Infiltrating recipient mesenchymal cells form the obliterative airway disease lesion and dramatically remodel graft tissue in a model of chronic lung rejection

0 BLITERATIVE bronchiolitis (OB) has emerged as the main cause of long-term morbidity and mortality following lung transplantation.’ Our laboratory has developed a novel model of obliterative airway disease (OAD) in which rat tracheal allografts, but not isografts, heterotopitally implanted into the greater omentum, develop fibroproliferative lesions by day 28 that are histologically similar to those seen in clinical 0B.2.’ The predominant cells in the OAD lesion are spindle cells resembling fibroblasts or myofibroblasts; however, the origin of these cells is unknown. The purpose of this study was to identify the origin of these lesional cells and to characterize the temporal pattern of recipient and donor cell infiltration and proliferation relative to the temporal development of luminal obliteration, respiratory epithelial loss, and other characteristics of progrcssivc OAD.