Our purpose is to determine the role of coagulation system activation and inadequate regulation within the pulmonary xenograft on endothelial cell activation, inflammatory augmentation and pulmonary xenograft injury. Initiation of the coagulation system coincides with the acute lung injury that is caused by a) ischemia-reperfusion b) complement activation c) probably antibody binding and d) the pro-coagulant and anti-fibrinolytic actions of pulmonary macrophages. Coagulation system dysregulation allows for uncontrolled acceleration of coagulation with cascading effects on the endothelial cell and the inflammatory system. Strategies to decrease the initiating events leading to activation of the coagulation system are our focus. We plan to 1) deplete the pulmonary macrophages by repetitive administration of intravenous liposomal clodronate to determine their role in initiation of the diffuse intravascular coagulation, endothelial cell activation, and pulmonary xenograft injury 2) determine the importance of xenoreactive antibody binding to Gala1 -3Gal epitopes in pulmonary xenograft injury by depleting antibody in the absence of complement activation using a-gal trisaccharide-PEG conjugates in conjunction with complement inhibition using C1-inhibitor and anti- C5a and 3) inhibit and regulate the coagulation system through the use of inhibition of tissue factor dependent activation of factors IX and X using TFPI or ASIS, and inhibition of factor VIlla and Va by Activated Protein C to assess the effects on endothelial cell function, inflammatory system activation and xenograft function.
