Abstract 11040: Poloxamer 188 Protects Endothelial Cells From Hypoxia/Reoxygenation Injury - Implications for Cardio- and Neuroprotection After Cardiac Arrest

Abstract

Introduction: Cardiac arrest is a leading cause of death. Even with the best CPR, many patients die or suffer severe cardio-cerebral damage. Reintroduction of blood flow at the start of CPR after systemic ischemia may cause additional injury to organs such as the heart and brain beyond that caused by the ischemia itself. Determining the mechanism of action of a compound administered during CPR on the cellular dysfunction caused by ischemia/reperfusion could improve CPR practices in the future. Hypothesis: Poloxamer 188 (P188), with its unique hydro-/lipophilic chemical properties, protects coronary and cerebral endothelial cells against hypoxia/reoxygenation (H/R) injury. Methods: Endothelial cells (human coronary artery [HCAECs] and rat brain [RBECs]) underwent 2 hrs hypoxia (1% O2) then 2 hrs reoxygenation ± P188. Endpoints were markers of cellular injury (lactate dehydrogenase [LDH] release, mitochondrial dehydrogenase activity), proliferation, and nitric oxide (NO) release. Statistics: Student t-test followed by SNK post hoc comparisons, *p<0.05 vs control, † vs normoxia. Results: In HCAECs, H/R caused significant LDH release compared to cells in normoxic conditions (†0.774±0.084 vs 0.562±0.141 abs/mg protein; n=5). P188 significantly decreased LDH release in both hypoxic and normoxic conditions (*0.215±0.024 vs *0.273±0.02). P188 also significantly attenuated decreased mitochondrial dehydrogenase activity caused by H/R (*0.379±0.015 vs 0.468±0.035 abs/mg protein). NO measurement by DAF-2DA fluorescence showed higher levels in cells treated with P188 upon reoxygenation than controls (*164,944±6,716 vs 139,942±2,511 RFUs). In proliferation assays of HCAECs and RBECs, there was significantly lower proliferation following H/R than during normoxia (HCAECs: 16,030±716 vs †7,500±465; RBECs: 13,563±1,251 vs †7,323±297 cells/well). This decrease was dose-dependently attenuated by P188 when compared to control (HCAECs: 1μM, *8,523±495; 1mM, *8,827±375. RBECs: 1μM, *7,782±274; 1mM, *8,930±177). Conclusions: HCAECs and RBECs were protected by P188 against H/R, and P188 also increased NO release in HCAECs. P188 protection of cardiomyocytes and neurons may be mediated by the preservation of NO release from the endothelium.