Derivation of neural precursor cells from human ES cells at 3% O 2 is efficient, enhances survival and presents no barrier to regional specification and functional differentiation

In vitro stem cell systems traditionally employ oxygen levels that are far removed from the in vivo situation. This study investigates whether an ambient environment containing a physiological oxygen level of 3% (normoxia) enables the generation of neural precursor cells (NPCs) from human embryonic stem cells (hESCs) and whether the resultant NPCs can undergo regional specification and functional maturation. We report robust and efficient neural conversion at 3% O 2, demonstration of tri-lineage potential of resultant NPCs and the subsequent electrophysiological maturation of neurons. We also show that NPCs derived under 3% O 2 can be differentiated long term in the absence of neurotrophins and can be readily specified into both spinal motor neurons and midbrain dopaminergic neurons. Finally, modelling the oxygen stress that occurs during transplantation, we demonstrate that in vitro transfer of NPCs from a 20 to 3% O 2 environment results in significant cell death, while maintenance in 3% O 2 is protective. Together these findings support 3% O 2 as a physiologically relevant system to study stem cell-derived neuronal differentiation and function as well as to model neuronal injury.