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Preserving organs at subzero temperatures with halted metabolic activity holds the potential to prolong preservation and expand the donor organ pool for transplant. Our group recently introduced partial freezing, a novel approach in high-subzero storage at -15 °C, enabling 5-day storage of rodent livers through precise control over ice nucleation and unfrozen fraction. However, increased vascular resistance and tissue edema suggested a need for improvements to extend viable preservation. Here, we describe an optimized partial freezing protocol with key optimizations, including an increased concentration of polyethylene glycol (PEG) to enhance membrane stability while minimizing shear stress during cryoprotectant unloading with an acclimation period and a maintained osmotic balance through an increase in bovine serum albumin (BSA). These approaches ensured the viability during preservation and recovery processes, promoting liver function and ensuring optimal preservation. This was evidenced by increased oxygen consumption, decreased vascular resistance, and edema. Ultimately, we show that using the optimized protocol, livers can be stored for 10 days with comparable vascular resistance and lactate levels to 5 days, outperforming the viability of time-matched static cold stored (SCS) livers as the current gold standard. This study represents a significant advancement in expanding organ availability through prolonged preservation, thereby revolutionizing transplant medicine., (© 2024. The Author(s).)

Recent years have witnessed significant advancements in the cryopreservation of various tissues and cells, yet several challenges persist. This review evaluates the current state of cryopreservation, focusing on contemporary methods, notable achievements, and ongoing difficulties. Techniques such as slow freezing and vitrification have enabled the successful preservation of diverse biological materials, including embryos and ovarian tissue, marking substantial progress in reproductive medicine and regenerative therapies. These achievements highlight improved post-thaw survival and functionality of cryopreserved samples. However, there are remaining challenges such as ice crystal formation, which can lead to cell damage, and the cryopreservation of larger, more complex tissues and organs. This review also explores the role of cryoprotectants and the importance of optimizing both cooling and warming rates to enhance preservation outcomes. Future research priorities include developing new cryoprotective agents, elucidating the mechanisms of cryoinjury, and refining protocols for preserving complex tissues and organs. This comprehensive overview underscores the transformative potential of cryopreservation in biomedicine, while emphasizing the necessity for ongoing innovation to address existing challenges., Competing Interests: The authors declare no conflicts of interest.

Purpose: Ischemia reperfusion injury represents a significant yet difficult to assess risk factor for short- and long-term graft impairment in human liver transplantation (LT). As a non-invasive, non-ionizing tool, hyperspectral imaging (HSI) is capable of correlating optical properties with organ microperfusion. Hence, we here performed a study of human liver allografts assessed by HSI for microperfusion and prediction of initial graft function., Methods: Images of liver parenchyma of 37 human liver allografts were acquired at bench preparation, during normothermic machine perfusion (NMP), if applicable, and after reperfusion in the recipient. A specialized HSI acquisition software computed oxygen saturation (StO2), tissue hemoglobin indices (THI), near infrared perfusion indices (NIR), and tissue water indices (TWI). HSI parameters were analyzed for differences with regard to preservation technique, reperfusion sequence and presence of early allograft dysfunction (EAD)., Results: Organ preservation was performed by means of NMP (n = 31) or static cold storage (SCS; n = 6). Patients' demographics, donor characteristics, presence of EAD (NMP 36.7% vs. SCS 50%, p = 0.6582), and HSI parameters were comparable between both groups of preservation method. In organs developing EAD, NIR at 1, 2, and 4 h NMP and after reperfusion in the recipient was significantly lower (1 h NMP: 18.6 [8.6-27.6] vs. 28.3 [22.5-39.4], p = 0.0468; 2 h NMP: 19.4 [8.7-30.4] vs. 37.1 [27.5-44.6], p = 0.0011; 4 h NMP: 26.0 [6.8-37.1] vs. 40.3 [32.3-49.9], p = 0.0080; reperfusion: 13.0 [11.5-34.3] vs. 30.6 [19.3-44.0], p = 0.0212)., Conclusion: HSI assessment of human liver allografts is feasible during organ preservation and in the recipient. NIR during NMP and after reperfusion might predict the onset of EAD. Larger trials are warranted for assessment of this novel technique in human LT., (© 2024. The Author(s).)

Optimization of donor heart preservation solutions has played a key role in reducing ischemia-reperfusion injury in donor hearts during organ retrieval, transportation, and transplantation. Previous work from our laboratory showed that the addition of glyceryl trinitrate and erythropoietin to donor heart preservation solutions could significantly improve cardiac functional recovery after prolonged cold storage and in donation after circulatory death hearts. This supplementation protocol has been implemented in clinical use in transplant units around Australia, Belgium, and the United Kingdom. Here, we outline a protocol for testing supplementation strategies using an ex vivo isolated working rat heart (IWRH) perfusion circuit. Using this methodology, supplementation strategies can be tested in the context of prolonged cold static storage, donation after brain death, and donation after circulatory death donor heart preservation. Cardiac functional recovery, measured by aortic flow, coronary flow, cardiac output, pulse pressure, and heart rate, can be used to determine whether a particular preservation strategy can minimize ischemia-reperfusion injury of the donor heart.

Importance: Despite the unmet need for donor organs, organ use from donation after circulatory determination of death (DCD) donors has been limited by inferior transplant outcomes. Normothermic regional perfusion (NRP) improves recipient outcomes and organ utilization from DCD donors. There is variability in NRP policies and experience among US organ procurement organizations (OPOs)., Objectives: To determine OPO experience, identify operational inconsistencies, and explore needs related to NRP., Design, Setting, and Participants: This survey study included 55 OPOs in the US that had recovered DCD organs and completed a survey on operational, administrative, and educational components related to NRP in November to December 2023. Data analysis was performed from February to April 2024., Main Outcome and Measures: The primary outcome was the number of OPOs participating in and/or anticipating NRP participation. Secondary outcomes were NRP implementation barriers, OPO education practices, and future needs regarding consensus NRP recommendations and standards., Results: Of 55 respondents, 11 (20%) were chief executive officers, 8 (15%) were chief operating officers, and 36 (65%) were medical directors or chief clinical officers. Forty-nine OPOs facilitated NRP cases: 26 OPOs (53%) facilitated both thoracoabdominal NRP (TA-NRP) and abdominal NRP (A-NRP) cases, 16 OPOs (33%) facilitated only TA-NRP, and 7 OPOs (14%) facilitated only A-NRP. OPOs reported 606 NRP cases (421 TA-NRP [69%], 185 A-NRP [31%]); median (range) case experience was 8 (1-52). Fifty-two of 55 OPOs (95%) thought standardized guidance documents would be helpful. All 49 OPOs facilitated NRP at a transplant center's request; 39 (80%) had NRP initiated by a nonlocal transplant center. Twenty-three of 49 OPOs (47%) participated in NRP without a policy and without a policy pending approval. Positive donor hospital feedback was received by 29 OPOs (59%), primarily focused on increased organs transplanted and prerecovery communication. Allocation challenges were experienced by 21 OPOs (43%); their median (range) case volume was higher than those with no reported allocation challenges (11 [3-52] vs 6.5 [1-29]; P = .03). Eleven OPOs (22%) had incorporated NRP into general donor hospital education., Conclusions: In this survey study of US OPOs, wide variation existed with respect to NRP experience and practice. Allocation challenges occurred more frequently with increased NRP experience. NRP guidelines and standardization were desired by most OPOs to decrease allocation challenges and maximize the gift of organ donation.

Background: Hypothermic Oxygenated machine PErfusion (HOPE) can reduce ischemic reperfusion injury and improve outcomes for liver transplant recipients. However, the effect of HOPE on high-risk extended criteria donor (ECD) and donation after circulatory death determination (DCDD) grafts is incomplete, despite the expectation that this cohort benefit maximally from HOPE. Accordingly, this paper aims to characterize the effect of HOPE on ECD and DCDD grafts., Methods: This study includes all papers comparing HOPE to static cold storage for high-risk ECD and DCDD grafts. Systematic searches of Medline, Embase, and Scopus were completed using the terms "HOPE" OR "hypothermic oxygenated machine perfusion" AND "liver transplantation". Data were extracted and analyzed using IBM SPSS to perform the meta-analysis., Results: A total of 2286 records were identified, with 10 meeting the inclusion criteria. Overall, the quality of evidence is heterogenous with many papers relying on retrospective controls. However, pooled analysis demonstrates HOPE to significantly reduce the rate of early allograft dysfunction, 12-month graft failure, re-transplantation, total biliary complications, and non-anastomotic strictures for high-risk grafts., Conclusions: There is good evidence that HOPE improves outcomes following liver transplantation across a number of biochemical and clinical endpoints for high-risk grafts. Of note, the reduction in biliary complications and re-transplantation is particularly significant given the morbidity associated with these endpoints. However, further, high-quality prospective trials with contemporary controls and clinically relevant primary endpoints are needed to better define the impact of HOPE for this cohort of grafts., (© 2024 The Author(s). Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Competing Interests: The authors declare no funding or conflicts of interest.

Background: A better understanding of the molecular events during liver normothermic machine perfusion (NMP) is warranted to develop a data-based approach for the identification of biomarkers representative of graft quality and posttransplant outcome. We analysed the dynamic transcriptional changes during NMP and linked them to clinical and biochemical parameters., Methods: 50 livers subjected to NMP for up to 24 h were enrolled. Bulk RNA sequencing was performed in serial biopsies collected pre and during NMP, and after reperfusion. Perfusate was sampled to monitor liver function. qPCR and immunohistochemistry were performed to validate findings. Molecular profiles were compared between transplanted and non-transplanted livers, and livers with and without early allograft dysfunction., Findings: Pathways related to immune and cell stress responses, cell trafficking and cell regulation were activated during NMP, while cellular metabolism was downregulated over time. Anti-inflammatory responses and genes involved in tissue remodelling were induced at later time-points, suggesting a counter-response to the immediate damage. NMP strongly induced a gene signature associated with ischemia-reperfusion injury. A 7-gene signature corresponds with the benchmarking criteria for transplantation or discard at 6 h NMP (area under curve 0.99). CD274 gene expression (encoding programmed cell-death ligand-1) showed the highest predictive value. LEAP2 gene expression at 6 h NMP correlated with impaired graft function., Interpretation: Assessment of gene expression markers could serve as a reliable tool to evaluate liver quality during NMP and predicts early graft function after transplantation., Funding: The research was supported by "In Memoriam Dr. Gabriel Salzner Stiftung", Tiroler Wissenschaftsfond, Jubiläumsfonds-Österreichische Nationalbank and MUI Start grant., Competing Interests: Declaration of interests SS received consulting fees, honoraria for lectures or travel support from the following entities, not related to the present study: Merck, Atara, Nefro Health, ITB, iCoat Medical, Dialectica, Johnson & Johnson, Sanofi, OrganOx, Chiesi, Astra Zenica, XVIVO, Intuitive, Takeda. SS received an EP-Patent not related to this study (23150338.4). SS is member of the DSMB of the following study: Statins for Improving orGaN outcomE in Transplantation (SIGNET) Trial, and in the following Trial Boards: Trial Steering Committee Chair: Perfused, Liver, Utilization Study (PLUS Study), NHS, UK. The other authors have no potential conflict of interest to report., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Background: Reliable 24-hour preservation is required to optimize the rehabilitation potential of Ex Situ Lung Perfusion (ESLP). Other ESLP protocols include fresh perfusate replacement to counteract an accumulation of deleterious by-products. We describe the results of our reliable 24-hour negative pressure ventilation (NPV)-ESLP protocol with satisfactory acute post-transplant outcomes and investigate perfusate exchange (PE) as a modification to enhance prolonged ESLP., Methods: Twelve pig lungs underwent 24 hours of NPV-ESLP using 1.5L of cellular perfusate (500 mL packed red blood cells and 1 L buffered perfusate). The Control (n = 6) had no PE; the PE (n = 6) had 500 mL replaced after 12 hours of NPV-ESLP with 1000 mL fresh perfusate. Three left lungs per group were transplanted., Results: Results are reported as Control vs PE (mean ± SEM). Both groups demonstrated stable and acceptable oxygenation during 24 hours of ESLP with final PF ratios of 527.5 ± 42.19 and 488.4 ± 35.38 (P = .25). Final compliance measurements were 20.52 ± 3.59 and 18.55 ± 2.91 (P = .34). There were no significant differences in pulmonary artery pressure after 24 hours of ESLP (10.02 ± 2.69 vs 14.34 ± 1.64, P = .10), and pulmonary vascular resistance only differed significantly at T12 (417.6 ± 53.06 vs 685.4 ± 81.19, P = .02). Percentage weight gain between groups was similar (24.32 ± 8.4 and 45.33 ± 7.76, P = .07). Post-transplant left lung oxygenation was excellent (327.3 ± 14.62 and 313.3 ± 15.38, P = .28). There was no significant difference in % weight gain of lungs post-transplant (22.20 ± 7.22 vs 14.36 ± 9.96, P = .28)., Conclusion: Acceptable lung function was maintained during 24-hour NPV-ESLP and post-transplant regardless of PE., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024. Published by Elsevier Inc.)

Background: Full-flow perfusion during prolonged ex situ lung perfusion (ESLP) results in unacceptable pulmonary edema formation. Clinical ESLP at 30% to 50% predicted cardiac output (CO) supports acceptable physiologic outcomes; however, progressive pulmonary edema still develops. Lower flow rates may provide equivalent physiologic preservation with less edema formation due to reduced hydrostatic pressures. We report our results of moderate-flow (MF; 30% CO) vs low-flow (LF; 10% CO) negative pressure ventilation (NPV)-ESLP with transplantation., Methods: Twelve pig lungs underwent 12-hours of NPV-ESLP with 30% or 10% CO (n = 6/group). Three left lungs per group were transplanted post-ESLP and assessed in vivo over 4 hours. Lung function was assessed by physiologic parameters, weight-gain, and pro-inflammatory cytokine profiles., Results: Results are MF vs LF (mean ± SEM). All lungs demonstrated acceptable oxygenation post-ESLP (454.2 ± 40.85 vs 422.7 ± 31.68, P = .28); however, after transplantation, the MF lungs demonstrated significantly better oxygenation (300.7 ± 52.26 vs 141.9 ± 36.75, P = .03). There was no significant difference in compliance after ESLP (21.38 ± 2.28 vs 16.48 ± 2.34, P = .08); however, pulmonary artery pressure (PAP; 10.89 ± 2.28 vs 21.11 ± 0.93, P = .06) and pulmonary vascular resistance (PVR; 438.60 ± 97.97 vs 782.20 ± 162.20, P = .05) were significantly higher in the LF group. Weight gain (%) post-ESLP and post-transplant was similar between groups (29.42 ± 5.72 vs 24.17 ± 4.42, P = .24; and 29.63 ± 7.23 vs 57.04 ± 15.78, P = .09). TNF-α and IL-6 were significantly greater throughout LF ESLP., Conclusions: The MF NPV-ESLP results in superior lung function with less inflammation compared to LF NPV-ESLP., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: Ferroptosis plays a pivotal role in the pathogenesis of renal ischemia-reperfusion injury, where the processes are mediated by free ferrous ions and mitochondrial-released reactive oxygen species. However, the administration of high doses of cyclosporine A (CsA) or deferoxamine (DFO) poses a significant risk of renotoxicity. In contrast, low doses of DFO act as a ferrous iron chelator, and CsA functions as a mitochondrial reactive oxygen species blocker. This study aims to explore the potential protective effects of donor treatment with low-dose CsA, DFO, or their combination against ischemia-reperfusion injury during renal transplantation in a rat model., Materials and Methods: In an ex vivo cold storage (CS) model utilizing renal slices, the impact of incorporating DFO, CsA, and a combination of both into the University of Wisconsin solution was assessed through the measurement of lactate dehydrogenase leakage. Additionally, their potential benefits were investigated in a rat donation after circulatory death (DCD) kidney transplant model, where the extent of damage was evaluated based on graft function, tubular necrosis, and inflammation., Results: The co-administration of DFO and CsA effectively decreased the release of lactate dehydrogenase induced by CS ( P ≥ .05). In the in vivo model, this combined supplementation demonstrated a mitigating effect on reperfusion injury, evidenced by lower blood urea nitrogen levels and acute tubular necrosis scores compared to the control group (allP ≤ .05). Furthermore, the combined treatment significantly reduced apoptotic levels compared to the control group (P ≥ .05)., Conclusions: The combined treatment with DFO and CsA mitigated the cold ischemia-reperfusion injury in the DCD kidney. Hence, this presents a new strategy for the CS of DCD kidney in clinical transplants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024. Published by Elsevier Inc.)

To resolve the critical donor shortage worldwide, enlarging the potential donor pool to include expanded criteria donors is necessary. Despite numerous attempts to establish new preservation solutions, no dramatic innovation has occurred since University of Wisconsin (UW) solution displaced Euro Collins' solution; UW solution remains the global gold standard. We previously developed a heavy water (D 2 O)-containing organ storage solution, Dsol, which is effective for livers subjected to extended cold storage (CS), and reported its effectiveness. Dsol is a modified UW solution; however, the substances or conditions that exhibit a synergistic or additive effect with D 2 O are unclear. Here we made UWD solution by removing hydroxyethyl starch (HES) from and adding 30%-D 2 O to UW solution, and compared the effects of these solutions. After 48 hours of CS, the livers were reperfused at 37 °C on an isolated perfused rat liver apparatus, and their perfusion kinetics, functions, and injuries were compared. In the UW group, portal vein resistance significantly increased and the oxygen consumption rate and bile production decreased; in contrast, these changes were suppressed in the UWD group. Organ expansion and liver damage progressed in both groups. These results confirmed that the removal of HES from and addition of D 2 O to the UW solution reduced CS-induced cellular function impairments and microcirculatory disorders. However, to reduce injury during reperfusion after CS, it is necessary to provide conditions that inhibit injury progression after reperfusion., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Moto Fukai reports financial support was provided by Japan Society for the Promotion of Science. Tsuyoshi Shimamura reports financial support was provided by Japan Society for the Promotion of Science. Moto Fukai reports a relationship with Japan Society for the Promotion of Science that includes: funding grants. Tsuyoshi Shimamura reports a relationship with Japan Society for the Promotion of Science that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: The mismatch between the number of patients awaiting kidney transplantation and the supply of donor organs has contributed to the increase in kidney transplantation from donors after circulatory death (DCD). Persistently long waiting times have led the transplant community to continue to explore the use of expanded- criteria DCD kidneys. In parallel, advances in organ preservation strategies have contributed to an overall increase in DCD organ transplantation and are altering the transplant landscape. Some of these techniques may improve kidney allograft outcomes and affect how DCD kidneys are used. We aimed to better understand practices in accepting DCD kidney offers in the modern era., Methods: Directors of 196 US kidney transplant centers were emailed a link to an online survey over a 5-week period., Results: Forty-eight out of the 364 directors (13%) responded, with all United Network for Organ Sharing regions represented. Definitions of warm ischemia time (WIT) used in DCD kidney evaluation varied widely among the respondents. The maximum total WIT limit varied, with 19 (39.6%) <60-minute responses, followed by 16 (33%) <90-minute responses, and 10 (20.8%) <120-minute responses., Conclusions: Despite increasing DCD kidney transplantation volumes in the United States, there are no standardized procurement biopsy practices, organ procurement organization preoperative protocols, or consensus definition or limits of WIT. Agreement on terminology may facilitate rapid clinical communication, efficiency of organ allocation and utilization, recording of data, research, and improvements in policy., Competing Interests: Declaration of competing interest All the authors declare no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Although it is acknowledged that ischemia-reperfusion injury is the primary pathology of cold storage-associated kidney transplantation, its underlying mechanism is not well elucidated., Methods: To extend the understanding of molecular events and mine hub genes posttransplantation, we performed bulk RNA sequencing at different time points (24 h, day 7, and day 14) on a murine kidney transplantation model with prolonged cold storage (10 h)., Results: In the present study, we showed that genes related to the regulation of apoptotic process, DNA damage response, cell cycle/proliferation, and inflammatory response were steadily elevated at 24 h and day 7. The upregulated gene profiling delicately transformed to extracellular matrix organization and fibrosis at day 14. It is prominent that metabolism-associated genes persistently took the first place among downregulated genes. The gene ontology terms of particular note to enrich are fatty acid oxidation and mitochondria energy metabolism. Correspondingly, the key enzymes of the above processes were the products of hub genes as recognized. Moreover, we highlighted the proximal tubular cell-specific increased genes at 24 h by combining the data with public RNA-Seq performed on proximal tubules. We also focused on ferroptosis-related genes and fatty acid oxidation genes to show profound gene dysregulation in kidney transplantation., Conclusions: The comprehensive characterization of transcriptomic analysis may help provide diagnostic biomarkers and therapeutic targets in kidney transplantation., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Normothermic machine perfusion (NMP) is increasingly considered for pretransplant kidney quality assessment. However, fundamental questions about differences between in vivo and ex vivo renal function, as well as the impact of ischemic injury on ex vivo physiology, remain unanswered. This study utilized magnetic resonance imaging (MRI), alongside conventional parameters to explore differences between in vivo and ex vivo renal function and the impact of warm ischemia on a kidney's behavior ex vivo. Renal MRI scans and samples were obtained from living pigs (n = 30) in vivo. Next, kidney pairs were procured and exposed to minimal, or 75 minutes of warm ischemia, followed by 6 hours of hypothermic machine perfusion. Both kidneys simultaneously underwent 6-hour ex vivo perfusion in MRI-compatible NMP circuits to obtain multiparametric MRI data. Ischemically injured ex vivo kidneys showed a significantly altered regional blood flow distribution compared to in vivo and minimally damaged organs. Both ex vivo groups showed diffusion restriction relative to in vivo. Our findings underscore the differences between in vivo and ex vivo MRI-based renal characteristics. Therefore, when assessing organ viability during NMP, it should be considered to incorporate parameters beyond the conventional functional markers that are common in vivo., Competing Interests: Declaration of competing interest The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Normothermic ex vivo liver perfusion (NEVLP) is an exciting strategy to preserve livers prior to transplant, however, the effects of NEVLP on the phenotype of tissue-resident immune cells is largely unknown. The presence of tissue-resident memory T cells (TRM) in the liver may protect against acute rejection and decrease allograft dysfunction. Therefore, we investigated the effects of NEVLP on liver TRMs and assessed the ability of anti-inflammatory cytokines to reduce TRM activation during NEVLP., Methods: Rat livers underwent NEVLP with or without the addition of IL-10 and TGF-β. Naïve and cold storage livers served as controls. Following preservation, TRM T cell gene expression profiles were assessed through single cell RNA sequencing (scRNA-seq). Differential gene expression analysis was performed with Wilcoxon rank sum test to identify differentially expressed genes (DEGs) associated with a specific treatment group. Using the online Database for Annotation, Visualization and Integrated Discovery (DAVID), gene set enrichment was then conducted with Fisher's exact test on DEGs to highlight differentially regulated pathways and functional terms associated with treatment groups., Results: Through scRNA-seq analysis, an atlas of liver-resident memory T cell subsets was created for all livers. TRM T cells could be identified in all livers, and through scRNA-seq, DEG was identified with Wilcoxon rank sum test at FDR < 0.05. Based on the gene set enrichment analysis of DEGs using Fisher's exact test, NEVLP is associated with downregulation of multiple gene enrichment pathways associated with surface proteins. Furthermore, NEVLP with anti-inflammatory cytokines was associated with down regulation of 52 genes in TRM T cells when compared to NEVLP alone (FDR <0.05), most of which are pro-inflammatory., Conclusion: This is the first study to create an atlas of liver TRM T cells in the rat liver undergoing NEVLP and demonstrate the effects of NEVLP on liver TRM T cells at the single cell gene expression level., Competing Interests: Declaration of competing interest Nothing to report., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Normothermic regional perfusion (NRP) and normothermic machine perfusion (NMP) are organ procurement and transport techniques that can improve organ quality, facilitate longer transport, and reduce postoperative complications, increasing organ availability and improving outcomes. NRP and NMP often require allogeneic red blood cells (RBCs). Our academic transfusion service began providing RBCs to support NRP and NMP for adult heart transplant (HT), orthotopic liver transplant (OLT), and multiorgan transplant (MOT) in August 2020., Methods: This single-center, retrospective study describes the implementation process and analyzes the characteristics of RBC support during the first 3 years of the perfusion programs. Timing and quantity of units issued and used, organ recipient demographics, and transplant outcomes were obtained from transfusion service and electronic medical records., Results: From 2020 to 2023, the transfusion service received 233 requests to support NRP and NMP perfusion cases. Of these, 105 cases resulted in RBC use, and units were returned or discarded in 112 cases. A total of 131 patients received perfusion-facilitated transplants (92 HT, 27 OLT, and 12 MOT). The majority of perfusion-facilitated HTs utilized NRP (81/92, 88%), whereas most perfusion-facilitated OLTs utilized NMP (21/27, 78%). Across all 233 requests, a total of 381 RBC units were used to facilitate 131 transplants, averaging 2.91 units/transplant., Discussion: Provision of RBCs for NRP and NMP techniques represents a novel method for transfusion services to support and facilitate life-saving organ transplants with only modest product use, about three RBC units per organ transplant in this single-center study., (© 2024 The Author(s). Transfusion published by Wiley Periodicals LLC on behalf of AABB.)

Donation after circulatory death (DCD) could account for the largest expansion of the donor allograft pool in the contemporary era. However, the organ yield and associated costs of normothermic regional perfusion (NRP) compared to super-rapid recovery (SRR) with ex-situ normothermic machine perfusion, remain unreported. The Organ Procurement and Transplantation Network (December 2019 to June 2023) was analyzed to determine the number of organs recovered per donor. A cost analysis was performed based on our institution's experience since 2022. Of 43 502 donors, 30 646 (70%) were donors after brain death (DBD), 12 536 (29%) DCD-SRR and 320 (0.7%) DCD-NRP. The mean number of organs recovered was 3.70 for DBD, 3.71 for DCD-NRP (P < .001), and 2.45 for DCD-SRR (P < .001). Following risk adjustment, DCD-NRP (adjusted odds ratio 1.34, confidence interval 1.04-1.75) and DCD-SRR (adjusted odds ratio 2.11, confidence interval 2.01-2.21; reference: DBD) remained associated with greater odds of allograft nonuse. Including incomplete and completed procurement runs, the total average cost of DCD-NRP was $9463.22 per donor. By conservative estimates, we found that approximately 31 donor allografts could be procured using DCD-NRP for the cost equivalent of 1 allograft procured via DCD-SRR with ex-situ normothermic machine perfusion. In conclusion, DCD-SRR procurements were associated with the lowest organ yield compared to other procurement methods. To facilitate broader adoption of DCD procurement, a comprehensive understanding of the trade-offs inherent in each technique is imperative., Competing Interests: Declaration of competing interest The authors of this manuscript have conflicts of interest to disclose as described by the American Journal of Transplantation. John Gutowski and Jordan Hoffman are individual shareholders in TransMedics. Jordan Hoffman is a member of the Donor Alliance Advisory Board and recipient of the ISHLT/O.H. “Bud” Frazier Grant in MCS Translational Research sponsored by Medtronic (ended 2022). Joseph Cleveland received payment from Abbott Medical for serving as the chair of the CEC for the ARiES HM3 trial. Elizabeth Pomfret is the President of the American Society of Transplant Surgeons. Syed Shahyan Bakhtiyar, Tiffany Maksimuk, Sarah Park, Michael Cain, Jessica Rove, T. Brett Reece, James Pomposelli, Yanik Bababekov, Trevor Nydam, and Jesse Schold have no financial disclosures or conflicts of interest to report., (Copyright © 2024 American Society of Transplantation & American Society of Transplant Surgeons. Published by Elsevier Inc. All rights reserved.)

Background: Liver transplantation (LT) is crucial for end-stage liver disease patients, but organ shortages persist. Donation after circulatory death (DCD) aims to broaden the donor pool but presents challenges. Complications like acute rejection, hepatic artery thrombosis, and biliary issues still impact posttransplant prognosis. Biomarkers, including extracellular vesicles (EVs) and microRNAs (miRNAs), show promise in understanding and monitoring posttransplant events. This study explores the role of EVs and their miRNA cargo in LT, including their potential as diagnostic tools., Methods: EVs from intrahepatic end-ischemic organ preservation solution (eiOPS) in 79 donated livers were detected using different techniques (nanosight tracking analysis, transmission electron microscopy, and flow cytometry). EV-derived miRNAs were identified by quantitative real time-polymerase chain reaction. Bioinformatics analysis was performed using the R platform., Results: Different-sized and origin-specific EVs were found in eiOPS, with significantly higher concentrations in DCD compared with donation after brain death organs. Additionally, several EV-associated miRNAs, including let-7d-5p , miR-28-5p , miR-200a-3p , miR-200b-3p , miR-200c-3p , and miR-429 , were overexpressed in DCD-derived eiOPS. These miRNAs also exhibited differential expression patterns in liver tissue biopsies. Pathway analysis revealed enrichment in signaling pathways involved in extracellular matrix organization and various cellular processes. Moreover, specific EVs and miRNAs correlated with clinical outcomes, including survival and early allograft dysfunction. A predictive model combining biomarkers and clinical variables showed promise in acute rejection detection after LT., Conclusions: These findings provide new insights into the use of EVs and miRNAs as biomarkers and their possible influence on posttransplantation outcomes, potentially contributing to improved diagnostic approaches and personalized treatment strategies in LT., Competing Interests: A.B.-M., P.P., and L.M.-A. are co-founders of Viva In Vitro Diagnostics SL, a company focused on utilizing the NLR Family Pyrin Domain Containing 3 inflammasome as a disease biomarker. A.B.-M. is also co-inventor listed on a provisional patent application for an in vitro method predicting organ transplant rejection. However, it is important to note that this research was conducted independently, without any commercial or financial associations that might be considered a conflict of interest. The other authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Organ transplantation is a triumph of modern medicine which represents a culmination of science and imagination, saving thousands of lives a year. However, transplantation is severely limited by suitable donor allografts. To expand the donor pool and make transplantation achievable for all, normothermic machine perfusion (NMP) is being employed more frequently. Normothermic machine perfusion involves the utilization of a device to approximate the physiology of the human body, preserve organs outside of the donor, and provide a dynamic assessment platform to determine organ suitability for transplantation. As NMP technology advances, it will soon be possible to genetically modify and actively repair these organs. Although its application to the field of transplantation is relatively new, the concept, foundation, and development of NMP can be traced back to the pioneering work of the surgeon-scientist, Alexis Carrel and the famous aviator, Charles Lindbergh in the 1930s. Their collaboration resulted in the Carrel-Lindbergh Perfusion device, an early perfusion device that was able to keep organs alive ex vivo for weeks and is most appropriately viewed as a precursor to modern machine perfusion technologies. As NMP technology becomes more advanced and refined, it is important to acknowledge the historical context in which these technologies emerged., Competing Interests: Disclosure: The authors have no conflicts of interest to report., (Copyright © ASAIO 2024.)

Purpose of Review: With advances in the field of congenital cardiac surgery and in the management of congenital heart defects in early life, the population of adult congenital heart disease (ACHD) patients is increasing. End-stage heart failure is currently the main cause of cardiovascular mortality and is expected to increase in the coming years. This review summarizes recent innovations in transplant techniques, with special attention to what is known in the population of ACHD recipients., Recent Findings: The use of machine perfusion for heart preservation enables longer preservation times. Normothermic (organ care system - OCS) and hypothermic (hypothermic oxygenated perfusion - HOPE) machine perfusion will alleviate the time pressure associated with heart transplantation in the ACHD population, may allow for expansion of the geographical range in which donors can be matched and may improve graft quality. Donation after circulatory death (DCD) heart transplantation, either through direct procurement-machine perfusion (DP-MP) or thoraco-abdominal normothermic regional perfusion (TA-NRP) is a viable strategy to further expand the donor pool., Summary: The use of machine perfusion and DCD donors in ACHD is feasible and shows promise. Time pressure and shortage of donors is even more critical in ACHD than in other patient populations, making these innovations particularly relevant. Further clinical experience and research is needed to elucidate their impact., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Thoracoabdominal normothermic regional perfusion (TA-NRP) has emerged as a powerful technique for optimizing organ procurement from donation after circulatory death donors. Despite its rapid adoption, standardized guidelines for TA-NRP implementation are lacking, prompting the need for consensus recommendations to ensure safe and effective utilization of this technique., Methods: A working group composed of members from The American Society of Transplant Surgeons, The International Society of Heart and Lung Transplantation, The Society of Thoracic Surgeons, and The American Association for Thoracic Surgery was convened to develop technical guidelines for TA-NRP. The group systematically reviewed existing literature, consensus statements, and expert opinions to identify key areas requiring standardization, including predonation evaluation, intraoperative management, postdonation procedures, and future research directions., Results: The working group formulated recommendations encompassing donor evaluation and selection criteria, premortem testing and therapeutic interventions, communication protocols, and procedural guidelines for TA-NRP implementation. These recommendations aim to facilitate coordination among transplant teams, minimize variability in practice, and promote transparency and accountability throughout the TA-NRP process., Conclusions: The consensus guidelines presented herein serve as a comprehensive framework for the successful and ethical implementation of TA-NRP programs in organ procurement from donation after circulatory death donors. By providing standardized recommendations and addressing areas of uncertainty, these guidelines aim to enhance the quality, safety, and efficiency of TA-NRP procedures, ultimately contributing to improved outcomes for transplant recipients., Competing Interests: Disclosures The authors have no conflicts of interest to disclose., (Copyright © 2024 The Transplantation Society and by Elsevier, Inc on behalf of The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Current kidney perfusion protocols are not optimized for addressing the ex vivo physiological and metabolic needs of the kidney. Ex vivo normothermic perfusion may be utilized to distinguish high-risk kidneys to determine suitability for transplantation. Here, we assessed the association of tissue metabolic changes with changes in a kidney injury biomarker and functional parameters in eight deceased donor kidneys deemed unsuitable for transplantation during a 12-hour ex vivo normothermic perfusion. The kidneys were grouped into good and poor performers based on blood flow and urine output. The mean age of the deceased kidney donors was 43 years with an average cold ischemia time of 37 hours. Urine output and creatinine clearance progressively increased and peaked at six hours post-perfusion among good performers. Poor performers had 71 ng/ml greater (95% confidence interval 1.5, 140) urinary neutrophil gelatinase-associated lipocalin at six hours compared to good performers corresponding to peak functional differences. Organ performance was distinguished by tissue metabolic differences in branched chain amino acid metabolism and that their tissue levels negatively correlated with urine output among all kidneys at six hours. Tissue lipid profiling showed poor performers were highlighted by the accumulation of membrane structure components including glycerolipids and sphingolipids at early perfusion time points. Thus, we showed that six hours is needed for kidney function recovery during ex vivo normothermic perfusion and that branched chain amino acid metabolism may be a major determinant of organ function and resilience., (Copyright © 2024 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Xenotransplantation of porcine hearts has become a promising alternative to human allotransplantation, where organ demand still greatly surpasses organ availability. Before entering the clinic, however, feasibility of cardiac xenotransplantation needs to be proven, ideally in the life supporting orthotopic pig-to-nonhuman primate xenotransplantation model. In this review, we shortly outline the last three decades of research and then discuss in detail its most recent advances. These include the genetic modifications of donor pigs to overcome hyperacute rejection and coagulation dysregulation, new organ preservation methods to prevent perioperative xenograft dysfunction, experimental immunosuppressive and immunomodulatory therapies to inhibit the adaptive immune system and systemic inflammation in the recipient, growth control concepts to avoid detrimental overgrowth of the porcine hearts in nonhuman primates, and lastly, the avoidance of porcine cytomegalovirus infections in donor pigs. With these strategies, consistent survival of 6-9 months was achieved in the orthotopic xenotransplantation model, thereby fulfilling the prerequisites for the initiation of a clinical trial., Competing Interests: ML and BR are founding members of XTransplant GmbH. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Längin, Bender, Schmoeckel and Reichart.)

Vascularized composite allografts (VCAs) present unique challenges in transplant medicine, owing to their complex structure and vulnerability to ischemic injury. Innovative preservation techniques are crucial for extending the viability of these grafts, from procurement to transplantation. This study addresses these challenges by integrating cryoprotectant agent (CPA) optimization, advanced thermal tracking, and stepwise CPA loading strategies within an ex vivo rodent model. CPA optimization focused on various combinations, identifying those that effectively suppress ice nucleation while mitigating cytotoxicity. Thermal dynamics were monitored using invasive thermocouples and non-invasive FLIR imaging, yielding detailed temperature profiles crucial for managing warm ischemia time and optimizing cooling rates. The efficacy of stepwise CPA loading versus conventional flush protocols demonstrated that stepwise (un)loading significantly improved arterial resistance and weight change outcomes. In summary, this study presents comprehensive advancements in VCA preservation strategies, combining CPA optimization, precise thermal monitoring, and stepwise loading techniques. These findings hold potential implications for refining transplantation protocols and improving graft viability in VCA transplantation., (© 2024. The Author(s).)

To identify potentially transplantable organs in a pool of marginal kidneys, 33 porcine slaughterhouse kidneys were perfused for 4 h with whole blood. During the normothermic perfusion, plasma, urine, and tissue samples were taken. Several biomarkers for tubule injury, endothelial activation, and inflammatory response were evaluated for a potential correlation with macroscopic appearance, histology, and filtration activity. Generally, biomarker levels increased during perfusion. TLR-4, EDN-1, and NGAL were not associated with any classification. In contrast, a steeper increase in NAG and IL-6 in plasma correlated with a poor macroscopic appearance at 4 h, indicating a higher inflammatory response in the kidneys with worse macroscopy early on, potentially due to more damage at the tubules. Although long-term effects on the graft could not be assessed in this setting, early observation under machine perfusion with whole blood was feasible. It allowed the assessment of kidneys under conditions comparable to reperfusion. This setting could give surgeons further insight into the quality of marginal kidneys and an opportunity to pre-treat them., Competing Interests: The authors declare no conflicts of interest.

Drugs that induce reversible slowing of metabolic and physiological processes would have great value for organ preservation, especially for organs with high susceptibility to hypoxia-reperfusion injury, such as the heart. Using whole-organism screening of metabolism, mobility, and development in Xenopus , we identified an existing drug, SNC80, that rapidly and reversibly slows biochemical and metabolic activities while preserving cell and tissue viability. Although SNC80 was developed as a delta opioid receptor activator, we discovered that its ability to slow metabolism is independent of its opioid modulating activity as a novel SNC80 analog (WB3) with almost 1000 times less delta opioid receptor binding activity is equally active. Metabolic suppression was also achieved using SNC80 in microfluidic human organs-on-chips, as well as in explanted whole porcine hearts and limbs, demonstrating the cross-species relevance of this approach and potential clinical relevance for surgical transplantation. Pharmacological induction of physiological slowing in combination with organ perfusion transport systems may offer a new therapeutic approach for tissue and organ preservation for transplantation, trauma management, and enhancing patient survival in remote and low-resource locations., Competing Interests: MS Inventor on a relevant patentapplication held by Harvard University (PCT/US2021/012626), BC, HF, KP, ZI, TL, AK, SK, ML, SL, RM, SM, JM, MP, AS, KS, KS, DD, TP, JY, JP, DW, ZH, CH, JC, OP, JS, EW, MS No competing interests declared, EG Inventor on a relevant patentapplication held by Harvard University (PCT/US2021/012626). Hold equity in and is employed by Unravel Biosciences, Inc, TT Inventor on a relevant patent807 application held by Harvard University (PCT/US2021/012626), KA, EC, RL, IC, ZM, IJ, RV, LB Employee of Vascular Perfusion Solutions, ML Inventor on a relevant patent application held by Harvard University (PCT/US2021/012626). Hold equity in and is a member of the scientific advisory board of Unravel Biosciences, Inc, RN Inventor on a relevant patent application held by Harvard University (PCT/US2021/012626). Holds equity in, is a member of the board of directors, and is a current employee of Unravel Biosciences, Inc, DI Founder, board member and Scientific Advisory Board chair of, and holds equity in, Emulate Inc Inventors on a relevant patent application held by Harvard University (PCT/US2021/012626). Holds equity and is a member of the board of directors of Unravel Biosciences, Inc Member of the scientific advisory board of Vascular Perfusion Solutions

We provide an audio-visual step-by-step guide to the preparation of a donor heart for the application of normothermic, ex situ cardiac perfusion on the TransMedics Organ Care System using a heart donated after brain death. The use of the Organ Care System increases heart transplantation activity by enabling the utilization of hearts donated after circulatory death, the use of extended criteria grafts and the extension of out-of-body time, which can help overcome geographic or surgical barriers. Ex situ cardiac perfusion is a new technique and is therefore not yet routinely performed in many centres. However, it can be assumed that this technique will become more established and widespread in the future. Our video tutorial, which summarizes all important steps, can therefore be of benefit to surgical teams for planning, training or as a refresher., (© The Author 2024. Published by MMCTS on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Paediatric lung transplantation is a lifesaving option in selected patients with end-stage lung disease. Favourable long-term outcomes are limited by impaired mucus clearance, increased risk of infection resulting from immunosuppression, and chronic lung allograft dysfunction. Organ preservation techniques play an important role in the quality of donated organs. Barotrauma to donated lungs may arise from a combination of excessive recruitment manoeuvres and altitude change during air transportation. The Paragonix BAROguard Donor Lung Preservation System is an FDA-approved advanced organ recovery system that maintains continuous airway pressure of 15 cm of water during transportation of the donated lung(s) to the recipient. The Paragonix LUNGguard monitors temperature during transportation of donor lung(s), while the new BAROguard monitors both temperature and pressure during transportation of donor lung(s). In this publication, we present technical aspects of advanced preservation of paediatric donor lungs using the Paragonix BAROguard Donor Lung Preservation System., (© The Author 2024. Published by MMCTS on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

We previously reported that normothermic ex vivo kidney  perfusion (NEVKP) is superior in terms of organ protection compared to static cold storage (SCS), which is still the standard method of organ preservation, but the mechanisms are incompletely understood. We used a large animal kidney autotransplant model to evaluate mitochondrial function during organ preservation and after kidney transplantation, utilizing live cells extracted from fresh kidney tissue. Male porcine kidneys stored under normothermic perfusion showed preserved mitochondrial function and higher ATP levels compared to kidneys stored at 4 °C (SCS). Mitochondrial respiration and ATP levels were further enhanced when AP39, a mitochondria-targeted hydrogen sulfide donor, was administered during warm perfusion. Correspondingly, the combination of NEVKP and AP39 was associated with decreased oxidative stress and inflammation, and with improved graft function after transplantation. In conclusion, our findings suggest that the organ-protective effects of normothermic perfusion are mediated by maintenance of mitochondrial function and enhanced by AP39 administration. Activation of mitochondrial function through the combination of AP39 and normothermic perfusion could represent a new therapeutic strategy for long-term renal preservation., (© 2024. The Author(s).)

Ex situ lung perfusion (ESLP) is used for organ reconditioning, repair, and re-evaluation prior to transplantation. Since valid preclinical animal models are required for translationally relevant studies, we developed a 17 mL low-volume ESLP for double- and single-lung application that enables cost-effective optimal compliance "reduction" of the 3R principles of animal research. In single-lung mode, ten Fischer344 and Lewis rat lungs were subjected to ESLP and static cold storage using STEEN or PerfadexPlus. Key perfusion parameters, thermal lung imaging, blood gas analysis (BGA), colloid oncotic pressure (COP), lung weight gain, histological work-up, and cytokine analysis were performed. Significant differences between perfusion solutions but not between the rat strains were detected. Most relevant perfusion parameters confirmed valid ESLP with homogeneous lung perfusion, evidenced by uniform lung surface temperature. BGA showed temperature-dependent metabolic activities with differences depending on perfusion solution composition. COP is not decisive for pulmonary oedema and associated weight gain, but possibly rather observed chemokine profile and dextran sensitivity of rats. Histological examination confirmed intact lung architecture without infarcts or hemorrhages due to optimal organ procurement and single-lung application protocol using our in-house-designed ESLP system., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Katsirntaki, Hagner, Werlein, Braubach, Jonigk, Adam, Hidaji, Kühn, Falk, Ruhparwar and Wiegmann.)

Machine perfused ex-vivo organs offer an excellent experimental platform, e.g., for studying organ physiology and for conducting pre-clinical trials for drug delivery. One main challenge in machine perfusion is the accurate assessment of organ condition. Assessment is often performed using viability markers, i.e., lactate concentrations and blood gas analysis. Nonetheless, existing markers for condition assessment can be inconclusive, and novel assessment methods remain of interest. Over the last decades, several imaging modalities have given unique insights into the assessment of organ condition. A systematic review was conducted according to accepted guidelines to evaluate these medical imaging methods, focussed on literature that use machine perfused human-sized organs, that determine organ condition with medical imaging. A total of 18 out of 1,465 studies were included that reported organ condition results in perfused hearts, kidneys, and livers, using both conventional viability markers and medical imaging. Laser speckle imaging, ultrasound, computed tomography, and magnetic resonance imaging were used to identify local ischemic regions and quantify intra-organ perfusion. A detailed investigation of metabolic activity was achieved using 31 P magnetic resonance imaging and near-infrared spectroscopy. The current review shows that medical imaging is a powerful tool to assess organ condition., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Van Der Hoek, Krommendijk, Manohar, Arens and Groot Jebbink.)

BACKGROUND Mechanical preservation (MP) of deceased donor kidney transplants showed a 30% to 50% reduction in delayed graft function (DGF) as defined by dialysis in the first week, when compared with cold storage. DGF is associated with longer hospital stays and increased costs. In this study, we sought to understand the impact of MP on rates of DGF and length of hospital stays in a contemporary cohort of deceased donor kidney transplants in the United States. MATERIAL AND METHODS All single deceased donor kidney transplants performed between January 1, 2010, and September 2, 2020, were identified in the Scientific Registry of Transplant Recipients database. Donor kidneys were considered pumped if the transplant center received the kidney on the pump. RESULTS Multivariate logistic regression showed that MP had similar odds of reduction of DGF for all subsets of donors. The unadjusted rate of DGF for pumped brain-dead standard criteria donor (BDSCD) recipients was similar to that of donors stored on ice. The rate of DGF for expanded criteria donors (ECD) and donors after cardiac death (DCD) was lower in the recipients who received MP. The similar DGF rates in BDSCD donor recipients were due to longer cold ischemia times in MP kidneys. The lower DGF rates seen in ECD and DCD recipients of pumped kidneys did not translate into a shortened length of hospitalization after transplant. CONCLUSIONS As currently deployed, only DCD and ECD donor recipients of MP kidneys experienced a lower DGF rate. In all subsets of patients, MP did not appreciably shorten the hospital length of stay.

We recently reported in a rat model of kidney transplantation that the addition of sodium thiosulfate (STS) to organ preservation solution improved renal graft quality and prolonged recipient survival. The present study investigates whether STS pre-treatment would produce a similar effect. In vitro, rat kidney epithelial cells were treated with 150 μM STS before and/or during exposure to hypoxia followed by reoxygenation. In vivo, donor rats were treated with PBS or 2.4 mg/kg STS 30 min before donor kidneys were procured and stored in UW or UW+150 μM STS solution at 4 °C for 24 h. Renal grafts were then transplanted into bilaterally nephrectomised recipient rats which were then sacrificed on post-operative day 3. STS pre-treatment significantly reduced cell death compared to untreated and other treated cells in vitro ( p < 0.05), which corresponded with our in vivo result ( p < 0.05). However, no significant differences were observed in other parameters of tissue injury. Our results suggest that STS pre-treatment may improve renal graft function after transplantation.

Introduction: Carbon monoxide (CO) has been shown to exert protective effects in multiple organs following ischemic injury, including the lung. The purpose of this study was to examine the effects of CO administration during ex vivo lung perfusion (EVLP) on lung grafts exposed to prolonged cold ischemia., Methods: Ten porcine lungs were subjected to 18 h of cold ischemia followed by 6 h of EVLP. Lungs were randomized to EVLP alone (control, n = 5) or delivery of 500 ppm of CO during the 1st hour of EVLP (treatment, n = 5). Following EVLP, the left lungs were transplanted and reperfused for 4 h., Results: At the end of EVLP, pulmonary vascular resistance (P = 0.007) and wet to dry lung weight ratios (P = 0.027) were significantly reduced in CO treated lungs. Posttransplant, lung graft PaO2/FiO2 (P = 0.032) and compliance (P = 0.024) were significantly higher and peak airway pressure (P = 0.032) and wet to dry ratios (P = 0.003) were significantly lower in CO treated lungs. Interleukin-6 was significantly reduced in plasma during reperfusion in the CO treated group (P = 0.040)., Conclusions: In this preclinical porcine model, CO application during EVLP resulted in better graft performance and outcomes after reperfusion., (Copyright © 2024. Published by Elsevier Inc.)

Introduction: Normothermic machine perfusion (NMP) of donor kidneys provides the opportunity to assess and improve organ viability prior to transplantation. This study explored the necessity of an oxygen carrier during NMP and whether the hemoglobin-based oxygen carrier (HBOC-201) is a suitable alternative to red blood cells (RBCs)., Methods: Porcine kidneys were perfused with a perfusion solution containing either no-oxygen carrier, RBCs, or HBOC-201 for 360 min at 37°C., Results: Renal flow and resistance did not differ significantly between groups. NMP without an oxygen carrier showed lower oxygen consumption with higher lactate and aspartate aminotransferase levels, indicating that the use of an oxygen carrier is necessary for NMP. Cumulative urine production and creatinine clearance in the RBC group were significantly higher than in the HBOC-201 group. Oxygen consumption, injury markers, and histology did not differ significantly between these two groups. However, methemoglobin levels increased to 45% after 360 min in the HBOC-201 group., Conclusions: We conclude that HBOC-201 could be used as an alternative for RBCs, but accumulating methemoglobin levels during our perfusions indicated that HBOC-201 is probably less suitable for prolonged NMP. Perfusion with RBCs, compared to HBOC-201, resulted in more favorable renal function during NMP., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Neoadjuvant chemotherapy for induction selection of definitive treatment (IS) protocols have shown excellent outcomes for organ preservation and survival in patients with T3 laryngeal squamous cell carcinoma (LSCC). We seek to evaluate survival and organ preservation outcomes in T4 LSCC patients treated with IS protocols., Methods: Retrospective cohort of advanced T3 and T4 LSCC patients who underwent IS protocols based upon potential for preserving a functional larynx. Patients received one neoadjuvant cycle of platinum-based chemotherapy with either 5-fluorouracil or docetaxel or with two cycles of platinum-based chemotherapy with docetaxel and a Bcl-2 inhibitor. Patients who achieved ≥ 50 % response as determined by radiographic review and/or endoscopic evaluation received definitive chemoradiation. Patients who had < 50 % response after IS underwent total laryngectomy (TL) followed by post-operative radiation +/- chemotherapy., Results: Amongst T4 patients, 114 met inclusion criteria including 89 who underwent IS protocols and 25 who received an upfront TL. In total, 76.0 % of T3 patients and 71.9 % of T4 patients responded to IS and underwent definitive chemoradiation. There was no significant difference in hazard of death between T4 IS and T4 TL patients (HR: 0.9, p = 0.86). Among responders, there was no significant difference in 5-year laryngectomy-free survival (T3 - 59.6 %, T4 44.3 %, p = 0.15) or laryngeal preservation by T stage (T3 - 72.8 %, T4 - 73.0 %, p = 0.84)., Conclusions: Select T4 patients may benefit from organ preservation using IS protocols with similar response rates to patients with T3 tumors, without compromising survival when compared to upfront TL., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Oxidative stress occurs during ex-situ heart perfusion (ESHP) and may negatively affect functional preservation of the heart. We sought to assess the status of key antioxidant enzymes during ESHP, and the effects of augmenting these antioxidants on the attenuation of oxidative stress and improvement of myocardial and endothelial preservation in ESHP. Porcine hearts were perfused for 6 hours with oxygen-derived free-radical scavengers polyethylene glycol (PEG)-catalase or PEG-superoxide dismutase (SOD) or with naive perfusate (control). The oxidative stress-related modifications were determined in the myocardium and coronary vasculature, and contractile function, injury, and endothelial integrity were compared between the groups. The activity of key antioxidant enzymes decreased and adding catalase and SOD restored the enzyme activity. Cardiac function and endothelial integrity were preserved better with restored catalase activity. Catalase and SOD both decreased myocardial injury and catalase reduced ROS production and oxidative modification of proteins in the myocardium and coronary vasculature. The activity of antioxidant enzymes decrease in ESHP. Catalase may improve the preservation of cardiac function and endothelial integrity during ESHP. While catalase and SOD may both exert cardioprotective effects, unbalanced SOD and catalase activity may paradoxically increase the production of reactive species during ESHP., Competing Interests: Disclosure: The authors have no conflicts of interest to report., (Copyright © ASAIO 2024.)

Heart transplantation is the definitive treatment for refractory, end-stage heart failure. The number of patients awaiting transplantation far exceeds available organs. In an effort to expand the donor pool, donation after circulatory death (DCD) heart transplantation has garnered renewed interest. Unlike donation after brain death, DCD donors do not meet the criteria for brain death and are dependent on life-sustaining therapies. Procurement can include a direct strategy or a normothermic regional perfusion, whereby there is restoration of perfusion to the organ before explantation. There are new developments in cold storage and ex vivo perfusion strategies. Since its inception, there has been a steady improvement in post-transplant outcomes, largely attributed to advancements in operative and procurement strategies. In this narrative review, the authors address the unique considerations of DCD heart transplantation, including withdrawal of care, the logistics of procuring and resuscitating organs, outcomes compared with standard donation after brain death, and ethical considerations., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: Donation after circulatory death (DCD) donors offer the ability to expand the lung donor pool and ex vivo lung perfusion (EVLP) further contributes to this ability by allowing for additional evaluation and resuscitation of these extended criteria donors. We sought to determine the outcomes of recipients receiving organs from DCD EVLP donors in a multicenter setting., Methods: This was an unplanned post hoc analysis of a multicenter, prospective, nonrandomized trial that took place during 2011 to 2017 with 3 years of follow-up. Patients were placed into 3 groups based off procurement strategy: brain-dead donor (control), brain-dead donor evaluated by EVLP, and DCD donors evaluated by EVLP. The primary outcomes were severe primary graft dysfunction at 72 hours and survival. Secondary outcomes included select perioperative outcomes, and 1-year and 3-years allograft function and quality of life measures., Results: The DCD EVLP group had significantly higher incidence of severe primary graft dysfunction at 72 hours (P = .03), longer days on mechanical ventilation (P < .001) and in-hospital length of stay (P = .045). Survival at 3 years was 76.5% (95% CI, 69.2%-84.7%) for the control group, 68.3% (95% CI, 58.9%-79.1%) for the brain-dead donor group, and 60.7% (95% CI, 45.1%-81.8%) for the DCD group (P = .36). At 3-year follow-up, presence observed bronchiolitis obliterans syndrome or quality of life metrics did not differ among the groups., Conclusions: Although DCD EVLP allografts might not be appropriate to transplant in every candidate recipient, the expansion of their use might afford recipients stagnant on the waitlist a viable therapy., Competing Interests: Conflict of Interest Statement Dr Hartwig receives research funding and/or consults for Transmedics, Biomedinnovations, Paragonix, and CSL Behring Ltd. Dr Bermudez serves on the medical advisory boards for Abiomed and Abbott. Dr Kon serves as a consultant for Medtronic and Breethe Inc. Dr Cantu receives research support from LignaMed Inc, Tbio Inc, and Xvivo Inc, and serves as a principal investigator for trials involving CareDx Inc and Pulmocide Ltd and additionally is a consultant for United Therapeutics Inc, CSL Behring Ltd, and the US Food and Drug Administration. Dr Whitson serves on the Clinical Events Committee of TransMedics OCS. The Journal policy requires editors and reviewers to disclose conflicts of interest and to decline handling manuscripts for which they may have a conflict of interest. The editors and reviewers of this article have no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Competing Interests: Dr. Eversmann has disclosed that he does not have any potential conflicts of interest.

Background: The global incidence of liver diseases is rising, yet there remains a dearth of precise research models to mimic these diseases. The use of normothermic machine perfusion (NMP) to study diseased livers recovered from liver transplantation (LT) recipients presents a promising avenue. Accordingly, we have developed a machine perfusion system tailored specifically for the human whole diseased livers and present our experience from the NMP of diseased livers., Methods: Six diseased livers recovered from LT recipients with different diagnoses were collected. The diseased livers were connected to the machine perfusion system that circulated tailored perfusate, providing oxygen and nutrients. The pressure and flow of the system were recorded, and blood gas analysis and laboratory tests of perfusate and bile were examined to analyze the function of the diseased livers. Liver tissues before and after NMP were collected for histological analysis., Results: Experiments showed that the system maintained the diseased livers in a physiological state, ensuring stable hemodynamics and a suitable partial pressure of oxygen and carbon dioxide. The results of blood gas analysis and laboratory tests demonstrated a restoration and sustenance of metabolism with minimal damage. Notably, a majority of the diseased livers exhibited bile production continuously, signifying their vivid functional integrity. The pathological characteristics remained stable before and after NMP., Conclusion: We successfully established the machine perfusion system tailored specifically for diseased human whole livers. Through the application of this system, we have developed a novel in vitro model that faithfully recapitulates the main features of human liver disease. This model holds immense promise as an advanced disease modeling platform, offering profound insights into liver diseases and potential implications for research and therapeutic development., (© 2024 The Authors. Artificial Organs published by International Center for Artificial Organ and Transplantation (ICAOT) and Wiley Periodicals LLC.)

Ischemia-reperfusion injury (IRI) is an intrinsic risk associated with liver transplantation. Ex vivo hepatic machine perfusion (MP) is an emerging organ preservation technique that can mitigate IRI, especially in livers subjected to prolonged warm ischemia time (WIT). However, a method to quantify the biological response to WIT during MP has not been established. Previous studies used physiologically based pharmacokinetic (PBPK) modeling to demonstrate that a decrease in hepatic transport and biliary excretion of the tracer molecule sodium fluorescein (SF) could correlate with increasing WIT in situ. Furthermore, these studies proposed intracellular sequestration of the hepatocyte canalicular membrane transporter multidrug resistance-associated protein 2 (MRP2) leading to decreased MRP2 activity (maximal transport velocity; V max ) as the potential mechanism for decreased biliary SF excretion. We adapted an extant PBPK model to account for ex vivo hepatic MP and fit a six-parameter version of this model to control time-course measurements of SF in MP perfusate and bile. We then identified parameters whose values were likely insensitive to changes in WIT and fixed them to generate a reduced model with only three unknown parameters. Finally, we fit the reduced model to each individual biological replicate SF time course with differing WIT, found the mean estimated value for each parameter, and compared them using a one-way ANOVA. We demonstrated that there was a significant decrease in the estimated value of V max for MRP2 at the 30-min WIT. These studies provide the foundation for future studies investigating real-time assessment of liver viability during ex vivo MP. NEW & NOTEWORTHY We developed a computational model of sodium fluorescein (SF) biliary excretion in ex vivo machine perfusion and used this model to assess changes in model parameters associated with the activity of MRP2, a hepatocyte membrane transporter, in response to increasing warm ischemia time. We found a significant decrease in the parameter value describing MRP2 activity, consistent with a role of decreased MRP2 function in ischemia-reperfusion injury leading to decreased secretion of SF into bile.

Ischemia is a major limiting factor in Vascularized Composite Allotransplantation (VCA) as irreversible muscular injury can occur after as early as 4-6 h of static cold storage (SCS). Organ preservation technologies have led to the development of storage protocols extending rat liver ex vivo preservation up to 4 days. Development of such a protocol for VCAs has the added challenge of inherent ice nucleating factors of the graft, therefore, this study focused on developing a robust protocol for VCA supercooling. Rodent partial hindlimbs underwent subnormothermic machine perfusion (SNMP) with several loading solutions, followed by a storage solution with cryoprotective agents (CPA) developed for VCAs. Storage occurred in suspended animation for 24h and VCAs were recovered using SNMP with modified Steen. This study shows a robust VCA supercooling preservation protocol in a rodent model. Further optimization is expected to allow for its application in a transplantation model, which would be a breakthrough in the field of VCA preservation., (Copyright © 2024 Society for Cryobiology. Published by Elsevier Inc. All rights reserved.)

Over the last 50 years, liver transplantation has evolved into a procedure routinely performed in many countries worldwide. Those able to access this therapy frequently experience a miraculous risk-benefit ratio, particularly if they face the imminently life-threatening disease. Over the decades, the success of liver transplantation, with dramatic improvements in early posttransplant survival, has aggressively driven demand. However, despite the emergence of living donors to augment deceased donors as a source of organs, supply has lagged far behind demand. As a result, rationing has been an unfortunate focus in recent decades. Recent shifts in the epidemiology of liver disease combined with transformative innovations in liver preservation suggest that the underlying premise of organ shortage may erode in the foreseeable future. The focus will sharpen on improving equitable access while mitigating constraints related to workforce training, infrastructure for organ recovery and rehabilitation, and their associated costs. Research efforts in liver preservation will undoubtedly blossom with the aim of optimizing both the timing and conditions of transplantation. Coupled with advances in genetic engineering, regenerative biology, and cellular therapies, the portfolio of innovation, both broad and deep, offers the promise that, in the future, liver transplantation will not only be broadly available to those in need but also represent a highly durable life-saving therapy., (Copyright © 2024 American Association for the Study of Liver Diseases.)

The shortage of transplant organs remains a severe global issue. Normothermic machine perfusion (NMP) has the potential to increase organ availability, yet its efficacy is hampered by the inflammatory response during machine perfusion. Mouse liver ischemia-reperfusion injury (IRI) models, discarded human liver models, and porcine marginal liver transplantation models were utilized to investigate whether farnesoid X receptor (FXR) activation could mitigate inflammation-induced liver damage. FXR expression levels before and after reperfusion were measured. Gene editing and coimmunoprecipitation techniques were employed to explore the regulatory mechanism of FXR in inflammation inhibition. The expression of FXR correlates with the extent of liver damage after reperfusion. Activation of FXR significantly suppressed the inflammatory response triggered by IRI, diminished the release of proinflammatory cytokines, and improved liver function recovery during NMP, assisting discarded human livers to reach transplant standards. Mechanistically, FXR disrupts the interaction between p65 and p300, thus inhibiting modulating the nuclear factor kappa-B signaling pathway, a key instigator of inflammation. Our research across multiple species confirms that activating FXR can optimize NMP by attenuating IRI-related liver damage, thereby improving the utilization of marginal livers for transplantation., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)