Expanding the Donor Pool in Liver Transplantation: Influence of Ischemia-Reperfusion

Improvements in surgical techniques, immunosuppression, and patient management have led to the optimization of liver transplantation outcomes. However, the waiting list for liver transplantation is increasing at a greater pace. The large imbalance between the growing pool of potential liver transplant recipients and the scarcity of donor organs has fueled efforts to maximize existing donors and identify new sources. To expand the potential donor pool, clinical, and organ procurement agencies are continually modifying the criteria of an acceptable liver donor and are looking to marginal or expanded donors to meet the waiting list demands. This book chapter will be focused on the current state of liver transplantation using grafts from extended criteria donors (elderly donors, steatotic donors, donors with malignancies, donors with viral hepatitis) and from donation after cardiac death (non-heart beating donors), as well as the use of partial grafts (split grafts and living-donor liver transplantation) and other suboptimal donors (donors with hypernatraemia, infections, hypotension and inotropic support). Overall, broadened criteria for acceptable donor livers appear to lessen graft survival rates somewhat compared with rates for ideal donor organs. Donors are generally considered marginal if there is a risk of initial poor function or primary non-function. The present book chapter will discuss the factors defining marginality of a graft, the pathophysiology of the marginal donor, and the issues faced by transplant units in making the decision to use such a graft; along with strategies for minimizing the ischemia-reperfusion injury experienced by the organs. We will show the * cperalta@clinic.ub. es. No part of this digital document may be reproduced, stored in a retrieval system or transmitted commercially in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in rendering legal, medical or any other professional services. M. B. Jiménez-Castro, M. Elias-Miró and C. Peralta 42 experimental models used to study the complexity of hepatic ischemia-reperfusion injury in marginal donors. Data reported in animal models and the different strengths and limitations of the different experimental models will be also discussed. This is a valuable tool for discovering novel therapeutic targets and drugs. New surgical and pharmacological strategies for improving the function of the marginal/expanded donor liver also will be reviewed. This would be of clinical interest to reduce their prevalence and improve their management. As we will discuss in the book chapter, at this time the management of marginal donors is empirical, being currently based on clinical practical experience. We will show that further experimental research is needed to identify better tests for evaluating donor organs, provide longer-term follow-up of recipients of higherrisk organs, and develop alternative means to fill the donor-organ shortfall.