Antibodies directed at various targets (especially Gal al,3Gal) and complement are pivotal mediators of hyperacute rejection of the heart, lung, and other organs. However in pig-to-human and pig-to-non-human primate models, we have consistently found that potent complement regulation coupled with efficient removal of anti-pig antibody is associated with rapid dysfunction of lung xenografts. Thus hyperacute lung rejection (HALR) is mediated by mechanisms in addition to those that cause hyperacute rejection of other organs. ? ? This paradigm is reinforced by the preliminary studies, where three GalT-KO swine lungs perfused ex vivo retained their function for an average of 2 hours (60, 134, and 170 minutes), far longer than controls (<10 minutes). Failure was due to sudden, rapid increase in pulmonary vascular resistance. Although biopsies obtained at 10 and 30 minutes of perfusion were histologically unremarkable, intravascular thrombi and capillary congestion were observed at graft failure, despite anticoagulation with high-dose heparin. Coagulation pathway activation (Fl+2) was delayed but not prevented, platelet activation (thrombospondin release) was not attenuated, and over 70% of platelets in the perfusate were sequestered in the lung within minutes of initiating perfusion. Complement activation and deposition in the lung, while reduced, were not prevented. Based on these observations and our previous work demonstrating pivotal roles for thrombin, platelets, complement, and pulmonary intravascular macrophages in hyperacute rejection of Gal+ lungs, we hypothesize that dysregulated intravascular coagulation and residual complement activation are the principle cause of acute injury of GalT KO pig lung xenograft. ? ? To test this hypothesis, a combination of genetic (GalTKO lungs expressing human tissue factor pathway inhibitor or decay accelerating factor) and pharmacologic approaches (specific platelet receptor, thrombin, or complement inhibitors) will be used in an established ex vivo perfusion model. Approaches that yield optimal lung function ex vivo will then be validated in vivo in a life-supporting pig-to-baboon lung xenograft model. As a result of the studies proposed, we anticipate that hyperacute lung rejection will be successfully prevented for the first time using primarily donor-directed, mechanism-based strategies to consistently achieve life-supporting function of a pig lung in a baboon, allowing subsequent immunologic barriers to be addressed in this organ system. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project--Cooperative Agreements (U01)
Project #
5U01AI066335-02
Application #
7124733
Study Section
Special Emphasis Panel (ZAI1-MP-I (M1))
Program Officer
Koh, Crystal Y
Project Start
2005-09-30
Project End
2010-02-28
Budget Start
2006-03-01
Budget End
2007-02-28
Support Year
2
Fiscal Year
2006
Total Cost
$447,445
Indirect Cost
Name
University of Maryland Baltimore
Department
Surgery
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Harris, Donald G; Quinn, Kevin J; French, Beth M et al. (2015) Meta-analysis of the independent and cumulative effects of multiple genetic modifications on pig lung xenograft performance during ex vivo perfusion with human blood. Xenotransplantation 22:102-11
Azimzadeh, Agnes M; Kelishadi, Sean S; Ezzelarab, Mohamed B et al. (2015) Early graft failure of GalTKO pig organs in baboons is reduced by expression of a human complement pathway-regulatory protein. Xenotransplantation 22:310-6
Azimzadeh, Agnes M; Byrne, Guerard W; Ezzelarab, Mohamed et al. (2014) Development of a consensus protocol to quantify primate anti-non-Gal xenoreactive antibodies using pig aortic endothelial cells. Xenotransplantation 21:555-66
LaMattina, John C; Burdorf, Lars; Zhang, Tianshu et al. (2014) Pig-to-baboon liver xenoperfusion utilizing GalTKO.hCD46 pigs and glycoprotein Ib blockade. Xenotransplantation 21:274-86
Burdorf, L; Stoddard, T; Zhang, T et al. (2014) Expression of human CD46 modulates inflammation associated with GalTKO lung xenograft injury. Am J Transplant 14:1084-95
Nguyen, Bao-Ngoc H; Azimzadeh, Agnes M; Schroeder, Carsten et al. (2011) Absence of Gal epitope prolongs survival of swine lungs in an ex vivo model of hyperacute rejection. Xenotransplantation 18:94-107
Chan, Siaw-Lin; Voskens, Caroline J; Lin, Wei et al. (2009) Epitope mapping of a chimeric CD137 mAb: a necessary step for assessing the biologic relevance of non-human primate models. J Mol Recognit 22:242-9
Pierson 3rd, Richard N; Dorling, Anthony; Ayares, David et al. (2009) Current status of xenotransplantation and prospects for clinical application. Xenotransplantation 16:263-80
Ezzelarab, Mohamed; Garcia, Bertha; Azimzadeh, Agnes et al. (2009) The innate immune response and activation of coagulation in alpha1,3-galactosyltransferase gene-knockout xenograft recipients. Transplantation 87:805-12
Pierson 3rd, Richard N (2009) Antibody-mediated xenograft injury: mechanisms and protective strategies. Transpl Immunol 21:65-9

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