For two people with a rare autoimmune disease, an experimental stem-cell transplant has kept symptoms away for more than 15 years.
The results, reported in Med, involve a man and a woman with severe neuromyelitis optica spectrum disorder, or NMOSD, a potentially fatal disease in which immune cells produce antibodies that attack the spinal cord and the nerve connecting the eye and the brain.
Symptoms can appear in episodes lasting days or months and include eye pain, vision loss, vomiting, and weakness or paralysis in the arms and legs. Current treatments can prevent those episodes with ongoing medication, but they did not work in these two people.
After the stem-cell transplant, the man’s neurological function improved. He resumed a normal life and went on to have two children. The woman was able to use her arms more effectively than before treatment and no longer requires medication to reduce symptoms.
“I don’t think we can say it’s a cure, but then again, it has addressed the problem the disease has caused over this very long period of time,” says Jiao Jiao Li, a biomedical engineer at the University of Technology Sydney in Australia.
The treatment, called allogeneic haematopoietic stem-cell transplant, uses donor stem cells collected from another person’s blood. The procedure has been used to treat some cancers, sickle-cell disease and other blood conditions.
Massimo Filippi, a co-author of the study and a neurologist at the IRCCS San Raffaele Hospital in Milan, Italy, and his colleagues say this is the first use of this therapy to treat NMOSD.
The man received the transplant in 2009 using stem cells from his sister. The woman received cells from an unrelated donor the following year. Both received a single infusion of donor stem cells.
“Being able to keep these people symptom-free for a long period of time is exciting,” says Bruce Milthorpe, a scientist at the University of Technology Sydney.
Before the transplant, both participants received the chemotherapy drugs fludarabine and treosulfan, along with a monoclonal antibody drug to remove the immune system’s B cells, which produce the antibodies that attack the spinal cord and optic nerve.
They also received a short course of antibodies and immunosuppressant drugs to prevent graft-versus-host disease, a common complication in which donor cells attack the recipient’s healthy cells. “The complication can be life-threatening,” Li says.
The study authors report that neither person developed antibodies associated with NMOSD, and both developed healthy immune systems.
Li says the procedure completely replaces the person’s immune system. She says other versions of the treatment that use a person’s own stem cells reset the immune system, but might not work as well in autoimmune conditions if the B cells producing the attacking antibodies are not totally eradicated.
Milthorpe says it is not clear if a stem-cell transplant would help every person with NMOSD because the study involved only two people. He says it can also be challenging to find suitable donors, but the study could be used as evidence to start a clinical trial.
Milthorpe also says the team’s method of obtaining stem cells directly from a donor’s blood is a positive development because it is less invasive than collecting stem cells from bone marrow.
The authors say both participants also developed negative outcomes, including swollen lymph nodes, an antibody deficiency that required treatment, and bladder cancer. They say secondary cancers are not uncommon after a stem-cell transplant, and the risks should be weighed against improvements in symptoms and quality of life.
The transplants also carry other risks. Infections that develop after treatment are the second most common cause of death associated with this therapy.
The team says the procedure should be reserved for young people who do not see improved symptoms from standard treatment or who have co-occurring autoimmune disorders.
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