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

Eliasson, Pernilla; Rehn, Matilda LU ; Hammar, Petter; Larsson, Peter; Sirenko, Oksana; Flippin, Lee A.; Cammenga, Jörg LU and Jonsson, Jan-Ingvar (2010) In Experimental Hematology 38(4). p.301-310
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Experimental Hematology
volume
38
issue
4
pages
301 - 310
publisher
Elsevier
external identifiers
  • wos:000276054300005
  • scopus:77950860807
ISSN
1873-2399
DOI
10.1016/j.exphem.2010.01.005
language
English
LU publication?
yes
id
01ae6585-330c-4fff-9f7a-a9ccff57137d (old id 1587770)
date added to LUP
2010-04-22 14:33:32
date last changed
2018-06-24 03:18:06
@article{01ae6585-330c-4fff-9f7a-a9ccff57137d,
  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.},
  author       = {Eliasson, Pernilla and Rehn, Matilda and Hammar, Petter and Larsson, Peter and Sirenko, Oksana and Flippin, Lee A. and Cammenga, Jörg and Jonsson, Jan-Ingvar},
  issn         = {1873-2399},
  language     = {eng},
  number       = {4},
  pages        = {301--310},
  publisher    = {Elsevier},
  series       = {Experimental Hematology},
  title        = {Hypoxia mediates low cell-cycle activity and increases the proportion of long-term reconstituting hematopoietic stem cells during in vitro culture},
  url          = {http://dx.doi.org/10.1016/j.exphem.2010.01.005},
  volume       = {38},
  year         = {2010},
}