Histologic assessment of bronchial anastomotic healing in canine lung transplantation

Postoperative wound healing of the bronchial anastomosis was studied in dogs with autotransplantation (20 dogs, 7 days to 6 years postoperatively) and allotransplantation (62 dogs, 5 to 174 days postoperatively) of the left lung. In the group undergoing lung allotransplantation, the relationship among three histologic parameters was studied: the grade of lung allograft rejection, the degree of changes in the epithelium, and submucous lymphocyte infiltration along the donor bronchus within approximately a 0.5 cm area distal to the anastomosis. In lung autotransplantation, mucosal continuity began to be observed 1 week postoperatively. Mucosal continuity and apparent collagen formation on any bronchial contiguous site were demonstrated in most animals studied more than 3 weeks postoperatively. Bronchial anastomotic healing tended to be slower in lung allotransplantation than in autotransplantation, although a mucosal continuity at the anastomosis was sporadically observed in immunosuppressed dogs surviving more than 3 weeks postoperatively with a lung allograft. There were significant rank correlations among the three histologic parameters, which showed that lung allograft rejection is closely connected with wound healing of the bronchial anastomosis in lung allotransplantation. Meticulous mucosal approximation is most necessary during bronchial anastomotic procedures. Establishment of an exact method for early monitoring of lung allograft rejection is absolutely necessary for lung allotransplantation.