Bone marrow-derived mesenchymal stem cells, or MSCs, are a type of stem cell that can differentiate, or turn into other types of cells. They are taken from a patient’s own bone marrow. They have been used in several autoimmune diseases, including multiple sclerosis. MSCs can repair tissue and also inhibit the immune system, offering a potential treatment for neuromyelitis optica spectrum disorder (NMOSD). MSCs are given through an infusion.
Researchers recruited participants between September 2013 and January 2015. Participants were individuals with a diagnosis of NMO (based on criteria from 2006; diagnostic criteria were recently updated and can be found here), or with either recurrent optic neuritis or longitudinally extensive transverse myelitis and who were anti-AQP4 antibody positive. They were assessed at baseline, which was the day before treatment with MSCs, and 1, 3, 6, 9, and 12 months after treatment. The researchers looked at functional and structural outcomes. Functional outcomes were a scale (EDSS) that measures disability, a visual acuity test, and a cognitive test called the Paced Auditory Serial Addition Test (PASAT). Structural outcomes were MRIs of the optic nerve, brain, and spinal cord, and optical coherence tomography (OCT), which looks at the retina. They looked for relapses, which were new or recurrent neurological symptoms that lasted at least 24 hours. These symptoms were not counted if they were because of fever or infection. To be counted as a relapse, there had to be at least 30 days of separation from a previous episode. They also looked at the safety of the MSC treatment.
The study included 15 patients, with an average age of 47 years. Most (87%) participants were anti-AQP4 antibody positive. All of them had failed a different treatment prior to the study, meaning they had had at least one attack after receiving treatment. These prior treatments were cyclophosphamide or azathioprine, with or without steroids.
The MSC treatment did not cause side effects for most participants. Only one patient developed a low-grade fever and knee pain after the treatment, but these symptoms went away after treatment was completed. Weekly blood tests after the treatment were normal and no participants developed tumors within one year of treatment.
Twelve patients had no relapse at 12 months after MSC treatment, and three had at least one relapse. The relapses were mild. Their disability scores did not get worse and their symptoms went away after a month. The average annualized relapse rate was significantly lower after MSC treatment. Also, there were significantly fewer lesions in the optic nerve and spinal cord after treatment. The average disability score was also lower, and there was improvement in visual acuity and cognition. They had increased retinal nerve fiber layer thickness, optic nerve diameter, and upper cervical cord area. Three months after treatment, levels of anti-AQP4 antibodies decreased, but these levels went back to baseline again at 6-12 months. During the second year of the study, 13 participants were relapse free. Like the first year, the average annualized relapse rate was lower than before treatment and the average disability score was also lower than before treatment.
This small study did not have any obvious, serious, adverse events and supports an investment in larger controlled studies to understand the potential benefit of MSC treatment for NMOSD.