Usefulness of preservation by machine perfusion of liver grafts from non-heart-beating donors-a porcine model

Hypothermic oxygenated perfusion with defatting cocktail further improves steatotic liver grafts in a transplantation rat model

In this study, we evaluated the restoring and defatting effect of hypothermic oxygenated perfusion (HOPE) on severe steatotic liver grafts with a defatting cocktail (DF) in a rat model. Severe (≥60%) hepatic macrosteatosis was induced by a high-fat diet (HFD) for 6 weeks, after which the rats were randomly divided into four following groups: Control group, with lean livers being preserved in static cold storage (SCS) at 0°C-4°C for 45 minutes; SCS group, with a steatotic liver graft (SLG) being preserved in SCS at 0°C-4°C for 4 hours; HOPE group, where SLG was perfused with 3-hours HOPE followed by 1-hours SCS; and HOPE + DF group, HOPE with the addition of DF. Graft function after orthotopic liver transplantation was assessed in terms of mitochondrial function (adenosine triphosphate [ATP], Glycogen), endoplasmic reticulum stress (PPY, GRP78, CHOP, and ATF-6), cell apoptosis (Tunel assay, Caspase-3), inflammatory level (HMGB1, TLR4, IL-1β, IL-6. TNF-α, Factor V), and posttransplantation survival. HOPE protected steatotic liver grafts from microcirculation disturbance and endoplasmic reticulum stress and then promoted ATP and glycogen synthesis that improved mitochondrial function. Meanwhile, under conditions of ischemia-reperfusion injury, it prevented nuclear injury and endothelial damage by suppressing the release of an inflammatory mediator. The high efficacy of HOPE was enhanced after the addition of the DF. DF agents cannot promote the lipid decomposition of the steatotic liver graft at 0°C-4°C, but they can further improve steatotic liver and postoperative survival compared to the HOPE. The defatted steatotic liver grafts can be safely used in rat orthotopic liver transplantation.

Current review of machine perfusion in liver transplantation from the Japanese perspective

In light of the present evidence, machine perfusion is opening up new horizons in the field of liver transplantation. Although many advances have been made in liver transplantation, organ preservation methods have so far changed very little. Static cold storage is universally used for graft preservation in liver transplantation; however, there is a need for better preservation methods, such as ex vivo machine perfusion, to improve the outcomes by decreasing warm ischemic damage. Based on the findings of basic and clinical trials, hypothermic and normothermic machine perfusion techniques are now commercially available and include the OrganOx metra, Liver Assist, Cleveland NMP device, Organ Care System, and LifePort Liver. Recent clinical trials have provided further evidence for the potential role of normothermic machine perfusion to resuscitate and subsequently improve utilization of marginal or currently discarded livers. Further studies are required to explore the longer-term outcomes, late biliary complications, outcomes in specific high-risk groups, viability biomarkers, optimum and maximum perfusion duration, perfusate composition, and liver-directed therapeutic interventions during normothermic machine perfusion. The use of organs from marginal donors after brain death, such as fatty livers and the livers from elderly donors with multiple comorbidities, may be accepted for machine perfusion in Japan in the near future.

Machine Perfusion of Donor Livers for Transplantation: A Proposal for Standardized Nomenclature and Reporting Guidelines

With increasing demand for donor organs for transplantation, machine perfusion (MP) promises to be a beneficial alternative preservation method for donor livers, particularly those considered to be of suboptimal quality, also known as extended criteria donor livers. Over the last decade, numerous studies researching MP of donor livers have been published and incredible advances have been made in both experimental and clinical research in this area. With numerous research groups working on MP, various techniques are being explored, often applying different nomenclature. The objective of this review is to catalog the differences observed in the nomenclature used in the current literature to denote various MP techniques and the manner in which methodology is reported. From this analysis, we propose a standardization of nomenclature on liver MP to maximize consistency and to enable reliable comparison and meta-analyses of studies. In addition, we propose a standardized set of guidelines for reporting the methodology of future studies on liver MP that will facilitate comparison as well as clinical implementation of liver MP procedures.

Challenges and advances in optimizing liver allografts from donation after circulatory death donors

In recent years, there has been a shift in the donor demographics with an increase in donation after circulatory death (DCD). Livers obtained from DCD donors are known to have poorer outcomes when compared to donors after brainstem death and currently only a small proportion of DCD livers are used. This review outlines the recent technological developments in liver DCD donation, including clinical studies using normothermic regional perfusion and extracorporal machine perfusion of livers from DCD donors.

"Resuscitation" of marginal liver allografts for transplantation with machine perfusion technology

As the rate of medically suitable donors remains relatively static worldwide, clinicians have looked to novel methods to meet the ever-growing demand of the liver transplant waiting lists worldwide. Accordingly, the transplant community has explored many strategies to offset this deficit. Advances in technology that target the ex vivo "preservation" period may help increase the donor pool by augmenting the utilization and improving the outcomes of marginal livers. Novel ex vivo techniques such as hypothermic, normothermic, and subnormothermic machine perfusion may be useful to "resuscitate" marginal organs by reducing ischemia/reperfusion injury. Moreover, other preservation techniques such as oxygen persufflation are explored as they may also have a role in improving function of "marginal" liver allografts. Currently, marginal livers are frequently discarded or can relegate the patient to early allograft dysfunction and primary non-function. Bench to bedside advances are rapidly emerging and hold promise for expanding liver transplantation access and improving outcomes.

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.

Wash-out of the non-heart-beating donor liver: a matter of flush solution and temperature?

BACKGROUND AND AIMS

Ischemically damaged donor livers are prone to graft non-function. This can in part be explained by a suboptimal wash-out during procurement. An enriched machine perfusion (MP) preservation solution for livers, named Polysol, was developed. The aim of this study was to investigate the type of flush solution, temperature and anticoagulant content on the wash-out of the non-heart-beating donor (NHBD) rat liver.

METHODS

Rat livers were flushed after 30 min warm ischemia. After excision, livers were reperfused at 37 degrees C, with analysis of damage and function, concerning (1) solutions (University of Wisconsin (UW), histidine-tryptophan-ketoglutarate (HTK) and Polysol); (2) temperature (4 degrees C, 18 degrees C and 37 degrees C); (3) addition of heparin and (4) wash-out followed by 24 h MP.

RESULTS

(1) Reperfusion results were inferior in the UW group; (2) less damage and improved function were seen after wash-out using Polysol at 37 degrees C; (3) No effects were seen of the addition of heparin to Polysol; (4) MP after wash-out using HTK resulted in more liver damage and decreased liver function as compared with wash-out using Polysol.

CONCLUSIONS

Polysol is applicable as a flush solution for the NHBD liver, resulting in equal to better wash-out as compared with UW and HTK. The best temperature for this NHBD wash-out is 37 degrees C.

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 degrees 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.

Strategies to prevent chronic allograft nephropathy in kidney transplantation: focus on calcineurin inhibitors

Chronic allograft nephropathy is one of the leading causes of long-term graft failure in kidney transplant recipients. The etiology of this condition is multifactorial, but administration of calcineurin inhibitors is often implicated. With the introduction of newer immunosuppressive agents, strategies for calcineurin inhibitor minimization, avoidance, and withdrawal have been emerging in the literature. These strategies may improve long-term kidney allograft function, but are not without risks. Results from recent clinical trials evaluating the safety and efficacy of these strategies to prevent chronic allograft nephropathy in kidney transplant recipients are summarized and reviewed. Patients who had never received a calcineurin inhibitor or who had cyclosporine withdrawn from their regimens had better kidney function than patients who received or kept receiving a calcineurin inhibitor. The impact of the improvement in kidney function on long-term graft survival remains to be determined. In addition, the benefit in renal function must be weighed against the bone marrow toxicities and/or metabolic complications associated with these regimens.

PRONLONGED HYPOTHERMIC MACHINE PERFUSION PRESERVES HEPATOCELLULAR FUNCTION BUT POTENTIATES ENDOTHELIAL CELL DYSFUNCTION IN RAT LIVERS

BACKGROUND

Although hypothermic machine perfusion (HMP) preservation has been shown to improve organ function and to expand the organ donor pool, problems still exist with the current HMP technology for liver preservation. The present study was conducted to investigate endothelial and hepatocellular functions following extended HMP (> r =24 hr) in rat liver model.

METHODS

Following 24-hour hypothermic HMP with University of Wisconsin (UW) solution or 24-hour simple cold storage (SCS), livers were reperfused with Krebs-Henseleit buffer solution at 37 degree C for 30 minutes. Hepatocyte damage and function were assessed by measuring lactate dehydrogenase (LDH) activity, bile production, and indocyanine green (ICG) extraction. Sinusoidal endothelial cell (SEC) function and permeability were determined by hyaluronic acid (HA) uptake and multiple indicator dilution (MID) method, respectively.

RESULTS

After 24-hour hypothermic preservation, HMP livers showed lower released LDH levels, higher bile flow rate, and greater hepatic ICG uptake compared with SCS livers. However, LDH levels became significantly higher in HMP than in SCS after 30 minutes of warm perfusion. The increased enzyme levels were accompanied by a significant increase in endothelial permeability to albumin and a decrease in hyaluronic acid uptake in HMP compared to SCS. Liver wet/dry weight ratio confirmed a greater edema in HMP livers than SCS livers.

CONCLUSION

These results suggest that 24-hour hypothermic HMP may help preservation of hepatocyte function, but endothelial cell dysfunction during the cold preservation may play a key role in hepatocyte dysfunction and parenchymal cell death upon reperfusion.