Experimental hematology最新文献

{"title":"2027 – DEVELOPMENTAL STAGE SHAPES LINEAGE FATE AND REVEALS A TARGETABLE PRELEUKEMIC STATE IN BCR::ABL1-DRIVEN LEUKEMIA","authors":"Miguel Quijada-Alamo, Grace Freed, Nikita Poddar, Saul Carcamo, Persephone Fiore, Isabella Martinez, Mimi Zhang, Ke Wang, Subrina Autar, Shayan Saniei, Clifford Chao, Lois Kelly, Zayna Diaz, Levan Mekerishvil, Franco Izzo, Dan Hasson, Elvin Wagenblast","doi":"10.1016/j.exphem.2026.105555","DOIUrl":"10.1016/j.exphem.2026.105555","url":null,"abstract":"<div><div>Clonal hematopoiesis, predominantly linked to myeloid malignancies, has established that premalignant stem cell states can precede overt disease; analogous lymphoid preleukemic states remain poorly defined. BCR::ABL1 offers a unique model to dissect how a shared lesion drives distinct phenotypes: its two major isoforms (p190, p210) preferentially associate with B-cell acute lymphoblastic leukemia (B-ALL) and chronic myeloid leukemia (CML), respectively. We generated humanized xenograft models by CRISPR/Cas9 engineering of human primary hematopoietic stem cells (HSCs) across four developmental states and performed integrated single-cell RNA-seq and ATAC-seq across >200,000 cells. BCR::ABL1-driven transformation was strikingly isoform- and developmental state-dependent: in adult HSCs, p210 induced a CML-like myeloid disease, whereas p190 promoted lymphoid-biased output. Early developmental HSCs did not support CML-like transformation, indicating that CML fate requires adults-stage HSCs and p210 signaling. Mechanistically, adult HSCs exhibited higher baseline chromatin accessibility at CEBP-family motifs than early development HSCs, further amplified by p210, supporting a model in which developmentally-defined epigenetic priming cooperates with oncogenic signaling to dictate lineage fate. Across developmental states, both isoforms expanded a distinct ProB_VDJ transcriptional state consistent with a lymphoid preleukemic maturation arrest marked by inflammatory activation (TNF-α, IFN-γ). BCR::ABL1⁺ HSCs also showed reduced quiescence and increased oxidative phosphorylation (OXPHOS); OXPHOS inhibition with metformin significantly reduced lymphoid preleukemic expansion in vivo. Together, developmental state constrains BCR::ABL1 lineage fate through chromatin accessibility and defines a conserved metabolic vulnerability of a lymphoid preleukemic stem cell state.</div></div><div>Clonal hematopoiesis, predominantly linked to myeloid malignancies, has established that premalignant stem cell states can precede overt disease; analogous lymphoid preleukemic states remain poorly defined. BCR::ABL1 offers a unique model to dissect how a shared lesion drives distinct phenotypes: its two major isoforms (p190, p210) preferentially associate with B-cell acute lymphoblastic leukemia (B-ALL) and chronic myeloid leukemia (CML), respectively. We generated humanized xenograft models by CRISPR/Cas9 engineering of human primary hematopoietic stem cells (HSCs) across four developmental states and performed integrated single-cell RNA-seq and ATAC-seq across >200,000 cells. BCR::ABL1-driven transformation was strikingly isoform- and developmental state-dependent: in adult HSCs, p210 induced a CML-like myeloid disease, whereas p190 promoted lymphoid-biased output. Early developmental HSCs did not support CML-like transformation, indicating that CML fate requires adults-stage HSCs and p210 signaling. Mechanistically, adult HSCs exhibited higher baseline chromati","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105555"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233601","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":"2035 – LIPOYLATION PATHWAY DEPENDENCY IN LEUKEMIC STEM CELLS CONFERS VULNERABILITY TO CUPROPTOSIS","authors":"Maxime Sajot, Mélinda Alves, Sarah Mouche, Ambrine Sahal, Jean-Emmanuel Sarry, Sarah Bertoli, Laura Poillet, Margherita Ghisi, François Vergez, Jérôme Tamburini, Carine Joffre, Christian Récher, Clément Larrue","doi":"10.1016/j.exphem.2026.105563","DOIUrl":"10.1016/j.exphem.2026.105563","url":null,"abstract":"<div><div>Acute myeloid leukemia (AML) remains a clinically challenging disease due to therapy resistance and relapse driven by leukemic stem cells (LSCs). Identifying LSC-specific vulnerabilities is essential to improve therapeutic outcomes.</div><div>We performed a high-throughput screen of 3,247 anticancer compounds using a patient-derived xenograft (PDX) sample enriched for CD34<sup>+</sup>CD38<sup>–</sup> cells. We identified two copper ionophores, disulfiram and 8-hydroxyquinoline (8-HQ), as top hits, suggesting marked sensitivity of LSCs to copper overload. Validation in primary AML samples (n = 8) confirmed that disulfiram, 8-HQ, and elesclomol preferentially induced cell death in the CD34<sup>+</sup>CD38<sup>–</sup> compartment.</div><div>Single-cell RNA sequencing (scRNA-seq) of CD34<sup>+</sup>CD38<sup>–</sup> cells revealed that LSC-enriched clusters exhibited elevated cuproptosis-related gene signatures. Consistently, treatment with copper ionophores induced aggregation of dihydrolipoamide S-acetyltransferase (DLAT), hallmarks of cuproptosis.</div><div>We found that LSCs displayed lower intracellular copper levels compared with progenitor cells. Transcriptomic analyses revealed increased expression of copper efflux transporters ATP7A and ATP7B in LSCs. Their silencing impaired clonogenicity and induced mitochondrial dysfunction and cell death. It also reduced leukemic burden in PDX models (n = 3) in both primary and secondary transplants, highlighting a critical role for copper homeostasis in LSC self-renewal.</div><div>Finally, scRNA-seq and western blot analyses demonstrated elevated levels of lipoylated DLAT in the LSC compartment. Inhibition of DLAT or the lipoylation enzyme LIAS reduced clonogenic potential and promoted myeloid differentiation in primary AML samples.</div><div>These findings identify LSC dependence on the lipoylation pathway, creating vulnerability to cuproptosis. Targeting copper homeostasis and lipoylation represents a promising therapeutic strategy in AML.</div></div><div>Acute myeloid leukemia (AML) remains a clinically challenging disease due to therapy resistance and relapse driven by leukemic stem cells (LSCs). Identifying LSC-specific vulnerabilities is essential to improve therapeutic outcomes.</div><div>We performed a high-throughput screen of 3,247 anticancer compounds using a patient-derived xenograft (PDX) sample enriched for CD34<sup>+</sup>CD38<sup>–</sup> cells. We identified two copper ionophores, disulfiram and 8-hydroxyquinoline (8-HQ), as top hits, suggesting marked sensitivity of LSCs to copper overload. Validation in primary AML samples (n = 8) confirmed that disulfiram, 8-HQ, and elesclomol preferentially induced cell death in the CD34<sup>+</sup>CD38<sup>–</sup> compartment.</div><div>Single-cell RNA sequencing (scRNA-seq) of CD34<sup>+</sup>CD38<sup>–</sup> cells revealed that LSC-enriched clusters exhibited elevated cuproptosis-related gene signatures. Consistently, treatment with coppe","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105563"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233752","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":"1004 – ESTABLISHING AND MAINTAINING THE HUMAN HEMATOPOIETIC STEM CELL PROGRAM","authors":"Vincenzo Calvanese","doi":"10.1016/j.exphem.2026.105500","DOIUrl":"10.1016/j.exphem.2026.105500","url":null,"abstract":"<div><div>Hematopoietic stem cells (HSCs) sustain lifelong blood production through self-renewal and multilineage differentiation. Despite their central role in health and disease, the molecular mechanisms that establish and preserve the human HSC program remain poorly understood, limiting our ability to generate or expand HSCs for clinical use.</div><div>Our work has approached this challenge from complementary angles. Previous single-cell mapping of human HSCs from the first trimester to birth had revealed a conserved HSC signature (including myeloid/lymphoid or mixed-lineage leukemia; translocated to, 3/AF9 [MLLT3] and hepatic leukemia factor [HLF]) that tracks their emergence and maturation across developmental niches. Building on this framework, we now addressed two fundamental questions: how the mature HSC program is established during development and how it is maintained.</div><div>Longitudinal single-nucleus multiomic profiling of human fetal HSCs revealed transcriptional and chromatin-level modifications accompanying maturation across developmental stages. Complementary spatial analysis allowed definition of the microenvironmental cues that support this process. Paired analysis of fetal liver and fetal bone marrow HSCs uncovered remodeling of HSC metabolism and lineage priming, together with dynamic niche changes associated with HSC relocation.</div><div>To understand how HSC identity is maintained, we further investigated key regulators within the HSC transcriptional network. Mechanistic studies of MLLT3 established transcriptional pausing and elongation as central to HSC function; tuning these processes through cyclin-dependent kinase 9 (CDK9) inhibition preserves HSC identity in ex viv<em>o</em> expansion and improves long-term engraftment. In addition, isoform-specific dissection of HLF revealed precise chromatin regulation sustaining HSC self-renewal.</div><div>Together, we described a model in which HSC function emerges through the coordinated action of developmental programs, specialized microenvironments, and transcriptional regulatory mechanisms. Defining the molecular grammar of human stemness may ultimately enable the rational generation, expansion, and therapeutic manipulation of HSCs in regenerative medicine and leukemia.</div></div><div>Hematopoietic stem cells (HSCs) sustain lifelong blood production through self-renewal and multilineage differentiation. Despite their central role in health and disease, the molecular mechanisms that establish and preserve the human HSC program remain poorly understood, limiting our ability to generate or expand HSCs for clinical use.</div><div>Our work has approached this challenge from complementary angles. Previous single-cell mapping of human HSCs from the first trimester to birth had revealed a conserved HSC signature (including myeloid/lymphoid or mixed-lineage leukemia; translocated to, 3/AF9 [MLLT3] and hepatic leukemia factor [HLF]) that tracks their emergence and maturation across","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105500"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233759","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":"2006 – CD49F EXPRESSION MARKS MOLECULARLY AND FUNCTIONALLY DISTINCT YOLK SAC AND DEFINITIVE HEMATOPOIETIC MESODERM SUBSETS","authors":"Quynh Nguyen, Vladimir Manchev, Gregory Kent, Donghe Yang, Jamie Kwan, Brenda Cohen, Nicole Zhao, Ian Fernandes, Paraish Misra, Mark Gagliardi, Marion Kennedy, Gordon Keller","doi":"10.1016/j.exphem.2026.105534","DOIUrl":"10.1016/j.exphem.2026.105534","url":null,"abstract":"<div><div>The generation of human pluripotent stem cell (hPSC)-derived hematopoietic progenitors for therapy depends on accurately specifying the correct program in vitro. Developmental biology-guided protocols have enabled the generation of distinct yolk sac (YS) and definitive programs. Recent advances have shown that HSCs can be specified from the definitive program, whereas primitive and multipotent progenitors (MPPs) can arise from the YS program. Despite this, the low frequency of these progenitors remains a major limitation for further characterization and therapeutic use. As hematopoietic fates are specified early during mesoderm induction, the inefficient generation of distinct hematopoietic cell types may reflect failure to properly specify the desired mesoderm subsets. To address this, we identified new markers that resolve heterogeneity within both YS and definitive hematopoietic mesoderm populations. Through temporal analyses and cell isolation studies, we found that CD49F expression identifies distinct YS and definitive mesoderm subsets. Transcriptomic analyses revealed molecular signatures consistent with their developmental origins, and their hematopoietic progeny showed differences indicative of YS and definitive hematopoiesis. Finally, functional assays demonstrated that the CD49F expression marks the subset of YS mesoderm that displays multilineage hematopoietic potential, distinct from primitive hematopoiesis; however, within the definitive program, it identifies a subpopulation of mesoderm that gives rise to multiple hematopoietic lineages including cells able to provide long-term hematopoietic engraftment. Collectively, these findings establish a developmental framework of the human hematopoietic system that enables precise specification of distinct hematopoietic programs and generation of otherwise inaccessible progenitors for future cell therapies.</div></div><div>The generation of human pluripotent stem cell (hPSC)-derived hematopoietic progenitors for therapy depends on accurately specifying the correct program in vitro. Developmental biology-guided protocols have enabled the generation of distinct yolk sac (YS) and definitive programs. Recent advances have shown that HSCs can be specified from the definitive program, whereas primitive and multipotent progenitors (MPPs) can arise from the YS program. Despite this, the low frequency of these progenitors remains a major limitation for further characterization and therapeutic use. As hematopoietic fates are specified early during mesoderm induction, the inefficient generation of distinct hematopoietic cell types may reflect failure to properly specify the desired mesoderm subsets. To address this, we identified new markers that resolve heterogeneity within both YS and definitive hematopoietic mesoderm populations. Through temporal analyses and cell isolation studies, we found that CD49F expression identifies distinct YS and definitive mesoderm subsets. Transcriptomic analys","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105534"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233826","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":"2023 – COORDINATED INTERACTIONS ACROSS BIOLOGICAL SCALES DEFINE DISEASE TRAJECTORIES IN ACUTE MYELOID LEUKEMIA","authors":"Jan Barinka, Sarah Gräßle, Magdalena Pajonk, Rosa Allesøe, Stefanos Bamopoulos, Maximilian Mönnig, Caroline Röthemeier, Lea Jopp-Saile, Dominik Vonficht, Eleni Besiridou, Jana Ihlow, Jan Braune, Evi Vlachou, Sergi Beneyto-Calabuig, Michael Kardorff, Selina Neunhäuser, Vincent Fregona, Simone Feurstein, Adriane Halik, Helen George, Simon Haas","doi":"10.1016/j.exphem.2026.105551","DOIUrl":"10.1016/j.exphem.2026.105551","url":null,"abstract":"<div><div>Acute myeloid leukemia (AML) exhibits extensive heterogeneity across genetic, cellular, and microenvironmental scales, yet how these layers interact to shape disease phenotypes and clinical trajectories remains poorly understood. Here, we present a multiscale single-cell dataset of 184 treatment-naïve AML patients spanning all major genetic subtypes, coupled with detailed immune microenvironment profiling and comprehensive clinical annotation and follow-up. We define ten AML archetypes based on recurrent genotype–phenotype relationships within leukemic stem and progenitor cells, refining established classifications and resolving heterogeneity within NPM1- and myelodysplasia-related AML. To systematically resolve how biological layers profiled at diagnosis interact and shape individual clinical endpoints, we develop an analytical framework based on quantitative modeling. We demonstrate that distinct clinical outcomes arise from specific interactions operating within and across these layers. Response to induction chemotherapy is primarily determined by the interaction between genetic drivers and leukemic differentiation state, captured by AML archetypes. In contrast, relapse following chemotherapy is driven predominantly by nongenetic leukemia-intrinsic programs linked to metabolic state. Relapse after allogeneic stem cell transplantation is shaped mainly by microenvironmental factors and the extent of residual healthy hematopoiesis. Finally, overall survival was determined by a complex interplay of genetic and nongenetic determinants, alongside largely independent effects such as systemic interferon signaling. Together, our study provides a framework to resolve intrapatient and interpatient heterogeneity in AML and supports a unifying model in which distinct clinical outcomes are governed by specific, recurrent patterns of interaction across biological layers.</div></div><div>Acute myeloid leukemia (AML) exhibits extensive heterogeneity across genetic, cellular, and microenvironmental scales, yet how these layers interact to shape disease phenotypes and clinical trajectories remains poorly understood. Here, we present a multiscale single-cell dataset of 184 treatment-naïve AML patients spanning all major genetic subtypes, coupled with detailed immune microenvironment profiling and comprehensive clinical annotation and follow-up. We define ten AML archetypes based on recurrent genotype–phenotype relationships within leukemic stem and progenitor cells, refining established classifications and resolving heterogeneity within NPM1- and myelodysplasia-related AML. To systematically resolve how biological layers profiled at diagnosis interact and shape individual clinical endpoints, we develop an analytical framework based on quantitative modeling. We demonstrate that distinct clinical outcomes arise from specific interactions operating within and across these layers. Response to induction chemotherapy is primarily determined by the interaction","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105551"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234034","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":"3266 – EPIGENETIC FUNCTION OF RNA HELICASE DDX21 IN FETAL HEMATOPOIESIS","authors":"Hoi-Hung Cheung,&nbsp;Adrian On-Wah Leung,&nbsp;Chang Li","doi":"10.1016/j.exphem.2026.105588","DOIUrl":"10.1016/j.exphem.2026.105588","url":null,"abstract":"<div><div>Asp-Glu-Ala-Asp (DEAD)-box RNA helicase DDX21 is a nucleolar protein known for its role in ribosomal RNA (rRNA) transcription and ribosome biogenesis, with emerging functions in pre-rRNA splicing and N6-methyladenosine (m6A) modification. In this study, we demonstrated that fetal hematopoietic stem and progenitor cells (HSPCs) lacking Ddx21 undergo p53-dependent cell cycle arrest, resulting in fetal anemia and pancytopenia. Beyond its canonical role in ribosome biogenesis, Ddx21 regulates key hematopoietic genes such as Gata1 and cKit. Mechanistically, Ddx21 interacts with the H3K4me3 demethylase Kdm5a, forming a chromatin RNA-sensitive complex that co-occupies actively transcribed loci, including recombinant (rDNA), cKit, and Gata1. Loss of Ddx21 reduces Kdm5a-occupied H3K4me3 marks at promoters, leading to transcriptional repression. Importantly, inhibition of Kdm5a and p53 rescues the cell cycle defect, enhances cKit expression, and restores colony-forming capacity. Together, these findings revealed that DDX21 collaborates with KDM5A to maintain HSPC self-renewal through an epigenetic mechanism. This work highlighted DDX21 as a critical hematopoietic factor linking ribosome biogenesis to epigenetic control of hematopoiesis, with implications for understanding fetal blood development and potential therapeutic strategies.</div></div><div>Asp-Glu-Ala-Asp (DEAD)-box RNA helicase DDX21 is a nucleolar protein known for its role in ribosomal RNA (rRNA) transcription and ribosome biogenesis, with emerging functions in pre-rRNA splicing and N6-methyladenosine (m6A) modification. In this study, we demonstrated that fetal hematopoietic stem and progenitor cells (HSPCs) lacking Ddx21 undergo p53-dependent cell cycle arrest, resulting in fetal anemia and pancytopenia. Beyond its canonical role in ribosome biogenesis, Ddx21 regulates key hematopoietic genes such as Gata1 and cKit. Mechanistically, Ddx21 interacts with the H3K4me3 demethylase Kdm5a, forming a chromatin RNA-sensitive complex that co-occupies actively transcribed loci, including recombinant (rDNA), cKit, and Gata1. Loss of Ddx21 reduces Kdm5a-occupied H3K4me3 marks at promoters, leading to transcriptional repression. Importantly, inhibition of Kdm5a and p53 rescues the cell cycle defect, enhances cKit expression, and restores colony-forming capacity. Together, these findings revealed that DDX21 collaborates with KDM5A to maintain HSPC self-renewal through an epigenetic mechanism. This work highlighted DDX21 as a critical hematopoietic factor linking ribosome biogenesis to epigenetic control of hematopoiesis, with implications for understanding fetal blood development and potential therapeutic strategies.</div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105588"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234042","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":"2046 – RESTRAINT OF TGFB/BMP SIGNALING IS NECESSARY FOR THE MATURATION OF HEMATOPOIETIC STEM CELLS IN THE MOUSE EMBRYO","authors":"Laura Bennett,&nbsp;Wenbao Yu,&nbsp;Hyun Hyung An,&nbsp;Kai Tan,&nbsp;Nancy Speck","doi":"10.1016/j.exphem.2026.105574","DOIUrl":"10.1016/j.exphem.2026.105574","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Hematopoietic stem cells (HSCs), defined as cells that can engraft an adult when transplanted, mature from precursors (pre-HSCs) that differentiate from hemogenic endothelial cells (HECs) in aorta-gonad-mesonephros (AGM) region of the embryo. Many signaling pathways required to generate the first hematopoietic stem and progenitor cells in the embryo are well characterized, but how HSCs mature from pre-HSCs is poorly understood. Here, we show that mothers against decapentaplegic homolog 7 (SMAD7), a negative regulator of transforming growth factor beta (TGFβ) and bone morphogenetic protein (BMP) signaling is required for pre-HSC to HSC maturation. Deletion of Smad7 in endothelial cells results in a complete loss of functional adult-repopulating HSCs at embryonic day (E) 11.5 when there is an estimated 1 HSC/embryo equivalent. Limiting dilution transplants of E12.5 AGMs showed an 85% reduction in the number of adult-repopulating HSCs in Smad7 KO embryos. Loss of SMAD7 did not impact the formation of HSC independent progenitors, such as lympho-myeloid progenitors (LMPs) in the AGM or erythro-myeloid progenitors (EMPs) in the yolk sac. Single-cell RNA-seq showed formation of pre-HSCs from HECs was unaffected by loss of SMAD7. However, ex vivo maturation of SMAD7 KO pre-HSCs showed a similar 85% reduction in the maturation frequency compared with wild-type controls. Treating pre-HSCs with a BMP inhibitor during ex vivo maturation rescued the HSC maturation defect. A similar rescue of HSC maturation was not observed treating with a TGFβ inhibitor. The data indicate that although TGFβ and BMP signaling are required for the generation of HECs and for HECs to undergo an endothelial-to-hematopoietic transition to generate pre-HSCs, BMP signaling specifically must be subsequently downregulated for effective pre-HSC to HSC maturation.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Hematopoietic stem cells (HSCs), defined as cells that can engraft an adult when transplanted, mature from precursors (pre-HSCs) that differentiate from hemogenic endothelial cells (HECs) in aorta-gonad-mesonephros (AGM) region of the embryo. Many signaling pathways required to generate the first hematopoietic stem and progenitor cells in the embryo are well characterized, but how HSCs mature from pre-HSCs is poorly understood. Here, we show that mothers against decapentaplegic homolog 7 (SMAD7), a negative regulator of transforming growth factor beta (TGFβ) and bone morphogenetic protein (BMP) signaling is required for pre-HSC to HSC maturation. Deletion of Smad7 in endothelial cells results in a complete loss of functional adult-repopulating HSCs at embryonic day (E) 11.5 when there is an estimated 1 HSC/embryo equivalent. Limiting dilution transplants of E12.5 AGMs showed an 85% reduction in the number of adult-repopulating HSCs in Smad7 KO embryos. Loss of SMAD7 did not impact the formation of HSC independent progenitors, such as lympho-myeloid progenitors (LMPs) in the AGM or erythro-myeloid proge","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105574"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234051","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":"3265 – STRUCTURAL IDENTIFICATION OF MAJOR MOLECULAR DETERMINANTS FOR PHOSPHOTYROSINE RECOGNITION IN TYROSINE KINASES REVEALS TUMOR PROMOTING AND SUPPRESSIVE FUNCTIONS","authors":"Nuo Cheng,&nbsp;Siân Evans,&nbsp;Cécile Lopez,&nbsp;George Giotopoulos,&nbsp;Luis Millán-Barea,&nbsp;Marc Creixell,&nbsp;Alexis Barr,&nbsp;Yi Wen Kong,&nbsp;Brian Joughin,&nbsp;Jette Lengefeld,&nbsp;James Clarke,&nbsp;Chuan Liu,&nbsp;Ganapathy Sriram,&nbsp;Tania González-Robles,&nbsp;Bert van de Kooij,&nbsp;Simonas Savickas,&nbsp;Erwin Schoof,&nbsp;Jared Johnson,&nbsp;Chris Bakal,&nbsp;Lewis Cantley,&nbsp;Pau Creixell","doi":"10.1016/j.exphem.2026.105587","DOIUrl":"10.1016/j.exphem.2026.105587","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Breakpoint cluster region-Abelson (BCR-ABL)+ leukemia is a prototypical kinase-driven malignancy in which tyrosine kinase inhibitors have improved outcomes, yet resistant chronic myeloid leukemia (CML), blast-phase CML, and Philadelphia+ acute lymphoblastic leukemia remain major therapeutic challenges. Current BCR-ABL inhibitors suppress BCR-ABL signaling globally, without distinguishing substrates that promote leukemia from those that may restrain disease progression.&lt;/div&gt;&lt;div&gt;Protein tyrosine kinases phosphorylate tyrosine residues in their substrates, an activity hijacked in leukemia to sustain oncogenic signaling. We recently found that, beyond conventional phosphotyrosine (pTyr)-dependent signaling through phosphobinding modules, Abl and several other kinases can directly recognize a pTyr adjacent to the phospho-acceptor tyrosine, thereby generating twin pTyr-pTyr sites.&lt;/div&gt;&lt;div&gt;Using structure-guided protein engineering and substrate-specificity profiling, we created Abl variants with graded pTyr-recognition activity and disrupted phosphoprimed recognition without abolishing kinase function. In BCR-ABL-driven mouse leukemia models, hypomorphic loss-of-function variants showed slower disease progression, whereas neomorphic phosphopriming-deficient variants drove faster and more aggressive myeloproliferative disease. Contrary to current dogma, these findings suggest that a subset of phosphoprimed twin pTyr-pTyr substrates downstream of BCR-ABL suppresses leukemogenesis in vivo.&lt;/div&gt;&lt;div&gt;Together, our data revealed a previously unappreciated leukemia-suppressive signaling layer downstream of BCR-ABL and suggest that twin pTyr-pTyr signaling diversifies oncogenic kinase outputs in hematologic malignancies. This distinction may inform more precise therapeutic strategies that target disease-promoting BCR-ABL signaling while preserving, or exploiting, disease-restraining pathways.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Breakpoint cluster region-Abelson (BCR-ABL)+ leukemia is a prototypical kinase-driven malignancy in which tyrosine kinase inhibitors have improved outcomes, yet resistant chronic myeloid leukemia (CML), blast-phase CML, and Philadelphia+ acute lymphoblastic leukemia remain major therapeutic challenges. Current BCR-ABL inhibitors suppress BCR-ABL signaling globally, without distinguishing substrates that promote leukemia from those that may restrain disease progression.&lt;/div&gt;&lt;div&gt;Protein tyrosine kinases phosphorylate tyrosine residues in their substrates, an activity hijacked in leukemia to sustain oncogenic signaling. We recently found that, beyond conventional phosphotyrosine (pTyr)-dependent signaling through phosphobinding modules, Abl and several other kinases can directly recognize a pTyr adjacent to the phospho-acceptor tyrosine, thereby generating twin pTyr-pTyr sites.&lt;/div&gt;&lt;div&gt;Using structure-guided protein engineering and substrate-specificity profiling, we created Abl variants with graded pTyr-recognition activity and disrupted p","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105587"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234055","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":"2049 – LOSS-OF-FUNCTION DNMT3A MUTATION LEADS TO ABERRANT NEUTROPHIL MIGRATION","authors":"Frieda Zimmer,&nbsp;Daniel Kennedy,&nbsp;Spencer Redding,&nbsp;Ruoqiong Cao,&nbsp;Sarah Waldvogel,&nbsp;Apoorva Thatavarty,&nbsp;Bryan Bahoua,&nbsp;Brandon Tran,&nbsp;Arushana Maknojia,&nbsp;Margaret Goodell,&nbsp;Antony Rodriguez,&nbsp;Katie Matatall,&nbsp;Katherine King","doi":"10.1016/j.exphem.2026.105577","DOIUrl":"10.1016/j.exphem.2026.105577","url":null,"abstract":"<div><div>Clonal hematopoiesis (CH), an age-related expansion of somatically mutated hematopoietic clones, is associated with increased risk of severe infections including COVID-19, yet the underlying mechanisms remain unclear. Here, we investigated the impact of Dnmt3a deficiency in a murine model of influenza A virus (IAV) pneumonia.</div><div>Dnmt3a-deficient mice exhibited increased pulmonary viral burden and reduced neutrophil accumulation in IAV-infected lungs despite comparable circulating neutrophil numbers. Functional analyses of neutrophils showed impaired chemotactic migration in vitro, whereas maturation, antimicrobial enzyme content, and metabolic capacity were unchanged. Transcriptomic profiling revealed downregulation of pathways involved in chemotaxis, cytokine signaling, and cellular activation, including reduced expression of Cxcr1. Supporting the translational relevance of these findings, proteomic analysis of plasma from individuals with germline DNMT3A mutations (Tatton-Brown–Rahman syndrome) revealed alterations in proteins associated with cell migration and cytoskeletal dynamics.</div><div>Collectively, our findings demonstrate that Dnmt3a loss compromises innate immune defense by impairing neutrophil migration in a cell-intrinsic manner, leading to ineffective pathogen clearance. This work provides mechanistic insight into how CH-associated mutations contribute to age-associated susceptibility to infection and highlights altered</div></div><div>Clonal hematopoiesis (CH), an age-related expansion of somatically mutated hematopoietic clones, is associated with increased risk of severe infections including COVID-19, yet the underlying mechanisms remain unclear. Here, we investigated the impact of Dnmt3a deficiency in a murine model of influenza A virus (IAV) pneumonia.</div><div>Dnmt3a-deficient mice exhibited increased pulmonary viral burden and reduced neutrophil accumulation in IAV-infected lungs despite comparable circulating neutrophil numbers. Functional analyses of neutrophils showed impaired chemotactic migration in vitro, whereas maturation, antimicrobial enzyme content, and metabolic capacity were unchanged. Transcriptomic profiling revealed downregulation of pathways involved in chemotaxis, cytokine signaling, and cellular activation, including reduced expression of Cxcr1. Supporting the translational relevance of these findings, proteomic analysis of plasma from individuals with germline DNMT3A mutations (Tatton-Brown–Rahman syndrome) revealed alterations in proteins associated with cell migration and cytoskeletal dynamics.</div><div>Collectively, our findings demonstrate that Dnmt3a loss compromises innate immune defense by impairing neutrophil migration in a cell-intrinsic manner, leading to ineffective pathogen clearance. This work provides mechanistic insight into how CH-associated mutations contribute to age-associated susceptibility to infection and highlights altered</div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105577"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234059","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":"2040 – GASTRULOIDS CAPTURE MULTIWAVE HEMATOPOIESIS WITH SPATIAL AND TEMPORAL ACCURACY","authors":"Susanne C. van den Brink,&nbsp;Ylenia Cicirò,&nbsp;Jesse de Lange,&nbsp;David Blank,&nbsp;Edurne Solabarrieta Larrañaga,&nbsp;Anna Ávila Gálvez,&nbsp;Pau Pascual Mas,&nbsp;Balthazar Perrin,&nbsp;Gabriel Torregrosa-Cortès,&nbsp;André Dias,&nbsp;Marella de Bruijn,&nbsp;Denise Ragusa,&nbsp;Alfonso Martinez Arias,&nbsp;Anna Bigas,&nbsp;Cristina Pina","doi":"10.1016/j.exphem.2026.105568","DOIUrl":"10.1016/j.exphem.2026.105568","url":null,"abstract":"&lt;div&gt;&lt;div&gt;In the embryo, blood progenitors are formed in two sites, the yolk sac (YS) and the aorta-gonad-mesonephros (AGM), as independent waves of blood formation. In recent years, numerous in vitro models have approximated YS and/or AGM hematopoiesis, but none has been able to reconstruct both hematopoietic waves in their niches with spatiotemporal accuracy.&lt;/div&gt;&lt;div&gt;Recently, we described a 3D mouse embryonic stem cell-based hemogenic gastruloid (haemGx) model, which captures multiwave embryonic hematopoiesis in vitro. Here, we characterize this model in detail using single-cell transcriptomics and high-content imaging. Pseudotime analysis of single-cell RNA-seq data captures two independent hematopoietic trajectories: a YS-like erythromyeloid progenitors trajectory expressing embryonic globins; and an AGM-like trajectory linking arterial and hemogenic endothelium to hematopoietic stem/progenitor-like cells (HSPC) with expression of adult globins. Accordingly, we detect two waves of RUNX1 expression by microscopy, which are separate in time and space. The first one colocalizes with YS markers Hnf4a and Ttr and has codetection of embryonic globin Hba-x. This location is later lost, and RUNX1 independently appears in elongated DLL4&lt;sup&gt;+&lt;/sup&gt; Flk1&lt;sup&gt;+&lt;/sup&gt; arterial-like vessels, in the medial region of hemogenic gastruloids near mesonephros markers Osr1 and Lhx1, suggestive of an AGM-like location. Importantly, haemGx spontaneously express signals relevant to hematopoiesis, including Bmp4 and Shh, with temporal and spatial congruence to their respective in vivo YS &amp; AGM niches.&lt;/div&gt;&lt;div&gt;In conclusion, we show that our mouse haemGx embryo model faithfully captures YS and AGM hematopoiesis with spatiotemporal accuracy and niche recapitulation. HaemGx can be used for systematic, throughput analyses of developmental hematopoiesis in vitro, paving the way to bona fide HSPC production for clinical applications.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;In the embryo, blood progenitors are formed in two sites, the yolk sac (YS) and the aorta-gonad-mesonephros (AGM), as independent waves of blood formation. In recent years, numerous in vitro models have approximated YS and/or AGM hematopoiesis, but none has been able to reconstruct both hematopoietic waves in their niches with spatiotemporal accuracy.&lt;/div&gt;&lt;div&gt;Recently, we described a 3D mouse embryonic stem cell-based hemogenic gastruloid (haemGx) model, which captures multiwave embryonic hematopoiesis in vitro. Here, we characterize this model in detail using single-cell transcriptomics and high-content imaging. Pseudotime analysis of single-cell RNA-seq data captures two independent hematopoietic trajectories: a YS-like erythromyeloid progenitors trajectory expressing embryonic globins; and an AGM-like trajectory linking arterial and hemogenic endothelium to hematopoietic stem/progenitor-like cells (HSPC) with expression of adult globins. Accordingly, we detect two waves of RUNX1 expression by microscopy, which ar","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105568"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234113","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}