Transplanted kidneys usually experience several episodes of ischemia, including cold ischemia during allograft storage in preservation solution. However, previous studies focusing on cold renal ischemia were only carried out in vitro or ex vivo. In the present study, we developed and characterized an in vivo mouse model of renal ischemia-reperfusion injury (IRI) induced exclusively by cold ischemia. C57BL/6 mice underwent right kidney nephrectomy, and the left kidney was kept cool with circulating cold saline in a kidney cup, while body temperature was maintained at 37°C. We clamped the renal pedicle and flushed out the blood inside the kidney with cold saline via an opening on the renal vein. The severity of renal IRI was examined with different ischemic durations. We found that the mice with <2 h of cold ischemia exhibited no significant changes in renal function or histopathology; animals with 3 or 4 h of cold ischemia developed into mild to moderate acute kidney injury with characteristic features, including the elevation in plasma creatinine concentration and reduction in glomerular filtration rate and tubular necrosis, followed by a subsequent recovery. However, mice with 5 h of cold ischemia died in a few days with severe acute kidney injury. In summary, we generated a mouse model of renal IRI induced exclusively by cold ischemia, which mimics graft cold storage in preservation solution, and renal function can be evaluated in vivo.
Keywords: cold ischemia; ischemia-reperfusion injury; kidney transplantation.