Donor Cells Research Articles

Hemoglobin Electrophoresis versus Kleihauer Betke to Determine Bone Marrow Suppression in Fetuses Undergoing Intrauterine Transfusion.

Mainstay therapy for fetuses affected by maternal red cell alloimmunization is serial IUT (intrauterine transfusion). Testing to determine when fetal red cells have been replaced with donor cells historically involves the use of the KB (Kleihauer-Betke) test. Hgb (Hemoglobin) electrophoresis testing may be more rapid with a reduced cost of analysis. We aimed to determine the correlation between fetal Hgb electrophoresis versus the traditional KB test. This is a retrospective analysis on all alloimmunized singleton pregnancies undergoing IUT between 1/1/2021 and 7/1/2023. Maternal and fetal characteristics were collected along with indication for IUT. A final fetal blood sample was obtained at the conclusion of each transfusion and sent for KB testing and Hgb electrophoresis. The primary outcome was the assessment of these parameters in their ability to predict replacement of the fetal circulating red cell population with donor cells. Linear regression analysis and repeated measures analysis of variance were performed, P values less than 0.05 were considered significant. A total of 56 IUTs were performed in 16 patients. There were 39 (69.6%) final KB test values collected and compared to 30 (53.6%) final Hgb electrophoresis values. Hgb electrophoresis when compared to the KB test demonstrated a significant correlation (R2 = 0.93; 95% confidence interval, 0.61-0.76; P <0.001). This same finding held true when examining correlation at each individual IUT as well. The final KB test and Hgb electrophoresis value significantly decreased with each transfusion (P=0.003). A predominance of adult donor blood was noted by the third transfusion for both laboratory indices. Fetal Hgb electrophoresis obtained at the time of IUT demonstrates a significant correlation with the traditional KB test.

Persistent Antigen A after Minor ABO-Incompatible Hematopoietic Stem Cell Transplantation in Children: Two Case Reports

&lt;b&gt;&lt;i&gt;Introduction:&lt;/i&gt;&lt;/b&gt; ABO blood type changes after ABO-incompatible hematopoietic stem cell transplantation (HSCT). Most non-hematopoietic tissues retain the expression of the patient’s own ABO antigens, which may adsorb from the plasma onto the donor’s red blood cells (RBCs). Because of this phenomenon, a persistent patient’s A and/or B antigen could be detected in the laboratory, despite 100% white cell donor chimerism. Adsorption of the patient’s soluble ABO antigens on the newly formed RBCs complicates the interpretation of the patient’s blood type and decision of transfusion therapy. &lt;b&gt;&lt;i&gt;Case Presentation:&lt;/i&gt;&lt;/b&gt; The first case report is a 6-year-old girl, A, D+, with T-cell acute lymphoblastic leukemia (ALL), transplanted with HLA-matched unrelated group O, D+ bone marrow. A second case report describes an 8-year-old girl, AB, D−, with ALL transplanted with an HLA-matched related group B, D+ bone marrow. The presence of persistent antigen A was registered in both patients more than 1 year after HSCT, despite complete donor chimerism. &lt;b&gt;&lt;i&gt;Conclusion:&lt;/i&gt;&lt;/b&gt; The weak expression of ABO antigens on RBCs after HSCT should be examined in detail for proper planning of transfusion therapies.

Application of exosomes in oral regenerative medicine

In recent years, exosomes had been recognized as a potential cell-free therapeutic tool in the field of regenerative medicine due to their easy accessibility, low immunogenicity, and good therapeutic effect. As paracrine products of cells, exosomes not only have the functions of their donor cells but also involve fewer ethical disputes. They are more stable than traditional stem cell therapy, and easy to store, transport and sterilize, which are gradually applied in the field of oral regenerative medicine. This article provides a review of the general properties of exosomes and their application in the field of oral regeneration, with a view to exploring new pathways for functional regeneration of the stomatognathic system.

#2639 Unraveling complement activation profiles on endothelial cells in healthy donors using an ex vivo model

Abstract Background and Aims Complement is involved in numerous kidney diseases. However, functional approaches to properly examine individual's susceptibility to complement dysregulation are limited. Method We assessed ex vivo complement activation induced by sera from 38 healthy donors on resting microvascular endothelial cells (HMEC-1) with or without complement dysregulation by an anti-FH monoclonal antibody (OX-24 mAb). Following incubation, immunofluorescence was used to reveal and quantify membrane-bound C3c (evaluating C3b/iC3b) and C5b-9 with a computer-assisted method (H-score). Additionally, complement anaphylatoxins (C3a and C5a) were quantified in cell supernatants by ELISA. Further exploration of ex vivo complement activation profiles were conducted by next generation sequencing of a panel of alternative pathway genes in 32 donors. Results Increase in complement deposition on HMEC-1 surface was defined for a H-scoreC3c &amp;gt; 50 and/or a H-scoreC5b-9 &amp;gt; 30. Combined analysis of C3b/iC3b and C5b-9 deposition in 35 donors showed that one donor (2.8%) had an isolated increase in C3b/iC3b deposits, 3 (8.6%) had an isolated increase in C5b-9 deposits and one other (2.8%) had both increased C3b/iC3b and C5b-9 deposition. Genetic analysis of 32/38 donors revealed 3 heterozygous rare or low frequency missense variants in CFH (p.N1050Y and p.R1210C) and CFI (p.A76G) in 3/5 donors (60%) with increased complement deposition. Conclusion Our ex vivo model for measuring complement activation allowed the identification of distinct complement activation profiles among healthy donors, revealing genetic susceptibility in 3 donors. This new dynamic and functional model provides an exciting avenue for exploring the mechanisms governing complement dysregulation in various kidney diseases in research.

Posttransplant cyclophosphamide versus anti-thymocyte globulin versus combination for graft-versus-host disease prevention in haploidentical transplantation for adult acute myeloid leukemia: A report from the European Society for Blood and Marrow Transplantation Acute Leukemia Working Party.

The optimal choice for graft-versus-host disease (GVHD) prophylaxis in haploidentical stem cell transplantation (haplo-SCT) remains debatable. Posttransplant cyclophosphamide (PTCy) and anti-thymocyte globulin (ATG) are two common strategies, but little is known about their combination. Using the European Society for Blood and Marrow Transplantation (EBMT) registry, the authors identified 3649 adult patients with acute myeloid leukemia (AML) who underwent haplo-SCT in complete remission between 2007 and 2021 at 260 EBMT-participating centers who received either PTCy (n=2999), ATG (n=358), or combination prophylaxis (n=292). Cord blood transplants, combined bone marrow and peripheral grafts, and transplants with ex vivo graft manipulation were excluded. Median follow-up was 31.8 months. On multivariate analysis, adjusting for patient age and performance status, disease status at transplant, cytogenetic risk, conditioning intensity, stem cell source, female-to-male graft, and donor and patient CMV status, we present the following. Compared to PTCy, ATG had a higher risk of nonrelapse mortality (hazard ratio [HR], 1.6; p=.003), worse leukemia-free survival (HR, 1.4; p=.002), overall survival (HR,1.49; p=.0009), and GVHD-free and relapse-free survival (HR,1.29; p=.012). The combination of PTCy and ATG, however, led to significantly reduced rates of grade 2-4 (HR, 0.51; p=.0003) and grade 3-4 (HR, 0.5; p=.018) acute GVHD and did not affect any transplant outcomes compared to PTCy without ATG. The authors conclude that ATG alone is a less effective prophylaxis strategy compared to PTCy, however, the combination of PTCy and ATG is superior to either monotherapy. They propose that this combination could be considered a potential new standard of care for GVHD prophylaxis in haplo-SCT for AML.

Hemangiosarcoma Cells Promote Conserved Host-Derived Hematopoietic Expansion.

Hemangiosarcoma and angiosarcoma are soft-tissue sarcomas of blood vessel-forming cells in dogs and humans, respectively. These vasoformative sarcomas are aggressive and highly metastatic, with disorganized, irregular blood-filled vascular spaces. Our objective was to define molecular programs which support the niche that enables progression of canine hemangiosarcoma and human angiosarcoma. Dog-in-mouse hemangiosarcoma xenografts recapitulated the vasoformative and highly angiogenic morphology and molecular characteristics of primary tumors. Blood vessels in the tumors were complex and disorganized, and they were lined by both donor and host cells. In a series of xenografts, we observed that the transplanted hemangiosarcoma cells created exuberant myeloid hyperplasia and gave rise to lymphoproliferative tumors of mouse origin. Our functional analyses indicate that hemangiosarcoma cells generate a microenvironment that supports expansion and differentiation of hematopoietic progenitor populations. Furthermore, gene expression profiling data revealed hemangiosarcoma cells expressed a repertoire of hematopoietic cytokines capable of regulating the surrounding stromal cells. We conclude that canine hemangiosarcomas, and possibly human angiosarcomas, maintain molecular properties that provide hematopoietic support and facilitate stromal reactions, suggesting their potential involvement in promoting the growth of hematopoietic tumors.

Hybrid cord blood banking in a private-public-partnership: Women's perspectives.

The increasing demand for umbilical cord blood (UCB) used in stem cell transplantation led to the establishment of cord blood (CB) banks worldwide. These include public foreign donor banks and private family-directed donor banks. Recently, our department has introduced a third banking model within a private-public-partnership. This hybrid banking allows for storage of family-directed CB units, while also getting Human leukocyte antigen (HLA)-typed and included in the national stem cell donor registry. So if the need arises, the HLA-compatible CB unit can be released to an unrelated recipient as a foreign donor stem cell graft. The aim of this study was to evaluate women's perspectives on the different CB banking options as well as retrospective satisfaction with their decisions. We performed a prospective survey study in postpartum women, using a validated questionnaire. A total of 157 women were included in this survey study; 68% of them decided to have their UCB stored or donated. Among those women, 25% of them opted for hybrid storage, 72% of respondents stored UCB publicly, and 3% decided for private family-directed storage. Our study shows the potential of hybrid banking as an attractive UCB storage option, as an alternative to family-directed banking rather than a substitute for public donation. Hybrid storage potentially combines advantages of family-directed banking as well as unrelated CB donation expanding the number of registered CB units available for transplantation and giving every pregnant woman the possibility to store UCB.

A case of acute lung injury in a peripheral blood stem cell donor mobilized with pegylated recombinant human granulocyte colony-stimulating factor.

Pegylated recombinant human granulocyte colony-stimulating factor (PEG-rhG-CSF) has been introduced for the mobilization of peripheral blood stem cells (PBSCs). However, no cases of acute lung injury (ALI) in healthy donors have been reported, and the underlying mechanisms remain poorly understood. We first reported a case of ALI caused by PEG-rhG-CSF in a healthy Chinese donor, characterized by hemoptysis, hypoxemia, and patchy shadows. Ultimately, hormone administration, planned PBSC collection, leukocyte debridement, and planned PBSC collection resulted in active control of the donor's ALI. The donor's symptoms improved without any adverse effects, and the PBSC collection proceeded without incident. Over time, the lung lesion was gradually absorbed and eventually returned to normal. PEG-rhG-CSF may contribute to ALI in healthy donors via mechanisms involving neutrophil aggregation, adhesion, and the release of inflammatory mediators in the lung. This case report examines the clinical manifestations, treatment, and mechanism of lung injury induced by PEG-rhG-CSF-mobilized PBSCs.

DNA-Binding Proteins and Passenger Proteins in Plasma DNA-Protein Complexes: Imprint of Parental Cells or Key Mediators of Carcinogenesis Processes?

Knowledge of the composition of proteins that interact with plasma DNA will provide a better understanding of the homeostasis of circulating nucleic acids and the various modes of interaction with target cells, which may be useful in the development of gene targeted therapy approaches. The goal of the present study is to shed light on the composition and architecture of histone-containing nucleoprotein complexes (NPCs) from the blood plasma of healthy females (HFs) and breast cancer patients (BCPs) and to explore the relationship of proteins with crucial steps of tumor progression: epithelial-mesenchymal transition (EMT), cell proliferation, invasion, cell migration, stimulation of angiogenesis, and immune response. MALDI-TOF mass spectrometric analysis of NPCs isolated from blood samples using affine chromatography was performed. Bioinformatics analysis showed that the shares of DNA-binding proteins in the compositions of NPCs in normal and cancer patients are comparable and amount to 40% and 33%, respectively; in total, we identified 38 types of DNA-binding motifs. Functional enrichment analysis using FunRich 3.13 showed that, in BCP blood, the share of DNA-binding proteins involved in nucleic acid metabolism increased, while the proportion of proteins involved in intercellular communication and signal transduction decreased. The representation of NPC passenger proteins in breast cancer also changes: the proportion of proteins involved in transport increases and the share of proteins involved in energy biological pathways decreases. Moreover, in the HF blood, proteins involved in the processes of apoptosis were more represented in the composition of NPCs and in the BCP blood-in the processes of active secretion. For the first time, bioinformatics approaches were used to visualize the architecture of circulating NPCs in the blood and to show that breast cancer has an increased representation of passenger proteins involved in EMT, cell proliferation, invasion, cell migration, and immune response. Using breast cancer protein data from the Human Protein Atlas (HPA) and DEPC, we found that 86% of NPC proteins in the blood of BCPs were not previously annotated in these databases. The obtained data may indirectly indicate directed protein sorting in NPCs, which, along with extracellular vesicles, can not only be diagnostically significant molecules for liquid biopsy, but can also carry out the directed transfer of genetic material from donor cells to recipient cells.

Early acquisition of S-specific Tfh clonotypes after SARS-CoV-2 vaccination is associated with the longevity of anti-S antibodies.

SARS-CoV-2 vaccines have been used worldwide to combat COVID-19 pandemic. To elucidate the factors that determine the longevity of spike (S)-specific antibodies, we traced the characteristics of S-specific T cell clonotypes together with their epitopes and anti-S antibody titers before and after BNT162b2 vaccination over time. T cell receptor (TCR) αβ sequences and mRNA expression of the S-responded T cells were investigated using single-cell TCR- and RNA-sequencing. Highly expanded 199 TCR clonotypes upon stimulation with S peptide pools were reconstituted into a reporter T cell line for the determination of epitopes and restricting HLAs. Among them, we could determine 78 S epitopes, most of which were conserved in variants of concern (VOCs). After the 2nd vaccination, T cell clonotypes highly responsive to recall S stimulation were polarized to follicular helper T (Tfh)-like cells in donors exhibiting sustained anti-S antibody titers (designated as 'sustainers'), but not in 'decliners'. Even before vaccination, S-reactive CD4+ T cell clonotypes did exist, most of which cross-reacted with environmental or symbiotic microbes. However, these clonotypes contracted after vaccination. Conversely, S-reactive clonotypes dominated after vaccination were undetectable in pre-vaccinated T cell pool, suggesting that highly responding S-reactive T cells were established by vaccination from rare clonotypes. These results suggest that de novo acquisition of memory Tfh-like cells upon vaccination may contribute to the longevity of anti-S antibody titers.

Early acquisition of S-specific Tfh clonotypes after SARS-CoV-2 vaccination is associated with the longevity of anti-S antibodies

SARS-CoV-2 vaccines have been used worldwide to combat COVID-19 pandemic. To elucidate the factors that determine the longevity of spike (S)-specific antibodies, we traced the characteristics of S-specific T cell clonotypes together with their epitopes and anti-S antibody titers before and after BNT162b2 vaccination over time. T cell receptor (TCR) αβ sequences and mRNA expression of the S-responded T cells were investigated using single-cell TCR- and RNA-sequencing. Highly expanded 199 TCR clonotypes upon stimulation with S peptide pools were reconstituted into a reporter T cell line for the determination of epitopes and restricting HLAs. Among them, we could determine 78 S epitopes, most of which were conserved in variants of concern (VOCs). After the 2nd vaccination, T cell clonotypes highly responsive to recall S stimulation were polarized to follicular helper T (Tfh)-like cells in donors exhibiting sustained anti-S antibody titers (designated as ‘sustainers’), but not in ‘decliners’. Even before vaccination, S-reactive CD4+ T cell clonotypes did exist, most of which cross-reacted with environmental or symbiotic microbes. However, these clonotypes contracted after vaccination. Conversely, S-reactive clonotypes dominated after vaccination were undetectable in pre-vaccinated T cell pool, suggesting that highly responding S-reactive T cells were established by vaccination from rare clonotypes. These results suggest that de novo acquisition of memory Tfh-like cells upon vaccination may contribute to the longevity of anti-S antibody titers.

&lt;i&gt;In vitro&lt;/i&gt; cell-based Hyperuricemia-hemotest bioassay for cytokine status evaluation in patients with gouty arthritis

Aim– to develop anin vitromethod for assessing the activity of the inflammasome under conditions of hyperuricemic stimulation of inflammatory interleukins. Material and methods.Whole blood cells of donors and patients with hyperuricemia and exacerbation of gouty arthritis diluted with RPMI were culturedin vitroin the presence of different concentrations of uric acid. The production of cytokines in the cell growth media of hematopoietic cells stimulated with uric acid was evaluated using an enzyme-linked immunosorbent assay (ELISA). Results.By simulating the hyperuricemiain vivo, anin vitrocell-based bioassay was developed to stimulate blood cells of individual donors with uric acid. Using the developedin vitroHyperuricemia-hemotest bioassay, quantitative differences were found in the production of inflammatory cytokines by the blood cells of potentially healthy donors and patients with hyperuricemia and gouty arthritis. Conclusion.As a new approach in personalized diagnostics, a hyperuricemic (HU)-hemotest system was developed, which can serve as anin vitrocell model for studying the activation of inflammasome by inflammatory signaling molecules in gouty arthritis.

High histone crotonylation modification in bovine fibroblasts promotes cell proliferation and the developmental efficiency of preimplantation nuclear transfer embryos

Lysine crotonylation (Kcr) is a recently discovered histone acylation modification that is closely associated with gene expression, cell proliferation, and the maintenance of stem cell pluripotency and indicates the transcriptional activity of genes and the regulation of various biological processes. During cell culture, the introduction of exogenous croconic acid disodium salt (Nacr) has been shown to modulate intracellular Kcr levels. Although research on Kcr has increased, its role in cell growth and proliferation and its potential regulatory mechanisms remain unclear compared to those of histone methylation and acetylation. Our investigation demonstrated that the addition of 5 mM Nacr to cultured bovine fibroblasts increased the expression of genes associated with Kcr modification, ultimately promoting cell growth and stimulating cell proliferation. Somatic cell nuclear transfer of donor cells cultured in 5 mM Nacr resulted in 38.1% blastocyst development, which was significantly greater than that in the control group (25.2%). This research is important for elucidating the crotonylation modification mechanism in fibroblast proliferation to promote the efficacy of somatic cell nuclear transfer.

Elevated cathepsin S serum levels in new-onset type 1 diabetes and autoantibody-positive siblings.

Accumulating data suggest a role for the lysosomal protease cathepsin S (CTSS) in type 1 diabetes. Circulating CTSS is increased in type 1 diabetes; however, whether CTSS has protective or deleterious effects is unclear. The study's objectives were to examine the biomarker potential of CTSS in new-onset type 1 diabetes, and to investigate the expression and secretion of CTSS in human islets and β cells. The CTSS level was analyzed in serum from children with new-onset type 1 diabetes and autoantibody-positive and -negative siblings by ELISA. The expression and secretion of CTSS were evaluated in isolated human islets and EndoC-βH5 cells by real-time qPCR, immunoblotting, and ELISA. The CTSS serum level was elevated in children with new-onset type 1 diabetes and positively associated with autoantibody status in healthy siblings. Human islets and EndoC-βH5 cells demonstrated induction and secretion of CTSS after exposure to pro-inflammatory cytokines, a model system of islet inflammation. Analysis of publicly available single-cell RNA sequencing data on human islets showed that elevated CTSS expression was exclusive for the β cells in donors with type 1 diabetes as compared to non-diabetic donors. These findings suggest a potential of CTSS as a diagnostic biomarker in type 1 diabetes.

Allogeneic haematopoietic cell transplantation for chronic myeloid leukaemia in Switzerland in the face of rapid development of effective drugs.

Until the year 2000, allogeneic haematopoietic cell transplantation (HCT) was the standard treatment for young and fit chronic myeloid leukaemia (CML) patients. CML was the main indication for allogeneic HCT. The introduction of tyrosine kinase inhibitors changed the treatment of CML patients dramatically. Allogeneic HCT was rapidly replaced by tyrosine kinase inhibitors as first-line treatment for CML, and the indication shifted to the treatment of non-responders, patients intolerant to tyrosine kinase inhibitors and patients whose CML is transforming to the accelerated phase and blast crisis. This paper describes changes in the use of transplantation technology for CML patients in the face of rapid drug development. All patients receiving a transplant for CML between 1997 and 2021 in Switzerland were included in the study. For the purpose of this analysis, time periods were analysed in quinquennia, 1997-2001 (Q1), 2002-2006 (Q2), 2007-2011 (Q3), 2012-2016 (Q4) and 2017-2021 (Q5), as the observation period spanned 25 years. Overall, 239 patients received a transplant. These included 96 in Q1, 56 in Q2, 25 in Q3, 34 in Q4 and 28 in Q5. Patient characteristics changed over time: recent patients were older and had a longer interval from diagnosis to transplantation because of tyrosine kinase inhibitor treatment. However, the proportions of patients receiving transplants during an early versus advanced disease stage differed little. Transplant technology changed, as well. Patients received intensive conditioning regimens less often due to higher age and more commonly had peripheral blood as opposed to bone marrow transplants. However, the type of stem cell donor selected did not differ. In a univariable analysis, there were no significant differences in survival, progression-free survival, non-relapse mortality, relapse incidence or incidences of acute and chronic graft-versus-host disease among the five quinquennia. In a multivariable analysis, older age, donors other than HLA-identical siblings and more advanced disease stage, but not the quinquennium, were associated with higher risk of death. Since the introduction of tyrosine kinase inhibitors haematopoietic cell transplantation has been used less frequently to treat CML. Patients in recent cohorts received transplants at an older age and later in the disease course; despite these higher risks, the outcome of allogeneic HCT has not worsened over time but has not improved, either. As the outcome is worse in advanced phases, it is important to conduct transplants before disease progression. Therefore, patients with advanced disease should be monitored closely and receive transplants in time.

Abstract PO1-07-02: Sensitive tumor detection, accurate quantification, and ER subtyping using low-pass methylome of liquid biopsy samples from patients (pts) with metastatic breast cancer (mBC)

Abstract Background The presence and amount of blood circulating tumor DNA (Tumor Content, TC) is emerging as a clinically relevant factor in many cancers, including BC. In the metastatic setting, a commonly used tumor tissue agnostic approach involves analyzing Copy Number Alterations (CNA) from low-pass whole-genome sequencing (lpWGS) by ichorCNA. However, with a lower limit of detection of 3%, it is unsuitable for low TC applications, such as monitoring disease in response to treatment. Here we report on the use of low-pass whole genome bisulfite sequencing (lpWGBS) coupled with a novel tool, METER (METhylation analyzER), to overcome current limitations of lpWGS, enabling sensitive TC detection, accurate quantification, and ER subtyping from mBC liquid biopsies. Methods METER is a computational tool to analyse TC exploiting BC-specific Differentially Methylated Sites (DMS) and Regions (DMR) in lpWGBS data. To define BC DMSs and DMRs, Rocker-meth was applied to the WGBS profiles of 30 BC tissue (BASIS dataset) and 23 healthy donor cell free DNA (cfDNA) (Fox-Fisher 2021). METER consists of three modules: 1) METER-quant, a DMS-based quantifier of TC; 2) METER-detect, a DMR-based z-score method to classify samples as TC+ (METER+) or TC- (METER-); 3) METER-subtype, to infer ER status via Robust Partial Correlation applied to ER+ vs. ER- BC DMR. We generated lpWGBS data (coverage 0.5-1X) of 135 cfDNA samples from 58 pts (45 ER+, 13 ER-, 55 (95%) up to 3 previous lines of treatment; before starting treatment (T0, n=58), after the first cycle (T1, n=25), and at progression (T2, n=22)) and 30 from healthy individuals as controls. ichorCNA using sensitive parameters (allowing normal fraction up to 0.99) was used to estimate reference TC. A leave-one-out strategy applied to the control samples was used to estimate the false discovery rate (FDR) of METER-detect classification. METER+/- pts were tested for association with OS and PFS using the log-rank test and compared with ichorCNA detection (TC by ichorCNA above or below 3%, ichorCNA+/-). Results TC of 105 cfDNA BC samples by METER-quant was concordant with estimates from the state-of-the-art tool ichorCNA (R &amp;gt;0.90, p&amp;lt; 1e-10). In 22 pts with complete longitudinal data, METER-quant median TC of 0.05 at T0 (IQR 0.02-0.12), 0.02 at T1 (0.01-0.07), and 0.06 at T2 (0.03-0.11) were obtained, with significant difference observed for T0 vs T1 and T2 vs T1 (paired Wilcoxon p&amp;lt; 0.05). Across all time points, METER-detect classified 43% of the n=42 ichorCNA- samples as METER+. The reliability and prognostic performance of METER and ichorCNA detection classification were then compared using clinical outcome data. Based on T0 data, METER+ pts had significantly worse OS than METER- (HR=4.2 CI=2.0-8.9, p&amp;lt; 0.001). This effect was stronger than using ichorCNA (HR=2.3 CI=1.3-4.0, p=0.006). Worse PFS at T0 was observed for METER+ compared with METER- pts (HR=3.7 CI=1.8-7.9, p&amp;lt; 0.001), while no significant association was observed for ichorCNA+ pts (HR=1.4 CI=0.8-2.5, p=0.2). Of note, ichorCNA-/METER+ pts (N=11) at T0 had worse PFS compared with ichorCNA-/METER- (N=11) (HR=3.7 CI 1.4-9.7, p=0.005). Considering the 73 METER+ and 53 samples with METER-quant &amp;gt;5%, METER-subtype showed an accuracy of 0.84 (CI=0.73-0.92) and 0.94 (CI=0.83-0.99) respectively in classifying ER status based on IHC. Discussion lpWGBS enables tumor tissue agnostic analysis and concurrent investigation of complementary molecular features, including CNA and DNA methylation patterns. In a small and heterogeneous cohort, METER showed comparable performance to state-of-the-art tools in terms of TC quantification (ichorCNA) and ER subtyping (IHC), while offering enhanced sensitivity and ensuring a low FDR. METER showed promising prognostic stratification capabilities, particularly for patients with low TC. Validation in an extended prospective cohort is currently ongoing. Citation Format: Marta Paoli, Agostina Nardone, Francesca Galardi, Chiara Biagioni, Dario Romagnoli, Francesca De Luca, Gian Marco Franceschini, Ilenia Migliaccio, Marta Pestrin, Giuseppina Sanna, Emanuela Risi, Luca Livraghi, Erica Moretti, Laura Biganzoli, Luca Malorni, Francesca Demichelis, Matteo Benelli. Sensitive tumor detection, accurate quantification, and ER subtyping using low-pass methylome of liquid biopsy samples from patients (pts) with metastatic breast cancer (mBC) [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-07-02.

Intercellular transfer of MHC molecules in T cell alloimmunity and allotransplantation

After transplantation of allogeneic tissues and organs, recognition by recipient T cells of donor MHC molecules initiates the pro-inflammatory adaptive immune response leading to allograft rejection. T cell allorecognition has long been known to be mediated via two distinct pathways: the direct pathway in which T cells recognize intact allogeneic MHC molecules displayed on donor cells and the indirect pathway whereby T cells recognize donor MHC peptides processed and presented by recipient antigen-presenting cells (APCs). It is believed that direct allorecognition is the driving force behind early acute allograft rejection while indirect allorecognition is involved in chronic allograft rejection, a progressive condition characterized by graft vasculopathy and tissue fibrosis. Recently, we and others have reported that after transplantation of allogeneic skin and organs, donor MHC molecules are transferred from donor cells to the host's APCs via trogocytosis or extracellular vesicles. Recipient APCs having captured donor MHC molecules can either present them to T cells in the intact form on their surface (semi-direct pathway) or the form of peptides bound to self-MHC molecules (indirect pathway). The present article provides an overview of recent studies evaluating the role of intercellular exchange of MHC molecules in T cell alloimmunity and its contribution to allograft rejection and tolerance.

Outcomes of human leukocyte antigen-matched related donor and haploidentical allogeneic hematopoietic cell transplantation recipients by immune profiles of recipients and donors

BackgroundHaploidentical (Haplo) allogeneic HCTs (alloHCT) have been used more frequently over the last decade as survival is similar to HLA-matched related donor (MRD) alloHCTs. ObjectiveWe aimed to identify donor and recipient immune signatures before alloHCT that are associated with clinically meaningful outcomes in MRD vs Haplo alloHCT recipients. Study DesignThis retrospective cohort study of 165 MRD (n=132) and Haplo (n=33) alloHCT recipients and their related donors between 2007-2019 with paired peripheral blood samples immunophenotyped for T-cell, B-cell, NK cell and dendritic cell (DC) subsets. Immune cells were quantified before alloHCT in donors and recipients; calculations of immune cell ratios were classified as high, intermediate, and low and analyzed with alloHCT outcomes. ResultsHaplo donors were younger than MRD donors (median: 35 vs 51 years), whereas Haplo recipients were older than MRD recipients (median: 68 vs 54 years), were more likely to have a Karnofsky Performance Score ≤70 (76% vs 57%), 3+ comorbidities (54% vs 47%), and were in complete remission prior to alloHCT (58% vs 42%).In MRD alloHCT, a lower ratio of CD4+ to CD8+ effector memory cells in the donor was associated with lower 4-yr overall survival (OS; 25% v 61%; p=0.009), lower 4-yr progression free survival (PFS; 25% v 58%; p=0.014) and higher incidence of 1-yr transplant-related mortality (TRM; 39% v 7%; p=0.009) in recipients. A higher ratio of CD8+ effector memory to total NK cells measured in MRD recipients was associated with a higher incidence of grade II-IV aGvHD (63% v 37%; p=0.004) but was not statistically significant for III-IV aGvHD (23% v 12%).In Haplo alloHCT, a lower ratio of total T-regulatory to CD4+ central memory cells in the donor was associated with lower 4-yr PFS (22% v 60%; p=0.0091). A higher ratio of CD4+ effector memory to CD8+ effector memory cells measured in Haplo recipients pre-alloHCT was associated with lower 4-yr OS (25% v 88%; p=0.0039). In both MRD and Haplo recipients, a higher ratio of CD4+ naïve to CD4+ central memory cells was associated with a higher incidence of grade II-IV aGvHD (64% v 38%; p=0.04). ConclusionEvaluation of pre-alloHCT immune signatures of the donor and recipient may influence clinically meaningful patient outcomes in both MRD and Haplo transplants.

Efficacy and risk of donor-derived CAR-T treatment of relapsed B-cell acute lymphoblastic leukemia after hematopoietic stem cell transplantation

The one-year survival rate for patients experiencing a relapse of B-cell acute lymphocytic leukemia (B-ALL) following hematopoietic stem cell transplantation (HSCT) is approximately 30%. Patients experiencing a relapse after allogeneic HSCT frequently encounter difficulties in obtaining autologous CAR-T products. We conducted a study involving 14 patients who received donor-derived CAR-T therapy for relapsed B-ALL following HSCT between August 2019 and May 2023 in our center. The results revealed a CR/CRi rate of 78.6% (11/14), a GVHD rate of 21.4% (3/14), and a 1-year overall survival (OS) rate of 56%. Decreased bone marrow donor cell chimerism in 9 patients recovered after CAR-T therapy. The main causes of death were disease progression and infection. Further analysis showed that GVHD (HR 7.224, 95% CI 1.42-36.82, P=0.017) and platelet recovery at 30 days (HR 6.807, 95% CI 1.61-28.83, P=0.009) are significantly associated with OS after CAR-T therapy. Based on the findings, we conclude that donor-derived CAR-T cells are effective in treating relapsed B-ALL patients following HSCT. Additionally, GVHD and poor platelet recovery impact OS, but further verification with a larger sample size is needed.

Usefulness of antibody-drug conjugate as preconditioning for hematopoietic stem cell-targeted gene therapy in wild-type and Fabry disease mouse models

BackgroundFabry disease (FD) is characterized by deficient activity of α-galactosidase A (GLA). Consequently, globotriaosylceramide (Gb3) accumulates in various organs, causing cardiac, renal, and cerebrovascular damage. Gene therapies for FD have been investigated in humans. Strong conditioning is required for hematopoietic stem cell-targeted gene therapy (HSC-GT). However, strong conditioning leads to various side effects and should be avoided. In this study, we tested antibody-based conditioning for HSC-GT in wild-type and FD model mice. MethodsAfter preconditioning with an antibody-drug conjugate, HSC-GT using a lentiviral vector was performed in wild-type and Fabry model mice. In the wild-type experiment, the EGFP gene was introduced into HSCs and transplanted into preconditioned mice, and donor chimerism and EGFP expression were analyzed. In the FD mouse model, the GLA gene was introduced into HSCs and transplanted into preconditioned Fabry mice. GLA activity and Gb3 accumulation in the organs were analyzed. ResultsIn the wild-type mouse experiment, when anti-CD45 antibody-drug conjugate was used, the percentage of donor cells at 6 months was 64.5%, and 69.6% of engrafted donor peripheral blood expressed EGFP. When anti-CD117 antibody-drug conjugate and ATG were used, the percentage of donor cells at 6 months was 80.7%, and 73.4% of engrafted donor peripheral blood expressed EGFP. Although large variations in GLA activity among mice were observed in the FD mouse experiment for both preconditioning regimens, Gb3 was significantly reduced in many organs. ConclusionsAntibody-based preconditioning may be an alternative preconditioning strategy for HSC-GT for treating FD.