Preservation methods for kidney and liver

Improved hypothermic short-term storage of isolated mouse islets by adding serum to preservation solutions

Preserving isolated islets at low temperature appears attractive because it can keep islet quantity comparable to freshly isolated islets. In this study, we evaluated the effect of serum as an additive to preservation solutions on islet quality after short-term hypothermic storage. Isolated mouse islets were preserved at 4°C in University of Wisconsin solution (UW) alone, UW with serum, M-Kyoto solution (MK) alone or MK with serum. We then assessed islet quantity, morphology, viability and function in vitro as well as in vivo. Islet quantity after storage in all four solutions was well maintained for up to 120 h. However, islets functioned for different duration; glucose-stimulated insulin release assay revealed that the duration was 72 h when islets were stored in UW with serum and MK with serum, but only 24 h in UW alone, and the islet function disappeared immediately in MK alone. Viability assay confirmed that more than 70% islet cells survived for up to 48 h when islets are preserved in UW with serum and MK with serum, but the viability decreased rapidly in UW alone and MK alone. In in vivo bioassays using 48-h preserved isogeneic islets, all recipient mice restored normal blood glucose concentrations by transplants preserved in UW with serum or MK with serum, whereas 33.3% recipients and no recipient restored diabetes by transplants preserved in UW alone and in MK alone respectively. Adding serum to both UW and MK improves their capability to store isolated islets by maintaining islet functional viability.

Influence of trace elements on stabilization of aqueous solutions of ascorbic acid

Together with vitamin C, zinc, selenium, manganese, and magnesium play a vital role in the preservation of organs scheduled for transplantation. In the present study, it is shown that addition of 1 mg/l of these elements influences the stability of 0.3 mM ascorbic acid solutions. The solution's stability was estimated using an accelerated stability test. The concentration of vitamin C was measured using a validated spectrophotometric method, which uses the reduction of 2,6-dichlorophenoloindophenol by ascorbic acid. Elevated temperatures, the factor accelerating substances' decomposition reaction rate, were used in the tests. The research was conducted at two temperatures at intervals of 10 °C: 80 ± 0.1 and 90 ± 0.1 °C. It was stated that the studied substances' decomposition occurred in accordance with the equation for first-order reactions. The function of the logarithmic concentration (log%C) over time was revealed to be rectilinear. This dependence was used to determine the kinetics of decomposition reaction rate parameters. The stabilization of vitamin C solutions was measured as the time in which 10 % of the substance decomposed at 20 and 0 °C. Addition of Se(IV) or Mg(II) ions significantly increase the stability of ascorbic acid solution (∼34 and ∼16 %, respectively), but Zn(II) causes a significant decrease in stability by ∼23 %. Addition of Mn(II) has no significant influence on vitamin C stability.

Identifying risk factors in renal allografts before transplant: machine-measured renal resistance and posttransplant allograft survival

Enhancement of renal allograft function and survival in an era where expanded criteria donors are increasingly used requires validated selection criteria. The goal of this retrospective study was to evaluate the significance of pretransplant donor and allograft parameters to identify risk factors that can be used in a model to predict 1-year allograft outcomes. Donor demographic factors, donor type, and allograft parameters such as biopsy results and machine-measured renal resistance were correlated with 1-year graft outcome. The Kaplan-Meier method was used to estimate graft survival using the categorical predictors of donor type, donor age, and machine measured renal resistance at 1.5, 3, and 5 hours. The log-rank test was used to test the difference in survival curves between cohorts. The Cox regression analysis was used to estimate hazard ratios for machine-measured renal resistance, donor age, donor terminal creatinine level, donor's estimated glomerular filtration rate, cold ischemia time, and percent glomerulosclerosis. The data show that machine-measured renal resistance at 3 and 5 hours has a statistically significant inverse relationship to 1-year graft survival. All other risk factors had no correlation with 1-year graft survival. The machine-measured renal resistance at 3 hours is the earliest significant predictor of 1-year allograft outcome.

Flow-dependent endothelial function and kidney dysfunction

The vascular endothelium constantly integrates biomechanical and humoral signals and responds by secreting or metabolizing multiple factors that act in an autocrine or paracrine manner on the vasculature and adjacent tissues. Several studies have documented the effects of blood flow on renal endothelial cells and its effects on the pathophysiology of the kidney. In contrast, less is known about the effects of acute flow cessation on renal endothelium and kidney function. Here we review our current knowledge on flow cessation, endothelial function, and kidney dysfunction in the context of two clinically relevant settings, namely, the no-reflow phenomenon, observed during periods of renal warm ischemia, and the cold storage of kidney transplants.

Xeroprotectants for the stabilization of biomaterials

With the advancement of science and technology, it is crucial to have effective preservation methods for the stable long-term storage of biological material (biomaterials). As an alternative to cryopreservation, various techniques have been developed, which are based on the survival mechanism of anhydrobiotic organisms. In this sense, it has been found that the synthesis of xeroprotectants can effectively stabilize biomaterials in a dry state. The most widely studied xeroprotectant is trehalose, which has excellent properties for the stabilization of certain proteins, bacteria, and biological membranes. There have also been attempts to apply trehalose to the stabilization of eukaryotic cells but without conclusive results. Consequently, a xeroprotectant or method that is useful for the stable drying of a particular biomaterial might not necessarily be suitable for another one. This article provides an overview of recent advances in the use of new techniques to stabilize biomaterials and compare xeroprotectants with other more standard methods.

Ischemia-Reperfusion Injury and Ischemic-Type Biliary Lesions following Liver Transplantation

Ischemia-reperfusion (I-R) injury after liver transplantation (LT) induces intra- and/or extrahepatic nonanastomotic ischemic-type biliary lesions (ITBLs). Subsequent bile duct stricture is a significant cause of morbidity and even mortality in patients who underwent LT. Although the pathogenesis of ITBLs is multifactorial, there are three main interconnected mechanisms responsible for their formation: cold and warm I-R injury, injury induced by cytotoxic bile salts, and immunological-mediated injury. Cold and warm ischemic insult can induce direct injury to the cholangiocytes and/or damage to the arterioles of the peribiliary vascular plexus, which in turn leads to apoptosis and necrosis of the cholangiocytes. Liver grafts from suboptimal or extended-criteria donors are more susceptible to cold and warm I-R injury and develop more easily ITBLs than normal livers. This paper, focusing on liver I-R injury, reviews the risk factors and mechanisms leading to ITBLs following LT.

Whole-organ tissue engineering: decellularization and recellularization of three-dimensional matrix scaffolds

The definitive treatment for end-stage organ failure is orthotopic transplantation. However, the demand for transplantation far exceeds the number of available donor organs. A promising tissue-engineering/regenerative-medicine approach for functional organ replacement has emerged in recent years. Decellularization of donor organs such as heart, liver, and lung can provide an acellular, naturally occurring three-dimensional biologic scaffold material that can then be seeded with selected cell populations. Preliminary studies in animal models have provided encouraging results for the proof of concept. However, significant challenges for three-dimensional organ engineering approach remain. This manuscript describes the fundamental concepts of whole-organ engineering, including characterization of the extracellular matrix as a scaffold, methods for decellularization of vascular organs, potential cells to reseed such a scaffold, techniques for the recellularization process and important aspects regarding bioreactor design to support this approach. Critical challenges and future directions are also discussed.

Use of a liver from donor after cardiac death: is it appropriate for the sick or the stable?

PURPOSE OF REVIEW

Liver transplantation following donation after cardiac death (DCD) continues to be a subject for heated debate. Opinion is divided in the literature as to who benefits the most from receiving a liver from a DCD donor. This review will focus on some important questions regarding the outcome of transplantation and the selection and matching of donor and recipient.

RECENT FINDINGS

Liver transplantation with an organ from a donor after cardiac death is becoming an accepted way to treat patients on the waiting list with end-stage liver disease. However, there are still some major issues to address such as ischemic-type biliary lesions, retransplantation rates, criteria for donor and patient selection and whether conversion of donation after brain death to DCD exists. Accepting a DCD liver has the potential for reduced recipient quality of life after transplant. Death on the waiting list must be balanced against the inherent risks of a DCD liver.

SUMMARY

Success of liver transplantation is mostly measured as graft and patient survival. DCD liver transplantation is a potential tool to decrease mortality on the waiting list. Careful selection and matching of donor organ and recipient can lead to good outcomes. However, ischemic-type biliary lesions after DCD liver transplantation remain an important obstacle to overcome and have a serious impact on quality of life after transplantation.

UW is superior compared with HTK after prolonged preservation of renal grafts

BACKGROUND

In recent clinical studies, the efficacy of histidine-tryptophan-ketoglutarate (HTK) in kidney transplantation was questioned. This study compares the efficacy of University of Wisconsin (UW) and HTK solutions on transplantation outcome.

MATERIALS AND METHODS

Rat kidneys were preserved for different periods of cold ischemia (CIT). Heat capacity of the solutions, temperature of the grafts, renal function (RF), and histology were assessed before and after transplantation, respectively.

RESULTS

After prolonged CIT, recipient survival was superior in the UW - (100%) compared with the HTK group (10%). In the latter, severe tubular necrosis, DNA damage, and renal inflammation were observed, reflected by an increased KIM-1, IL6, and P-selectin expression. CIT correlated negatively with RF in both groups. RF recovered significantly faster in the UW group. LDH-release and ATP depletion after cold storage of tubular cells were lower in UW than in HTK. Heat capacity was significantly higher for UW than for HTK. Accordingly, renal temperature was lower.

CONCLUSIONS

Prolonged preservation in UW solution results in a better renal function and less tissue damage compared with HTK, possibly due to improved cooling and better cell viability of the graft. The use of HTK for renal allografts should therefore be reconsidered, particularly when CIT is expected to be long.

Organ Preservation: Current Concepts and New Strategies for the Next Decade

SUMMARY: Organ transplantation has developed over the past 50 years to reach the sophisticated and integrated clinical service of today through several advances in science. One of the most important of these has been the ability to apply organ preservation protocols to deliver donor organs of high quality, via a network of organ exchange to match the most suitable recipient patient to the best available organ, capable of rapid resumption of life-sustaining function in the recipient patient. This has only been possible by amassing a good understanding of the potential effects of hypoxic injury on donated organs, and how to prevent these by applying organ preservation. This review sets out the history of organ preservation, how applications of hypothermia have become central to the process, and what the current status is for the range of solid organs commonly transplanted. The science of organ preservation is constantly being updated with new knowledge and ideas, and the review also discusses what innovations are coming close to clinical reality to meet the growing demands for high quality organs in transplantation over the next few years.

Current protective strategies in liver surgery

During liver resection surgery for cancer or liver transplantation, the liver is subject to ischaemia (reduction in blood flow) followed by reperfusion (restoration of blood flow), which results in liver injury [ischemia-reperfusion (IR) or IR injury]. Modulation of IR injury can be achieved in various ways. These include hypothermia, ischaemic preconditioning (IPC) (brief cycles of ischaemia followed by reperfusion of the organ before the prolonged period of ischaemia i.e. a conditioning response), ischaemic postconditioning (conditioning after the prolonged period of ischaemia but before the reperfusion), pharmacological agents to decrease IR injury, genetic modulation of IR injury, and machine perfusion (pulsatile perfusion). Hypothermia decreases the metabolic functions and the oxygen consumption of organs. Static cold storage in University of Wisconsin solution reduces IR injury and has prolonged organ storage and improved the function of transplanted grafts. There is currently no evidence for any clinical advantage in the use of alternate solutions for static cold storage. Although experimental data from animal models suggest that IPC, ischaemic postconditioning, various pharmacological agents, gene therapy, and machine perfusion decrease IR injury, none of these interventions can be recommended in clinical practice. This is because of the lack of randomized controlled trials assessing the safety and efficacy of ischaemic postconditioning, gene therapy, and machine perfusion. Randomized controlled trials and systematic reviews of randomized controlled trials assessing the safety and efficacy of IPC and various pharmacological agents have demonstrated biochemical or histological improvements but this has not translated to clinical benefit. Further well designed randomized controlled trials are necessary to assess the various new protective strategies in liver resection.