An Effective Mouse Model of Unilateral Renal Ischemia-Reperfusion Injury

Renal ischemia-reperfusion injury is the leading cause of acute renal failure. This model is very helpful for understanding the pathophysiological changes that occur in the kidney after an ischemic insult. This model is time and cost effective and delivers highly reproducible data.

In addition to this, this Unilateral Renal Ischemia Model allows the researcher to work with longer ischemic times while maintaining a high survival rate. To begin with, place the anesthetized mouse on the operation table. After sterilizing the surgical area, use a scalpel blade to make an approximately one-centimeter dorsal lateral surgical incision on the right flank behind the rib and continue coddley approximately one centimeter parallel to the lumbar midline.

Transect the abdominal musculature using scissors to visualize the retroperitoneal space. Use a sterile cotton swab to remove the small amounts of blood produced during the sectioning of the muscles. Next, push the right kidney out from the abdominal cavity.

Slowly and carefully expose the kidney with gray forceps and identify the renal pedicle. Then carefully remove the adipose tissue around the pedicle. Use a Halsted Mosquito Hemostat for manipulating the vascular clamp.

For inducing the ischemia, place the vascular clamp over the renal artery and vein present in the renal pedicle avoiding clamping the adjacent ureter. Cover the clamped kidney with sterile gauze soaked in saline to avoid desiccation. Leave the kidneys on the gauze for 30 minutes and monitor the anesthesia depth and humidity of the gauze periodically.

Shortly before the end of the ischemia period, uncover the kidney and hold the Halsted Mosquito Hemostat, ready for clamp removal. At the end of the ischemia period, open the vascular clamp with the hemostat and remove the clamp to allow perfusion of the kidney. For sham control animals, perform the demonstrated surgery without clamping of the renal pedicle.

After verifying the kidney color change, return the kidney to the abdominal cavity. Close the abdominal muscles in a cruciate pattern with absorbable suture 5-0. Close the skin in a horizontal mattress pattern with absorbable suture 5-0.

Clean the wound with povidone-iodine solution. After the ischemia perfusion injury, body weight reduction was seen in some mice with less than 10%of the initial body weight. However, most mice recovered their initial body weight between days 4 and 7 postsurgery.

The control mice did not show any body weight changes post-surgery. Several changes in the renal morphology post-surgery were identified using hematoxylin-eosin, Periodic acid-Schiff, and Masson's Trichrome staining. The presence of proteinaceous cast in the tubular lumen was observed after four hours.

Tubular dilation was detected at eight hours and tubular cast as well as cellular necrosis in the medullary segments were noticed at 16 hours post IRI surgery. After 24 hours of the surgery, tubular dilation was observed. Infiltration of lymphocytes and macrophages and enlarged cell nuclei were detected after 48 hours.

By day 4, mitotic tubular cells were observed and at day 7 post-IRI surgery, focal fibrosis was detected. The renal cortex of the mice during early reperfusion was monitored using PAS staining and progressive attenuation of the brush border was visible. The areas of interstitial fibrosis at day 7 post-surgery were visualized using Masson's Trichome staining.

A tubular injury scoring system was developed to categorize the damage over time. The highest tubular injury scores were obtained between 8 hours and 24 hours following Renal IRI. Some of the most critical steps are the correct placement of the vascular clamp in the renal pedicle and maintaining a constant body temperature during the surgery.