Stem cell therapy for neurological disorders.

Neurological disease encompasses a diverse group of disorders of the central and peripheral nervous systems, which collectively are the leading cause of disease burden globally. The scope of treatment options for neurological disease is limited, and drug approval rates for improved treatments remain poor when compared with other therapeutic areas. Stem cell therapy provides hope for many patients, but should be tempered with the realisation that the scientific and medical communities are still to fully unravel the complexities of stem cell biology, and to provide satisfactory data that support the rational, evidence-based application of these cells from a therapeutic perspective. We provide an overview of the application of stem cells in neurological disease, starting with basic principles, and extending these to describe the clinical trial landscape and progress made over the last decade. Many forms of stem cell therapy exist, including the use of neural, haematopoietic and mesenchymal stem cells. Cell therapies derived from differentiated embryonic stem cells and induced pluripotent stem cells are also starting to feature prominently. Over 200 clinical studies applying various stem cell approaches to treat neurological disease have been registered to date (Clinicaltrials.gov), the majority of which are for multiple sclerosis, stroke and spinal cord injuries. In total, we identified 17 neurological indications in clinical stage development. Few studies have progressed into large, pivotal investigations with randomised clinical trial designs. Results from such studies will be essential for approval and application as mainstream treatments in the future.