Differential effects of in vivo vs. cell culture hypoxia on neural progenitor cell expansion and differentiation

Abstract

We have recently shown that neonatal in vivo exposure to acute intermittent hypoxia (AIH) increases proliferation and neuronal differentiation in subsequently cultured subventricular zone–derived neurospheres (NS). Prior work has also established that stem cells cultured in sustained hypoxia (SH, 3% vs. 20% O2) demonstrate increased proliferation and neuronal differentiation. The objective of this study was to compare and contrast NS behavior when exposed to either SH during culture or AIH delivered in vivo just prior to cell harvest. Neurosphere forming cells were isolated from neonatal C57BL/6 mice or Sprague Dawley rats. For SH, cells were maintained in 3% O2 for the duration of culture. For AIH, neonates were subjected to alternating cycles (20×2 minutes) of 21% and 10% O2. Expansion analysis demonstrated that SH‐treated NS initially outperformed control and AIH‐treated NS. However, after extended culture (7–10 days), SH‐treated NS exhibited reduced expansion when compared to both controls and AIH‐treated NS (the latter outperformed controls at all time points, p<0.05). Thus, compared to SH, in vivo AIH pre‐conditioning yields a more robust NS population following prolonged culture. We conclude that hypoxia is a powerful tool for manipulating NS growth, and that the pattern of delivery may have differential “priming” effects during long‐term culture. Support: 5K12HD055929 (HHR); 1R01NS080180 (DDF).