0288 In-vitro Model of the Microcirculation in OSA Based on Patient Profile

Introduction Microcirculatory endothelial dysfunction is a critical marker of subsequent cardiovascular disease in the population. We recently reported a profile of obstructive sleep apnea (OSA) specific gene changes in the human microcirculation. We sought to develop a precise in-vitro model of the microcirculatory effects of OSA using an intermittent hypoxia (IH) exposure that produces similar gene profile changes to that observed in patients with OSA. Methods We selected a cell line of immortalized human microvascular endothelial cells (HMEC). Then, we estimated the oxygen tension exposure of the peripheral circulation during OSA assuming a decrease from 120 mmHg in the pulmonary arteries to about 30 mmHg in the microcirculation. During a single episode of apnea, alveolar partial pressure of oxygen (PAO2) and the PaO2 at the level of the pulmonary arteries decrease slightly by about 10%. Therefore, we selected a fluctuation between 30-40 mmHg as baseline (normoxia), and 25-30mmHg to correspond with this decrease during apnea. We used a gas treatment 6-well cell culture chamber (model NOX-E.5-GTC, Noxygen) and monitored the O2 levels in the medium (cell level) and in the gas space with fluorescent oxygen analyzer (Oxylite, Optronix). We selected a 300 second cycle length and an exposure duration of 6-8 hours (72 cycles). Results Compared to HMECs in control normoxia, HMECs exposed to the IH protocol showed a profile change similar to that reported in humans with OSA with significant increase in oxidative and inflammatory genes. There was significant upregulation in NADPH subunit NOX4’s from 0.0439 to 0.1570 relative copy number (RCN), p= 0.049. Endothelin (EDN-1) expression increased from 1.0330 to 2.4171 p= 0.002. Superoxide dismutase (SOD-1) increased from 2.1336 to 2.4600 (p= 0.028). Interleukin 8 increased from 0.0891 to 0.2744 (p= 0.020). Interleukin 1-B increased from 0.0193 to 0.0439 (p= 0.048). Additional changes included a decrease in nitric oxide synthase . Conclusion The selected IH protocol produced similar gene profile changes in HMECs as those found in patients with OSA before treatment. This model can serve to evaluate the pathways specific to OSA's impact on the microcirculation and to test pharmacological therapies to target OSA-specific vascular disease. Support (if any) R 56 127079