Abstract: Neural stem cells residing in the adult human brain have the potential to provide a source of tissue for self-to-self cell replacement strategies for the treatment of neurodegenerative diseases. Adult human neural stem cells (NSCs) are self renewable in culture and can generate mature neural progeny which display the characteristics of functional neurons and glia. Despite this, a number of concerns remain regarding their current suitability for treating neurodegenerative disorders. It must be demonstrated that desired neuronal types can be generated in clinically significant quantities, and can induce long-lasting functional improvements in well-characterised animal models of neurodegenerative disorders. Furthermore, the risks to patients in terms of tumour formation and side effects must be adequately assessed. Due to the paucity of data on adult human NSCs, a move from preclinical studies to clinical trials in human patients in the foreseeable future is unlikely. If clinical trials with autologous NSCs are pursued as a treatment option for neurodegenerative diseases, then lessons and insights from many years of clinical trials with fetal neural transplantation for Parkinson's and Huntington's diseases will be invaluable, and should be heeded. Issues include experimental versus therapeutic research, standardisation of methodologies, and minimisation of risks and maximisation of benefits.
