This is an interesting short interview with a researcher working on aspects of a stem cell therapy for Parkinson's disease, with unusual results from animal studies in that the transplanted cells survive for a long time. In most first generation stem cell therapies, the cells produce benefits through signaling and do not live long or integrate with patient tissues in any significant numbers. Parkinson's is characterized by the loss of a small but vital population of neurons in the brain, something that happens in the course of normal aging as well, but not to the same degree. Thus for quite some time researchers have been aiming at replacement of these cells as a therapy:
Dr. Xianmin Zeng at The Buck Institute for Research on Aging focuses on potential treatments and therapies for Parkinson's disease. After years of dedicated work creating cell lines and collaborating on a delivery system the Zeng laboratory and their industry collaborators have developed a stem cell based treatment that is ready for human clinical trials. The treatment relies on a specialized process to make and purify nerve cells from induced pluripotent stem cells (iPSCs) which can be implanted into humans. In the process of creating the iPSCs multiple patient lines were also created resulting in an invaluable resource of a wide variety of Parkinson's patient lines. Having this vast variety of patient lines allows researchers to better understand the different mutations that can cause Parkinson's disease.
"Although the best-case scenario is having your own cells modified and implanted back into you, this is a therapy for only one person. An allogeneic donor line after being tested and verified can serve multiple patients. It is a bit like having a blood bank; one line of allogeneic cells will work for many patients, while another line of allogeneic cells will work for a different set of patients. The challenge is to calculate how many different allogeneic lines are needed to work with 90% of the patient population."
Another challenge with Parkinson's disease lies in delivering the desired treatment to the brain. These cells are able to populate the diseased area, differentiating into the appropriate cell type and replacing the dead neurons. One way in which this widespread delivery might be accomplished is to have a single injection that can be multi-pronged, reaching many areas of the brain. If this treatment works it could have a broad impact by serving as as a template to treat a variety of other neurodegenerative diseases. "It is not expected that you would need to do this treatment repeatedly. In the animal studies that we conducted the transplanted cells survived over six months. If one were to extrapolate this to human lifespan then it could be many years in which the cells will both survive and integrate into the brain after treatment."