Experimental Tracheal Transplantation Using a Cryopreserved Aortic Allograft

Abstract

Background: The tracheal reconstruction after wide resections remains a critical surgical problem. Our aim was to replace trachea with a tissue easy to vascularize, which allows a simple reconstruction and does not require an immunosuppressive regimen. Materials and Methods: A segment of cryopreserved aorta was used in order to verify its adequacy as tracheal substitute. In phase 1, the thoracic aorta of 10 rabbits was excised, obtaining 20 segments that were cryopreserved. Ten segments were implanted in the omentum of 10 rabbits that were sacrificed on postoperative days 7, 14 and 21, and the grafts were examined histologically. In phase 2, a segment of cryopreserved aorta arranged with a silicone prosthesis was transplanted in 10 rabbits and wrapped with omentum. The animals were sacrificed on postoperative days 7, 14 and 21. Results: In phase 1, the neovascularization of the grafts was present after 7 days, and after 14 days the fibroblasts invaded the lumen of the aorta. In phase 2, 8 rabbits survived and the histologic examination after 7, 14 and 21 days showed neovascularization, the absence of rejection and the proliferation of fibroblasts inside the lumen of the aorta; this growth has been restrained by an endoluminal prosthesis. Conclusions: Our study demonstrated that replacing the trachea with cryopreserved aorta is technically feasible and does not evoke immunologic reactions. It requires, however, a silicone tube inside the allograft to limit the colonization of fibroblasts.

Tracheal reconstruction with a composite graft: fascial flap-wrapped allogenic aorta with external cartilage-ring support

“…This detrimental role of a potentially contaminating environment is supported by the fact that the most necrotic graft lesions were observed in the animals that experienced wound complication after the flap wrap procedure. Survival after tracheal replacement ranged from 8 to 47 days, with a 3-week mortality rate of 40%, in line with data from either tracheal transplantation or replacement in rabbit models showing a 3-week mortality rate of 43-100% (Table 3) [11,[21][22][23][24]. Given the short survival with no technical possibility of bronchoscopic stent removal, we were not able to investigate whether the respiratory epithelium regenerated or if scar tissue formed within the lumen of the neo conduit such as previously described by Carbognani et al [21] after tracheal replacement with cryopreserved AA, and Weidenbecher et al [24] after tracheal replacement using a tissue-engineered cartilage graft, respectively [21,24].…”

“…We hypothesize that the environment of the graft might play a major role. In a heterotopic position and inside a sterile environment, the observed inflammatory reaction, mainly composed of polymorphonuclear [21] TR with cryopreserved allogenic aorta 10 1 18 a Dodge-Khatami et al [22] TR (silicone-metallic prosthesis) 7 -3 b Tanaka et al [23] Tracheal transplantation (cryopreserved allografts) 7 -3 Weidenbecher et al [24] TR (tissue-engineered composite graft) 6 -4 Present study TR (composite graft: AA and cartilage rings) leucocytes, was moderate, and associated with moderate to complete aorta necrosis, and complete conservation of the cartilage viability. In an orthotopic position, the graft was exposed to oro-pharyngo-tracheal microbiological contamination.…”

Tissue Engineered Trachea Using Decellularized Aorta

“…However, this established method is not appropriate for the repair of extensive lesions. Therefore, for these types of lesions other replacement methods, such as autografts [2,3], allografts [4,5], prosthetics materials [6][7][8] and tissue engineering [9][10][11][12] have been studied and developed. Some partial successes have been announced with some of these methods, butso far not one of them has archived a completely satisfactory long-term tracheal replacement for extensive lesions of the trachea.…”

Cryopreservation of the tracheal grafts

“…[7][8][9] However, most of these prosthetic tracheal grafts failed to reepithelialize. [9][10][11] The repair of tracheal defects with autogenous tissue, such as free periosteal, 12 jejunal, 13 muscular, 14 esophageal, 15 bronchial 16 and aortic 17 grafts also has met with limited success because of difficulties in maintaining a patent airway. In contrast, a tracheal allograft contains native epithelium and has cartilaginous rings to maintain a patent airway.…”