Study of the development and evolution of neointestine in a rat model

The implantation of fragmented rat intestinal epithelium into the omentum of syngeneic animals results in the formation of a cyst containing neointestine. The purpose of our project was to study the evolution of this neointestine-containing cyst over time. Harvested jejunum and ileum of neonatal DA rats (6 to 8 days old) was digested with collagenase type XI and dispase at room temperature. The resulting organoid units, containing clusters of intestinal epithelium with stem cells were seeded onto a polyglactin polymer mesh (100000 units per mesh). The absorbable mesh was implanted in the omentum or peritoneal wall of an adult syngeneic animal. Animals were sacrificed at weekly intervals to harvest the neointestinal cysts. The lumen of the neointestine cysts was full of mucous while the wall of the cyst was covered by intestinal mucosa. H&E staining of the cyst demonstrated the morphology of intestinal epithelium; PAS staining identified goblet cells. The size of the cyst was maximal between 4 and 8 weeks postimplantation tending to regress thereafter. Neointestinal cysts are a consistent finding after implantation of intestinal epithelium organoids into the omentum or peritoneal wall in the rat model. The cysts reach a maximal size at 4 to 8 weeks postimplantation, tending to regress thereafter.