Parkinson’s Patients who received fetal cadaver tissue grafts and whose brains were studied after they died, showed that the disease continued to affect healthy tissue and thus cell grafts may not function long term. From the story:
In other trials, fetal cells proved to cause so many side effects in some patients that they never were developed into a regular treatment for Parkinson’s.
“These findings give us a bit of pause for the value of cell replacement strategy for Parkinson’s disease,” said [study lead author Jeffrey] Kordower. “We still need to vigorously investigate this approach among the full armament of surgically-delivered Parkinson’s disease therapies. While it is not clear to us whether the same fate would befall stem cell grafts, the next generation of cell replacement procedures, this study does suggest that grafted cells can be affected by the disease process.”...
The individual described in this article was a woman with a 22-year history of Parkinson’s disease who underwent transplantation in 1993. After transplantation she experienced improvements in disease symptoms as measured by the Unified Parkinson Disease Rating Scale (UPDRS) and required substantially lower doses of antiparkinsonian medications. Her UPDRS scores remained improved into1997, but by 2004, she experienced progressive worsening of Parkinson’s disease symptoms. She died in 2007 and her brain and that of two other patients in the study were comprehensively processed and analyzed. She had the longest survival after transplantation that had been reported to date among this study’s participants.
In any event, this is why I am generally hesitant to speak of “cures” when speaking of stem cell-related regenerative medical experiments, preferring the word “treatment,” since as a non scientist observing the scene, it seems to me that the studies show amelioration of symptoms more than cures.
This is no small thing, of course. Take the example of Dennis Turner. He received a treatment for Parkinson’s with his own neural stem cells to apparent great effect for several years. His level of medication reduced. He was able to lead a vigorous life at a time when he had expected to be disabled. But eventually, the symptoms of his Parkinson’s returned, just like the patient mentioned in the study.
It could be that some of these diseases may remain chronic conditions with repeated cell infusions a standard method of keeping the worst symptoms at bay. Time will tell, but I can think of a lot worse scenarios.