Overcoming severe renal ischemia: The role of ex vivo warm perfusion

Background. The ability to effectively utilize kidneys damaged by severe (2 hr) warm ischemia (WI) could provide increased numbers of kidneys for transplantation. The present study was designed to examine the effect of restoring renal metabolism after severe WI insult during ex vivo warm perfusion using an acellular technology. After warm perfusion for 18 hr, kidneys were reimplanted and evaluated for graft function. Methods. Using a canine autotransplant model, kidneys were exposed to 120 min of WI. They were then either reimplanted immediately, hypothermically machine perfused (4degreesC) for 18 hr with Belzer's solution, or transitioned to 18 hr of warm perfusion (32degreesC) with an acellular perfusate before implantation. Results. Warm perfused kidneys with 120 min of WI provided life-sustaining function after transplantation, whereas the control kidneys immediately reimplanted or with hypothermic machine perfusion did not. The mean peak serum creatinine in the warm perfused kidneys was 3.7 mg/dl, with the mean peak occurring on day 2 and normalizing on day 9 posttransplant. Conclusions. These results indicate that 18 hr of ex vivo warm perfusion of kidneys is feasible. Furthermore, recovery of renal function during warm perfusion is demonstrated, resulting in immediate function after transplantation. The use of ex vivo warm perfusion to recover function in severe ischemically damaged kidneys could provide the basis for increasing the number of transplantable kidneys.