Reimplantation response in isografted rat lungs. Analysis of causal factors

The function of transplanted lungs may be critically impaired in the early postoperative period by the reimplantation response. Several factors of the transplantation procedure, such as disruption of hilar structures (hilar stripping), stenotic anastomoses, and graft ischemia, are considered to cause this reimplantation response. In this study the individual contributions of these factors have been analyzed in rats, after isogeneic transplantation or hilar stripping of left lungs. Marck's technique for orthotopic transplantation of the left lung in rats was refined so that an 85% postoperative survival rate was achieved. Transplanted and hilar-stripped lungs were investigated by lung perfusion scintigraphy and chest roentgenography at regular intervals up to 168 days after operation. Macroscopic and histologic morphology was examined at corresponding intervals. Our results show that perfusion and ventilation of lung grafts are independently affected by distinct factors of the transplantation procedure. Hilar stripping did decrease graft perfusion transiently. Permanent decrease of perfusion was found to be caused by stenosis of the anastomosed pulmonary artery. Hilar stripping also impaired ventilation, by causing interstitial and alveolar edema. After transplantation, edema and consequent impairment of ventilation were aggravated by graft ischemia, proportionally to its duration. Our improved technique for transplantation of left lungs in rats provides a new opportunity for investigating the immunologic problems of lung transplantation.