Stem Cell Snag: Implanted Cells May Show Signs of Parkinson's
Barry, Patrick, Science News
For the first time, researchers have found evidence that Parkinson's disease might spread to healthy nerve cells implanted into a patient's brain.
In postmortem studies, researchers found that a small minority of implanted cells in three patients had acquired traits associated with the disease. But for five other transplant recipients, the implanted neurons appeared healthy and functioning at the time of death, up to 16 years after surgery.
The finding could have implications for the use of stem cells to treat Parkinson's. These proposed therapies would implant healthy nerve cells into a patient's brain to replace cells damaged by the disease and partially relieve symptoms, mainly the poor control of body movement characteristic of Parkinson's. Doctors would derive new nerve cells from embryonic-like stem cells, rather than taking nerve cells from human fetuses, as was done for the patients in the new studies.
Healthy survival of most of the implanted neurons bodes well for the stem cell approach, comments stem cell-therapy researcher Viviane Tabar of the Memorial Sloan-Kettering Cancer Center in New York City. But scientists need to understand why some cells unexpectedly developed Parkinson's-like conditions, she says.
"This goes to prove how little we understand Parkinson's disease," Tabar says. "I'm not closing my lab and giving up on stem cell therapies for Parkinson's. It's just an opportunity to learn more about how to do these therapies correctly."
In a trio of studies published online April 6 in Nature Medicine, scientists in Sweden, England, Canada and the United States searched the brains of the transplant recipients for cells that contained dumps of the protein alpha-synuclein. …