Challenges for taking primary and stem cells into clinical neurotransplantation trials for neurodegenerative disease.

We review the first generations of clinical trials of novel cell therapies applied to a range of neurodegenerative diseases in the context of mechanisms of functional efficacy. This in turn helps to determine the best strategies to be adopted and the potential chances for success in developing new cell therapies to clinical application in different conditions. We then consider the scientific, technical, ethical, regulatory and logistic issues to be resolved in translating effective laboratory cell-based protocols to patients in clinical trials. We draw optimistic conclusions about the likelihood of success in developing radical new approaches to a range of devastating, and currently untreatable, neurodegenerative conditions, but caution that the problems are complex and the solutions are likely to be slow and costly to achieve in order to overcome significant ethical and regulatory as well as scientific challenges.