Effects of anastomosis of tissue-engineered neointestine to native small bowel

Background. Our laboratory is investigating the tissue engineering of small intestine using intestinal epithelial organoid units seeded onto highly po rous biodegradable polymer matrices. This study investigated the effects of anastomosis of tissue-engineered intestine to native small bowel alone or combined with small bowel resection on neointestinal regeneration. Methods. Intestinal epithelial organoid units harvested from neonatal Lewis rats were seeded onto biodegradable polymer tubes and implanted into the o mentum of adult Lewis rats as follows: (1) implantation alone (n = 9); (2) implantation followed by anastomosis to native small bowel at 3 weeks (n = 11); and (3) implantation after small bowel resection and anastomosis to na tive small bowel at 3 weeks (n = 8). All constructs were harvested at 10 we eks and examined by histology. Morphometric analysis of the neomucosa was o btained using a computer image analysis program. Results. Cyst development was noted in all animals. All anastomoses were pa tent at 10 weeks. Histology revealed the development of a vascularized tiss ue with a neomucosa lining the lumen of the cyst with invaginations resembl ing crypt-villus structures. Morphometric analysis demonstrated significant ly greater villus number, villus height, crypt number, crypt area, and muco sal surface length in groups 2 and 3 compared with group 1, and significant ly greater villus number, villus height, crypt area, and mucosal surface le ngth in group 3 compared with group 2 (P < 0.05, ANOVA, Tukey test). Conclusion. Intestinal epithelial organoid units transplanted on biodegrada ble polymer tubes can regenerate into complex tissue resembling small intes tine. Anastomosis to native small bowel combined with small bowel resection and anastomosis alone contribute significant regenerative stimuli for the morphogenesis and differentiation of tissue-engineered neointestine. (C) 19 99 Academic Press.