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Celsior, a low viscosity and low potassium preservation solution, has recently been tested successfully in the cold preservation of heart, lung, kidney and small intestine. The purpose of the present study was to evaluate the potential of Celsior in the cold preservation of the liver. Livers were harvested from male Wistar rats and then flushed with either Celsior (CE), University of Wisconsin solution (UW) or histidine-tryptophan-α-ketoglutarate solution (HTK) and stored for 24 h at 4°C in the respective solution. The reperfusion was performed in vitro using a recirculating model with oxygenated (95% O₂, 5% CO₂) Krebs-Henseleit buffer at 37°C. To simulate the slow rewarming during the surgical implantation in vivo, all livers were stored for 30 min at room temperature prior to reperfusion. After ischemic storage and also after reperfusion some samples were freeze-clamped for analysis of tissue metabolites while others were tested for structural and functional integrity by the isolated perfusion. CE vs. UW vs. HTK: Metabolic preservation of tissue ATP (μmol/g dry weight) during cold storage was best with Celsior (0.46 ± 0.17 vs. 0.26 ± 0.03 vs. 0.35 ± 0.07; p < 0.05 CE vs. UW), but upon reperfusion energetic recovery was comparable in the three groups (3.45 ± 0.66 vs. 4.27 ± 0.41 vs. 3.63 ± 0.64 μmol/g/dry weight). There appeared to be structural integrity during reoxygenation irrespective of the used preservation solution with comparable values of parenchymal enzyme release (ALT: 575 ± 82 vs. 547 ± 106 vs. 593 ± 38 mU/g/l), bile production (18.0 ± 1.0 vs. 18.5 ± 2.5 vs. 18.7 ± 1.4 μl/g/ min), and the release of acid phosphatase, an indicator for activated Kupffer cells (89 ± 13 vs. 90 ± 5 vs. 123 ± 21 mU/g/l) in this in vitro model. Vascular flow characteristics were approximated by the portal perfusion pressure, which tended to be elevated upon initial reperfusion in the UW group (8.4 ± 0.6 mm Hg) compared to 6.6 ± 1.0 and 7.3 ± 0.4 mm Hg in Celsior and HTK, respectively. However, the pressure values decreased to the normal range even in the UW group with ongoing perfusion. The sensitivity of our model in detecting protective effects of the tested solution was confirmed by a negative control group of livers stored in Ringer’s solution at 4°C, yielding an impaired recovery which differed by one magnitude from the three other groups. Within the limits of an in vitro study it is concluded from these results that Celsior may become a suitable alternative for liver preservation and further studies including a transplantation in vivo are strongly encouraged.

The aim of the present study was to improve the viability of marginal livers from non-heart beating donors upon cold preservation using two different techniques for the provision of tissue aerobiosis. Livers from male Wistar rats (250-300 g bw) were harvested after 60 min of cardiac arrest, flushed via the portal vein with 20 mL of heparinized Ringer's solution and 60 mL of histidine-tryptophan-ketoglutarate (HTK) preservation solution. Control livers were then stored submerged in HTK for 24 h at 4 degrees C while other organs were subjected to aerobic conditions by either insufflation of gaseous oxygen via the venous vascular system of the cold stored organ (VSOP) or pulsatile machine perfusion (MP) with oxygenated HTK at 5 mL/min at 4 degrees C. Superoxide dismutase (SOD) (7500 IU) was added to the last 10 mL of HTK in order to prevent adverse effects of high oxygen tensions at hypothermia. Viability of the livers was assessed upon isolated perfusion in vitro with oxygenated Krebs-Henseleit buffer at constant flow. VSOP or MP, both significantly improved vascular conductivity upon reperfusion as evaluated by portal venous pressure, reduced hepatic enzyme release and led to a rise in hepatic bile production upon reperfusion. Induction of apoptosis was also looked for in tissue homogenates by Western analysis for cleavage of poly(ADP-ribose)polymerase (PARP). Expression of cleaved PARP fragment could be found in reperfused control livers but also, though to a lesser extend, after VSOP or MP. In conclusion, provision of oxygen during cold preservation significantly contributes to improve organ viability upon reperfusion and must be regarded as a useful adjunct for marginal or pre-damaged livers. HTK has been shown for the first time to be also suitable for long-term MP preservation of the liver, but, as inferred from these data, simple insufflation of gaseous O2 may be considered a feasible alternative.

In this study, the importance of antioxidants during oxygenated liver preservation has been investigated. Livers were excised from rats after 60 min of cardiac arrest and stored for 24 h at 4 degrees C in University of Wisconsin solution (UW). Gaseous oxygen was applied to the livers during the storage period via the caval vein after superoxide dismutase (SOD, 600 U/mL), taurine (0.5 mg/mL), or no antioxidant was applied to the graft with the rinse solution. It was shown that oxygen persufflation significantly enhanced the viability of livers during cold preservation only in combination with SOD or taurine, which were both equally effective in reducing lipid peroxidation, enzyme release, and vascular resistance upon postischemic reperfusion. An increase in hepatic bile production was also observed.