Surg Today (2002) 32:493–497 Successful Tracheal Transplantation with Fresh Allografts in a Rabbit Model Erkan Di . kmen 1 , Murat Kara 1 , Hüseyi . n Çakmak 1 , Di . clehan Orhan 2 , Ayli . n Okçu Heper 2 , and Adem Güngör 1 Departments of 1 Thoracic Surgery and 2 Pathology, Ankara University School of Medicine, I . bn-i Sina Hospital, TR-06100, Sıhhiye, Ankara, Turkey Key words Trachea · Allograft · Transplantation Introduction Although resection followed by end-to-end anastomotic reconstruction of the trachea is feasible, the use of a tracheal graft becomes indispensable to restore the re- spiratory conduit following resection of more than 50% of the trachea. 1 Investigations on tracheal substitution achieved by a prosthesis, autogenous tissue, or an allo- transplant have been carried out, but as yet it remains a clinically unsolved surgical problem. Several studies on prosthetic grafts have been reported with unsatisfactory results. 2–4 Similarly, repair of the tracheal defect with autogenous tissue usually results in failure because of the difficulty in maintaining a patent airway. 5–7 Further- more, autogenous tissue transplantation is a compli- cated and multistaged procedure, which makes its use of limited value in clinical application. 2,8 For these reasons, tracheal allotransplantation appears to be the most promising method for tracheal replacement. The major obstacles for a successful tracheal allo- transplantation involve the immunogenicity and res- toration of adequate blood supply to the donor graft. 9,10 Thus, vascularization procedures and immunsup- pression may help the allograft to retain its viability. On the other hand, as the trachea is a comparatively simple organ and with low immunogenicity, restoration of the blood supply has become a more challenging problem. Hence, attempts have been focused on achieving ad- equate vascularization of the donor graft for successful tracheal allotransplantation. In the present study, we investigated the histomor- phological changes related to the revascularization and immunogenic effects of fresh allografts after tracheal allotransplantation in 20 rabbits of a genetically similar strain. Abstract 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 re- action of the fresh allografts after tracheal transplanta- tion. Histomorphological assessment was conducted by investigating the anastomotic sites, graft necrosis, and epithelization. Cellular changes, including the infiltra- tion of granulocytes, histiocytes, and fibroblast prolif- eration related to a granulation tissue-like reaction, were also assessed, with lymphocyte infiltration which is an indicator of graft rejection. All of these characteris- tics, apart from epithelization, were graded semiquan- titatively as none (0), mild (1), moderate (2), and severe (3). Epithelization was graded as 0, indicating no epithe- lization; 1, 20%; 2, 40%; 3, 60%; 4, 80; 5, com- plete epithelization of the entire graft. Results. Morphologic integrity of the trachea was com- pletely 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 infiltra- tion 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. Reprint requests to: M. Kara, Güvenlik Caddesi, Esenlik sokak 7/10, TR-06540, As ¸ ag ˘ ıayrancı, Ankara, Turkey Received: March 1, 2001 / Accepted: November 20, 2001