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Knockdown of HPRT for selection of genetically modified human hematopoietic progenitor cells.

ABSTRACT: The inability to obtain sufficient numbers of transduced cells remains a limitation in gene therapy. One strategy to address this limitation is in vivo pharmacologic selection of transduced cells. We have previously shown that knockdown of HPRT using lentiviral delivered shRNA facilitates efficient selection of transduced murine hematopoietic progenitor cells (HPC) using 6-thioguanine (6TG). Herein, we now extend these studies to human HPC. We tested multiple shRNA constructs in human derived cell lines and identified the optimal shRNA sequence for knockdown of HPRT and 6TG resistance. We then tested this vector in human umbilical cord blood derived HPC in vitro and in NOD/SCID recipients. Knockdown of HPRT effectively provided resistance to 6TG in vitro. 6TG treatment of mice resulted in increased percentages of transduced human CD45(+) cells in the peripheral blood and in the spleen in particular, in both myeloid and lymphoid compartments. 6TG treatment of secondary recipients resulted in higher percentages of transduced human cells in the bone marrow, confirming selection from the progeny of long-term repopulating HPCs. However, the extent of selection of cells in the bone marrow at the doses of 6TG tested and the toxicity of higher doses, suggest that this strategy may be limited to selection of more committed progenitor cells. Together, these data suggest that human HPC can be programmed to be resistant to purine analogs, but that HPRT knockdown/6TG-based selection may not be robust enough for in vivo selection.

SUBMITTER: Choudhary R

PROVIDER: S-EPMC3598703 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Knockdown of HPRT for selection of genetically modified human hematopoietic progenitor cells.

Choudhary Rashmi R Baturin Dmitry D Fosmire Susan S Freed Brian B Porter Christopher C CC

PloS one 20130315 3

The inability to obtain sufficient numbers of transduced cells remains a limitation in gene therapy. One strategy to address this limitation is in vivo pharmacologic selection of transduced cells. We have previously shown that knockdown of HPRT using lentiviral delivered shRNA facilitates efficient selection of transduced murine hematopoietic progenitor cells (HPC) using 6-thioguanine (6TG). Herein, we now extend these studies to human HPC. We tested multiple shRNA constructs in human derived ce ...[more]

PMID: 23555045

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Project description:Programmed cell death-2 (PDCD2) protein is enriched in embryonic, hematopoietic, and neural stem cells, however, its function in stem/progenitor cell differentiation is unclear. We investigated the effects of PDCD2 knockdown on the development and differentiation of hematopoietic progenitor cells (HPC). CD34(+) cells derived from normal human bone marrow and K562 leukemic cells were effectively transduced with short-hairpin RNA to knockdown PDCD2. Colony-forming assays were used to investigate the effects of PDCD2 loss on HPC clonogenic potential and on 12-O-tetradecanoyl-phorbol-13-acetate-and arabinofuranosylcytosine-induced terminal differentiation. In CD34(+) clonogenic progenitors, PDCD2 knockdown decreased the total number of colony-forming units, increased the number of colony-forming units-granulocyte-erythroid-macrophage-megakaryocyte and burst-forming unit-erythroid primitive colonies, and decreased the number of burst-forming unit-erythroid mature colonies. Similar results were observed in K562 cells, suggesting that PDCD2 is important for HPC differentiation and/or survival, and for erythroid lineage commitment. Furthermore, 12-O-tetradecanoyl-phorbol-13-acetate-induced megakaryocytic differentiation and proliferation of K562 cells was not affected by PDCD2 knockdown. In contrast, arabinofuranosylcytosine-induced erythroid differentiation of K562 cells was significantly reduced with PDCD2 knockdown, with no effect on cell proliferation. The effects of PDCD2 knockdown were attributed to a cell cycle arrest at G(0)/G(1), along with increased messenger RNA expression of early progenitor factors c-MYB and GATA-2, and decreased expression of erythroid factors GATA-1, EpoR, and ?-globin. We conclude that PDCD2 loss of function(s) impedes erythroid differentiation by inducing cell cycle arrest and increasing expression of early hematopoietic progenitor factors. These findings suggest that PDCD2 has a novel regulatory role in human hematopoiesis and is essential for erythroid development.

Project description:Abstract BACKGROUND Most patients with GBM & an unmethylated O-6-methylguanine-DNA methylase (MGMT) gene promoter, have a poor prognosis with approximately 20% of patients surviving to 2 years. Poor prognosis is likely related to factors including a highly immunosuppressive tumor microenvironment (TME). The TME in GBM is mainly composed of tumor associated macrophages (TAMs) & microglia. A subset of tumor-infiltrating macrophages characterized by expression of the angiopoietin receptor Tie2 (TEMs) have features of M2-TAMs, promote tumor angiogenesis & are infrequently found in normal organs. Tie2 is significantly upregulated upon homing to tumors. Gene therapy technology has allowed TEMs to be used as carriers for the local and tumor restricted release of interferon-α (IFN). IFN has antitumor effects, inhibits angiogenesis & modulates the immune system. Cell-based delivery of IFN into the TME by TEMs is expected to provide efficacy, taking advantage of pleiotropic anti-tumor effects & avoiding tolerability issues associated with systemic IFN treatment. We are currently conducting a Phase I/IIa clinical study in Milan (INCB & OSR) to evaluate this therapeutic approach (Temferon) in 21 patients with GBM & unmethylated MGMT promoter (EudraCT Number 2018-001404-11). Eligible patients are identified immediately after first surgical resection. After screening, harvesting of HSPCs occurs followed by 6 weeks of radiotherapy. Non-myeloablative conditioning consists of BCNU & thiotepa followed by administration of non-manipulated HSPCs and Temferon. RESULTS In Part A of the study, 3 cohorts of 3 patients will receive escalating doses of Temferon. After Part A, a single dose of Temferon will be studied in a further 12 patients (Part B). Criteria for study eligibility are the same for both Part A and Part B. Part A is ongoing with the first 2 patients recruited (June 2019) and Temferon is scheduled for administration. An update on the status and progress of the study will be provided.

Dataset Information

Knockdown of HPRT for selection of genetically modified human hematopoietic progenitor cells.

Publications

Knockdown of HPRT for selection of genetically modified human hematopoietic progenitor cells.

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