First-in-human cell transplant trials in Parkinson's disease: The need for an improved informed consent process.

First-in-human clinical trials of innovative medical procedures, such as cell transplantation for Parkinson's disease, present a variety of ethical challenges. In an era of rapidly developing stem cell technologies likely to be translated into clinical trials over the next few years, it is critical that ethical concerns be fully considered. One important undertaking is ensuring that research participants give free and truly informed consent. This will necessitate adequate disclosure of risks and benefits at a time when these are incompletely defined; ensuring understanding of a complex research protocol when there is significant possibility of therapeutic misconception; and careful determination of capacity for informed consent in patients with a neurodegenerative disorder that is known to affect cognition. Here we call attention to the ethical issues that researchers conducting these types of trials will face when trying to obtain a genuinely informed consent, and we suggest possible solutions.