Clinical application of adult stem cell therapy in neurological disorders

Recent advance in the knowledge of stem cell biology and early success in preclinical studies have prompted scientists to design clinical trials for neurodegenerative disorders including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), and Parkinson's disease (PD). Instead of a cell replacement strategy aiming at unidirectional neuroregeneration, neuroprotective or immune-inflammatory modulations by autologous or allogeneic cell transplantation are becoming central themes in clinical trials. Although stem-cell therapy for intractable neurological disorders is an attractive strategy, numerous essential issues targeting not only safety, efficacy, and source controls, but also clinical protocols, and ethical, regulatory, societal, and cost-benefit effectiveness for stem-cell therapy should be addressed for successful clinical application. Recent promising animal and early clinical data for neurodegenerative disorders might overestimate the hope of stem cell therapy; however, hype is still present for clinical practice. For the successful application of novel stem cell therapy, it is necessary to follow each nation's FDA regulations and international guidelines for the clinical translation of stem cells.