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Blood, 1 August 2006, Vol. 108, No. 3, pp. 1084-1091. Prepublished online as a Blood First Edition Paper on April 6, 2006; DOI 10.1182/blood-2005-09-008904.
STEM CELLS IN HEMATOLOGY Human short-term repopulating cells have enhanced telomerase reverse transcriptase expressionFrom the Section of Molecular Medicine and Gene Therapy, Lund Strategic Research Center for Stem Cell Biology and Cell Therapy; and Section of Immunology, The Rausing Laboratory, Division of Neurosurgery, Lund University Hospital, Lund University, Sweden.
Telomerase activity has been suggested to be critically involved in hematopoietic stem cell (HSC) self-renewal. However, it has been unclear whether human HSCs have telomerase activity and how telomerase activity is regulated within the HSC and progenitor pool. Here, we isolated living cord-blood (CB) CD34+ cells with up-regulated human telomerase reverse transcriptase (hTERT) expression by using an hTERT-reporting adenoviral vector encoding destabilized green fluorescent protein (dGFP) driven by the hTERT promoter, and functionally characterized them in comparison with control vectortransduced CD34+ cells expressing GFP. Following a 2-day serum-free transduction protocol, cells were sorted into a dGFP+ and a GFP+ fraction. Cell-cycle analysis revealed that the dGFP+ cells had a greater proportion of cells in S/G2/M phase compared with the GFP+ cells, (56% ± 1.8% vs 35% ± 4.3%; P < .001) and fewer cells in G0 phase (8.1% ± 3.0% vs 20% ± 4.7%; P < .01) However, the colony-forming and short-term nonobese diabetic/severe combined immunodeficient (NOD/SCID) B2m/ mice bone marrowrepopulating capacities were similar between the dGFP+ and the GFP+ cells. Interestingly, the dGFP+ cells had a 6-fold lower repopulating capacity in NOD/SCID mice compared with the GFP+ cells and lacked secondary NOD/SCID B2m/ mice bone marrowrepopulating capacity. Thus, up-regulation of hTERT expression within the CB HSC pool is accompanied by decreased self-renewal capacity.
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| Copyright © 2006 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||