Professor and Chairman The Icahn School of Medicine at Mount Sinai Icahn School of Medicine at Mount Sinai New York, Pennsylvania
Educational Objective: At the conclusion of this presentation, the participants should be able to understand the role of tracheal transplantation for the management of extensive airway defects.
Objectives: To review the clinical course, histological findings, cytogenetic characteristics, and immunological features of the allograft one year after performing a human vascularized tracheal transplantation.
Study Design: Case report.
Methods: One year ago, we performed a 9.5 cm vascularized tracheal transplantation to reconstruct an extensive tracheal airway defect that was not amenable to standard reconstructive techniques. The female patient was immunosuppressed with a regimen of tacrolimus, mycophenolate, and steroids. The donor was male. Endoscopy was performed regularly with narrow band imaging (NBI), endoscopic tracheal biopsies were performed on a regular basis with histology, electron microscopy, and fluorescence in situ hybridization (FISH) cytogenetics to demonstrate mucosal migration and allograft chimerism. Histology and free cell DNA were monitored to assess acute and chronic rejection.
Results: One year after tracheal transplantation with standard immunosuppression, the patient has not demonstrated evidence of acute or chronic rejection based on histology and free cell DNA testing. The allograft initially sloughed the ciliated epithelium which clinically manifested as a stasis of secretions for a 2 week period after transplantation. This was followed by a transient reepithelialization of the allograft with recipient derived epithelium and normal mucociliary transport resumed. FISH cytogenetic analysis demonstrated that recipient derived mucosa populated the allograft for 90 days, however after 90 days, the allograft epithelium reverted to donor derived mucosa.
Conclusions: Human vascularized tracheal transplantation represents a viable solution for long segment airway defects that are not amenable to standard reconstructive techniques. The allograft undergoes a transient repopulation with recipient derived mucosa resulting in an immunological chimera. The ability to maintain this chimeric state may represent an opportunity to deescalate or even mitigate systemic immunosuppression.