Here we demonstrate that human neural stem cells (NSCs) proliferate while in space and they express specific NSC markers after being in space. NSCs displayed both higher oxygen consumption and glycolysis than ground controls. These cells also kept their ability to become young neurons. Electrophysiological recordings of space NSC-derived neurons showed immature cell membrane properties characterized by small capacitance and very high input resistance. Current injections elicited only an incipient action potential. No spontaneous synaptic events could be detected, suggesting their immature status even though most recorded cells displayed complex morphology and numerous cell processes. Ascertaining the origin of the NSCs' increased energy requirement is of the essence in order to design effective measures to minimize health risks associated with long-duration human spaceflight missions.
Keywords: energetics; glycolysis; microgravity; neural stem cells; neuronal specification; neurons; pluripotency; proliferation; space flight.