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
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
Studying embryonic hematopoiesis is complicated by diversity of its locations in the constantly changing anatomy and by the mobility of blood cell precursors.Embryonic hematopoietic progenitors are identified in tradi...Studying embryonic hematopoiesis is complicated by diversity of its locations in the constantly changing anatomy and by the mobility of blood cell precursors.Embryonic hematopoietic progenitors are identified in traditional in vivo and in vitro cell potential assays.Profound epigenetic plasticity of mammalian embryonic cells combined with significant inductive capacity of the potential assays suggest that our understanding of hematopoietic ontogenesis is substantially distorted.Non-invasive in vivo cell tracing methodology offers a better insight into complex processes of blood cell specification.In contrast to the widely accepted view based on the cell potential assays,the genetic tracing approach identified the yolk sac as the source of adult hematopoietic stem cell lineage.Realistic knowledge of the blood origin is critical for safe and efficient recapitulation of hematopoietic development in culture.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 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.
文摘Studying embryonic hematopoiesis is complicated by diversity of its locations in the constantly changing anatomy and by the mobility of blood cell precursors.Embryonic hematopoietic progenitors are identified in traditional in vivo and in vitro cell potential assays.Profound epigenetic plasticity of mammalian embryonic cells combined with significant inductive capacity of the potential assays suggest that our understanding of hematopoietic ontogenesis is substantially distorted.Non-invasive in vivo cell tracing methodology offers a better insight into complex processes of blood cell specification.In contrast to the widely accepted view based on the cell potential assays,the genetic tracing approach identified the yolk sac as the source of adult hematopoietic stem cell lineage.Realistic knowledge of the blood origin is critical for safe and efficient recapitulation of hematopoietic development in culture.
