Murine Model of Islet Transplantation: A Surgical Method to Infuse Pancreatic Islets in Portal Vein and Prevention of Postoperative Bleeding

In a mouse model of insulin-dependent diabetes, pancreatic islets are injected via the hepatic portal vein for therapeutic purposes. The beta cells within the islet cluster produce insulin, a hormone that regulates blood glucose levels.

Intraportal injection is a simple and effective technique, but postoperative bleeding often leads to the death of the model animal. To prevent this complication, prep an anesthetized mouse in the supine position. Shave the abdominal area and apply a disinfectant solution. Make an incision to expose the peritoneal cavity. Exteriorize the intestines from the peritoneal cavity on a moist gauze to expose the underneath portal vein.

Take an insulin syringe pre-loaded with islets. Insert the needle directly parallel into the portal vein, with its bevel facing down. Draw some blood into a syringe to mix the islets, and then inject slowly. Pull and push the plunger multiple times to infuse the entire islet suspension. Now, place a gelatin sponge to cover the injection site.

Gelatin, a hemostatic matrix, absorbs blood and swells to form a stable clot over the puncture site, thereby arresting the bleeding. Next, return the intestine into the peritoneal cavity and suture the incision. Return the mouse to its home cage and regularly monitor for signs of recovery.

After confirming a lack of response to pedal reflex, apply ointment to the eyes to prevent drying. Shave the abdomen of the anesthetized mouse to remove the fur, and disinfect the surgical area with three alternating wipes of 2% iodine and 75% alcohol.

Next, make a 1 to 1.5 centimeter incision in the abdomen, and open the peritoneal cavity. Place a sterile piece of gauze around the incision and use forceps or cotton tips to gently transfer the intestine onto the gauze. Then, cover the intestine with a piece of saline-soaked gauze, and expose the portal vein.

To stop islet transfer-induced bleeding using gel foam, hold the needle with the bevel facing down, and position the needle tip with the opening parallel to the portal vein wall. Before inserting the needle into the portal vein, retract the plunger to draw a 20 to 50 microliters of blood into the syringe to mix with the islets before infusing the islets into the portal vein while repeatedly depressing and retracting the plunger.

When all of the islets have been delivered, place approximately 0.5 x 0.5 centimeter piece of gel foam over the injection site. Use a cotton tip to press the gel foam down, while removing the needle from the portal vein. Hold the gel in place for about two minutes, rolling the gel foam to make sure it covers the portal vein.

Once the bleeding has stopped, gently return the intestine to the peritoneal cavity in the original position and inject 500 microliters of warm saline into the abdominal cavity. Use sutures to close the muscle and skin layers. Then, place the mouse in a clean cage on a heating pad with monitoring until complete recovery from anesthesia, administering analgesia every 12 hours and heat for 48 hours.