Liver preservation: is there anything new yet? Curr Opin Organ Transplant. 2008;13:148-154. [PMID: 18685295 DOI: 10.1097/mot.0b013e3282f63930]

Therapeutics administered during ex vivo liver machine perfusion: An overview

Although the use of extended criteria donors has increased the pool of available livers for transplant, it has also introduced the need to develop improved methods of protection against ischemia-reperfusion injury (IRI), as these "marginal" organs are particularly vulnerable to IRI during the process of procurement, preservation, surgery, and post-transplantation. In this review, we explore the current basic science research investigating therapeutics administered during ex vivo liver machine perfusion aimed at mitigating the effects of IRI in the liver transplantation process. These various categories of therapeutics are utilized during the perfusion process and include invoking the RNA interference pathway, utilizing defatting cocktails, and administering classes of agents such as vasodilators, anti-inflammatory drugs, human liver stem cell-derived extracellular vesicles, and δ-opioid agonists in order to reduce the damage of IRI. Ex vivo machine perfusion is an attractive alternative to static cold storage due to its ability to continuously perfuse the organ, effectively deliver substrates and oxygen required for cellular metabolism, therapeutically administer pharmacological or cytoprotective agents, and continuously monitor organ viability during perfusion. The use of administered therapeutics during machine liver perfusion has demonstrated promising results in basic science studies. While novel therapeutic approaches to combat IRI are being developed through basic science research, their use in clinical medicine and treatment in patients for liver transplantation has yet to be explored.

Hypothermic machine perfusion in liver transplantation

A finite supply of donor organs has led many transplant centers to accept marginal liver allografts with increasing frequency. These allografts may be at higher risk of primary nonfunction, early allograft dysfunction, and other recipient complications following liver transplantation. Machine perfusion preservation is an emerging technology that limits ischemia/reperfusion injury associated with preservation and may lead to improved outcomes following transplantation. Increased used of machine perfusion in liver preservation may permit an expansion of the donor pool. In this review, we examine the major clinical experience of hypothermic machine perfusion in human liver transplantation.Liver Transplantation 24 276-281 2018 AASLD.

Impact of Subnormothermic Machine Perfusion Preservation in Severely Steatotic Rat Livers: A Detailed Assessment in an Isolated Setting

The current drastic shortage of donor organs has led to acceptance of extended-criteria donors for transplantation, despite higher risk of primary nonfunction. Here, we report the impact of subnormothermic machine perfusion (SMP) preservation on the protection of >50% macrosteatotic livers. Dietary hepatic steatosis was induced in Wistar rats via 2-day fasting and subsequent 3-day re-feeding with a fat-free, carbohydrate-rich diet. This protocol induces 50-60% macrovesicular steatosis, which should be discarded when preserved via cold storage (CS). The fatty livers were retrieved and preserved for 4 h using either CS in histidine-tryptophan-ketoglutarate or SMP in polysol solution. Graft functional integrity was evaluated via oxygenated ex vivo reperfusion for 2 h at 37°C. SMP resulted in significant reductions in not only parenchymal alanine aminotransferase (p < 0.001), but also mitochondrial glutamate dehydrogenase (p < 0.001) enzyme release. Moreover, portal venous pressure (p = 0.047), tissue adenosine triphosphate (p = 0.001), bile production (p < 0.001), high-mobility group box protein-1 (p < 0.001), lipid peroxidation, and tissue glutathione were all significantly improved by SMP. Electron microscopy revealed that SMP alleviated deleterious alterations of sinusoidal microvasculature and hepatocellular mitochondria, both of which are characteristic disadvantages associated with steatosis. SMP could protect 50-60% macrosteatotic livers from preservation/reperfusion injury, and may thus represent a new means for expanding available donor pools.

Optimal Timing for Venous Systemic Oxygen Persufflation Supplemented with Nitric Oxide Gas in Cold-Stored, Warm Ischemia-Damaged Experimental Liver Grafts

Background/Aim: Worldwide shortage of donor organs has increased the use of donation after cardiac death (DCD). The aim of this study was to analyze the best time point for venous systemic oxygen persufflation (VSOP) supplemented with nitric oxide (NO) gas during the 1st and 24th hour of cold storage (CS) in warm ischemia (WI)-damaged experimental liver grafts. Materials and Methods: Liver grafts (n = 5) were retrieved after 30 min of WI induced by cardiac arrest and CS in histidine-tryptophan-ketoglutarate solution at 4°C. The 1st hour group was immediately persufflated with a VSOP plus NO (VSOP+NO) mixture for 1 h followed by 23 h of static CS (DCD+NO 1st hour). The 24th hour group entailed CS for 23 h followed by 1 h of VSOP+NO persufflation (DCD+NO 24th hour). CS livers without WI but with VSOP served as controls. CS livers with WI represented the fourth group (DCD). Viability of the liver grafts was assessed by normothermic isolated reperfusion for 45 min with oxygenated Krebs-Henseleit buffer. Results: Data are presented as mean ± SEM (control vs. DCD vs. DCD+NO 1st hour vs. DCD+NO 24th hour). After 45 min of reperfusion, the DCD+NO 1st hour group showed significantly lower aspartate aminotransferase (13.4 ± 5.3, 63.2 ± 17.3, 25.6 ± 3.9, and 82.8 ± 27.3 U/l) and lactate dehydrogenase levels (289.4 ± 41.2, 2,139.4 ± 542.7, 577.2 ± 117.2, and 2,429 ± 221.6 U/l). Malondialdehyde levels were significantly abrogated (1.0 ± 0.3, 2.7 ± 1, 1.0 ± 0, and 3.9 ± 1.2 nmol/ml). Significantly higher levels of portal venous pressure were recorded in the DCD+NO 24th hour group (12.0 ± 1, 21.2 ± 3.1, 16.1 ± 1, and 23.2 ± 3.5 mm Hg). NO levels were recorded after 5 min of reperfusion (1.42 ± 0.17, 1.8 ± 0.2, 2.7 ± 0.2, and 2.6 ± 0.1 μmol/l). Bile production levels showed no statistical significance (23.2 ± 3.8, 27.3 ± 1.8, 43.5 ± 18, and 31 ± 2.5 μl/45 min). Conclusion: Our results present the beneficial effects of NO combined with VSOP during the 1st hour of CS of WI-damaged experimental liver grafts.

Liver protection strategies in liver transplantation

BACKGROUND

Liver transplantation is the therapy of choice for patients with end-stage liver diseases. However, the gap between the low availability of organs and high demand is continuously increasing. Innovative strategies for organ protection are necessary to expand donor pool and to achieve better outcomes for liver transplantation. The present review analyzed and compared various strategies of liver protection.

DATA SOURCES

Databases such as PubMed, Embase and Ovid were searched for the literature related to donor liver protection strategies using following key words: "ischemia reperfusion injury", "graft preservation", "liver transplantation", "machine perfusion" and "conditioning". Of the 146 studies identified, only those with cutting edge strategies were analyzed.

RESULTS

A variety of therapeutic approaches were proposed to alleviate graft ischemia/reperfusion injury, which included static cold storage, machine perfusion (hypothermic, normothermic and subnormothermic), manual conditioning (pre, post and remote), and pharmacological conditioning. Evidences from animal experiments and clinical trials suggested that all these strategies could potentially protect liver graft; however, their clinical applications are limited partially due to their own disadvantages.

CONCLUSIONS

There are a plenty of methods suggested to decrease the degree of donor liver transplantation-related injury. However, none of these approaches is perfect in clinical practice. More translational researches (molecular and clinical studies) are needed to improve the techniques in liver graft protection.

Hypothermic machine preservation facilitates successful transplantation of "orphan" extended criteria donor livers

Hypothermic machine preservation (HMP) remains investigational in clinical liver transplantation. It is widely used to preserve kidneys for transplantation with improved results over static cold storage (SCS). At our center, we have used HMP in 31 adults receiving extended criteria donor (ECD) livers declined by the originating United Network for Organ Sharing region ("orphan livers"). These cases were compared to ECD SCS cases in a matched cohort study design. Livers were matched for donor age, recipient age, cold ischemic time, donor risk index and Model for End-Stage Liver Disease (MELD) score. HMP was performed for 3-7 h at 4-8 °C using our previously published protocol. Early allograft dysfunction rates were 19% in the HMP group versus 30% in the control group (p = 0.384). One-year patient survival was 84% in the HMP group versus 80% in the SCS group (p = NS). Post hoc analysis revealed significantly less biliary complications in the HMP group versus the SCS group (4 vs. 13, p = 0.016). Mean hospital stay was significantly shorter in the HMP group (13.64 ± 10.9 vs. 20.14 ± 11.12 days in the SCS group, p = 0.001). HMP provided safe and reliable preservation in orphan livers transplanted at our center.

Liver preservation with SCOT 15 solution decreases posttransplantation cholestasis compared with University of Wisconsin solution: a retrospective study

BACKGROUND

SCOT 15 is a new solution to preserve abdominal organs for transplantation. Its principal characteristic is the use of polyethylene glycol. Herein We report our experience using SCOT 15 compared with the reference University of Wisconsin (UW) solution for hepatic transplantation.

METHODS

We compared 2 groups: SCOT 15 (n = 33; 2009-2010) versus UW (n = 34; 2008-2010), which were paired for cold and warm ischemic times, donor ages, and graft weights. Endpoints were biologic tests in the first 2 months after the operation. A linear mixed model was used to evaluate longitudinal changes and influences of each solution.

RESULTS

No primary failure was observed. At postoperative day 0, transaminase values were higher in the SCOT 15 than in the UW group: aspartate transaminase: 2,435 ± 399 vs 589 ± 83 IU/L (P < .01); alanine transaminase: ALT: 1,207 ± 191 vs 484 ± 64 IU/L (P < .05), then returned to low levels in both groups. From day 0 to 8, coagulation factors reached normal values; there was no difference between the 2 groups. Total bilirubin decreased similarly in the 2 groups. However, from the second postoperative week (W1) to W8, the SCOT 15 group showed a slow decrease in the mean values of gamma-glutamyltranspeptidase (gGT) from 233 ± 125 to 130 ± 161 IU/L, which were significantly lower than those in the UW group, where the gGT remained around 300 IU/L (P < .01). The End-Stage Liver Disease, Child-Pugh, or United Network for Organ Sharing scores, primary liver diseases, hepatitic C virus status, arterial or biliary complications, and male/female ratio, which was different in the 2 groups, did not statistically influence these results.

CONCLUSIONS

The main effect of cold storage of human liver using SCOT 15 compared with UW solution was to decrease cholestasis following transplantation.

Comparable outcome of liver transplantation with histidine-tryptophan-ketoglutarate vs. University of Wisconsin preservation solution: a retrospective observational double-center trial

Background

The question of whether the choice of preservation solution affects outcome after liver transplantation is still not satisfactorily answered. The purpose of this study is to examine the preservation solutions’ impact on outcome after liver transplantation.

Methods

A double-center retrospective study of short- and long-term results of 3134 consecutive liver transplantations with follow-up periods up to 23 years was performed applying multivariate, risk-adjusted analyses with a subset for living-donor transplants, pediatric transplants and cases with prolonged cold ischemic times. An additional focus was put on biliary complications. The primary study endpoints were short- and long-term patient survival and death-censored graft survival. Secondary study endpoints were the occurrence of post-transplant complications, the necessity of operative revisions, the length of hospital stay, and the length of intensive care unit stay.

Results

Although long-term graft survival appears to be increased by Histidine-Tryptophan-Ketoglutarate-use (p = 0.018), this effect could not be confirmed in risk-adjusted analysis (p = 0.641). Multivariate regression analysis revealed that 3-month mortality (p = 0.120), 3-month graft survival (p = 0.103) and long-term patient survival (p = 0.235) were not influenced by the choice of preservation solution. There was no difference in the occurrence of common complications or necessity of operative revisions after liver transplantation. This was confirmed in subgroup analyses for living donor and pediatric transplantation and cases with prolonged cold ischemic time. Analysis of the preservation solutions’ impact on length of hospital (p = 0.113) and intensive care unit stay (p = 0.481) revealed no significant difference.

Conclusions

University of Wisconsin and Histidine-Tryptophan-Ketoglutarate solutions are clinically equivalent. Histidine-Tryptophan-Ketoglutarate solution could have an economically superior profile. The notion that the choice of preservation solution can have an impact on the onset of biliary complications after liver transplantation remains a matter of controversy.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-230X-14-169) contains supplementary material, which is available to authorized users.

Assessing warm ischemic injury of pig livers at hypothermic machine perfusion

BACKGROUND

Livers originating from donation after circulatory death (DCD) donors are exposed to warm ischemia (WI) before liver transplantation (LTx). Currently, there are no objective tests to evaluate the damage sustained before LTx. This study aims to identify surrogate markers for liver injury that can be assessed during hypothermic machine perfusion (HMP) preservation. In addition, we want to use mathematical equation modeling combining these markers to improve our assessment of DCD livers for transplantation.

MATERIALS AND METHODS

Porcine livers were exposed to incremental periods of WI (0-120 min) and subsequently HMP preserved for 4 h. Biochemical and hemodynamic parameters were repeatedly measured in the perfusate during HMP. Subsequently, to mimic LTx, normothermic isolated-liver perfusion was applied for 2 h and the injury assessed using a morphological score.

RESULTS

With increasing WI periods, the perfusate became more acidotic, and levels of aspartate aminotransferase (AST), liver fatty acid binding protein, redox-active iron, and arterial vascular resistance increased. A damage index, combining AST and pH (damage index = 2 - 37 × β(AST) - 257 × β(pH)) based on multifactorial analysis of the changing pattern of these markers, had increased sensitivity and specificity to reflect WI and reperfusion injury.

CONCLUSIONS

This proof of concept study demonstrated the potential role for objective evaluation of DCD porcine livers during HMP and the advantage to use multifactorial analysis on the markers' changing pattern.

Efficacy of liver graft washout as a function of the perfusate, pressure, and temperature

Donor graft washout can be impaired by colloids in organ preservation solutions that increase the viscosity and agglutinative propensity of red blood cells (RBCs) and potentially decrease organ function. The colloid-induced agglutinative effects on RBCs and RBC retention after liver washout with Ringer's lactate (RL), histidine tryptophan ketoglutarate solution, University of Wisconsin solution, and Polysol were determined as a function of the washout pressure (15 or 100 mm Hg) and temperature (4 or 37°C) in a rat liver washout model with (99m) Tc-pertechnetate-labeled RBCs. Colloids (polyethylene glycol in Polysol and hydroxyethyl starch in University of Wisconsin) induced RBC agglutination, regardless of the solution's composition. RL was associated with the lowest degree of (99m) Tc-pertechnetate-labeled RBC retention after simultaneous arterial and portal washout at 37°C and 100 mm Hg. RL washout was also associated with the shortest washout time. A single portal washout with any of the solutions did not result in differences in the degree of RBC retention, regardless of the temperature or pressure. In conclusion, no differences were found in portal washout efficacy between colloidal solutions, histidine tryptophan ketoglutarate, and RL. Simultaneous arterial and portal washout with RL at 37°C and 100 mm Hg resulted in the least RBC retention and the shortest washout time.

Supercooling as a viable non-freezing cell preservation method of rat hepatocytes

Supercooling preservation holds the potential to drastically extend the preservation time of organs, tissues and engineered tissue products, and fragile cell types that do not lend themselves well to cryopreservation or vitrification. Here, we investigate the effects of supercooling preservation (SCP at -4(o)C) on primary rat hepatocytes stored in cryovials and compare its success (high viability and good functional characteristics) to that of static cold storage (CS at +4(o)C) and cryopreservation. We consider two prominent preservation solutions a) Hypothermosol (HTS-FRS) and b) University of Wisconsin solution (UW) and a range of preservation temperatures (-4 to -10 (o)C). We find that there exists an optimum temperature (-4(o)C) for SCP of rat hepatocytes which yields the highest viability; at this temperature HTS-FRS significantly outperforms UW solution in terms of viability and functional characteristics (secretions and enzymatic activity in suspension and plate culture). With the HTS-FRS solution we show that the cells can be stored for up to a week with high viability (~56%); moreover we also show that the preservation can be performed in large batches (50 million cells) with equal or better viability and no loss of functionality as compared to smaller batches (1.5 million cells) performed in cryovials.

Liver defatting: an alternative approach to enable steatotic liver transplantation

Macrovesicular steatosis in greater than 30% of hepatocytes is a significant risk factor for primary graft nonfunction due to increased sensitivity to ischemia reperfusion (I/R) injury. The growing prevalence of hepatic steatosis due to the obesity epidemic, in conjunction with an aging population, may negatively impact the availability of suitable deceased liver donors. Some have suggested that metabolic interventions could decrease the fat content of liver grafts prior to transplantation. This concept has been successfully tested through nutritional supplementation in a few living donors. Utilization of deceased donor livers, however, requires defatting of explanted organs. Animal studies suggest that this can be accomplished by ex vivo warm perfusion in a time scale of a few hours. We estimate that this approach could significantly boost the size of the donor pool by increasing the utilization of steatotic livers. Here we review current knowledge on the mechanisms whereby excessive lipid storage and macrosteatosis exacerbate hepatic I/R injury, and possible approaches to address this problem, including ex vivo perfusion methods as well as metabolically induced defatting. We also discuss the challenges ahead that need to be addressed for clinical implementation.

Assist devices: machine preservation of extended criteria donors

1. Hypothermic machine perfusion (HMP) is in its infancy in clinical liver transplantation. Potential benefits include diminished preservation injury (PI) and improved graft function. 2. We have employed HMP in 21 extended criteria donor (ECD livers) at our center with excellent clinical outcomes. 3. Our experience with liver HMP is the only reported clinical experience worldwide representing a total of 41 successful liver transplant cases showing improved outcomes and diminished markers of ischemia/reperfusion injury. 4. Further multicenter and large scale trials are now warranted to further explore the benefits and applicability of liver HMP into the clinical mainstream.

Innovations in organ donation

The growing disparity between organ availability for transplantation and the number of patients in need has challenged the donation and transplantation community of practice to develop innovative processes, ideas, and techniques to bridge the gaps. Advances in the sharing of best practices in the donation community have contributed greatly over the last 8 years. Broader sharing of updated guidelines for declaration of brain death in conjunction with improvements in deceased donor management have increased opportunities for organ donation. New techniques for organ preservation and organ resuscitation have allowed for better utilization of the potential donor pool. This review will highlight processes, ideas, and techniques in organ donation.

The role of normothermic extracorporeal perfusion in minimizing ischemia reperfusion injury

The primary objective of organ preservation is to deliver a viable graft with minimal risk of impaired postoperative graft function. In current clinical practice, preservation of transplanted organs is based on hypothermia. Organs are flushed and stored using specific preservation solutions to reduce cellular metabolism and prevent cell swelling. However, the ongoing organ donor shortage and consequent expansion of donor criteria to include the use of grafts that would once have been discarded as unsuitable have underlined the need for a technique that prevents any further damage during the preservation period. The principle of normothermic machine perfusion preservation is the maintenance of cellular metabolism in a physiological environment throughout the preservation period. Normothermic preservation, at least in theory, thereby overcomes the 3 major weaknesses inherent in traditional static cold storage by (1) avoiding ischemia/reperfusion injury, (2) avoiding cold injury, and (3) allowing viability assessment. Furthermore, normothermic machine perfusion might transpire to be the ideal vehicle to deliver other therapeutic interventions during preservation to modulate and optimize the graft before transplantation. By restoring function in marginal donor organs and enabling the clinician to appraise its viability, the donor pool might be greatly expanded.

An innovative hyperbaric hypothermic machine perfusion protects the liver from experimental preservation injury

Purpose. Hypothermic machine perfusion systems seem more effective than the current static storage to prevent cold ischemic liver injury. Thus, we test an innovative hyperbaric hypothermic machine perfusion (HHMP), which combines hyperbaric oxygenation of the preservation solution and continuous perfusion of the graft. Methods. Rat livers were preserved with Celsior solution according to 4 different modalities: normobaric static preservation; hyperbaric static preservation at 2 atmosphere absolute (ATA); normobaric dynamic preservation, with continuous perfusion; hyperbaric dynamic preservation, with continuous perfusion at 2 ATA. After 24 h cold preservation, we assessed different parameters. Results. Compared to baseline, livers preserved with the current static storage showed severe ultrastructural damage, glycogen depletion and an increased oxidative stress. Normobaric perfused livers showed improved hepatocyte ultrastructure and ameliorated glycogen stores, but they still suffered a significant oxidative damage. The addition of hyperbaric oxygen produces an extra benefit by improving oxidative injury and by inducing endothelial NO synthase (eNOS) gene expression. Conclusions. Preservation by means of the present innovative HHMP reduced the liver injury occurring after the current static cold storage by lowering glycogen depletion and oxidative damage. Interestingly, only the use of hyperbaric oxygen was associated to a blunted oxidative stress and an increased eNOS gene expression.

Impact of venous systemic oxygen persufflation supplemented with nitric oxide gas on cold-stored, warm ischemia-damaged experimental liver grafts

The increasing shortage of donor organs has led to the increasing use of organs from non-heart-beating donors. We aimed to assess the impact of venous systemic oxygen persufflation (VSOP) supplemented with nitric oxide (NO) gas during the cold storage (CS) of warm ischemia (WI)-damaged experimental liver grafts. Rat livers (n = 5 per group) were retrieved after 30 minutes of WI induced by cardiac arrest (the WI group) and were thereafter preserved for 24 hours by CS in histidine tryptophan ketoglutarate solution. During CS, gaseous oxygen was insufflated via the caval vein with 40 ppm NO (the VSOP-NO group) or without NO (the VSOP group). Cold-stored livers without WI served as controls. Liver viability was assessed after the preservation period by normothermic isolated reperfusion for 45 minutes with oxygenated Krebs-Henseleit buffer. After 45 minutes of reperfusion, the VSOP-NO-treated livers showed significantly lower alanine aminotransferase values than the WI-damaged livers (10.2 ± 0.2 versus 78.2 ± 14.6 IU/L), whereas the control livers showed no differences from the VSOP-NO-treated livers. The mitochondrial enzyme release was lower in the VSOP-NO group (4.0 ± 0.7 IU/L) versus the WI group (18.2 ± 4.9 IU/L). An increased portal vein pressure was observed throughout reperfusion (45 minutes) in the WI group (21.7 ± 0.2 mm Hg) versus the VSOP-NO group (12.2 ± 0.8 mm Hg) and the control group (19.9 ± 0.4 mm Hg). Furthermore, the NO concentration in the perfusate after 5 minutes of reperfusion was highest in the VSOP-NO group. The release of malondialdehyde into the perfusate was significantly reduced in the VSOP-NO group (0.9 ± 0.1 nmol/mL) versus the WI group (31.3 ± 5.3 nmol/mL). In conclusion, the resuscitation of livers after 30 minutes of WI to a level comparable to that of nonischemically damaged livers is possible with VSOP supplemented with NO gas. Moreover, the application of VSOP with NO minimizes the extent of injuries caused by oxygen free radicals during preservation.

Soluble cytokeratin 18 biomarkers may provide information on the type of cell death during early ischemia and reperfusion periods of liver transplantation

Hepatocellular damage takes place as a result of ischemia and reperfusion during liver transplantation (LT). To discriminate the type of cell death and quantitate its severity may provide new insights into the mechanisms of hepatocellular damage. Therefore, we investigated the type of cell death by ELISA-based assays in patient sera. Apoptosis was specifically assessed by measuring a novel soluble biomarker, the caspase-cleaved cytokeratin 18, while total cell death (apoptosis and necrosis) by cytokeratin 18 released from dead (necrotic and apoptotic) cells. Twenty-seven live (LDLT) and 14 deceased (DDLT) donor liver transplantations were analyzed before the operation, at the anhepatic stage, first, sixth and 24th hour after the reperfusion. Both apoptosis and total cell death have successfully been demonstrated although they have not been confirmed by the liver biopsy that is impossible to perform in this setting. Apoptosis was not induced in LDLT. Total cell death (primarily necrosis) only transiently appeared the first hour after the reperfusion in LDLT, while it sharply increased the first hour after the reperfusion and maintained its level in DDLT. Soluble cytokeratin 18 biomarkers seem to be useful to discriminate and quantitate the type of cell death during early ischemia and reperfusion periods of LT.

Prolonged survival of allografts induced by mycobacterial Hsp70 is dependent on CD4+CD25+ regulatory T cells

Background

Heat shock proteins (Hsps) are stress induced proteins with immunomodulatory properties. The Hsp70 of Mycobacterium tuberculosis (TBHsp70) has been shown to have an anti-inflammatory role on rodent autoimmune arthritis models, and the protective effects were demonstrated to be dependent on interleukin-10 (IL-10). We have previously observed that TBHsp70 inhibited maturation of dendritic cells (DCs) and induced IL-10 production by these cells, as well as in synovial fluid cells.

Methodology/Principal Findings

We investigated if TBHsp70 could inhibit allograft rejection in two murine allograft systems, a transplanted allogeneic melanoma and a regular skin allograft. In both systems, treatment with TBHsp70 significantly inhibited rejection of the graft, and correlated with regulatory T cells (Tregs) recruitment. This effect was not tumor mediated because injection of TBHsp70 in tumor-free mice induced an increase of Tregs in the draining lymph nodes as well as inhibition of proliferation of lymph node T cells and an increase in IL-10 production. Finally, TBHsp70 inhibited skin allograft acute rejection, and depletion of Tregs using a monoclonal antibody completely abolished this effect.

Conclusions/Significance

We present the first evidence for an immunosuppressive role for this protein in a graft rejection system, using an innovative approach – immersion of the graft tissue in TBHsp70 solution instead of protein injection. Also, this is the first study that demonstrates dependence on Treg cells for the immunosuppressive role of TBHsp70. This finding is relevant for the elucidation of the immunomodulatory mechanism of TBHsp70. We propose that this protein can be used not only for chronic inflammatory diseases, but is also useful for organ transplantation management.

Current state of hypothermic machine perfusion preservation of organs: The clinical perspective

This review focuses on the application of hypothermic perfusion technology as a topic of current interest with the potential to have a salutary impact on the mounting clinical challenges to improve the quantity and quality of donor organs and the outcome of transplantation. The ex vivo perfusion of donor organs on a machine prior to transplant, as opposed to static cold storage on ice, is not a new idea but is being re-visited because of the prospects of making available more and better organs for transplantation. The rationale for pursuing perfusion technology will be discussed in relation to emerging data on clinical outcomes and economic benefits for kidney transplantation. Reference will also be made to on-going research using other organs with special emphasis on the pancreas for both segmental pancreas and isolated islet transplantation. Anticipated and emerging benefits of hypothermic machine perfusion of organs are: (i) maintaining the patency of the vascular bed, (ii) providing nutrients and low demand oxygen to support reduced energy demands, (iii) removal of metabolic by-products and toxins, (iv) provision of access for administration of cytoprotective agents and/or immunomodulatory drugs, (v) increase of available assays for organ viability assessment and tissue matching, (vi) facilitation of a change from emergency to elective scheduled surgery with reduced costs and improved outcomes, (vii) improved clinical outcomes as demonstrated by reduced PNF and DGF parameters, (viii) improved stabilization or rescue of ECD kidneys or organs from NHBD that increase the size of the donor pool, (ix) significant economic benefit for the transplant centers and reduced health care costs, and (x) provision of a technology for ex vivo use of non-transplanted human organs for pharmaceutical development research.

Ex-vivo normothermic liver perfusion: an update

PURPOSE OF REVIEW

There is increasing disparity between the supply of acceptable donor organs and the number of potential transplant recipients. The shortage of organs for transplantation demands optimal utilization of a wider spectrum of donor organs, including nonheart-beating and other extended criteria donors. In the case of the liver, a substantial number of organs are discarded because of a risk of primary nonfunction.

RECENT FINDINGS

For many years hypothermic preservation has been the universal standard for organ preservation. Although limited in terms of the duration of preservation it has had the major advantages of simplicity, portability and affordability. Organ preservation by normothermic machine perfusion has repeatedly proven superiority over static cold storage in experimental settings. However, it is complex and costly and its place in clinical transplantation has not yet been established. In liver preservation normothermic perfusion provides the potential: (a) to preserve extended criteria grafts for long periods; (b) to assess the viability of these grafts during perfusion; and (c) to improve the condition of the grafts.

SUMMARY

Avoidance of cold ischaemic preservation damage and repair of injury sustained during warm ischaemia and organ procurement would potentially allow many livers from extended criteria donors to be transplanted reliably. The current challenges are, first to confirm the feasibility of the normothermic machine perfusion methodology in human livers and, second, to develop and introduce a functional device into the clinical arena.

New insights into fatty liver preservation using Institute Georges Lopez preservation solution

Institute Georges Lopez preservation solution (IGL-1) has been demonstrated to be useful for fatty liver preservation. The mechanisms responsible for this effective graft protection against ischemia-reperfusion injury are pivotal actions on generation of nitric oxide a diffusible molecule with vasodilator properties, that facilitates the up-regulation of other well-known cytoprotective genes, such as hypoxia-inducible factor-1 alpha (HIF-1alpha) and heme-oxygenase 1 (HO-1). During normoxic reperfusion, the presence of nitric oxide permits HIF-1alpha accumulation to inhibit prolyl-hydoxylases, thus promoting an additional overexpression of the HO-1 in steatotic and nonsteatotic graft livers preserved in IGL-1.

Pharmacological strategies against cold ischemia reperfusion injury

IMPORTANCE OF THE FIELD

Good organ preservation is a determinant of graft outcome after revascularization. The necessity of increasing the quality of organ preservation, as well as of extending cold storage time, has made it necessary to consider the use of pharmacological additives.

AREAS COVERED IN THIS REVIEW

The complex physiopathology of cold-ischemia-reperfusion (I/R) injury--and in particular cell death, mitochondrial injury and endoplasmic reticulum stress--are reviewed. Basic principles of the formulation of the different preservation solutions are discussed.

WHAT THE READER WILL GAIN

Current strategies and new trends in static organ preservation using additives such as trimetazidine, polyethylene glycols, melatonin, trophic factors and endothelin antagonists in solution are presented and discussed. The benefits and mechanisms responsible for enhancing organ protection against I/R injury are also discussed. Graft preservation was substantially improved when additives were added to the preservation solutions.

TAKE HOME MESSAGE

Enrichment of preservation solutions by additives is clinically useful only for short periods. For longer periods of cold ischemia, the use of such additives becomes insufficient because graft function deteriorates as a result of ischemia. In such conditions, the preservation strategy should be changed by the use of machine perfusion in normothermic conditions.

Hypothermic machine preservation attenuates ischemia/reperfusion markers after liver transplantation: preliminary results

BACKGROUND

Hypothermic machine perfusion (HMP) has shown significant benefits in renal transplantation but is still in its infancy in liver transplantation. Potential benefits include diminished preservation injury and improved early graft function.

METHODS

We analyzed liver tissue and effluent collected during our Phase 1 trial of liver HMP. Liver allografts underwent HMP for 4-7 h using dual centrifugal perfusion with Vasosol solution at 4-8°C were transplanted and compared with cold stored (CS) transplant controls. Histology, reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemistry on liver biopsies compared histology and expression of early proinflammatory cytokines, IL-8 and TNF-α, and intracellular adhesion molecule-1 (ICAM-1). Gel electrophoresis was used to evaluate effluent protein content representing residual metabolism.

RESULTS

We saw no differences between HMP and CS in early histologic findings after reperfusion. RT-PCR of reperfusion biopsy samples in the CS group showed high expression of proinflammatory cytokines and ICAM-1. This up-regulation was significantly attenuated by HMP (ICAM-1; P = 0.0152) (IL-8; P = 0.0014) (TNF-α; P = 0.0284). This was confirmed with immunohistochemistry. Albumin was identified in the perfusate throughout HMP.

CONCLUSIONS

HMP significantly reduced proinflammatory cytokine expression compared with CS controls. Further studies of human liver HMP with detailed molecular investigations are now warranted to elucidate benefits of HMP in liver transplantation.

Hypothermic machine preservation in human liver transplantation: the first clinical series

Hypothermic machine perfusion (HMP) is widely used to preserve kidneys for transplantation with improved results over cold storage (CS). To date, successful transplantation of livers preserved with HMP has been reported only in animal models. In this, the first prospective liver HMP study, 20 adults received HMP-preserved livers and were compared to a matched group transplanted with CS livers. HMP was performed for 3-7 h using centrifugal perfusion with Vasosol solution at 4-6 degrees C. There were no cases of primary nonfunction in either group. Early allograft dysfunction rates were 5% in the HMP group versus 25% in controls (p = 0.08). At 12 months, there were two deaths in each group, all unrelated to preservation or graft function. There were no vascular complications in HMP livers. Two biliary complications were observed in HMP livers compared with four in the CS group. Serum injury markers were significantly lower in the HMP group. Mean hospital stay was shorter in the HMP group (10.9 +/- 4.7 days vs. 15.3 +/- 4.9 days in the CS group, p = 0.006). HMP of donor livers provided safe and reliable preservation in this pilot case-controlled series. Further multicenter HMP trials are now warranted.

Hypothermic organ preservation by static storage methods: Current status and a view to the future

The donor organ shortage is the largest problem in transplantation today and is one where organ preservation technology has an important role to play. Static storage of solid organs, especially of the kidney, continues to be the most common method employed for storage and transport of organs from deceased donors. However, the increase in organs obtained from expanded criteria donors and donors with cardiac death provide new challenges in crafting effective preservation methods for the future. This article reviews the current status of static hypothermic storage methods and discusses potential avenues for future exploitation of this technology as the available organ pool is expanded into the more marginal donor categories.

Liver transplantation using donation after cardiac death donors: long-term follow-up from a single center

There is a lack of universally accepted clinical parameters to guide the utilization of donation after cardiac death (DCD) donor livers and it is unclear as to which patients would benefit most from these organs. We reviewed our experience in 141 patients who underwent liver transplantation using DCD allografts from 1993 to 2007. Patient outcomes were analyzed in comparison to a matched cohort of 282 patients who received livers from donation after brain death (DBD) donors. Patient survival was similar, but 1-, 5- and 10-year graft survival was significantly lower in DCD (69%, 56%, 44%) versus DBD (82%, 73%, 63%) subjects (p < 0.0001). Primary nonfunction and biliary complications were more common in DCD patients, accounting for 67% of early graft failures. A donor warm ischemia time >20 min, cold ischemia time >8 h and donor age >60 were associated with poorer DCD outcomes. There was a lack of survival benefit in DCD livers utilized in patients with model for end-stage liver disease (MELD) < or =30 or those not on organ-perfusion support, as graft survival was significantly lower compared to DBD patients. However, DCD and DBD subjects transplanted with MELD >30 or on organ-perfusion support had similar graft survival, suggesting a potentially greater benefit of DCD livers in critically ill patients.