Do amniotic fluid-derived stem cells differentiate into neurons in vitro?

Last year, De Coppi et al.1 reported that amniotic fluid–derived stem (AFS) cells can yield differentiated cells that express lineage-specific markers and acquire characteristic functions in vitro. In particular, in addition to other cell types, they assert that AFS cells can give rise in vitro to neurons. To support this, the authors provide data indicating that AFS cells exposed to a medium that has been previously shown to promote neuronal differentiation express typical neuronal markers. They also show that they can record a barium-sensitive potassium current from these cells and that the cells release glutamate. Given our specific competence and experience, we cannot comment on the characterization of nonneuronal types. We do think, however, that the presented data do not provide compelling evidence that AFS cells can specifically differentiate into neurons.