Transcriptional Diversity during Lineage Commitment of Human Blood Progenitors The authors characterized gene expression programs driving lineage choice, they sequenced RNA from eight primary human hematopoietic progenitor populations representing the major myeloid commitment stages and the main lymphoid stage. [Science] Abstract | Press Release SIRT1 Activation by a c-MYC Oncogenic Network Promotes the Maintenance and Drug Resistance of Human FLT3-ITD Acute Myeloid Leukemia Stem Cells Investigators show that the NAD-dependent SIRT1 deacetylase is selectively overexpressed in primary human FLT3-ITD acute myeloid leukemia stem cells. This SIRT1 overexpression is related to enhanced expression of the USP22 deubiquitinase induced by c-MYC, leading to reduced SIRT1 ubiquitination and enhanced stability. [Cell Stem Cell] Full Article | Graphical Abstract TNF-Mediated Inflammation Represses GATA1 and Activates p38 MAP Kinase in RPS19 Deficient Hematopoietic Progenitors Scientists found that RPS19 deficiency in hematopoietic progenitor cells leads to decreased GATA1 expression in the erythroid progenitor population and p53-dependent upregulation of TNF-α in non-erythroid cells. [Blood] Abstract Growth Hormone Receptor Signaling Is Dispensable for HSC Function and Aging Repeat challenge with 5-fluorouracil showed that growth hormone receptor (Ghr) was dispensable for hematopoietic stem cell (HSC) activation and homeostatic recovery in vivo and, following challenge, Ghr-deficient HSCs functioned normally through serial transplantation. [Blood] Abstract Identification of a Dynamic Core Transcriptional Network in t(8;21) AML that Regulates Differentiation Block and Self-Renewal Researchers used digital footprinting and chromatin immunoprecipitation sequencing to identify the core RUNX1/ETO-responsive transcriptional network of t(8;21) cells. They show that the transcriptional program underlying leukemic propagation is regulated by a dynamic equilibrium between RUNX1/ETO and RUNX1 complexes, which bind to identical DNA sites in a mutually exclusive fashion. [Cell Rep] Full Article | Graphical Abstract The Orphan Nuclear Receptor NR4A1 Specifies a Distinct Subpopulation of Quiescent Myeloid-Biased Long-Term HSCs Investigators show that NR4A1 is most highly expressed in a subset of Lin–Sca-1+c-Kit+ CD48–CD150+ long-term hematopoietic stem cells (HSCs), and its expression is tightly associated with HSC quiescence. They also demonstrate that NR4A1 expression in HSCs is induced by PGE2, a known enhancer of stem cell engraftment potential. [Stem Cells] Abstract Simultaneous Deletion of p21Cip1/Waf1 and Caspase-3 Accelerates Proliferation and Partially Rescues the Differentiation Defects of Caspase-3 Deficient Hematopoietic Stem Cells Depletion of both Caspase-3 and p21Cip1/Waf1 resulted in an more pronounced increase in the frequency of hematopoietic stem and progenitor cells. [PLoS One] Full Article CLINICAL RESEARCH CD45RA Depletion in HLA-Mismatched Allogeneic Hematopoietic Stem Cell Transplantation for Primary Combined Immunodeficiency: A Preliminary Study Five consecutive patients with combined immunodeficiencies and chronic viral infections underwent an allogeneic, HLA-mismatched hematopoietic stem cell transplantation. Investigators analyzed whether the selective depletion of naive T cells from allografts might constitute a way of reducing alloreactivity while maintaining memory T-cell responsiveness to pathogens. [J Allergy Clin Immunol] Abstract Impact of Donor Age on Outcome after Allogeneic Hematopoietic Cell Transplantation The authors studied the impact of donor age on the tempo of hematopoietic engraftment and donor chimerism, acute and chronic graft-vs.-host disease, and non-relapse mortality among 1,174 consecutive patients undergoing myeloablative and 367 patients undergoing non-myeloablative hematopoietic cell transplantation from HLA-matched related or unrelated donors with G-CSF-mobilized peripheral blood mononuclear cell allografts. [Biol Blood Marrow Transplant] Abstract |