Neuromyelitis Optica Spectrum Disorders (NMOSD)
Neuromyelitis optica spectrum disorder (NMOSD) is a chronic antibody-mediated demyelinating disorder.
Neuromyelitis optica spectrum disorder (NMOSD) is a chronic antibody-mediated demyelinating disorder, primarily affecting the optic nerves and the spinal cord. Recent discoveries have suggested that autoantibodies against the water channel protein aquaporin-4 (AQP4) mediated tissue damage is the mechanism underlying the development of NMOSD. The main symptoms include blindness, weakness or paralysis in the legs and arms, painful spasms, loss of sensation, uncontrollable vomiting and bladder or bowel dysfunction. Clinical attacks in NMOSD patients often evolve rapidly. If untreated, approximately 50% of NMOSD patients will be wheelchair users and blind, and a third will die within five years of their first attack. Early diagnosis and effective treatment are crucial to reduce disabilities and patient deaths. Fortunately, the prevalence of NMOSD is comparatively rare across the globe, lower than 50 cases per million.
There is no cure for NMOSD today. Available treatments are mainly aiming at reducing the inflammation of the CNS quickly and preventing progression and future relapses. The pharmacological agents normally consist of anti-inflammatory corticosteroids (e.g. methylprednisolone) and immunosuppression medicine (e.g., cyclophosphamide). Recently, several new Immunosuppressing drugs (e.g. eculizumab, inelizumab-cdon, and satralizumab) that target complement protein C5, CD19+ B cells, or IL-6 receptor have proven to be effective in treating anti-AQP4 antibody positive NMOSD patients. In some patients, plasma exchange therapy (PLEX) that directly removes AQP4-IgG antibodies from the circulation of the patient can also be used as an additional treatment.
Even though current NMOSD treatments are modestly effective, most of them can cause various adverse effects, such as infections, infusion related reactions, immunoglobulin depletion and low neutrophil counts, and liver enzyme abnormalities, which may limit their uses in some patients. Moreover, even after successful induction of remission, patients still contend with serious complications of spinal cord and optic nerve damage that limit their quality of life. There is a need for a better therapy that could both effectively control inflammation and repair neural damage.
Advances in Stem Cell Therapy for NMOSD Treatment
In regards to pluripotency and immune-modulatory function, mesenchymal stem cells (MSCs) hold the promise of a highly effective treatment for demyelination diseases. In 2016, the results from a two-year pilot trial evaluating safety and efficacy of bone marrow-derived MSCs in NMOSD patients were published (Fu Y et al., 2016), showing that MSC infusion reduces relapse frequency, mitigates neurological disability and repairs nerve damages over the two year observation period, supporting MSCs as a safe and effective treatment for patients with NMSOD. However, no clinical trial of MSCs in NMSOD has been registered within the United States.