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

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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; Hammar, Petter; Larsson, Peter; Sirenko, Oksana; Flippin, Lee A.; Cammenga, Jörg; Jonsson, Jan-Ingvar.

In: Experimental Hematology, Vol. 38, No. 4, 2010, p. 301-310.

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Eliasson, Pernilla ; Rehn, Matilda ; Hammar, Petter ; Larsson, Peter ; Sirenko, Oksana ; Flippin, Lee A. ; Cammenga, Jörg ; Jonsson, Jan-Ingvar. / Hypoxia mediates low cell-cycle activity and increases the proportion of long-term reconstituting hematopoietic stem cells during in vitro culture. In: Experimental Hematology. 2010 ; Vol. 38, No. 4. pp. 301-310.

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TY - JOUR

T1 - Hypoxia mediates low cell-cycle activity and increases the proportion of long-term reconstituting hematopoietic stem cells during in vitro culture

AU - Eliasson, Pernilla

AU - Rehn, Matilda

AU - Hammar, Petter

AU - Larsson, Peter

AU - Sirenko, Oksana

AU - Flippin, Lee A.

AU - Cammenga, Jörg

AU - Jonsson, Jan-Ingvar

PY - 2010

Y1 - 2010

N2 - 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.

AB - 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.

U2 - 10.1016/j.exphem.2010.01.005

DO - 10.1016/j.exphem.2010.01.005

M3 - Article

VL - 38

SP - 301

EP - 310

JO - Experimental Hematology

JF - Experimental Hematology

SN - 1873-2399

IS - 4

ER -