Abstract
Ultraprofound hypothermia (< 5°C) induces changes to cell membranes such as liquid‐to‐gel lipid transitions and oxidative stress that have a negative effect on membrane function and cell survival. We hypothesized that fatty acid substitution of endothelial cell lipids and alterations in their unsaturation would modify cell survival at 0°C, a temperature commonly used during storage and transportation of isolated cells or tissues and organs used in transplantation. Confluent bovine aortic endothelial cells were treated with 18‐carbon fatty acids (C18:0, C18:1n‐9, C18:2n‐6, or C18:3n‐3), C20:5n‐3 or C22:6n‐3 (DHA), and then stored at 0°C without fatty acid supplements. Storage of control cells caused the release of lactate dehydrogenase (LDH) and a threefold increase in lipid peroxidation (LPO) when compared to control cells not exposed to cold. Pre‐treating cells with C18:0 decreased the unsaturation of cell lipids and reduced LDH release at 0°C by 50%, but all mono‐ or poly‐unsaturated fatty acids increased injury in a concentration‐dependent manner and as the extent of fatty acid unsaturation increased. DHA‐treatment increased cell fatty acid unsaturation and caused maximal injury at 0°C, which was prevented by lipophilic antioxidants BHT or vitamin E, the iron chelator deferoxamine, and to a lesser extent by vitamin C. Furthermore, the cold‐induced increase in LPO was reduced by C18:0, vitamin E, or DFO but enhanced by DHA. In conclusion, the findings implicate iron catalyzed free radicals and LPO as a predominant mechanism of endothelial cell injury at 0°C, which may be reduced by increasing lipid saturation or treating cells with antioxidants. J. Cell. Biochem. 99: 784–796, 2006. © 2006 Wiley‐Liss, Inc.