Scientific and ethical issues related to stem cell research and interventions in neurodegenerative disorders of the brain.

Should patients with Parkinson's disease participate in research involving stem cell treatments? Are induced pluripotent stem cells (iPSC) the ethical solution to the moral issues regarding embryonic stem cells? How can we adapt trial designs to best assess small numbers of patients in receipt of invasive experimental therapies? Over the last 20 years there has been a revolution in our ability to make stem cells from different sources and use them for therapeutic gain in disorders of the brain. These cells, which are defined by their capacity to proliferate indefinitely as well as differentiate into selective phenotypic cell types, are viewed as being especially attractive for studying disease processes and for grafting in patients with chronic incurable neurodegenerative disorders of the CNS such as Parkinson's disease (PD). In this review we briefly discuss and summarise where our understanding of stem cell biology has taken us relative to the clinic and patients, before dealing with some of the major ethical issues that work of this nature generates. This includes issues to do with the source of the cells, their ownership and exploitation along with questions about patient recruitment, consent and trial design when they translate to the clinic for therapeutic use.