Reconstruction of trachea and carina with immediate or cryopreserved allografts in dogs

Background. Grafting is required when primary reconstruction of a tracheocarinal defect is not feasible. To determine the viability of and the nature of the healing process occurring in the cryopreserved graft, we performed tracheocarinal transplantation in dogs. Methods. We performed 32 tracheocarinal reconstructions in dogs using autotransplanted, immediately transplanted, or cryopreserved allografts. The viability of each graft was evaluated serially by fiberoptic macroexamination and by measurement of the tracheal mucosal blood flow using a hydrogen clearance method. In group A (n = 8), the tracheal carina was removed and reimplanted immediately. In group B (n = 8), the tracheocarina was allotransplanted immediately after harvest. In group C (n = 8), allotransplantations were performed using grafts cryopreserved for 1 to 3 weeks by freeze-drying. In group D (n = 8), we attempted to achieve immunosuppressionfree transplantation with the cryopreserved allografts. Results. Sufficient viability and good healing (6/8, 75%) occurred in the dogs with cryopreserved tracheocarinal allotransplants. Three of 8 dogs (38%) with cryopreserved allotransplants survived for 25 to 57 days without immunosuppression. Conclusions. The cryopreservation of tracheocarinal allografts for 3 weeks without the use of a preservative solution was shown to be feasible. Cryopreservation prolonged the survival of nonimmunosuppressed allotransplants in dogs.