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

During pathological conditions, impaired intestinal epithelial tight junction barrier causes increased permeation of harmful luminal contents into systemic circulation, resulting in increased systemic inflammation.

To assess intestinal permeability by generating an intestinal proximal colon loop or pcLoop model, prep an anesthetized mouse in the supine position. Perform a midline abdominal incision. Gently exteriorize the cecum, terminal ileum, and proximal colon, placed over wet gauze to maintain organ hydration.

Locate the proximal colon’s mesocolon — membranous folds of peritoneum containing blood vessels. Identify two sites appropriately apart in the mesocolon free of blood vessels, distal from the cecum, to be ligated. Perforate the sites.

Creating the ligature in the selected sites, make incisions close to the ligated sites to isolate a pcLoop segment without disturbing the blood supply. Flush the segment with buffer to remove any fecal matter.

Surgically tie up the cut ends of the flushed segment. Inject desired fluorescent-marker solution into the colon segment lumen. Return the organs into the abdominal cavity. Close the surgical incision and allow the mouse to recover.

Following injection, reduced intestinal barrier integrity facilitates increased paracellular transport of the fluorescent marker molecules from the intestinal lumen into the blood circulation, which can be detected in the serum fraction of blood to measure the intestinal permeability.