Hyperthermia preconditioning induces renal heat shock protein expression, improves cold ischemia tolerance, kidney graft function and survival in rats.

Background: Evidence indicates that hyperthermia preconditioning (HP) can be protective in kidney transplantation, possibly through increased heat shock protein (HSP) expression. A detailed study about individual HSPs and functional preservation is lacking, however. Therefore, we studied the effects of HP on kidney graft survival, function and HSP expression.

Methods: Male Lewis rats were or were not subjected to whole-body hyperthermia 24 h prior to kidney procurement. Kidneys were stored in UW solution at 4 degrees C for 32, 40 or 45 h. Recipient kidneys were both removed and single isografts transplanted orthotopically.

Results: HP strongly induced HSP72 and HSP32 expression. Following 32-hour cold ischemia, most animals survived even without prior HP. However, HP strongly reduced functional impairment induced by cold ischemia. Following 40-hour cold ischemia, kidneys from donors without HP did not recover function and all animals died within 3 days. In contrast, HP-exposed kidneys tolerated 40-hour storage significantly better, with 44% of rats surviving until sacrifice on day 7. In these animals, renal function was still better compared to animals with 32-hour-stored kidneys without HP. Histological alterations were also diminished following HP.

Conclusion: Our data show that HP induces renal HSP72 and, for the first time, HSP32. HP increases survival following transplantation and acts by improving several parameters of kidney function including proteinuria, volume output and creatinine clearance.