FACTORS INFLUENCING SURVIVAL OF MAMMALIAN-CELLS EXPOSED TO HYPOTHERMIA .4. EFFECTS OF IRON CHELATION

Survival of V-79 Chinese hamster cells was assessed by colony growth assay after hypothermic exposure in the presence of iron chelators. At 5 °C, maximum protection from hypothermic damage was achieved with a 50 μM concentration of the intracellular ferric iron chelator Desferal. A 3-hr prehypothermic incubation with 50 μM Desferal followed by replacement with chelator-free medium at 5 °C also provided some protection. This was not observed when the extracellular chelator DETAPAC (50 μM) was used prior to cold storage. Treating 5 °C-stored cells with Desferal just prior to rewarming was ineffective, but treating cells with Desferal during hypothermia exposure after a significant period of unprotected cold exposure ultimately increased the surviving fraction. Submaximal protection during hypothermia was achieved to various degrees with extracellular chelators at 5 °C, including 50 μM DETAPAC and 110 μM EDTA. EGTA (110 μM) had little effect. The sensitization of cells at 5 °C with 200 μM FeCl3 could be reduced or eliminated with Desferal in accordance with a 1:1 binding ratio. At 10 °C, 50 μM Desferal, 50 μM DETAPAC, and 110 μM EDTA were as or less effective in protecting cells than at 5 °C. An Arrhenius plot of cell inactivation rates shows a break at 7-8 °C, corresponding to maximum survival for control cells and cells in 50 μM Desferal; however, the amount of protection offered by the chelator increases with decreasing temperature below about 19 °C, and sensitization increases above that point. It has not previously been shown that iron chelators protect against cellular hypothermia damage which is uncomplicated by previous or simultaneous ischemia. This may be relevant to the low-temperature storage of transplant organs, in which iron of intracellular origin and in the perfusate may be active and damaging. © 1990.