Tracheal replacement using an aortic graft.

Tracheal replacement remains an unsolved problem and one of themain challenges in thoracic surgery. More than 50 years of researchdid not provide an ideal synthetic or biologic substitute. We proposedan original solution : the use of an aortic graft. Methods :Fifty-one sheep were operated in 3 successive studies : replacementof the anterior segment of two tracheal rings (n=10), tracheal replacementusing an aortic autograft (n=21) or allograft (n=20). Atracheal stent was placed for extensive replacements (n=41). Postoperativeevaluation included clinical, bronchoscopic and histologicexaminations with a 3-year maximal follow-up. In the last study, anaortic allograft from male sheep was used for the tracheal replacementin 6 female sheep. The use of the PCR technique (detection ofthe SRY gene of the chromosome Y) allowed to analyze the originof histologic transformations. Results : Postoperative course wasuneventful in 46 animals. There was no stenosis except for animalsof the first study, no anastomotic leakage, nor graft rupture. Removalof the stent was possible after 6 months. Histologic examinationsshowed a progressive transformation of the aortic graft into atracheal tissue with epithelium and newly formed rings of cartilage.Chromosome Y was not found in newly formed cartilage. Comment: This work showed a tracheal regeneration from an aorticgraft. The well-known possibilities of epithelial reparation from thenative trachea have been confirmed. The regeneration of cartilagewhich has never been observed with other substitutes, was possiblefrom recipient tracheal or circulating cells. These results offer majorperspectives in the comprehension of tissue regenerative processesand in human tracheal replacement.