Nearly 30 years ago, the novel treatment which propel me into medicine but not just medicine but neurology and Parkinson’s disease was fetal brain transplantation into PD person’s brain in an attempt to halt disease. After several decades the procedure was banned here in the States and an unofficial moratorium was placed elsewhere on this type of trial. For those 300 plus patients which did receive this “novel” treatment, the results were a mixed bag. While the procedure showed some improvement in younger and less severely affected Parkinson’s patients, “many patients experienced off-drug ‘runaway‘ dyskenesias which resembled a lot like chorea at times. These patients then had to be treated with Tetrabenazine, Reserpine as well as pallidotomies and DBS to attempt to control symptoms.
Now, using a different technique by researchers with a new PD population a trial is underway to test the cell based therapy, which according to Dr. Roger Baker (lead investigator) professor of clinical neuroscience at Cambridge University in the United Knigdom is by any means designed to be a cure but rather another method by which dopamine is better (hopefully) delivered into the brain.
some of the previous trials problems were believed to be due to site implantation since the fetal nigral cells containing dopamine could not be directly placed into the hosts nigra, they were placed in the near by striatum. Uneven re-enervation of these cells is believed to be one of the causes of ‘runaway’ dyskenesias as well as the presence of serotonergic neurons from the donor raphe nucleus which can also produce dopamine in unregulated fashion. Further problem seen with initial procedure back in the 1980’s and 90’s is the yet unaccounted reason for the development of Lewy bodies in the grafted (donor) cells.
Because the European community ( where trials began) have always insisted on the merit of this procedure as a possible treatment a TRANSEURO consortium was gather to further discuss results. they have found there is a specific type of patient that responds best- so now they are recruiting patients between ages of 30-68 who have mild to moderate illness with minimal to no dyskenesias. now these patients will receive 3 fetal nigras on each side vs. the 2 used on each side in the past. these patients will receive a year worth of immunosuppression and be observed for 3 years ( believed to be time frame for maximal effect). they hope to control some of the emergence of dyskenesias by their new harvesting protocol which will decrease or minimize the number of serotonin containing neurons. hope is to improve dopamine related symptoms however, the non-dopaminergic effects will still remain unaffected.
Once again, I see hope ( but a smaller ray of sunshine than when I first began this trajectory) for a future generation of PD patients for a better life as I had once envision as a young neuroscientist. If this proves to be successful it will undoubtedly unleash a whole new era in the science of stem cell therapy research for the treatment of neurological diseases. However, I along with other more prominent neurologists like Dr. Anthony Lang caution those considering participating in such trial for it will be not a cure PD and if it works it will only provide limited results affecting only the symptoms related to dopamine. Keep in mind that a big part of the spectrum of PD is non-dopamine related and these are in fact the things which I believe as a doctor and patient which cause most PD persons problems such as gait instability, mood and sleep problem’s, along with declining cognition. so in the end, aside from boosting science in a new direction I don’t foresee this to replace DBS which has a long trajectory of excellent outcome and compared to fetal transplantation a much les invasive and aggressive surgery without the need for whole body immunosuppression which is known to carry many risks of its own accord. perhaps may have a niche for usage if works in those with young onset PD with Parkin gene mutation
Others of course like Dr. Baker are much more optimistic and believe that this may actually some day be first line therapy. highly doubt based on my years of experience with this disease and its complexities but one never knows….
Food for thought….
Robinson, R. (October 20, 2016); “Fifteen years later, a new trial set to test fetal transplants again is for Parkinson’s Disease.” Neurology Today. 16(20)13,23.