Serial evaluation of segmental esophageal reconstruction using a polyurethane scaffold in a pig model.

Background: Many esophageal pathologies are clinically treated by resection and reconstruction of the esophagus. Surgical esophagectomy remains a morbid procedure and despite minimally invasive advances, has changed little in decades. Novel approaches to esophageal segmental resection and reconstruction are an unmet need. Methods: Circumferential thoracic esophageal transection was performed in both male and female pigs and the defects reconstructed using 5 or 10 cm polyurethane (PU) tubular grafts and stented. A subset were treated with stent only. Animals were survived to 14, 30, 60, and 399 days. Tissues were evaluated histologically, and via non-invasive serial endoscopy and contrast swallowing studies in long-term animals. Results: Luminal patency was achieved in all animals with no clinical evidence of leak. In short-term animals, there was healing noted in all cases with a variably sized region of ulceration remaining at the most central part of the repaired tube (between the proximal and distal anastomosis). In four long-term animals following stent removal, two resumed normal diet and thrived, while two animals were euthanized prior to the proposed endpoint because of stricture formation and inability to tolerate a normal diet. Re-epithelialization was observed in all groups, and more complete over time. Conclusions: The PU scaffold provides a matrix across which formation of new tissue can occur. The mechanisms through which this happens remain unclear, but likely a combination of fibrosis and tissue contraction, in conjunction with new tissue formation.

Long-term regeneration and remodeling of the pig esophagus after circumferential resection using a retrievable synthetic scaffold carrying autologous cells.

Treatment of esophageal disease can necessitate resection and reconstruction of the esophagus. Current reconstruction approaches are limited to utilization of an autologous conduit such as stomach, small bowel, or colon. A tissue engineered construct providing an alternative for esophageal replacement in circumferential, full thickness resection would have significant clinical applications. In the current study, we demonstrate that regeneration of esophageal tissue is feasible and reproducible in a large animal model using synthetic polyurethane electro-spun grafts seeded with autologous adipose-derived mesenchymal stem cells (aMSCs) and a disposable bioreactor. The scaffolds were not incorporated into the regrown esophageal tissue and were retrieved endoscopically. Animals underwent adipose tissue biopsy to harvest and expand autologous aMSCs for seeding on electro-spun polyurethane conduits in a bioreactor. Anesthetized pigs underwent full thickness circumferential resection of the mid-lower thoracic esophagus followed by implantation of the cell seeded scaffold. Results from these animals showed gradual structural regrowth of endogenous esophageal tissue, including squamous esophageal mucosa, submucosa, and smooth muscle layers with blood vessel formation. Scaffolds carrying autologous adipose-derived mesenchymal stem cells may provide an alternative to the use of a gastro-intestinal conduit for some patients following resection of the esophagus.

Full-thickness oesophageal regeneration in pig using a polyurethane mucosal cell seeded graft.

Malignant oesophageal pathology typically requires resection of a portion of oesophagus. The aim of this study was to investigate attachment and growth of swine oesophageal mucosal cells on electrospun synthetic nanofibre matrices of varying chemistries and to determine whether a mucosal-seeded graft, in a swine animal model, could induce regeneration. Swine mucosal oesophageal cells were isolated and seeded them onto five different matrix materials. Matrix samples were cultured for up to 14 days, after which matrices were analysed for cell attachment. Attachment varied for each of the matrix materials tested, with the most rigid showing the lowest levels of attachment. Importantly, sections of these matrices illustrated that multiple layers of mucosal cells formed, mimicking endogenous oesophageal structure. A tdTomato reporter line (mucosaltdt cells) was created to enable cell tracking. As polyurethane matrix was found optimal through in vitro testing, a graft was prepared using mucosaltdt cells, along with an unseeded control, and implanted into swine for determination of oesophageal regeneration. Mucosal seeded polyurethane grafts initiated full thickness regeneration of the oesophagus, including epithelial, submucosal, and skeletal muscle layers which were highly vascularized. Interestingly, an unseeded graft showed similar regeneration, indicating that the role of cells in the process of oesophageal regeneration is still unclear. The electrospun polyurethane matrix does appear suitable for multilayered cellular attachment and growth of oesophageal mucosal cells, and implantation of polyurethane grafts initiated full thickness regeneration of the oesophagus, indicating potential for oesophageal reconstruction in humans. Copyright © 2016 John Wiley & Sons, Ltd.