Endothelial Dysfunction in a Cell Culture Model Exposed to Various Intermittent Hypoxia Modes.

Wang, Juan, Jiahui Wang, Xin Li, Wanju Hou, Jie Cao, and Jing Feng. Endothelial dysfunction in a cell culture model exposed to various intermittent hypoxia modes. High Alt Med Biol. 21:388-395, 2020. Objective: To construct an in vitro model of endothelial cells exposed to various intermittent hypoxia (IH) modes, and determine whether different frequencies and degrees can cause different effects on endothelial cells. Methods: EA.hy926 cells were used to set up the cell model. A program-controlled gas delivery system was designed to regulate the flow of premixed air into the cell culture chamber. The cells were divided into eight groups exposed to various IH modes: standard cell culture group, intermittent normoxia (IN) group (21% O2 15 seconds/21% O2 3 minutes 45 seconds for 12 cycles/h), IH1 group (1.5% O2 15 seconds/21% O2 8 minutes 15 seconds for 6.32 cycles/h), IH2 group (1.5% O2 15 seconds/21% O2 5 minutes 15 seconds for 9.23 cycles/h), IH3 group (1.5% O2 15 seconds/21% O2 3 minutes 45 seconds for 12 cycles/h), IH4 group (1.5% O2 15 seconds/21% O2 1 minute 45 seconds for 20 cycles/h), IH5 group (1.5% O2 15 seconds/21% O2 15 seconds for 40 cycles/h), and IH6 group (10% O2 15 seconds/21% O2 3 minutes 45 seconds for 12 cycles/h). Results: Nuclear factor κB (NFκB) p65, c-fos, tumor necrosis factor-alpha (TNFα), malondialdehyde (MDA), and endothelin-1 (ET-1) were higher in the IH3 group or IH6 group than those in IN group, and they were much higher in IH3 group than those in IH6 group. Superoxide dismutase (SOD) and nitric oxide (NO) were the opposite results. In IH1, IH2, IH3, IH4, and IH5 groups, the frequencies increased gradually. NFκB p65, TNFα, and c-fos were the highest in IH3 group. MDA and ET-1 were the highest in IH2 group. SOD and NO were the lowest in IH2 group. Conclusions: Different IH frequencies and degrees could cause different effects on endothelial cells. The endothelial responses varied with the duration of reoxygenation. So, the duration of reoxygenation was the key phase for endothelial dysfunction.