LAUSR

Intradialytic hypoxemia is associated with oxidative stress, endothelial dysfunction, inflammation, higher erythropoietin requirements, and higher all-cause hospitalization and mortality in hemodialysis (HD) patients (Meyring-Wosten, et al., 2016). The aim of the present study was to further expand our insights into the hypoxia-uremia axis by investigating the oxidative balance in endothelial cells (EC) under hypoxic and uremic conditions. Human umbilical EC were incubated with DMEM medium supplemented with 10% of fetal bovine serum (FBS; control) or with sera obtained from healthy subjects (S-CON) or HD patients (S-HD, 1:10), respectively, for 40 minutes, 4 hours, and 24 hours under normoxic (21% O2) or hypoxic (5% O2) conditions (Culture Chamber ProOx, Biospherix). EC were analyzed by flow cytometer (BD Accuri™ C6 Plus) to assess a) intracellular production of reactive oxygen species (ROS, DCFH-DA probe, Abcam); b) reduced glutathione (GSH) content (ThiolTracker Violet probe, Thermo Fisher Scientific). S-HD increased intracellular ROS production at all time points compared to S-CON. Moreover, ROS production was higher under hypoxic conditions. ROS production declined after 24 hours. S-HD induced slightly higher GSH content when compared to S-CON in normoxia (Table 1). In our in vitro experiments, hypoxia and uremia jointly favor EC oxidative imbalance. This effect is particularly pronounced after 4 hours. Translational studies are warranted to explore the clinical relevance of our findings.