title: Lentiviral gene transfer regenerates hematopoietic stem cells in a mouse model for Mpl-deficient aplastic anemia.
abstract: Thpo/Mpl signaling plays an important role in the maintenance of hematopoietic stem cells (HSCs) in addition to its role in megakaryopoiesis. Patients with inactivating mutations in Mpl develop thrombocytopenia and aplastic anemia because of progressive loss of HSCs. Yet, it is unknown whether this loss of HSCs is an irreversible process. In this study, we used the Mpl knockout (Mpl(-/-)) mouse model and expressed Mpl from newly developed lentiviral vectors specifically in the physiologic Mpl target populations, namely, HSCs and megakaryocytes. After validating lineage-specific expression in vivo using lentiviral eGFP reporter vectors, we performed bone marrow transplantation of transduced Mpl(-/-) bone marrow cells into Mpl(-/-) mice. We show that restoration of Mpl expression from transcriptionally targeted vectors prevents lethal adverse reactions of ectopic Mpl expression, replenishes the HSC pool, restores stem cell properties, and corrects platelet production. In some mice, megakaryocyte counts were atypically high, accompanied by bone neo-formation and marrow fibrosis. Gene-corrected Mpl(-/-) cells had increased long-term repopulating potential, with a marked increase in lineage(-)Sca1(+)cKit(+) cells and early progenitor populations in reconstituted mice. Transcriptome analysis of lineage(-)Sca1(+)cKit(+) cells in Mpl-corrected mice showed functional adjustment of genes involved in HSC self-renewal.
authors.affiliation: Department of Experimental Hematology, Hannover Medical School, Carl-Neuberg-Strasse 1, Hannover, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Heckl
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Wicke
authors.forename: Martijn H
authors.initials: MH
authors.lastname: Brugman
authors.forename: Johann
authors.initials: J
authors.lastname: Meyer
authors.forename: Axel
authors.initials: A
authors.lastname: Schambach
authors.forename: Guntram
authors.initials: G
authors.lastname: Büsche
authors.forename: Matthias
authors.initials: M
authors.lastname: Ballmaier
authors.forename: Christopher
authors.initials: C
authors.lastname: Baum
authors.forename: Ute
authors.initials: U
authors.lastname: Modlich
mesh_terms: D000741:Anemia, Aplastic / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D000818:Animals; D019070:Cell Lineage / Q000235:genetics; D002478:Cells, Cultured; D004195:Disease Models, Animal; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D019169:Jurkat Cells; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011401:Promoter Regions, Genetic; D053628:Receptors, Thrombopoietin / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D012038:Regeneration / Q000235:genetics*
chemical_list: C481270:Mpl protein, mouse; D053628:Receptors, Thrombopoietin