Brain Transplanted Dopamine Cells Develop Parkinson's-Like Changes
A new groundbreaking study published in Nature Medicine has implications for the future of transplantation and stem cell therapies as a treatment for Parkinson's disease.
The study also provides a critical clue into the nature of Parkinson's disease itself. Researchers at Mount Sinai School of Medicine and Rush University Medical Center have discovered that dopamine cells that have been transplanted into the brain of patients with Parkinson disease develop pathologic changes characteristic of Parkinson's disease (Lewy bodies) and do not appear to function normally (reduced staining for dopamine transporter).
Researchers were able to perform an autopsy and study brain tissue from a patient who received a dopamine transplant 14 years earlier. "We found that newly implanted dopamine cells can also be affected by the Parkinson's disease process," said Dr. C. Warren Olanow, M.D., F. R. C. P (C), Professor and Chairman of Neurology and Director of The Robert and John M. Bendheim Parkinson's Disease Center at Mount Sinai School of Medicine. "Dopamine cells are transplanted into the brain of PD patients in the hope that they can replace those that degenerate and thereby improve symptoms of the disease. This study shows that implanted cells can become affected by the disease process and thereby limits the long-term utility of this approach."
In the study, the patient improved initially but then deteriorated. These findings have important implications for the use of stem cells as a treatment for Parkinson's disease. According to researchers, these new findings also have important implications on what causes PD. It argues against the theory that PD is due to a single event like an infection which causes initial damage to cells triggering their gradual degeneration over time. Rather, these findings suggest that the disease process is ongoing and can damage newly implanted cells.
"While, on the one hand, these results may sound disappointing, this information is crucially important if we are to develop better therapies for PD. The more knowledge we gain about the nature of the disease, the better our chances to find the cause of why cells degenerate and to develop a treatment that can protect them," said Dr. Olanow. "These findings also do not mean that transplant strategies such as stem cells can not be made to work - our findings just represent another obstacle that will have to be overcome".
Current treatments for managing Parkinson's disease include various medications and surgery, including Deep Brain Stimulation or DBS. Parkinson's disease is a movement disorder that is chronic and progressive, with symptoms continuing and worsening over time. Common symptoms include tremor of the hands, arms, legs, jaw, face rigidity or stiffness of the limbs and trunk, slowness of movement and impaired balance and coordination.