Treating MS via stem cell therapy gains momentum
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Jeffrey Cohen, MD, is a neurologist with the Mellen Center for Multiple Sclerosis at Cleveland Clinic. He spoke with Healio about how stem cells are used to treat patients with multiple sclerosis. Cohen also discussed the potential that this line of research has for the one million Americans with MS.
What does current research suggest about stem cell therapy for MS?
One type of stem cell therapy for MS is hematopoietic stem cell transplant, also sometimes called a bone marrow transplant. In this approach, blood forming stems cells are mobilized from the bone marrow into the blood, harvested, and stored for later use. The patient then receives potent chemotherapy (the conditioning regimen) to rid the body of immune cells which cause inflammatory neurologic damage in MS. Then the stored stem cells are introduced to the body to shorten the aplastic phase and, in time, restore the immune system. Research suggests hematopoietic stem cell transplants have very potent, durable efficacy. In some patients, MS stays under control for 5-10 years without additional therapy, after they’ve received these transplants.
Hematopoietic stem cell transplant is fairly aggressive. There are a number of adverse events, primarily associated with conditioning regimen, including Clostridioides difficile diarrhea, dermatomal varicella zoster reactivations, upper respiratory tract infections and UTIs, that are tied to these transplants. But within 1 to 2 months after the transplant, most patients recover and do quite well.
In December, we began the BEAT-MS trial sponsored by the Immune Tolerance Network and National Institute of Allergy and Infectious Diseases that assesses a high-dose immunosuppression plus autologous hematopoietic stem cell transplantation against the best available disease modifying therapies for patients with highly active, treatment-resistant MS. In this trial, the conditioning regimen will be a 6-day regimen that consists of carmustine, etoposide, cytarabine and melphalan plus rabbit anti-thymocyte globulin.
How does stem cell therapy compare with other treatments for MS?
Though the hematopoietic stem cell transplant has the same purpose as disease modifying drugs for MS, previous research has suggested that the hematopoietic stem cell transplant is much more efficacious and has very durable efficacy.
Are there any emerging developments on the horizon regarding stem cell therapy?
One emerging development uses mesenchymal stem cells. That therapy isolates the mesenchymal stem cells from the bone marrow or adipose tissue (fat) and multiplied in the lab, and then reintroduced in greater numbers into their body. On occasion, the cells are sometimes treated prior to transfer to potentially enhance their ability to suppress nervous system-damaging immune responses and/or encourage myelin repair. This therapy has shown some promising results trials thus far.
Another development that is currently being tested in laboratories is one that would utilize embryonic stem cells and oligodendrocyte progenerator cells. These cells, which have the capacity to develop into myelin-forming oligodendrocytes, are isolated from embryos, thus involving significant practical and ethical issues. This approach looked very promising the laboratory but have not yet been tested in MS.
What additional research is needed on treating MS with stem cell therapy?
There are many unknowns surrounding mesenchymal stem cells therapy. We don't have a very good handle on how best to use those cells. We don't know the best place to isolate them from in the body. We don't know how to grow them in culture, we don't know the dose, i.e. how many to inject. We also don't know if the cells should be injected intravenously or through a spinal tap. Finally, it is not known for how long the new stem cells work.
There are a number of stem cell clinics out there offering mesenchymal stem cells on a fee for service basis. Though there has been a lot of research, and a lot of promise, it is premature to be using them on a routine basis at this point outside of research studies, in my view.
References:
- Burt RK, et al. JAMA. 2019;doi:10.1001/jama.2018.18743.
- Cleveland Clinic. New BEAT-MS trial stages direct comparison of stem cells and biologics for relapsing MS. Available at: https://consultqd.clevelandclinic.org/new-beat-ms-trial-stages-direct-comparison-of-stem-cells-and-biologics-for-relapsing-ms/. Accessed Feb. 7, 2020.
- National Multiple Sclerosis Society. Bone marrow stem cell transplant – HSCT. Available at: https://www.nationalmssociety.org/Research/Research-News-Progress/Stem-Cells-in-MS/Bone-Marrow-Stem-Cell-Transplant-%E2%80%93-HSCT. Accessed Feb. 7, 2020.
- National Multiple Sclerosis Society. Mesenchymal stem cells and iPSCs. Available at: https://www.nationalmssociety.org/Research/Research-News-Progress/Stem-Cells-in-MS/Mesenchymal-Stem-Cells. Accessed Feb. 7, 2020.
- National Multiple Sclerosis Society. Prevalence. Available at: https://www.nationalmssociety.org/About-the-Society/MS-Prevalence. Accessed Feb. 7, 2020.