Experimental hematology最新文献

{"title":"2029 – INTRAVITAL IMAGING OF CALCIUM NETWORK TOPOLOGY REVEALED THE IMMUNE-MODULATORY LOCI IN THE BONE MARROW","authors":"Cih-Li Hong, Montgomery Whalen, Kevin Lee, Shinya Yari, Adam Tyrlik, Arutyun Bagramyan, Laura Calvi, Maria Maryanovich, Shu-Chi Yeh, Charles Lin","doi":"10.1016/j.exphem.2026.105557","DOIUrl":"10.1016/j.exphem.2026.105557","url":null,"abstract":"<div><div>Intercellular communications through calcium signaling orchestrates coordinated cell functions across diverse tissues. Bone marrow stromal cells (BMSCs) form an extended 3D network in the marrow and secrete cytokines essential for regulating blood and immune cell formation. Yet, the degree of coordination and heterogeneity among the BMSCs in the interconnected network remain poorly understood. Here, we developed an intravital calcium imaging platform using LepR-cre; Salsa6f mice, in which tdTomato and a calcium flux indicator (GCaMP6f) are expressed in BMSC lineages. We identified a subset of BMSCs that communicate via intercellular calcium waves (ICWs). The ICWs are provoked by acute inflammatory challenges (lipopolysaccharide [LPS], 1.4 mg/kg), and follow circadian rhythms. Further analyses from the single-cell RNA sequencing data suggest that the BMSC subset express high level of leukocyte chemoattractant Ccl2. Validations using intravital tracking confirmed that ICW initiation led to aggregation of CCR2+ leukocytes within 2 hours after LPS administration, forming “hot spots” within the systemic inflammatory landscape. As gap junctions have been reported to regulate timed cytokine secretion, we next generated triple transgenic LepR-cre; Cx43 floxed; Salsa6f mice. Cx43 deficiency reduced ICWs and led to a more diffused CCR2 cell distribution in contrast to the designated hot spots found in the WT mice. Functionally, Cx43 deficiency blunted the responses of IL-1β and IL-10 in the bone marrow after LPS challenge, whereas CXCL12 was not affected. Together, our intravital imaging toolbox uncovered the presence of immune modulatory loci in the bone marrow, where BMSCs coordinate through ICWs to work in spatially and temporally controlled manner.</div></div><div>Intercellular communications through calcium signaling orchestrates coordinated cell functions across diverse tissues. Bone marrow stromal cells (BMSCs) form an extended 3D network in the marrow and secrete cytokines essential for regulating blood and immune cell formation. Yet, the degree of coordination and heterogeneity among the BMSCs in the interconnected network remain poorly understood. Here, we developed an intravital calcium imaging platform using LepR-cre; Salsa6f mice, in which tdTomato and a calcium flux indicator (GCaMP6f) are expressed in BMSC lineages. We identified a subset of BMSCs that communicate via intercellular calcium waves (ICWs). The ICWs are provoked by acute inflammatory challenges (lipopolysaccharide [LPS], 1.4 mg/kg), and follow circadian rhythms. Further analyses from the single-cell RNA sequencing data suggest that the BMSC subset express high level of leukocyte chemoattractant Ccl2. Validations using intravital tracking confirmed that ICW initiation led to aggregation of CCR2+ leukocytes within 2 hours after LPS administration, forming “hot spots” within the systemic inflammatory landscape. As gap junctions have been reported to regulate timed cytokin","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105557"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2014 – DOWN SYNDROME FETAL LIVER HEMATOPOIETIC PROGENITORS FAIL TO PROVIDE A PERMISSIVE CELL CONTEXT FOR KMT2A::AFF1 INFANT ACUTE LYMPHOBLASTIC LEUKAEMIA INITIATION","authors":"Lucy Hamer, Thomas Jackson, Natalina Elliott, Emily Neil, Zhenhua Li, Jun Yang, Ananya Mahadevan, Joe Cross, Rebecca Ling, Irene Roberts, Anindita Roy","doi":"10.1016/j.exphem.2026.105542","DOIUrl":"10.1016/j.exphem.2026.105542","url":null,"abstract":"<div><div>Infant acute lymphoblastic leukemia (iALL) arises in utero, chiefly by KMT2A::AFF1 translocation. Risk of childhood ALL (chALL) is increased 27-fold in Down Syndrome (DS) but there are no reports of iALL. DS fetal hematopoietic progenitors may not be permissive for one-hit iALL transformation.</div><div>We induced KMT2A::AFF1 translocation in disomic (normal) primary human fetal liver (N FL) and DS FL CD34<sup>+</sup> cells by CRISPR-Cas9. Translocation was detected at 12h by droplet digital PCR. Edited CRISPR KMT2A::AFF1 cells were cultured on MS-5 stroma or injected into irradiated NSG mice to model transformation. Transformed populations were characterized with immunophenotyping and KMT2A::AFF1 quantitative polymerase chain reaction (qPCR). Xenograft bone marrow was analyzed using RNA-seq and compared with patient data.</div><div>KMT2A::AFF1 editing efficiency was similar in DS FL as in N FL (1.4% vs. 1.3%, n = 9). However, the transformation efficiency of CRISPR KMT2A::AFF1 DS FL was significantly reduced in vitro with 28.2% of wells (n = 5, 104 wells) transforming compared with 91.1% in N FL (n = 6, 82 wells, <em>p</em> < 0.001). In both N and DS FL, transformed wells showed KMT2A::AFF1<sup>+</sup> B-lineage expansion and lymphoid-primed multipotent progenitors transformed most efficiently. N FL CRISPR KMT2A::AFF1 xenografts model ProB iALL with splenomegaly and CNS infiltration (7 out of 8 mice, median latency 21 weeks). DS FL CRISPR KMT2A::AFF1 xenografts rarely developed leukemia (3 out of 12). Median latency was prolonged (37 weeks, <em>p</em> < 0.001), and there was no splenomegaly or CNS disease. Some DS FL CRISPR KMT2A::AFF1 primary mice developed preleukemia (5 out of 12) in which blasts did not cause symptomatic disease or serially engraft. Transcriptionally, N FL CRISPR KMT2A::AFF1 xenografts resemble high-risk patient iALL but DS FL xenoblasts mimic chALL.</div><div>Our functional and molecular data indicate that DS FL does not provide the optimal fetal context to permit aggressive iALL initiation.</div></div><div>Infant acute lymphoblastic leukemia (iALL) arises in utero, chiefly by KMT2A::AFF1 translocation. Risk of childhood ALL (chALL) is increased 27-fold in Down Syndrome (DS) but there are no reports of iALL. DS fetal hematopoietic progenitors may not be permissive for one-hit iALL transformation.</div><div>We induced KMT2A::AFF1 translocation in disomic (normal) primary human fetal liver (N FL) and DS FL CD34<sup>+</sup> cells by CRISPR-Cas9. Translocation was detected at 12h by droplet digital PCR. Edited CRISPR KMT2A::AFF1 cells were cultured on MS-5 stroma or injected into irradiated NSG mice to model transformation. Transformed populations were characterized with immunophenotyping and KMT2A::AFF1 quantitative polymerase chain reaction (qPCR). Xenograft bone marrow was analyzed using RNA-seq and compared with patient data.</div><div>KMT2A::AFF1 editing efficiency was similar in DS FL as in N FL (1.4% vs. ","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105542"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"1008 – CLONAL HEMATOPOIESIS IN THE HUMAN BRAIN","authors":"Siddhartha Jaiswal","doi":"10.1016/j.exphem.2026.105504","DOIUrl":"10.1016/j.exphem.2026.105504","url":null,"abstract":"<div><div>The brain has been assumed to be a site where circulating blood cells are excluded from entering under normal conditions. The resident immune cells of the brain, called microglia, originate from hematopoietic precursors in the yolk sac that self-renew for life without further contribution from adult hematopoiesis, according to current dogma. Microglia, which resemble macrophages in other tissues, are important for many neurologic processes and are implicated in brain disorders, including Alzheimer’s disease. Here, I presented our recent work challenging this paradigm. I showed that hematopoietic stem cell-derived myeloid cells can colonize the human brain in aging and differentiate into bona fide microglia. I also discussed the implications of these findings for Alzheimer’s disease.</div></div><div>The brain has been assumed to be a site where circulating blood cells are excluded from entering under normal conditions. The resident immune cells of the brain, called microglia, originate from hematopoietic precursors in the yolk sac that self-renew for life without further contribution from adult hematopoiesis, according to current dogma. Microglia, which resemble macrophages in other tissues, are important for many neurologic processes and are implicated in brain disorders, including Alzheimer’s disease. Here, I presented our recent work challenging this paradigm. I showed that hematopoietic stem cell-derived myeloid cells can colonize the human brain in aging and differentiate into bona fide microglia. I also discussed the implications of these findings for Alzheimer’s disease.</div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105504"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3271 – DISSECTING THE ROLE OF RETINOIC ACID SIGNALING IN HUMAN CHRONIC LYMPHOID LEUKEMIA","authors":"Martina Franchino,&nbsp;Aurora Maurizio,&nbsp;Federica Nardi,&nbsp;Lenti Elisa,&nbsp;Elisabetta Campodoni,&nbsp;Alessandro Gulino,&nbsp;Pamela Ranghetti,&nbsp;Lydia Scarfò,&nbsp;Anna Tosato,&nbsp;Daniela Talarico,&nbsp;Paolo Ghia,&nbsp;Kabanova Anna,&nbsp;Monica Sandri,&nbsp;Vincenzo Russo,&nbsp;Claudio Tripodo,&nbsp;Andrea Brendolan","doi":"10.1016/j.exphem.2026.105875","DOIUrl":"10.1016/j.exphem.2026.105875","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Background&lt;/h3&gt;&lt;div&gt;The microenvironment of secondary lymphoid organs is composed of various cell types, including fibroblastic reticular cells (FRCs), which produce chemokines, extracellular matrix (ECM), and survival signals, thereby maintaining the structural organization, guiding adhesion and motility, and promoting survival of normal and malignant B cells such as chronic lymphocytic leukemia (CLL) cells.&lt;/div&gt;&lt;div&gt;We previously identified a retinoic acid (RA)-dependent FRC-leukemia crosstalk during CLL progression in mice and demonstrated that pharmacologic inhibition of the RA pathway reduces tissue infiltration and CLL progression in preclinical models. Specifically, the pharmacologic inhibition of RA signaling was shown to reduce the expression of genes involved in cell adhesion, ECM organization, and chemokine signaling.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;The microenvironment of secondary lymphoid organs is composed of various cell types, including fibroblastic reticular cells (FRCs), which produce chemokines, extracellular matrix (ECM), and survival signals, thereby maintaining the structural organization, guiding adhesion and motility, and promoting survival of normal and malignant B cells such as chronic lymphocytic leukemia (CLL) cells.&lt;/div&gt;&lt;div&gt;We previously identified a retinoic acid (RA)-dependent FRC-leukemia crosstalk during CLL progression in mice and demonstrated that pharmacologic inhibition of the RA pathway reduces tissue infiltration and CLL progression in preclinical models. Specifically, the pharmacologic inhibition of RA signaling was shown to reduce the expression of genes involved in cell adhesion, ECM organization, and chemokine signaling.&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Aim&lt;/h3&gt;&lt;div&gt;Investigate the role(s) of the RA pathway in human FRC-CLL crosstalk using CLL lymph node (LN) biopsies and different in vitro models recapitulating the lymphoid microenvironment.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Investigate the role(s) of the RA pathway in human FRC-CLL crosstalk using CLL lymph node (LN) biopsies and different in vitro models recapitulating the lymphoid microenvironment.&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Results&lt;/h3&gt;&lt;div&gt;RNA-scope analysis revealed upregulation of genes involved in RA synthesis, degradation, and signaling in human CLL (hCLL) LN biopsies, compared with control tissues. Specifically, we found that retinoid X receptor α (RXRa), an RA nuclear receptor, is overexpressed in hCLL cells compared with control B cells. Bulk RNA sequencing (RNA-seq) was performed to evaluate changes in gene expression upon RXR inhibition. The results revealed that inhibition of RA signaling in CLL and FRC is associated with deregulation of immune, chemokine, and adhesion pathways. Using in vitro coculture models, we further demonstrated that inhibition of RXRa disrupts CLL-FRC interactions and promotes mobilization of leukemic cells.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;RNA-scope analysis revealed upregulation of genes involved in RA synthesis, degradation, and signaling in human CLL (hCLL) LN biopsies, compared ","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105875"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2045 – ORIGINS OF IMMUNE RESILIENCE: NEONATAL HEMATOPOIETIC STEM CELLS ENCODE LIFELONG IMMUNE COMPETENCE AND HEALTH SPAN","authors":"Marcel Rommel,&nbsp;Atesh Worthington,&nbsp;Alessandra Rodriguez y Baena,&nbsp;Shally Saini,&nbsp;Bryce Manso,&nbsp;Stephanie Smith-Berdan,&nbsp;Angela Deguzman,&nbsp;David Boyd,&nbsp;E. Camilla Forsberg","doi":"10.1016/j.exphem.2026.105573","DOIUrl":"10.1016/j.exphem.2026.105573","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Durable immune competence is essential for healthy aging and successful hematopoietic stem cell (HSC) therapies. Developmental hematopoiesis is functionally heterogeneous, with distinct HSC subsets shaping lifelong immune architecture. Using the FlkSwitch lineage tracing model, we identified a previously unrecognized population of developmentally restricted HSCs (drHSCs) that do not persist in situ as HSCs in adult bone marrow, yet retain robust reconstitution capacity upon transplantation. This raises a fundamental question: Is HSC persistence intrinsically programmed or shaped by irradiation-induced niche perturbation? To decouple intrinsic HSC programming from irradiation-induced niche effects, we transplanted HSCs across life stages into unconditioned NBSGW mice.&lt;/div&gt;&lt;div&gt;In contrast to the myeloid biased output of neonatal, adult, and aged HSCs, neonatal drHSCs sustained serial, multilineage reconstitution for over a year with durable lymphoid bias. Despite a smaller HSC pool, drHSCs more effectively reconstituted circulating and tissue-resident lymphoid compartments, including B1a cells, marginal zone B cells, and γδ T cells across multiple organs. Enhanced output is functionally reflected by elevated IgM and protection against respiratory influenza infection. By eliminating confounding irradiation effects, the unconditioned model shows that drHSC self-renewal and multilineage reconstitution are intrinsic properties. These features are underpinned by a distinct epigenetic landscape, characterized by dynamic cis-regulatory element accessibility and persistence of the developmental regulator Lin28b, which distinguishes drHSCs from adult and aged HSCs.&lt;/div&gt;&lt;div&gt;Collectively, neonatal HSC programs encode durable immune resilience, redefining developmental heterogeneity as a tractable target for improving health span, immune recovery, and transplantation therapies.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Durable immune competence is essential for healthy aging and successful hematopoietic stem cell (HSC) therapies. Developmental hematopoiesis is functionally heterogeneous, with distinct HSC subsets shaping lifelong immune architecture. Using the FlkSwitch lineage tracing model, we identified a previously unrecognized population of developmentally restricted HSCs (drHSCs) that do not persist in situ as HSCs in adult bone marrow, yet retain robust reconstitution capacity upon transplantation. This raises a fundamental question: Is HSC persistence intrinsically programmed or shaped by irradiation-induced niche perturbation? To decouple intrinsic HSC programming from irradiation-induced niche effects, we transplanted HSCs across life stages into unconditioned NBSGW mice.&lt;/div&gt;&lt;div&gt;In contrast to the myeloid biased output of neonatal, adult, and aged HSCs, neonatal drHSCs sustained serial, multilineage reconstitution for over a year with durable lymphoid bias. Despite a smaller HSC pool, drHSCs more effectively reconstituted circulating and tissue-resident lymph","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105573"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3273 – APELIN SIGNALING ACTS AS A MOLECULAR SWITCH BETWEEN ENDOTHELIAL AND HEMATOPOIETIC STEM CELL FATES","authors":"Christian Helker,&nbsp;Jean Eberlein,&nbsp;Nadja Groos","doi":"10.1016/j.exphem.2026.105877","DOIUrl":"10.1016/j.exphem.2026.105877","url":null,"abstract":"<div><div>Hematopoietic stem and progenitor cells (HSPCs) emerge from arterial endothelial cells (ECs) through a process termed endothelial-to-hematopoietic transition (EHT), a process induced by paracrine signals and driven by a transcriptional cascade. Despite inductive signals being broadly received by ECs in the dorsal aorta (DA), only a subset of ECs undergoes EHT, whereas others maintain their vascular identity. The molecular mechanisms that determine this selective fate decision remain poorly understood. Here, we discover Apelin signaling as a critical regulator of cell fates in the DA, acting as a molecular switch to balance vascular and hematopoietic identities. We show that Apelin receptor (Aplnr)-expressing ECs retain their arterial identity, whereas Aplnr nonexpressing ECs are primed to become hemogenic endothelial cells (HECs) and transition into HSPCs. Loss of Apelin signaling leads to excessive EC-to-HEC conversion and increased HSPC numbers. Conversely, forced Aplnr expression abolishes HSPC formation by maintaining EC identity. These findings reveal that Apelin signaling regulates HSPC formation by preserving endothelial identity. In summary, our findings establish Apelin signaling as a critical regulator for balancing endothelial and hematopoietic fates.</div></div><div>Hematopoietic stem and progenitor cells (HSPCs) emerge from arterial endothelial cells (ECs) through a process termed endothelial-to-hematopoietic transition (EHT), a process induced by paracrine signals and driven by a transcriptional cascade. Despite inductive signals being broadly received by ECs in the dorsal aorta (DA), only a subset of ECs undergoes EHT, whereas others maintain their vascular identity. The molecular mechanisms that determine this selective fate decision remain poorly understood. Here, we discover Apelin signaling as a critical regulator of cell fates in the DA, acting as a molecular switch to balance vascular and hematopoietic identities. We show that Apelin receptor (Aplnr)-expressing ECs retain their arterial identity, whereas Aplnr nonexpressing ECs are primed to become hemogenic endothelial cells (HECs) and transition into HSPCs. Loss of Apelin signaling leads to excessive EC-to-HEC conversion and increased HSPC numbers. Conversely, forced Aplnr expression abolishes HSPC formation by maintaining EC identity. These findings reveal that Apelin signaling regulates HSPC formation by preserving endothelial identity. In summary, our findings establish Apelin signaling as a critical regulator for balancing endothelial and hematopoietic fates.</div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105877"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2002 – PERTURBATION OF LEUKEMIC STEM CELL STATES REVEALS A TGFβ-DRIVEN NICHE REMODELING PROGRAM IN AML","authors":"Karin Prummel,&nbsp;Anna Mathioudaki,&nbsp;Ivan Berest,&nbsp;Shubhankar Sood,&nbsp;Lixiazi He,&nbsp;Thorsten Richter,&nbsp;Yagmur Baskan,&nbsp;Clarissa Holitsch,&nbsp;Rim Moussa,&nbsp;Robert Reinhardt,&nbsp;Swati Garg,&nbsp;Sinem Saka,&nbsp;Konstantinos Kokkaliaris,&nbsp;Marieke Essers,&nbsp;Caroline Pabst,&nbsp;Judith Zaugg","doi":"10.1016/j.exphem.2026.105530","DOIUrl":"10.1016/j.exphem.2026.105530","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The bone marrow (BM) niche regulates hematopoietic stem cell function and contributes to therapy resistance and relapse in acute myeloid leukemia (AML). However, how defined leukemic stem cell (LSC) states remodel their direct niche remains incompletely understood.&lt;/div&gt;&lt;div&gt;Here, we combined genetically controlled in vivo perturbation models with scRNA-seq, 3D imaging, and functional assays to dissect LSC-driven niche remodeling. We used NPM1/FLT3-ITD/DNMT3A AML xenografts with wild-type or knockout of LSC regulator HLF to model LSChigh and LSClow conditions. Human leukemic and mouse stromal compartments were profiled at single-cell resolution, followed by cell–cell communication and gene regulatory network analyses.&lt;/div&gt;&lt;div&gt;AML induced niche remodeling, with expansion of Cxcl12⁺ adipogenic progenitors and reduction of osteo-lineage populations, particularly in LSChigh AML. This was accompanied by expansion of Fmod⁺ and Cd34⁺ fibroblasts.&lt;/div&gt;&lt;div&gt;Single-cell analysis revealed heterogeneity within AML, including quiescent, stress-adapted, and proliferative LSC states enriched in LSChigh AML, whereas LSClow showed increased myeloid and erythroid blast states. Distinct LSC subsets expressed TGFB1, IL1B, and other niche-modulating factors. Ligand prioritization identified TGFβ as a dominant LSC-derived signal. Fmod⁺ fibroblasts showed elevated TGFβ activity, and Creb3l1 was associated with fibroblast expansion, defining a pro-fibrotic state. In BM MSC–AML cocultures, LSChigh AML recapitulated this in vivo phenotype by inducing an Fmod⁺ fibroblast-like program with increased TGFβ activity and Creb3l1 regulon upregulation. Perturbations showed that TGFβ signaling and CREB3L1 modulation alter stromal states and leukemic cell retention.&lt;/div&gt;&lt;div&gt;Together, this work links LSC heterogeneity to microenvironmental reprogramming and identifies an LSC–TGFβ–CREB3L1 axis as a potential therapeutic target in AML.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;The bone marrow (BM) niche regulates hematopoietic stem cell function and contributes to therapy resistance and relapse in acute myeloid leukemia (AML). However, how defined leukemic stem cell (LSC) states remodel their direct niche remains incompletely understood.&lt;/div&gt;&lt;div&gt;Here, we combined genetically controlled in vivo perturbation models with scRNA-seq, 3D imaging, and functional assays to dissect LSC-driven niche remodeling. We used NPM1/FLT3-ITD/DNMT3A AML xenografts with wild-type or knockout of LSC regulator HLF to model LSChigh and LSClow conditions. Human leukemic and mouse stromal compartments were profiled at single-cell resolution, followed by cell–cell communication and gene regulatory network analyses.&lt;/div&gt;&lt;div&gt;AML induced niche remodeling, with expansion of Cxcl12⁺ adipogenic progenitors and reduction of osteo-lineage populations, particularly in LSChigh AML. This was accompanied by expansion of Fmod⁺ and Cd34⁺ fibroblasts.&lt;/div&gt;&lt;div&gt;Single-cell analysis revealed heterogeneity within AML, including quiesc","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105530"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2026 – SCALABLE SINGLE-CELL DNA METHYLATION REVEALS A STEPWISE EPIGENETIC LOGIC DISRUPTED IN CLONAL HEMATOPOIESIS","authors":"Alba Rodriguez Meira,&nbsp;Sander Lambo,&nbsp;Rony Chanoch-Myers,&nbsp;Carolina Varona-Arguelles,&nbsp;Paul Kaegy,&nbsp;Thomas Heim,&nbsp;Salvador Casani-Galdon,&nbsp;Peter van Galen,&nbsp;Volker Hovestadt,&nbsp;Bradley Bernstein","doi":"10.1016/j.exphem.2026.105554","DOIUrl":"10.1016/j.exphem.2026.105554","url":null,"abstract":"&lt;div&gt;&lt;div&gt;DNA methylation at CpG dinucleotides is a critical regulator of cell identity and becomes universally disrupted during hematopoietic aging and clonal evolution. Current single-cell DNA methylation technologies are limited by either low throughput or low CpG capture rates, rendering them insufficient to resolve heterogeneous cellular hierarchies across hematopoietic differentiation. To tackle this limitation, we developed DREAM-seq, a scalable single-cell DNA methylation technology which profiles &gt;6,000 methylomes per experiment and captures 440,000 CpGs per cell.&lt;/div&gt;&lt;div&gt;We leveraged DREAM-seq to analyze 42,758 single-cell methylomes from human blood and bone marrow. We discovered that hematopoietic differentiation follows a stepwise demethylation of enhancers. Demethylation initiates from hypomethylated domains in stem cells, maintained by high CpG density and CTCF binding, and widens across regulatory regions through differentiation, whereas lineage commitment is defined by CpG island hypermethylation of stem cell genes including HOXA9. This supports a model by which progressive demethylation primes lineage identity and methylation gains mark terminal fates.&lt;/div&gt;&lt;div&gt;Analysis of 10,305 cells from three CHIP donors identified a distinct TET2-mutant cluster characterized by enhancer and Polycomb-site hypermethylation (&lt;em&gt;p&lt;/em&gt; = 7.73 × 10⁻⁹), consistent with impaired differentiation and retention of stem cell programs. These findings suggest that TET2 loss-of-function co-opts the methylation logic of hematopoietic differentiation to promote clonal expansion.&lt;/div&gt;&lt;div&gt;Overall, DREAM-seq establishes a scalable framework for tissue-level single-cell methylation profiling, reveals the stepwise methylation logic governing hematopoietic differentiation and how it is co-opted in clonal hematopoiesis. These findings pave the way for understanding epigenetic drivers of clonal dominance in age-related blood disorders.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;DNA methylation at CpG dinucleotides is a critical regulator of cell identity and becomes universally disrupted during hematopoietic aging and clonal evolution. Current single-cell DNA methylation technologies are limited by either low throughput or low CpG capture rates, rendering them insufficient to resolve heterogeneous cellular hierarchies across hematopoietic differentiation. To tackle this limitation, we developed DREAM-seq, a scalable single-cell DNA methylation technology which profiles &gt;6,000 methylomes per experiment and captures 440,000 CpGs per cell.&lt;/div&gt;&lt;div&gt;We leveraged DREAM-seq to analyze 42,758 single-cell methylomes from human blood and bone marrow. We discovered that hematopoietic differentiation follows a stepwise demethylation of enhancers. Demethylation initiates from hypomethylated domains in stem cells, maintained by high CpG density and CTCF binding, and widens across regulatory regions through differentiation, whereas lineage commitment is defined by CpG island hypermethylation","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105554"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2011 – PATHWAY-GUIDED INTERCEPTION OF DOWN SYNDROME-ASSOCIATED LEUKEMOGENESIS","authors":"Anna-lena Schmell,&nbsp;Kristof Meier,&nbsp;José Gonçalves-Dias,&nbsp;Konstantin Schuschel,&nbsp;Hasan Issa,&nbsp;Sarada Achyutuni,&nbsp;Jian Xu,&nbsp;Raj Bhayadia,&nbsp;Dirk Heckl,&nbsp;Jan-Henning Klusmann","doi":"10.1016/j.exphem.2026.105539","DOIUrl":"10.1016/j.exphem.2026.105539","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Preventing leukemia remains one of the most ambitious goals in oncology. Myeloid leukemia associated with Down syndrome (ML-DS) offers a unique opportunity, as it evolves from a clinically detectable preleukemia, transient abnormal myelopoiesis (TAM). TAM arises in 30% of neonates with Down syndrome and progresses in 20% of cases. Defined by trisomy 21 and GATA1 mutations resulting in the truncated transcription factor GATA1s. To identify vulnerabilities, we performed CRISPR/Cas9-based dropout screens in a murine fetal hematopoietic stem/progenitor cell model engineered to express GATA1s in the context of chromosome 21 oncogene overexpression. A custom sgRNA library targeting genes linked to United States Food and Drug Administration (FDA)-approved drugs enabled mapping from genetic dependency to therapeutic candidate. Integration of functional screening data with patient-derived transcriptomes, gene essentiality scores, and pathway enrichment analyses revealed a reliance of TAM cells on IMPDH2 and the de novo purine biosynthesis pathway. Treatment with mycophenolate mofetil (MMF), a clinically established inhibitor with a favorable safety profile, induced apoptosis in TAM models and ML-DS cell lines, whereas healthy CD34&lt;sup&gt;+&lt;/sup&gt; progenitors are largely spared. Synergy studies have shown promising results when combining MMF with BCL2/XL inhibitors. Transcriptomic analyses revealed reciprocal adaptive circuitry between purine biosynthesis and anti-apoptotic signaling, explaining the mechanistic basis of synergy. Metabolomic phenotyping of treated primary TAM samples demonstrated that combination therapy in particular induced synergistic metabolic collapse by disrupting the cells compensatory networks. In vivo treatment of the preleukemic model conferred significant survival benefit, supporting feasibility of leukemia interception by targeting purine metabolism and survival signaling before malignant transformation.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Preventing leukemia remains one of the most ambitious goals in oncology. Myeloid leukemia associated with Down syndrome (ML-DS) offers a unique opportunity, as it evolves from a clinically detectable preleukemia, transient abnormal myelopoiesis (TAM). TAM arises in 30% of neonates with Down syndrome and progresses in 20% of cases. Defined by trisomy 21 and GATA1 mutations resulting in the truncated transcription factor GATA1s. To identify vulnerabilities, we performed CRISPR/Cas9-based dropout screens in a murine fetal hematopoietic stem/progenitor cell model engineered to express GATA1s in the context of chromosome 21 oncogene overexpression. A custom sgRNA library targeting genes linked to United States Food and Drug Administration (FDA)-approved drugs enabled mapping from genetic dependency to therapeutic candidate. Integration of functional screening data with patient-derived transcriptomes, gene essentiality scores, and pathway enrichment analyses revealed a reliance of TAM cells on IMPDH2 and the de n","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105539"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2017 – ARID1B-DEPENDENT ENHANCER REWIRING SUSTAINS KMT2A-MLLT3 LEUKEMIA AND EXPOSES A THERAPEUTIC VULNERABILITY","authors":"Jinyu Su,&nbsp;Sachin Pundhir,&nbsp;Marta Tapia,&nbsp;Adrija Kalvisa,&nbsp;Mikkel Schuster,&nbsp;Ying Ge,&nbsp;Linea Laursen,&nbsp;Maria Madsen,&nbsp;Jesper Madsen,&nbsp;Juerg Schwaller,&nbsp;Susanne Mandrup,&nbsp;Bo Porse","doi":"10.1016/j.exphem.2026.105545","DOIUrl":"10.1016/j.exphem.2026.105545","url":null,"abstract":"&lt;div&gt;&lt;div&gt;KMT2A-rearranged acute myeloid leukemia (AML), one of the most treatment-refractory leukemic subtypes, is driven by fusion protein-mediated promoter hijacking of self-renewal genes such as HOXA9 and MEIS1. However, how these direct targets promote genome-wide transcriptional reprogramming remains incompletely resolved. Using a doxycycline-inducible KMT2A-MLLT3 mouse AML model combined with epigenomic profiling (ATAC-seq, ChIP-seq, promoter capture Hi-C), we demonstrate that KMT2A-MLLT3 supports the establishment of a two-phase oncogenic circuit by directly driving the expression of a set of core target genes, including HOXA9, MEIS1, and ARID1B, which subsequently unleashes a major remodeling of the enhancer landscape to sustain leukemogenesis. Pooled CRISPR knockout screens confirmed the functional requirement of these leukemia-activated enhancers for leukemic growth. We identify ARID1B, a subunit of the cBAF chromatin remodeling complex, as a key mediator of enhancer remodeling. Specifically, ARID1B supports accessibility at leukemia-activated enhancers, and its loss selectively collapses the enhancer program and impairs leukemic, but not normal hematopoietic, growth, across species. Clinically, high ARID1B expression correlates with earlier disease onset and leukemic stem cell transcriptional signatures. We further demonstrate that strengthening of the ARID1B-driven enhancer network is associated with BET inhibitor resistance, which can be overcome by combined cBAF and BET inhibition. Thus, our work identifies ARID1B-mediated enhancer remodeling as a key oncogenic driver in KMT2A-rearranged AML with potential clinical implications.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;KMT2A-rearranged acute myeloid leukemia (AML), one of the most treatment-refractory leukemic subtypes, is driven by fusion protein-mediated promoter hijacking of self-renewal genes such as HOXA9 and MEIS1. However, how these direct targets promote genome-wide transcriptional reprogramming remains incompletely resolved. Using a doxycycline-inducible KMT2A-MLLT3 mouse AML model combined with epigenomic profiling (ATAC-seq, ChIP-seq, promoter capture Hi-C), we demonstrate that KMT2A-MLLT3 supports the establishment of a two-phase oncogenic circuit by directly driving the expression of a set of core target genes, including HOXA9, MEIS1, and ARID1B, which subsequently unleashes a major remodeling of the enhancer landscape to sustain leukemogenesis. Pooled CRISPR knockout screens confirmed the functional requirement of these leukemia-activated enhancers for leukemic growth. We identify ARID1B, a subunit of the cBAF chromatin remodeling complex, as a key mediator of enhancer remodeling. Specifically, ARID1B supports accessibility at leukemia-activated enhancers, and its loss selectively collapses the enhancer program and impairs leukemic, but not normal hematopoietic, growth, across species. Clinically, high ARID1B expression correlates with earlier disease onset and leukemic stem cell transcriptio","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105545"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}