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Physiologic barriers to xenotransplantation

Thein, E; Hammer, C

Current Opinion in Organ Transplantation: June 2004 - Volume 9 - Issue 2 - p 186-189
doi: 10.1097/01.mot.0000126087.48709.13
Xenotransplantation
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Purpose of review Physiologic compatibilities and incompatibilities between the donor and recipient species may present hurdles to successful xenotransplantation. The purpose of this review is to give an overview of findings in xenophysiology during the past 15 months.

Recent findings Several studies have shown that incompatibilities between the porcine and human physiologies may have a dramatic influence on a patient’s outcome after xenotransplantation. Species-specific properties induce systemic activation of the recipient’s coagulation system in various pathways, leading to disseminated intravascular coagulopathy. Porcine erythropoietin was shown to be unable to induce erythropoiesis in primates, but it will probably induce antibodies cross-reacting with endogenous and recombinant human erythropoietin, thus making the recipient of a xenotransplanted kidney transfusion dependent. Xenotransplantation of livers revealed that the liver will not, or at least not completely, adapt to its new environment. Consequently, the molecular structure and the serum concentration of the molecules synthesized by the liver will be physiologic for the organ donor but not for the recipient. This may lead to the breakdown of a variety of functional cascades, such as the complement system. Physiologic compatibility may cause problems as well. Recently two molecules on human cells have been identified to be receptors for the porcine endogenous retrovirus. These and other receptors may render human cells potentially susceptible to porcine microorganisms like porcine influenza viruses or herpesviruses.

Summary Species-specific physiologic properties will cause problems in xenotransplantation far beyond rejection. These problems remain and need to be solved before xenotransplantation becomes a clinical option.

Institute for Surgical Research, University of Munich, Munich, Germany

Correspondence to Eckart Thein, Institute for Surgical Research, Marchionini Str. 27, 81377 Munich, Germany

Tel: +49 89 7095 4404 Fax: +49 89 7095 4404;

e-mail: ethein@icf.med.uni-muenchen.de

© 2004 Lippincott Williams & Wilkins, Inc.