Novel isolated cecal pouch model for endoscopic observation in rats.

aimTo create a new rat model for drug administration, cell transplantation, and endoscopic examination for the treatment of intestinal diseases.

methodsF344/NJc l-rnu/rnu rats (10-wk-old males, 350-400 g) were used in this study. The rats were anesthetized via 2% isoflurane inhalation. The rat's cecum was isolated from the intestines, and a pouch was created. The remainder of the intestines was rejoined to create an anastomosis. The "side-to-side" anastomosis (SSA) technique initially involves the creation of a 2-cm longitudinal incision into each intestinal wall. To create an anastomosis along the ileal and colonic walls, both intestines were cut, and a continuous suture procedure was performed that included all layers of both intestines. The serous membrane was sutured along the edge and on the anterior wall of the anastomosis. The "end-to-end" anastomosis (EEA) technique was compared with the SSA technique. In the EEA technique, the frontal surfaces of both cut intestinal lumens were joined together by continuous sutures. Additional sutures were made at the serosa. After the anastomotic intestine was successfully constructed, the two intestinal lumens that were cut at the isolated cecum were managed. In addition, one luminal side of the pouch remained open to create an artificial anus on the dorsum as a passage for the residual substances in the pouch. Finally, small animal endoscopy was used to observe the inside of the pouch.

resultsIn this animal model, mucus and feces are excreted through the reconstructed passage. Accordingly, the cecal pouch mucosa was not obstructed or contaminated by feces, thus facilitating observations of the luminal surface of the intestine. The endoscopic observation of the cecal pouch provided clear visualization given the absence of feces. The membrane surface of the cecum was clearly observed. Two methods of creating an anastomotic intestine, the "SSA" and "EEA" techniques, were compared with regard to animal survival rate, complication rate, and operation time. The SSA technique resulted in a significantly increased survival rate and a lower incidence of complications in rat models compared with the EEA technique. The complications of stenosis and leakage resulted in death in the EEA technique. Thus, the EEA technique exhibited a lower survival rate compared with the SSA technique. However, the SSA technique required a significantly longer operation time compared with the EEA technique.

conclusionOur new rat model is potentially useful for the development of a novel treatment for intestinal diseases.