Transplantation最新文献

Background: Long-term renal allograft acceptance has been achieved in macaques using a transient mixed hematopoetic chimerism protocol, but similar regimens have proven unsuccessful in heart allograft recipients unless a kidney transplant was performed simultaneously. Here, we test whether a modified protocol based on targeting CD154, CD2, and CD28 is sufficient to prolong heart allograft acceptance or promote the expansion of regulatory T cells.

Methods: Eight macaques underwent heterotopic allo-heart transplantation from major histocompatibility complex-mismatched donors. Induction treatment for donor bone marrow transplantation (BMT) was administered after a 4-mo delay period under TNX-1500 monotherapy. The BMT induction regimen comprised 1 (group 1, G1; n = 3) or 2 (group 2, G2; n = 5) doses of total body irradiation, thymic irradiation, and antithymocyte globulin, followed by 2 (G1) or 5 (G2) weekly doses of αCD2 and 5 weekly treatments with αCD28 and TNX-1500.

Results: During the delay period, 1 G1 graft was rejected and 2 (1 in each group) exhibited moderate rejection on protocol biopsy before BMT. Lymphocyte chimerism was seen in 3 of 5 G2 animals and in 1 of 2 G1 recipients. One G1 graft was rejected despite chimerism, whereas the other recipient succumbed to anti-cytomegalovirus treatment. Two G2 monkeys succumbed due to infection (cytomegalovirus, bacteremia) post-BMT and 3 due to posttransplantation lymphoproliferative disease.

Conclusions: Intensive costimulation pathway blockade with αCD2, αCD154, and αCD28 promotes lymphocyte chimerism at the cost of high incidence of posttransplantation lymphoproliferative disease and opportunistic infections, preventing assessment of the effectiveness of the regimen to promote alloimmune tolerance.

Tissue-resident lymphocytes (TRLs) provide a front-line immunological defense mechanism uniquely placed to detect perturbations in tissue homeostasis. The heterogeneous TRL population spans the innate to adaptive immune continuum, with roles during normal physiology in homeostatic maintenance, tissue repair, pathogen detection, and rapid mounting of immune responses. TRLs are especially enriched in the liver, with every TRL subset represented, including liver-resident natural killer cells; tissue-resident memory B cells; conventional tissue-resident memory CD8, CD4, and regulatory T cells; and unconventional gamma-delta, natural killer, and mucosal-associated invariant T cells. The importance of donor- and recipient-derived TRLs after transplantation is becoming increasingly recognized, although it has not been examined in detail after liver transplantation. This review summarizes the evidence for the roles of TRLs in liver transplant immunology, focusing on their features, functions, and potential for their harnessing to improve transplant outcomes.

Background: Initial analysis of liver transplant biopsies in the INTERLIVER study (ClinicalTrials.gov; unique identifier NCT03193151) using rejection-associated transcripts failed to find an antibody-mediated rejection state (ie, rich in natural killer [NK] cells and with interferon-gamma effects). We recently developed an optimization strategy in lung transplants that isolated an NK cell-enriched rejection-like (NKRL) state that was molecularly distinct from T cell-mediated rejection (TCMR). Here we apply the same strategy to a liver transplant biopsy population.

Methods: We used this strategy to search for a molecular NKRL state in 765 consented liver transplant biopsies collected at participating international centers for gold-standard histology and molecular assessment by genome-wide microarrays. Validation through a training set-test set approach of an optimized selection of variables as inputs into unsupervised rejection classification identified an NKRL state in livers.

Results: The full model classified 765 biopsies into the following molecular phenotypes, characterized by their gene expression: no-rejection 54%, TCMR 16%, NKRL 13%, and injury 16%. Top TCMR transcripts were expressed in effector T cells; top NKRL transcripts were almost exclusively expressed in NK cells; and both had increased interferon-γ-inducible transcripts, which were more pronounced in TCMR. Most TCMR biopsies had significant parenchymal injury, molecular fibrosis, and abnormal biochemistry. NKRL biopsies had no excess of injury, fibrosis, or biochemistry abnormalities.

Conclusions: Optimized rejection algorithms indicate that some liver transplants manifest an NKRL state that is well tolerated in the short term postbiopsy and with minimal injury and relatively normal biochemistry, while also underscoring the potential of TCMR to produce extensive parenchymal injury.

Chronic rejection is arguably the main obstacle to long-term graft survival. Yet, clinical trials focusing on this condition are disappointingly scarce. Significant advances in treating chronic rejection cannot happen if there is no conduit for testing novel therapies. Here, we identified the main hurdles holding back clinical trials for chronic rejection and outlined a series of actions to address these roadblocks. We suggest that a new strategic plan combining expertise in basic and clinical research and leveraging complementary resources be launched to specifically target chronic rejection and achieve long-awaited progress. We only need the will.

Background: Induced pluripotent stem cells (iPSCs) offer the potential to generate autologous iPSC-derived islets (iPSC islets), however, remain limited by scalability and product safety.

Methods: Herein, we report stagewise characterization of cells generated following a bioreactor-based differentiation protocol. Cell characteristics were assessed using flow cytometry, quantitative reverse transcription polymerase chain reaction, patch clamping, functional assessment, and in vivo functional and immunohistochemistry evaluation. Protocol yield and costs are assessed to determine scalability.

Results: Differentiation was capable of generating 90.4% PDX1 + /NKX6.1 + pancreatic progenitors and 100% C-peptide + /NKX6.1 + iPSC islet cells. However, 82.1%, 49.6%, and 0.9% of the cells expressed SOX9 (duct), SLC18A1 (enterochromaffin cells), and CDX2 (gut cells), respectively. Explanted grafts contained mature monohormonal islet-like cells, however, CK19 + ductal tissues persist. Using this protocol, semi-planar differentiation using 150 mm plates achieved 5.72 × 10 4 cells/cm 2 (total 8.3 × 10 6 cells), whereas complete suspension differentiation within 100 mL Vertical-Wheel bioreactors significantly increased cell yield to 1.1 × 10 6 cells/mL (total 105.0 × 10 6 cells), reducing costs by 88.8%.

Conclusions: This study offers a scalable suspension-based approach for iPSC islet differentiation within Vertical-Wheel bioreactors with thorough characterization of the ensuing product to enable future protocol comparison and evaluation of approaches for off-target cell elimination. Results suggest that bioreactor-based suspension differentiation protocols may facilitate scalability and clinical implementation of iPSC islet therapies.

Trafficking in human organs, cells, and tissues has long been a source of concern for health authorities and professionals, and several international ethical guidance documents and national laws have affirmed the prohibition of trade in these substances of human origin (SoHOs). However, despite considerable attention to the issue of organ trafficking, this remains a substantial and widespread problem internationally. In contrast, trafficking in cells, tissues, and medical products derived from SoHOs has received comparatively little attention, and the extent and nature of such trafficking remain largely unknown. Consequently, as part of the 2023 Global Summit on Convergence in Transplantation held in Santander, Spain, an ethics working group was assigned the task of formulating actionable recommendations to support the prevention of trafficking in all SoHOs. In reporting on this work, we review factors that may influence the persistent trafficking of SoHOs, explore the potential difficulties associated with the collection and reporting of data about suspected trafficking activities, and argue that more practical and consistent guidance, training, and regulatory frameworks are needed internationally to support effective reporting, sharing of data, and collaborative responses to suspected trafficking cases. We also discuss the importance of psychosocial evaluation of living donors as a strategy to detect and prevent organ trafficking and strive to advance the implementation of this well-established recommendation by outlining minimum standards for psychosocial evaluation of living donors.

Background: The clinical standard for pancreas preservation for transplantation is static cold storage (SCS). Oxygenation during preservation has been shown to be advantageous in clinical studies. This study evaluates the efficiency of different oxygenation modalities during hypothermic pancreas preservation.

Methods: Thirty-two porcine pancreases were procured in a controlled donation after circulatory death model and were divided to be preserved in 8 groups: (1) SCS, (2) hypothermic machine perfusion (HMP), (3) hypothermic oxygenated machine perfusion (HOPE) with 21% oxygen, (4) HOPE and 100%, (5) SCS and oxygen carrier, M101, (6) HMP and M101, (7) HOPE 21% and M101, and (8) HOPE 100% and M101. All the groups underwent 24 h of hypothermic preservation, followed by 2 h of normothermic reperfusion. Oxygen partial pressures were assessed using parenchymal probes. Perfusion parameters, perfusate samples, and tissue biopsies were analyzed.

Results: This study showed that HMP was linked to higher tissue oxygen partial pressures, lower succinate levels, and better reperfusion parameters. Furthermore, the addition of M101 to either SCS or HMP was associated with lower succinate and creatinine phosphokinase accumulation, suggesting a protective effect against ischemia.

Conclusions: Our research has demonstrated the efficacy of machine perfusion in hypothermic conditions in providing oxygen to the pancreas during preservation and conditioning the pancreatic microvasculature for reperfusion during transplantation. Furthermore, the addition of M101 suggests a protective effect on the graft from ischemia.

Background: Living-donor liver transplantation has been widely performed as an alternative to the scarce liver grafts from deceased donors. More studies are reporting favorable outcomes of left liver graft (LLG). This study compared the clinical outcomes between living-donor liver transplantation using LLG and right liver graft (RLG) with similar graft-to-recipient body weight ratios.

Methods: This study analyzed 4601 patients from a multicenter observational cohort using the Korean Organ Transplantation Registry between 2014 and 2021. After matching the Model for End-stage Liver Disease score and graft-to-recipient body weight ratios because of the extremely different number in each group, the LLG and RLG groups comprised 142 (25.1%) and 423 (74.9%) patients, respectively.

Results: For donors, the median age was higher in the LLG group than in the RLG group (34 y [range, 16-62 y] versus 30 y [16-66 y] ; P  = 0.002). For recipients, the LLG group showed higher 90-d mortality than the RLG group (11 [7.7%] versus 9 [2.1%]; P  = 0.004). The long-term graft survival was significantly worse in the LLG group ( P  = 0.011). In multivariate Cox proportional hazards regression analysis for graft survival, LLG was not a significant risk factor (hazard ratio, 1.01 [0.54-1.87]; P  = 0.980). Otherwise, donor age (≥40 y; 2.18 y [1.35-3.52 y]; P  = 0.001) and recipients' body mass index (<18.5 kg/m 2 ; 2.98 kg/m 2 [1.52-5.84 kg/m 2 ]; P  = 0.002) were independent risk factors for graft survival.

Conclusions: Although the short-term and long-term graft survival was worse in the LLG group, LLG was not an independent risk factor for graft survival in multivariate analysis. LLGs are still worth considering for selected donors and recipients regarding risk factors for graft survival.

Background: Descriptions of eosinophils in transbronchial biopsy (TBBx) pathology reports after lung transplantation (LTx) are associated with poor long-term outcomes. The absence of routine reporting and standardization precludes accurate assessment of this histologic predictor. A systematic reporting scheme for the presence of TBBx eosinophils after LTx was implemented. This report aims to assess this scheme by describing the presence, pattern, and gradation of TBBx eosinophils and clinical associations.

Methods: A prospective cross-sectional study of all TBBx reports was performed including all patients presenting for a surveillance or diagnostic TBBx between January 2020 and June 2023. Each TBBx was systematically reported in a blinded manner. Mixed-effects logistic regression was performed to measure the association between concurrent clinical and histologic features, and the presence of TBBx eosinophils.

Results: A total of 410 TBBx reports from 201 patients were systematically reported. In 43.8% recipients, any TBBx eosinophils were detected and in 17.1% recipients, higher-grade eosinophils (≥3 per high power field) were present. Adjusted analysis showed that retransplantation, A- and B-grade cellular rejection, positive bronchoalveolar lavage (BAL) bacterial microbiology, and elevated blood eosinophil count were independently associated with the presence of any TBBx eosinophils. Diagnostic "for-cause" procedures were independently associated with higher quantities of TBBx eosinophils.

Conclusions: Systematic reporting demonstrates that TBBx eosinophils are a distinct inflammatory response associated with rejection, infection, and peripheral eosinophilia. Although these findings require multicenter external validation, standardized reporting for TBBx eosinophils may assist in identifying recipients at risk of poor outcomes and provides a platform for mechanistic research into their role after lung transplantation.