Metabolic preconditioning of donor organs: Defatting fatty livers by normothermic perfusion ex vivo

Abstract

Fatty liver is a significant risk factor for liver transplantation, and accounts for nearly half of the livers rejected from the donor pool. We hypothesized that metabolic preconditioning via ex vivo perfusion of the liver graft can reduce fat content and increase post-transplant survival to an acceptable range. We describe a perfusate medium containing agents that promote the defatting of hepatocytes and explanted livers. Defatting agents were screened on cultured hepatocytes made fatty by pre-incubation with fatty acids. The most effective agents were then used on fatty livers. Fatty livers were isolated from obese Zucker rats and normothermically perfused with medium containing a combination of defatting agents. This combination decreased the intracellular lipid content of cultured hepatocytes by 35% over 24 hours, and of perfused livers by 50% over 3 hours. Metabolite analysis suggests that the defatting cocktail upregulated both lipid oxidation and export. Furthermore, gene expression analysis for several enzymes and transcription factors involved in fatty acid oxidation and triglyceride clearance were elevated. We conclude that a cocktail of defatting agents can be used to rapidly clear excess lipid storage in fatty livers, thus providing a new means to recondition donor livers deemed unacceptable or marginally acceptable for transplantation. Keywords nuclear receptors; normothermic perfusion; hepatocytes; steatosis; liver transplantation Orthotopic liver transplantation (OLT) is a highly successful therapeutic modality for the treatment of end-stage liver disease. The main limitation of OLT is the scarcity of donor livers. Currently, the majority of donor livers are obtained from cadavers with irreversible loss of brain function who still have functioning circulation and respiration. Among such donors, the most common single predisposing significant risk factor for postoperative liver failure is increased fat content (also called steatosis) of the liver (Canelo et al., 1999;Strasberg et al., 1994). Steatosis accounts for nearly half of the livers rejected from the donor pool (Chan et al., 2004). Thus, salvaging these steatotic donor livers that would be otherwise discarded may significantly expand the donor pool and help close the gap between supply and demand in liver transplantation. While there are many reports focusing on protecting the fatty donor liver from Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. (Belghiti et al., 1999;Nakamuta et al., 2005;Tanaka et al., 1990), so far none of these approaches have been successfully applied to clinical practi...

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