The influence of storage temperature during machine perfusion on preservation quality of marginal donor livers.

BACKGROUND: Although non-heart-beating donors have the potential to increase the number of available organs, the livers are used very seldom because of the risk of primary non-function. There is evidence that machine perfusion is able to improve the preservation of marginal organs, and therefore we evaluated in our study the influence of the perfusate temperature during oxygenated machine perfusion on the graft quality. METHODS: Livers from male Wistar rats were harvested after 60-min warm ischemia induced by cardiac arrest. The portal vein was cannulated and the liver flushed with Lifor (Lifeblood Medical, Inc.) organ preservation solution for oxygenated machine perfusion (MP) at 4, 12 or 21 degrees C. Other livers were flushed with HTK and stored at 4 degrees C by conventional cold storage (4 degrees C-CS). Furthermore two groups with either warm ischemic damage only or without any ischemic damage serve as control groups. After 6h of either machine perfusion or cold storage all livers were normothermic reperfused with Krebs-Henseleit buffer, and functional as well as structural data were analyzed. RESULTS: Contrary to livers stored by static cold storage, machine perfused livers showed independently of the perfusate temperature a significantly decreased enzyme release of hepatic transaminases (ALT) during isolated reperfusion. Increasing the machine perfusion temperature to 21 degrees C resulted in a marked reduction of portal venous resistance and an increased bile production. CONCLUSIONS: Oxygenated machine perfusion improves viability of livers after prolonged warm ischemic damage. Elevated perfusion temperature of 21 degrees C reconstitutes the hepatic functional capacity better than perfusion at 4 or 12 degrees C.

Erythropoietin reduces ischemia-reperfusion injury after liver transplantation in rats.

Human recombinant Erythropoietin (rHuEpo) has recently been shown to be a potent protector of ischemia- reperfusion injury in warm-liver ischemia. Significant enhancement of hepatic regeneration and survival after large volume partial hepatic resection has also been demonstrated. It was the aim of this study to evaluate the capacities of rHuEpo in the setting of rat liver transplantation. One-hundred-and-twenty Wistar rats were used: 60 recipients received liver transplantation following donor organ treatment (60 donors) with either 1000 IU rHuEpo or saline injection (controls) into portal veins (cold ischemia 18 h, University of Wisconsin (UW) solution). Recipients were allocated to two groups, which either received 1000 IU rHuEpo at reperfusion or an equal amount of saline (control). Animals were sacrificed at defined time-points (2, 4.5, 24, 48 h and 7 days postoperatively) for analysis of liver enzymes, histology [hematoxylin-eosin (HE) staining, periodic acid Schiff staining (PAS)], immunostaining [terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), Hypoxyprobe] and real-time polymerase chain reaction (RT-PCR) of cytokine mRNA (IL-1, IL-6). Lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) values were significantly reduced among the epo-treated animals 24 and 48 h after liver transplantation (LT). The TUNEL and Hypoxyprobe analyses as well as necrotic index evaluation displayed significant reduction of apoptosis and necrosis in rHuEpo-treated graft livers. Erythropoietin reduces ischemia-reperfusion injury after orthotopic liver transplantation in rats.

Improved microcirculation by low-viscosity histidine- tryptophan-ketoglutarate graft flush and subsequent cold storage in University of Wisconsin solution: results of an orthotopic rat liver transplantation model.

As previously shown in a model of isolated rat liver perfusion, the combined use of an initial graft flush with low-viscosity histidine-tryptophan-ketoglutarate (HTK) solution followed by cold storage in University of Wisconsin (UW) solution markedly improved the preservation during an extended cold storage period. In this study, we aimed to transfer our results into an in vivo model of orthotopic rat liver transplantation, and to elucidate the potential mechanism of the improved preservation by focusing on the hepatic microcirculation. Livers were harvested from male Wistar rats. Aortic perfusion with a pressure of 100 cm H(2)O was performed with either UW (group UW) or HTK (groups UW and HTK_UW), followed by additional back-table perfusion with UW (group HTK_UW). After 20-h cold storage at 4 degrees C, livers were orthotopically transplanted with reconstructing the hepatic artery. As measured by bile flow and liver enzymes, HTK flush followed by UW storage was superior compared to single use of either UW or HTK solution. The hepatic microcirculation was significantly improved, as shown by the increased percentage of reperfused sinusoids and reduced sinusoidal leucostasis. HTK and UW effectively reduce ischaemia-reperfusion injury after liver transplantation. By combining the comparative advantages of both solutions, a cumulative effect resulting in an improved preservation was shown. Thus, this mechanism improves microcirculatory reperfusion.

Low viscosity histidine-tryptophan-ketoglutarate graft flush improves subsequent extended cold storage in University of Wisconsin solution in an extracorporeal rat liver perfusion and rat liver transplantation model.

Adequate flushing for liver donation requires large fluid volumes delivered at a high flow. This can be achieved more effectively with crystalloid solutions than with colloid-based solutions. This study examined the combination of initial histidine-tryptophan-ketoglutarate solution (HTK) graft flush and subsequent storage in University of Wisconsin solution (UW) to that of the single use of each solution. Livers from inbred Wistar rats were procured using aortic perfusion with UW or HTK for initial perfusion and reflushed after 30 minutes using either solution. In a third group, after perfusion with HTK, organs were reflushed with UW. A 60-minute in-vitro recirculating perfusion was performed after 24 hours of cold storage in the subsequent solution, as well as allotransplantation after 18 and 24 hours of cold storage. In extracorporeal perfusion, the HTK flush followed by UW storage was superior compared to the single use of either UW or HTK solution, as measured by portal venous pressure, bile flow, liver enzymes released into the effluent perfusate, glycerol leakage, and histological examinations. These data were consistent with the transplantation study. Histological damage and enzyme release after 5-day survival were lowest in the HTK flush and subsequent UW storage groups following 18 hours of cold storage; likewise, the 5-day survival was superior following 24 hours of cold storage. In conclusion, the combined use of HTK solution for initial graft rinse and subsequent storage in UW solution resulted in a cumulative protection. Choosing low-viscosity HTK solution for the initial organ flush may represent a feasible improvement in liver preservation, which also further reduces the required amount of UW solution.