Iron-dependent vs. iron-independent cold-induced injury to cultured rat hepatocytes: a comparative study in physiological media and organ preservation solutions.

We previously described the entity of cold-induced apoptosis to rat hepatocytes and characterized its major, iron-dependent pathway. However, after cold incubation in some solutions, e.g. cell culture medium, hepatocytes show an additional, yet uncharacterized component of cold-induced injury. We here assessed the effects of organ preservation solutions on both components of cold-induced injury and tried to further characterize the iron-independent component. None of the preservation solutions (University of Wisconsin, histidine-tryptophan-ketoglutarate, Euro-Collins, histidine-lactobionate, sodium-lactobionate-sucrose and Celsior solutions) provided significant protection against cold-induced cell injury (LDH release after 24-h cold incubation/3h rewarming >65% for all solutions); three solutions even enhanced cold-induced injury. However, when the predominant iron-dependent mechanism was eliminated by the addition of iron chelators, all preservation solutions yielded hepatocyte protection that was clearly superior to the one obtainable in cell culture medium or Krebs-Henseleit buffer with iron chelators (LDH release after 24-h cold incubation/3h rewarming <or= 35% in all preservation solutions and 65+/-10% in culture medium). The iron-dependent and the weaker iron-independent component of cold-induced injury showed a different temperature dependence, and in experiments with modified Krebs-Henseleit buffer the principle of the preservation solutions that inhibits the iron-independent component was identified as the low chloride concentration of these solutions (LDH release after cold incubation/rewarming in the presence of iron chelators: 66+/-6% in regular and 22+/-8% in chloride-poor Krebs-Henseleit buffer). Taken together, these results suggest that solutions for cold storage of hepatocytes should be chloride-poor and contain an iron chelator.