Distinct Bone Marrow Blood Vessels Differentially Regulate Hematopoiesis Scientists found that mammalian bone marrow stem cell maintenance and leukocyte trafficking are regulated by distinct blood vessel types with different permeability properties. [Nature] Abstract The Public Repository of Xenografts Enables Discovery and Randomized Phase II-Like Trials in Mice Researchers established a large, publicly available repository of well-characterized leukemia and lymphoma patient-derived xenografts that undergo orthotopic engraftment, called the Public Repository of Xenografts. [Cancer Cell] Abstract | Press Release Runx1 Downregulates Stem Cell/Megakaryocytic Transcription Programs that Support Niche Interactions The authors investigated the myeloid progenitor (MP) compartment in Runx1 knockout (KO) mice, arguing that disruptions at the hematopoietic stem and multipotent progenitor cell level may be amplified in downstream cells. They demonstrated that the MP compartment is increased by >5-fold in Runx1 KO mice, with a prominent skewing towards megakaryocyte progenitors. [Blood] Abstract Loss of Ezh2 Cooperates with Jak2V617F in the Development of Myelofibrosis in a Mouse Model of Myeloproliferative Neoplasm To determine the effects of concomitant loss of EZH2 and JAK2V617F mutation in hematopoiesis, researchers generated Ezh2-deficient Jak2V617F-expressing mice. [Blood] Abstract P2X7 Receptor Inhibition Improves CD34 T-Cell Differentiation in HIV-Infected Immunological Nonresponders on c-ART Investigators used an in vitro system to analyze the T- and B-cell potential of CD34+ hematopoietic progenitor cells. Comparisons of immunological nonresponders (INRs) with matched HIV+ patients with high CD4+ T-cell counts (immune responders) revealed an impairment of the generation of T-cell progenitors, but not of B-cell progenitors, in INRs. [PLoS Pathog] Full Article Evidence that Hematopoietic Stem Cell Function Is Preserved during Aging in Long-Lived S6K1 Mutant Mice Scientists showed, using gene expression analyses, that there was a reduction in expression of cell cycle genes in young and aged S6 kinase 1 (S6K1-/-) bone marrow-derived c-Kit+ cells when compared to age-matched wild type mice, suggesting that these cells are more quiescent in S6K1-/- mice. [Oncotarget] Full Article Expansion and Hepatic Differentiation of Adult Blood-Derived CD34+ Progenitor Cells and Promotion of Liver Regeneration after Acute Injury Researchers report a new group of blood-derived CD34+ progenitor cells that have the ability to expand and differentiate into functional hepatocyte-like cells and promote liver regeneration. [Stem Cells Transl Med] Abstract | Full Article Spleen Hypoplasia Leads to Abnormal Stress Hematopoiesis in Mice with Loss of Pbx Homeoproteins in Splenic Mesenchyme Investigators explored the effects that genetic perturbation of the splenic mesenchymal niche has on hematopoiesis upon loss of members of the Pbx family of homeoproteins. [J Anat] Abstract CLINICAL RESEARCH Clinical Activity of Azacitidine in Patients Who Relapse after Allogeneic Stem Cell Transplantation for Acute Myeloid Leukemia Investigators studied the tolerability and activity of azacitidine in 181 patients who relapsed after an allograft for acute myeloid leukemia or myelodysplasia. [Haematologica] Abstract | Full Article Pharmacokinetic Variability of Mycophenolic Acid in Pediatric and Adult Patients with Hematopoietic Stem Cell Transplantation Investigators evaluated the pharmacokinetic variations of mycophenolic acid, the active metabolite of mycophenolate mofetil, in both pediatric and adult patients following hematopoietic stem cell transplantation. [J Clin Pharmacol] Abstract |