Which patient groups should be asked to participate in first-in-human trials of stem-cell-based therapies?

The aims of this article are to consider (1) whether there are medical and societal differences among diseases regarding which patient groups should be asked to participate in first-in-human (FIH) trials of stem-cell-based therapies; (2) any differences in the light of values generally endorsed by different types of ethical theories, since the question in the title of this article is value laden, and its answer depends on which values one wants to promote and protect, and how they are ranked in importance; (3) whether the answer to that question is disease-specific, or whether it depends on factors common to several diseases. To illustrate these problems, we use Parkinson's disease (PD) and Huntington's disease (HD), between which there are important medical and societal differences. Moreover, research on stem-cell-based therapies for these diseases is being translated from research to practice. This approach to the problem can be applied to decision making about similar problems raised by other diseases that exhibit the same types of differences.