OBJECTIVETo study the effect of hyperbaric oxygen (HBO) administered at different pressures and different exposure time on the differentiation of neural stem cells (NSCs) in vitro.

METHODSThe cerebral cortices from newborn rats (0-3 days old) were sterilely collected, digested, and centrifuged. After removal of the supernatant, the cells were re-suspended with DMEM/F12 medium containing B27, bFGF and EGF. The NSCs of 2-3 passages were randomly divided into seven groups: a control (untreated) and 6 HBO treatment groups that NSCs were subjected to HBO treatment of different pressures (1, 2 or 3 ATA) and different exposure time (30 or 60 minutes). The differentiated NSCs were examined by neuron-specific enolase (NSE) immunocytochemistry 24 hrs later. Percentage of NSE positive cells differentiated from NSCs was assessed by fluorescent microscopy.

RESULTSThe percentage of NSE positive cells differentiated from NSCs was the highest in the HBO 2ATA-60 min group (9.17+/-0.50%) (P<0.01), followed by the HBO 3ATA-60 min (7.89+/-0.62%), HBO 2ATA-30 min (6.72+/-0.76%), HBO 3ATA-30 min (6.08+/-0.57%), HBO 1ATA-60 min (5.45+/-0.52%), HBO 1ATA 30 min (3.85+/-0.44%) and control groups (3.72+/-0.88%). In addition to the HBO 1ATA-30 min group, the other HBO treatment groups had increased significantly percentage of NSE positive cells compared with the control group (P<0.01). Under the same pressure, the 60 min treatment groups had increased significantly percentage of NSE positive cells compared with the 30 min treatment groups (P<0.01).

CONCLUSIONSHBO treatment (2 ATA, 60 minutes) produces a best effect in the differentiation of NSCs into neurons.