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Marker-free co-selection for successive rounds of prime editing in human cells. Nat Commun 2022; 13:5909. [PMID: 36207338 PMCID: PMC9546848 DOI: 10.1038/s41467-022-33669-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 09/27/2022] [Indexed: 11/18/2022] Open
Abstract
Prime editing enables the introduction of precise point mutations, small insertions, or short deletions without requiring donor DNA templates. However, efficiency remains a key challenge in a broad range of human cell types. In this work, we design a robust co-selection strategy through coediting of the ubiquitous and essential sodium/potassium pump (Na+/K+ ATPase). We readily engineer highly modified pools of cells and clones with homozygous modifications for functional studies with minimal pegRNA optimization. This process reveals that nicking the non-edited strand stimulates multiallelic editing but often generates tandem duplications and large deletions at the target site, an outcome dictated by the relative orientation of the protospacer adjacent motifs. Our approach streamlines the production of cell lines with multiple genetic modifications to create cellular models for biological research and lays the foundation for the development of cell-type specific co-selection strategies. Prime editing enables the introduction of precise point mutations, small insertions, or short deletions without requiring donor DNA templates. Here the authors develop a co-selection strategy to facilitate prime editing in human cells and provide design principles to prevent the formation of undesired editing byproducts at the target site.
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Sheikh S, Ernst D, Keating A. Prodrugs and prodrug-activated systems in gene therapy. Mol Ther 2021; 29:1716-1728. [PMID: 33831557 PMCID: PMC8116605 DOI: 10.1016/j.ymthe.2021.04.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/06/2021] [Accepted: 04/02/2021] [Indexed: 12/11/2022] Open
Abstract
The inclusion of genes that control cell fate (so-called suicide, or kill-switch, genes) into gene therapy vectors is based on a compelling rationale for the safe and selective elimination of aberrant transfected cells. Prodrug-activated systems were developed in the 1980s and 1990s and rely on the enzymatic conversion of non-active prodrugs to active metabolites that lead to cell death. Although considerable effort and ingenuity has gone into vector design for gene therapy, less attention has been directed at the efficacy or associated adverse effects of the prodrug systems employed. In this review, we discuss prodrug systems employed in clinical trials and consider their role in the field of gene therapy. We highlight potential drawbacks associated with the use of specific prodrugs, such as systemic toxicity of the activated compound, the paucity of data on biodistribution of prodrugs, bystander effects, and destruction of genetically modified cells, and how these can inform future advances in cell therapies.
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Affiliation(s)
- Semira Sheikh
- Princess Margaret Cancer Centre, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada.
| | - Daniel Ernst
- Krembil Research Institute, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada
| | - Armand Keating
- Princess Margaret Cancer Centre, Toronto, ON, Canada; Krembil Research Institute, Toronto, ON, Canada; Schroeder Arthritis Institute, Toronto, ON, Canada; University of Toronto, Toronto, ON, Canada.
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Byambaa S, Uosaki H, Ohmori T, Hara H, Endo H, Nureki O, Hanazono Y. Non-viral ex vivo genome-editing in mouse bona fide hematopoietic stem cells with CRISPR/Cas9. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 20:451-462. [PMID: 33614821 PMCID: PMC7873578 DOI: 10.1016/j.omtm.2021.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 01/06/2021] [Indexed: 12/26/2022]
Abstract
We conducted two lines of genome-editing experiments of mouse hematopoietic stem cells (HSCs) with the clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR-associated protein 9 (Cas9). First, to evaluate the genome-editing efficiency in mouse bona fide HSCs, we knocked out integrin alpha 2b (Itga2b) with Cas9 ribonucleoprotein (Cas9/RNP) and performed serial transplantation in mice. The knockout efficiency was estimated at approximately 15%. Second, giving an example of X-linked severe combined immunodeficiency (X-SCID) as a target genetic disease, we showed a proof-of-concept of universal gene correction, allowing rescue of most of X-SCID mutations, in a completely non-viral setting. We inserted partial cDNA of interleukin-2 receptor gamma chain (Il2rg) into intron 1 of Il2rg via non-homologous end-joining (NHEJ) with Cas9/RNP and a homology-independent targeted integration (HITI)-based construct. Repaired HSCs reconstituted T lymphocytes and thymuses in SCID mice. Our results show that a non-viral genome-editing of HSCs with CRISPR/Cas9 will help cure genetic diseases.
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Affiliation(s)
- Suvd Byambaa
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Hideki Uosaki
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Tsukasa Ohmori
- Division of Medical Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Hiromasa Hara
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Hitoshi Endo
- Division of Functional Biochemistry, Department of Biochemistry, School of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Yutaka Hanazono
- Division of Regenerative Medicine, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
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Lin D, Scheller SH, Robinson MM, Izadpanah R, Alt EU, Braun SE. Increased Efficiency for Biallelic Mutations of the CCR5 Gene by CRISPR-Cas9 Using Multiple Guide RNAs As a Novel Therapeutic Option for Human Immunodeficiency Virus. CRISPR J 2021; 4:92-103. [PMID: 33616448 PMCID: PMC8713505 DOI: 10.1089/crispr.2020.0019] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
CCR5 is a coreceptor of human immunodeficiency virus type 1 (HIV-1). Transplantation of hematopoietic stem cells homozygous for a 32-bp deletion in CCR5 resulted in a loss of detectable HIV-1 in two patients, suggesting that genetic strategies to knockout CCR5 expression would be a promising gene therapy approach for HIV-1-infected patients. In this study, we targeted CCR5 by CRISPR-Cas9 with a single-guide (sgRNA) and observed 35% indel frequency. When we expressed hCas9 and two gRNAs, the Surveyor assay showed that Cas9-mediated cleavage was increased by 10% with two sgRNAs. Genotype analysis on individual clones showed 11 of 13 carried biallelic mutations, where 4 clones had frameshift (FS) mutations. Taken together, these results indicate that the efficiency of biallelic FS mutations and the knockout of the CCR5 necessary to prevent viral replication were significantly increased with two sgRNAs. These studies demonstrate the knockout of CCR5 and the potential for translational development.
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Affiliation(s)
- Dong Lin
- Applied Stem Cell Laboratory,
Medicine/Heart and Vascular Institute, Tulane National Primate Research Center,
New Orleans, Louisiana, USA
- Department of Surgery, Tulane University
Health Science Center, New Orleans, Louisiana, USA
| | - Stefan H. Scheller
- Applied Stem Cell Laboratory,
Medicine/Heart and Vascular Institute, Tulane National Primate Research Center,
New Orleans, Louisiana, USA
| | - Madeline M. Robinson
- Applied Stem Cell Laboratory,
Medicine/Heart and Vascular Institute, Tulane National Primate Research Center,
New Orleans, Louisiana, USA
| | - Reza Izadpanah
- Applied Stem Cell Laboratory,
Medicine/Heart and Vascular Institute, Tulane National Primate Research Center,
New Orleans, Louisiana, USA
- Department of Surgery, Tulane University
Health Science Center, New Orleans, Louisiana, USA
| | - Eckhard U. Alt
- Applied Stem Cell Laboratory,
Medicine/Heart and Vascular Institute, Tulane National Primate Research Center,
New Orleans, Louisiana, USA
- Isar Klinikum Munich, Munich,
Germany
| | - Stephen E. Braun
- Applied Stem Cell Laboratory,
Medicine/Heart and Vascular Institute, Tulane National Primate Research Center,
New Orleans, Louisiana, USA
- Department of Pharmacology, Tulane
University Health Science Center, New Orleans, Louisiana, USA
- Division of Immunology, Tulane National
Primate Research Center, Covington, Louisiana, USA
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Humbert O, Samuelson C, Kiem HP. CRISPR/Cas9 for the treatment of haematological diseases: a journey from bacteria to the bedside. Br J Haematol 2020; 192:33-49. [PMID: 32506752 DOI: 10.1111/bjh.16807] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/07/2020] [Accepted: 05/09/2020] [Indexed: 12/26/2022]
Abstract
Genome editing therapies represent a significant advancement in next-generation, precision medicine for the management of haematological diseases, and CRISPR/Cas9 has to date been the most successful implementation platform. From discovery in bacteria and archaea over three decades ago, through intensive basic research and pre-clinical development phases involving the modification of therapeutically relevant cell types, CRISPR/Cas9 genome editing is now being investigated in ongoing clinic trials. Despite the widespread enthusiasm brought by this new technology, significant challenges remain before genome editing can be routinely recommended and implemented in the clinic. These include risks of genotoxicity resulting from off-target DNA cleavage or chromosomal rearrangement, and suboptimal efficacy of homology-directed repair editing strategies, which thus limit therapeutic options. Practical hurdles such as high costs and inaccessibility to patients outside specialised centres must also be addressed. Future improvements in this rapidly developing field should circumvent current limitations with novel editing platforms and with the simplification of clinical protocols using in vivo delivery of editing reagents.
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Affiliation(s)
| | | | - Hans-Peter Kiem
- Fred Hutchinson Cancer Research Center, Seattle, WA, USA.,University of Washington School of Medicine, Seattle, WA, USA
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Bone Marrow Homing and Engraftment Defects of Human Hematopoietic Stem and Progenitor Cells. Mediterr J Hematol Infect Dis 2017; 9:e2017032. [PMID: 28512561 PMCID: PMC5419183 DOI: 10.4084/mjhid.2017.032] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 03/18/2017] [Indexed: 12/31/2022] Open
Abstract
Homing of hematopoietic stem cells (HSC) to their microenvironment niches in the bone marrow is a complex process with a critical role in repopulation of the bone marrow after transplantation. This active process allows for migration of HSC from peripheral blood and their successful anchoring in bone marrow before proliferation. The process of engraftment starts with the onset of proliferation and must, therefore, be functionally dissociated from the former process. In this overview, we analyze the characteristics of stem cells (SCs) with particular emphasis on their plasticity and ability to find their way home to the bone marrow. We also address the problem of graft failure which remains a significant contributor to morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Within this context, we discuss non-malignant and malignant hematological disorders treated with reduced-intensity conditioning regimens or grafts from human leukocyte antigen (HLA)-mismatched donors.
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