EXPERIMENTAL TRACHEAL AND TRACHEOESOPHAGEAL ALLOTRANSPLANTATION

We investigated the effects of allograft perfusion with a preservative technique and of combined thyrotracheoesophageal implantation on airw ay epithelium of long segments of thyrotracheal grafts allotransplante d on their own vascular pedicles into immunosuppressed pigs, Four grou ps of five animals each underwent heterotopic (into the neck) thyrotra cheal (group 1) and thyrotracheoesophageal (group 2) and orthotopic th yrotracheal (group 3) and thyrotacheoesophageal (group 4) allotranspla ntation. Allograft revascularization included (1) interposition of don or right subclavian artery-incorporating the inferior thyroid artery-t o recipient right carotid artery (end-to-end fashion) and (2) end-to-s ide anastomosis of donor anterior vena cava to recipient right externa l jugular vein, All thyrotracheoesophageal blocks were harvested after inferior thyroid artery perfusion with 4 degrees C Euro-Collins solut ion, The overall lengths of tracheal and esophageal grafts were 10.7 /- 2.7 cm and 13.4 +/- 3.6 cm, respectively, In the heterotopic groups , all allografts were viable and histologically normal at postmortem e xamination and the incidence and severity of airway ischemia and rejec tions (at equal residual levels of cyclosporine) were not different be tween groups 1 and 2. In the orthotopic groups, the first two pigs die d of airway collapse dth histologically normal grafts, In the remainin g pigs, temporary airway stenting was inserted and allografts remained viable and histologically intact for their entire length 30 days afte r transplantation. Transplanted tracheal smooth muscles had concentrat ion-dependent contractions and relaxations similar to those of nontran splanted (native) tracheas. This study documents the feasibility of al lotransplanting long tracheal and esophageal segments on their own vas cular pedicles and demonstrates that allograft preservation and thyrot racheoesophageal transplantation are equally effective in minimizing a irway ischemia, Thyrotracheo-esophageal transplantation does not enhan ce recipient alloimmune response compared with thyrotracheal transplan tation alone.