Autologous stem cell transplantation for progressive multiple sclerosis: update of the European Group for Blood and Marrow Transplantation autoimmune diseases working party database

Emerging therapies for multiple sclerosis

This review examines the mode of action, safety profile and clinical efficacy of some of the most promising new therapeutic strategies for multiple sclerosis. Autologous hematopoietic stem cell transplantation can regenerate a new and tolerant immune system and is a potentially effective rescue therapy in a subset of patients with aggressive forms of MS refractory to approved immunomodulatory and immunosuppressive agents. High-dose cyclophosphamide without stem cell support is suggested to induce prolonged remissions through similar immunological mechanisms with less toxicity. Fingolimod (FTY720) is a novel oral immunomodulating agent that acts through preventing lymphocyte recirculation from lymphoid organs. Monoclonal antibody therapy has provided scientists and clinicians the opportunity to rationally direct the therapeutic intervention against specific molecules. Targeting molecules of the immune system such as CD52 (alemtuzumab), CD25 (daclizumab), VLA-4 (natalizumab) and CD20 (rituximab) have resulted in potent immunomodulatory effects through sometimes unpredicted mechanisms. The potential of immunoglobulins to induce remyelination in the CNS is being investigated in an attempt to develop therapies promoting tissue repair and functional recovery. The evidence supporting the potential of these emerging immunotherapies suggests that strong progress is being made in the development of effective cures for multiple sclerosis.

Human stem cells for CNS repair

Although most peripheral tissues have at least a limited ability for self-repair, the central nervous system (CNS) has long been known to be relatively resistant to regeneration. Small numbers of stem cells have been found in the adult brain but do not appear to be able to affect any significant recovery following disease or insult. In the last few decades, the idea of being able to repair the brain by introducing new cells to repair damaged areas has become an accepted potential treatment for neurodegenerative diseases. This review focuses on the suitability of various human stem cell sources for such treatments of both slowly progressing conditions, such as Parkinson's disease, Huntington's disease and multiple sclerosis, and acute insult, such as stroke and spinal cord injury. Despite stem cell transplantation having now moved a step closer to the clinic with the first trials of autologous mesenchymal stem cells, the effects shown are moderate and are not yet at the stage of development that can fulfil the hopes that have been placed on stem cells as a means to replace degenerating cells in the CNS. Success will depend on careful investigation in experimental models to enable us to understand not just the practicalities of stem cell use, but also the underlying biological principles.

Autologous mesenchymal bone marrow stem cells: practical considerations

A number of practical problems need to be addressed before any form of cell therapy can be widely applied in patients with multiple sclerosis. The choice of cell type is one considered elsewhere in this issue; others include the question of axon loss, that of continuing inflammatory disease activity, the mode of delivery of cells (bearing in mind the presence of innumerable lesions scattered throughout the CNS), the problem of measuring directly or indirectly the impact (if any) of an intervention, the timing of any treatment and perhaps above all the safety of the patient. All converge on the one increasingly relevant underlying question: when should stem cell treatments begin to be tested in patients? Here we review the progress in various of these practical problems in order to explain how we have arrived at the conclusion that the clinical science has progressed to a stage where the 'translation threshold' can be safely and appropriately crossed, and therefore why we have already commenced in Bristol a small pilot/feasibility study of autologous bone marrow cell treatment in patients with multiple sclerosis.

Haemopoietic stem cell transplantation--an evolving treatment for severe autoimmune and inflammatory diseases in rheumatology, neurology and gastroenterology

The concept of haemopoietic stem cell transplantation (HSCT) to treat severe autoimmune diseases has been around for several decades. Advances in the safety of HSCT have made it a clinical reality since 1995. Databases have registered around a thousand patients treated specifically for a wide range of diseases, predominantly multiple sclerosis (MS), systemic sclerosis (SSc), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Phase I/II prospective and retrospective studies have supported the potential of autologous HSCT as a treatment option in severely affected patients, with profound and prolonged clinical responses in some diseases, although procedures are generally not curative. Allogeneic HSCT appears to offer curative potential, but the potential of high toxicity has limited its use in this context. The exact role of HSCT remains to be defined, particularly in the context of other advances in the treatment of autoimmune disease. Along with other groups, the European Group for Blood and Marrow Transplantation (EBMT) are overseeing several phase III trials in autologous transplantation. Given the risks of the HSCT, eligibility is restricted to patients who have severe, treatment resistant disease, in whom the prognosis is otherwise poor. This review aims to summarise the current published data in this evolving treatment for relatively rare patients with resistant or rapidly progressive disease where treatment options are otherwise limited. This cross-fertilization of knowledge between many specialties may provide increasing therapeutic opportunities in otherwise untreatable diseases. Moreover, destroying and rebuilding immune systems may provide insights into autoimmune diseases.