Development of a porcine model for assessment of mucosal repair following endoscopic resection of the lower gastrointestinal tract

BACKGROUND AND AIMS: Endoscopic mucosal resection (EMR) is widely performed for the treatment of colorectal polyps. However, the pathophysiological mechanisms of mucosal repair, including in situations at high risk of post-polypectomy bleeding, remain largely unknown. The objective of our study was to develop a porcine model of EMR in the lower gastrointestinal tract to monitor mucosal wound healing over time. METHODS: Under general anesthesia, five large wounds were created in the lower gastrointestinal tract at different times, i. e. at day 0, 3, 7, 10, and 14, by multiband EMR, in each of the six pigs in the study. A colorectal resection was performed at day 14 and the animal euthanized. Repeated endoscopic and endomicroscopic examination, and histological analysis were performed. RESULTS: No complications occurred and all animals reached the study end point. The endoscopic aspect of wound healing evolved into different phases with first a fibrin deposit covering the wounds which then gave way to granulomatous tissue. The size of the wound regressed significantly as early as day 3. Re-epithelialization of the wound started from day 7, and neo-mucosal crypts appeared from day 10. The endomicroscopic analysis described a ‘ground glass appearance’ from day 3 and irregular crypts from day 10, which was consistent with histological data. Good agreement between macroscopic, endomicroscopic, and histological parameters of mucosal wound healing was observed in vivo. CONCLUSION: This study demonstrates for the first time the feasibility of an experimental in vivo porcine model of lower gastrointestinal endoscopic resections to monitor tissue repair. This model might be helpful to document pharmacological approaches for preventing complications of endoscopic procedures performed in humans.