Viral Hyperinfection of the Central Nervous System and High Mortality After Hematopoietic Stem Cell Transplantation for Treatment of Theiler’s Murine Encephalomyelitis Virus-Induced Demyelinating Disease

Autologous haematopoietic stem cell transplantation for neurological diseases

Neuroinflammatory diseases such as multiple sclerosis, neuromyelitis optica, chronic inflammatory demyelinating polyneuropathy and myasthenia gravis are leading causes of physical disability in people of working age. In the last decades significant therapeutic advances have been made that can ameliorate the disease course. Nevertheless, many affected will continue to deteriorate despite treatment, and the costs associated with disease-modifying drugs constitute a significant fiscal burden on healthcare in developed countries. Autologous haematopoietic stem cell transplantation is a treatment approach that aims to ameliorate and to terminate disease activity. The erroneous immune system is eradicated using cytotoxic drugs, and with the aid of haematopoietic stem cells a new immune system is rebuilt. As of today, more than 1000 patients with multiple sclerosis have been treated with this procedure. Available data suggest that autologous haematopoietic stem cell transplantation is superior to conventional treatment in terms of efficacy with an acceptable safety profile. A smaller number of patients with other neuroinflammatory conditions have been treated with promising results. Herein, current data on clinical effect and safety of autologous haematopoietic stem cell transplantation for neurological disease are reviewed.

Neuropathogenesis of Theiler's murine encephalomyelitis virus infection, an animal model for multiple sclerosis

Theiler's murine encephalomyelitis virus (TMEV) infection of mice is an experimental model for multiple sclerosis (MS). TMEV induces a biphasic disease in susceptible mouse strains. During the acute phase, 1 week after infection, TMEV causes polioencephalomyelitis characterized by infection and apoptosis of neurons in the gray matter of the brain. During the chronic phase, about 1 month after infection, virus infects glial cells and macrophages, and induces inflammatory demyelination with oligodendrocyte apoptosis and axonal degeneration in the white matter of the spinal cord. Although antibody, CD4(+), and CD8(+) T cell responses against TMEV capsid proteins play important roles in neuropathogenesis, infectious virus with persistence is necessary to induce demyelination; in general, adoptive transfer of antibody or T cells alone did not induce central nervous system (CNS) disease. The TMEV model can be useful for testing new therapeutic strategies specifically as a viral model for MS. Therapies targeting adhesion molecules, axonal degeneration, and immunosuppression can be beneficial for pure autoimmune CNS demyelinating diseases, such as experimental autoimmune encephalomyelitis, but could be detrimental in virus-induced demyelinating diseases, such as progressive multifocal leukoencephalopathy.

Induction of tolerance in autoimmune diseases by hematopoietic stem cell transplantation: getting closer to a cure?

Hematopoietic stem cells (HSCs) are the earliest cells of the immune system, giving rise to B and T lymphocytes, monocytes, tissue macrophages, and dendritic cells. In animal models, adoptive transfer of HSCs, depending on circumstances, may cause, prevent, or cure autoimmune diseases. Clinical trials have reported early remission of otherwise refractory autoimmune disorders after either autologous or allogeneic hematopoietic stem cell transplantation (HSCT). By percentage of transplantations performed, autoimmune diseases are the most rapidly expanding indication for stem cell transplantation. Although numerous editorials or commentaries have been previously published, no prior review has focused on the immunology of transplantation tolerance or development of phase 3 autoimmune HSCT trials. Results from current trials suggest that mobilization of HSCs, conditioning regimen, eligibility and exclusion criteria, toxicity, outcome, source of stem cells, and posttransplantation follow-up need to be disease specific. HSCT-induced remission of an autoimmune disease allows for a prospective analysis of events involved in immune tolerance not available in cross-sectional studies.

Stem cell transplantation in multiple sclerosis: multiple choices and multiple challenges

Multiple sclerosis (MS) is generally considered as an autoimmune disease of the central nervous system. This concept has led to the idea that profound immunosuppression followed by transplantation of stem cell grafts would stop, or at least slow down, disease activity. Supported by the positive effects of hematopoietic stem cell transplantation (HSCT) on experimental autoimmune encephalomyelitis and by anecdotal reports on the beneficial effect of HSCT on MS patients with concomitant malignant disease, HSCT programs for MS have been initiated worldwide. At this stage, it is impossible to draw general conclusions from the preliminary data reported and therefore overenthusiastic expectations should be tempered. The follow-up periods are too short the groups are too small, the selected patients and protocols too heterogeneous, and publication bias on positive results cannot be excluded. However, there is ample evidence that HSCT is a technically feasible approach in MS, not more dangerous than in the hemato-oncological diseases. For every step in the HSCT procedure, there are many different options. The time has come for a systematic analysis of the safety and efficacy associated with the different methodologies.

Engraftment syndrome: a common cause for rash and fever following autologous hematopoietic stem cell transplantation for multiple sclerosis

Autologous hematopoietic stem cell transplantation (HSCT) is currently being evaluated as a therapy for patients with progressive multiple sclerosis (MS) at risk of debilitating neurological impairment. While preliminary results from a few studies have been reported, little is known about toxicities or outcome of HSCT for MS. We report a relatively frequent triad of non-infectious fever, rash and fatigue or lassitude that may also be associated with pruritus, pulmonary symptoms, and eosinophilia and frequently occurs around engraftment. This syndrome occurred in 26% of our series of patients (5/19) undergoing HSCT for multiple sclerosis. The engraftment syndrome is usually self-limited but may require intervention with systemic corticosteroids.