In vitro exposure of neural progenitor cell (NPC) populations to reduced O2 (e.g. 3% versus 20%) can increase their proliferation, survival and neuronal differentiation. Our objective was to determine if an acute (<1 hr), in vivo exposure to intermittent hypoxia (AIH) alters expansion and/or differentiation of subsequent in vitro cultures of NPC from the subventricular zone (SVZ). Neonatal C57BL/6 mice (postnatal day 4) were exposed to an AIH paradigm (20×1 minute; alternating 21% and 10% O2). Immediately after AIH, SVZ tissue was isolated and NPC populations were cultured and assayed either as neurospheres (NS) or as adherent monolayer cells (MASC). AIH markedly increased the capacity for expansion of cultured NS and MASC, and this was accompanied by increases in a proliferation maker (Ki67), MTT activity and hypoxia-inducible factor-1α (HIF-1α) signaling in NS cultures. Peptide blockade experiments confirmed that proteins downstream of HIF-1α are important for both proliferation and morphological changes associated with terminal differentiation in NS cultures. Finally, immunocytochemistry and Western blotting experiments demonstrated that AIH increased expression of the neuronal fate determination transcription factor Pax6 in SVZ tissue, and this was associated with increased neuronal differentiation in cultured NS and MASC. We conclude that in vivo AIH exposure can enhance the viability of subsequent in vitro SVZ-derived NPC cultures. AIH protocols may therefore provide a means to “prime” NPC prior to transplantation into the injured central nervous system.

In vitro exposure of neural progenitor cells (NPCs) to relative hypoxia (e.g. 3% versus 20% O2) can increase their proliferation, survival and neuronal differentiation both in culture and following transplantation. Recently, chronic intermittent hypoxia (CIH) was shown to increase proliferation in the dentate gyrus and subventricular zone (SVZ)—sites of postnatal neurogenesis. Our objective was to determine if in vivo exposure to acute intermittent hypoxia (AIH) could alter expansion and differentiation of subsequent in vitro cultures of SVZ NPCs. Neonatal C57BL/6 mice (postnatal day 4) were subjected to AIH (20×1 minute; alternating 21% and 10% O2), and sacrificed within 15 minutes of protocol termination. SVZ tissue was isolated and NPCs cultured as neurospheres (NS) or adherent monolayers (MASC). Expression of proliferation and neuronal fate markers was assessed with a range of methods including immunocytochemistry, western blot, fluorescence‐activated cell sorting and PCR. Our preliminary results indicate that in vivo exposure to AIH increases expression of proliferation and neuronal differentiation markers as subsequently assessed in in vitro NPC cultures. These data suggest that AIH protocols may provide a means to “prime” NPCs prior to harvest for subsequent transplantation into the injured central nervous system. This work is supported by 5K12HD055929 (HHR); 1R01HD052682‐01A1 (DDF)