Experimental study of tracheal allotransplantation with cryopreserved grafts

Objective: Tracheal reconstruction is necessary in patients with extensive tracheal stenosis caused by neoplasm, trauma, and congenital disease. We investigated the possibility of tracheal allotransplantation with cryopreserved grafts in a canine model. Methods: A seven-ring section of thoracic trachea was removed in 19 adult mongrel dogs. In group A (n = 4), a five-ring tracheal autograft was implanted. In group B (n = 6), a five-ring allograft was implanted with immunosuppression. In group C (n = 9), a five-ring cryopreserved tracheal allograft was implanted without immnnosuppression, Omentopexy wrapping around the grafts and both anastomotic sites was used in all animals, Results: All grafts survived without any evidence of atrophy or stenosis in group A. All animals in group B died of severe airway obstruction within 1 month, and postmortem examination of these grafts showed epithelial defect and necrotic tracheal cartilage in the scar tissue. In group C, no animals died of asphyxia caused by severe stenosis of the grafts. The graft epithelium was no longer present 20 days after transplantation, and the graft was covered with regenerated epithelium within about 60 days after the operation. Conclusion: These findings show that cryopreserved tracheal allografts cam be transplanted by means of omentopexy without immunosuppression and that cryopreservation may reduce tracheal allogenicity.