Successful tracheal transplantation with fresh allografts in a rabbit model

Purpose. Immunogenicity and the restoration of blood supply to the donor graft remains a clinical challenge in tracheal allotransplantation. We conducted a study on 20 rabbits of a genetically similar strain to eliminate the risk of rejection caused by immunogenicity. Methods. We examined the histomorphological changes related to revascularization and the immunogenic reaction of the fresh allografts after tracheal transplantation. Histomorphological assessment was conducted by investigating the anastomotic sites, graft necrosis, and epithelization. Cellular changes, including the infiltration of granulocytes, histiocytes, and fibroblast proliferation related to a granulation tissue-like reaction, were also assessed, with lymphocyte infiltration which is an indicator of graft rejection. All of these characteristics, apart from epithelization, were graded semiquantitatively as none (0), mild (1), moderate (2), and severe (3). Epithelization was graded as 0, indicating no epithelization; 1, ≤20%; 2, ≤40%; 3, ≤60%; 4, ≤80; 5, complete epithelization of the entire graft. Results. Morphologic integrity of the trachea was completely retained in 16 (80%) animals. The overall rating score of epithelization was 3.6 ± 1.0, while those of the granulation tissue-like reaction and lymphocyte infiltration were 4.8 ± 0.6 and 1.5 ± 0.7, respectively. Conclusion. These findings demonstrate that tracheal allotransplantation is possible with fresh allografts in genetically similar strains of rabbits.