Improved Assessment of Graft Function by Echocardiography in Cynomolgus Monkey Recipients of hDAF-Transgenic Pig Cardiac Xenografts Mario Stalder, MD, a Terry Tye, MS, a Tuan T. Lam, MD, a Michael C. Y. Chan, MD, b Gerald J. Berry, MD, c Dominic C. Borie, MD, PhD, a and Randall E. Morris, MD a Background: The current practice of evaluating heterotopic heart xenografts by palpation allows only detection of severe graft dysfunction, which indicates terminal graft failure. Therefore, we evaluated whether echocardiography is a better method of detecting early graft dysfunction as a marker of rejection in abdominal pig heart xenografts in cynomolgus monkeys. Methods: Six cynomolgus monkeys received heterotopic heart transplants from pig donors transgenic for human decay-accelerating factor (hDAF). Induction therapy consisted of either cyclophosphamide or rabbit anti-thymocyte globulin. Maintenance therapy consisted of cyclosporine or tacrolimus, steroids, and sodium mycophenolate or mycophenolate mofetil, GAS914 (Gal oligosaccharide containing glycoconjugate), and for some animals TP10 (soluble complement receptor type 1). Echocardiography was performed immediately after transplantation and 3 times a week after surgery. We scored contractility and measured left ventricular wall thickness. Impaired contractility or increased wall thickness were considered graft dysfunction and were treated with pulse steroids. Palpation score was recorded daily. We also obtained myocardial biopsy specimens. Results: Palpation score remained at 4 out of 4 in all animals until 2 to 5 days before final graft failure, whereas echocardiography detected several episodes of impaired graft function, either decreased left ventricular contractility or increased left ventricular wall thickness before graft failure. Treatment with pulse steroids improved graft function only during early episodes of graft impairment. Final graft failure was steroid resistant and caused by severe vascular rejection. Conclusions: Echocardiography is a better method of assessing graft dysfunction than is palpation. Therefore, echocardiography may detect early rejection episodes of heterotopic heart xenografts in non-human primates. J Heart Lung Transplant 2005;24:215–21. Copyright © 2005 by the International Society for Heart and Lung Transplantation. Before xenotransplantation can be introduced into the clinical arena, newly developed therapies have to be evaluated in animal species that are closely related to humans. A common procedure is pig-to–non-human- primate heart transplantation, either in the heterotopic or the orthotopic position. 1,2 Heterotopic heart trans- plantation offers advantages over the orthotopic tech- nique because it is easier to perform and graft explan- tation with animal survival is possible. A recent study suggests that there are no differences in the pattern of injury during rejection between these 2 types of trans- plantation. 3 The development of pigs transgenic for human decay-accelerating factor (hDAF) and other strat- egies, such as neutralization of anti-Gal antibodies with synthetic Gal oligosaccharides, 4 (Lam TT, manu- script in preparation), immunoadsorbtion, 5,6 and block- ing complement activation either by consumption of complement with cobra venom factor 7 or by using soluble complement receptor type 1, 8 have made it possible to overcome hyperacute rejection. Therefore, the survival of pig cardiac xenografts in primates can be prolonged from a few hours to weeks or even months. Therefore, careful longl-term monitoring of grafts is becoming important, and the routine methods of assess- ing heterotopic cardiac grafts such as palpation or electrocardiographic tracing may no longer be sensitive From the a Transplantation Immunology, Department of Cardiotho- racic Surgery, b Division of Cardiovascular Medicine, c Department of Pathology, Stanford University School of Medicine, Stanford, Califor- nia. Submitted June 24, 2003; revised September 6, 2003; accepted September 16, 2003. Supported by the Ralph and Marian Falk Medical Trust, the HEDCO Foundation and Novartis Pharma AG (Basel, Switzerland). Dr. Stalder also was supported by the Foundation for Research in Cardiac Surgery, University Hospital Berne, Switzerland. Reprint requests: Randall E. Morris, M.D., Novartis Pharma AG, Corporate Headquarters WSJ 386.610, CH-4002 Basel, Switzerland. Telephone: 011-41-61-324-4713. Fax: 011-41-61-324-3537. E-mail: randall.morris@pharma.novartis.com Copyright © 2005 by the International Society for Heart and Lung Transplantation. 1053-2498/05/$–see front matter. doi:10.1016/ j.healun.2003.09.041 215 XENOTRANSPLANTATION