Morphologic Assessment of Polycaprolactone Scaffolds for Tracheal Transplantation in a Rabbit Model

The purpose of this study was to clarify whether a polycaprolactone (PCL)-framed porous tracheal scaffold could be used for the replacement of the trachea in rabbits and produce better results in terms of luminal epithelialization. The tracheal scaffold consists of a PCL-framework and a collagen layer. After a longitudinal cervical skin incision, the trachea was exposed and a rectangular defect (1x0.5 cm) was created on the cervical trachea by a scalpel on eight rabbits. PCL-scaffold was trimmed and fixed to defect boundaries with Tisseel. Postoperatively, the site was evaluated endoscopically and histologically. Bronchoscopic examinations at 1 week revealed that implant exposure was recognized in the entire length of the prosthesis. The luminal surface of the implanted scaffold was partially covered at 2 weeks and completely covered at 4 weeks. Histologic data showed that the epithelial lining was nearly completed 1 week after surgery and some inflammatory cells were seen in the submucosa. At 2 weeks, the epithelium was already covered and the migration of inflammatory cells was not observed. However the concentration of cilia was not observed at this week. At 8 weeks there was also a neovascularization with luminal epithelialization. These findings suggest that a PCL-framed porous tracheal scaffold used in our experiment is an effective way to regenerate the epithelium on the surface of an artificial trachea.