Studies of adult human hematopoiesis have until now relied on the expression of CD10 to define lymphoid commitment. We report a novel lymphoid-primed population in human bone marrow that is generated from hematopoietic stem cells (HSC) prior to the onset of CD10 expression and B cell commitment, and is identified by high levels of the homing molecule L-selectin (CD62L). CD10-CD62Lhi progenitors have full lymphoid (B/T/NK) potential, and show reduced myeloid and absent erythroid potential. Genome-wide gene expression analysis demonstrates that the CD10-CD62Lhi population represents an intermediate stage of differentiation between CD34+CD38- HSC and CD34+lin-CD10+ progenitors marked by down-regulation of TAL1 and MPL, upregulation of E2A, CD3E and IL2RG expression, and absent B cell commitment or RAG1/2 expression. Immature CD34+CD1a- thymocytes are also CD62Lhi and L-selectin ligands are expressed at the cortico-medullary junction, suggesting a possible role for L-selectin in human thymic homing. These studies identify the earliest stage of lymphoid priming in human bone marrow.
Lymphoid priming in human bone marrow begins before expression of CD10 with upregulation of L-selectin.
Specimen part
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GPI-80 defines self-renewal ability in hematopoietic stem cells during human development.
Specimen part
View SamplesAdvances in pluripotent stem cell and reprogramming technologies have given hope of generating hematopoietic stem cells (HSC) in culture. To succeed, greater understanding of the self-renewing HSC during human development is required. We discovered that glycophosphatidylinositol-anchored surface protein GPI-80 (Vanin 2) defines a distinct subpopulation of human fetal hematopoietic stem/progenitor cells (HSPC) with self-renewal ability. CD34+CD90+CD38-GPI-80+ HSPC were the sole population that maintained proliferative potential and undifferentiated state in bone marrow stroma co-culture, and engrafted in immunodeficient mice. GPI-80 expression also enabled tracking of HSC migration between human fetal hematopoietic niches. The most highly enriched surface protein in GPI-80+ HSPC as compared to their progeny was Integrin alpha-M (ITGAM), which in leukocytes cooperates with GPI-80 to support migration. Knockdown of either GPI-80 or ITGAM was sufficient to perturb undifferentiated HSPC in stroma co-culture. These findings indicate that human fetal HSC utilize common mechanisms with leukocytes for cell-cell interactions governing HSC self-renewal.
GPI-80 defines self-renewal ability in hematopoietic stem cells during human development.
Specimen part
View SamplesAdvances in pluripotent stem cell and reprogramming technologies have given hope of generating hematopoietic stem cells (HSC) in culture. To succeed, greater understanding of the self-renewing HSC during human development is required. We discovered that glycophosphatidylinositol-anchored surface protein GPI-80 (Vanin 2) defines a distinct subpopulation of human fetal hematopoietic stem/progenitor cells (HSPC) with self-renewal ability. CD34+CD90+CD38-GPI-80+ HSPC were the sole population that maintained proliferative potential and undifferentiated state in bone marrow stroma co-culture, and engrafted in immunodeficient mice. GPI-80 expression also enabled tracking of HSC migration between human fetal hematopoietic niches. The most highly enriched surface protein in GPI-80+ HSPC as compared to their progeny was Integrin alpha-M (ITGAM), which in leukocytes cooperates with GPI-80 to support migration. Knockdown of either GPI-80 or ITGAM was sufficient to perturb undifferentiated HSPC in stroma co-culture. These findings indicate that human fetal HSC utilize common mechanisms with leukocytes for cell-cell interactions governing HSC self-renewal.
GPI-80 defines self-renewal ability in hematopoietic stem cells during human development.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Human fetal hemoglobin expression is regulated by the developmental stage-specific repressor BCL11A.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability.
Specimen part, Cell line
View SamplesOne of the long-standing goals in the field has been to establish a culture system that would allow maintenance of HSC properties ex vivo. In the absence of such system, the ability to model human hematopoiesis in vitro has been limited, and there has been little progress in the expansion of human HSCs for clinical application. To that end, we defined a mesenchyml stem cell co-culture system for expansion of clonally multipotent human HSPCs that are protected from apoptosis and immediate differentiation, and retain the HSPC phenotype. By performing a genome-wide gene expression analysis of purified HSPCs isolated at different stages of co-culture, we asked at the molecular level, to what degree hematopetic stem cell properties can be preserved during culture. This temporal gene expression data from in vivo derived- and ex vivo expanded human HSPCs will serve as a resource to identify novel regulatory pathways that control HSC properties, and to develop clinically applicable protocols for HSC expansion.
Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability.
Specimen part
View SamplesDifferences in the amount of fetal hemoglobin (HbF) that persists into adulthood affect the severity of sickle cell disease and the beta-thalassemia syndromes. Genetic association studies have identified sequence variants in the gene BCL11A that influence HbF levels. Here we examine BCL11A as a potential regulator of HbF expression. The high HbF BCL11A genotype is associated with reduced BCL11A expression. Moreover, abundant expression of full-length forms of BCL11A is developmentally restricted to adult erythroid cells. Down-regulation of BCL11A expression in primary adult erythroid cells leads to robust HbF expression. Consistent with a direct role of BCL11A in globin gene regulation, we find that BCL11A occupies several discrete sites in the beta-globin gene cluster. BCL11A emerges as a therapeutic target for reactivation of HbF in beta-hemoglobin disorders.
Human fetal hemoglobin expression is regulated by the developmental stage-specific repressor BCL11A.
No sample metadata fields
View SamplesDifferences in the amount of fetal hemoglobin (HbF) that persists into adulthood affect the severity of sickle cell disease and the beta-thalassemia syndromes. Genetic association studies have identified sequence variants in the gene BCL11A that influence HbF levels. Here we examine BCL11A as a potential regulator of HbF expression. The high HbF BCL11A genotype is associated with reduced BCL11A expression. Moreover, abundant expression of full-length forms of BCL11A is developmentally restricted to adult erythroid cells. Down-regulation of BCL11A expression in primary adult erythroid cells leads to robust HbF expression. Consistent with a direct role of BCL11A in globin gene regulation, we find that BCL11A occupies several discrete sites in the beta-globin gene cluster. BCL11A emerges as a therapeutic target for reactivation of HbF in beta-hemoglobin disorders.
Human fetal hemoglobin expression is regulated by the developmental stage-specific repressor BCL11A.
No sample metadata fields
View SamplesOne of the long-standing goals in the field has been to establish a culture system that would allow maintenance of HSC properties ex vivo. In the absence of such system, the ability to model human hematopoiesis in vitro has been limited, and there has been little progress in the expansion of human HSCs for clinical application. To that end, we defined a mesenchymal stem cell co-culture system based on a monoclonal OP9 stromal cell line (OP9M2), for expansion of clonally multipotent human HSPCs that were protected from apoptosis and immediate differentiation, and retained the HSPC phenotype. To identify the supportive mechanisms, we performed a genome-wide gene expression analysis of OP9M2 stromal cells and compared the expression to a non-supportive stomal line (BFC012). This co-culture system provides a new, well-defined platform for studying mechanisms involved in HSC-niche interactions and protection of critical HSC properties ex vivo.
Expansion on stromal cells preserves the undifferentiated state of human hematopoietic stem cells despite compromised reconstitution ability.
Specimen part, Cell line
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