Methods of preventing and/or treating ischemia, organ dysfunction and/or organ failure, including multiple organ dysfunction syndrome (MODS), and necrosis and apoptosis associated with organ dysfunction/failure, are provided. For instance, the methods involve contacting organ(s) with an oxygenated cholesterol sulfate (OCS), e.g. 5-cholesten-3,25-diol, 3-sulfate (25H-C3S). The organ(s) may be in vivo (e.g. in a patient that is treated with the OCS) or ex vivo (e.g. an organ that has been harvested from a donor and is to be transplanted).