Hypoxia mediates low cell-cycle activity and increases the proportion of long-term reconstituting hematopoietic stem cells during in vitro culture

Research output: Contribution to journalArticle

Abstract

Objective. Recent evidence suggests that hematopoietic stem cells (HSCs) in the bone marrow (BM) are located in areas where the environment is hypoxic. Although previous studies have demonstrated positive effects by hypoxia, its role in HSC maintenance has not been fully elucidated, neither has the molecular mechanisms been delineated. Here, we have investigated the consequence of in vitro incubation of HSCs in hypoxia prior to transplantation and analyzed the role of hypoxia-inducible factor (HIF)-1 alpha. Materials and Methods. HSC and progenitor populations isolated from mouse BM were cultured in 20% or 1% O-2, and analyzed for effects on cell cycle, expression of cyclin-dependent kinase inhibitors genes, and reconstituting ability to lethally irradiated mice. The involvement of HIF-1 alpha was studied using methods of protein stabilization and gene silencing. Results. When long-term FLT3(-)CD34(-)Lin(-)Sca-1(+)c-Kit(+) (LSK) cells were cultured in hypoxia, cell numbers were significantly reduced in comparison to normoxia. This was due to a decrease in proliferation and more cells accumulating in G(0). Moreover, the proportion of HSCs with long-term engraftment potential was increased. Whereas expression of the cyclin-dependent kinase inhibitor genes p21(cip1), p27(Kip1), and p57(Kip2) increased in LSK cells by hypoxia, only p21(cip1) was upregulated in FLT3(-)CD34(-)LSK cells. We could demonstrate that expression of p27(KiP1) and p57(Kip2) was dependent of HIF-1 alpha. Surprisingly, overexpression of constitutively active HIF-1 alpha or treatment with the HIF stabilizer agent FG-4497 led to a reduction in HSC reconstituting ability. Conclusions. Our results imply that hypoxia, in part via HIF-1 alpha, maintains HSCs by decreasing proliferation and favoring quiescence. (C) 2010 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc.

Details

Authors
  • Pernilla Eliasson
  • Matilda Rehn
  • Petter Hammar
  • Peter Larsson
  • Oksana Sirenko
  • Lee A. Flippin
  • Jörg Cammenga
  • Jan-Ingvar Jonsson
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Hematology
Original languageEnglish
Pages (from-to)301-310
JournalExperimental Hematology
Volume38
Issue number4
Publication statusPublished - 2010
Publication categoryResearch
Peer-reviewedYes

Related research output

Rehn, M., 2011, Molecular Medicine and Gene Therapy, Lund University. 125 p.

Research output: ThesisDoctoral Thesis (compilation)

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