Pub Date : 2025-11-19DOI: 10.1016/j.exphem.2025.105326
Kavita Bisht, Valérie Barbier, Svetlana Shatunova, Ingrid G. Winkler, Jean-Pierre Lévesque
Stem cell antigen-1 (SCA1) is widely used to identify mouse hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) among lineage-negative KIT+ (LK) cells. However, SCA1 is expressed only in a few inbred mouse strains and becomes strongly upregulated in LK cells following in vivo challenge with interferons, lipopolysaccharide (LPS), or pathogens, leading to incorrect analysis of HSC functional subsets and delineation of HSC, MPP, and lineage-restricted progenitor phenotypes. Endothelial protein C receptor CD201 can be used as an alternative marker for mouse and even human HSC. However, whether CD201 expression changes following infectious challenge is unknown. Unlike SCA1, CD201 expression did not change on mouse LK cells in response to LPS in vivo. Long-term competitive transplantations with CD201+, CD201−, or SCA1+ LK cells showed that most reconstituting HSCs are within the LK CD201+ population after LPS challenge. However, the long-term competitive repopulation potential of LK SCA1+ cells from LPS-treated mice was much more severely reduced than that of LK CD201+ cells from the same LPS-treated donors, suggesting that the LK SCA1+ population in challenged donors becomes contaminated with CD201− progenitors devoid of long-term repopulation potential. Based on the CD201 gating strategy, we reassessed the effect of LPS on HSC and MPP cycling and mobilization and their dependency on MY88 and TRIF adaptors. In conclusion, CD201 enables a more accurate analysis of mouse HSC and MPP subsets in all inbred strains in septic conditions or steady state.
{"title":"Endothelial protein C receptor CD201 is a better marker than stem cell antigen-1 to identify mouse long-term reconstituting hematopoietic stem cells following septic challenge","authors":"Kavita Bisht, Valérie Barbier, Svetlana Shatunova, Ingrid G. Winkler, Jean-Pierre Lévesque","doi":"10.1016/j.exphem.2025.105326","DOIUrl":"10.1016/j.exphem.2025.105326","url":null,"abstract":"<div><div>Stem cell antigen-1 (SCA1) is widely used to identify mouse hematopoietic stem cells (HSCs) and multipotent progenitors (MPPs) among lineage-negative KIT<sup>+</sup> (LK) cells. However, SCA1 is expressed only in a few inbred mouse strains and becomes strongly upregulated in LK cells following in vivo challenge with interferons, lipopolysaccharide (LPS), or pathogens, leading to incorrect analysis of HSC functional subsets and delineation of HSC, MPP, and lineage-restricted progenitor phenotypes. Endothelial protein C receptor CD201 can be used as an alternative marker for mouse and even human HSC. However, whether CD201 expression changes following infectious challenge is unknown. Unlike SCA1, CD201 expression did not change on mouse LK cells in response to LPS in vivo. Long-term competitive transplantations with CD201<sup>+</sup>, CD201<sup>−</sup>, or SCA1<sup>+</sup> LK cells showed that most reconstituting HSCs are within the LK CD201<sup>+</sup> population after LPS challenge. However, the long-term competitive repopulation potential of LK SCA1<sup>+</sup> cells from LPS-treated mice was much more severely reduced than that of LK CD201<sup>+</sup> cells from the same LPS-treated donors, suggesting that the LK SCA1<sup>+</sup> population in challenged donors becomes contaminated with CD201<sup>−</sup> progenitors devoid of long-term repopulation potential. Based on the CD201 gating strategy, we reassessed the effect of LPS on HSC and MPP cycling and mobilization and their dependency on MY88 and TRIF adaptors. In conclusion, CD201 enables a more accurate analysis of mouse HSC and MPP subsets in all inbred strains in septic conditions or steady state.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"154 ","pages":"Article 105326"},"PeriodicalIF":2.1,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145573449","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}
Pub Date : 2025-11-07DOI: 10.1016/j.exphem.2025.105288
Adela S. Cellucci , Danila B. Yañuk , Paola R. Lev , Ana C. Glembotsky , Nora P. Goette , María C. Lira , Geraldine De Luca , Laureano J. Kamiya , Paula G. Heller , Rosana F. Marta
Cytoreductive treatment is a main strategy to reduce thrombotic complications and ameliorate symptoms in Phi-negative myeloproliferative neoplasms (MPNs) comprising essential thrombocythemia, polycythemia vera, and primary myelofibrosis. Based on the observation of differences in platelet size during microscopic analysis of blood smears from MPN patients, in this work we studied whether these differences could be dependent on the type of cytoreductive drug used for patients’ treatment and whether changes in platelet size could be induced by the effect of these drugs on thrombopoiesis. Maximum platelet diameter (MPD) was measured in 120 patients with MPN. The effect of drugs on thrombopoiesis was evaluated in normal megakaryocytes (MKs) obtained from cord blood–derived CD34+ hematopoietic progenitors. Anagrelide (ANA), α-interferon (IFN), and ruxolitinib (Ruxo) increased, whereas hydroxyurea (HU) decreased platelet size. MK incubation with these drugs revealed that ANA and IFN induced abnormal proplatelet (PP) architecture and affected microtubular structure, but only ANA altered actin organization, whereas neither Ruxo nor HU modified MK cytoskeleton. By bioinformatic analysis, RANTES downregulation was identified as a candidate responsible for ANA-induced abnormalities. RANTES downregulation was confirmed in MK incubated with ANA but not with IFN. Addition of recombinant RANTES reverted ANA-induced cytoskeletal abnormalities. Evaluation of RANTES plasmatic levels and platelet RNA expression in patients with MPN showed RANTES decrease in both samples during ANA treatment, suggesting that in vitro findings could reflect ANA action in vivo. In conclusion, this study demonstrates the influence of cytoreductive drugs on platelet size and reveals their differential mechanisms of action during platelet production.
{"title":"Cytoreductive treatment differentially affects platelet size and cytoskeletal megakaryocyte organization during thrombopoiesis in myeloproliferative neoplasms","authors":"Adela S. Cellucci , Danila B. Yañuk , Paola R. Lev , Ana C. Glembotsky , Nora P. Goette , María C. Lira , Geraldine De Luca , Laureano J. Kamiya , Paula G. Heller , Rosana F. Marta","doi":"10.1016/j.exphem.2025.105288","DOIUrl":"10.1016/j.exphem.2025.105288","url":null,"abstract":"<div><div>Cytoreductive treatment is a main strategy to reduce thrombotic complications and ameliorate symptoms in Phi-negative myeloproliferative neoplasms (MPNs) comprising essential thrombocythemia, polycythemia vera, and primary myelofibrosis. Based on the observation of differences in platelet size during microscopic analysis of blood smears from MPN patients, in this work we studied whether these differences could be dependent on the type of cytoreductive drug used for patients’ treatment and whether changes in platelet size could be induced by the effect of these drugs on thrombopoiesis. Maximum platelet diameter (MPD) was measured in 120 patients with MPN. The effect of drugs on thrombopoiesis was evaluated in normal megakaryocytes (MKs) obtained from cord blood–derived CD34+ hematopoietic progenitors. Anagrelide (ANA), α-interferon (IFN), and ruxolitinib (Ruxo) increased, whereas hydroxyurea (HU) decreased platelet size. MK incubation with these drugs revealed that ANA and IFN induced abnormal proplatelet (PP) architecture and affected microtubular structure, but only ANA altered actin organization, whereas neither Ruxo nor HU modified MK cytoskeleton. By bioinformatic analysis, RANTES downregulation was identified as a candidate responsible for ANA-induced abnormalities. RANTES downregulation was confirmed in MK incubated with ANA but not with IFN. Addition of recombinant RANTES reverted ANA-induced cytoskeletal abnormalities. Evaluation of RANTES plasmatic levels and platelet RNA expression in patients with MPN showed RANTES decrease in both samples during ANA treatment, suggesting that <em>in vitro</em> findings could reflect ANA action <em>in vivo</em>. In conclusion, this study demonstrates the influence of cytoreductive drugs on platelet size and reveals their differential mechanisms of action during platelet production.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"153 ","pages":"Article 105288"},"PeriodicalIF":2.1,"publicationDate":"2025-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145476589","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}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104924
Norika Liu , Atsushi Nakano
The cells that comprise the circulatory system not only share developmental origins but also mutually support each other’s differentiation during early embryogenesis. Although classical models attribute embryonic hematopoiesis in mammals to the yolk sac and aorta-gonad-mesonephros (AGM) region, we and others have identified the embryonic heart as a transient hematopoietic niche. A subset of endocardial cells in the outflow tract and atrioventricular canal undergo endothelial-to-hematopoietic transition (EHT) in an Nkx2-5-dependent manner, mirroring the tinman-regulated cardio-hematopoietic program in Drosophila. These hemogenic endocardial cells, enriched in the cushion region—the primordia of cardiac valves and septa—not only contribute to local hematopoiesis but also give rise to tissue macrophages that facilitate valve morphogenesis.
These findings challenge the traditional view of hematopoietic compartmentalization and establish a novel paradigm in which the heart itself contributes to hematopoietic development. Using lineage tracing and knockout mouse models, we further show that endocardial-derived macrophages persist into adulthood as tissue-resident macrophages, particularly within cardiac valves and vasculature. Functionally, these cells appear to modulate tissue homeostasis and suppress pathological fibrosis.
In summary, our study reveals that the embryonic heart acts as a local hematopoietic organ, supplying a distinct macrophage population that contributes to both cardiac morphogenesis and long-term homeostasis. These insights broaden our understanding of the interplay between hematopoiesis and cardiogenesis and suggest new avenues for investigating tissue-resident immune cell ontogeny.
{"title":"2011 – THE EMBRYONIC HEART AS A TRANSIENT HEMATOPOIETIC SITE FOR MACROPHAGE-MEDIATED CARDIAC REMODELING","authors":"Norika Liu , Atsushi Nakano","doi":"10.1016/j.exphem.2025.104924","DOIUrl":"10.1016/j.exphem.2025.104924","url":null,"abstract":"<div><div>The cells that comprise the circulatory system not only share developmental origins but also mutually support each other’s differentiation during early embryogenesis. Although classical models attribute embryonic hematopoiesis in mammals to the yolk sac and aorta-gonad-mesonephros (AGM) region, we and others have identified the embryonic heart as a transient hematopoietic niche. A subset of endocardial cells in the outflow tract and atrioventricular canal undergo endothelial-to-hematopoietic transition (EHT) in an Nkx2-5-dependent manner, mirroring the tinman-regulated cardio-hematopoietic program in Drosophila. These hemogenic endocardial cells, enriched in the cushion region—the primordia of cardiac valves and septa—not only contribute to local hematopoiesis but also give rise to tissue macrophages that facilitate valve morphogenesis.</div><div>These findings challenge the traditional view of hematopoietic compartmentalization and establish a novel paradigm in which the heart itself contributes to hematopoietic development. Using lineage tracing and knockout mouse models, we further show that endocardial-derived macrophages persist into adulthood as tissue-resident macrophages, particularly within cardiac valves and vasculature. Functionally, these cells appear to modulate tissue homeostasis and suppress pathological fibrosis.</div><div>In summary, our study reveals that the embryonic heart acts as a local hematopoietic organ, supplying a distinct macrophage population that contributes to both cardiac morphogenesis and long-term homeostasis. These insights broaden our understanding of the interplay between hematopoiesis and cardiogenesis and suggest new avenues for investigating tissue-resident immune cell ontogeny.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104924"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620047","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}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104930
Alexandra Preston , Joe Frost , Megan Teh , Mohsin Badat , Andrew Armitage , Ruggiero Norfo , Sarah Wideman , Muhammad Hanifi , Natasha White , Noemi Roy , Christian Babbs , Bart Ghesquiere , James Davies , Andrew Howden , Linda Sinclair , Jim Hughes , Mira Kassouf , Robert Beagrie , Douglas Higgs , Hal Drakesmith
α-globin’s genomic next-door neighbor, Nprl3, contains 4 of the 5 α-globin enhancers. Nprl3 negatively regulates mTORC1, a master controller of cell metabolism. Nprl3, α-globin, and the α-globin enhancers have been colocated for >500 million years. However, the function of this genomic linkage is unknown.
Using a mouse in which the Nprl3 promoter is deleted (with no effect on the α-globin enhancers), we showed that Nprl3 is required for optimal erythropoiesis in fetal liver and bone marrow. On embryonic day 13.5 (E13.5) in the fetal liver, Nprl3−/− erythroid cells failed to develop beyond the proerythroblast stage. Metabolite profiling, RNA-Seq and proteomics showed that Nprl3−/− erythroblasts have overactivated mTORC1 signaling, overcharged glycolysis, and suppressed autophagy. Competitive bone marrow-fetal liver chimeras indicated a hematopoietic-intrinsic Nprl3 requirement for erythropoiesis. To study human erythropoiesis, we induced NPRL3-knockout by RNP-editing primary CD34+ cells. Edited progenitors produced fewer enucleated erythroid cells and exhibited defective mTORC1 signaling responses to fluctuating iron, amino acid, and erythropoietin (EPO) availability. Nprl3 tunes the metabolism of developing erythroid cells to their nutritional environment.
Nprl3 expression is highly elevated in erythroid cells. We showed that this is due to the interaction between the Nprl3 promoter and α-globin enhancers. We eliminated interactions (in cis) between Nprl3 and the enhancers, while maintaining enhancer control of α-globin. Remarkably, our approach resulted in erythropoietic impairment reminiscent of the Nprl3−/− genotype (with E13.5 erythroid development inhibited at the same stage of differentiation). Therefore, the ancient transcriptional hub of Nprl3, α-globin, and their enhancers supports the erythroid-specific upregulation of Nprl3 and coordinates metabolic control with red blood cell development.
{"title":"2017 – ANCIENT GENOMIC LINKAGE OF NPRL3 AND Α-GLOBIN COUPLES METABOLISM WITH ERYTHROID DEVELOPMENT","authors":"Alexandra Preston , Joe Frost , Megan Teh , Mohsin Badat , Andrew Armitage , Ruggiero Norfo , Sarah Wideman , Muhammad Hanifi , Natasha White , Noemi Roy , Christian Babbs , Bart Ghesquiere , James Davies , Andrew Howden , Linda Sinclair , Jim Hughes , Mira Kassouf , Robert Beagrie , Douglas Higgs , Hal Drakesmith","doi":"10.1016/j.exphem.2025.104930","DOIUrl":"10.1016/j.exphem.2025.104930","url":null,"abstract":"<div><div>α-globin’s genomic next-door neighbor, Nprl3, contains 4 of the 5 α-globin enhancers. Nprl3 negatively regulates mTORC1, a master controller of cell metabolism. Nprl3, α-globin, and the α-globin enhancers have been colocated for >500 million years. However, the function of this genomic linkage is unknown.</div><div>Using a mouse in which the Nprl3 promoter is deleted (with no effect on the α-globin enhancers), we showed that Nprl3 is required for optimal erythropoiesis in fetal liver and bone marrow. On embryonic day 13.5 (E13.5) in the fetal liver, Nprl3−/− erythroid cells failed to develop beyond the proerythroblast stage. Metabolite profiling, RNA-Seq and proteomics showed that Nprl3−/− erythroblasts have overactivated mTORC1 signaling, overcharged glycolysis, and suppressed autophagy. Competitive bone marrow-fetal liver chimeras indicated a hematopoietic-intrinsic Nprl3 requirement for erythropoiesis. To study human erythropoiesis, we induced NPRL3-knockout by RNP-editing primary CD34+ cells. Edited progenitors produced fewer enucleated erythroid cells and exhibited defective mTORC1 signaling responses to fluctuating iron, amino acid, and erythropoietin (EPO) availability. Nprl3 tunes the metabolism of developing erythroid cells to their nutritional environment.</div><div>Nprl3 expression is highly elevated in erythroid cells. We showed that this is due to the interaction between the Nprl3 promoter and α-globin enhancers. We eliminated interactions (in cis) between Nprl3 and the enhancers, while maintaining enhancer control of α-globin. Remarkably, our approach resulted in erythropoietic impairment reminiscent of the Nprl3−/− genotype (with E13.5 erythroid development inhibited at the same stage of differentiation). Therefore, the ancient transcriptional hub of Nprl3, α-globin, and their enhancers supports the erythroid-specific upregulation of Nprl3 and coordinates metabolic control with red blood cell development.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104930"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620065","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}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104928
Lev Kats , Emily Gruber , Sree Kumar , Rheana Franich , Omer Gilan , Tiffany Khong , Andrew Spencer
Multiple myeloma (MM) is a common plasma cell malignancy that remains mostly incurable. We analyzed the Cancer Gene Dependency Map and identified menin as a therapeutically actionable MM vulnerability. Gene knockout and menin inhibitor (iMenin) therapy experiments across an extensive panel of MM cell lines confirmed that ∼20% are highly sensitive to menin disruption, with an additional ∼40% demonstrating a partial response. Similar findings were also made in a separate custom panel of early passage MM lines that more closely recapitulate genetic alterations found in patients with MM.
Gene expression and chromatin profiling studies in iMenin-sensitive, intermediate, and refractory MM lines identified the master myeloma cell identity factor IRF4 as the major downstream target of menin inhibition. iMenin-sensitive lines are characterized by abundant deposition of the menin/MLL1 complex at the super-enhancer of IRF4, with iMenin treatment resulting in eviction of menin/MLL1 from chromatin and concomitant suppression of IRF4 and its target genes. Interestingly, iMenin sensitivity in MM also correlates with transcriptional signatures of immature B cells that are, in turn, inversely correlated with response to many current treatments, especially those that target the B-cell maturation antigen (BCMA).
In parallel, we also applied genome-wide CRISPR screening, which implicated the CREBBP/EP300/NCOR1 axis as a key modulator of iMenin sensitivity. Notably, clinical-grade menin and EP300 inhibitors demonstrated synergistic activity against primary patients with MM samples cultured ex vivo and against the syngeneic Vk*MYC MM model in vivo. Molecular analysis revealed deep and synergistic suppression of IRF4 potentiated by the combination. Altogether, our comprehensive study identified menin as a promising target in MM and charts potential paths for rapid clinical translation.
{"title":"2015 – MENIN ORCHESTRATES EXPRESSION OF THE MASTER PLASMA CELL TRANSCRIPTION FACTOR IRF4 AND IS AN ACTIONABLE TARGET IN MULTIPLE MYELOMA.","authors":"Lev Kats , Emily Gruber , Sree Kumar , Rheana Franich , Omer Gilan , Tiffany Khong , Andrew Spencer","doi":"10.1016/j.exphem.2025.104928","DOIUrl":"10.1016/j.exphem.2025.104928","url":null,"abstract":"<div><div>Multiple myeloma (MM) is a common plasma cell malignancy that remains mostly incurable. We analyzed the Cancer Gene Dependency Map and identified menin as a therapeutically actionable MM vulnerability. Gene knockout and menin inhibitor (iMenin) therapy experiments across an extensive panel of MM cell lines confirmed that ∼20% are highly sensitive to menin disruption, with an additional ∼40% demonstrating a partial response. Similar findings were also made in a separate custom panel of early passage MM lines that more closely recapitulate genetic alterations found in patients with MM.</div><div>Gene expression and chromatin profiling studies in iMenin-sensitive, intermediate, and refractory MM lines identified the master myeloma cell identity factor IRF4 as the major downstream target of menin inhibition. iMenin-sensitive lines are characterized by abundant deposition of the menin/MLL1 complex at the super-enhancer of IRF4, with iMenin treatment resulting in eviction of menin/MLL1 from chromatin and concomitant suppression of IRF4 and its target genes. Interestingly, iMenin sensitivity in MM also correlates with transcriptional signatures of immature B cells that are, in turn, inversely correlated with response to many current treatments, especially those that target the B-cell maturation antigen (BCMA).</div><div>In parallel, we also applied genome-wide CRISPR screening, which implicated the CREBBP/EP300/NCOR1 axis as a key modulator of iMenin sensitivity. Notably, clinical-grade menin and EP300 inhibitors demonstrated synergistic activity against primary patients with MM samples cultured ex vivo and against the syngeneic Vk*MYC MM model in vivo. Molecular analysis revealed deep and synergistic suppression of IRF4 potentiated by the combination. Altogether, our comprehensive study identified menin as a promising target in MM and charts potential paths for rapid clinical translation.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104928"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620058","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}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104922
Zining Yang, Hui Cheng, Tao Cheng, Can Li, Jingxuan Li, Ruixia Sun
The developmental transition from early embryonic hematopoiesis to adult bone marrow hematopoiesis is a complex process that remains poorly understood. In particular, the cellular composition and regulatory mechanisms of the microenvironment during the initial engraftment and establishment of hematopoietic stem cells (HSCs) in the bone marrow are unclear. Understanding these niche components is essential to reveal how hematopoiesis develops and adapts.
In this study, we identify a previously unrecognized population of mature mast cells transiently present across multiple hematopoietic organs—including liver, spleen, and bone marrow—during early bone marrow hematopoiesis in both humans and mice.
These mast cells display distinct molecular markers and mature granule morphology, indicating their functional activity. Using in vitro coculture experiments, we show that mast cells directly support HSC function through the secretion of serotonin (5-HT). Depletion of mast cells during the perinatal period leads to significantly reduced 5-HT levels in the spleen and a marked decrease in hematopoietic stem and progenitor cell (HSPC) numbers. This reveals a critical role for mast cell-derived serotonin in regulating early hematopoiesis. We also provide transcriptomic profiles of mast cells from neonatal mouse hematopoietic tissues, expanding the cross-tissue transcriptomic atlas of mouse mast cells and revealing specialized gene expression signatures linked to their developmental function.
Together, these findings have revealed the new role of mast cells in supporting hematopoiesis during specific developmental windows, highlighting their significance as microenvironment regulators in the early hematopoietic development of both humans and mice.
{"title":"2009 – MAST CELLS SUPPORT HEMATOPOIETIC STEM CELL FUNCTION DURING THE TRANSITION TO BONE MARROW HEMATOPOIESIS","authors":"Zining Yang, Hui Cheng, Tao Cheng, Can Li, Jingxuan Li, Ruixia Sun","doi":"10.1016/j.exphem.2025.104922","DOIUrl":"10.1016/j.exphem.2025.104922","url":null,"abstract":"<div><div>The developmental transition from early embryonic hematopoiesis to adult bone marrow hematopoiesis is a complex process that remains poorly understood. In particular, the cellular composition and regulatory mechanisms of the microenvironment during the initial engraftment and establishment of hematopoietic stem cells (HSCs) in the bone marrow are unclear. Understanding these niche components is essential to reveal how hematopoiesis develops and adapts.</div><div>In this study, we identify a previously unrecognized population of mature mast cells transiently present across multiple hematopoietic organs—including liver, spleen, and bone marrow—during early bone marrow hematopoiesis in both humans and mice.</div><div>These mast cells display distinct molecular markers and mature granule morphology, indicating their functional activity. Using in vitro coculture experiments, we show that mast cells directly support HSC function through the secretion of serotonin (5-HT). Depletion of mast cells during the perinatal period leads to significantly reduced 5-HT levels in the spleen and a marked decrease in hematopoietic stem and progenitor cell (HSPC) numbers. This reveals a critical role for mast cell-derived serotonin in regulating early hematopoiesis. We also provide transcriptomic profiles of mast cells from neonatal mouse hematopoietic tissues, expanding the cross-tissue transcriptomic atlas of mouse mast cells and revealing specialized gene expression signatures linked to their developmental function.</div><div>Together, these findings have revealed the new role of mast cells in supporting hematopoiesis during specific developmental windows, highlighting their significance as microenvironment regulators in the early hematopoietic development of both humans and mice.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104922"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620171","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}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104906
Florian Perner
The mixed lineage leukemia (KMT2A/MLL1) gene is critical for hematopoiesis, but its translocation drives aggressive, treatment-resistant leukemias in infants and adults. Although previous targeted strategies showed limited efficacy, the recent development of menin inhibitors, disrupting the KMT2A-menin interaction, demonstrated significant promise. However, therapeutic resistance to these menin inhibitors emerges rapidly under monotherapy, highlighting a critical challenge and the need for deeper molecular understanding to guide intervention. A critical distinction between this class of compounds and conventional chemotherapeutic agents or apoptosis-inducing drugs like venetoclax lies in their mechanism of action. Unlike these agents, which typically trigger rapid cell death, menin inhibitors do not induce immediate cytotoxicity. Instead, they alleviate the differentiation blockade by reprogramming aberrant oncogenic chromatin states. As a result, the time to achieve the best clinical response is prolonged, with leukemia cells persisting for weeks to months in both preclinical models and early-phase clinical trials. During this extended period of persistence, leukemia cells undergo a complex adaptive process, transitioning into a drug-tolerant persister state that enables them to withstand therapeutic pressure. Interestingly, the molecular signatures of these persister cells closely resemble those observed in drug-tolerant cancer cells across other tumor types, suggesting a conserved mechanism of cellular plasticity that transcends cancer subtypes and treatment modalities. In leukemia, this adaptive state is characterized by cellular dormancy and the emergence of transcriptional and immunophenotypic features indicative of myeloid differentiation. These findings underscore a significant clinical challenge: in this context, defining the tipping point between a cell retaining leukemogenic potential and a terminally differentiated cell in diagnostic assays becomes difficult, if not impossible. This ambiguity highlights the need for more precise biomarkers to monitor therapeutic responses and predict clinical outcomes in patients treated with menin inhibitors.
{"title":"1026 – CELLULAR PLASTICITY DRIVES PERSISTENCE AND RESISTANCE OF LEUKEMIA CELLS UNDER MENIN INHIBITOR TREATMENT","authors":"Florian Perner","doi":"10.1016/j.exphem.2025.104906","DOIUrl":"10.1016/j.exphem.2025.104906","url":null,"abstract":"<div><div>The mixed lineage leukemia (KMT2A/MLL1) gene is critical for hematopoiesis, but its translocation drives aggressive, treatment-resistant leukemias in infants and adults. Although previous targeted strategies showed limited efficacy, the recent development of menin inhibitors, disrupting the KMT2A-menin interaction, demonstrated significant promise. However, therapeutic resistance to these menin inhibitors emerges rapidly under monotherapy, highlighting a critical challenge and the need for deeper molecular understanding to guide intervention. A critical distinction between this class of compounds and conventional chemotherapeutic agents or apoptosis-inducing drugs like venetoclax lies in their mechanism of action. Unlike these agents, which typically trigger rapid cell death, menin inhibitors do not induce immediate cytotoxicity. Instead, they alleviate the differentiation blockade by reprogramming aberrant oncogenic chromatin states. As a result, the time to achieve the best clinical response is prolonged, with leukemia cells persisting for weeks to months in both preclinical models and early-phase clinical trials. During this extended period of persistence, leukemia cells undergo a complex adaptive process, transitioning into a drug-tolerant persister state that enables them to withstand therapeutic pressure. Interestingly, the molecular signatures of these persister cells closely resemble those observed in drug-tolerant cancer cells across other tumor types, suggesting a conserved mechanism of cellular plasticity that transcends cancer subtypes and treatment modalities. In leukemia, this adaptive state is characterized by cellular dormancy and the emergence of transcriptional and immunophenotypic features indicative of myeloid differentiation. These findings underscore a significant clinical challenge: in this context, defining the tipping point between a cell retaining leukemogenic potential and a terminally differentiated cell in diagnostic assays becomes difficult, if not impossible. This ambiguity highlights the need for more precise biomarkers to monitor therapeutic responses and predict clinical outcomes in patients treated with menin inhibitors.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104906"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620269","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}
Pub Date : 2025-11-01DOI: 10.1016/j.exphem.2025.104974
Ryo Yamamoto
Self-renewal and differentiation are inherent properties of hematopoietic stem cells (HSCs) that are necessary to support hematopoiesis; however, the underlying mechanisms, especially in humans, remain unclear. Here, using the cynomolgus macaque as a surrogate model, we develop a new gating strategy to isolate with high purity transplantable cynomolgus HSCs and generate a single-cell transcriptomic map of cynomolgus HSCs and progenitor cells—covering gestational periods previously not analyzed in humans.
We performed single-cell transcriptomic analysis using 10 × genomics and Smart-seq technologies. This study presents a single-cell transcriptomic analysis of CD34hi hematopoietic stem and progenitor cells (HSPCs) from cynomolgus monkeys across developmental stages—fetal liver, fetal bone marrow, and adult bone marrow. We found that there are dynamic shifts in HSPC composition with development: HSC/MPP frequencies peak in late second trimester and decrease with age, whereas myeloid and lymphoid progenitors increase and erythroid/megakaryocyte lineages decline. Developmental and tissue-specific gene expression differences were identified in HSCs, such as higher mitochondrial activity in fetal HSCs and NF-κB–related genes in aged ABM-HSCs. Furthermore, novel surface markers for transcriptionally purified HSCs were identified, offering improved tools for future HSC isolation. We anticipate that our comprehensive data set will serve as a basis for building an HSC atlas of cynomolgus monkeys that will facilitate a better understanding of conserved and nonconserved properties as well as mechanisms between nonhuman primates (NHPs) and humans, which will be necessary for better translational applications in the future.
{"title":"3033 – ATLAS OF CYNOMOLGUS MACAQUE HEMATOPOIESIS","authors":"Ryo Yamamoto","doi":"10.1016/j.exphem.2025.104974","DOIUrl":"10.1016/j.exphem.2025.104974","url":null,"abstract":"<div><div>Self-renewal and differentiation are inherent properties of hematopoietic stem cells (HSCs) that are necessary to support hematopoiesis; however, the underlying mechanisms, especially in humans, remain unclear. Here, using the cynomolgus macaque as a surrogate model, we develop a new gating strategy to isolate with high purity transplantable cynomolgus HSCs and generate a single-cell transcriptomic map of cynomolgus HSCs and progenitor cells—covering gestational periods previously not analyzed in humans.</div><div>We performed single-cell transcriptomic analysis using 10 × genomics and Smart-seq technologies. This study presents a single-cell transcriptomic analysis of CD34hi hematopoietic stem and progenitor cells (HSPCs) from cynomolgus monkeys across developmental stages—fetal liver, fetal bone marrow, and adult bone marrow. We found that there are dynamic shifts in HSPC composition with development: HSC/MPP frequencies peak in late second trimester and decrease with age, whereas myeloid and lymphoid progenitors increase and erythroid/megakaryocyte lineages decline. Developmental and tissue-specific gene expression differences were identified in HSCs, such as higher mitochondrial activity in fetal HSCs and NF-κB–related genes in aged ABM-HSCs. Furthermore, novel surface markers for transcriptionally purified HSCs were identified, offering improved tools for future HSC isolation. We anticipate that our comprehensive data set will serve as a basis for building an HSC atlas of cynomolgus monkeys that will facilitate a better understanding of conserved and nonconserved properties as well as mechanisms between nonhuman primates (NHPs) and humans, which will be necessary for better translational applications in the future.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104974"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620398","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}
During embryogenesis, hematopoietic stem cells (HSCs) arise from hemogenic endothelial cells (HECs). HECs enter endothelial-to-hematopoietic transition (EHT) and differentiate into HSCs via pre-HSCs. Previously, we reported that two cytokines and feeder cells were sufficient to induce HSCs from HECs and pre-HSCs isolated from mouse embryos at embryonic day 10.5 (E10.5). However, the signaling requirements at earlier developmental stages remain largely undefined. In this study, we sought to identify the key signaling factors required to induce HSCs from E9.5 HECs in vitro. Transcriptomic profiling of E9.5 mouse embryos detected activation of bone morphogenetic protein (BMP) signaling in HECs. BMP4 treatment in the culture system enhanced the generation of multilineage hematopoietic colonies and long-term repopulating HSCs, as confirmed using colony-forming and transplantation assays. Furthermore, early-stage HECs capable of forming HSCs expressed the BMP4 receptor. These results suggest that BMP4 plays a key role in promoting the emergence of transplantable HSCs from early HECs and provides insight into stage-specific requirements for HSC development. These findings may contribute to establishing conditions for in vitro derivation of HSCs from pluripotent stem cells.
{"title":"3034 – IN VITRO INDUCTION OF HEMATOPOIETIC STEM CELLS FROM EARLY HEMOGENIC ENDOTHELIAL CELLS","authors":"Mariko Tsuruda , Saori Morino-Koga , Xueyu Zhao , Shingo Usuki , Kei-ichiro Yasunaga , Tomomasa Yokomizo , Ryuichi Nishinakamura , Toshio Suda , Minetaro Ogawa","doi":"10.1016/j.exphem.2025.104975","DOIUrl":"10.1016/j.exphem.2025.104975","url":null,"abstract":"<div><div>During embryogenesis, hematopoietic stem cells (HSCs) arise from hemogenic endothelial cells (HECs). HECs enter endothelial-to-hematopoietic transition (EHT) and differentiate into HSCs via pre-HSCs. Previously, we reported that two cytokines and feeder cells were sufficient to induce HSCs from HECs and pre-HSCs isolated from mouse embryos at embryonic day 10.5 (E10.5). However, the signaling requirements at earlier developmental stages remain largely undefined. In this study, we sought to identify the key signaling factors required to induce HSCs from E9.5 HECs in vitro. Transcriptomic profiling of E9.5 mouse embryos detected activation of bone morphogenetic protein (BMP) signaling in HECs. BMP4 treatment in the culture system enhanced the generation of multilineage hematopoietic colonies and long-term repopulating HSCs, as confirmed using colony-forming and transplantation assays. Furthermore, early-stage HECs capable of forming HSCs expressed the BMP4 receptor. These results suggest that BMP4 plays a key role in promoting the emergence of transplantable HSCs from early HECs and provides insight into stage-specific requirements for HSC development. These findings may contribute to establishing conditions for in vitro derivation of HSCs from pluripotent stem cells.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104975"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620399","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}
Emergence of definitive hematopoietic stem cells (HSCs) during embryonic development is underpinned by the crucial process of endothelial-to-hematopoietic transition (EHT). Therein, HSCs and progenitors are specified from a specialized subset of endothelial cells termed hemogenic endothelium (HE). These cells reside in the aorta-gonad-mesonephros (AGM) region, namely in the ventral wall of the dorsal aorta, and acquire hematopoietic potential through an incompletely characterized morphogenetic and transcriptional programming process that generates the first self-renewing, multilineage HSCs.
We made use of our previously described mouse embryonic stem cell-based 3D hemogenic gastruloid (haemGx) to dissect the dynamic specification of HE and decipher the morpho-molecular reconfiguration that underpins EHT. The haemGx model recapitulates temporally accurate emergence of CD31+CD34+Kit+ cells with HE characteristics, followed by sequential waves of CD41+ and CD45+ cells, corresponding to hematopoietic progenitors.
We integrated high-content microscopy, flow cytometry, and scRNA-seq, coupled to gene regulatory network analysis, to comprehensively capture the transcriptional dynamics of EHT and model HSCs’ emergence in silico. We further dissected intrinsic and extrinsic contributions to EHT and hematopoietic specification by establishing a novel endothelial culture system derived from haemGx and exploring endothelial and hematopoietic formation with different cellular compositions.
Our integrated approach provides a mechanistically tractable model of HE specification and EHT. Comprehensive inference of the dynamic rules underpinning the earliest events in hematopoietic specification will be pivotal to the design of high-efficiency protocols for in vitro production of HSCs.
{"title":"3035 – HEMOGENIC GASTRULOIDS CAPTURE DYNAMIC SPECIFICATION OF HE AND EHT AND INFORM RULES OF HSCS FORMATION","authors":"Ylenia Cicirò , Denise Ragusa , Ayona Johns , Camilla Cerutti , Cristina Pina","doi":"10.1016/j.exphem.2025.104976","DOIUrl":"10.1016/j.exphem.2025.104976","url":null,"abstract":"<div><div>Emergence of definitive hematopoietic stem cells (HSCs) during embryonic development is underpinned by the crucial process of endothelial-to-hematopoietic transition (EHT). Therein, HSCs and progenitors are specified from a specialized subset of endothelial cells termed hemogenic endothelium (HE). These cells reside in the aorta-gonad-mesonephros (AGM) region, namely in the ventral wall of the dorsal aorta, and acquire hematopoietic potential through an incompletely characterized morphogenetic and transcriptional programming process that generates the first self-renewing, multilineage HSCs.</div><div>We made use of our previously described mouse embryonic stem cell-based 3D hemogenic gastruloid (haemGx) to dissect the dynamic specification of HE and decipher the morpho-molecular reconfiguration that underpins EHT. The haemGx model recapitulates temporally accurate emergence of CD31+CD34+Kit+ cells with HE characteristics, followed by sequential waves of CD41+ and CD45+ cells, corresponding to hematopoietic progenitors.</div><div>We integrated high-content microscopy, flow cytometry, and scRNA-seq, coupled to gene regulatory network analysis, to comprehensively capture the transcriptional dynamics of EHT and model HSCs’ emergence in silico. We further dissected intrinsic and extrinsic contributions to EHT and hematopoietic specification by establishing a novel endothelial culture system derived from haemGx and exploring endothelial and hematopoietic formation with different cellular compositions.</div><div>Our integrated approach provides a mechanistically tractable model of HE specification and EHT. Comprehensive inference of the dynamic rules underpinning the earliest events in hematopoietic specification will be pivotal to the design of high-efficiency protocols for in vitro production of HSCs.</div></div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"151 ","pages":"Article 104976"},"PeriodicalIF":2.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620400","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}
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