Highly efficient transduction of the green fluorescent protein gene in human umbilical cord blood stem cells capable of cobblestone formation in long-term cultures and multilineage engraftment of immunodeficient mice.
ABSTRACT Purified CD34(+) and CD34(+)CD38(-) human umbilical cord blood (UCB) cells were transduced with the recombinant variant of Moloney murine leukemia virus (MoMLV) MFG-EGFP or with SF-EGFP, in which EGFP expression is driven by a hybrid promoter of the spleen focus-forming virus (SFFV) and the murine embryonic stem cell virus (MESV). Infectious MFG-EGFP virus was produced by an amphotropic virus producer cell line (GP+envAm12). SF-EGFP was produced in the PG13 cell line pseudotyped for the gibbon ape leukemia virus (GaLV) envelope proteins. Using a 2-day growth factor prestimulation, followed by a 2-day, fibronectin fragment CH-296-supported transduction, CD34(+) and CD34(+)CD38(-) UCB subsets were efficiently transduced using either vector. The use of the SF-EGFP/PG13 retroviral packaging cell combination consistently resulted in twofold higher levels of EGFP-expressing cells than the MFG-EGFP/Am12 combination. Transplantation of 10(5) input equivalent transduced CD34(+) or 5 x 10(3) input equivalent CD34(+)CD38(-) UCB cells in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice resulted in median engraftment percentages of 8% and 5%, respectively, which showed that the in vivo repopulating ability of the cells had been retained. In addition, mice engrafted after transplantation of transduced CD34(+) cells using the MFG-EGFP/Am12 or the SF-EGFP/PG13 combination expressed EGFP with median values of 2% and 23% of human CD45(+) cells, respectively, which showed that the NOD/SCID repopulating cells were successfully transduced. EGFP+ cells were found in all human hematopoietic lineages produced in NOD/SCID mice including human progenitors with in vitro clonogenic ability. EGFP-expressing cells were also detected in the human cobblestone area-forming cell (CAFC) assay at 2 to 6 weeks of culture on the murine stromal cell line FBMD-1. During the transduction procedure the absolute numbers of CAFC week 6 increased 5- to 10-fold. The transduction efficiency of this progenitor cell subset was similar to the fraction of EGFP+ human cells in the bone marrow of the NOD/SCID mice transplanted with MFG-EGFP/Am12 or SF-EGFP/PG13 transduced CD34(+) cells, ie, 6% and 27%, respectively. The study thus shows that purified CD34(+) and highly purified CD34(+)CD38(-) UCB cells can be transduced efficiently with preservation of repopulating ability. The SF-EGFP/PG13 vector/packaging cell combination was much more effective in transducing repopulating cells than the MFG-EGFP/Am12 combination.
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ABSTRACT: Conventional assays for hematopoietic progenitor cells (HPCs) require long-term culturing, a labor-intensive procedure, and technique proficiency. We aimed to develop a high-throughput method to determine frequency of quiescent primitive HPCs by a combination of the micro-multiwell plate and 5-fluorouracil (5-FU) treatment. The micro-multiwell plate was made of a silicone sheet with a 6 x 6 array of 1-mm diameter holes and a glass substrate. To enrich primitive HPCs in a CD34 population, CD34 cells and stromal cells were applied to micro-multiwells and cultured in the presence of 5-FU for 2 days. The quiescent primitive HPCs that survived after 5-FU treatment were then expanded with cytokines in the absence of 5-FU for a further 10 days. After culturing, cells were immunostained and the number of primitive HPCs in inoculated CD34 cells was estimated from fluorescent intensity for each well under a stereoscopic fluorescent microscope. The frequencies of primitive HPCs correlated well with frequencies of cobblestone area-forming cells for two CD34 cell lots. Our method allows high-throughput screening for primitive HPCs in CD34 cells.Analytical and Bioanalytical Chemistry 03/2008; 391(8):2753-8. · 3.66 Impact Factor
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ABSTRACT: FLT3 and its ligand (FL) are one of the regulators of normal hematopoiesis. Ligand-independent activation of FLT3 occurs in about 30% of acute myeloid leukemia cases and is one goal for selectively targeted therapies. However, the function of FLT3/FL in the regulation of non-malignant immature hematopoietic cells is poorly characterized. In order to elucidate the role of FLT3 in normal hematopoiesis, human adult CD34(+) hematopoietic progenitor cells were cultured in cytokine-supplemented liquid culture in the presence or absence of FLT3 inhibition by CEP-701 (lestaurtinib). Total cell number, lineage-committed, and primitive progenitors and apoptosis were assayed. FLT3 expression and FL secretion in various conditions were analyzed by fluorescent activated cell sorter and enzyme-linked immunosorbent assay. Effects of nonspecific targeting of FLT3 were evaluated with addition of imatinib (Gleevec) to cell cultures. It is demonstrated that FLT3 inhibition impaired cell and progenitor cell growth and increased the rate in apoptosis. Effects were observed independent of addition of FL. The dose-dependent growth inhibition was partially equalized by inhibiting FL with a neutralizing antibody. FLT3 inhibition resulted in markedly increased production of FL by cultured CD34(+) cells as well as upregulation of FLT3 expression. Imatinib mimicked effects of selective FLT3 inhibition. In conclusion, FLT3 and its ligand regulate proliferation of hematopoietic progenitor cells in an autocrine/paracrine manner Nonspecific inhibition of FLT3 may contribute to hematotoxicity caused by imatinib treatment.Annals of Hematology 10/2008; 88(3):203-11. · 2.87 Impact Factor
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ABSTRACT: Gene transfer into hematopoietic cells using viral vectors has focused mostly on lymphocytes and hematopoietic stem cells (HSCs). HSCs have been considered particularly important as target cells because of their pluripotency and ability to reconstitute hematopoiesis after myeloablation and transplantation. HSCs are believed to have the ability to live a long time, perhaps a lifetime, in the recipient following bone marrow transplantation. Genetic correction of HSCs can therefore potentially last a lifetime and permanently cure hematologic disorders in which genetic deficiencies cause the pathology. Oncoretroviral vectors have been the main vectors used for HSCs because of their ability to integrate into the chromosomes of their target cells. Gene-transfer efficiency of murine HSCs is high using oncoretroviral vectors. In contrast, gene-transfer efficiency using the same viral vectors to transduce human HSCs or HSCs from large animals has been much lower. Although these difficulties may have several causes, the main reason for the low efficiency of human HSC transduction with oncoretroviral vectors is probably because of the nondividing nature of HSCs. Murine HSCs can be easily stimulated to divide in culture, whereas it is more problematic to stimulate human HSCs to divide rapidly in vitro. Because oncoretroviral vectors require dividing target cells for successful nuclear import of the preintegration complex and subsequent integration of the provirus, only the dividing fraction of the target cells can be transduced. This review focuses on gene transfer into human hematopoietic cells, particularly human HSCs. We review the clinical studies that have been reported, including the recent successful gene therapy for X-linked severe combined immunodeficiency. We discuss how the gene-transfer efficiency of human HSCs can be improved using oncoretroviral and lentiviral vectors.International Journal of Hematology 04/2012; 73(2):162-169. · 1.68 Impact Factor