Cellular and Molecular Pathways Governing Hematopoietic Stem Cell Fate

Research output: ThesisDoctoral Thesis (compilation)

Abstract

Hematopoietic Stem Cells (HSCs) have been defined to have abilities of both self-renewal and multi-lineage differen-tiation. The balance between these abilities is rigorously controlled under steady-state status (homeostasis) and when the normal processes of self-renewal and differentiation become deregulated, a disorder of blood system (such as leukemias) can occur. HSCs are enriched in lineage negative (Lin-), SCA-1 positive and c-KIT positive (LSK) cells in mouse bone marrow (BM), as well as in the Lin(-)CD34(+) cells in human BM or cord blood. However, the LSK compartment is heterogeneous, containing long-term (LT) and short-term (ST) self-renewing HSCs as well as non-self-renewing multipotent progen-itors (MPPs) and demanding further subfractionation of this population to allow for detailed functional investiga-tions. Even though these different subpopulations are phenotypically and functionally characterized, it is still poorly understood how LT-HSCs make a cell fate decision to differentiate into ST-HSCs and further to MPPs, as well as how the cellular and molecular pathways regulate HSC fate decisions. In this thesis, we identified two distinct subpopulations within BM and fetal liver LSK compartment: ST-HSC population identified as LSKCD34(+/hi)FLT3(-) cells and lymphoid primed multipotent progenitors (termed LMPPs) represented by LSKCD34(+)FLT3(hi) cells. LSKCD34(+/hi)FLT3(-) cells are capable of rapid but short-term reconstitution, high colony-forming units-spleen (CFU-S) and radio-protective activities while LSKCD34(+)FLT3(hi) cells can give rise to lymphoid and myeloid cells but have no self-renewal activity and little or no megakaryocytic-erythrocytic (MkE) potentials. This was further supported by gene expression analysis revealing a modulation of genetic programs in the transition from the ST-HSC to the LMPP, with down-regulation of MkE and up-regulation of lymphoid gene programs. The work has also investigated the regulatory roles of extrinsic modulators on HSC function. We found that HSC self-renewal is negatively regulated by activation of the IFN-gamma and Fas pathways, through the promotion of HSC differentiation.

Details

Authors
  • Liping Yang
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cell and Molecular Biology

Keywords

  • stem cell, hematopoiesis, bone marrow transplantation, lineage commitment, cytokine, Medicine (human and vertebrates), Clinical genetics, Klinisk genetik, extracellulära vätskor, Hematologi, Medicin (människa och djur), extracellular fluids, Haematology
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
  • Sten Eirik W Jacobsen, Supervisor
Award date2006 Jan 21
Publisher
  • Lund Center for Stem Cell Biology and Cell Therapy
Print ISBNs91-85481-32-7
Publication statusPublished - 2006
Publication categoryResearch

Bibliographic note

Defence details Date: 2006-01-21 Time: 10:00 Place: Segerfalksalen, BMC, Lund External reviewer(s) Name: Spangrude, Gerald Title: Professor Affiliation: University of Utah School of Medicine, USA --- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Hematopoietic Stem Cell Laboratory (013022012)