Background. Prolonged cold storage (CS) of donor kidneys is associated with tubular cell apoptosis and caspase-3 activation. We have previously shown that pancaspase inhibition prevents CS-associated tubular apoptosis. Because of the nonspecific nature of pancaspase inhibitors, which block all caspases including proinflammatory caspase-1, the effect of specific caspase-3 inhibition during CS is unknown. X-linked inhibitor of apoptosis (XIAP) is the most potent naturally occurring specific inhibitor of caspase-3. We hypothesized that prolonged CS would decrease XIAP, whereas upregulation of XIAP with the novel compound UCF-101 would protect against caspase-3 activation and tubular cell apoptosis. Methods. LLC-PK1 tubular cells and whole kidneys from C57BL/6 mice were subjected to prolonged CS with or without UCF-101, and examined for XIAP, caspase-3, and tubular apoptosis. Results. Tubular cells subjected to prolonged CS in vitro demonstrated significantly decreased XIAP and significantly increased apoptosis, caspase-3 protein and activity. UCF-101 treatment significantly increased XIAP, significantly decreased capsase-3 protein and activity, and protected against apoptosis. To determine the therapeutic significance, whole kidneys were subjected to prolonged CS with UCF-101. UCF-101 significantly increased XIAP in donor kidneys and protected against apoptosis.Conclusions. Prolonged CS of tubular cells in vitro and whole mouse kidneys ex vivo is associated with loss of XIAP and subsequent tubular cell apoptosis. UCF-101 protects against the loss of XIAP during prolonged CS both in vitro and ex vivo, and is associated with significantly reduced tubular cell apoptosis. UCF-101 may represent an attractive approach to improve organ preservation.
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