Blood Journal
Leading the way in experimental and clinical research in hematology

Lentiviral gene transfer regenerates hematopoietic stem cells in a mouse model for Mpl-deficient aplastic anemia

  1. Dirk Heckl1,
  2. Daniel C. Wicke1,
  3. Martijn H. Brugman1,
  4. Johann Meyer1,
  5. Axel Schambach1,
  6. Guntram Büsche2,
  7. Matthias Ballmaier3,
  8. Christopher Baum1, and
  9. Ute Modlich1
  1. Departments of 1Experimental Hematology,
  2. 2Pathology, and
  3. 3Pediatric Hematology, Hannover Medical School, Hannover, Germany

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 lineageSca1+cKit+ cells and early progenitor populations in reconstituted mice. Transcriptome analysis of lineageSca1+cKit+ cells in Mpl-corrected mice showed functional adjustment of genes involved in HSC self-renewal.

  • Submitted September 20, 2010.
  • Accepted December 24, 2010.
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