Donation After Circulatory Death Research Articles

Subnormothermic Oxygenated Machine Perfusion (24 h) in DCD Kidney Transplantation.

Ex vivo kidney perfusion is an evolving platform that demonstrates promise in preserving and rehabilitating the kidney grafts. Despite this, there is little consensus on the optimal perfusion conditions. Hypothermic perfusion offers limited functional assessment, whereas normothermic perfusion requires a more complex mechanical system and perfusate. Subnormothermic machine perfusion (SNMP) has the potential to combine the advantages of both approaches but has undergone limited investigation. Therefore, the present study sought to determine the suitability of SNMP for extended kidney preservation. SNMP at 22-25 °C was performed on a portable device for 24 h with porcine kidneys. Graft assessment included measurement of mechanical parameters and biochemical analysis of the perfusate using point-of-care tests. To investigate the viability of kidneys preserved by SNMP, porcine kidney autotransplants were performed in a donation after circulatory death (DCD) model. SNMP was also compared with static cold storage (SCS). Finally, follow-up experiments were conducted in a subset of human kidneys to test the translational significance of findings in porcine kidneys. In the perfusion-only cohort, porcine kidneys all displayed successful perfusion for 24 h by SNMP, evidenced by stable mechanical parameters and biological markers of graft function. Furthermore, in the transplant cohort, DCD grafts with 30 min of warm ischemic injury demonstrated superior posttransplant graft function when preserved by SNMP in comparison with SCS. Finally, human kidneys that underwent 24-h perfusion exhibited stable functional and biological parameters consistent with observations in porcine organs. These observations demonstrate the suitability and cross-species generalizability of subnormothermic machine perfusion to maintain stable kidney perfusion and provide foundational evidence for improved posttransplant graft function of DCD kidneys after SNMP compared with SCS.

Reduction in pacemaker rates post-heart transplantation with use of organ preservation systems

Abstract Background Approximately 10% of heart transplant recipients require permanent pacemaker (PPM) implantation. (1) Prolonged graft ischaemic time may contribute to conduction system injury and PPM requirement. (2) Ex-vivo preservation of heart allografts at the time of organ retrieval, using either normothermic or hypothermic organ preservation systems (OPS), allows for the reduction of graft ischaemic time which can facilitate long-distance procurements and use of marginal donors including donation after circulatory death (DCD) donors. (3) Purpose We sought to determine if the use of organ preservation systems reduced PPM implantation in heart transplant recipients. Methods This was a single-centre retrospective study of 405 consecutive heart transplant recipients between July 2014 and March 2023. Baseline demographics, utilisation of organ preservation systems, donor ischaemic times, history of graft dysfunction, rejection and chronic allograft vasculopathy were obtained from the medical records. The primary outcome was PPM implantation. Results Of 405 heart transplants performed, an organ preservation system (OPS) was utilised in 118 (29.1%) patients. Normothermic OPS was used in 93/405 (23%) transplants, 90 of which were DCD transplants. Twenty-five of 405 (6.2%) transplants were performed using a hypothermic OPS to facilitate donation after brain death (DBD). The remaining 287 (70.9%) organs underwent cold ischaemic storage (CIS) from retrieval until transplant. Apart from male sex (81% in OPS group versus 69% in the CIS group), there were no significant differences in baseline demographics between the two groups (table 1). Two of 118 (1.7%) patients in the OPS group required PPM implantation, compared to 27/287 (9.4%) in the cold ischaemic storage group (Chi-Square 7.5, p = 0.006). Kaplan-Meier analysis (figure 1) demonstrates a significantly lower rate of PPM implantation in the OPS arm (Log Rank 6.975, p = 0.008). Of the 29 patients who required pacing, 12/29 (41.4%) had AV block and 17/29 (58.6%) had sinus node dysfunction. Thirteen of 29 patients (44.8%) required PPM implantation within 30 days of transplant. Six of 29 patients (20.7%) were pacing dependent at last follow up. Conclusion Heart transplants performed utilising an organ preservation system were associated with lower PPM rates.Table 1.Figure 1.

#1331 PCSK9 inhibitor addition during hypothermic perfusion protects kidney from ischemic damage in a rat model of donation after circulatory death

Abstract Background and Aims PCSK9 inhibitors (PCSK9i) are a new class of cholesterol-lowering drugs that is gaining market share in treating hypercholesterolemia because of their effectiveness in lowering LDL cholesterol and cardiovascular risk, even in patients with kidney disease. In addition to the well-known effect of inhibiting the LDL receptor catabolism, new pharmacological properties are being discovered. Experimental cellular and animal models have showed that PCSK9i reduce apoptosis, pyroptosis and in acute myocardial infarction decrease the infarct area, suggesting their protective role in tissue ischemia. However, so far PCSK9i effect on renal ischemic damage has not yet been studied. The aim of this study was to evaluate the effects of PEP 2-8 (PCSK9i) addition during hypothermic perfusion (HP) on ischemic kidney damage (ID) in a rat model of donation after circulatory death (DCD). Method n. 15 Sprague-Dawley rats were used as DCD donors. Briefly after a midline laparotomy, the left and right retroperitoneal renal areas were exposed, and lumbar arteries were isolated and sectioned; subsequently, the renal arteries and veins were isolated. After 30 min of warm ischemia, induced by aorta clamping, left and right nephrectomies were completed with preservation of the renal hilums. Then the kidneys were perfused with Perf-Gen Solution (100 ml) (Institut Georges Lopez, Lissieu, France) or Perf-Gen solution (100 ml) supplemented with 3ug (10ug/kg) of PEP 2-8. Continuous HP was performed for 6 h at 4 °C. DCD right and left kidneys of each rat were randomized to the following experimental groups: CTRL group: n = 15 DCD rat kidneys perfused with Perf-Gen PEP group: n = 15 DCD rat kidneys perfused with Pef-Gen supplemented with PEP 2-8. Effluent fluid was collected at the beginning (T0) and at the end (T6h) of HP. Glucose and potassium levels were measured in the effluent fluid at T0 and T6h. At T6h the kidneys were splitted into three aliquots; one was fixed in 10% formalin for morphological studies, and the other two were stored in trizol for gene expression studies and at −80 °C for biochemical assays respectively. Tubular ischemic damage (TID) was evaluated at T6 by scoring all tubules observed in at least 10 non-consecutive high-powered fields, as described by Paller (Paller Score). NOX- 4 gene expression was studied by RT-PCR assay. Tissue LDH and ATP levels were measured at T6h. Results PEP 2-8 treated kidneys showed a lower TID score compared to CTRL (PEP 107.0 IQR 90.75-116.0 vs CTRL 134.5 IQR 131.3-155.3 p < 0.005) (Fig. 1). The percentage of tubules with score zero (normal tubules) was higher in PEP than CTRL (PEP 29.0% range % 24.2-39.5 vs CTRL 9.5% range % 5.5-12.0, p < 0.001). The percentage of tubules with necrosis was lower in PEP than CTRL (PEP 5.5% range % 3.2-10.5 vs CTRL 12.5% range % 9.0-15.7, p < 0.005). Expression of NOX-4 gene, known inducer of apoptosis, was lower in PEP compared to CTRL (p < 0.05) Tissue ATP content was higher in PEP than CTRL (PEP 0.031 ± 0.01 vs CTRL 0.025 ± 0.006 p < 0.05). In tissue samples at T6 LDH was lower in PEP than CTRL (PEP 554.8 ± 164.7 vs CTRL 742.4 ± 256.7 p < 0.05) conversely the potassium release in effluent was significant only in CTRL (T6 vs T0 p < 0.01), according to TID score results. During HP, PEP 2-8 treated kidneys released more glucose in the effluent than CTRL kidneys (PEP 35.4 IQR 12.3-82.9 vs CTRL 12.3 IQR 7.1-70.5 p < 0.01). Conclusion Our preliminary results show that PEP 2-8 added to Perf-Gen solution during HP protects kidneys from ID, preserving energy metabolism in rat DCD model. To the best of our knowledge, this is the first evidence of protective role of PCSK9 inhibition in pre-transplant renal conditioning and potentially it could be used in conditioning other organs (liver, lung). However, further studies are necessary to understand the mechanisms underlying PCSK9i effect on energy metabolism and neoglucogenesis.

#1446 PCSK9 inhibitor addition during hypothermic perfusion protects kidney from ischemic damage in a rat model of donation after circulatory death

Abstract Background and Aims PCSK9 inhibitors (PCSK9i) are a new class of cholesterol-lowering drugs that is gaining market share in treating hypercholesterolemia because of their effectiveness in lowering LDL cholesterol and cardiovascular risk, even in patients with kidney disease. In addition to the well-known effect of inhibiting the LDL receptor catabolism, new pharmacological properties are being discovered. Experimental cellular and animal models have showed that PCSK9i reduce apoptosis, pyroptosis and in acute myocardial infarction decrease the infarct area, suggesting their protective role in tissue ischemia. However, so far PCSK9i effect on renal ischemic damage has not yet been studied. The aim of this study was to evaluate the effects of PEP 2-8(PCSK9i) addition during hypothermic perfusion (HP) on ischemic kidney damage (ID) in a rat model of donation after circulatory death (DCD). Method n. 15 Sprague-Dawley rats were used as DCD donors. Briefly after a midline laparotomy, the left and right retroperitoneal renal areas were exposed, and lumbar arteries were isolated and sectioned; subsequently, the renal arteries and veins were isolated. After 30 min of warm ischemia, induced by aorta clamping, left and right nephrectomies were completed with preservation of the renal hilums. Then the kidneys were perfused with Perf-Gen Solution (100 ml) (Institut Georges Lopez, Lissieu, France) or Perf-Gen solution (100 ml) supplemented with 3ug (10ug/kg) of PEP 2-8. Continuous HP was performed for 6 h at 4 °C. DCD right and left kidneys of each rat were randomized to the following experimental groups: CTRL group: n = 15 DCD rat kidneys perfused with Perf-Gen PEP group: n = 15 DCD rat kidneys perfused with Pef-Gen supplemented with PEP 2-8. Effluent fluid was collected at the beginning (T0) and at the end (T6h) of HP. Glucose and potassium levels were measured in the effluent fluid at T0 and T6h. At T6h the kidneys were splitted into three aliquots; one was fixed in 10% formalin for morphological studies, and the other two were stored in trizol for gene expression studies and at −80 °C for biochemical assays respectively. Tubular ischemic damage (TID) was evaluated at T6 by scoring all tubules observed in at least 10 non-consecutive high-powered fields, as described by Paller (Paller Score). NOX- 4 gene expression was studied by RT-PCR assay. Tissue LDH and ATP levels were measured at T6h. Results PEP 2-8 treated kidneys showed a lower TID score compared to CTRL (PEP 107.0 IQR 90.75-116.0 vs CTRL 134.5 IQR 131.3-155.3 p < 0.005) (Fig. 1). The percentage of tubules with score zero (normal tubules) was higher in PEP than CTRL (PEP 29.0% range % 24.2-39.5 vs CTRL 9.5% range % 5.5-12.0, p < 0.001). The percentage of tubules with necrosis was lower in PEP than CTRL (PEP 5.5% range % 3.2-10.5 vs CTRL 12.5% range % 9.0-15.7, p < 0.005). Expression of NOX-4 gene, known inducer of apoptosis, was lower in PEP compared to CTRL (p < 0.05) Tissue ATP content was higher in PEP than CTRL (PEP 0.031 ± 0.01 vs CTRL 0.025 ± 0.006 p < 0.05). In tissue samples at T6 LDH was lower in PEP than CTRL (PEP 554.8 ± 164.7 vs CTRL 742.4 ± 256.7 p < 0.05) conversely the potassium release in effluent was significant only in CTRL (T6 vs T0 p < 0.01), according to TID score results. During HP, PEP 2-8 treated kidneys released more glucose in the effluent than CTRL kidneys (PEP 35.4 IQR 12.3-82.9 vs CTRL 12.3 IQR 7.1-70.5 p < 0.01). Conclusion Our preliminary results show that PEP 2-8 added to Perf-Gen solution during HP protects kidneys from ID, preserving energy metabolism in rat DCD model. To the best of our knowledge, this is the first evidence of protective role of PCSK9 inhibition in pre-transplant renal conditioning and potentially it could be used in conditioning other organs (liver, lung). However, further studies are necessary to understand the mechanisms underlying PCSK9i effect on energy metabolism and neoglucogenesis.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2022 Part I: Lung Transplantation

These highlights focus on the research in lung transplantation (LTX) that has been published in the year 2022 and includes the assessment and optimization of candidates for LTX, donor optimization, the use of organs from donation after circulatory death (DCD), and outcomes when using marginal or novel donors, recipient factors affecting LTX, including age, disease, the use of extracorporeal life support (ECLS), and special situations, such as COVID-19, pediatric LTX, and retransplantation. The remainder of the article focuses on the perioperative management of LTX, including the perioperative risk factors for acute renal failure (AKI), and the incidence and management of phrenic nerve injury, delirium, and pain and the postoperative management of hyperammonemia, early postoperative infections, and the use of donor-derived cell-free deoxynucleic acid (DNA) to detect rejection.

Normothermic Ex Vivo Heart Perfusion With Exosomes From Human Umbilical Cord Mesenchymal Stem Cells Improves Graft Function in Donation After Circulatory Death Hearts.

This study aimed to investigate the cardioprotective effect of exosomes derived from human umbilical cord mesenchymal stem cells on donation after circulatory death (DCD) hearts preserved with normothermic ex vivo heart perfusion (EVHP) in a rat heart transplantation model. Thirty-two male Lewis rats were divided into 2 groups: the control group and the exosome group. The donor-heart rats were subjected to the DCD procedure by suffering a 15-min warm ischemia injury, subsequently preserved with EVHP for 90 min, and then transplanted into recipients via abdominal heterotopic heart transplantation. Vehicle or exosome was added into the perfusate of normothermic EVHP in the control or exosome group. We evaluated left ventricular graft function, myocardial inflammation, and myocardial apoptosis of the donor heart 1.5 h after heart transplantation. Furthermore, we investigate the alternation of myocardial gene expression in the donor hearts between both groups by transcriptome sequencing. The treatment with exosome significantly enhanced cardiac function through increasing left ventricular developed pressure, dp/dtmax, and dp/dtmin of DCD hearts at 90 min after heart transplantation compared with the control group. The myocardial cells in the exosome group exhibited an orderly arrangement without obvious edema. Furthermore, exosome added into perfusate in the exosome group significantly attenuated the level of inflammatory response and apoptosis. Transcriptome sequencing and RT-qPCR showed the phosphoinositide 3-kinase/protein kinase B pathway was activated after exosome treatment. Normothermic EVHP combined with exosome can be a promising and novel DCD heart preservation strategy, alleviating myocardial ischemia-reperfusion injury in the DCD heart.

Kidney transplant utilising donors after circulatory death: The first report from the African continent.

At Groote Schuur Hospital in Cape Town, South Africa, the number of deceased organ donors has declined over the past 2 decades, necessitating a more liberal approach to donor selection. In 2007, measures to expand the deceased kidney donor pool were implemented, including an HIV positive-to-positive transplant programme and the utilisation of extended-criteria donors as well as donors after circulatory death (DCDs). To report on our institutional experience with DCD kidney transplants and to encourage this approach among other African centres to improve access to transplantation. An observational cohort study of consecutive DCD kidney transplants at Groote Schuur Hospital over a 17-year period was performed. Primary endpoints were 1-, 2- and 5-year graft and patient survival. Secondary endpoints included the incidence of delayed graft function (DGF), 30-day morbidity, length of stay, and donor and recipient clinical characteristics. Fifteen DCD procurements were performed, with no kidneys discarded. Thirty kidney transplants were performed, with a median (interquartile range) cold ischaemic time of 11.5 (8 - 14) hours. The incidence of DGF was 60.0%, and 30-day morbidity (other than DGF) was 20.0%. Graft survival at 1, 2 and 5 years was 100%, 96.0% and 73.7%, respectively. Patient survival at 1, 2 and 5 years was 93.3%, 93.3% and 88.4%, respectively. Long-term graft and patient survival was comparable with the international literature. DCD may present a unique opportunity to expand deceased donation throughout Africa, particularly in areas affected by a lack of brain death legislation and religious or cultural objections to donation after brain death.

Donor-derived cell-free DNA, gene expression profile, and acute rejection in donation after circulatory death (DCD) heart transplant recipients

BackgroundAcute rejection (AR) is a leading cause of early morbidity and mortality in heart transplant (HTx) recipients. There is limited data in donor after circulatory death (DCD) HTx recipients where ischemia reperfusion injury may contribute to development of AR and may be detected early with non-invasive biomarkers such as donor-derived cell-free DNA (dd-cfDNA) and gene expression profile (GEP). The goal of this study is to compare dd-cfDNA, GEP and rejection outcomes in DCD and donor after brain death (DBD) HTx recipients. MethodsThis single-center, retrospective study included DCD and DBD HTx recipients from January 2020 to September 2022. Patients were excluded from the study if dd-cfDNA and GEP were not available. The CareDx HeartCare platform was used to obtain dd-cfDNA (AlloSure-Heart) and GEP (AlloMap) with the highest values for each patient recorded at 6 and 12 months. The mean values for these non-invasive markers were compared between DCD and DBD groups. Patients were followed for clinical outcomes, including treated AR, coronary allograft vasculopathy (CAV) and death, through September 2023. ResultsA total of 156 HTx patients were included with 50 DCD and 106 DBD recipients. Baseline characteristics were similar between DCD and DBD recipients including mean age (58.5 years vs 56.9 years, p = 0.48), male sex (82% vs 76%, p = 0.56) and Caucasian race (46% vs 43%, p = 0.78). There were no significant differences in mean AlloSure-Heart at 6 and 12 months between DCD and DBD recipients. AlloMap was significantly lower at 6 months (p = 0.04), but not at 12 months between DCD and DBD recipients. With respect to clinical outcomes at 1 year, there were no significant differences in treated AR (22% vs 14%, p = 0.32), ISHLT grade ≥ 2 CAV (0 vs 4%, p = 0.44) or mortality (2% vs 0%, p = 0.69) between DCD and DBD recipients. ConclusionsIn this single center study, there were no significant differences in mean dd-cfDNA and treated AR at 1 year between DCD and DBD HTx recipients. There was a significant increase in mean GEP at 6 months, but not at 12 months in the DBD cohort. Overall, there does not appear to be clinically significant cardiac allograft injury related to DCD as measured by non-invasive markers. Further work is needed to confirm these findings.

Enhancing the usability of older DCD donors through strategic approaches in liver transplantation in the United States.

The use of older donors after circulatory death (DCD) for liver transplantation (LT) has increased over the past decade. This study examined whether outcomes of LT using older DCD (≥50y) have improved with advancements in surgical/perioperative care and normothermic machine perfusion (NMP) technology. A total of 7602 DCD LT cases from the United Network for Organ Sharing database (2003-2022) were reviewed. The impact of older DCD donors on graft survival was assessed using the Kaplan-Meier and HR analyses. In all, 1447 LT cases (19.0%) involved older DCD donors. Although there was a decrease in their use from 2003 to 2014, a resurgence was noted after 2015 and reached 21.9% of all LTs in the last 4 years (2019-2022). Initially, 90-day and 1-year graft survivals for older DCDs were worse than younger DCDs, but this difference decreased over time and there was no statistical difference after 2015. Similarly, HRs for graft loss in older DCD have recently become insignificant. In older DCD LT, NMP usage has increased recently, especially in cases with extended donor-recipient distances, while the median time from asystole to aortic cross-clamp has decreased. Multivariable Cox regression analyses revealed that in the early phase, asystole to cross-clamp time had the highest HR for graft loss in older DCD LT without NMP, while in the later phases, the cold ischemic time (>5.5h) was a significant predictor. LT outcomes using older DCD donors have become comparable to those from young DCD donors, with recent HRs for graft loss becoming insignificant. The strategic approach in the recent period could mitigate risks, including managing cold ischemic time (≤5.5h), reducing asystole to cross-clamp time, and adopting NMP for longer distances. Optimal use of older DCD donors may alleviate the donor shortage.

Noteworthy in Cardiothoracic Surgery 2023.

Noteworthy in Cardiothoracic Surgery 2023 summarizes a few of the most high-impact trials and provocative trends in cardiothoracic surgery and transplantation this past year. Transplantation using organs procured from donation after circulatory death (DCD) continues to increase, and the American Society of Transplant Surgeons released recommendations on best practices in 2023. We review a summary of data on the impact of DCD on heart and lung transplantation. There has been increased interest in extracorporeal life support (ECLS), particularly after the COVID-19 pandemic, and we review the results of the highly discussed ECLS-SHOCK trial, which randomized patients in cardiogenic shock with planned revascularization to ECLS vs usual care. With improving survival outcomes in complex aortic surgery, there is a need for higher-quality evidence to guide which cooling and cerebral perfusion strategies may optimize cognitive outcomes in these patients. We review the short-term outcomes of the GOT ICE trial (Cognitive Effects of Body Temperature During Hypothermic Circulatory Arrest), a multicenter, randomized controlled trial of three different nadir temperatures, evaluating outcomes in cognition and associated changes in functional magnetic resonance imaging. Finally, both the Society of Thoracic Surgeons (STS) and the American College of Cardiology, American Heart Association, American College of Chest Physicians and Heart Rhythm Society (ACC/AHA/ACCP/HRS) updated atrial fibrillation guidelines in 2023, and we review surgically relevant updates to the guidelines and the evidence behind them.

Effects of Trehalose Preconditioning on H9C2 Cell Viability and Autophagy Activation in a Model of Donation after Circulatory Death for Heart Transplantation.

Donation after circulatory death (DCD) is a promising strategy for alleviating donor shortage in heart transplantation. Trehalose, an autophagy inducer, has been shown to be cardioprotective in an ischemia-reperfusion (IR) model; however, its role in IR injury in DCD remains unknown. In the present study, we evaluated the effects of trehalose on cardiomyocyte viability and autophagy activation in a DCD model. In the DCD model, cardiomyocytes (H9C2) were exposed to 1 h warm ischemia, 1 h cold ischemia, and 1 h reperfusion. Trehalose was administered before cold ischemia (preconditioning), during cold ischemia, or during reperfusion. Cell viability was measured using the Cell Counting Kit-8 after treatment with trehalose. Autophagy activation was evaluated by measuring autophagy flux using an autophagy inhibitor, chloroquine, and microtubule-associated protein 1A/1B light chain 3 B (LC3)-II by western blotting. Trehalose administered before the ischemic period (trehalose preconditioning) increased cell viability. The protective effects of trehalose preconditioning on cell viability were negated by chloroquine treatment. Furthermore, trehalose preconditioning increased autophagy flux. Trehalose preconditioning increased cardiomyocyte viability through the activation of autophagy in a DCD model, which could be a promising strategy for the prevention of cardiomyocyte damage in DCD transplantation.

National Trends in Utilization of Normothermic Machine Perfusion in DCD Liver Transplantation.

In liver transplantation, advances in ex situ normothermic machine perfusion (NMP) have improved outcomes compared with traditional static cold storage (SCS) in donation after circulatory death (DCD) organs. We aimed to characterize trends in the utilization of NMP versus SCS in DCD liver transplantation in the United States. This retrospective cohort study used data from the United Network for Organ Sharing database to identify recipient-donor adult liver transplant pairs from DCD donors from January 2016 to June 2022. Utilization of NMP and changes in donor risk index (DRI) and components between NMP and SCS were assessed across transplant year eras (2016-2018, 2019-2020, and 2021-2022). Statistical comparisons were made using the Kruskal-Wallis test or the chi-square test. A total of 3937 SCS and 127 NMP DCD donor transplants were included. Utilization of NMP ranged from ~0.4% to 3.5% from 2016 to 2021 and rose significantly to 11.2% in early 2022. Across transplant eras, median DRI increased significantly for SCS and NMP, but the magnitude of the increase was larger for NMP. With NMP DCDs, there were significant increases in median donor age, national share proportion, and "cold ischemic time" over time. Finally, there was a shift toward including higher DRI donors and higher model for end-stage liver disease score transplant recipients with NMP in later transplant eras. In recent years, NMP utilization has increased and expanded to donors with higher DRI and recipients with higher model for end-stage liver disease score at transplant, suggesting increasing familiarity and risk tolerance with NMP technology. As NMP remains a relatively new technique, ongoing study of patient outcomes, organ allocation practices, and utilization patterns is critical.

Metabolic Considerations in Direct Procurement and Perfusion Protocols with DCD Heart Transplantation.

Heart transplantation with donation after circulatory death (DCD) provides excellent patient outcomes and increases donor heart availability. However, unlike conventional grafts obtained through donation after brain death, DCD cardiac grafts are not only exposed to warm, unprotected ischemia, but also to a potentially damaging pre-ischemic phase after withdrawal of life-sustaining therapy (WLST). In this review, we aim to bring together knowledge about changes in cardiac energy metabolism and its regulation that occur in DCD donors during WLST, circulatory arrest, and following the onset of warm ischemia. Acute metabolic, hemodynamic, and biochemical changes in the DCD donor expose hearts to high circulating catecholamines, hypoxia, and warm ischemia, all of which can negatively impact the heart. Further metabolic changes and cellular damage occur with reperfusion. The altered energy substrate availability prior to organ procurement likely plays an important role in graft quality and post-ischemic cardiac recovery. These aspects should, therefore, be considered in clinical protocols, as well as in pre-clinical DCD models. Notably, interventions prior to graft procurement are limited for ethical reasons in DCD donors; thus, it is important to understand these mechanisms to optimize conditions during initial reperfusion in concert with graft evaluation and re-evaluation for the purpose of tailoring and adjusting therapies and ensuring optimal graft quality for transplantation.

Outcomes of Heart Transplantation From Donation After Circulatory Death: An Up-to-date Systematic Meta-analysis.

Donation after circulatory death (DCD) heart transplantation (HTx) significantly expands the donor pool and reduces waitlist mortality. However, high-level evidence-based data on its safety and effectiveness are lacking. This meta-analysis aimed to compare the outcomes between DCD and donation after brain death (DBD) HTxs. Databases, including MEDLINE, Embase, CINAHL, and the Cochrane Central Register of Controlled Trials, were systematically searched for randomized controlled trials and observational studies reporting the outcomes of DCD and DBD HTxs published from 2014 onward. The data were pooled using random-effects models. Risk ratios (RRs) with 95% confidence intervals (CIs) were used as the summary measures for categorical outcomes and mean differences were used for continuous outcomes. Twelve eligible studies were included in the meta-analysis. DCD HTx was associated with lower 1-y mortality rate (DCD 8.13% versus DBD 10.24%; RR = 0.75; 95% CI, 0.59-0.96; P = 0.02) and 5-y mortality rate (DCD 14.61% versus DBD 20.57%; RR = 0.72; 95% CI, 0.54-0.97; P = 0.03) compared with DBD HTx. Using the current DCD criteria, HTx emerges as a promising alternative to DBD transplantation. The safety and feasibility of DCD hearts deserve further exploration and investigation.

Cell-specific Extracellular Vesicles and Their miRNA Cargo Released Into the Organ Preservation Solution During Cold Ischemia Storage as Biomarkers for Liver Transplant Outcomes.

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. 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. 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. 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.

(353) - Donation After Circulatory Death (DCD) Lung Transplant Outcomes in the United States

(353) - Donation After Circulatory Death (DCD) Lung Transplant Outcomes in the United States

Macrophage-derived extracellular vesicles alter cardiac recovery and metabolism in a rat heart model of donation after circulatory death.

Conditions to which the cardiac graft is exposed during transplantation with donation after circulatory death (DCD) can trigger the recruitment of macrophages that are either unpolarized (M0) or pro-inflammatory (M1) as well as the release of extracellular vesicles (EV). We aimed to characterize the effects of M0 and M1 macrophage-derived EV administration on post-ischaemic functional recovery and glucose metabolism using an isolated rat heart model of DCD. Isolated rat hearts were subjected to 20 min aerobic perfusion, followed by 27 min global, warm ischaemia or continued aerobic perfusion and 60 min reperfusion with or without intravascular administration of EV. Four experimental groups were compared: (1) no ischaemia, no EV; (2) ischaemia, no EV; (3) ischaemia with M0-macrophage-dervied EV; (4) ischaemia with M1-macrophage-derived EV. Post-ischaemic ventricular and metabolic recovery were evaluated. During reperfusion, ventricular function was decreased in untreated ischaemic and M1-EV hearts, but not in M0-EV hearts, compared to non-ischaemic hearts (p < 0.05). In parallel with the reduced functional recovery in M1-EV versus M0-EV ischaemic hearts, rates of glycolysis from exogenous glucose and oxidative metabolism tended to be lower, while rates of glycogenolysis and lactate release tended to be higher. EV from M0- and M1-macrophages differentially affect post-ischaemic cardiac recovery, potentially by altering glucose metabolism in a rat model of DCD. Targeted EV therapy may be a useful approach for modulating cardiac energy metabolism and optimizing graft quality in the setting of DCD.

(4) - Early Outcomes and Trends in Use of Donation After Circulatory Death (DCD) Donors for Multi-Organ Heart Transplantation (HT) in US

(4) - Early Outcomes and Trends in Use of Donation After Circulatory Death (DCD) Donors for Multi-Organ Heart Transplantation (HT) in US

(871) - Donor Derived Cell Free DNA, Gene Expression Profiles and Acute Rejection in Donation After Circulatory Death (DCD) Heart Transplant Recipients

(871) - Donor Derived Cell Free DNA, Gene Expression Profiles and Acute Rejection in Donation After Circulatory Death (DCD) Heart Transplant Recipients

Financial impact of donation after circulatory death heart transplantation: A single-center analysis.

Clinical success of donation after circulatory death (DCD) heart transplantation is leading to growing adoption of this technique. In comparison to procurement from a brain-dead donor, DCD requires additional resources. The economic impact of DCD heart transplantation from the hospital perspective is not well known. We compared the financial data of patients who received DCD allografts to those who received a DBD organ at our institution from January 1, 2021 to December 31, 2022. We also compared the cost of ex-situ machine perfusion to in-situ organ perfusion employed during DCD recovery. We performed 58 DBD and 22 DCD heart-alone transplantations during the study period. Out of 22 DCD grafts, 16 were recovered with thoracoabdominal normothermic regional perfusion (TA-NRP) and six with direct procurement followed by normothermic machine perfusion (DP-NMP). The contribution margin per case for DBD versus DCD was $234,362 and $235,440 (P=.72). The direct costs did not significantly differ between the two groups ($171,949 and 186,250; P=.49). In comparing the two methods of procuring hearts from DCD donors, the direct cost of TA-NRP was $155,955 in comparison to $223,399 for DP-NMP (P=.21). This difference translated into a clinically meaningful but not statistically significant greater contribution margin for TA-NRP ($242, 657vs. $175,768; P=.34). Our data showed that the adoption of DCD procurement did not have a negative financial impact on the contribution margin in our institution. Programs considering starting DCD heart transplantation, and those who are currently performing DCD procurement should evaluate their own financial situation.