Search Results (47)

Chronic kidney disease (CKD) affects over 10% of the global population, with end-stage renal disease (ESRD) necessitating renal replacement therapy. Kidney transplantation remains the optimal treatment for ESRD. However, the global donor kidney shortage crisis has led to increased reliance on deceased donor kidneys. Donors are classified as either donation after brain death (DBD) or donation after circulatory death (DCD), each associated with distinct ischemic injuries that impact graft function. Ischemia–reperfusion injury (IRI) plays a pivotal role in transplant outcomes, triggering oxidative stress, inflammation, and endothelial dysfunction. While static cold storage (SCS) remains the gold standard for organ preservation, alternative strategies such as hypothermic or normothermic machine perfusion (HMP and NMP), use of oxygen carriers during storage, and supplemental compounds to storage solutions have emerged, offering potential benefits in preserving graft viability. This review explores the cellular and molecular mechanisms of ischemic injury in deceased donor kidneys, preservation strategies tested in preclinical models, and emerging therapeutic interventions aimed at improving adverse post-transplant outcomes. Full article

Organ transplantation has significantly progressed since the 1950s, with notable advancements in surgical procedures and immunosuppression. However, current organ preservation techniques, mainly static cold storage, have not evolved at the same pace and remain insufficient to prevent ischemic and oxidative damage. This damage, primarily caused by the cessation of aerobic metabolism, limits organ viability and transplant outcomes. In this study, we investigated whether supplementing a storage solution with a hemoglobin-based oxygen carrier (HBOC) could improve the condition of ex vivo rabbit kidneys by maintaining oxygenation and supporting aerobic metabolism. In a paired, randomized design, contralateral rabbit kidneys were preserved either in a Krebs-Ringer-based solution enriched with the polymerized hemoglobin OxyVita^®C (15 g/L, p50 4–6 mmHg, MW ≈ 17 MDa, pH adjusted to 7.4) or in an HBOC-free control solution. Physicochemical characterization of OxyVita^®C included oxygen equilibrium curves, zeta potential, polydispersity index, and dynamic light scattering. Biochemical markers (AST, ALT, LDH, K⁺, pH) and histopathological assessments were used to evaluate tissue integrity over 24 h. Histology was additionally stratified according to rinsing protocols (unwashed, NaCl single flush, triple flush), and tubular necrosis was scored by blinded pathologists. Group comparisons were analyzed using ANOVA with Tukey’s HSD test. The HBOC-enriched solution showed improved tissue preservation, higher cell survivability, and better histomorphological profiles, with significantly reduced tubular necrosis scores compared to controls. These findings suggest that active oxygen delivery via HBOCs offers a promising strategy to mitigate ischemic damage during ex vivo kidney storage. Limitations include the lack of transplantation outcomes and direct ROS quantification, which will be addressed in future work integrating hypothermic and normothermic machine perfusion. Full article

Proprotein Convertase Subtilisin/Kexin type 9 PCSK9 inhibitors (PCSK9i) are a novel class of cholesterol-lowering agents that also offer protection against tissue ischemia by reducing apoptosis, pyroptosis, and myocardial infarct size. This study evaluated the effects of the PCSK9 inhibitor PEP 2-8 during hypothermic perfusion (HP) in a rat model of donation after circulatory death (DCD) kidney transplantation. DCD kidneys were perfused at 4 °C for six hours with either Perf-Gen solution alone (control) or Perf-Gen supplemented with PEP 2-8. Glucose and lactate dehydrogenase (LDH) levels were measured at baseline and after six hours (T6h). At T6h, kidneys were evaluated for ischemic injury, tubular cell proliferation, apoptosis, nitrotyrosine (N-Tyr) staining, tissue ATP and LDH levels, and gene expression of PCSK9 and NOX4. Metabolomic profiling was also performed. PEP 2-8 treatment significantly reduced PCSK9 expression, decreased tubular ischemic injury and necrosis, and lowered LDH release. Treated kidneys showed enhanced tubular cell proliferation, reduced apoptosis, and diminished oxidative stress, indicated by decreased N-Tyr staining and NOX4 expression. Energy metabolism was improved, with higher tissue ATP and glucose levels observed in the PEP 2-8 group. Metabolomic analysis further supported the antioxidant effects of PEP 2-8. This is the first study to demonstrate that PEP 2-8 administered during pre-transplant hypothermic perfusion provides renal protection by improving energy metabolism and reducing oxidative stress in the context of ischemic injury. Full article

Background and Objectives: Kidney transplantation remains the gold-standard treatment for end-stage renal disease (ESRD). For deceased donor transplantation, optimal allograft preservation represents a critical determinant of success. While static cold storage (SCS) has been the historical standard, hypothermic machine perfusion (HMP) has emerged in recent decades as a technologically advanced alternative. However, comparative data from smaller-volume centers utilizing exclusively donation after brain death (DBD) donors remain scarce. Materials and Methods: This retrospective single-center study included 94 patients who received kidney transplants from deceased DBD donors between January 2018 and December 2024. We employed a paired kidney study design where one kidney from each donor was preserved using HMP (LifePort, set at 30/20 mm Hg pressure), while the contralateral kidney was stored in SCS. Parameters compared were creatinine concentration in recipient serum after transplantation, DGF, acute rejection and hospital stay. Results: The HMP group had a significantly longer cold ischemia time (CIT) (18.09 ± 5.91 h, range: 6.5–34.0 h) compared to the SCS group (12.36 ± 5.18 h, range: 4.0–23.0 h; p < 0.005). The DGF rate was significantly lower in the HMP group (4.3%) than the SCS group (25.5%) (p = 0.004). HMP was also associated with a shorter mean hospitalization (11.81 vs. 15.66 days, p = 0.008) and superior early graft function, particularly in kidneys with CIT ≥ 18 h, which showed significantly lower serum creatinine at day 14 (124.48 vs. 164.89 µmol/L, p = 0.036). Conclusions: HMP usage in kidney transplantation decreased the possibility for DGF in DBD donors and shortened the post-op hospitalization time. It is a feasible method for kidney storage before transplantation even in a case of prolonged CIT. Full article

Despite improvements in kidney transplantation rates, the shortage of donor kidneys remains a critical issue, exacerbated by non-utilization of recovered kidneys due to quality concerns, necessitating advancements in perfusion methods to enhance graft outcomes and usage. Although static cold storage remains the default standard for kidney preservation, newer methods like hypothermic machine perfusion have shown improved outcomes, including reduced delayed graft function and better survival rates. Hypothermic oxygenated machine perfusion and normothermic machine perfusion offer some potential clinical benefits but studies to date have demonstrated mixed results. In the United States, LifePort and the XVIVO’s Kidney Assist Transport are the most popular hypothermic perfusion devices, with NMP devices mostly in trials. Combining perfusion with biomarkers such as mitochondrial flavin mononucleotide, neutrophil gelatinase-associated lipocalin, and osteopontin shows promise in assessing kidney viability and predicting post-transplant outcomes, though further research is also needed. Emphasis on repair biomarkers, such as uromodulin and osteopontin, aims to better predict graft outcomes and develop new therapies. While notable advancements have been made in the use of machine perfusion and viability testing for liver transplantation, additional research with larger sample sizes is essential to substantiate these results and enhance kidney transplantation outcomes. Full article

Organ shortage is a major challenge in transplantation, prompting the use of extended criteria donor grafts. These require improved preservation techniques and reliable methods to assess graft function. This study aimed to evaluate changes in the kidney metabolome following three preservation methods: normothermic ex vivo kidney perfusion (NEVKP), hypothermic machine perfusion (HMP) and static cold storage (SCS) in porcine autotransplant models. A chemical biopsy allowed minimally invasive sampling of metabolites, which were analyzed using liquid chromatography coupled with high-resolution mass spectrometry. The results highlighted metabolites affected by ischemia and oxidative stress in donor kidneys, as well as changes specific to each preservation method. Differences were observed immediately after transplantation and reperfusion and several days post-surgery. NEVKP was associated with the activation of physiological anti-oxidative and anti-inflammatory mechanisms, suggesting potential protective effects. However, some metabolites had dual roles, which may influence future graft treatment designs. HMP and SCS, while reducing energy demand in cells, also limit physiological repair mechanisms. These findings provide a basis for improving graft assessment and organ preservation, with chemical biopsy serving as both a tool for discovery and a potential diagnostic method for monitoring graft quality. Full article

End-stage renal disease (ESRD) is a serious and lethal disease that carries with it a high morbidity and mortality rate if left untreated. Treating ESRD is conducted via renal replacement therapy and/or kidney transplantation, with the latter being the preferred option given the better outcomes and quality of life for the patients. However, as ESRD rises in prevalence, kidney transplantation rates remain largely unchanged. In every kidney transplantation, ischemia–reperfusion injury (IRI) is inevitable and the effect this has on the kidney depends based on donor type. IRI works through a variety of molecular mechanisms, primarily mitochondrial oxidative stress and programmed cell death mechanisms. Given the urgency to ensure the best outcomes for these limited kidney transplants, there has been a continued effort to find various potential therapeutic mechanisms to counteract IRI preoperatively, intraoperatively, and postoperatively. These include hypothermic machine perfusion, ischemic conditioning, nanoparticle removal of free radicals, peptide-based therapies, microRNA, and more. There is an ongoing effort to find the best way to mitigate IRI in kidney transplantation and this is being achieved through a better understanding of the molecular mechanisms of IRI. Full article

Background: Optimizing organ preservation techniques is imperative in the face of donor kidney shortage and high waiting list mortality. Hypothermic machine perfusion (HMP) has emerged as an effective method to improve graft function post-transplantation, particularly for deceased donor kidneys, prone to ischemia reperfusion injury (IRI). The perfusion solution includes glucose to support kidney metabolism; however, its effect on mitochondrial function remains unclear. The present study investigated the effect of glucose supplementation during 24 h of oxygenated HMP on mitochondrial function in porcine kidneys. Methods: After 30 min of warm ischemia, porcine slaughterhouse kidneys were preserved for 24 h using HMP with one of the following three solutions: the standard HMP preservation solution, University of Wisconsin machine perfusion (UW-MP) solution, which contains glucose; the solution used for static cold storage, University of Wisconsin cold storage (UW-CS) solution, which lacks glucose; or the UW-CS supplemented with 10 mmol/L glucose. Tissue and perfusate samples were collected before, during, and after perfusion for further analysis. Results: ATP production, mitochondrial respiration, and oxidative stress markers were not significantly different between groups. Glucose was released into the perfusion solution even from kidneys without exogenous glucose supplementation in the perfusate. Conclusions: These results suggest that kidney mitochondrial respiration does not depend on the presence of glucose in the HMP perfusion solution at the start of perfusion, underscoring the need for further exploration of nutrient supplementation and mitochondrial function in organ preservation strategies. Full article

Kidney transplantation (KT) is the gold-standard treatment of end-stage kidney disease (ESKD). Traditional preservation methods, such as static cold storage (SCS), have been replaced by modern and more effective preservation methods, especially hypothermic machine perfusion (HMP). Regardless of improved preservation, ischemia-reperfusion injury (IRI) is inevitable, limiting graft functionality through delayed graft function (DGF) and graft survival. Supplementing the ischemic kidney graft with oxygen during hypothermic preservation has been used in different methods as an attempt to counteract IRI and its effects on graft function and survival. Various oxygenation methods have been studied, from adaptations of classic and well-known preservation strategies, like the addition of oxygen carriers to SCS, or more innovative preservation methods, like hyperbaric oxygenation or retrograde oxygen persufflation. In this review, we will attempt to provide a summary of the available evidence on oxygen carriers, hyperbaric oxygenation, the two-layer method, retrograde oxygen persufflation, and hypothermic oxygenated machine perfusion (HOPE) and discuss the effect these strategies have on kidney graft functionality. Full article

Chronic kidney disease (CKD) is a prevalent disease affecting almost 10% of the world’s population, with many cases progressing to end-stage kidney disease (ESKD). Kidney transplantation (KT) is the gold-standard treatment for ESKD. Due to growing KT waitlists, the deceased kidney donor (DKDs) criteria have expanded to increase the number of available kidney grafts. Kidney graft preservation ensures optimal graft function after KT. Static cold storage (SCS) as a preservation method is still widely used. Hypothermic machine perfusion (HMP) has proven to decrease delayed graft function (DGF) and increase graft survival. Most recent studies advocate for the use of HMP regardless of donor type. However, emerging technologies, such as hypothermic oxygenated machine perfusion (HOPE) and normothermic machine perfusion (NMP), have shown promising results in specific scenarios. This review aims to provide a summary of the well-established kidney graft preservation methods and their outcomes, as well as novel technological advances that allow for newer preservation strategies. Full article

Therapeutic measures aimed at optimising organ function prior to transplantation—whether by conditioning the donor after determination of brain death or by improving organ preservation after kidney removal—have the potential to enhance outcomes after transplantation. The particular advantage is that, unlike any optimised immunosuppressive therapy, a favourable effect can be achieved without side effects for the organ recipient. In recent years, several such measures have been tested in controlled clinical trials on large patient cohorts following kidney transplantation. Hypothermic pulsatile machine perfusion, in particular, has become the focus of interest, but interventions in the donor prior to organ removal, such as the administration of low-dose dopamine until the start of cold perfusion as an example of conditioning antioxidant therapy and therapeutic donor hypothermia in the intensive care unit after brain death confirmation, have also significantly reduced the frequency of dialysis after transplantation with far less effort and cost. With regard to benefits for graft survival, the database for all procedures is less clear and controversial. The aim of this review article is to re-evaluate the available clinical evidence from large multicentre controlled trials, which have also significantly influenced later meta-analyses, and to assess the significance for use in routine clinical practice. Full article

This study aims to determine the effectiveness of administering 80 ppm nitric oxide in reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental perfusion. Twenty-four sheep were randomized into four groups: two groups received 80 ppm NO conditioning with 90 min of cardiopulmonary bypass (CPB + NO) or 90 min of CPB and hypothermic circulatory arrest (CPB + CA + NO), while two groups received sham protocols (CPB and CPB + CA). Kidney injury was assessed using laboratory (neutrophil gelatinase-associated lipocalin, an acute kidney injury biomarker) and morphological methods (morphometric histological changes in kidney biopsy specimens). A kidney biopsy was performed 60 min after weaning from mechanical perfusion. NO did not increase the concentrations of inhaled NO₂ and methemoglobin significantly. The NO-conditioning groups showed less severe kidney injury and mitochondrial dysfunction, with statistical significance in the CPB + NO group and reduced tumor necrosis factor-α expression as a trigger of apoptosis and necroptosis in renal tissue in the CPB + CA + NO group compared to the CPB + CA group. The severity of mitochondrial dysfunction in renal tissue was insignificantly lower in the NO-conditioning groups. We conclude that NO administration is safe and effective at reducing kidney injury, mitochondrial dysfunction and regulated cell death in kidneys during experimental CPB. Full article

In transplantation, hypothermic machine perfusion (HMP) has been shown to be superior to static cold storage (SCS) in terms of functional outcomes. Ex vivo machine perfusion offers the possibility to deliver drugs or other active substances, such as Mesenchymal Stem Cells (MSCs), directly into an organ without affecting the recipient. MSCs are multipotent, self-renewing cells with tissue-repair capacities, and their application to ameliorate ischemia- reperfusion injury (IRI) is being investigated in several preclinical and clinical studies. The aim of this study was to introduce MSCs into a translational model of hypothermic machine perfusion and to test the efficiency and feasibility of this method. Methods: three rodent kidneys, six porcine kidneys and three human kidneys underwent HMP with 1–5 × 10⁶ labelled MSCs within respective perfusates. Only porcine kidneys were compared to a control group of 6 kidneys undergoing HMP without MSCs, followed by mimicked reperfusion with whole blood at 37 °C for 2 h for all 12 kidneys. Reperfusion perfusate samples were analyzed for levels of NGAL and IL-β by ELISA. Functional parameters, including urinary output, oxygen consumption and creatinine clearance, were compared and found to be similar between the MSC treatment group and the control group in the porcine model. IL-1β levels were higher in perfusate and urine samples in the MSC group, with a median of 285.3 ng/mL (IQR 224.3–407.8 ng/mL) vs. 209.2 ng/mL (IQR 174.9–220.1), p = 0.51 and 105.3 ng/mL (IQR 71.03–164.7 ng/mL) vs. 307.7 ng/mL (IQR 190.9–349.6 ng/mL), p = 0.16, respectively. MSCs could be traced within the kidneys in all models using widefield microscopy after HMP. The application of Mesenchymal Stem Cells in an ex vivo hypothermic machine perfusion setting is feasible, and MSCs can be delivered into the kidney grafts during HMP. Functional parameters during mimicked reperfusion were not altered in treated kidney grafts. Changes in levels of IL-1β suggest that MSCs might have an effect on the kidney grafts, and whether this leads to a positive or a negative outcome on IRI in transplantation needs to be determined in further experiments. Full article

Kidney transplantation is a life-saving intervention for end-stage renal disease; yet, the persistent gap between organ demand and supply remains a significant challenge. This paper explores the escalating discard rates of deceased donor kidneys in the United States to assess trends, discard reasons, demographical differences, and preservation techniques. Data from the Scientific Registry of Transplant Recipients from 2010 to 2021 was analyzed using chi-squared tests for trend significance and logistic regression to estimate odds ratios for kidney discard. Over the last decade, discard rates have risen to 25% in 2021. Most discarded kidneys came from extended criteria donor (ECD) donors and elevated kidney donor profile index (KDPI) scores. Kidney biopsy status was a significant factor and predictor of discard. Discard rates varied greatly between Organ Procurement and Transplantation Network regions. Of reasons for discard, “no recipient located” reached a high of 60%. Additionally, there has been a twofold increase in hypothermic machine perfusion (HMP) since 2010, with transportation difficulties being the main reason for the discard of perfused kidneys. Our findings suggest a need to recalibrate organ utilization strategies, optimize the use of lower-quality kidneys through advanced preservation methods, and address the evolving landscape of organ allocation policies to reduce kidney discard rates. Full article

Transplanted organs are subjected to harmful conditions through stopping blood flow, hypothermic storage of the graft, and subsequent reperfusion. In particular, kidneys donated from patients after cardiac arrest (DCD) are classified as more vulnerable to ischemia–reperfusion injury (IRI). Hypothermic machine perfusion is proposed as a solution for better kidney storage before transplantation, and it is a good platform for additional graft treatment. Antioxidants have gained interest in regenerative medicine due to their ability to scavenge reactive oxygen species (ROS), which play a key role in IRI. We evaluated the effect of Mitoquinone (MitoQ), a strong mitochondria-targeted antioxidant, administered directly to the perfusing buffer. Rat kidneys were isolated, randomly classified into one of the following groups, donation after brainstem death (DBD), DCD, and DCD with MitoQ, and perfused for 22 hours with a hypothermic machine perfusion system. Subsequently, we detected levels of kidney injury (KIM-1) and oxidative stress (ROS/RNS, cytochrome C oxidase, and mitochondrial integrity) markers. We compared the activation of the apoptosis pathway (caspase 3 and 9), the concentration of phosphorylated Akt (pAkt), and the pAkt/total Akt ratio. MitoQ reduces KIM-1 concentration, total ROS/RNS, and the level of caspases. We observed a decrease in pAkt and the pAkt/total Akt ratio after drug administration. The length of warm ischemia time negatively impacts the graft condition. However, MitoQ added to the perfusing system as an ‘on pump’ therapy mitigates injury to the kidney before transplantation by inhibiting apoptosis and reducing ROS/RNS levels. We propose MitoQ as a potential drug for DCD graft preconditioning. Full article