Generation of Mouse Proximal Colon Loop Model: A Surgical Procedure to Generate Proximal Colon Loop and Measure Intestinal Permeability by Detection of Fluorescent Markers in Serum Following Intraluminal Injection

Prepare the mouse for surgery and exteriorize the caecum. Using wet cotton swabs, exteriorize the entire ileum and place it on top of a wet cotton gauze. Identify the proximal colon into the blood supply located in the mesocolon. Mobilize the proximal colon, and create the first ligature in an area free of vessels in the mesocolon, at about 0.5 centimeters distal from the caecum.

Measure 2 centimeters from the first ligature, and create a second ligature at an area free of blood supply in the mesocolon. Using fine scissors, carefully cut next to each ligation to isolate a 2-centimeter-long pcLoop.

Gently flush the pcLoop with warm HBSS to remove feces using a flexible yellow feeding tube attached to a 10-milliliter syringe. Make sure to flush the luminal contents out of the abdominal cavity to keep the surgical site clean. Then, ligate the two cut ends of the flushed pcLoop using silk suture.

Use a 1-milliliter syringe with a 30-gauge needle to slowly inject 200 microliters of reagent such as FITC-dextrans or chemokine into the intestinal lumen. The pcLoop will inflate, causing a moderate distension of the mucosa. Use wet cotton swabs to gently put back the ligated pcLoop, ileum, and caecum. Close the abdominal wall using a needle holder, anatomical forceps, and 3.0 non-absorbable silk sutures with a reverse cutting needle.