FIGURE 4.

Experimental setting based on gas diffusion through a thin gas permeable membrane. (A) Schematic view of a cell culture well based on a gas permeable membrane. Gas partial pressure applied to the cells cultured on one side of the membrane is virtually the same as in the gas circulating through the other side of the membrane. (B) Example of intermittent hypoxia (IH) patterns actually measured on top of the membrane (cell culture level) when applying IH with different magnitudes [20–1% O₂ (blue line) and 13–4% O₂ (black line) at a frequency of 60 cycles/h]. (C) Real image of a setting containing six wells. (D) Human aortic endothelial cells wound closure index under IH. Both frequency and amplitude range of IH induced significant changes in wound healing. Low-frequency IH (0.6 cycles/h) accelerated endothelial wound healing in the 4–13% magnitude range, while high-frequency IH patterns simulating severe OSA (60 cycles/h) did not significantly modify wound closure rates regardless of oxygen levels. Data were normalized to the condition of continuous 13% O₂. n = 6 each group. ^∗P < 0.05; ^∗∗∗P < 0.001. (A) and (C) reproduced from Campillo et al. (2017a) (http://creativecommons.org/licenses/by/4.0/). (B) and (D) reproduced from Campillo et al. (2017b) with permission from the copyright owner.