Maud Bessems

The isolated perfused rat liver: standardization of a time-honoured model

For many years, the isolated perfused rat liver (IPRL) model has been used to investigate the physiology and pathophysiology of the rat liver. This in vitro model provides the opportunity to assess cellular injury and liver function in an isolated setting. This review offers an update of recent developments regarding the IPRL set-up as well as the viability parameters that are used, with regards to liver preservation and ischaemia and reperfusion mechanisms. A review of the literature was performed into studies regarding liver preservation or liver ischaemia and reperfusion. An overview of the literature is given with particular emphasis on perfusate type and volume, reperfusion pressure, flow, temperature, duration of perfusion, oxygenation and on applicable viability parameters (liver damage and function). The choice of IPRL set-up depends on the question examined and on the parameters of interest. A standard technique is cannulation of the portal vein, bile duct and caval vein with pressure-controlled perfusion at 20 cm H2O (15 mmHg) to reach a perfusion flow of approximately 3 mL/min/g liver weight. The preferred perfusion solution is Krebs–Henseleit buffer, without albumin. The usual volume is 150–300 cm3, oxygenated to a pO2 of more than 500 mmHg. The temperature of the perfusate is maintained at 37°C. Standardized markers should be used to allow comparison with other experiments.

Preservation of steatotic livers : A comparison between cold storage and machine perfusion preservation

Liver grafts are frequently discarded due to steatosis. Steatotic livers can be classified as suboptimal and deteriorate rapidly during hypothermic static preservation, often resulting in graft nonfunction. Hypothermic machine perfusion (MP) has been introduced for preservation of donor livers instead of cold storage (CS), resulting in superior preservation outcomes. The aim of this study was to compare CS and MP for preservation of the steatotic donor rat liver. Liver steatosis was induced in male Wistar rats by a choline‐methionine‐deficient diet. After 24 hours hypothermic CS using the University of Wisconsin solution (UW) or MP using UW‐Gluconate (UW‐G), liver damage (liver enzymes, perfusate flow, and hyaluronic acid clearance) and liver function (bile production, ammonia clearance, urea production, oxygen consumption, adenosine triphosphate [ATP] levels) were assessed in an isolated perfused rat liver model. Furthermore, liver biopsies were visualized by hematoxylin and eosin staining. Animals developed 30 to 60% steatosis. Livers preserved by CS sustained significantly more damage as compared to MP. Bile production, ammonia clearance, urea production, oxygen consumption, and ATP levels were significantly higher after MP as compared to CS. These results were confirmed by histology. In conclusion, MP improves preservation results of the steatotic rat liver, as compared to CS. Liver Transpl 13:497–504, 2007.

Improved machine perfusion preservation of the non‐heart‐beating donor rat liver using polysol: A new machine perfusion preservation solution

Waiting lists for transplantation have stimulated interest in the use of non‐heart‐beating donor (NHBD) organs. Recent studies on organ preservation have shown advantages of machine perfusion (MP) over cold storage (CS). To supply the liver with specific nutrients during MP, the preservation solution Polysol was developed. The aim of our study was to compare CS in University of Wisconsin solution (UW) with MP using UW‐gluconate (UW‐G) or Polysol in an NHBD model. After 30 minutes of warm ischemia, livers were harvested from rats for preservation by either CS, MP‐UW‐G, or MP‐Polysol. After 24 hours of preservation, livers were reperfused with Krebs‐Henseleit buffer (KHB). Perfusate samples were analyzed for liver damage and function. Biopsies were examined by hematoxylin and eosin staining and transmission electron microscopy. Liver damage was highest after CS compared with the MP groups. MP using Polysol compared with UW‐G resulted in less aspartate aminotransferase (AST) and alanine aminotransferase (ALT) release. Perfusate flow, bile production, and ammonia clearance were highest after MP‐Polysol compared with CS and MP‐UW‐G. Tissue edema was least after MP‐Polysol compared with CS and MP‐UW‐G. In conclusion, preservation of the NHBD rat liver by hypothermic MP is superior to CS. Furthermore, MP using Polysol results in better‐quality liver preservation compared with using UW‐G. (Liver Transpl 2005;11:1379–1388.)

WASH-OUT OF THE NON-HEART-BEATING DONOR LIVER: A COMPARISON BETWEEN RINGERS LACTATE, HTK AND POLYSOL

UNLABELLED The solution of choice for wash-out of non-heart-beating donor (NHBD) livers is histidine tryptophan ketoglutarate (HTK). This solution has a lower viscosity, due to absence of a colloid, and is less expensive as compared to the University of Wisconsin (UW) solution. A new preservation solution for machine perfusion was developed, named Polysol. In order to apply Polysol clinically in NHBD organ retrieval, the efficacy as a wash-out solution was investigated. METHODS After a warm ischemic time of 30 minutes, the rat liver was washed out via the portal vein with 50 mL of either ringer lactate (RL), HTK or Polysol. After wash-out and harvesting, the liver was reperfused with Krebs-Henseleit buffer. Samples were taken to assess hepatocellular injury and liver function. RESULTS Liver damage parameters were elevated in the RL group as compared to the HTK and Polysol groups. Liver/rat weight ratios were significantly lower after wash-out with Polysol. Overall, no differences were seen in ammonia clearance and bile production. In conclusion, wash-out of the NHBD liver with Polysol results in equal to improved reperfusion results as compared to HTK. Polysol is feasible as a wash-out solution in combination with machine perfusion using Polysol.