B M. Doorschodt

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.

Improved rat liver preservation by hypothermic continuous machine perfusion using polysol, a new, enriched preservation solution

For experimental machine perfusion (MP) of the liver, the modified University of Wisconsin solution (UW‐G) is most often used. In our search for an enriched MP preservation solution, Polysol was developed. Polysol is enriched with various amino acids, vitamins, and other nutrients for the liver metabolism. The aim of this study was to compare Polysol with UW‐G for MP preservation of the liver. Rat livers were preserved during 24 hours with hypothermic MP using UW‐G (n = 5) or Polysol (n = 5). Hepatocellular damage (aspartate aminotransferase [AST], alanine aminotransferase [ALT], lactate dehydrogenase [LDH], alpha‐glutathione‐S‐transferase [alpha‐GST]) and bile production were measured during 60 minutes of reperfusion (37°C) with Krebs‐Henseleit buffer. Control livers were reperfused after 24 hours of cold storage in UW (n = 5). MP using UW‐G or Polysol showed less liver damage when compared with controls. Livers machine perfused with Polysol showed less enzyme release when compared to UW‐G. Bile production was higher after MP using either UW‐G or Polysol compared with controls. In conclusion, machine perfusion using Polysol results in better quality liver preservation than cold storage with UW and machine perfusion using UW‐G. (Liver Transpl 2005;11:539–546.)

Pulsatile perfusion preservation of warm ischaemia-damaged experimental kidney grafts

Cold storage using histidine–tryptophan–ketoglutarate (HTK) solution is used widely in clinical practice for the preservation of warm ischaemia‐damaged kidney grafts. This study assessed the efficacy of pulsatile machine perfusion in combination with Polysol® for the preservation of warm ischaemia‐damaged kidney grafts.

Improved Renal Function of Warm Ischemically Damaged Kidneys Using Polysol

OBJECTIVE We sought to assess the efficacy of POLYSOL, a low-viscosity, colloid-based organ preservation solution, for the preservation of warm ischemically damaged kidney grafts compared with histidine-tryptophane-ketoglutarate (HTK) solution. METHODS Pigs (25-30 kg) underwent a left nephrectomy after clamping the renal vessels for 30 minutes. Kidney grafts washed out with Polysol (n = 6) or HTK (n = 6) were cold stored (CS) for 20 hours at 4 degrees C. After the preservation period, the contralateral kidney was removed and the preserved kidney implanted heterotopically. Renal function was assessed daily for 7 days. Thereafter, animals were killed and the kidney grafts removed for histologic analysis. RESULTS All animals survived for 7 days. All Polysol CS-preserved grafts showed immediate function, as demonstrated by urine production within 24 hours after reperfusion as compared with 3/6 grafts in the HTK CS group. Overall, the Polysol CS group showed improved renal function compared with HTK CS. Also, peak serum creatinine and blood urea values were lower in the Polysol CS group compared with HTK-preserved grafts. Histologic evaluation of warm ischemically damaged grafts showed less glomerular shrinking, less tubular damage, less edema, less inflammatory infiltration, and less necrosis in Polysol compared with HTK-preserved grafts. CONCLUSION Application of Polysol solution for washout and CS preservation of warm ischemically damaged kidney grafts resulted in improved renal function and structural integrity when compared with HTK.

First Clinical Experience With Polysol Solution: Pilot Study in Living Kidney Transplantation

In this study, we assessed the safety of the new organ preservation solution polysol solution in the clinical setting of living kidney transplantation. We conducted a prospective pilot study in nine adult donor-recipient couples using polysol solution for washout and cold storage of kidney grafts. Adverse reactions possibly related to the use of polysol solution as well as renal function at 1, 6, and 12 months after transplantation were monitored. All living kidney transplantation performed in adults in our center within 2002 to 2008 using the University of Winconsin solution served as controls (n = 190). The use of polysol solution was associated with a higher acute rejection rate compared to University of Wisconsin solution at all time points. Also, antibody-mediated rejection occurred more frequently in the polysol group. Renal function at all time points was also comparable between the groups. This pilot study in living kidney transplantation is the first clinical study on the use of polysol solution. Although the study was not powered on the endpoint rejection, we observed a high number of acute rejection and antibody-mediated rejection episodes in recipients of polysol solution preserved grafts as compared to University of Wisconsin solution controls. As a consequence the study was terminated prematurely.

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.