The stem cell uncertainty principle

Stem cells are defined by capacities for both self-renewal and differentiation. Many different entities satisfy this working definition. Explicating the stem cell concept reveals it to be relational and relative, requiring contextualization by a cell lineage, organismal source, cell environments, and traits of interest. Not only are stem cell capacities relative to an experimental context; the stem cell concept imposes evidential constraints on the interpretation of experimental results. In consequence, claims about stem cell capacities are inherently uncertain. I discuss the implications of this result for progress in stem cell research and its public understanding