Prior to the generation of hematopoietic stem cells(HSCs)from the hemogenic endothelial cells(HECs)mainly in the dorsal aorta in midgestational mouse embryos,multiple hematopoietic progenitors including erythro-myeloi...Prior to the generation of hematopoietic stem cells(HSCs)from the hemogenic endothelial cells(HECs)mainly in the dorsal aorta in midgestational mouse embryos,multiple hematopoietic progenitors including erythro-myeloid progenitors and lymphoid progenitors are generated from yolk sac HECs.These HSCindependent hematopoietic progenitors have recently been identified as major contributors to functional blood cell production until birth.However,little is known about yolk sac HECs.Here,combining integrative analyses of multiple single-cell RNA-sequencing datasets and functional assays,we reveal that Neurl3-EGFP,in addition to marking the continuum throughout the ontogeny of HSCs from HECs,can also serve as a single enrichment marker for yolk sac HECs.Moreover,while yolk sac HECs have much weaker arterial characteristics than either arterial endothelial cells in the yolk sac or HECs within the embryo proper,the lymphoid potential of yolk sac HECs is largely confined to the arterial-biased subpopulation featured by the Unc5b expression.Interestingly,the B lymphoid potential of hematopoietic progenitors,but not for myeloid potentials,is exclusively detected in Neurl3-negative subpopulations in midgestational embryos.Taken together,these findings enhance our understanding of blood birth from yolk sac HECs and provide theoretical basis and candidate reporters for monitoring step-wise hematopoietic differentiation.展开更多
Hematopoietic stem cells(HSCs) are specified and generated during the embryonic development and have remarkable potential to replenish the full set of blood cell lineages. Researchers have long been interested in clar...Hematopoietic stem cells(HSCs) are specified and generated during the embryonic development and have remarkable potential to replenish the full set of blood cell lineages. Researchers have long been interested in clarifying the molecular events involved in HSC specification. Many studies have reported the development of methods for generating functional hematopoietic cells from pluripotent stem cells(PSCs-embryonic stem cells(ESCs) and induced pluripotent stem cells(i PSCs)) for decades. However, the generation of HSCs with robust long-term repopulation potential remains a swingeing challenge, of which a major factor contributing to this failure is the difficulty to define the intraembryonic signals related to the specification of HSCs. Since HSCs directly derive from hemogenic endothelium, in this review, we summarize both in vivo and in vitro studies on conserved signaling pathways that control the specification of HSCs from hemogenic endothelial cells.展开更多
The yolk sac drives vertebrate embryonic hematopoiesis through primitive hematopoiesis and endothelial-to-hematopoietic transition(EHT)waves.However,dynamic cellular and molecular changes during EHT of the yolk sac re...The yolk sac drives vertebrate embryonic hematopoiesis through primitive hematopoiesis and endothelial-to-hematopoietic transition(EHT)waves.However,dynamic cellular and molecular changes during EHT of the yolk sac remain to be elucidated.We built a comprehensive atlas of early endothelial and hematopoietic development in the yolk sac by integrating single-cell transcriptomic data from mouse embryos(E6.75-E11.0).Focusing on the yolk sac(E7.5-E9.5),we established a refined atlas capturing key cell populations of EHT in the yolk sac.This enabled the identification of distinct hemogenic endothelial cell(HEC)subpopulations and revealed 2 fundamentally distinct waves of yolk sac hemogenesis via EHT that differed in temporal emergence,cellular origin,molecular signature,and lineage bias.The first EHT wave,emerging around E8.0,originated from primordial endothelial cells and exhibited a bias toward the generation of erythromyeloid progenitors.In contrast,the second EHT wave,emerging around E8.5,originated from maturing yolk sac endothelial cells,expressed key intraembryonic HEC markers(Hlf,Nupr1,Gfi1),and showed a hematopoietic stem and progenitor cell fate bias.Furthermore,molecular dynamics analysis of the pseudo-trajectory during the 2 waves of EHT in mouse yolk sacs revealed different dynamic changes in several pathways,particularly the ribosome and metabolic pathways.The yolk sac endothelial and hematopoietic atlas is accessible from an interactive web server(https://lllab.shinyapps.io/ysshinyapp/).Collectively,this study provides novel insights into the multi-wave nature of yolk sac hematopoiesis,clarifies the fundamental principles of yolk sac EHT at a single-cell resolution,and offers potential guidance for in vitro blood cell regeneration strategies.展开更多
During embryogenesis,hematopoietic stem progenitor cells(HSPCs)are believed to be derived from hemogenic endothelial cells(HECs).Moreover,arterial feature is proposed to be a prerequisite for HECs to generate HSPCs wi...During embryogenesis,hematopoietic stem progenitor cells(HSPCs)are believed to be derived from hemogenic endothelial cells(HECs).Moreover,arterial feature is proposed to be a prerequisite for HECs to generate HSPCs with lymphoid potential.Although the molecular basis of hematopoietic stem cell-competent HECs has been delicately elucidated within the embryo proper,the functional and molecular characteristics of HECs in the extraembryonic yolk sac(YS)remain largely unresolved.In this study,we initially identified six molecularly different endothelial populations in the midgestational YS through integrated analysis of several single-cell RNA sequencing(scRNA-seq)datasets and validated the arterial vasculature distribution of Gja5+ECs using a Gja5-EGFP reporter mouse model.Further,we explored the hemogenic potential of different EC populations based on their Gja5-EGFP and CD44 expression levels.The hemogenic potential was ubiquitously detected in spatiotemporally different vascular beds on embryonic days(E)8.5–E9.5 and gradually concentrated in CD44-positive ECs from E10.0.Unexpectedly,B-lymphoid potential was detected in the YS ECs as early as E8.5 regardless of their arterial features.Furthermore,the capacity for generating hematopoietic progenitors with in vivo lymphoid potential was found in nonarterial as well as arterial YS ECs on E10.0–E10.5.Importantly,the distinct identities of E10.0–E10.5 HECs between YS and intraembryonic caudal region were revealed by further scRNA-seq analysis.Cumulatively,these findings extend our knowledge regarding the hemogenic potential of ECs from anatomically and molecularly different vascular beds,providing a theoretical basis for better understanding the sources of HSPCs during mammalian development.展开更多
RUNXI is absolutely required for definitive hematopoiesis, but the function of RUNXlb/c, two isoforms of human RUNX1, is unclear. We established inducible RUNXlb/c-overexpressing human embryonic stem cell （hESC） lin...RUNXI is absolutely required for definitive hematopoiesis, but the function of RUNXlb/c, two isoforms of human RUNX1, is unclear. We established inducible RUNXlb/c-overexpressing human embryonic stem cell （hESC） lines, in which RUNXlb/c overexpression prevented the emergence of CD34＋ cells from early stage, thereby drastically reducing the production of hematopoi- etic stem/prognnitor cells. Simultaneously, the expression of hematopoiesis-related factors was downregulated. However, such blockage effect disappeared from day 6 in hESC/AGM-S3 ceU co-cultures, proving that the blockage occurred before the generation of hemogenic endothelial cells. This blockage was partially rescued by RepSox, an inhibitor of the transforming growth factor （TGF）-β signaling pathway, indicating a close relationship between RUNX1b/c and TGF-β pathway. Our results suggest a unique inhibitory function of RUNX1b/c in the development of early hematopoiesis and may aid further understanding of its biological function in normal and diseased models.展开更多
Hematopoietic stem progenitor cells(HSPCs)are derived from a specialized subset of endothelial cells named hemogenic endothelial cells(HECs)via a process of endothelial-to-hematopoietic transition during embryogenesis...Hematopoietic stem progenitor cells(HSPCs)are derived from a specialized subset of endothelial cells named hemogenic endothelial cells(HECs)via a process of endothelial-to-hematopoietic transition during embryogenesis.Recently,with the usage of multiple single-cell technologies and advanced genetic lineage tracing techniques,namely,“TIF”approaches that combining transcriptome,immunophenotype and function/fate analyses,massive new insights have been achieved regarding the cellular and molecular evolution underlying the emergence of HSPCs from embryonic vascular beds.In this review,we focus on the most recent advances in the enrichment markers,functional characteristics,developmental paths,molecular controls,and the embryonic site-relevance of the key intermediate cell populations bridging embryonic vascular and hematopoietic systems,namely HECs and pre-hematopoietic stem cells,the immediate progenies of some HECs,in mouse and human embryos.Specifically,using expression analyses at both transcriptional and protein levels and especially efficient functional assays,we propose that the onset of Kit expression is at the HEC stage,which has previously been controversial.展开更多
基金supported by the National Key R&D Program of China(2022YFA1103501,2020YFA0112400,2021YFA1100102)the National Natural Science Foundation of China(82000111,81890991,31930054,82200121,82122004,82270118)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2017ZT07S347).
文摘Prior to the generation of hematopoietic stem cells(HSCs)from the hemogenic endothelial cells(HECs)mainly in the dorsal aorta in midgestational mouse embryos,multiple hematopoietic progenitors including erythro-myeloid progenitors and lymphoid progenitors are generated from yolk sac HECs.These HSCindependent hematopoietic progenitors have recently been identified as major contributors to functional blood cell production until birth.However,little is known about yolk sac HECs.Here,combining integrative analyses of multiple single-cell RNA-sequencing datasets and functional assays,we reveal that Neurl3-EGFP,in addition to marking the continuum throughout the ontogeny of HSCs from HECs,can also serve as a single enrichment marker for yolk sac HECs.Moreover,while yolk sac HECs have much weaker arterial characteristics than either arterial endothelial cells in the yolk sac or HECs within the embryo proper,the lymphoid potential of yolk sac HECs is largely confined to the arterial-biased subpopulation featured by the Unc5b expression.Interestingly,the B lymphoid potential of hematopoietic progenitors,but not for myeloid potentials,is exclusively detected in Neurl3-negative subpopulations in midgestational embryos.Taken together,these findings enhance our understanding of blood birth from yolk sac HECs and provide theoretical basis and candidate reporters for monitoring step-wise hematopoietic differentiation.
基金supported by the National Key Basic Research Program of China(2015CB964903)the National Natural Science Foundation of China(81270640)
文摘Hematopoietic stem cells(HSCs) are specified and generated during the embryonic development and have remarkable potential to replenish the full set of blood cell lineages. Researchers have long been interested in clarifying the molecular events involved in HSC specification. Many studies have reported the development of methods for generating functional hematopoietic cells from pluripotent stem cells(PSCs-embryonic stem cells(ESCs) and induced pluripotent stem cells(i PSCs)) for decades. However, the generation of HSCs with robust long-term repopulation potential remains a swingeing challenge, of which a major factor contributing to this failure is the difficulty to define the intraembryonic signals related to the specification of HSCs. Since HSCs directly derive from hemogenic endothelium, in this review, we summarize both in vivo and in vitro studies on conserved signaling pathways that control the specification of HSCs from hemogenic endothelial cells.
基金supported by grants from the National Key R&D Program of China(2021YFA1100901,2022YFA1103501,2024YFA1108301,and 2022YFA1105700)the National Natural Science Foundation of China(82270118,82470115,and 82330006)CAMS Innovation Fund for Medical Sciences(2023-I2M-2-007).
文摘The yolk sac drives vertebrate embryonic hematopoiesis through primitive hematopoiesis and endothelial-to-hematopoietic transition(EHT)waves.However,dynamic cellular and molecular changes during EHT of the yolk sac remain to be elucidated.We built a comprehensive atlas of early endothelial and hematopoietic development in the yolk sac by integrating single-cell transcriptomic data from mouse embryos(E6.75-E11.0).Focusing on the yolk sac(E7.5-E9.5),we established a refined atlas capturing key cell populations of EHT in the yolk sac.This enabled the identification of distinct hemogenic endothelial cell(HEC)subpopulations and revealed 2 fundamentally distinct waves of yolk sac hemogenesis via EHT that differed in temporal emergence,cellular origin,molecular signature,and lineage bias.The first EHT wave,emerging around E8.0,originated from primordial endothelial cells and exhibited a bias toward the generation of erythromyeloid progenitors.In contrast,the second EHT wave,emerging around E8.5,originated from maturing yolk sac endothelial cells,expressed key intraembryonic HEC markers(Hlf,Nupr1,Gfi1),and showed a hematopoietic stem and progenitor cell fate bias.Furthermore,molecular dynamics analysis of the pseudo-trajectory during the 2 waves of EHT in mouse yolk sacs revealed different dynamic changes in several pathways,particularly the ribosome and metabolic pathways.The yolk sac endothelial and hematopoietic atlas is accessible from an interactive web server(https://lllab.shinyapps.io/ysshinyapp/).Collectively,this study provides novel insights into the multi-wave nature of yolk sac hematopoiesis,clarifies the fundamental principles of yolk sac EHT at a single-cell resolution,and offers potential guidance for in vitro blood cell regeneration strategies.
基金supported by the National Key Research and Development Program of China(2020YFA0112402,2017YFA0103401,and 2016YFA0100601)the National Natural Science Foundation of China(81890991,31930054,31871173,82000111,and 81900115)+1 种基金the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(2017ZT07S347)the Key Research and Development Program of Guangdong Province(2019B020234002)。
文摘During embryogenesis,hematopoietic stem progenitor cells(HSPCs)are believed to be derived from hemogenic endothelial cells(HECs).Moreover,arterial feature is proposed to be a prerequisite for HECs to generate HSPCs with lymphoid potential.Although the molecular basis of hematopoietic stem cell-competent HECs has been delicately elucidated within the embryo proper,the functional and molecular characteristics of HECs in the extraembryonic yolk sac(YS)remain largely unresolved.In this study,we initially identified six molecularly different endothelial populations in the midgestational YS through integrated analysis of several single-cell RNA sequencing(scRNA-seq)datasets and validated the arterial vasculature distribution of Gja5+ECs using a Gja5-EGFP reporter mouse model.Further,we explored the hemogenic potential of different EC populations based on their Gja5-EGFP and CD44 expression levels.The hemogenic potential was ubiquitously detected in spatiotemporally different vascular beds on embryonic days(E)8.5–E9.5 and gradually concentrated in CD44-positive ECs from E10.0.Unexpectedly,B-lymphoid potential was detected in the YS ECs as early as E8.5 regardless of their arterial features.Furthermore,the capacity for generating hematopoietic progenitors with in vivo lymphoid potential was found in nonarterial as well as arterial YS ECs on E10.0–E10.5.Importantly,the distinct identities of E10.0–E10.5 HECs between YS and intraembryonic caudal region were revealed by further scRNA-seq analysis.Cumulatively,these findings extend our knowledge regarding the hemogenic potential of ECs from anatomically and molecularly different vascular beds,providing a theoretical basis for better understanding the sources of HSPCs during mammalian development.
基金This work was supported by the National Program on Key Basic Research Project of China （973 Program 2015CB964902）, the National Natural Science Foundation of China （NSFC H81170466 and H81370597）, and the CAMS Initiatives for Innovative Medicine （2016-12M-1-018） awarded to F.M.
文摘RUNXI is absolutely required for definitive hematopoiesis, but the function of RUNXlb/c, two isoforms of human RUNX1, is unclear. We established inducible RUNXlb/c-overexpressing human embryonic stem cell （hESC） lines, in which RUNXlb/c overexpression prevented the emergence of CD34＋ cells from early stage, thereby drastically reducing the production of hematopoi- etic stem/prognnitor cells. Simultaneously, the expression of hematopoiesis-related factors was downregulated. However, such blockage effect disappeared from day 6 in hESC/AGM-S3 ceU co-cultures, proving that the blockage occurred before the generation of hemogenic endothelial cells. This blockage was partially rescued by RepSox, an inhibitor of the transforming growth factor （TGF）-β signaling pathway, indicating a close relationship between RUNX1b/c and TGF-β pathway. Our results suggest a unique inhibitory function of RUNX1b/c in the development of early hematopoiesis and may aid further understanding of its biological function in normal and diseased models.
基金supported by the National Key R&D Program of China(2022YFA110350 and 2020YFA0112400)State Key Laboratory of Experimental Hematology Research Grant(ZK23-04)the National Natural Science Foundation of China(82000111).
文摘Hematopoietic stem progenitor cells(HSPCs)are derived from a specialized subset of endothelial cells named hemogenic endothelial cells(HECs)via a process of endothelial-to-hematopoietic transition during embryogenesis.Recently,with the usage of multiple single-cell technologies and advanced genetic lineage tracing techniques,namely,“TIF”approaches that combining transcriptome,immunophenotype and function/fate analyses,massive new insights have been achieved regarding the cellular and molecular evolution underlying the emergence of HSPCs from embryonic vascular beds.In this review,we focus on the most recent advances in the enrichment markers,functional characteristics,developmental paths,molecular controls,and the embryonic site-relevance of the key intermediate cell populations bridging embryonic vascular and hematopoietic systems,namely HECs and pre-hematopoietic stem cells,the immediate progenies of some HECs,in mouse and human embryos.Specifically,using expression analyses at both transcriptional and protein levels and especially efficient functional assays,we propose that the onset of Kit expression is at the HEC stage,which has previously been controversial.
