Experimental Repair of Tracheal Defect Using a Bioabsorbable Copolymer

BackgroundWe investigated epithelialization and newly formed cartilage in an artificial trachea constructed using a bioabsorbable copolymer.Materials and MethodsFifteen male Japanese white rabbits (2.5–2.8 kg) were divided into three groups. A full-thickness anterior defect (4 mm × 10 mm) was created in the trachea. The defect was implanted with one of the following bioabsorbable copolymers: caprolactone-lactide copolymer sponge sheet reinforced with poly(glycolic acid) fiber mesh (Cop) (n = 6, group A), Cop-incorporating gelatin hydrogel (n = 4, group B), and Cop-incorporating gelatin hydrogel with 100 μg of basic fibroblast growth factor (n = 5, group C). Each trachea was reinforced with an external nondegradable polymer stent. Three rabbits in each group were sacrificed at 1, 3, and 6 mo postoperatively and the trachea was evaluated histologically; other animals were sacrificed up to 12 mo postoperatively.ResultsIn groups A, B, and C there were two, one, and one postoperative deaths, respectively. In group A, epithelialization was recognized from 1 mo to 12 mo postoperatively, but no new cartilage was formed during the 12 mo following implantation. In group B, epithelialization was recognized 3 and 6 mo postoperatively, and new cartilage was detected at 6 mo after the operation. In group C, newly formed cartilage and epithelialization were observed 3, 6, and even 12 mo postoperatively. Furthermore, neovascularization was observed in groups B and C.ConclusionsA bioabsorbable copolymer incorporating gelatin hydrogel induces tracheal epithelialization and formation of cartilage and vessels in tracheal defects, and could be available for clinical use in children.