Mesenchymal stem cells: new approaches for the treatment of neurological diseases.

Cellular therapies represent a new frontier in the treatment of neurological disease. Mesenchymal stem cells (MSCs), which can be harvested from bone marrow, adipose tissue, and umbilical cord blood, among many other sources, possess several qualities which may be used to treat diseases of the central nervous system. MSCs migrate to sites of malignancy, a property which may be used for the treatment of brain cancer. MSCs possess immunosuppressive properties, which may be used for the treatment of neurological disorders with an inflammatory etiology. Finally, MSCs restore injured neural tissue, a property which may be used for the treatment of neural injury. Approximately 23 clinical trials have been completed to date, with many more ongoing, and all have been listed in this review. The long-term safety of MSC-based therapies is not well established, and continues to be one major limitation to clinical translation. More broadly, only a small minority of clinical trials have employed rigorous designs that include prospective randomization, patients from multiple centers, clinically-relevant and reproducible endpoints, and adequate long-term follow-up. These limitations must be addressed before MSCs can enter widespread clinical use. Nevertheless, MSCs represent a promising new approach to treating diseases of the central nervous system that are traditionally associated with morbid outcomes. With additional pre-clinical and clinical studies that focus on their potential benefits as well as dangers, MSCs may one day find translation to clinical use in the setting of neurological disease.