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Hays A, Islam R, Matys K, Williams D. Best Practices in qPCR and dPCR Validation in Regulated Bioanalytical Laboratories. AAPS J 2022; 24:36. [PMID: 35194700 DOI: 10.1208/s12248-022-00686-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 01/24/2022] [Indexed: 11/30/2022] Open
Affiliation(s)
- Amanda Hays
- BioAgilytix Labs, 2300 Englert Drive, Durham, NC, 27713, USA.
| | | | | | - Dave Williams
- BioAgilytix Labs, 2300 Englert Drive, Durham, NC, 27713, USA
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2
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Correction of β-thalassemia by CRISPR/Cas9 editing of the α-globin locus in human hematopoietic stem cells. Blood Adv 2021; 5:1137-1153. [PMID: 33635334 DOI: 10.1182/bloodadvances.2020001996] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 01/04/2021] [Indexed: 12/22/2022] Open
Abstract
β-thalassemias (β-thal) are a group of blood disorders caused by mutations in the β-globin gene (HBB) cluster. β-globin associates with α-globin to form adult hemoglobin (HbA, α2β2), the main oxygen-carrier in erythrocytes. When β-globin chains are absent or limiting, free α-globins precipitate and damage cell membranes, causing hemolysis and ineffective erythropoiesis. Clinical data show that severity of β-thal correlates with the number of inherited α-globin genes (HBA1 and HBA2), with α-globin gene deletions having a beneficial effect for patients. Here, we describe a novel strategy to treat β-thal based on genome editing of the α-globin locus in human hematopoietic stem/progenitor cells (HSPCs). Using CRISPR/Cas9, we combined 2 therapeutic approaches: (1) α-globin downregulation, by deleting the HBA2 gene to recreate an α-thalassemia trait, and (2) β-globin expression, by targeted integration of a β-globin transgene downstream the HBA2 promoter. First, we optimized the CRISPR/Cas9 strategy and corrected the pathological phenotype in a cellular model of β-thalassemia (human erythroid progenitor cell [HUDEP-2] β0). Then, we edited healthy donor HSPCs and demonstrated that they maintained long-term repopulation capacity and multipotency in xenotransplanted mice. To assess the clinical potential of this approach, we next edited β-thal HSPCs and achieved correction of α/β globin imbalance in HSPC-derived erythroblasts. As a safer option for clinical translation, we performed editing in HSPCs using Cas9 nickase showing precise editing with no InDels. Overall, we described an innovative CRISPR/Cas9 approach to improve α/β globin imbalance in thalassemic HSPCs, paving the way for novel therapeutic strategies for β-thal.
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Simantirakis E, Tsironis I, Vassilopoulos G. FV Vectors as Alternative Gene Vehicles for Gene Transfer in HSCs. Viruses 2020; 12:E332. [PMID: 32204324 PMCID: PMC7150843 DOI: 10.3390/v12030332] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 03/08/2020] [Accepted: 03/15/2020] [Indexed: 12/19/2022] Open
Abstract
Hematopoietic Stem Cells (HSCs) are a unique population of cells, capable of reconstituting the blood system of an organism through orchestrated self-renewal and differentiation. They play a pivotal role in stem cell therapies, both autologous and allogeneic. In the field of gene and cell therapy, HSCs, genetically modified or otherwise, are used to alleviate or correct a genetic defect. In this concise review, we discuss the use of SFVpsc_huHSRV.13, formerly known as Prototype Foamy Viral (PFV or FV) vectors, as vehicles for gene delivery in HSCs. We present the properties of the FV vectors that make them ideal for HSC delivery vehicles, we review their record in HSC gene marking studies and their potential as therapeutic vectors for monogenic disorders in preclinical animal models. FVs are a safe and efficient tool for delivering genes in HSCs compared to other retroviral gene delivery systems. Novel technological advancements in their production and purification in closed systems, have allowed their production under cGMP compliant conditions. It may only be a matter of time before they find their way into the clinic.
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Affiliation(s)
- Emmanouil Simantirakis
- Gene Therapy Lab, Biomedical Research Foundation of the Academy of Athens, Division of Genetics and Gene Therapy, Basic Research II, 11527 Athens, Greece; (E.S.); (I.T.)
| | - Ioannis Tsironis
- Gene Therapy Lab, Biomedical Research Foundation of the Academy of Athens, Division of Genetics and Gene Therapy, Basic Research II, 11527 Athens, Greece; (E.S.); (I.T.)
| | - George Vassilopoulos
- Gene Therapy Lab, Biomedical Research Foundation of the Academy of Athens, Division of Genetics and Gene Therapy, Basic Research II, 11527 Athens, Greece; (E.S.); (I.T.)
- Division of Hematology, University of Thessaly Medical School, 41500 Larissa, Greece
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4
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Abstract
Sickle cell disease is the most prevalent monogenic disorder worldwide and curative therapies are limited to hematopoietic stem cell transplant to the few with matched donors. Gene therapy has curative potential, whereby autologous hematopoietic stem cells are genetically modified and transplanted, which would not be limited by matched donors, resulting in 1-time, life-long correction devoid of immune side effects. Significant progress has been made to clinically translate gene therapy for sickle cell disease using lentivirus vectors carrying antisickling genes. This review focuses on the current state of the field, factors that determine clinical success, gene editing, and future prospects.
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Affiliation(s)
- Rajeswari Jayavaradhan
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Disease Institute (CBDI), Cincinnati Children's Hospital Medical Center (CCHMC), Mail Location 7013, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Pathobiology and Molecular Medicine Graduate Program, Mail Location: 0529, 231 Albert Sabin Way, Cincinnati, OH 45267-0529, USA
| | - Punam Malik
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Disease Institute (CBDI), Cincinnati Children's Hospital Medical Center (CCHMC), Mail Location 7013, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Pathobiology and Molecular Medicine Graduate Program, Mail Location: 0529, 231 Albert Sabin Way, Cincinnati, OH 45267-0529, USA.
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5
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Foamy Virus Vector Carries a Strong Insulator in Its Long Terminal Repeat Which Reduces Its Genotoxic Potential. J Virol 2017; 92:JVI.01639-17. [PMID: 29046446 DOI: 10.1128/jvi.01639-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 09/29/2017] [Indexed: 12/11/2022] Open
Abstract
Strong viral enhancers in gammaretrovirus vectors have caused cellular proto-oncogene activation and leukemia, necessitating the use of cellular promoters in "enhancerless" self-inactivating integrating vectors. However, cellular promoters result in relatively low transgene expression, often leading to inadequate disease phenotype correction. Vectors derived from foamy virus, a nonpathogenic retrovirus, show higher preference for nongenic integrations than gammaretroviruses/lentiviruses and preferential integration near transcriptional start sites, like gammaretroviruses. We found that strong viral enhancers/promoters placed in foamy viral vectors caused extremely low immortalization of primary mouse hematopoietic stem/progenitor cells compared to analogous gammaretrovirus/lentivirus vectors carrying the same enhancers/promoters, an effect not explained solely by foamy virus' modest insertional site preference for nongenic regions compared to gammaretrovirus/lentivirus vectors. Using CRISPR/Cas9-mediated targeted insertion of analogous proviral sequences into the LMO2 gene and then measuring LMO2 expression, we demonstrate a sequence-specific effect of foamy virus, independent of insertional bias, contributing to reduced genotoxicity. We show that this effect is mediated by a 36-bp insulator located in the foamy virus long terminal repeat (LTR) that has high-affinity binding to the CCCTC-binding factor. Using our LMO2 activation assay, LMO2 expression was significantly increased when this insulator was removed from foamy virus and significantly reduced when the insulator was inserted into the lentiviral LTR. Our results elucidate a mechanism underlying the low genotoxicity of foamy virus, identify a novel insulator, and support the use of foamy virus as a vector for gene therapy, especially when strong enhancers/promoters are required.IMPORTANCE Understanding the genotoxic potential of viral vectors is important in designing safe and efficacious vectors for gene therapy. Self-inactivating vectors devoid of viral long-terminal-repeat enhancers have proven safe; however, transgene expression from cellular promoters is often insufficient for full phenotypic correction. Foamy virus is an attractive vector for gene therapy. We found foamy virus vectors to be remarkably less genotoxic, well below what was expected from their integration site preferences. We demonstrate that the foamy virus long terminal repeats contain an insulator element that binds CCCTC-binding factor and reduces its insertional genotoxicity. Our study elucidates a mechanism behind the low genotoxic potential of foamy virus, identifies a unique insulator, and supports the use of foamy virus as a vector for gene therapy.
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Spannaus R, Miller C, Lindemann D, Bodem J. Purification of foamy viral particles. Virology 2017; 506:28-33. [PMID: 28314126 DOI: 10.1016/j.virol.2017.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 11/18/2022]
Abstract
Foamy viruses are non-pathogenic retroviruses and represent a tool for vector development. For gene therapy applications and for analyses of viral protein composition infectious particles need to be purified, which has been difficult for foamy viruses in the past. Here, we describe a novel, simple, and fast purification method for prototype foamy viruses with high purity using size exclusion and affinity chromatography. More than 99,9% of the contaminating proteins were removed. The purified viruses were used to determine the amount of the incorporated Pol protein relative to Gag. The determined Gag to Pol PR-RT ratio of 30:1 confirmed previous studies suggesting FV virions encapsidate fewer number of Pol molecules than orthoretroviruses.
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Affiliation(s)
- Ralf Spannaus
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Germany
| | - Christina Miller
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Germany
| | - Dirk Lindemann
- Institut für Virologie, Technische Universität Dresden, Germany
| | - Jochen Bodem
- Institut für Virologie und Immunbiologie, Julius-Maximilians-Universität Würzburg, Germany.
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Saliba AN, Alameddine RS, Harb AR, Taher AT. Globin gene regulation for treating β-thalassemias: progress, obstacles and future. Expert Opin Orphan Drugs 2015. [DOI: 10.1517/21678707.2015.1074071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Chandrakasan S, Malik P. Gene therapy for hemoglobinopathies: the state of the field and the future. Hematol Oncol Clin North Am 2014; 28:199-216. [PMID: 24589262 DOI: 10.1016/j.hoc.2013.12.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
After nearly two decades of struggle, gene therapy for hemoglobinopathies using vectors carrying β or γ-globin gene has finally reached the clinical doorsteps. This was made possible by advances made in our understanding of critical regulatory elements required for high level of globin gene expression and improved gene transfer vectors and methodologies. Development of gene editing technologies and reprogramming somatic cells for regenerative medicine holds the promise of genetic correction of hemoglobinopathies in the future. This article will review the state of the field and the upcoming technologies that will allow genetic therapeutic correction of hemoglobinopathies.
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Affiliation(s)
- Shanmuganathan Chandrakasan
- Division of Hematology, Oncology and Bone Marrow Transplant, Cancer and Blood Disease Institute (CBDI), Cincinnati Children's Hospital Medical Center (CCHMC), 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Punam Malik
- Division of Experimental Hematology/Cancer Biology, Cincinnati Children's Research Foundation, Cancer and Blood Institute (CBDI), Cincinnati Children's Hospital Medical Center (CCHMC), 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Division of Hematology, Cincinnati Children's Research Foundation, Cancer and Blood Institute (CBDI), Cincinnati Children's Hospital Medical Center (CCHMC), 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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Gene therapy model of X-linked severe combined immunodeficiency using a modified foamy virus vector. PLoS One 2013; 8:e71594. [PMID: 23990961 PMCID: PMC3749225 DOI: 10.1371/journal.pone.0071594] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 07/08/2013] [Indexed: 01/24/2023] Open
Abstract
X-linked severe combined immunodeficiency (SCID-X1) is an inherited genetic immunodeficiency associated with mutations in the common cytokine receptor γ chain (γc) gene, and characterized by a complete defect of T and natural killer (NK) cells. Gene therapy for SCID-X1 using conventional retroviral (RV) vectors carrying the γc gene results in the successful reconstitution of T cell immunity. However, the high incidence of vector-mediated T cell leukemia, caused by vector insertion near or within cancer-related genes has been a serious problem. In this study, we established a gene therapy model of mouse SCID-X1 using a modified foamy virus (FV) vector expressing human γc. Analysis of vector integration in a human T cell line demonstrated that the FV vector integration sites were significantly less likely to be located within or near transcriptional start sites than RV vector integration sites. To evaluate the therapeutic efficacy, bone marrow cells from γc-knockout (γc-KO) mice were infected with the FV vector and transplanted into γc-KO mice. Transplantation of the FV-treated cells resulted in the successful reconstitution of functionally active T and B cells. These data suggest that FV vectors can be effective and may be safer than conventional RV vectors for gene therapy for SCID-X1.
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Long-term follow-up of foamy viral vector-mediated gene therapy for canine leukocyte adhesion deficiency. Mol Ther 2013; 21:964-72. [PMID: 23531552 DOI: 10.1038/mt.2013.34] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The development of leukemia following gammaretroviral vector-mediated gene therapy for X-linked severe combined immunodeficiency disease and chronic granulomatous disease (CGD) has emphasized the need for long-term follow-up in animals treated with hematopoietic stem cell gene therapy. In this study, we report the long-term follow-up (4-7 years) of four dogs with canine leukocyte adhesion deficiency (CLAD) treated with foamy viral (FV) vector-mediated gene therapy. All four CLAD dogs previously received nonmyeloablative conditioning with 200 cGy total body irradiation followed by infusion of autologous, CD34(+) hematopoietic stem cells transduced by a FV vector expressing canine CD18 from an internal Murine Stem Cell Virus (MSCV) promoter. CD18(+) leukocyte levels were >2% following infusion of vector-transduced cells leading to ongoing reversal of the CLAD phenotype for >4 years. There was no clinical development of lymphoid or myeloid leukemia in any of the four dogs and integration site analysis did not reveal insertional oncogenesis. These results showing disease correction/amelioration of disease in CLAD without significant adverse events provide support for the use of a FV vector to treat children with leukocyte adhesion deficiency type 1 (LAD-1) in a human gene therapy clinical trial.
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Verhoeyen E. Advances in foamy virus vector technology and disease correction could speed the path to clinical application. Mol Ther 2012; 20:1105-7. [PMID: 22652999 DOI: 10.1038/mt.2012.97] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Els Verhoeyen
- INSERM U758, Human Virology Laboratory, EVIR, Lyon, France.
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