Graft Dysfunction Research Articles

Postoperative conditions of rehabilitative interest in lung transplantation: a systematic review.

Lung transplantation is an elective treatment option for end-stage respiratory diseases in which all medical therapy options have been exhausted. The current study aimed to identify updated information on the postoperative conditions that may impair rehabilitation after lung transplantation and to provide specific considerations of their clinical relevance during the recovery process. The present study is a systematic review conducted by searching three primary databases: the United States National Library of Medicine PubMed system, Scopus, and the Cochrane Library. The databases were searched for articles published from database inception until May 2024; at the end of the selection process, 27 documents were included in the final analysis. The retrieved material identified 19 conditions of rehabilitative interest that potentially affect the postoperative course: graft dysfunction, dysphagia, postsurgical pain, cognitive impairment, chronic lung allograft dysfunction-bronchiolitis obliterans syndrome, phrenic nerve injury, delayed extracorporeal membrane oxygenation weaning, airway clearance, refractory hypoxemia, mediastinitis, reduced oxidative capacity, sternal dehiscence, coronavirus disease 2019 (COVID-19), gastroparesis, ossification of the elbow, Takotsubo cardiomyopathy, airway dehiscence, recurrent pleural effusion, and scapular prolapse. Although some patients are not amenable to rehabilitation techniques, others can significantly improve with rehabilitation.

Stratification risk computation of primary graft gysfunction in heart transplant recipients on a smartphone application

Abstract Introduction There are no standardized guidelines for helping graft allocation in heart transplant (HTx) and accepting transplants from marginal donors and donors after circulatory arrest make decision making even more complex and time consuming than ever. The organ allocation process should include a risk analysis for primary graft dysfunction (PGD) that represents the most dreadful complication of HTx. There are 3 score systems validated to predict PGD but none has clear superior predictive capability compared to the others and the complexity of score computation potentially discourage their clinical use. A score integrating all the variables presented in a user-friendly format should improve efficacy and safeness of the organ allocation process. Methods Severe PGD defined as need for temporary mechanical circulatory support (ECMO) in the first 24 hours following HTx was considered the end-point for risk stratification computation. As a derivation cohort we used meta-analytic approach for identifying variables that are independently associated to severe PGD. The overall prevalence of each variable was determined to define the absolute risk increase value in presence of each factor. We then created a scoring system applying multivariate logistic regression model. As a validation cohort we studied the performance of the score in a retospective series of HTx performed at our institution from 2013 to 2022. We used C statistic equivalent to the area under a receiver-operating characteristic curve for dichotomous outcomes. Values above 0.7 were considered acceptable. We eventually developed an application for smartphone for risk computation. Results On 64 papers screened, 5 studies were considered eligible for the derivation cohort definition. Cumulative number of patients considered was 10’175 with an incidence of severe PGD of 7.1% (CI 5.3 - 10.4) and a 30-day mortality of 41%. 13 variables were identified (table 1). The ROC curve predicted the use of ECMO with the specificity and the sensitivity of 0,81 and 0,92 respectively. We have included in the validation cohort 128 out of 150 transplanted patients, excluding pediatric and double organs transplants. The mean donor age was 45 +/- 12,4 years, 72 (54%) were men. The mean recipient age was 57 +/- 9,3; 92 were men; 32 recipients (25%) needed ECMO support within 24 hours post-transplant; 75% of the donors in the ECMO group were > 40 y.o.; 30 days mortality was 3.1% and 6,2% in the non-ECMO and ECMO group respectively. We validated the model on our cohort defying a binary outcome (ECMO yes/no). Conclusion Clinicians fill donor, recipient and surgical parameters in user-friendly smartphone application identifying patients that are most likely to need ECMO support post HTx. The decision-making process during organ allocation evolves from what was once little more than personal experience and intuition to a reliable evidence-based method based on personalized risk prediction.Table 1

Role of pericoronary adipose tissue inflammation at CCTA after heart transplantation as non-invasive diagnostic tool of cardiac rejection and predictor of major adverse cardiovascular events

Abstract Background Long-term survival of heart transplanted (HT) patients is challenged by cardiac rejection and cardiac allograft vasculopathy (CAV). Until now, there are no established biomarkers for graft dysfunction, and the conventional approach for cardiac rejection surveillance is through the endomyocardial biopsy (EMB), an invasive and costly procedure. Purpose This study investigates the prognostic value of the pericoronary Fat Attenuation Index (FAI) and its role as a marker of inflammation and rejection in HT recipients. Methods A double-center observational retrospective study was conducted on a cohort of HT patients who underwent coronary computed tomography angiography (CCTA) between January 2016 and December 2022. FAI was measured with dedicated software and using the cut-off described in literature, we considered each coronary as "inflamed" if FAI was ≥ - 70,1 HU and "not inflamed" if FAI was < - 70,1 HU. Then, based on the number of inflamed coronary arteries for each patient, we divided the population into two comparison groups: high inflammatory (high INF) phenotype (alle three coronary arteries inflamed) and low inflammatory (low INF) phenotype (at least one coronary artery not inflamed). The primary endpoint was a composite of all-cause mortality, acute myocardial infarction, urgent revascularization and heart failure hospitalization. Furthermore, we investigated the correlation between FAI and cardiac rejection by looking for T cell-mediated rejection (TCMR) and antibody-mediated rejection (AMR) through EMB performed no more than six months before or after CCTA. Results A total of 101 HT patients were included; of this group 58 patients underwent EMBs within six months after or before the CCTA. The median duration of follow-up was 28 months. The composite endpoint occurred in 17 patients (16.8%). We documented 26 significative cardiac rejection episodes, 14 TCMR ≥ 2R and 12 AMR. The composite endpoint was achieved in 37.9% of patients with high INF phenotype compared to 8.3% with low INF phenotype (p < 0.001). In the multivariate analysis, the high INF phenotype remained an independent predictor of the composite endpoint in our population (HR: 10.5; 95% CI: 1.88-58.71; p = 0.007). Patients with TCMR and AMR had significantly higher FAI values. High INF phenotype correlated with the presence of ACR ≥ 2R (55.0% vs 7.9%, p < 0.001) and AMR (55.0% vs 2.6%, p < 0.001). Conclusion In HT patients, FAI is an independent predictor of major cardiovascular events. It is also associated with TCMR and AMR within six months from CCTA. FAI, therefore, may offer a non-invasive approach to stratify the prognosis of HT patients and serve as a valuable inflammatory biomarker for early diagnosis of cardiac rejection, supporting the use of CCTA in this setting of patients.Correlation FAI and MACECorrelation FAI and cardiac rejection

Evaluation and Management of Urological Complications Following Pediatric Kidney Transplantation: Experience from a Single Tertiary Center

Background/Objectives: Kidney transplantation is the treatment of choice for children with end-stage renal disease (ESRD), but its outcome can be affected by urological complications, with incidence rates of 2.5–25%. The aim of this study was to evaluate the occurrence of urological complications and their management in a cohort of pediatric kidney transplant recipients. Materials and Methods: A retrospective analysis on 178 patients who received a renal transplant at our Pediatric Kidney Transplant Center between 2011 and 2023 was conducted. Demographic and clinical data were analyzed. Urological complications were categorized as early, intermediate, or late based on their onset time. Results: Out of 178 patients, 28 (15.7%) experienced urological complications. Most patients (61%) had a pre-existing uropathy. Early complications (7–30 days) were all obstructive, namely, ureterovesical junction obstruction and perirenal collections. Intermediate complications (1–3 months) comprised ureteral stenosis, symptomatic vesicoureteral reflux (VUR), and obstructive lymphocele. Late complications (>3 months) included symptomatic VUR and ureteral stenosis, with one case leading to ureteral rupture. Early complications were often detected due to acute graft dysfunction, while late ones were mainly identified during routine clinical, laboratory, or ultrasound follow-up. Urological complications requiring surgical or endoscopic therapy were 13.4%. Most ureteral stenoses were treated with initial endoscopic stents, followed by definitive surgery. VUR was treated with endoscopic correction with a high success rate (75%), while open surgery was reserved for cases where initial treatments failed or complications recurred. No clear correlations were found between patient characteristics and risk of urological complication. Urological complications required multiple diagnostic procedures and therapeutic interventions (+2.5 admissions in mean and approximately +EUR 24,000) compared to an uncomplicated post-transplant course. However, they did not significantly impact transplant outcomes, with a graft survival rate comparable to that of the control group. Conclusions: Regular post-transplant follow-up is crucial, especially for patients with known risk factors, to allow for timely detection and treatment of urological complications, avoiding detrimental effects on graft function and improving transplantation outcomes.

They Deserve to Live: Impact of the Berlin Heart EXCOR on Small Children's Heart Transplant Waitlist in Low-Resource Settings.

Background: In newly emerging economy countries, the shortage of pediatric donor hearts and poor healthcare infrastructure poses a significant challenge. Although mechanical circulatory support (MCS) has been proven effective in enhancing heart transplant waiting list outcomes, economic barriers hinder its widespread adoption. Methods: A single-center retrospective study reviewed children under 10 kg on the heart transplant (HTx) list from 2012 to 2023. Elective or priority status was assigned based on their clinical condition at the time of transplant. In cases of clinical decompensation, centrifugal pump and extracorporeal membrane oxygenation, transitioned to the Berlin Heart EXCOR (BHE) pediatric ventricular assist device (VAD) was employed. Pre- and post-HTx outcomes were analyzed with descriptive statistics, Cox regression, and competing survival risks. Results: Out of 81 infants on the HTx list, 61.7% (50/81) were in critical condition. The median wait time was 224 days, and 34% (28/81) died while waiting. Out of 37 transplanted patients, 6 (16%) had graft dysfunction, and 10 (27%) had acute renal injury. Survival to discharge was 84% (31/37). Patients who received the BHE exhibited higher chances of receiving a transplant (hazard ratio: 2.3; 95% confidence interval: 1.2-4.6; P = .01). Priority status or MCS use did not significantly impact mortality post-transplant. Conclusion: Advanced MCS technologies can potentially reduce the mortality risk on the pediatric HTx waitlist. The findings highlight the significant waiting time for HTx and the critical role of the BHE in improving outcomes in children, particularly those under 10 kg. The results advocate for the adoption of ventricular assist devices as a viable interim solution to bridge critically ill children to HTx, ultimately enhancing their chances of survival despite limited donor heart availability.

Lobar graft evaluation in cadaveric lobar lung redo transplantation after living-donor lobar lung transplantation: a case report

BackgroundLung transplantation is a vital option for patients with end-stage lung disease. However, it faces a significant challenge due to the shortage of compatible donors, which particularly affects individuals with small chest cavities and pediatric patients. The novel approach of cadaveric lobar lung transplantation is a promising solution to alleviate the donor shortage crisis. Both the mid-term and long-term outcomes of lobar lung transplantation are comparable to those of standard lung transplantation. However, patients undergoing lobar lung transplantation reported a significantly higher rate of primary graft dysfunction compared to patients undergoing standard lung transplantation. Therefore, careful donor selection is critical to improve outcomes after lobar transplantation. However, no established method exists to evaluate each lung lobar graft of deceased donors. This case report describes a case of cadaveric lobar lung transplantation to overcome size mismatch and donor shortage, with particular emphasis on lobar graft evaluation.Case presentationA 39-year-old woman with scleroderma-related respiratory failure was listed for deceased donor lung transplantation due to a rapidly progressing disease. Faced with a long waiting list and impending mortality, she underwent bilateral living-donor lobar lung transplantation donated by her relatives. Post-transplant complications included progressive pulmonary vein obstruction and pleural effusion, which ultimately required retransplantation. An oversized donor with pneumonia in the bilateral lower lobes was allocated. Lung ultrasound was used to evaluate each lung lobar graft during procurement. The right upper and middle lobes and left upper lobe were confirmed to be transplantable, and lobar lung redo transplantation was performed. The patient’s post-transplant course was uneventful, and she was discharged home and returned to her daily activities.ConclusionsThis case highlights the clinical impact of cadaveric lobar lung transplantation as a feasible and effective strategy to overcome the shortage of donor lungs, especially in patients with small thoracic cavities. By establishing donor lung evaluation techniques and overcoming anatomical and logistical challenges, cadaveric lobar lung transplantation can significantly expand the donor pool and offer hope to those previously considered ineligible for transplantation.

Cold ischemia time alters cell-type specific senescence leading to loss of cellular integrity in mouse lungs

Purpose: Ischemia-reperfusion injury (IRI) is a major challenge in lung transplantation often causing graft dysfunction and chronic airway illnesses in recipients. To prevent potential transplant related complications, strict guidelines were put in place to choose viable donor lungs with minimal risk of IRI. These regulations deem most of the donor organs unfit for transplant which then are donated for research to understand the mechanisms of health and diseases in human. However, resected organs that are being transported undergo cold ischemia that can negatively affect the tissue architecture and other cellular functions under study. Thus, it is important to assess how cold ischemia time (CIT) affects the physiological mechanism. In this respect, we are interested in studying how CIT affects cellular senescence in normal aging and various pulmonary pathologies. We thus hypothesized that prolonged CIT exhibits cell-type specific changes in lung cellular senescence in mice. Methods: Lung lobes from C57BL/6J (n = 5–8) mice were harvested and stored in UW Belzer cold storage solution for 0, 4-, 9-, 12-, 24-, and 48-h CIT. Lung cellular senescence was determined using fluorescence (C12FdG) assay and co-immunolabelling was performed to identify changes in individual cell types. Results: We found a rapid decline in the overall lung cellular senescence after 4-h of CIT in our study. Co-immunolabelling revealed the endothelial cells to be most affected by cold ischemia, demonstrating significant decrease in the endothelial cell senescence immediately after harvest. Annexin V-PI staining further revealed a prominent increase in the number of necrotic cells at 4-h CIT, thus suggesting that most of the cells undergo cell death within a few hours of cold ischemic injury. Conclusions: We thus concluded that CIT significantly lowers the cellular senescence in lung tissues and must be considered as a confounding factor for mechanistic studies in the future.

Ice-cold storage or controlled hypothermia to preserve marginal grafts in high-risk heart transplantation.

To evaluate the effectiveness of the Paragonix SherpaPak cardiac transport system (PSP) compared to the standard ice-cold storage (ICS) in extended-criteria donor grafts implanted in high-risk recipients. Data of all HTx at the University Centers of Udine and Bologna, between January 2020 and December 2023, employing extended-criteria donors in high-risk HTx conditions were retrospectively analyzed. Patient outcomes and complications after HTx were assessed. Endomyocardial biopsies were performed in donor hearts immediately after retrieval (T0), before implantation (T1) and at reperfusion (T2) to evaluate signs of myocardial damage. Overall, 90 patients who had heart transplantation (HTx) with a donor graft preserved with either ICS (n = 60) or PSP (n = 30) were included in the study. The 30-day mortality was 3% in both groups (p = 0.99), and 1-year survival 90% and 88% (p = 0.89) for recipients transplanted with PSP and ICS preserved grafts. Rates of moderate-to-severe graft dysfunction and bradi-arrhythmias for PSP and ICS groups were 7% versus 20% (p = 0.08), and 3% versus 15% (p = 0.09). Histologically, severe degrees of cellular and endothelial damage were absent in all PSP grafts while severe degree of contraction bands were higher in ICS hearts at T2. In high-risk donor-recipient matching, donor heart preservation with PSP seems to show a tendency toward better graft protection.

Update on the immunological mechanisms of primary graft dysfunction and chronic lung allograft dysfunction.

Primary graft dysfunction (PGD) and chronic lung allograft dysfunction (CLAD) are the leading causes of graft loss in lung transplant recipients. The development of mouse lung transplant models has allowed for the genetic dissection of cellular and molecular pathways that prevent graft survival. This review provides an overview into recent mechanistic insights into PGD and CLAD. Mouse orthotopic lung transplant models and investigations of human lung transplant recipeints have revealed new molecular and cellular targets that promote PGD and CLAD. Donor and recipient-derived innate immune cells promote PGD and CLAD. PGD is driven by communication between classical monocytes and tissue-resident nonclassical monocytes activating alveolar macrophages to release chemokines that recruit neutrophils. Products of cell damage trigger neutrophil NET release, which together with NK cells, antibodies and complement, that further promote PGD. The development of CLAD involves circuits that activate B cells, CD8+ T cells, classical monocytes, and eosinophils. Effective targeted management of PGD and CLAD in lung transplant recipient to improve their long-term outcome remains a critical unmet need. Current mechanistic studies and therapeutic studies in mouse models and humans identify new possibilities for prevention and treatment.

Comparing Different Methods for the Diagnosis of Liver Steatosis: What Are the Best Diagnostic Tools?

Due to the ongoing organ shortage, marginal grafts with steatosis are more frequently used in liver transplantation, leading to higher occurrences of graft dysfunction. A histological analysis is the gold standard for the quantification of liver steatosis (LS), but has its drawbacks: it is an invasive method that varies from one pathologist to another and is not available in every hospital at the time of organ procurement. This study aimed to compare non-invasive diagnostic tools to a histological analysis for the quantification of liver steatosis. Male C57BL6J mice were fed with a methioninecholine-deficient (MCD) diet for 14 days or 28 days to induce LS, and were compared to a control group of animals fed with a normal diet. The following non-invasive techniques were performed and compared to the histological quantification of liver steatosis: magnetic resonance spectroscopy (MRS), CARS microscopy, 99mTc MIBI SPECT imaging, and a new near-infrared spectrometer (NIR-SG1). After 28 days on the MCD diet, an evaluation of LS showed ≥30% macrovesicular steatosis. High correlations were found between the NIR-SG1 and the blinded pathologist analysis (R2 = 0.945) (p = 0.001), and between the CARS microscopy (R2 = 0.801 (p < 0.001); MRS, R2 = 0.898 (p < 0.001)) and the blinded pathologist analysis. The ROC curve analysis showed that the area under the curve (AUC) was 1 for both the NIR-SG1 and MRS (p = 0.021 and p < 0.001, respectively), while the AUC = 0.910 for the Oil Red O stain (p < 0.001) and the AUC = 0.865 for the CARS microscopy (p < 0.001). The AUC for the 99mTc MIBI SPECT was 0.640 (p = 0.013), and this was a less discriminating technique for LS quantification. The best-performing non-invasive methods for LS quantification are MRS, CARS microscopy, and the NIR-SG1. The NIR-SG1 is particularly appropriate for clinical practice and needs to be validated by clinical studies on liver grafts.

Risk of cellular or antibody-mediated rejection in pediatric kidney transplant recipients with BK polyomavirus replication-an international CERTAIN registry study.

In kidney transplant recipients (KTR), BK polyomavirus-associated nephropathy (BKPyVAN) is a major cause of graft loss. To facilitate the clearance of BKPyV-DNAemia, reduction of immunosuppression is currently the treatment of choice but may increase the risk of graft rejection. This international CERTAIN study was designed to determine the risk of alloimmune response and graft dysfunction associated with immunosuppression reduction for BKPyV treatment in 195 pediatric KTR. BKPyV-DNAemia was associated with a more than twofold increased risk of late T cell-mediated rejection (TCMR) (HR 2.22, p = 0.024), of de novo donor-specific HLA antibodies (dnDSA) and/or antibody-mediated rejection (ABMR) (HR 2.64, p = 0.002), and of graft function deterioration (HR 2.73, p = 0.001). Additional independent risk factors for dnDSA/ABMR development were a higher HLA mismatch (HR 2.72, p = 0.006) and re-transplantation (HR 6.40, p = 0.000). Other independent predictors of graft function deterioration were TCMR (HR 3.98, p = 0.003), higher donor age (HR 1.03, p = 0.020), and re-transplantation (HR 3.56, p = 0.013). These data indicate that reduction of immunosuppression for BKPyV-DNAemia management is associated with increased alloimmune response in pediatric KTR. Therefore, regular dnDSA screening and close monitoring of graft function in case of BKPyV-DNAemia followed by subsequent reduction of immunosuppressive therapy are recommended.

High-dimensional analysis of NK cells in kidney transplantation uncovers subsets associated with antibody-independent graft dysfunction.

Natural Killer (NK) cells respond to diseased and allogeneic cells through NKG2A/HLA-E or Killer-cell Immunoglobulin-like receptor (KIR)/HLA-ABC interactions. Correlations between HLA/KIR disparities and kidney transplant pathology suggest an antibody-independent pathogenic role for NK cells in transplantation, but mechanisms remain unclear. Using CyTOF to characterize recipient peripheral NK cell phenotypes and function, we observed diverse NK cell subsets amongst participants that responded heterogeneously to allo-stimulators. NKG2A+/KIR+ NK cells responded more vigorously than other subsets, and this heightened response persisted post-kidney-transplant despite immunosuppression. In test and validation sets from two clinical trials, pre-transplant donor-induced release of cytotoxicity mediator, Ksp37, by NKG2A+ NK cells correlated with reduced long-term allograft function. Separate analyses showed Ksp37 gene expression in allograft biopsies lacking histological rejection correlated with death censored graft loss. Our findings support an antibody-independent role for NK cells in transplant injury and support further testing of pre-transplant, donor-reactive, NK cell-produced Ksp37 as a risk-assessing, transplantation biomarker.

The Rapidly Evolving Landscape of DCD Heart Transplantation.

To summarise current international clinical outcomes from donation after circulatory death heart transplantation (DCD-HT); discuss procurement strategies, their impact on outcomes and overall organ procurement; and identify novel approaches and future areas for research in DCD-HT. Globally, DCD-HT survival outcomes (regardless of procurement strategy) are comparable to heart transplantation from brain dead donors (BDD). Experience with normothermic machine perfusion sees improvement in rates of primary graft dysfunction. Techniques have evolved to reduce cold ischaemic exposure to directly procured DCD hearts, though controlled periods of cold ischaemia can likely be tolerated. There is interest in hypothermic machine perfusion (HMP) for directly procured DCD hearts, with promising early results. Survival outcomes are firmly established to be equivalent between BDD and DCD-HT. Procurement strategy (direct procurement vs. regional perfusion) remains a source of debate. Methods to improve allograft warm ischaemic tolerance are of interest and will be key to the uptake of HMP for directly procured DCD hearts.

Donor age over 55 is associated with worse outcome in lung transplant recipients with idiopathic pulmonary fibrosis

BackgroundLung transplantation (LTx) remains the only efficient treatment for selected patients with end-stage pulmonary disease. The age limit for the acceptance of donor organs in LTx is still a matter of debate. We here analyze the impact of donor organ age and the underlying pulmonary disease on short- and long-term outcome and survival after LTx.MethodsDonor and recipient characteristics of LTx recipients at our institution between 03/2003 and 12/2021 were analyzed. Statistical analysis was performed using SPSS and GraphPad software.ResultsIn 230 patients analyzed, donor age ≥ 55 years was associated with a higher incidence of severe primary graft dysfunction (PGD2/3) (46% vs. 31%, p = 0.03) and reduced long-term survival after LTx (1-, 5- and 10-year survival: 75%, 54%, 37% vs. 84%, 76%, 69%, p = 0.006). Notably, this was only significant in recipients with idiopathic pulmonary fibrosis (IPF) (PGD: 65%, vs. 37%, p = 0.016; 1-, 5-, and 10-year survival: 62%, 38%, 16% vs. 80%, 76%, 70%, p = 0.0002 respectively). In patients with chronic obstructive pulmonary disease (COPD), donor age had no impact on the incidence of PGD2/3 or survival (21% vs. 27%, p = 0.60 and 68% vs. 72%; p = 0.90 respectively). Moreover, we found higher Torque-teno virus (TTV)-DNA levels after LTx in patients with IPF compared to COPD (X2 = 4.57, p = 0.033). Donor age ≥ 55 is an independent risk factor for reduced survival in the whole cohort and patients with IPF specifically.ConclusionsIn recipients with IPF, donor organ age ≥ 55 years was associated with a higher incidence of PGD2/3 and reduced survival after LTx. The underlying pulmonary disease may thus be a relevant factor for postoperative graft function and survival.Trial registration number DKRSDRKS00033312.

Defining the Etiology of Renal Allograft Dysfunction Using Banff 2019 Classification: Correlation with Post-Transplant Duration and Creatinine Levels-A Comprehensive Analysis of 200 Renal Biopsies at a Tertiary Care Medical Center Hospital.

Chronic kidney disease is a growing global health issue, contributing significantly to morbidity and mortality. The incidence of end-stage renal disease (ESRD) is approximately 100 per million population. Renal transplantation remains the cornerstone treatment for ESRD, with a projected 20-year survival rate of 60%. We aim to define the etiology of renal allograft dysfunction using the Banff 2019 classification by analyzing 200 renal allograft biopsies in correlation with creatinine levels across post-transplant time frames. 200 renal allograft biopsies are analyzed using the recent Banff 2019 classification with creatinine levels and post-transplant duration correlation. The study included 150 (75%) male patients and 50 (25%) female patients, with the majority 78 (39%) representing the age group of 16-30 years. 36 (18%) biopsies were within 3-month post-transplant, while 92 (46%) were 2-year post-transplant. According to the Banff 2019 classification, 92 (46.0%) transplant rejection biopsies were identified, with most 54 (27%) exhibiting antibody-mediated rejection (Category 2), including 40 (20%) active acute antibody-mediated rejection (ABMR) and 14 (7.0%) chronic active ABMR. T-cell-mediated rejection (TCMR; Category 4) represented 12 (6%) biopsies, including 10 (5%) acute TCMR and 2 (1%) chronic active TCMR. Category 5, the miscellaneous group, represented 100 (50%) biopsies, out of which 32 (16%) exhibited calcineurin inhibitor (CNI) toxicity, 38 (19%) acute tubular necrosis, and 8 (4%) thrombotic microangiopathy. A notable variation in the dysfunction distribution across different post-transplant time frames indicated a temporal evolution in the underlying causes of allograft dysfunction. Specific Banff categories showed a robust association with renal dysfunction, potentially contributing to the elevation of creatinine levels and renal function deterioration. Our study highlights the intricate pathophysiology of renal allograft dysfunction. Most biopsies were attributed to ABMR whereas one-third of biopsies exhibited mixed lesions (ABMR and TCMR or ABMR and calcineurin inhibitor toxicity (CNIT)). Additionally, this study suggests that renal allograft rejection remains a significant contributor to graft dysfunction. A complex interplay between histological findings, Banff classification, and renal function is noted. A significant difference in the distribution of dysfunction across post-transplant time frames is noted suggesting a temporal evolution in the etiology of allograft dysfunction. Certain Banff categories demonstrate a stronger association with renal dysfunction that may influence creatinine level increase and renal function deterioration. In correspondence to the recent Banff 2019 guidelines for diagnosing ABMR, we emphasize the role of C4d staining on immunofluorescence or immunohistochemistry in allograft biopsies as imperative for timely diagnosis and immunosuppressant therapy adjustment, ultimately enhancing graft survival. Further research is needed to elucidate the underlying mechanisms driving renal dysfunction in different Banff categories, ultimately informing personalized management strategies for patients with renal allograft dysfunction. In line with the Banff 2019 guidelines for diagnosing ABMR, this study highlights the critical role of C4d staining through immunofluorescence or immunohistochemistry in allograft biopsies for early diagnosis and timely adjustment of immunosuppressive therapy, ultimately improving graft survival.

Value of Factor V in the diagnosis of early graft dysfunction after liver transplantation: Internal validation.

Primary graft dysfunction is a major early complication following liver transplantation, potentially leading to retransplantation or patient death. Coagulation Factor V (FV) and ALT have emerged as important biomarkers in assessing liver function, yet their role as early predictors of graft loss has not been fully validated. The aim of this study is to conduct an internal validation of published results on the applicability of FV and ALT for diagnosing graft dysfunction and its predictive ability for graft loss within the first 90 days. We conducted a retrospective cohort study including 513 adult recipients from 2012 to 2023 at the Regional University Hospital of Málaga. FV and ALT levels were measured on postoperative day 2, and patients were categorized based on FV <37.5 and ALT >1539. The association with 90-day graft loss was analyzed. Graft loss occurred in 43 patients (8.4%) within the first 90 days. The combination of FV <37.5 and ALT >1539 on postoperative day 2 demonstrated a specificity of 99% and a test efficiency of 94% in predicting graft loss. Patients meeting both criteria had a 74-fold increased risk of graft loss, with most losses occurring within the first week, and a median survival of 4 days. These findings suggest that FV and ALT on postoperative day 2 are reliable early markers for predicting graft loss, enabling risk stratification and guiding critical decisions regarding early retransplantation in the immediate postoperative period.

B-234 Evaluating the diagnostic utility of dd-cf-dna in renal allograft surveillance: a single-center perspective

Abstract Background Donor-derived cell-free DNA (dd-cf-DNA) tests offer a non-invasive alternative to biopsy for allograft surveillance in solid organ transplantation. Unlike biopsies, dd-cf-DNA tests are not subject to interpretation bias and have the potential to detect subclinical rejection, which can lead to graft dysfunction and poor outcomes. At our institution, dd-cf-DNA testing is currently offered as a send out test and we sought to evaluate its efficacy in monitoring our post-transplant patients. Methods We retrospectively examined electronic health records of 50 renal transplant patients with dd-cf-DNA (using AlloSure and Prospera assays) between January 1st, 2019, and December 31st, 2022 to assess diagnostic utility of dd-cf-DNA relative to donor-specific antibodies (DSA) and biopsy (all predictors of graft function). Statistical analysis included correlation testing with t-tests. Results Overall, dd-cf-DNA levels correlated with DSA levels (p = 0.0002) and patients with both HLA-class I and II DSA had significantly higher dd-cf-DNA levels (p&amp;lt; 0.05). The Prospera dd-cf-DNA assay appeared to be a better predictor of DSA levels (p = 0.04) than the Allosure dd-cf-DNA assay. Though not statistically significant, there was trend towards an increase in dd-cf-DNA in patient with biopsy-proven graft injury and rejection vs no rejection. Interestingly, dd-cf-DNA levels were significantly elevated in patients with biopsy-proven antibody mediated rejection (ABMR). Because dd-cfDNA levels have been reported to be impacted by sensitizing events including prior transplant, we evaluated and observed levels of dd-cf-DNA to be higher in patients with a history of more than one graft vs single graft recipients (p&amp;lt; 0.0001) and this observation was prominent in the Allosure assay. Conclusions Our findings suggest that dd-cf-DNA testing holds promise as a valuable tool for graft surveillance and early detection of ABMR. The lack of correlation with biopsy-confirmed rejections may be attributed to the dd-cf-DNA assays’ ability to detect rejection events earlier in the disease progression process compared to biopsy. Time course analysis will be beneficial. Additionally, the observed differences between AlloSure and Prospera emphasize the significance of thoroughly evaluating and selecting assays, particularly in multi-transplant recipients. We highlight that our initial analysis is limited due to a small sample size. However, we aim to assess 200 patients by the conclusion of this study.

Belatacept-related cytomegalovirus infection: Advocacy for tailored immunosuppression based on individual assessment of immune fitness

Belatacept, a fusion protein combining CTLA-4 and the Fc region of human IgG1, is increasingly used as a calcineurin inhibitor–sparing regimen in patients with chronic graft dysfunction. Older kidney transplant recipients, particularly from expanded criteria donors, may be switched to belatacept due to poor renal recovery. However, late-onset cytomegalovirus (CMV) reactivation is increasingly reported with this treatment, especially in older patients with graft dysfunction. This suggests a progressive loss of CMV-specific T cell response, potentially driven by T cell exhaustion. Contributing factors include preexisting T cell dysfunction, increased viral antigen exposure, and interference in the PD-L1/PD-1 pathway by belatacept. mTOR inhibitors have shown efficacy in preventing CMV reactivation by reinvigorating CMV-specific T cells. These findings support combining belatacept with mTOR inhibitors in high-risk CMV-seropositive recipients and emphasize the need for personalized immune assessments to guide immunosuppressive strategies.

Loss of Nr4a1 ameliorates endothelial cell injury and vascular leakage in lung transplantation from circulatory-death donor

BackgroundIschemia-reperfusion injury (IRI) stands as a major trigger for primary graft dysfunction (PGD) in lung transplantation (LTx). Especially in LTx from donation after cardiac death (DCD), effective control of IRI following warm ischemia (WIRI) is crucial to prevent PGD. This study aimed to identify the key factors affecting WIRI in LTx from DCD. MethodsPreviously reported RNA-sequencing dataset of lung WIRI was reanalyzed to identify nuclear receptor subfamily 4 group A member 1 (NR4A1) as the immediate early gene for WIRI. Dynamics of NR4A1 expression were verified using a mouse hilar clamp model. To investigate the role of NR4A1 in WIRI, a mouse model of LTx from DCD was established using Nr4a1 knockout (Nr4a1-/-) mice. ResultsNR4A1 was located around vascular cells, and its protein levels in the lungs increased rapidly and transiently during WIRI. LTｘ from Nr4a1-/- donors significantly improved pulmonary graft function compared to wild-type donors (P < 0.001). Histological analysis showed decreased microvascular endothelial cell death (P = 0.007), neutrophil infiltration (P < 0.001), and albumin leakage (P < 0.001). Evans blue permeability assay demonstrated maintained pulmonary microvascular barrier integrity in grafts from Nr4a1-/- donors, correlating with diminished pulmonary edema (P < 0.001). However, NR4A1 did not significantly affect the inflammatory response during WIRI, and IRI was not suppressed when a wild-type donor lung was transplanted into the Nr4a1-/- recipient. ConclusionsDonor NR4A1 plays a specialized role in the positive regulation of endothelial cell injury and microvascular hyperpermeability. These findings demonstrate the potential of targeting NR4A1 interventions to alleviate PGD and improve outcomes in LTx from DCD.

CytoSorb® hemoadsorption of apixaban during cardio-pulmonary bypass for heart transplantation

IntroductionHeart transplantation is an emergency surgery requiring cardio-pulmonary bypass (CPB) and its timing is unpredictable. Patients on the transplant waiting list often have multiple reasons for being anticoagulated. Direct oral anticoagulants (DOACs) such as apixaban are very popular due to their well-known advantages. Intraoperative removal of apixaban using CytoSorb® (CytoSorbents Inc., Princeton, NJ, USA), seems to be an interesting solution for patients on DOACs requiring an emergency CPB intervention. The aim of this short communication is to describe the perioperative effects of the use of the CytoSorb® hemoadsorption device during emergency CPB for a heart transplant patient Case presentationA 61-year-old male patient (75kg/173cm) wait-listed for heart transplantation was admitted to our hospital (Pitié-Salpêtrière Hospital, Sorbonne University, Paris, France) to benefit from a heart transplantation. This patient, with many comorbidities, has an end-stage heart failure with multiple episodes of decompensation over the previous year. He was anticoagulated with a Vitamin K antagonist (VKA) due to atrial fibrillation and was switched to apixaban (5mg twice daily) 9 days before surgery based on poor clotting control. A NaCl 0.9% primed CytoSorb cartridge was inserted into the CPB circuit. Hemoadsorption was performed during the entire CPB duration. Anti-Factor Xa Activity (AFXaA) levels were taken at multiple time points before, during and after surgery in order to monitor anticoagulation. Results. Preoperatively, activated Clotting Time (ACT) was 146 seconds. The ACT reached 545 seconds after administration of 25,000IU of unfractionated heparin (UFH). Surgery consisted of an orthotopic heart transplantation with bi-caval anastomoses.CPB duration was 133 minutes with 83 minutes of aortic cross clamping. Total graft ischemic time was 249 minutes. At the time of anesthesia induction and after UFH administration, AFXaA levels were 330ng/mL and 317ng/mL, respectively. Thereafter, AFXaA decreased to 137ng/mL during CPB and to 57ng/mL after the end of CPB and 250mg (=25,000IU) of protamine administration.After surgery, AFXaA levels stabilized over 50ng/mL over the next 14 hours. Postoperative anticoagulation was performed with the use of UFH starting 6 hours after surgery.No primary graft dysfunction (PGD) was observed, and during the post-operative period of 72 hours, the patient did not have any bleeding events requiring reintervention or transfusion. ConclusionIn conclusion, we observed that CytoSorb® could be a potential solution to remove apixaban intraoperatively. If this efficacy is confirmed in larger trials, it would allow transplant candidates to be treated with DOACs without requiring a switch to VKAs.