Principles of solid-organ preservation by cold storage

Adding the oxygen carrier M101 to a cold-storage solution could be an alternative to HOPE for liver graft preservation

Background & Aims

Hypothermic oxygenated machine perfusion (HOPE) is a promising technique for providing oxygen to the liver during graft preservation; however, because of associated logistical constraints, addition of an oxygen transporter to static cold-storage solutions (SCS) might be easier. M101 is marine worm haemoglobin that has been shown to improve kidney preservation in the clinic when added to SCS. This study evaluated the effects of the addition of M101 to SCS on the quality of pig liver graft preservation.

Methods

Pig liver grafts were preserved using SCS, HOPE, or SCS+M101, and the liver functions were compared during cold preservation and after orthotopic allotransplantation (OLT) in pigs.

Results

During preservation of the liver grafts, mitochondrial function, ATP synthesis, antioxidant capacities, and hepatocyte architecture were better preserved, and free radical production, antioxidant activities, and inflammatory mediators were lower, with HOPE or SCS+M101 than with SCS alone. However, after 1 h of preservation, liver functions with HOPE were superior to those with SCS+M101. After 6 h of preservation and OLT, blood levels of aspartate and alanine aminotransferases and lactate dehydrogenase increased with a peak effect at Day 1 post-transplant; values were similar with HOPE and SCS+M101, and were significantly lower than those in the SCS group. At Days 1 and 3, tumor necrosis factor α levels remained lower with HOPE and SCS+M101 vs. SCS. At Day 7, liver cell necrosis and inflammation were less marked in both oxygenated groups.

Conclusions

When added to SCS, M101 effectively oxygenates liver grafts during preservation, preventing post-transplant injury; although graft performances are below those achieved with HOPE.

Lay summary

When transported between donors and recipients, even cold-stored liver grafts need oxygen to maintain their viability. To provide them with oxygen, we added a marine worm super haemoglobin (M101) to the cold-storage solution UWCS. Using a pig liver transplant model, we revealed that livers cold stored with UWCS+M101 showed improved oxygenation compared with simple cold-storage solutions, but did not reach the oxygenation level achieved with machine perfusion.

Prospective, single-centre, randomised controlled trial to evaluate the efficacy and safety of ischaemia-free liver transplantation (IFLT) in the treatment of end-stage liver disease

INTRODUCTION

During conventional liver transplantation (CLT), ischaemia-reperfusion injury (IRI) is inevitable and is associated with complications such as early allograft dysfunction (EAD), primary non-function and ischaemic-type biliary lesions. We have established a novel procedure called ischaemia-free liver transplantation (IFLT). The results from a pilot study suggest that IFLT might prevent IRI and yield better transplant outcomes than CLT. The purpose of this study was to further assess the efficacy and safety of IFLT versus CLT in patients with end-stage liver disease.

METHODS AND ANALYSIS

This is an investigator-initiated, open-label, phase III, prospective, single-centre randomised controlled trial on the effects of IFLT in patients with end-stage liver disease. Adult patients (aged 18-75 years) eligible for liver transplantation will be screened for participation in this trial and will be randomised between the IFLT group (n=34) and the CLT group (n=34). In the IFLT group, the donor liver will be procured, preserved and implanted with continuous normothermic machine perfusion (NMP). In the CLT group, the donor liver will be procured after a fast cold flush, preserved in 0°C-4°C solution and implanted under hypothermic and hypoxic conditions. Patients in both groups will be managed according to the standard protocol of our centre. The primary end point is the incidence of EAD after liver transplantation. Intraoperative and postoperative parameters of donor livers and recipients will be observed and recorded, and postoperative liver graft function, complications and recipient and graft survival will be evaluated. After a 12-month follow-up of the last enrolled recipient, the outcomes will be analysed to evaluate the safety and efficacy of IFLT versus CLT in patients with end-stage liver disease.

ETHICS AND DISSEMINATION

The protocol was reviewed and approved by the Ethics Committee of The First Affiliated Hospital of Sun Yat-sen University. The findings will be disseminated to the public through conference presentations and peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

ChiCTR1900021158.

Current techniques and the future of lung preservation

Although lung transplant remains the only option for patients suffering from end-stage lung failure, donor supply is insufficient to meet demand. Static cold preservation is the most common method to preserve lungs in transport to the recipient; however, this method does not improve lung quality and only allows for 8 h of storage. This results in lungs which become available for donation but cannot be used due to failure to meet physiologic criteria or an inability to store them for a sufficient time to find a suitable recipient. Therefore, lungs lost due to failure to meet physiological or compatibility criteria may be mitigated through preservation methods which improve lung function and storage durations. Ex situ lung perfusion (ESLP) is a recently developed method which allows for longer storage times and has been demonstrated to improve lung function such that rejected lungs can be accepted for donation. Although greater use of ESLP will help to improve donor lung utilization, the ability to cryopreserve lungs would allow for organ banking to better utilize donor lungs. However, lung cryopreservation research remains underrepresented in the literature despite its unique advantages for cryopreservation over other organs. Therefore, this review will discuss the current techniques for lung preservation, static cold preservation and ESLP, and provide a review of the cryopreservation challenges and advantages unique to lungs.

IGL-1 preservation solution in kidney and pancreas transplantation: A systematic review

We aimed to systematically review published data on the effectiveness of Institut Georges Lopez-1 (IGL-1) as a preservation solution for kidney and pancreas grafts. A systematic literature search of PubMed, Embase, Web of Science, and the Cochrane Library databases was performed. Human studies evaluating the effects of IGL-1 preservation solution in kidney and/or pancreas transplantation were included. Outcome data on kidney and pancreas graft function were extracted. Of 1513 unique articles identified via the search strategy, four articles could be included in the systematic review. Of these, two retrospective studies reported on the outcome of IGL-1 compared to University of Wisconsin (UW) solution in kidney transplantation. These show kidneys preserved in IGL-1 had improved early function (2 weeks post-transplant) compared to UW. Follow-up was limited to 1 year and showed similar graft and patient survival rates when reported. Two case series described acceptable early outcomes (up to 1 month) of simultaneous kidney pancreas transplantation after storage in IGL-1. As only four clinical papers were identified, we widened our search to include four eligible large animal studies. Three compared IGL-1 with UW in pig kidney transplant models with inconclusive or mildly positive results. One pig pancreas transplant study suggested better early outcome with IGL-1 compared to UW. Too few published data are available to allow any firm conclusions to be drawn on the effectiveness of IGL-1 as a preservation solution of kidney and pancreas grafts. The limited available data show satisfactory early outcomes though no medium to long-term outcomes have been described. Further well-designed clinical studies are needed.

Protective potential effects of fucoidan in hepatic cold ischemia-rerfusion injury in rats

The necessity to increase the efficiency of organ preservation has pushed physicians to consider the use of pharmacological additives in preservation solutions to minimize ischemia reperfusion injury. Here, we evaluated the effect of fucoidan, sulfated polysaccharide from brown seaweed, as an additive to IGL-1 (Institut Georges Lopez) preservation solution. Livers from Wistar rats were preserved for 24 h at 4 °C in IGL-1 solution, enriched or not with fucoidan (100 mg/L). Thereafter, they were subjected to reperfusion (2 h, at 37 °C) using an isolated perfused rat liver model. The addition of fucoidan to IGL-1 solution reduced hepatic injury (AST, ALT) and improved liver function compared to IGL-1 solution without fucoidan. In addition, we noted a significant increase in the phosphorylation of AMPK, AKT protein kinase and GSK3-β, leading to a reduction in VDAC phosphorylation, as well as a reduction in apoptosis (caspase 3), mitochondrial damage, oxidative stress and endoplasmic reticulum (ER) stress markers. Furthermore, ERK1/2 and P38 MAPKs phosphorylation significantly decreased after supplementation of IGL-1 solution with fucoidan. In conclusion, the supplementation of IGL-1 solution with fucoidan maintained liver graft integrity and function through the prevention of the ER stress, oxidative stress and mitochondrial dysfunction. Fucoidan could be considered as potential natural therapeutic agent to alleviate graft injury.

Ischemia-Reperfusion Injury in Marginal Liver Grafts and the Role of Hypothermic Machine Perfusion: Molecular Mechanisms and Clinical Implications

Ischemia-reperfusion injury (IRI) constitutes a significant source of morbidity and mortality after orthotopic liver transplantation (OLT). The allograft is metabolically impaired during warm and cold ischemia and is further damaged by a paradox reperfusion injury after revascularization and reoxygenation. Short-term and long-term complications including post-reperfusion syndrome, delayed graft function, and immune activation have been associated with IRI. Due to the current critical organ shortage, extended criteria grafts are increasingly considered for transplantation, however, with an elevated risk to develop significant features of IRI. In recent years, ex vivo machine perfusion (MP) of the donor liver has witnessed significant advancements. Here, we describe the concept of hypothermic (oxygenated) machine perfusion (HMP/HOPE) approaches and highlight which allografts may benefit from this technology. This review also summarizes clinical applications and the main aspects of ongoing randomized controlled trials on hypothermic perfusion. The mechanistic aspects of IRI and hypothermic MP-which include tissue energy replenishment, optimization of mitochondrial function, and the reduction of oxidative and inflammatory damage following reperfusion-will be comprehensively discussed within the context of current preclinical and clinical evidence. Finally, we highlight novel trends and future perspectives in the field of hypothermic MP in the context of recent findings of basic and translational research.

Hypothermic Oxygenated Perfusion Versus Static Cold Storage for Expanded Criteria Donors in Liver and Kidney Transplantation: Protocol for a Single-Center Randomized Controlled Trial

Background

Extended criteria donors (ECD) are widely utilized due to organ shortage, but they may increase the risk of graft dysfunction and poorer outcomes. Hypothermic oxygenated perfusion (HOPE) is a recent organ preservation strategy for marginal kidney and liver grafts, allowing a redirect from anaerobic metabolism to aerobic metabolism under hypothermic conditions and protecting grafts from oxidative species–related damage. These mechanisms may improve graft function and survival.

Objective

With this study, we will evaluate the benefit of end-ischemic HOPE on ECD grafts for livers and kidneys as compared to static cold storage (SCS). The aim of the study is to demonstrate the ability of HOPE to improve graft function and postoperative outcomes of ECD kidney and liver recipients.

Methods

This is an open-label, single-center randomized clinical trial with the aim of comparing HOPE with SCS in ECD kidney and liver transplantation. In the study protocol, which has been approved by the ethics committee, 220 patients (110 liver recipients and 110 kidney recipients) will be enrolled. Livers and kidneys assigned to the HOPE group undergo machine perfusion with cold Belzer solution (4-10°C) and continuous oxygenation (partial pressure of oxygen of 500-600 mm Hg). In the control group, livers and kidneys undergoing SCS are steeped in Celsior solution and stored on ice. Using the same perfusion machine for both liver and kidney grafts, organs are perfused from the start of the back-table procedure until implantation, without increasing the cold ischemia time. For each group, we will evaluate clinical outcomes, graft function tests, histologic findings, perfusate, and the number of allocated organs. Publication of the results is expected to begin in 2021.

Results

Dynamic preservation methods for organs from high-risk donors should improve graft dysfunction after transplantation. To date, we have recruited 108 participants. The study is ongoing, and recruitment of participants will continue until January 2020.

Conclusions

The proposed preservation method should improve ECD graft function and consequently the postoperative patient outcomes.

Trial Registration

ClinicalTrials.gov NCT03837197; https://clinicaltrials.gov/ct2/show/NCT03837197 ; Archived by WebCite® at http://www.webcitation.org/76fSutT3R

International Registered Report Identifier (IRRID)

DERR1-10.2196/13922

Evaluation of Intrahepatic Lactate/Pyruvate Ratio As a Marker for Ischemic Complications Early After Liver Transplantation-A Clinical Study

Background.

Lactate/pyruvate ratio has been introduced as a sensitive marker for ischemia in the transplanted liver. In the present study, we aimed to evaluate lactate/pyruvate ratio measured in the liver by microdialysis as a marker for ischemic complications early after liver transplantation.

Methods.

Forty-five patients undergoing liver transplantation were included in the study. A microdialysis catheter was placed in the liver graft directly following liver transplantation and the metabolites lactate and pyruvate measured for up to 6 days and the lactate/pyruvate ratio calculated. The association between increased intrahepatic lactate/pyruvate ratio and ischemic complications was studied.

Results.

One of 45 patients developed hepatic arterial thrombosis. Forty-four events with increased lactate/pyruvate ratio were identified in 24 patients. In none of the 24 patients that had a raised lactate/pyruvate ratio could we detect occurrence of any ischemic complication. In the patient that did have hepatic arterial thrombosis, the lactate/pyruvate ratio did not show a significant prolonged rise.

Conclusions.

An increase in the intrahepatic lactate/pyruvate ratio is not necessarily indicative of ischemic complications and is thus not a reliable marker for monitoring of clinically significant ischemia in the liver early after transplantation.

Combination of Euro-Collins and University of Wisconsin Solution: An Effective and Economic Substitute for Organ Procurement

PURPOSE

Many types of preservation fluid were used in liver procurement. Undoubtedly, the gold standard is the University of Wisconsin (UW) solution. But the solution is expensive. The aim of this study was to evaluate the results of combined acetated Ringer solution, Euro-Collins solution, and UW solution.

MATERIALS AND METHODS

All patients undergoing adult liver transplantation from cadaveric donor during January 2013 to December 2017 in King Chulalongkorn Memorial Hospital were included in this study. Donor and recipient characteristics, preservation fluid, operative data, and postoperative outcomes were recorded.

RESULTS

A total of 102 patients receiving liver transplants were enrolled into the study. The mean age of donors was 34.2 years. The mean total ischemic time was 420.93 minutes. In recipients, posttransplantation complications were the following: (1) primary nonfunction in 1 patient (0.98%); (2) early allograft dysfunction in 23 patients (22.5%); (3) hepatic artery thrombosis in 3 patients (2.7%); (4) hepatic venous outflow obstruction in 2 patients (1.96%); (5) biliary leakage in 1 patient (0.98%); (6) biliary anastomosis stenosis in 4 patients (3.92%); and (7) biliary nonanastomosis stenosis in 1 patient (0.98%). No inhospital mortality was occurred. Overall mortality rate is 7.8% (8/102). One-, 3-, and 5-year survival were 95.9%, 91.5%, and 88.4%, respectively.

CONCLUSIONS

The combination of acetated Ringer solution, Euro-Collins solution, and UW solution is effective and economic for liver preservation. Further study should be conducted.

A prospective, randomized, single-blind, multicentre, phase III study on organ preservation with Custodiol-N solution compared with Custodiol® solution in organ transplantation (kidney, liver and pancreas)

BACKGROUND

Organ preservation before transplantation is still a challenge. Both the University of Wisconsin and Bretschneider's histidine-tryptophan-ketoglutarate (HTK; Custodiol®) solution are standard for liver, kidney and pancreas preservation. Organ preservation with both solutions is comparable; recently, however, Custodiol® solution has been modified to Custodiol-N according to the needs of today. Thus, our study was defined to study its effect in clinical transplantation.

METHODS

Patients undergoing kidney transplantation (n = 412) (including approximately 30 combined kidney-pancreas) or liver transplantation (n = 202) receive grafts that have been cold stored in either Custodiol® or Custodiol-N to demonstrate noninferiority of Custodiol-N regarding both graft function and graft injury after transplantation.

DISCUSSION

Preclinical data have clearly shown that Custodiol-N is superior to Custodiol® in cold static organ preservation via mechanisms including inhibition of hypoxic cell injury, cold-induced cell injury and avoidance of adverse effects during warm exposure to the solution. Further clinical safety data on Custodiol-N for cardioplegia are available. Thus, this study was designed to compare Custodiol® with Custodiol-N for the first time in a prospective, randomized, single-blinded, multicentre, phase III clinical transplantation trial.

TRIAL REGISTRATION

Eudra-CT, 2017-002198-20. Registered on 28 November 2018.

scRNA-seq assessment of the human lung, spleen, and esophagus tissue stability after cold preservation

BACKGROUND

The Human Cell Atlas is a large international collaborative effort to map all cell types of the human body. Single-cell RNA sequencing can generate high-quality data for the delivery of such an atlas. However, delays between fresh sample collection and processing may lead to poor data and difficulties in experimental design.

RESULTS

This study assesses the effect of cold storage on fresh healthy spleen, esophagus, and lung from ≥ 5 donors over 72 h. We collect 240,000 high-quality single-cell transcriptomes with detailed cell type annotations and whole genome sequences of donors, enabling future eQTL studies. Our data provide a valuable resource for the study of these 3 organs and will allow cross-organ comparison of cell types. We see little effect of cold ischemic time on cell yield, total number of reads per cell, and other quality control metrics in any of the tissues within the first 24 h. However, we observe a decrease in the proportions of lung T cells at 72 h, higher percentage of mitochondrial reads, and increased contamination by background ambient RNA reads in the 72-h samples in the spleen, which is cell type specific.

CONCLUSIONS

In conclusion, we present robust protocols for tissue preservation for up to 24 h prior to scRNA-seq analysis. This greatly facilitates the logistics of sample collection for Human Cell Atlas or clinical studies since it increases the time frames for sample processing.

Post-Reperfusion Syndrome in Liver Transplantation: Does a Caval Blood Flush Vent Help?

BACKGROUND Post-reperfusion syndrome (PRS) during liver transplantation can range from a benign event to a profound hemodynamic excursion from baseline with significant morbidity. Multiple variables can be responsible for the diverse presentations. Over time, our group noticed that a blood flush of the liver graft via a caval vent (in addition to a standard chilled flush via the portal vein) appeared to result in a milder reperfusion effect. Attenuation of PRS via caval vent seemed to minimize hemodynamic instability and reduce metabolic derangements associated with reperfusion. MATERIAL AND METHODS This was a prospective observational pilot study of standard practice with the addition of lab values and hemodynamic evaluations. We methodically observed normal clinical flow in 20 adult orthotopic liver transplant recipients. We analyzed blood and fluid samples at set time intervals during the peri-reperfusion phase. RESULTS Sixteen out of 20 patients received a blood flush via caval venting. Mean arterial pressure (MAP) and heart rate were better preserved in the patient population that received a caval blood flush vent. Elevations in central venous pressure (CVP) were similar between the 2 groups. Lab values (blood gas, electrolyte, and hemoglobin) of the patients' blood were similar, with no notable differences. Analysis of the initial blood flushed through the liver graft proved to be hypothermic, acidotic, and hyperkalemic. CONCLUSIONS Pre-reperfusion caval venting in liver transplantation (in addition to a portal vent and a chilled LR/albumin portal flush solution) appears to have favorable hemodynamic effects. The literature on this technique is sparse and larger studies are needed.

Specific BK Channel Activator NS11021 Protects Rat Renal Proximal Tubular Cells from Cold Storage-Induced Mitochondrial Injury In Vitro

Kidneys from deceased donors used for transplantation are placed in cold storage (CS) solution during the search for a matched recipient. However, CS causes mitochondrial injury, which may exacerbate renal graft dysfunction. Here, we explored whether adding NS11021, an activator of the mitochondrial big-conductance calcium-activated K⁺ (mitoBK) channel, to CS solution can mitigate CS-induced mitochondrial injury. We used normal rat kidney proximal tubular epithelial (NRK) cells as an in vitro model of renal cold storage (18 h) and rewarming (2 h) (CS + RW). Western blots detected the pore-forming α subunit of the BK channel in mitochondrial fractions from NRK cells. The fluorescent K⁺-binding probe, PBFI-AM, revealed that isolated mitochondria from NRK cells exhibited mitoBK-mediated K⁺ uptake, which was impaired ~70% in NRK cells subjected to CS + RW compared to control NRK cells maintained at 37 °C. Importantly, the addition of 1 μM NS11021 to CS solution prevented CS + RW-induced impairment of mitoBK-mediated K⁺ uptake. The NS11021–treated NRK cells also exhibited less cell death and mitochondrial injury after CS + RW, including mitigated mitochondrial respiratory dysfunction, depolarization, and superoxide production. In summary, these new data show for the first time that mitoBK channels may represent a therapeutic target to prevent renal CS-induced injury.

New Techniques for Optimization of Donor Lungs/Hearts

Injuries sustained by donor heart and lung allografts during the transplantation process are multiple and cumulative. Optimization of allograft function plays an essential role in short- and long-term outcomes after transplantation. Therapeutic targets to prevent or attenuate injury are present in the donor, the preservation process, during transplantation, and in postoperative management of the recipient. The newest and most promising methods of optimizing donor heart and lung allografts are found in alternative preservation strategies, which enable functional assessment of donor organs and provide a modality to initiate therapies for injured allografts or prevent injury during reperfusion in recipients.

Anaesthetic management of organ transplant patients

In this paper we will describe anaesthetic management of solid organ and reconstructive transplantation (RT) patients. We will focus on similar underlying principles of reperfusion, ischaemic-reperfusion injury, preconditioning and extracorporeal donor organ preservation. Special concerns for anaesthetic management of these patients need to focus on pre-assessment, pre-operative optimisation, vascular access, fluid management, blood and products replacement, cardiovascular monitoring, use of inotropes and vasoconstrictors, maintaining electrolyte balance and regional anaesthesia. Despite the complexity and long duration of transplant procedures, fast-tracking to the surgical ward after transplantation is becoming more popular and its benefits are well recognised.

Predictor parameters of liver viability during porcine normothermic ex situ liver perfusion in a model of liver transplantation with marginal grafts

Normothermic ex situ liver perfusion (NEsLP) offers the opportunity to assess biomarkers of graft function and injury. We investigated NEsLP parameters (biomarkers and markers) for the assessment of liver viability in a porcine transplantation model. Grafts from heart-beating donors (HBD), and from donors with 30 minutes (donation after cardiac death [DCD]30'), 70 minutes (DCD70'), and 120 minutes (DCD120') of warm ischemia were studied. The HBD, DCD30', and DCD70'-groups had 100% survival. In contrast, 70% developed primary nonfunction (PNF) and died in the DCD120'-group. Hepatocellular function during NEsLP showed low lactate (≤1.1 mmol/L) in all the groups except the DCD120'-group (>2 mmol/L) at 4 hours of perfusion (P = .04). The fold-urea increase was significantly lower in the DCD120'-group (≤0.4) compared to the other groups (≥0.65) (P = .01). As for cholangiocyte function, bile/perfusate glucose ratio was significantly lower (<0.6) in all the groups except the DCD120'-group (≥0.9) after 3 hours of perfusion (<0.01). Bile/perfusate Na+ ratio was significantly higher (≥1.2) after 3 hours of perfusion in all the groups except for the DCD120'-group (≤1) (P < .01). Three hours after transplantation, the DCD120'-group had a significantly higher international normalized ratio (>5) compared to the rest of the groups (≤1.9) (P = .02). Rocuronium levels were higher at all the time-points in the animals that developed PNF during NEsLP and after transplantation. This study demonstrates that biomarkers and markers of hepatocellular and cholangiocyte function during NEsLP correlate with the degree of ischemic injury and posttransplant function.

Myocardial Connective Tissue Alterations

There is a complex network of collagen throughout the heart. It is composed of a hierarchy of fibrils and fibers ranging from 10 nm to 2–3 microns in diameter. This network can be broken down by ischemia, adriamycin administration, or disulfide administration in laboratory animals. Following loss due to coronary artery ligation, the ischemic area begins bulging within 3 h. General loss of portions of the collagen matrix is induced by intravenous oxidizing glutathione, and results in marked diffuse ventricular dilatation. Generalized collagen loss in the ventricles, as induced by disulfide administration or adriamycin infusion, persists for 6 months at which time evidence of some replacement is visible, and evidence of diffuse fibrosis is present. In humans, cardiac dilatation occurs in a variety of disease states without overstretch of sarcomeres. This presumes rearrangement of the muscle bundles, which can only occur with marked alterations of the collagen matrix. Ventricular dilatation, associated with viral myocarditis or puerperal cardiomyopathy, may persist for months, suggesting the collagen loss, as with the experimental animals, takes many months to repair. The cardiac dilatation may ameliorate, or, in some patients, deteriorate into heart failure. The animal experiments with loss of the collagen matrix, ventricular dilatation, and failure to replace the matrix for many months provide an explanation for persistent cardiac dilatation in various human diseases.

Hypothermia and nutrient deprivation alter viability of human adipose-derived mesenchymal stem cells

PURPOSE

Adipose-derived mesenchymal stem cells (MSCs) are attractive biological agents in regenerative medicine. To optimize cell therapies, it is necessary to determine the most effective delivery method for MSCs. Therefore, we evaluated the biological properties of MSCs after exposure to various temperatures to define optimal storage conditions prior to therapeutic delivery of MSCs.

DESIGN

Prospective observational study.

METHODS AND MATERIALS

Adherent and non-adherent MSCs were incubated at multiple temperatures (i.e., 4, 23 and 37 °C) in Lactated Ringers (LR) solution lacking essential cell growth ingredients, or in culture media which is optimized for cell growth. Cells were assessed either after the temperature changes (4 h) or after recovery (24 h). Metabolic activity of MSCs, cell number and expression of representative mRNA biomarkers were evaluated to assess the biological effects of temperature. We monitored changes in mRNAs expression related to cytoprotective- or stress-related responses (e.g., FOS, JUN, ATF1, ATF4, EGR1, EGR2, MYC), proliferation (e.g., HIST2H4, CCNB2), and extracellular matrix production (ECM; e.g., COL3A1, COL1A1) by quantitative real time reverse-transcriptase polymerase chain reaction (RT-qPCR) analysis.

RESULTS

Our study demonstrates that storing MSCs in Lactated Ringers (LR) solution for 4 h decreases cell number and metabolic activity. The number of viable MSCs decreased significantly when cultured at physiological temperature (37 °C) and severe hypothermia (4 °C), while cells grown at ambient temperature (23 °C) exhibited the least detrimental effects. There were no appreciable biological differences in mRNA markers for proliferation or ECM deposition at any of the temperatures. However, biomarkers related to cytoprotective- or stress-responses were selectively elevated depending on temperature or media type (i.e., LR versus standard media).

CONCLUSION

The biological impact of nutrient-free media and temperature changes after 4 h exposure persists after a 24 h recovery period. Hence, storage temperature and media conditions should be optimized to improve effective dosing of MSCs.

Primary graft dysfunction after heart transplantation: a thorn amongst the roses

Primary graft dysfunction (PGD) remains the leading cause of early mortality post-heart transplantation. Despite improvements in mechanical circulatory support and critical care measures, the rate of PGD remains significant. A recent consensus statement by the International Society of Heart and Lung Transplantation (ISHLT) has formulated a definition for PGD. Five years on, we look at current concepts and future directions of PGD in the current era of transplantation.

Preservation Solutions for Kidney Transplantation: History, Advances and Mechanisms

Solid organ transplantation was one of the greatest medical advances during the past few decades. Organ preservation solutions have been applied to diminish ischemic/hypoxic injury during cold storage and improve graft survival. In this article, we provide a general review of the history and advances of preservation solutions for kidney transplantation. Key components of commonly used solutions are listed, and effective supplementations for current available preservation solutions are discussed. At cellular and molecular levels, further insights were provided into the pathophysiological mechanisms of effective ingredients against ischemic/hypoxic renal injury during cold storage. We pay special attention to the cellular and molecular events during transplantation, including ATP depletion, acidosis, mitochondrial dysfunction, oxidative stress, inflammation, and other intracellular mechanisms.

Renal temperature reduction progressively favors mitochondrial ROS production over respiration in hypothermic kidney preservation

BACKGROUND

Hypothermia, leading to mitochondrial inhibition, is widely used to reduce ischemic injury during kidney preservation. However, the exact effect of hypothermic kidney preservation on mitochondrial function remains unclear.

METHODS

We evaluated mitochondrial function [i.e. oxygen consumption and production of reactive oxygen species (ROS)] in different models (porcine kidney perfusion, isolated kidney mitochondria, and HEK293 cells) at temperatures ranging 7-37 °C.

RESULTS

Lowering temperature in perfused kidneys and isolated mitochondria resulted in a rapid decrease in oxygen consumption (65% at 27 °C versus 20% at 7 °C compared to normothermic). Decreased oxygen consumption at lower temperatures was accompanied by a reduction in mitochondrial ROS production, albeit markedly less pronounced and amounting only 50% of normothermic values at 7 °C. Consequently, malondialdehyde (a marker of ROS-induced lipid peroxidation) accumulated in cold stored kidneys. Similarly, low temperature incubation of kidney cells increased lipid peroxidation, which is due to a loss of ROS scavenging in the cold.

CONCLUSIONS

Lowering of temperature highly affects mitochondrial function, resulting in a progressive discrepancy between the lowering of mitochondrial respiration and their production of ROS, explaining the deleterious effects of hypothermia in transplantation procedures. These results highlight the necessity to develop novel strategies to decrease the formation of ROS during hypothermic organ preservation.

Low-dose In Situ Perfusion With Euro-Collins Solution Is Effective for the Procurement of Marginal Kidney Grafts From Donation After Circulatory Death Donors

We have adopted a modified method to resuscitate kidneys from donation after circulatory death (DCD) donors with the use of Euro-Collins (EC) solution instead of University of Wisconsin solution. This study aimed to evaluate kidney transplantation (KTx) outcomes of DCD procured with low-dose in situ perfusion using EC solution.

PATIENTS AND METHODS

KTx was performed in 8 adults. Kidney grafts were procured following in situ perfusion with approximately 1 L of EC solution and preserved in the solution. The kidney donor profile index value was 88% ± 21%. The terminal creatinine level of the donors was 5.5 ± 3.4 mg/dL. Of the 8 donors, 6 experienced oligoanuria prior to graft procurement.

RESULTS

The mean age of the recipients and the hemodialysis vintage were 50 ± 10 years and 161 ± 25 months, respectively. The warm and cold ischemic times were 8.3 ± 7.9 minutes and 8.7 ± 4.3 hours, respectively. All grafts functioned after a delayed graft function of 10.6 ± 6.9 days (2-25 days). There was neither immediate graft function nor primary nonfunction. The patient and graft survivals were both 100% with a terminal creatinine level of 1.3 ± .5 mg/dL.

CONCLUSIONS

Kidney grafts procured from DCD donors with a high kidney donor profile index value demonstrated good renal function with an excellent midterm outcome. Low-dose in situ perfusion with EC solution is effective for the procurement of marginal kidney grafts from DCD donors under optimal conditions such as a relatively shorter preservation time.

New Approaches to Cryopreservation of Cells, Tissues, and Organs

In this concept article, we outline a variety of new approaches that have been conceived to address some of the remaining challenges for developing improved methods of biopreservation. This recognizes a true renaissance and variety of complimentary, high-potential approaches leveraging inspiration by nature, nanotechnology, the thermodynamics of pressure, and several other key fields. Development of an organ and tissue supply chain that can meet the healthcare demands of the 21st century means overcoming twin challenges of (1) having enough of these lifesaving resources and (2) having the means to store and transport them for a variety of applications. Each has distinct but overlapping logistical limitations affecting transplantation, regenerative medicine, and drug discovery, with challenges shared among major areas of biomedicine including tissue engineering, trauma care, transfusion medicine, and biomedical research. There are several approaches to biopreservation, the optimum choice of which is dictated by the nature and complexity of the tissue and the required length of storage. Short-term hypothermic storage at temperatures a few degrees above the freezing point has provided the basis for nearly all methods of preserving tissues and solid organs that, to date, have proved refractory to cryopreservation techniques successfully developed for single-cell systems. In essence, these short-term techniques have been based on designing solutions for cellular protection against the effects of warm and cold ischemia and basically rely upon the protective effects of reduced temperatures brought about by Arrhenius kinetics of chemical reactions. However, further optimization of such preservation strategies is now seen to be restricted. Long-term preservation calls for much lower temperatures and requires the tissue to withstand the rigors of heat and mass transfer during protocols designed to optimize cooling and warming in the presence of cryoprotective agents. It is now accepted that with current methods of cryopreservation, uncontrolled ice formation in structured tissues and organs at subzero temperatures is the single most critical factor that severely restricts the extent to which tissues can survive procedures involving freezing and thawing. In recent years, this major problem has been effectively circumvented in some tissues by using ice-free cryopreservation techniques based upon vitrification. Nevertheless, despite these promising advances there remain several recognized hurdles to be overcome before deep-subzero cryopreservation, either by classic freezing and thawing or by vitrification, can provide the much-needed means for biobanking complex tissues and organs for extended periods of weeks, months, or even years. In many cases, the approaches outlined here, including new underexplored paradigms of high-subzero preservation, are novel and inspired by mechanisms of freeze tolerance, or freeze avoidance, in nature. Others apply new bioengineering techniques such as nanotechnology, isochoric pressure preservation, and non-Newtonian fluids to circumvent currently intractable problems in cryopreservation.

Organ Preservation into the 2020s: The Era of Dynamic Intervention

Organ preservation has been of major importance ever since transplantation developed into a global clinical activity. The relatively simple procedures were developed on a basic comprehension of low-temperature biology as related to organs outside the body. In the past decade, there has been a significant increase in knowledge of the sequelae of effects in preserved organs, and how dynamic intervention by perfusion can be used to mitigate injury and improve the quality of the donated organs. The present review focuses on (1) new information about the cell and molecular events impacting on ischemia/reperfusion injury during organ preservation, (2) strategies which use varied compositions and additives in organ preservation solutions to deal with these, (3) clear definitions of the developing protocols for dynamic organ perfusion preservation, (4) information on how the choice of perfusion solutions can impact on desired attributes of dynamic organ perfusion, and (5) summary and future horizons.

Organ preservation solutions: linking pharmacology to survival for the donor organ pathway

PURPOSE OF REVIEW

To provide an understanding of the scientific principles, which underpinned the development of organ preservation solutions, and to bring into context new strategies and challenges for solution development against the background of changing preservation technologies and expanded criteria donor access.

RECENT FINDINGS

Improvements in organ preservation solutions continue to be made with new pharmacological approaches. New solutions have been developed for dynamic perfusion preservation and are now in clinical application. Principles defining organ preservation solution pharmacology are being applied for cold chain logistics in tissue engineering and regenerative medicine.

SUMMARY

Organ preservation solutions support the donor organ pathway. The solution compositions allow additives and pharmacological agents to be delivered direct to the target organ to mitigate preservation injury. Changing preservation strategies provide further challenges and opportunities to improve organ preservation solutions.

Thermodynamic Theory and Experimental Validation of a Multiphase Isochoric Freezing Process

Freezing of the aqueous solutions that comprise biological materials, such as isotonic physiological saline, results in the formation of ice crystals and the generation of a hypertonic solution, both of which prove deleterious to biological matter. The field of modern cryopreservation, or preservation of biological matter at subfreezing temperatures, emerged from the 1948 discovery that certain chemical additives such as glycerol, known as cryoprotectants, can protect cells from freeze-related damage by depressing the freezing point of water in solution. This gave rise to a slew of important medical applications, from the preservation of sperm and blood cells to the recent preservation of an entire liver, and current cryopreservation protocols thus rely heavily on the use of additive cryoprotectants. However, high concentrations of cryoprotectants themselves prove toxic to cells, and thus there is an ongoing effort to minimize cryoprotectant usage while maintaining protection from ice-related damage. Herein, we conceive from first principles a new, purely thermodynamic method to eliminate ice formation and hypertonicity during the freezing of a physiological solution: multiphase isochoric freezing. We develop a comprehensive thermodynamic model to predict the equilibrium behaviors of multiphase isochoric systems of arbitrary composition and validate these concepts experimentally in a simple device with no moving parts, providing a baseline from which to design tailored cryopreservation protocols using the multiphase isochoric technique.

Oxygen Consumption by Warm Ischemia-Injured Porcine Kidneys in Hypothermic Static and Machine Preservation

Static cold storage (SCS) and hypothermic machine perfusion (HMP) are currently standard methods for renal grafts clinical preservation. Both methods are predominantly implemented without the active delivery of oxygen, even for donation after circulatory death-like kidneys. However, even under severe hypothermia (4°C-6°C), kidneys can consume oxygen and produce ATP. What is not established, though, is to what extent and how SCS and HMP compare in terms of oxygen. Using a porcine preclinical model of renal warm ischemia (WI) to compare SCS and HMP methods, we continuously monitored and quantified oxygen level and consumption along preservation; we also determined prepreservation and postpreservation cortical ATP level; values were given as median and [min; max] range. One-hour WI reduced ATP by ∼90% (from 3.3 [1.7; 4.5] mmol/L tissue in Controls). Oxygen consumption (QO₂, μmol/min per 100 g) was determined from initial solution PO₂ decrease (SCS and HMP) and from arterio-venous difference (HMP). In SCS and HMP, PO₂ decreased rapidly (t_1/2 ∼1 h) from atmospheric levels to 52.9 [38.0; 65.9] and 8.2 [3.0, 16.0] mmHg, respectively. In HMP, QO₂ was 2.7 [0.4; 3.9] versus 0.5 [0.0; 1.3] in SCS (P < 0.05); postpreservation ATP amounted to 5.8 [3.2; 6.5] in HMP versus 0.1 [0.0; 0.2] in SCS. Despite hypothermic conditions in SCS or HMP, donation after circulatory death-like renal grafts require oxygen. Increased oxygen consumption, restored ATP level, and improved histological profile in HMP might explain the established HMP superiority over SCS. These results establish a rational basis for the use of oxygen in hypothermic preservation. Optimal levels required for preservation and graft-type variants remain to be determined.

Bioengineering approaches to organ preservation ex vivo

IMPACT STATEMENT

Over the past several decades, ex vivo perfusion has emerged as a promising technology for the assessment, preservation, and recovery of donor organs. Many exciting pre-clinical findings have now been translated to clinical use, and successful transplantation following ex vivo perfusion has been achieved for heart, lung, and liver. While machine perfusion provides distinct advantages over traditional cold preservation, many challenges remain, including that of long-term (multi-day) ex vivo support. Here, we provide an overview of the current status of ex vivo machine perfusion in the pre-clinical and clinical setting and share our perspective on the future direction of the field.

Increased ENaC activity during kidney preservation in Wisconsin solution

Background

The invention of an effective kidney preservation solution capable of prolonging harvested kidney viability is the core of kidney transplantation procedure. Researchers have been working on upgrading the preservation solution quality aiming at prolonging storage time while maintaining utmost organ viability and functionality. For many years, the University of Wisconsin (UW) solution has been considered the gold standard solution for kidney preservation. However, the lifespan of kidney preservation in the UW solution is still limited. Its impact on the epithelial Na⁺ channel (ENaC) activity and its mediated processes is unknown and the primary goal of this study.

Methods

Kidneys harvested from 8 weeks old Sprague Dawley rats were divided into 4 groups depending upon the period of preservation in UW solution. Additional analysis was performed using dogs’ kidneys. ENaC activity was measured using patch clamp technique; protein expression and mRNA transcription were tested through Western blot and RT-qPCR, respectively. A colorimetric LDH level estimation was performed at different time points during UW solution preservation.

Results

Kidney preservation in Wisconsin solution caused reduction of the kidney size and weight and elevation of LDH level. ENaC activity increased in both rat and dog kidneys preserved in the UW solution as assessed by patch clamp analysis. On the contrary, ENaC channel mRNA levels remained unchanged.

Conclusions

ENaC activity is significantly elevated in the kidneys during preservation in UW solution, which might affect the immediate post-implantation allograft function and trajectory post-transplant.

Rewarming Injury after Cold Preservation

Organ dysfunction pertinent to tissue injury related to ischemic ex vivo preservation during transport from donor to recipient still represents a pivotal impediment in transplantation medicine. Cold storage under anoxic conditions minimizes metabolic activity, but eventually cannot prevent energetic depletion and impairment of cellular signal homeostasis. Reoxygenation of anoxically injured tissue may trigger additional damage to the graft, e.g., by abundant production of oxygen free radicals upon abrupt reactivation of a not yet equilibrated cellular metabolism. Paradoxically, this process is driven by the sudden restoration of normothermic conditions upon reperfusion and substantially less pronounced during re-oxygenation in the cold. The massive energy demand associated with normothermia is not met by the cellular systems that still suffer from hypothermic torpor and dys-equilibrated metabolites and eventually leads to mitochondrial damage, induction of apoptosis and inflammatory responses. This rewarming injury is partly alleviated by preceding supply of oxygen already in the cold but more effectively counteracted by an ensuing controlled and slow oxygenated warming up of the organ prior to implantation. A gentle restitution of metabolic turnover rates in line with the resumption of enzyme kinetics and molecular homeostasis improves post transplantation graft function and survival.

Cold Storage Injury to Rat Small-bowel Transplants-Beneficial Effect of a Modified HTK Solution

BACKGROUND

The small bowel is prone to ischemic injury during transport before transplantation, an injury that endangers the recipient patient. The small-bowel mucosal microcirculation in particular appears to be highly sensitive to injury. Current preservation solutions such as histidine-tryptophan-ketoglutarate (HTK) solution provide some protection to the graft. However, these were developed decades ago and do not address several critical processes, such as hypoxia-induced membrane pores and free radical-mediated hypothermic injury.

METHODS

To protect the graft from cold ischemic injury, we implemented a modified HTK solution here, including glycine, alanine, and iron chelators in a heterotopic, syngeneic small-bowel transplantation model of the rat. The effects of the modified solution and its major components were compared against the conventional HTK solution using intravital microscopy in the early reperfusion period.

RESULTS

The amino acid glycine, added to HTK solution, slightly improved mucosal perfusion. Both, the modified base solution (without iron chelators) and iron chelators increased functional capillary density of the mucosa during the early reperfusion period. The complete modified solution (with glycine, alanine, and iron chelators) significantly increased the perfusion index, functional capillary density of the mucosa, and red blood cell velocity in the grafts after reperfusion in comparison with the grafts preserved with HTK.

CONCLUSIONS

The modified preservation solution improved the microcirculation of the transplants and needs detailed evaluation in further models of small-bowel transplantation.

Rodent Skeletal Muscle Metabolomic Changes Associated With Static Cold Storage

OBJECTIVE

The aim of this study was to evaluate the impact of static cold storage preservation on skeletal muscle metabolism using a rodent model.

METHODS

Sixteen male Lewis rats (250 ± 25 g) were distributed into 4 groups, including naive control, warm ischemia for 2 hours, static warm storage for 6 hours, and static cold storage for 6 hours. Energy status, metabolomics profiling, and histopathology of the muscle were analyzed.

RESULTS

In the warm ischemia and static warm storage groups, glycolytic pathway metabolites decreased, but the Krebs cycle metabolite of succinate and the purine degradation product of hypoxanthine accumulated. Increased succinate and hypoxanthine levels were associated with increased injury severity scores. During static cold storage, the glycolytic pathway activity and the energy status were preserved. Succinate and hypoxanthine levels showed no significant difference from the naive group.

CONCLUSION

Warm ischemia results in reduced glycolysis and Krebs cycle metabolites. Static cold storage preserves the glycolytic pathway and represents a favorable contribution to cellular energy demand. Succinate and hypoxanthine might be used as novel potential biomarkers for the assessment of viability and injury severity.

Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion

The growing demand for donor organs requires measures to expand donor pool. Those include extended criteria donors, such as elderly people, steatotic livers, donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion (NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury. Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose. Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations.

A simple and static preservation system for shipping retinal pigment epithelium cell sheets

The ability to move cells and tissues from bench to bedside is an essential aspect of regenerative medicine. In this study, we propose a simple and static shipping system to deliver tissue-engineered cell sheets. Notably, this system is electronic-device-free and simplified to minimize the number of packing and opening steps involved. Shipping conditions were optimized, and application and verification of the system were performed using human iPS cell-derived or fetal retinal pigment epithelium (RPE) cell sheets. The temperature of the compartments within the insulated container was stable at various conditions, and filling up the cell vessel with medium effectively prevented turbulence-induced mechanical damage to the RPE cell sheets. Furthermore, no abnormal changes were observed in RPE morphology, transepithelial electrical resistance, or mRNA expression after transit by train and car. Taken together, our simple shipping system has the potential to minimize the costs and human error associated with bench to bedside tissue transfer. This specially designed regenerative tissue shipping system, validated for use in this field, can be used without any special training. This study provides a procedure for easily sharing engineered tissues with the goal of promoting collaboration between laboratories and hospitals and enhancing patient care.

Machine perfusion for liver transplantation in the era of marginal organs-New kids on the block

In the face of a critical organ shortage in the Western world, various strategies are employed to expand the donor pool for orthotopic liver transplantation (OLT). Among them is the transplantation of organs from extended criteria donors, a valuable source of liver allografts, however, characterized by potential risks for post-OLT complications and inferior outcomes. In recent years, machine perfusion (MP) of the explanted donor liver as well as regional perfusion techniques has witnessed significant advancements. Here, we aim to discuss different modes of dynamic organ preservation in OLT. These include hypothermic and normothermic MP, hypothermic oxygenated machine perfusion (HOPE), controlled oxygenated rewarming as well as regional perfusion protocols. Over recent years, multiple feasibility trials have demonstrated the clinical prospects of MP. In the context of OLT using organs from extended criteria donors, MP has numerous advantages compared to conventional cold storage, some of which include the preservation and reconditioning of borderline transplantable organs and the viability assessment of high-risk donor allografts. This review aims to address the topic of liver allograft MP, highlighting particularly the current trends in clinical applications and future perspectives. Furthermore, different approaches of liver storage and reconditioning are reviewed in the context of ongoing research.

Luteolin improves heart preservation through inhibiting hypoxia-dependent L-type calcium channels in cardiomyocytes

The current study aimed to evaluate whether luteolin could improve long-term heart preservation; this was achieved by evaluating the heart following long-term storage in University of Wisconsin solution (the control group) and in solutions containing three luteolin concentrations. The effects of different preservation methods were evaluated with respect to cardiac function while hearts were in custom-made ex vivo Langendorff perfusion systems. Different preservation methods were evaluated with respect to the histology, ultrastructure and apoptosis rate of the hearts, and the function of cardiomyocytes. In the presence of luteolin, the rate pressure product of the left ventricle was increased within 60 min of reperfusion following a 12-h preservation, coronary flow was higher within 30 min of reperfusion, cardiac contractile function was higher throughout reperfusion following 12- and 18-h preservations, and the left ventricle peak systolic pressure was significantly higher compared with the control group (all P<0.05). The expression levels of apoptosis regulator Bax and apoptosis regulator Bcl-2 in the luteolin groups were significantly decreased and increased, respectively. Lactate dehydrogenase, creatine kinase and malondialdehyde enzymatic activity was increased following long-term storage, while the activity of superoxide dismutase was significantly decreased. Furthermore, luteolin inhibited L-type calcium currents in ventricular myocytes under hypoxia conditions. Thus, luteolin demonstrated protective effects during long-term heart preservation in what appeared to be a dose-dependent manner, which may be accomplished through inhibiting hypoxia-dependent L-type calcium channels.

Extrapolating novel techniques utilised in solid organ transplantation to the microsurgical and vascularised composite allograft arena

Ischemia reperfusion injury (IRI) is characterised initially by restriction of oxygenated blood flow to an organ bed, resulting in tissue hypoxia and ischaemic injury, followed by further 'reperfusion' injury upon restoration of perfusion, with an influx of oxygen, inflammatory cells and generation of free radicals. The culmination is a complex interplay between cellular and biochemical processes involved in inflammation and coagulation, exhibited as the 'no re-flow' phenomenon. Under ideal circumstances, autologous free tissue transfer is performed with short ischemic times. However, there are certain clinical scenarios where the ischaemic period can be prolonged due to technical and non-technical factors. IRI is inevitable and can be possibly more pronounced in such cases. In these cases, there may be a role for plastic surgeons to adopt some of the anti-ischaemia reperfusion injury (IRI) practices used in solid organ transplantation (SOT). Knowledge of the current trends in SOT IRI reduction should be discussed by plastic surgeons to assess whether certain facets can be extrapolated into the plastic and reconstructive armamentarium. These can be applicable to more challenging microsurgical cases, including composite free tissue transfer. Three important aspects are discussed further in this editorial: (1) cold flushing, (2) machine perfusion and pharmacological manipulation. Ongoing research will need to study the impact these potential interventions will have on the acute complications but also in which subset of patients they would be most beneficial. This area is novel and exciting but cautious implementation is advised with careful scrutiny of future data.

Preservation of Blood Vessels with an Oxygen Generating Composite

Damage caused by oxygen deficiency (hypoxia) is one of the major factors limiting tissue and organ preservation time. Cooling tissues slows down metabolic rate of cells thereby prolonging tissue and organ survival sufficiently to allow transport and transplantation within a few hours. Although metabolism is slowed, cells and some enzymes continue to consume oxygen that can render cold stored tissues hypoxic. Here, an oxygen-generating composite (OGC) with sustained oxygen release is reported for ex vivo blood vessel preservation. Aorta segments are cultured under hypothermia for 25 days in vascular preservation media. The presence of OGC increases cell viability from 9 ± 6% to 96 ± 3% and retains 65 ± 8% of original KCl stimulated contractile force after 25 days compared with 25 ± 4% in controls. Culture for 7 days in nitrogen demonstrates proof-of-concept for normothermic blood vessel preservation, OGC increases the cell viability from 45 ± 15% to 78 ± 2%, and KCl stimulates contractile force from 49 ± 7% to 95 ± 8%, respectively. Oxygen release materials then may have a role in augmenting current preservation techniques.

Proteome variation of the rat liver after static cold storage assayed in an ex vivo model

Cold storage is a common procedure for liver preservation in a transplant setting. However, during cold ischemia, the liver suffers molecular alterations that can affect its performance. Also, deleterious mechanisms set forth in the storage phase are exacerbated during reperfusion. This study aimed to identify liver proteins associated with injury during cold storage and/or normothermic reperfusion using the isolated perfused rat liver model. Livers from male rats were subjected to either (1) cold storage for 24 h, (2) ex vivo normothermic reperfusion for 90 min or (3) cold storage for 24 h followed by ex vivo normothermic reperfusion for 90 min. Then, the livers were homogenized and proteins were extracted. Protein expression between each experimental group and the control (freshly resected livers) was compared by two-dimensional (2D) gel electrophoresis. Protein identification was carried out by matrix-assisted laser desorption/ionization time-of-flight spectrometry (MALDI-TOF/TOF) using MASCOT as the search engine. 23 proteins were detected with significantly altered levels of expression among the different treatments, including molecular chaperones, antioxidant enzymes, and proteins involved in energy metabolism. Some of them have been postulated as biomarkers for liver damage while others had been identified in other organs subjected to ischemia and reperfusion injury. The whole data set will be a useful resource for studying deleterious molecular mechanisms that result in diminished liver function during storage and subsequent reperfusion.

Non-invasive assessment of liver quality in transplantation based on thermal imaging analysis

BACKGROUND AND OBJECTIVE

Liver quality evaluation is one of the vital steps for predicting the success of liver transplantation. Current evaluation methods, such as biopsy and visual inspection, which are either invasive or lack of consistent standards, provide limited predictive value of long-term transplant viability. Objective analytical models, based on the real-time infrared images of livers during perfusion and preservation, are proposed as novel methods to precisely evaluate donated liver quality.

METHODS

In this study, by using principal component analysis to extract infrared image features as predictors, we construct a multivariate logistic regression model for single liver quality evaluation, and a multi-task learning logistic regression model for cross-liver quality evaluation.

RESULTS

The single liver quality predictions show testing errors of 0%. The leave-one-liver-out predictions show testing errors ranging from 9% to 36%.

CONCLUSIONS

It is found that there is a strong correlation between the viability of livers and the infrared image features in both single liver and cross-liver quality evaluations. These analytical methods also determine that the selected significant infrared image features indicate regional difference in viability and show that more stringent pre-implantation evaluation may be needed to predict transplant outcomes.

Normothermic ex-vivo liver perfusion: where do we stand and where to reach?

Nowadays liver transplantation is considered as the treatment of choice, however, the scarcity of suitable donor organs limits the delivery of care to the end-stage liver disease patients leading to the death while on the waiting list. The advent of ex-situ normothermic machine perfusion (NMP) has emerged as an alternative to the standard organ preservation technique, static cold storage (SCS). The newer technique promises to not only restore the normal metabolic activity but also attempt to recondition the marginal livers back to the pristine state, which are otherwise more susceptible to ischemic injury and foster the poor post-transplant outcomes. Areas covered: An extensive search of all the published literature describing the role of NMP based device in liver transplantation as an alternative to SCS was made on MEDLINE, EMBASE, Cochrane, BIOSIS, Crossref, Scopus databases and clinical trial registry on 10 May 2018. Expert commentary: The main tenet of NMP is the establishment of the physiological milieu, which permits aerobic metabolism to continue through out the period of preservation and limits the effects of ischemia-reperfusion (I/R) injury. In addition, by assessing the various metabolic and synthetic parameters the viability and suitability of donor livers for transplantation can be determined. This important technological advancement has scored satisfactorily on the safety and efficacy parameters in preliminary clinical studies. The present review suggests that NMP can offer the opportunity to assess and safely utilize the marginal donor livers if deemed appropriate for the transplantation. However, ongoing trials will determine its full potential and further adoption.

The Helsinki approach to face transplantation

AIM

We herein describe the establishment of the Helsinki Vascularized Composite Allotransplantation (VCA) program and its execution in the first two face transplant cases.

METHODS & PATIENTS

The Helsinki VCA program initially required the fulfillment of legal, hospital, financial, and ethical requirements. Thereafter, the assembling of a multidisciplinary team commenced. A team of Plastic, maxillofacial and ENT surgeons comprise the facial VCA team. The protocol involves collaboration with the Solid Organ Transplant (SOT) team, transplant immunology, immunosuppression, microbiology, psychiatric evaluation, well-defined VCA indications and informed consent. Between 2011 and 2017 two patients were selected for transplantation. Both patients had a severe composite facial deformity involving the maxilla and mandible following earlier ballistic injury.

RESULTS

Patient 1 was a 35 year-old male who underwent successful near total face transplantation in February 2016 and at 30 months he has a good aesthetic outcome with symmetrical restoration of the central face and good sensory and symmetrical motor functional outcomes. Patient 2 was a 58 year-old male who underwent full face transplantation in March 2018 and at 5 months he has recovered without major problems.

CONCLUSION

A successful facial VCA program requires a well-prepared research protocol, experts from multiple specialties and careful patient selection. The establishment of the Helsinki VCA program required long and thorough planning and resulted in the first two Nordic face transplantation cases. This protocol now forms the platform (as a proof of concept) for other types of vascularized composite allotransplantations.

Aldehyde Dehydrogenase 2 (ALDH2) in Rat Fatty Liver Cold Ischemia Injury

Institut George Lopez-1 (IGL-1) and Histidine-tryptophan-ketoglutarate (HTK) solutions are proposed as alternatives to UW (gold standard) in liver preservation. Their composition differs in terms of the presence/absence of oncotic agents such as HES or PEG, and is decisive for graft conservation before transplantation. This is especially so when fatty (steatotic) livers are used since these grafts are more vulnerable to ischemia insult during conservation. Their composition determines the extent of the subsequent reperfusion injury after transplantation. Aldehyde dehydrogenase-2 (ALDH2), a mitochondrial enzyme, has been reported to play a protective role in warm ischemia-reperfusion injury (IRI), but its potential in fatty liver cold ischemic injury has not yet been investigated. We evaluated the relevance of ALDH2 activity in cold ischemia injury when fatty liver grafts from Zucker Obese rats were preserved in UW, HTK, and IGL-1 solutions, in order to study the mechanisms involved. ALDH2 upregulation was highest in livers preserved in IGL-1. It was accompanied by a decrease in transaminases, apoptosis (Caspase 3 and TUNEL assay), and lipoperoxidation, which was concomitant with the effective clearance of toxic aldehydes such as 4-hydroxy-nonenal. Variations in ATP levels were also determined. The results were consistent with levels of NF-E2 p45-related factor 2 (Nrf2), an antioxidant factor. Here we report for the first time the relevance of mitochondrial ALDH2 in fatty liver cold preservation and suggest that ALDH2 could be considered a potential therapeutic target or regulator in clinical transplantation.

Creatine-loading preserves intestinal barrier function during organ preservation

We have developed a novel, intraluminal preservation solution that is tailored to the metabolic requirements of the intestine. This organ-specific solution addresses many of the problems associated with low temperature organ storage including energy, oxidative and osmotic stresses. However, conservation of energy levels remains one of the most difficult obstacles to overcome due to the inherent sensitivity of the mucosa to ischemia. Creatine-loading has become a popular and scientifically proven method of augmenting energy reserves in athletes performing anaerobic burst work activities. We hypothesized that if we could develop a method that was able to augment cellular energy levels, the structure and function of the mucosa would be more effectively preserved. The purpose of this study was to determine if creatine-loading is a feasible and effective strategy for preserving the intestine. Our data indicate that creatine loading has significant impact on energy levels during storage with corresponding improvements in mucosal structure and function. Both of our rodent models, a) continuous perfusion for 4 h and b) a single flush with our intraluminal preservation solution supplemented with 50 mM creatine, demonstrated significant improvements in creatine phosphate, ATP, Energy Charge and ATP/AMP following cold storage (P < 0.05). Notably, after 10 h creatine phosphate was 324% greater in Creatine-treated tissues compared to Controls (P < 0.05). Preferential utilization of glutathione in the Creatine group was effective at controlling oxidative injury after 10 h storage (P < 0.05). Improvements in barrier function and electrophysiology with creatine-treatment reflected superior mucosal integrity after 10 h storage; Permeability and Transepithelial resistance measurements remained at fresh tissue values. This was in stark contrast to Control tissues in which permeability rose to >300% of fresh tissue values (P < 0.005) and transepithelial resistance dropped by 95% (P < 0.005). After 10 h storage, Park's grading of histologic injury reflected extensive villus denudation (grade 4) in control tissues compared to healthy tissue (grade 0) in the Creatine group. This study demonstrates that a strategy of creatine supplementation of our intraluminal preservation solution facilitates the preservation of the intestinal mucosa during storage.