High-level ectopic HOXB4 expression confers a profound in vivo competitive growth advantage on human cord blood CD34+ cells, but impairs lymphomyeloid differentiation

Blood ◽  
2003 ◽  
Vol 101 (5) ◽  
pp. 1759-1768 ◽  
Author(s):  
Bernhard Schiedlmeier ◽  
Hannes Klump ◽  
Elke Will ◽  
Gökhan Arman-Kalcek ◽  
Zhixiong Li ◽  
...  

Ectopic retroviral expression of homeobox B4 (HOXB4) causes an accelerated and enhanced regeneration of murine hematopoietic stem cells (HSCs) and is not known to compromise any program of lineage differentiation. However, HOXB4 expression levels for expansion of human stem cells have still to be established. To test the proposed hypothesis that HOXB4 could become a prime tool for in vivo expansion of genetically modified human HSCs, we retrovirally overexpressed HOXB4 in purified cord blood (CB) CD34+ cells together with green fluorescent protein (GFP) as a reporter protein, and evaluated the impact of ectopic HOXB4 expression on proliferation and differentiation in vitro and in vivo. When injected separately into nonobese diabetic–severe combined immunodeficient (NOD/SCID) mice or in competition with control vector–transduced cells, HOXB4-overexpressing cord blood CD34+ cells had a selective growth advantage in vivo, which resulted in a marked enhancement of the primitive CD34+ subpopulation (P = .01). However, high HOXB4 expression substantially impaired the myeloerythroid differentiation program, and this was reflected in a severe reduction of erythroid and myeloid progenitors in vitro (P < .03) and in vivo (P = .01). Furthermore, HOXB4 overexpression also significantly reduced B-cell output (P < .01). These results show for the first time unwanted side effects of ectopic HOXB4 expression and therefore underscore the need to carefully determine the therapeutic window of HOXB4 expression levels before initializing clinical trials.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 516-516 ◽  
Author(s):  
Daniel Goff ◽  
Alice Shih ◽  
Angela Court Recart ◽  
Larisa Balaian ◽  
Ryan Chuang ◽  
...  

Abstract Abstract 516 Introduction: Several studies have demonstrated the role of leukemia stem cells (LSC) in the development and maintenance of human chronic myeloid leukemia (CML). These cells, which first develop in chronic phase CML (CP CML) with acquisition of the BCR-ABL fusion protein, are often quiescent and can be highly resistant to apoptosis induced by drugs and radiotherapy that target rapidly dividing cells. Data has also shown that CML LSC become increasingly resistant to BCR-ABL inhibition with progression to blast crisis CML (BC CML). Bcl-2 family proteins are key regulators of apoptosis and have been shown by numerous studies to regulate cancer resistance to chemotherapy. This family of proteins has also been implicated in the development of BC CML, however most studies have focused on CML cell lines and their expression of Bcl-2 family proteins in vitro. Thus, there is relatively little data on expression of Bcl-2 family proteins in primary CML LSC and on the role of these proteins in regulating chemotherapy resistance in CML LSC in vivo. As Bcl-2 family proteins are known regulators of chemotherapy resistance we hypothesized that human BC CML LSC may overexpress these proteins compared to normal hematopoietic stem cells. We analyzed Bcl-2 family mRNA and protein expression in CP CML and BC CML LSC and compared this expression to normal cord blood stem and progenitor cells. We also analyzed whether these cells were sensitive to chemotherapy treatment in vitro. Finally, we tested whether a high potency pan-Bcl-2 inhibitor, 97C1, could effectively kill CML LSC in vitro and in vivo. Methods: Bcl-2 and Mcl-1 protein expression was measured in primary CP CML, BC CML, and normal cord blood cells using intracellular FACS. We also measured Bcl-2, Mcl-1, Bcl-X, and Bfl-1 mRNA expression in FACS sorted CD34+CD38+lin− cells (LSC) from these samples. For all drug studies we used either serially transplanted CD34+ cells derived from primary BC CML patient samples or primary CD34+ normal cord blood cells. In vitro drug responses were tested by culturing CD34+ cells either alone or in co-culture with a mouse bone marrow stromal cell line (SL/M2). Effects on colony formation and replating were also tested by culturing sorted CD34+CD38+lin− cells in methylcellulose in the presence and absence of drug. For in vivo testing of 97C1 we transplanted neonatal RAG2-/-yc-/- mice with CD34+ cells from 3 different BC CML and cord blood samples. Transplanted mice were screened for peripheral blood engraftment at 6–8 weeks post-transplant and engrafted mice were then treated for 2 weeks with 97C1 by IP injection. Following the treatment period the mice were sacrificed and hemotapoietic organs were analyzed for human engraftment by FACS. Results: BC CML progenitors expressed higher levels of Bcl-2 and Mcl-1 protein compared to normal cord blood and chronic phase CML cells. mRNA expression of Mcl-1, Bcl-X, and Bfl-1 was also increased in BC CML progenitors compared to CP CML progenitors. While BC CML LSC cultured in vitro were resistant to etoposide and dasatinib-induced cell death, 97C1 treatment led to a dose-dependent increase in cell death along with a dose-dependent decrease in the frequency of CD34+CD38+lin− cells compared to vehicle treated controls. While cord blood progenitor cells were also sensitive to 97C1 treatment they had an IC50 around 10 times higher than that for the BC CML cells (100nM versus 10nM). Importantly, 97C1 treatment did not inhibit cord blood colony formation or colony replating in vitro. Mice transplanted with BC CML LSC developed CML in 6–8 weeks post-transplant with diffuse myeloid sarcomas and engraftment of human CD34+CD38+lin− cells in the peripheral blood, liver, spleen, and bone marrow. In vivo treatment with 97C1 led to a significant reduction in both total human engraftment and engraftment of CD34+CD38+lin− cells in all hematopoietic organs analyzed. Conclusion: Our results demonstrate that BC CML LSC are resistant to conventional chemotherapy but are sensitive to 97C1 in vitro and in vivo. Broad-spectrum inhibition of Bcl-2 family proteins may help to eliminate CML LSC while sparing normal hematopoietic stem and progenitor cells. Disclosures: Jamieson: CoronadoBiosciences: Research Funding; CIRM: Research Funding.


Blood ◽  
2011 ◽  
Vol 117 (18) ◽  
pp. 4773-4777 ◽  
Author(s):  
Hal E. Broxmeyer ◽  
Man-Ryul Lee ◽  
Giao Hangoc ◽  
Scott Cooper ◽  
Nutan Prasain ◽  
...  

Abstract Cryopreservation of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) is crucial for cord blood (CB) banking and transplantation. We evaluated recovery of functional HPC cryopreserved as mononuclear or unseparated cells for up to 23.5 years compared with prefreeze values of the same CB units. Highly efficient recovery (80%-100%) was apparent for granulocyte-macrophage and multipotential hematopoietic progenitors, although some collections had reproducible low recovery. Proliferative potential, response to multiple cytokines, and replating of HPC colonies was extensive. CD34+ cells isolated from CB cryopreserved for up to 21 years had long-term (≥ 6 month) engrafting capability in primary and secondary immunodeficient mice reflecting recovery of long-term repopulating, self-renewing HSCs. We recovered functionally responsive CD4+ and CD8+ T lymphocytes, generated induced pluripotent stem (iPS) cells with differentiation representing all 3 germ cell lineages in vitro and in vivo, and detected high proliferative endothelial colony forming cells, results of relevance to CB biology and banking.


Blood ◽  
2000 ◽  
Vol 95 (9) ◽  
pp. 2813-2820 ◽  
Author(s):  
Lisa Gallacher ◽  
Barbara Murdoch ◽  
Dongmei M. Wu ◽  
Francis N. Karanu ◽  
Mike Keeney ◽  
...  

Recent evidence indicates that human hematopoietic stem cell properties can be found among cells lacking CD34 and lineage commitment markers (CD34−Lin−). A major barrier in the further characterization of human CD34− stem cells is the inability to detect this population using in vitro assays because these cells only demonstrate hematopoietic activity in vivo. Using cell surface markers AC133 and CD7, subfractions were isolated within CD34−CD38−Lin− and CD34+CD38−Lin− cells derived from human cord blood. Although the majority of CD34−CD38−Lin− cells lack AC133 and express CD7, an extremely rare population of AC133+CD7− cells was identified at a frequency of 0.2%. Surprisingly, these AC133+CD7− cells were highly enriched for progenitor activity at a frequency equivalent to purified fractions of CD34+ stem cells, and they were the only subset among the CD34−CD38−Lin− population capable of giving rise to CD34+ cells in defined liquid cultures. Human cells were detected in the bone marrow of non-obese/severe combined immunodeficiency (NOD/SCID) mice 8 weeks after transplantation of ex vivo–cultured AC133+CD7− cells isolated from the CD34−CD38−Lin− population, whereas 400-fold greater numbers of the AC133−CD7− subset had no engraftment ability. These studies provide novel insights into the hierarchical relationship of the human stem cell compartment by identifying a rare population of primitive human CD34− cells that are detectable after transplantation in vivo, enriched for in vitro clonogenic capacity, and capable of differentiation into CD34+ cells.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1652-1652
Author(s):  
Patrick Ziegler ◽  
Steffen Boettcher ◽  
Hildegard Keppeler ◽  
Bettina Kirchner ◽  
Markus G. Manz

Abstract We recently demonstrated human T cell, B cell, dendritic cell, and natural interferon producing cell development and consecutive formation of primary and secondary lymphoid organs in Rag2−/−gc−/− mice, transplanted as newborns intra-hepatically (i.h.) with human CD34+ cord blood cells (Traggiai et al., Science 2004). Although these mice support high levels of human cell engraftment and continuous T and B cell formation as well as CD34+ cell maintenance in bone marrow over at least six month, the frequency of secondary recipient reconstituting human hematopoietic stem and progenitor cells within the CD34+ pool declines over time. Also, although some human immune responses are detectable upon vaccination with tetanus toxoid, or infection with human lymphotropic viruses such as EBV and HIV, these responses are somewhat weak compared to primary human responses, and are inconsistent in frequency. Thus, some factors sustaining human hematopoietic stem cells in bone marrow and immune responses in lymphoid tissues are either missing in the mouse environment, or are not cross-reactive on human cells. Human mesenchymal stem cells (MSCs) replicate as undifferentiated cells and are capable to differentiate to multiple mesenchymal tissues such as bone, cartilage, fat, muscle, tendon, as well as marrow and lymphoid organ stroma cells, at least in vitro (e.g. Pittenger et al., Science 1999). Moreover, it was shown that MSCs maintain CD34+ cells to some extend in vitro, and engraft at low frequency upon transplantation into adult immunodeficient mice or fetal sheep as detected by gene transcripts. We thus postulated that co-transplantation of cord blood CD34+ cells and MSCs into newborn mice might lead to engraftment of both cell types, and to provision of factors supporting CD34+ maintenance and immune system function. MSCs were isolated and expanded by plastic adherence in IMDM, supplemented with FCS and cortisone (first 3 weeks) from adult bone marrow, cord blood, and umbilical vein. To test their potential to support hemato-lymphopoiesis, MSCs were analyzed for human hemato-lymphotropic cytokine transcription and production by RT-PCR and ELISA, respectively. MSCs from all sources expressed gene-transcripts for IL-6, IL-7, IL-11, IL-15, SCF, TPO, FLT3L, M-CSF, GM-CSF, LIF, and SDF-1. Consistently, respective cytokines were detected in supernatants at the following, declining levels (pg/ml): IL-6 (10000-10E6) > SDF-1 > IL-11 > M-CSF > IL-7 > LIF > SCF > GM-CSF (0–450), while FLT3L and TPO were not detectable by ELISA. Upon i.h. transplantation of same passage MSCs (1X10E6) into sublethally irradiated (2x2 Gy) newborn Rag2−/−gc−/− mice, 2-week engraftment was demonstrated by species specific b2m-RT-PCR in thymus, spleen, lung, liver and heart in n=7 and additionally in thymus in n=3 out of 13 animals analyzed. Equally, GFP-RNA transcripts were detectable in the thymus for up to 6 weeks, the longest time followed, upon co-transplantation of same source CD34+ cells and retrovirally GFP-transduced MSCs in n=2 out of 4 animals. Further engraftment analysis of ongoing experiments will be presented. Overall, these results demonstrate that human MSC produce hemato-lymphoid cytokines and engraft in newborn transplanted Rag2−/−gc−/− mice, at least at early time-points analyzed. This model thus might allow studying hematopoietic cell and MSC-derived cell interaction, and might serve as a testing system for MSC delivered gene therapy in vivo.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1449-1449
Author(s):  
Naoya Uchida ◽  
Aylin Bonifacino ◽  
Allen E Krouse ◽  
Sandra D Price ◽  
Ross M Fasano ◽  
...  

Abstract Abstract 1449 Granulocyte colony-stimulating factor (G-CSF) in combination with plerixafor (AMD3100) produces significant mobilization of peripheral blood stem cells in the rhesus macaque model. The CD34+ cell population mobilized possesses a unique gene expression profile, suggesting a different proportion of progenitor/stem cells. To evaluate whether these CD34+ cells can stably reconstitute blood cells, we performed hematopoietic stem cell transplantation using G-CSF and plerixafor-mobilized rhesus CD34+ cells that were transduced with chimeric HIV1-based lentiviral vector including the SIV-capsid (χHIV vector). In our experiments, G-CSF and plerixafor mobilization (N=3) yielded a 2-fold higher CD34+ cell number, compared to that observed for G-CSF and stem cell factor (SCF) combination (N=5) (8.6 ± 1.8 × 107 vs. 3.6 ± 0.5 × 107, p<0.01). Transduction rates with χHIV vector, however, were 4-fold lower in G-CSF and plerixafor-mobilized CD34+ cells, compared to G-CSF and SCF (13 ± 4% vs. 57 ± 5%, p<0.01). CD123+ (IL3 receptor) rates were higher in CD34+ cells mobilized by G-CSF and plerixafor (16.4%) or plerixafor alone (21.3%), when compared to G-CSF alone (2.6%). To determine their repopulating ability, G-CSF and plerixafor-mobilized CD34+ cells were transduced with EGFP-expressing χHIV vector at MOI 50 and transplanted into lethally-irradiated rhesus macaques (N=3). Blood counts and transgene expression levels were followed for more than one year. Animals transplanted with G-CSF and plerixafor-mobilized cells showed engraftment of all lineages and earlier recovery of lymphocytes, compared to animals who received G-CSF and SCF-mobilized grafts (1200 ± 300/μl vs. 3300 ± 900/μl on day 30, p<0.05). One month after transplantation, there was a transient development of a skin rash, cold agglutinin reaction, and IgG and IgM type plasma paraproteins in one of the three animals transplanted with G-CSF and plerixafor cells. This animal had the most rapid lymphocyte recovery. These data suggested that G-CSF and plerixafor-mobilized CD34+ cells contained an increased amount of early lymphoid progenitor cells, compared to those arising from the G-CSF and SCF mobilization. One year after transplantation, transgene expression levels were 2–5% in the first animal, 2–5% in the second animal, and 5–10% in the third animal in all lineage cells. These data indicated G-CSF and plerixafor-mobilized CD34+ cells could stably reconstitute peripheral blood in the rhesus macaque. Next, we evaluated the correlation of transgene expression levels between in vitro bulk CD34+ cells and lymphocytes at one month, three months, and six months post-transplantation. At one and three months after transplantation, data from G-CSF and plerixafor mobilization showed higher ratio of %EGFP in lymphocytes to that of in vitro CD34+ cells when compared to that of G-CSF and SCF mobilization. At six months after transplantation the ratios were similar. These results again suggest that G-CSF and plerixafor-mobilized CD34+ cells might include a larger proportion of early lymphoid progenitor cells when compared to G-CSF and SCF mobilization. In summary, G-CSF and plerixafor mobilization increased CD34+ cell numbers. G-CSF and plerixafor-mobilized CD34+ cells contained an increased number of lymphoid progenitor cells and a hematopoietic stem cell population that was capable of reconstituting blood cells as demonstrated by earlier lymphoid recovery and stable multilineage transgene expression in vivo, respectively. Our findings should impact the development of new clinical mobilization protocols. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2348-2348
Author(s):  
Hirotaka Kawano ◽  
Tomotoshi Marumoto ◽  
Michiyo Okada ◽  
Tomoko Inoue ◽  
Takenobu Nii ◽  
...  

Abstract Abstract 2348 Since the successful establishment of human embryonic stem cells (ESCs) in 1998, transplantation of functional cells differentiated from ESCs to the specific impaired organ has been expected to cure its defective function [Thomson JA et al., Science 282:1145–47, 1998]. For the establishment of the regenerative medicine using ESCs, the preclinical studies utilizing animal model systems including non-human primates are essential. We have demonstrated that non-human primate of common marmoset (CM) is a suitable experimental animal for the preclinical studies of hematopoietic stem cells (HSCs) therapy [Hibino H et al., Blood 93:2839–48, 1999]. Since then we have continuously investigated the in vitro and in vivo differentiation of CM ESCs to hematopoietic cells by the exogenous hematopoietic gene transfer. In earlier study, we showed that the induction of CD34+ cells having a blood colony forming capacity from CM ESCs is promoted by lentiviral transduction of TAL1 cDNA [Kurita R et al., Stem Cells 24:2014-22,2006]. However those CD34+ cells did not have a bone marrow reconstituting ability in irradiated NOG (NOD/Shi-scid/IL-2Rγnull) mice, suggesting that transduction of TAL1 gene is not enough to induce functional HSCs which have self-renewal capability and multipotency. Thus we tried to find other hematopoietic genes being able to promote hematopoietic differetiation more efficiently than TAL1. We selected 6 genes (LYL1, HOXB4, BMI1, GATA2, c-MYB and LMO2) as candidates for factors that induce the differentiation from ESCs to HSCs, based on the comparison of gene expression level between human ESCs and HSCs by Digital Differential Display from the Uni-Gene database at the NCBI web site (http://www.ncbi.nlm.nih.gov/UniGene/). Then, we transduced the respective candidate gene in CM ESCs (Cj11), and performed embryoid body (EB) formation assay to induce their differentiation to HSCs for 9 days. We found that lentiviral transduction of LYL1, a basic helix-loop-helix transcription factor, in EBs derived from Cj11, one of CM ESC lines, markedly increased the number of cells positive for CD34, a marker for hematopoietic stem/progenitors. The lymphoblastic leukemia 1 (LYL1) was originally identified as the factor of a chromosomal translocation, resulting in T cell acute lymphoblastic leukemia [Mellentin JD et al., Cell 58:77-83.1989]. These class II bHLH transcription factors regulate gene expression by binding to target gene sequences as heterodimers with E-proteins, in association with Gata1 and Gata2 [Goldfarb AN et al., Blood 85:465-71.1995][Hofmann T et al., Oncogene 13:617-24.1996][Hsu HL et al., Proc Natl Acad Sci USA 91:5947-51.1994]. The Lyl1-deficient mice display the reduction of B cells and impaired long-term hematopoietic reconstitution capacity [Capron C et al., Blood 107:4678-4686. 2006]. And, overexpression of Lyl1 in mouse bone marrow cells induced the increase of HSCs, HPCs and lymphocytes in vitro and in vivo [Lukov GL et al., Leuk Res 35:405-12. 2011]. These information indicate that LYL1 plays important roles in hematopoietic differentiation in primate animals including human and common marmoset. To examine whether overexpression of LYL1 in EBs can promote hematopoietic differentiation in vitro we performed colony-forming unit (CFU) assay, and found that LYL1-overexpressing EBs showed the formation of multi-lineage blood cells consisting of erythroid cells, granulocytes and macrophages. Next, we analyzed gene expression level by RT-PCR, and found that the transduction of LYL1 induced the expression of various hematopoietic genes. These results suggested that the overexpression of LYL1 can promote the differentiation of CM ESCs to HSCs in vitro. Furthermore we found that the combined overexpression of TAL1 and LYL1 could enhance the differentiation of CD34+ cells from CM ESCs than the respective overexrpession of TAL1 or LYL1. Collectively, our novel technology to differentiate hematopoietic cells from ESCs by the transduction of specific transcription factors is novel, and might be applicable to expand human hematopoietic stem/progenitor cells in vitro for future regenerative medicine to cure human hematopoietic cell dyscrasias. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1192-1192
Author(s):  
Hirotaka Kawano ◽  
Tomotoshi Marumoto ◽  
Takafumi Hiramoto ◽  
Michiyo Okada ◽  
Tomoko Inoue ◽  
...  

Abstract Hematopoietic stem cell (HSC) transplantation is the most successful cellular therapy for the malignant hematopoietic diseases such as leukemia, and early recovery of host’s hematopoiesis after HSC transplantation has eagerly been expected to reduce the regimen related toxicity for many years. For the establishment of the safer and more efficient cell source for allogeneic or autologous HSC transplantation, HSCs differentiated from embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs) that show indefinite proliferation in an undifferentiated state and pluripotency, are considered to be one of the best candidates. Unfortunately, despite many recent efforts, the HSC-specific differentiation from ESCs and iPSCs remains poor [Kaufman, DS et al., 2001][Ledran MH et al., 2008]. In this study, we developed the new method to differentiate HSC from non-human primate ESC/iPSC. It has been reported that common marmoset (CM), a non-human primate, is a suitable experimental animal for the preclinical studies of HSC therapy [Hibino H et al., 1999]. We have been investigated the hematopoietic differentiation of CM ESCs into HSCs, and previously reported that the induction of CD34+ cells having a blood colony forming capacity from CM ESCs were promoted by lentiviral transduction of TAL1 cDNA [Kurita R et al., 2006]. However, those CD34+ cells did not have a bone marrow reconstituting ability in irradiated NOG (NOD/Shi-scid/IL-2Rγnull) mice, suggesting that transduction of TAL1 gene was not sufficient to induce functional HSCs which have self-renewal capability and multipotency. Thus, we tried to find other hematopoietic genes being able to promote hematopoietic differetiation more efficiently than TAL1. We selected 6 genes (LYL1, HOXB4, BMI1, GATA2, c-MYB and LMO2) as candidates for factors that induce the differentiation of ESCs into HSCs, based on the previous study of hematopoietic differentiation from human and mouse ESCs. And CM ESCs (Cj11) lentivirally transduced with the respective candidate gene were processed for embryoid body (EB) formation to induce their differentiation into HSCs for 9 days. We found that lentiviral transduction of LYL1 (lymphoblastic leukemia 1), a basic helix-loop-helix transcription factor, in EBs markedly increased the proportion of cells positive for CD34 (approximately 20% of LYL1-transduced cells). RT-PCR showed that LYL1-transduced EBs expressed various hematopoietic genes, such as TAL1, RUNX1 and c-KIT. To examine whether these CD34+ cells have the ability to differentiate into hematopoietic cells in vitro, we performed colony-forming unit (CFU) assay, and found that CD34+ cells in LYL1-transduced EBs could form multi-lineage blood colonies. Furthermore the number of blood colonies originated from CD34+CD45+ cells in LYL1-transduced EBs was almost the same as that from CD34+CD45+ cells derived from CM bone marrow. These results suggested that enforced expression of LYL1 in CM ESCs promoted the emergence of HSCs by EB formation in vitro. The LYL1 was originally identified as the factor of a chromosomal translocation, resulting in T cell acute lymphoblastic leukemia [Mellentin JD et al., 1989]. The Lyl1-deficient mice display the reduction of B cells and impaired long-term hematopoietic reconstitution capacity [Capron C et al., 2006]. And, transduction of Lyl1 in mouse bone marrow cells induced the increase of HSCs and lymphocytes in vitro and in vivo [Lukov GL et al., 2011]. Therefore we hypothesized that LYL1 may play essential roles in bone marrow reconstitution by HSCs differentiated from CM ESCs. To examine this, we transplanted CD34+ cells derived from LYL1-transduced CM ESCs into bone marrow of sublethally irradiated NOG mice, and found that about 7% of CD45+ cells derived from CM ESCs were detected in peripheral blood (PB) of recipient mice at 8 weeks after transplant (n=4). Although CM CD45+ cells disappeared at 12 weeks after transplant, CD34+ cells (about 3%) were still found in bone marrow at the same time point. Given that TAL1-transduced EBs derived from CM ESCs could not reconstitute bone marrow of irradiated mice at all, LYL1 rather than TAL1 might be a more appropriate transcription factor that can give rise to CD34+ HSCs having the enhanced capability of bone marrow reconstitution from CM ESCs. We are planning to do in vivo study to prove this hypothesis in CM. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2000 ◽  
Vol 96 (12) ◽  
pp. 3725-3733 ◽  
Author(s):  
Niels-Bjarne Woods ◽  
Cecilia Fahlman ◽  
Hanna Mikkola ◽  
Isao Hamaguchi ◽  
Karin Olsson ◽  
...  

The ability of lentiviral vectors to transfer genes into human hematopoietic stem cells was studied, using a human immunodeficiency virus 1 (HIV-1)–derived vector expressing the green fluorescence protein (GFP) downstream of the phosphoglycerate kinase (PGK) promoter and pseudotyped with the G protein of vesicular stomatitis virus (VSV). High-efficiency transduction of human cord blood CD34+cells was achieved after overnight incubation with vector particles. Sixteen to 28 percent of individual colony-forming units granulocyte-macrophage (CFU-GM) colonies derived from cord blood CD34+ cells were positive by polymerase chain reaction (PCR) for the GFP gene. The transduction efficiency of SCID-repopulating cells (SRC) within the cord blood CD34+population was assessed by serial transplantation into nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. When 400 000 cord blood CD34+ cells were transplanted into primary recipients, all primary and secondary recipients contained and expressed the transgene. Over 50% of CFU-GM colonies derived from the bone marrow of these primary and secondary recipients contained the vector on average as determined by PCR. Transplantation of transduced cells in limiting dilution generated GFP+ lymphoid and myeloid progeny cells that may have arisen from a single SRC. Inverse PCR analysis was used to amplify vector-chromosomal junctional fragments in colonies derived from SRC and confirmed that the vector was integrated. These results show that lentiviral vectors can efficiently transduce very primitive human hematopoietic progenitor and stem cells.


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