FROM STEM CELLS TO MOTONEURONS
How
mammalian stem cells produce specific neuronal subtypes remains elusive. A recent
study shed light on the process by which motoneurons are generated from human
embryonic stem cells (Xue-Jun Li e coll., Specification
of motoneurons from human embryonic stem cells. Nature Biotechnology 23,
215-221, 2005).
Xue-Jun
Li and his colleagues found that retinoic acid action is required during
neuroectoderm induction for motoneuron specification and suggest that stem
cells have restricted capacity to generate region-specific projection neurons
even at an early developmental stage.