Advances in the use of stem cell transplants in the treatment of multiple sclerosis

Introduction

Since the first bone marrow transplant was performed in the 1950s, stem cell-based therapies have offered the potential to treat many chronic, degenerative conditions, and multiple sclerosis (MS) is no exception. Over the last decade, autologous haematopoietic stem cell transplantation (AHSCT), which aims to ‘reset’ the immune system, has been shown to have efficacy in reducing disease activity and disability progression in relapsing remitting (RRMS), leading to AHSCT becoming a viable therapeutic option for those with MS refractory to disease-modifying therapies (DMTs). This procedure however can be associated with significant morbidity, as it requires aggressive immunosuppression pre-transplantation. More recently, autologous mesenchymal stem cell transplantation (MSCT) has moved into the spotlight. MSCs are multi-potent, non-haematopoietic stromal cells, found mainly in the bone marrow. Pre-clinical trials have shown that they fulfil a potent immunomodulatory role and may have neurotrophic effects. Furthermore, in contrast to AHSCT, there is no requirement for pre-transplantation immunosuppression. However, the evidence of its efficacy in reducing MS disease progression has been limited. Three recently published phase II clinical trials investigating the effects of stem cell transplantation (AHSCT and MSCT) in MS are discussed below.