing in the patient was just a soup of brain. It did not have only the dopamine neurons which exist in the tissue but also several different types of cells.
HAMILTON: Some of those other cells may also have grown in the patients' brains, causing side effects. So for the past dozen years, scientists at Sloan Kettering have been developing a method to grow just dopamine cells in the lab. Tabar says these cells are an exact replacement for the neurons that produce dopamine in an adult brain. And the supply is unlimited.
TABAR: Not only can we grow them, in fact, we have almost a thousand doses of these cells already sitting in a freezer.
HAMILTON: Tabar, along with her colleague and husband Lorenz Studer, hope to begin transplanting those cells into Parkinson's patients next year. Both have a financial stake in a company that's funding the project. And several other groups in Europe, California and China are also launching transplant studies. Tabar says the time is right.
TABAR: On the one hand, you don't want to rush. On the other hand, I think the field is ready for something bold.
HAMILTON: Jon Hamilton, NPR News.
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