Extra Luminal Demucosalisation of the Colon
Purpose The standard technique used to create a demucosalised colonic segment is to open the bowel and excise mucosa from within the lumen. Long-term results have demonstrated both fibrosis and contraction, and regrowth of colonic epithelium in these segments. We postulated that crypt remnants contribute to the epithelial repopulation. The aim of this study was to create a seromuscular graft from the bowel exterior, with the aim of efficiently removing the epithelium and hence preventing colonocyte regrowth. Material and Methods Pilot studies were performed on euthanased pigs to optimise the technique and tissue samples examined by immunohistochemistry. In vivo, vascularised seromuscular colonic grafts were created from the bowel exterior in seven large white hybrid pigs and combined with autologous tissue-engineered urothelium to augment the bladder by composite cystoplasty. The dissection was facilitated by placing an inflated Foley catheter within the colonic lumen. The seromuscular ends were approximated with 5/0 Vicryl® sutures and excess mucosa intususcepted within the lumen. Pigs were sacrificed at 3 months and the reconstructed bladder segments examined histologically to determine epithelial phenotype. Results Pilot studies showed that the technique was successful in creating seromuscular segments with no epithelial remnants. At 3 months, all bladder specimens showed urothelium lining the augmented segments. There was no evidence of fibrosis or colonocyte regrowth. Conclusions Extra-luminal dissection creates robust seromuscular segments for use in bladder augmentation and prevents both regrowth by colonic epithelial cells and contamination of the graft by exposure to the bowel contents. This technique could find application in bladder reconstruction techniques including composite cystoplasty and autoaugmentation.