Optical tissue window: A novel model for optimizing engraftment of intestinal stem cell organoids

Background. Intestinal malabsorption disorders and short bowel syndrome lead to significant morbidity. We recently demonstrated that grafting of intestinal organoids can grow a bioengineered intestinal neomucosa and cure bile acid malabsorption in rats. Now we have developed a novel system that permits direct observation of intestinal organoids in vivo to optimize conditions for engraftment. Methods. Optical Windows were created in C57BL/6J mice by externalizing an omental pedicle into a dorsal skin flap chamber. Following creation of windows, 5000 intestinal organoids from green-fluorescent protein transgene (GFP)(+) donor mice were seeded directly either on omentum or on polyglycolic acid (PGA) disks that had been placed on omentum at 1 or 5 days. Engraftment of green fluorescent cells was evaluated on postseeding days 1, 3, 5, 7, 10, 12, and 21 using fluorescence microscopy. Results. An initial group had seeding onto omentum (n = 5) or biopolymer disks (n = 5) on postoperative day 1. After 7 days, there was mucosal cell engraftment onto omental tissue and biopolymers. GFP(+) organoids engrafted significantly better when seeded onto biopolymers compared to omentum (P < 0.05). In a second study with increased sample size (n = 24) up to day 12, all four groups demonstrated adherence and growth. However, GFP(+) organoids seeded onto delayed PGA biopolymer demonstrated significantly better engraftment (P < 0.05). Conclusions. This novel system allows continuous in vivo observation of engrafted cells that are seeded on externalized omentum. The use of PGA mesh biopolymer may improve engraftment of intestinal organoids. (c) 2006 Elsevier Inc. All rights reserved.