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- Relander, Thomas, et al.
(författare)
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Low level of gene transfer to and engraftment of murine bone marrow cells from long-term bone marrow cultures
- 2000
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Ingår i: Experimental Hematology. - 1873-2399. ; 28:4, s. 373-381
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: We wanted to determine whether the long-term bone marrow culture (LTBMC) transduction system would lead to efficient gene transfer and engraftment of murine repopulating hematopoietic stem cells (HSC), particularly in nonablated recipients. MATERIALS AND METHODS: Congenic mouse strains expressing Ly 5.1 or Ly 5.2 and the GP+E86 cell line producing the MGirL22Y vector carrying the gene for enhanced GFP were used. Murine LTBMCs were established and demi-depopulated on days 7 and 14 with addition of vector supernatant on days 8 and 15. RESULTS: Cell recovery on day 21 was 21.3%+/-3.8% of input cells and CFU-C recovery was 9.7+/-3.4% as compared with CFU-C of input cells. In vitro transduction efficiency determined by CFU-C expressing GFP was 22.2%+/-1.6%. In irradiated (950 cGy) mice transplanted with 2x10(6) LTBMC cells, 94% of nucleated cells in the blood at week 16 were of donor origin. However, GFP was only detected at low level in a few animals at week 4 and not later. Analysis of bone marrow from these mice at week 20 did not show any GFP expression and semiquantitative PCR revealed a transgene level of <1%. When 3.5-20.8x10(6) LTBMC cells (corresponding to 20-100x10(6) fresh cells) were transplanted to nonablated recipients, no engraftment or GFP expression were detected. Competitive repopulation experiments showed that the long-term repopulation ability (LTRA) of the LTMC cells was only 7% of fresh cells. CONCLUSION: These results indicate that LTBMC transduction of murine cells leads to low-level transduction of progenitors, no gene transfer to repopulating stem cells, and reduction in LTRA in ablated and nonablated recipients.
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| 2. |
- Relander, Thomas, et al.
(författare)
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Oncoretroviral gene transfer to NOD/SCID repopulating cells using three different viral envelopes
- 2002
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Ingår i: Journal of Gene Medicine. - : Wiley. - 1521-2254 .- 1099-498X. ; 4:2, s. 122-132
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Tidskriftsartikel (refereegranskat)abstract
- Background The aim of this study was to investigate gene transfer to human umbilical cord blood (CB) CD34(+)/CD38(low) and NOD/SCID repopulating cells using oncoretroviral vectors and to compare the transduction efficiency using three different viral envelopes. Methods CB cells were transduced on Retronectin using an MSCV-based vector with the gene for GFP (MGIN), which was packaged into three different cell lines giving different envelopes: PG13-MGIN (GALV) 293GPG-MGIN (VSV-G) or AM12-MGIN (amphotropic). Results Sorted CD34(+)/CD38(low) cells were efficiently transduced after 3 days of cytokine stimulation and the percentage of GFP-positive cells was 61.8+/-6.6% (PG13-MGIN), 26.9+/-3.5% (293GPG-MGIN), and 39.3+/-4.8% (AM12-MGIN). For transplantation experiments, CD34(+) cells were prestimulated for 2 days before transduction on Retronectin preloaded with vector and with the addition of 1/10th volume of viral supernatant on day 3. On day 4, the expanded equivalent of 2.5 x 10(5) cells was injected into irradiated NOD/SCID mice. All three pseudotypes transduced NOD/SCID repopulating cells (SRCs) equally well in the presence of serum, but engraftment was reduced when compared with freshly thawed cells. Simultaneous transduction with all three vector pseudotypes increased the gene transfer efficiency to SRCs but engraftment was significantly impaired. There were difficulties in producing amphotropic vectors at high titers in serum-free medium and transduction of CD34(+) cells using VSV-G-pseudotyped vectors under serum-free conditions was very inefficient. In contrast, transduction with PG13-MGIN under serum-free conditions resulted in the maintenance of SRCs during transduction, high levels of engraftment (29.3+/-6.6%), and efficient gene transfer to SRCs (46.2+/-4.8%). Conclusions The best conditions for transduction and engraftment of CB SRCs were obtained with GALV-pseudo typed vectors using serum-free conditions. Copyright (C) 2002 John Wiley Sons, Ltd.
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| 3. |
- Relander, Thomas, et al.
(författare)
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Overexpression of Gibbon Ape Leukemia Virus (GALV) Receptor (GLVR1) on Human CD34(+) Cells Increases Gene Transfer Mediated by GALV Pseudotyped Vectors.
- 2002
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Ingår i: Molecular Therapy. - : Elsevier BV. - 1525-0024 .- 1525-0016. ; 6:3, s. 400-406
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Tidskriftsartikel (refereegranskat)abstract
- Retroviral transduction of CD34(+) cells on Retronectin using gibbon ape leukemia virus (GALV) pseudotyped vectors is inhibited by high concentrations of vector containing medium (VCM). Furthermore, this inhibitory activity is stable for at least 48 hours at 37 degrees C and partially blocks a second hit with a GALV pseudotyped vector. We hypothesized that this inhibition was due to interference at the receptor level between infectious and noninfectious vector particles and that it might be possible to overcome it by increasing receptor expression on target cells. Activation of protein kinase C in CD34(+) cells with the phorbol ester PMA (phorbol 12-myristate 13-acetate) increased the mRNA level of the GALV receptor (GLVR1) and the transduction efficiency (TE), and fully reversed the inhibition of transduction seen with high-titer GALV VCM. A murine stem cell virus (MSCV) vector with the GLVR1 receptor and green fluorescent protein cDNAs (MGLIG) was used to transduce fibroblasts, and clones expressing different levels of GLVR1 were isolated. The TE of these cells using a GALV vector correlated with the level of GLVR1 expression. When CD34(+) cells or K562 cells were first transduced with MGLIG and then with high-titer GALV VCM, no inhibition of transduction was seen. The low level of GLVR1 expression limits gene transfer to K562 and CD34(+) cells using GALV pseudotyped vectors, especially in the presence of high-titer VCMs.
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| 4. |
- Relander, Thomas
(författare)
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Retroviral gene transfer to repopulating hematopoietic cells
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hematopoietic stem cells (HSCs) have the capacity to maintain hematopoiesis throughout life. HSCs are ideal targets for permanent gene transfer, as the transgene will be expressed in all the progeny of the gene-modified stem cells. The aim of this thesis was to optimize conditions for retroviral gene transfer to human candidate HSCs and to study mechanisms interfering with efficient gene transfer. First, long-term bone marrow culture transduction of murine hematopoietic cells was investigated, showing inefficient gene transfer and loss of repopulating ability of the transduced cells. Thereafter, transduction of human CD34+ cells was studied using the MGIN vector with the GALV, amphotropic and VSV-G envelopes. Amphotropic, and, particularly, GALV vector containing medium (VCM) inhibited transduction on fibronectin preloaded with vector. GALV VCM inhibited transduction of NOD/SCID repopulating cells (SRCs) as well. Optimal transduction was seen with vector preloaded to fibronectin and cells added in medium without vector. To study the mechanisms underlying GALV vector mediated inhibition, the GLVR1 receptor was overexpressed using phorbol ester or a retroviral vector, showing complete abolishment the inhibitory effect from GALV VCM. Together our results show that low levels of GLVR1, in combination with non-infectious vector particles in VCM, limit transduction of hematopoietic progenitors. Finally, vectors with GALV, amphotropic and VSV-G envelopes were compared regarding their ability to transfer genes to SRCs. The different pseudotypes were equally efficient in the presence of serum with an average transduction efficiency of 25-33 % of SRCs, but the engraftment levels were reduced compared to fresh cells. Only the GALV vectors could be used under serum-free conditions showing high level transduction of SRCs (46 %) without loss of SRC frequency as analyzed by transplantation at limiting cell numbers. In conclusion, under optimal conditions, highly efficient gene transfer human hematopoietic cells with NOD/SCID repopulating ability could be accomplished. However, for clinical applications, safety issues, particularly regarding the risk of mutagenesis from retroviral vector insertion into the genome of repopulating cells, need to be adressed carefully.
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| 5. |
- Relander, Thomas, et al.
(författare)
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Retroviral transduction of human CD34+ cells on fibronectin fragment CH-296 is inhibited by high concentrations of vector containing medium
- 2001
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Ingår i: Journal of Gene Medicine. - 1521-2254. ; 3:3, s. 207-218
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The objective of the present study was to optimize conditions for retroviral transduction of human cord blood (CB) CD34+ cells and to reveal mechanisms which interfere with efficient gene transfer. METHODS: An MSCV based retroviral vector with the gene for enhanced green fluorescent protein (MGIN) produced by GP+envAM12 (amphotropic envelope), PG13 (gibbon ape leukemia virus envelope) or 293GPG (vesicular stomatitis virus envelope) cell lines was used to transduce cord blood CD34+ cells on Retronectin (fibronectin fragment CH-296) in three different ways: either in vector containing medium (VCM), in fresh medium on Retronectin pre-loaded with vector or in VCM on Retronectin pre-loaded with vector. RESULTS: Paradoxically, the transduction efficiency obtained with pre-load of vector onto Retronectin alone was higher than pre-load plus VCM for PG13-MGIN (67.9 +/- 6.0% vs 24.9 +/- 8.0%) and AM12-MGIN (47.5 +/- 5.8% vs 38.7 +/- 2.2%). Further experiments showed that transduction on Retronectin pre-loaded with PG13-MGIN or AM12-MGIN was inhibited by the presence of the same VCM at high concentrations, but not by the presence of a VCM with a different receptor specificity. If no pre-load of vector was performed, the highest transduction efficiencies were seen when VCMs were diluted 1:10 (MOIs of 3). The inhibitory effect of high titer PG13-MGIN VCM was confirmed in more primitive CD34+CD38low cells and in NOD/SCID repopulating cells, and was also seen in experiments with bone marrow CD34+ cells. CONCLUSIONS: Retroviral transduction of CB CD34+ cells on Retronectin is inhibited by high titer PG13 and GP+envAM12 vector containing medium. Efficient gene transfer to human hematopoietic cells can be obtained by preload alone of the vector onto Retronectin. These findings are of importance for the design of transduction protocols for repopulating hematopoietic cells.
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