| 1. |
- Anderson, Kristina, et al.
(författare)
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Ectopic expression of PAX5 promotes maintenance of biphenotypic myeloid progenitors coexpressing myeloid and B-cell lineage-associated genes
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 109:9, s. 3697-3705
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor PAX5 is a critical regulator of B-cell commitment and development. Although normally not expressed in myeloid progenitors, PAX5 has recently been shown to be frequently expressed in myeloid malignancies and to suppress expression of myeloid differentiation genes, compatible with an effect on the differentiation or maintenance of myeloid progenitors. However, previous studies in which PAX5 was ectopically expressed in normal myeloid progenitors in vivo and in vitro provided conflicting results as to the effect of PAX5 on myeloid development. Herein, we demonstrate that on ectopic expression of PAX5 in bone marrow multipotent stem/progenitor cells, cells with a biphenotypic B220+GR-1/MAC-1+ phenotype are produced. These remain cytokine-dependent, but unlike control-transduced cells they sustain long-term generation of myeloid progenitors in vitro and remain capable of myeloid differentiation. Notably, PAX5+B220+GR-1/MAC- 1+ myeloid progenitors coexpress, at the single-cell level, myeloid genes and otherwise B-cell-specific PAX5 target genes. These findings establish that ectopic expression of PAX5 introduces extensive self-renewal properties in otherwise short-lived myeloid progenitors. Along with the established ectopic expression of PAX5 in acute myeloid leukemia, this motivates a careful investigation of the potential involvement of ectopic PAX5 expression in myeloid and biphenotypic leukemias. © 2007 by The American Society of Hematology.
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| 2. |
- Anderson, Kristina, et al.
(författare)
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Ectopic expression of PAX5 promotes self renewal of bi-phenotypic myeloid progenitors co-expressing myeloid and B-cell lineage associated genes.
- 2007
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Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 109:Jan 11, s. 3697-3705
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factor PAX5 is a critical regulator of B-cell commitment and development. Although normally not expressed in myeloid progenitors, PAX5 has recently been shown to be frequently expressed in myeloid malignancies and to suppress expression of myeloid differentiation genes, compatible with an effect on the differentiation or maintenance of myeloid progenitors. However, previous studies in which PAX5 was ectopically expressed in normal myeloid progenitors in vivo and in vitro provided conflicting results as to the effect of PAX5 on myeloid development. Herein, we demonstrate that on ectopic expression of PAX5 in bone marrow multipotent stem/progenitor cells, cells with a biphenotypic B220+GR-1/MAC-1+ phenotype are produced. These remain cytokine-dependent, but unlike control-transduced cells they sustain long-term generation of myeloid progenitors in vitro and remain capable of myeloid differentiation. Notably, PAX5+B220+GR-1/MAC-1+ myeloid progenitors coexpress, at the single-cell level, myeloid genes and otherwise B-cell–specific PAX5 target genes. These findings establish that ectopic expression of PAX5 introduces extensive self-renewal properties in otherwise short-lived myeloid progenitors. Along with the established ectopic expression of PAX5 in acute myeloid leukemia, this motivates a careful investigation of the potential involvement of ectopic PAX5 expression in myeloid and biphenotypic leukemias.
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| 3. |
- Björgvinsdottir, Helga, et al.
(författare)
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Efficient Oncoretroviral Transduction of Extended Long-Term Culture-Initiating Cells and NOD/SCID Repopulating Cells: Enhanced Reconstitution with Gene-Marked Cells Through an Ex Vivo Expansion Approach.
- 2002
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Ingår i: Human Gene Therapy. - 1043-0342. ; 13:9, s. 1061-1073
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Tidskriftsartikel (refereegranskat)abstract
- Recent developments of surrogate assays for human hematopoietic stem cells (HSC) have facilitated efforts at improving HSC gene transfer efficiency. Through the use of xenograft transplantation models, such as nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice, successful oncoretroviral gene transfer to transplantable hematopoietic cells has been achieved. However, because of the low frequency and/or homing efficiency of SCID repopulating cells (SRC) in bone marrow (BM), studies have primarily focused on cord blood (CB). The recently developed extended (> 60 days) long-term culture-initiating cell (ELTC-IC) assay detects an infrequent and highly quiescent candidate stem cell population in BM as well as CB of the CD34(+)CD38(-) phenotype. Although these characteristics suggest that ELTC-IC and SRC might be closely related, attempts to oncoretrovirally transduce ELTC-IC have been unsuccessful. Here, recently developed conditions (high concentrations of SCF + FL + Tpo in serum-free medium) supporting expansion of BM CD34(+)CD38(-) 12 week ELTC-IC promoted efficient oncoretroviral transduction of BM and CB ELTC-IC. Although SRC can be transduced with oncoretroviral vectors, this is frequently associated with loss of reconstituting activity, posing a problem for development of clinical HSC gene therapy. However, previous attempts at expanding transduced HSC posttransduction resulted in compromised rather than improved gene marking. Utilizing conditions promoting cell divisions and transduction of ELTC-IC we show that although 5 days of ex vivo culture is sufficient to obtain maximum gene transfer efficiency to SRC, extension of the expansion period to 12 days significantly enhances multilineage reconstitution activity of transduced SRC, supporting the feasibility of improving gene marking through ex vivo expansion.
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