Understanding Stem Cell Therapy in Parkinson’s Disease Treatment

On April 29, 2018, the Washington Post published an article examining commercial stem cell clinics in the United States that market non-FDA approved treatments directly to the public for a variety of health issues, including arthritis, macular degeneration and of particular note to us, Parkinson’s disease (PD).

How commercial stem cell clinics work

A typical treatment at one of these clinics involves removing fat cells from the abdomen (some clinics remove bone marrow or blood for this procedure), treating the cells in various ways in order to isolate mesenchymal stem cells or stromal cells from the removed tissue, and finally injecting these cells back into the body. The cells are re-introduced into the body in different locations (into the bloodstream, cerebral spinal fluid, nose, eye, etc.) depending on which disease is being targeted. Such treatments are performed for a fee, sometimes a large one, and are not covered by insurance.

Pictured: Dopamine neurons derived from iPSCs from the lab of Xiaobo Mao, PhD

Does it work? Efficacy of commercial stem cell clinics

Commercial clinics do not as a rule publish their results in peer-reviewed journals to demonstrate to the scientific community that the treatments work. Rather, they usually rely on anecdotes from patients as proof of efficacy. Some clinics are tracking their results by measuring variables such as quality of life before or after the procedure. However, without comparing the patients to a similar group who does not receive the treatment, it is hard to know whether any improvement is due to placebo effect or to the treatment itself.

Is it safe? Safety of commercial stem cell clinic work

Safety data is also limited, although there have been some publicized lawsuits claiming that these treatments resulted in harm. Stem cell researchers in general question whether cells harvested in such a way contain sufficient amounts of adult-derived stem cells to be meaningful. It is also unclear how this type of procedure would target the stem cells to the correct location. If stem cells are introduced in the nose for example, it is unclear how they would find their way to the basal ganglia and make the correct connection in order to help a person with Parkinson’s disease.

In order for the medical community to accept this type of treatment as safe and beneficial, it would need to be shown to work in a placebo-controlled clinical trial for which participants do not pay, are aware of the known risks and benefits, and are carefully monitored throughout the trial. In addition, the trial would need to track adverse events, as well as record and share the outcomes of trial participants as they compare to the group of patients receiving a placebo treatment. So far this has not happened. The FDA is in fact studying mesenchymal stem cells in the laboratory in order to determine the best way to use them to help people, but these studies have not yet led to approved treatments. Most recently, the FDA filed federal complaints against two clinics that are marketing stem cell products without regulatory approval.

Are there stem cell therapies for Parkinson’s?

Researchers are working on it. Stem cells, often derived from a patient with Parkinson’s disease, are currently being studied extensively in the laboratory, both to further our understanding of the molecular mechanisms that cause cell death in PD, and also as a test environment for new medications. However, there are currently no stem cell treatments for Parkinson’s disease that have been developed and tested to the point that we are sure that they help and do not cause harm. Researchers however, are furiously underway to develop such a treatment. The research is focused on deciphering the best source of stem cells to use, the best ways to turn the stem cells into dopaminergic neurons (the type of neurons that are depleted in Parkinson’s disease) and the best ways to introduce the cells into the brain for maximal effect and minimal harm.

Stem cell types are:

1. Embryonic stem cells (ESCs)– Stem cells derived from a human embryo, typically at a very early developmental stage. Early embryos created by in vitro fertilization (IVF) and are not going to be used, are typically the source of these cells. (This is as opposed to fetal stem cells which are typically derived from an older embryo.)
2. Adult derived stem cells (also called tissue-specific stem cells) – Stem cells found among, and then isolated from, differentiated cells in an adult. The most well understood of these are hematopoietic stem cells found in adult blood and bone marrow, which have been used clinically for decades, mostly to treat blood cancers and other disorders of the blood and immune systems.
3. Umbilical cord stem cells – Hematopoietic stem cells are also found in umbilical cord blood retrieved after delivery. These too are used clinically to treat blood cancers and some rare genetic disorders
4. Mesenchymal stem cells also known as stromal cells are present in many tissues such as bone, cartilage and fat. They remain poorly understood, but likely have regenerative potential. These are the cells that are harvested at the commercial stem cell clinics described above.
5. Induced pluripotent stem cells (iPSCs) – Stem cells created from adult skin or blood cells that have been reprogrammed to revert to an embryonic state.
6. Human parthenogenetic stem cells – Stem cells created from an unfertilized human ovum.

The future of stem cell therapy for Parkinson’s

Four groups dedicated to using stem cell therapies to treat Parkinson’s disease have formed an international consortium known as G Force PD. Each of the four centers is planning a clinical trial to start in the next 1-4 years. They differ on the source of stem cells that they will be using (ESCs vs iPSCs). All will be injecting the cells directly into the basal ganglia part of the brain where the ends of the dopamine producing neurons live. The Parkinson’s community eagerly awaits the implementation of these trials.

When open for enrollment, should I consider participating in a stem cell trial?
When faced with an illness like PD, you can at times feel that it is worthwhile to try anything that may lead to a cure. It’s important to always make sure however, that you’re dealing with trusted information, proven therapies, and clinical trials that have been properly vetted by the medical community.

What if you want to get involved? Participation in a clinical trial that is investigating the use of stem cell treatments for Parkinson’s disease will allow you to be involved in bringing such treatments to fruition. It is incredibly important to note however, that clinical trials that are entered on clinicaltrials.gov, the NIH-managed directory of all clinical trials, are not vetted by the NIH, and commercial stem cell clinics we mentioned earlier can put their treatments on this site to recruit patients. Most people don’t realize this, which led clinicaltrials.gov to put a new disclaimer on their site stating: “The safety and scientific validity of this study is the responsibility of the study sponsor and investigators.”

Therefore, in order to use clinicaltrials.gov safely, focus on the trials conducted at academic medical centers in the United States. Once you have identified a trial that you might be interested in, talk it over with your doctor before committing to anything.

Be aware that a clinical trial utilizing stem cells will likely require the cells to be injected directly into the brain, which will inevitably be associated with a certain amount of risk. You will need to discuss details of this risk with your doctor and the trial organizers.

Does APDA fund any stem cell research?
APDA is committed to funding research to further our understanding of PD and to bring new treatments to patients as quickly as possible. Recent funding of Dr. Xiabo Mao, at Johns Hopkins University School of Medicine in Baltimore, MD, allowed him to use iPSCs to model PD and test a potential new avenue of treatment.

Tips & Take-aways:

• Be cautious of any clinic promoting a treatment that has not been proven by the FDA to be safe and effective.
• There is some promise in the area of using stem cells as a possible treatment for PD, but much more research needs to be done before such a therapy will be approved for clinical use.

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