Blood stem cell transplantation is a radical but highly effective therapy for multiple sclerosis. A study led by the University of Zurich has now examined in detail the way in which the treatment curbs the autoimmune disease and how the immune system regenerates afterwards. A better understanding of these mechanisms should help the treatment approach, currently approved in only a few countries, to gain wider acceptance.
Every day, one person in Switzerland is diagnosed with multiple sclerosis. MS is an autoimmune disease in which the body’s own immune system attacks the myelin sheath of the nerve cells in the brain and spinal cord. The disease leads to paralysis, pain and permanent fatigue, among other symptoms. Fortunately, there have been great advances in therapies in recent decades. A study by the Department of Neuroimmunology and MS Research at the University of Zurich (UZH) and the Department of Medical Oncology and Haematology Clinic at the University Hospital Zurich (USZ) has now pinpointed why the most effective currently available therapy — a stem cell transplant — works so well.
Wiping out unwanted immune cells
“80 percent of patients remain disease-free long-term or even forever following an autologous hematopoietic stem cell transplant,” says recently retired Professor Roland Martin, study lead and last author. The treatment is particularly suitable for younger people with aggressive forms of the disease. Four years ago, thanks to the high effectiveness of the treatment and the now low mortality rate, Martin’s department together with the USZ clinic were granted approval to administer the therapy. It is the only clinic in Switzerland approved for this treatment.
During the treatment, several chemotherapies completely destroy the patients’ immune system — including the subset of T cells which mistakenly attack their own nervous system. The patients then receive a transplant of their own blood stem cells, which were harvested before the chemotherapy. The body uses these cells to build a completely new immune system without any autoreactive cells.
Systematic analysis of immune cells
“Previous studies have shown the basic workings of the method, but many important details and questions remained open,” says Martin. Some unclear aspects were what exactly happens after the immune cells are eliminated, whether any of them survive the chemotherapy, and whether the autoreactive cells really do not return.
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