1
|
Luo Y, Frederick A, Martin JM, Scaria A, Cheng SH, Armentano D, Wadsworth SC, Vincent KA. AAVS1-Targeted Plasmid Integration in AAV Producer Cell Lines. Hum Gene Ther Methods 2017; 28:124-138. [PMID: 28504553 DOI: 10.1089/hgtb.2016.158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adeno-associated virus (AAV) producer cell lines are created via transfection of HeLaS3 cells with a single plasmid containing three components (the vector sequence, the AAV rep and cap genes, and a selectable marker gene). As this plasmid contains both the cis (Rep binding sites) and trans (Rep protein encoded by the rep gene) elements required for site-specific integration, it was predicted that plasmid integration might occur within the AAVS1 locus on human chromosome 19 (chr19). The objective of this study was to investigate whether integration in AAVS1 might be correlated with vector yield. Plasmid integration sites within several independent cell lines were assessed via Southern, fluorescence in situ hybridization (FISH) and PCR analyses. In the Southern analyses, the presence of fragments detected by both rep- and AAVS1-specific probes suggested that for several mid- and high-producing lines, plasmid DNA had integrated into the AAVS1 locus. Analysis with puroR and AAVS1-specific probes suggested that integration in AAVS1 was a more widespread phenomenon. High-producing AAV2-secreted alkaline phosphatase (SEAP) lines (masterwell 82 [MW82] and MW278) were evaluated via FISH using probes specific for the plasmid, AAVS1, and a chr19 marker. FISH analysis detected two plasmid integration sites in MW278 (neither in AAVS1), while a total of three sites were identified in MW82 (two in AAVS1). An inverse PCR assay confirmed integration within AAVS1 for several mid- and high-producing lines. In summary, the FISH, Southern, and PCR data provide evidence of site-specific integration of the plasmid within AAVS1 in several AAV producer cell lines. The data also suggest that integration in AAVS1 is a general phenomenon that is not necessarily restricted to high producers. The results also suggest that plasmid integration within the AAVS1 locus is not an absolute requirement for a high vector yield.
Collapse
Affiliation(s)
- Yuxia Luo
- 1 Sanofi Genzyme , Framingham, Massachusetts
| | | | | | | | | | | | | | | |
Collapse
|
2
|
Tsukahara T, Iwase N, Kawakami K, Iwasaki M, Yamamoto C, Ohmine K, Uchibori R, Teruya T, Ido H, Saga Y, Urabe M, Mizukami H, Kume A, Nakamura M, Brentjens R, Ozawa K. The Tol2 transposon system mediates the genetic engineering of T-cells with CD19-specific chimeric antigen receptors for B-cell malignancies. Gene Ther 2014; 22:209-15. [PMID: 25427612 DOI: 10.1038/gt.2014.104] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 09/29/2014] [Accepted: 10/21/2014] [Indexed: 01/26/2023]
Abstract
Engineered T-cell therapy using a CD19-specific chimeric antigen receptor (CD19-CAR) is a promising strategy for the treatment of advanced B-cell malignancies. Gene transfer of CARs to T-cells has widely relied on retroviral vectors, but transposon-based gene transfer has recently emerged as a suitable nonviral method to mediate stable transgene expression. The advantages of transposon vectors compared with viral vectors include their simplicity and cost-effectiveness. We used the Tol2 transposon system to stably transfer CD19-CAR into human T-cells. Normal human peripheral blood lymphocytes were co-nucleofected with the Tol2 transposon donor plasmid carrying CD19-CAR and the transposase expression plasmid and were selectively propagated on NIH3T3 cells expressing human CD19. Expanded CD3(+) T-cells with stable and high-level transgene expression (~95%) produced interferon-γ upon stimulation with CD19 and specifically lysed Raji cells, a CD19(+) human B-cell lymphoma cell line. Adoptive transfer of these T-cells suppressed tumor progression in Raji tumor-bearing Rag2(-/-)γc(-/-) immunodeficient mice compared with control mice. These results demonstrate that the Tol2 transposon system could be used to express CD19-CAR in genetically engineered T-cells for the treatment of refractory B-cell malignancies.
Collapse
Affiliation(s)
- T Tsukahara
- 1] Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan [2] Division of Immuno-Gene and Cell Therapy (Takara Bio), Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - N Iwase
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - K Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - M Iwasaki
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - C Yamamoto
- 1] Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan [2] Division of Hematology, Department of Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - K Ohmine
- 1] Division of Immuno-Gene and Cell Therapy (Takara Bio), Jichi Medical University, Shimotsuke, Tochigi, Japan [2] Division of Hematology, Department of Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - R Uchibori
- 1] Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan [2] Division of Immuno-Gene and Cell Therapy (Takara Bio), Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - T Teruya
- Division of Immuno-Gene and Cell Therapy (Takara Bio), Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - H Ido
- Division of Immuno-Gene and Cell Therapy (Takara Bio), Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - Y Saga
- 1] Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan [2] Department of Obstetrics and Gynecology, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - M Urabe
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - H Mizukami
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - A Kume
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - M Nakamura
- Human Gene Sciences Center, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - R Brentjens
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - K Ozawa
- 1] Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan [2] Division of Immuno-Gene and Cell Therapy (Takara Bio), Jichi Medical University, Shimotsuke, Tochigi, Japan [3] Division of Hematology, Department of Medicine, Jichi Medical University, Shimotsuke, Tochigi, Japan
| |
Collapse
|
3
|
Martin J, Frederick A, Luo Y, Jackson R, Joubert M, Sol B, Poulin F, Pastor E, Armentano D, Wadsworth S, Vincent K. Generation and characterization of adeno-associated virus producer cell lines for research and preclinical vector production. Hum Gene Ther Methods 2013; 24:253-69. [PMID: 23848282 DOI: 10.1089/hgtb.2013.046] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adeno-associated virus (AAV) producer cell lines represent an effective method for large-scale production of AAV vectors. We set out to evaluate and characterize the use of an abbreviated protocol to generate "masterwells" (MWs; a nonclonal cell population) as a platform for research and preclinical vector production. In this system, a single plasmid containing three components, the vector sequence, the AAV rep, and cap genes, and a selectable marker gene is stably transfected into HeLaS3 cells. Producer cell lines generating an AAV2 vector expressing a secreted form of human placental alkaline phosphatase (SEAP) have been created. Several MWs showed vector yields in the 5×10(4) to 2×10(5) DNase-resistant particles/cell range, and the productivity was stable over >60 population doublings. Integrated plasmid copy number in three high-producing MWs ranged from approximately 12 to 50; copies were arranged in a head-to-tail configuration. Upon infection with adenovirus, rep/cap copy number was amplified approximately 100-fold and high yield appeared to be dependent on the extent of amplification. Rep/cap gene expression and vector packaging both reached a peak at 48 hr postinfection. AAV2-SEAP vector was produced in 1-liter shaker culture and purified for assessment of vector quality and potency. The data showed that the majority of the capsids from the MWs contained vector DNA (≥70%) and that purified vector was free of replication-competent AAV. In vitro and in vivo analyses demonstrated that potency of the producer cell-derived vector was comparable to vector generated via the standard transfection method.
Collapse
Affiliation(s)
- John Martin
- Genzyme, a Sanofi company , Framingham, MA 01701-9322, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
4
|
Lisowski L, Lau A, Wang Z, Zhang Y, Zhang F, Grompe M, Kay MA. Ribosomal DNA integrating rAAV-rDNA vectors allow for stable transgene expression. Mol Ther 2012; 20:1912-23. [PMID: 22990671 DOI: 10.1038/mt.2012.164] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Although recombinant adeno-associated virus (rAAV) vectors are proving to be efficacious in clinical trials, the episomal character of the delivered transgene restricts their effectiveness to use in quiescent tissues, and may not provide lifelong expression. In contrast, integrating vectors enhance the risk of insertional mutagenesis. In an attempt to overcome both of these limitations, we created new rAAV-rDNA vectors, with an expression cassette flanked by ribosomal DNA (rDNA) sequences capable of homologous recombination into genomic rDNA. We show that after in vivo delivery the rAAV-rDNA vectors integrated into the genomic rDNA locus 8-13 times more frequently than control vectors, providing an estimate that 23-39% of the integrations were specific to the rDNA locus. Moreover, a rAAV-rDNA vector containing a human factor IX (hFIX) expression cassette resulted in sustained therapeutic levels of serum hFIX even after repeated manipulations to induce liver regeneration. Because of the relative safety of integration in the rDNA locus, these vectors expand the usage of rAAV for therapeutics requiring long-term gene transfer into dividing cells.
Collapse
Affiliation(s)
- Leszek Lisowski
- Stanford University, Departments of Pediatrics and Genetics, Stanford, California 94305-5164, USA
| | | | | | | | | | | | | |
Collapse
|
5
|
Ammar I, Gogol-Döring A, Miskey C, Chen W, Cathomen T, Izsvák Z, Ivics Z. Retargeting transposon insertions by the adeno-associated virus Rep protein. Nucleic Acids Res 2012; 40:6693-712. [PMID: 22523082 PMCID: PMC3413126 DOI: 10.1093/nar/gks317] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The Sleeping Beauty (SB), piggyBac (PB) and Tol2 transposons are promising instruments for genome engineering. Integration site profiling of SB, PB and Tol2 in human cells showed that PB and Tol2 insertions were enriched in genes, whereas SB insertions were randomly distributed. We aimed to introduce a bias into the target site selection properties of the transposon systems by taking advantage of the locus-specific integration system of adeno-associated virus (AAV). The AAV Rep protein binds to Rep recognition sequences (RRSs) in the human genome, and mediates viral integration into nearby sites. A series of fusion constructs consisting of the N-terminal DNA-binding domain of Rep and the transposases or the N57 domain of SB were generated. A plasmid-based transposition assay showed that Rep/SB yielded a 15-fold enrichment of transposition at a particular site near a targeted RRS. Genome-wide insertion site analysis indicated that an approach based on interactions between the SB transposase and Rep/N57 enriched transgene insertions at RRSs. We also provide evidence of biased insertion of the PB and Tol2 transposons. This study provides a comparative insight into target site selection properties of transposons, as well as proof-of-principle for targeted chromosomal transposition by composite protein–protein and protein–DNA interactions.
Collapse
Affiliation(s)
- Ismahen Ammar
- Max Delbrück Center for Molecular Medicine, 13125 Berlin, Germany
| | | | | | | | | | | | | |
Collapse
|
6
|
Site-specific, Rep-mediated integration of the intact β-globin locus in the human erythroleukaemic cell line K562. Gene Ther 2008; 15:1372-83. [DOI: 10.1038/gt.2008.84] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
|
7
|
Ozawa K, Sato K, Oh I, Ozaki K, Uchibori R, Obara Y, Kikuchi Y, Ito T, Okada T, Urabe M, Mizukami H, Kume A. Cell and gene therapy using mesenchymal stem cells (MSCs). J Autoimmun 2008; 30:121-7. [PMID: 18249090 DOI: 10.1016/j.jaut.2007.12.008] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mesenchymal stem cells (MSCs) are considered to be a promising platform for cell and gene therapy for a variety of diseases. First, in the field of hematopoietic stem cell transplantation, there are two applications of MSCs: 1) the improvement of stem cell engrafting and the acceleration of hematopoietic reconstitution based on the hematopoiesis-supporting ability; and 2) the treatment of severe graft-versus-host disease (GVHD) based on the immunomodulatory ability. Regarding the immunosuppressive ability, we found that nitric oxide (NO) is involved in the MSC-mediated suppression of T cell proliferation. Second, tumor-bearing nude mice were injected with luciferase-expressing MSCs. An in vivo imaging analysis showed the significant accumulation of the MSCs at the site of tumors. The findings suggest that MSCs can be utilized to target metastatic tumors and to deliver anti-cancer molecules locally. As the third application, MSCs may be utilized as a cellular vehicle for protein-supplement gene therapy. When long-term transgene expression is needed, a therapeutic gene should be introduced with a minimal risk of insertional mutagenesis. To this end, site-specific integration into the AAVS1 locus on the chromosome 19 (19q13.4) by using the integration machinery of adeno-associated virus (AAV) would be particularly valuable. There will be wide-ranging applications of MSCs to frontier medical treatments in the near future.
Collapse
Affiliation(s)
- Keiya Ozawa
- Division of Hematology, Department of Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
The transient expression of mRNA coding for Rep protein from AAV facilitates targeted plasmid integration. J Gene Med 2007; 10:42-50. [DOI: 10.1002/jgm.1118] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
|
9
|
Coates CJ, Kaminski JM, Summers JB, Segal DJ, Miller AD, Kolb AF. Site-directed genome modification: derivatives of DNA-modifying enzymes as targeting tools. Trends Biotechnol 2005; 23:407-19. [PMID: 15993503 DOI: 10.1016/j.tibtech.2005.06.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 04/14/2005] [Accepted: 06/14/2005] [Indexed: 01/11/2023]
Abstract
The modification of mammalian genomes is an important goal in gene therapy and animal transgenesis. To generate stable genetic and biochemical changes, the therapeutic genes or transgenes need to be incorporated into the host genome. Ideally, the integration of the foreign gene should occur at sites that ensure their continual expression in the absence of any unwanted side effects on cellular metabolism. In this article, we discuss the opportunities provided by natural DNA-modifying enzymes, such as transposases, recombinases and integrases, to mediate the stable integration of foreign genes into host genomes. In addition, we discuss the approaches that have been taken to improve the efficiency and to modify the site-specificity of these enzymes.
Collapse
Affiliation(s)
- Craig J Coates
- Department of Entomology, Texas A&M University, College Station, TX 77843, USA
| | | | | | | | | | | |
Collapse
|
10
|
Gene therapy. NEURODEGENER DIS 2005. [DOI: 10.1017/cbo9780511544873.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
|
11
|
Glover DJ, Lipps HJ, Jans DA. Towards safe, non-viral therapeutic gene expression in humans. Nat Rev Genet 2005; 6:299-310. [PMID: 15761468 DOI: 10.1038/nrg1577] [Citation(s) in RCA: 413] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The potential dangers of using viruses to deliver and integrate DNA into host cells in gene therapy have been poignantly highlighted in recent clinical trials. Safer, non-viral gene delivery approaches have been largely ignored in the past because of their inefficient delivery and the resulting transient transgene expression. However, recent advances indicate that efficient, long-term gene expression can be achieved by non-viral means. In particular, integration of DNA can be targeted to specific genomic sites without deleterious consequences and it is possible to maintain transgenes as small episomal plasmids or artificial chromosomes. The application of these approaches to human gene therapy is gradually becoming a reality.
Collapse
Affiliation(s)
- Dominic J Glover
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Victoria 3800, Australia
| | | | | |
Collapse
|
12
|
Xie Q, Hare J, Turnigan J, Chapman MS. Large-scale production, purification and crystallization of wild-type adeno-associated virus-2. J Virol Methods 2005; 122:17-27. [PMID: 15488616 DOI: 10.1016/j.jviromet.2004.07.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Revised: 07/08/2004] [Accepted: 07/19/2004] [Indexed: 10/26/2022]
Abstract
Adeno-associated virus-2 (AAV-2) has long been recognized as a potential vector for human gene therapy. Although much progress has been made in the molecular virology of AAV-2, structural studies of AAV-2 have been hampered by the low efficiency of virus production in culture, the low purity of preparations, and the low solubility of pure virus particles in solution. Methods of larger scale AAV-2 production have been developed through adaptation to suspension culture and re-optimization of the times of infection and transfection with respect to particle production. The methods allow the purification of 10mg ( approximately 10(15) particles) of AAV-2 per preparation at approximately 99% purity as judged by SDS-PAGE. This was sufficient for the screening of conditions for the formation of diffraction-grade crystals, ultimately leading to an atomic structure for AAV-2.
Collapse
Affiliation(s)
- Qing Xie
- Kasha Laboratory of Molecular Biophysics, Florida State University, FL, USA
| | | | | | | |
Collapse
|
13
|
Abstract
The driving interest in adeno-associated virus (AAV) has been its potential as a gene delivery vector. The early observation that AAV can establish a latent infection by integrating into the host chromosome has been central to this interest. However, chromosomal integration is a two-edged sword, imparting on one hand the ability to maintain the therapeutic gene in progeny cells, and on the other hand, the risk of mutations that are deleterious to the host. A clearer understanding of the mechanism and efficiency of AAV integration, in terms of contributing viral and host-cell factors and circumstances, will provide a context in which to evaluate these potential benefits and risks. Research to date suggests that AAV integration in any context is inefficient, and that the persistence of AAV gene delivery vectors in tissues is largely attributable to episomal genomes.
Collapse
Affiliation(s)
- Douglas M McCarty
- School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
| | | | | |
Collapse
|
14
|
Ozawa K. [Development and application of gene therapy technologies]. Uirusu 2004; 54:49-57. [PMID: 15449904 DOI: 10.2222/jsv.54.49] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The success of hematopoietic stem cell gene therapy for X-linked severe combined immunodeficiency (X-SCID) was a major breakthrough in the field of gene therapy. However, two patients treated with this gene therapy developed leukemia at a later time, and retroviral vector-mediated gene transfer was considered to trigger leukemogenesis; i.e. insertional mutagenesis caused activation of LMO 2 gene, which was one step toward leukemia development. To cope with this serious problem, basic studies are required to improve the safety of retroviral vectors and to develop the method for site-specific integration of transgenes. In addition, we have to develop technologies such as selective amplifier genes (SAGs), the system for selective expansion of transduced cells, in order to obtain therapeutic efficacy of hematopoietic stem cell gene therapy in many other disorders. Moreover, clinical applications of AAV vector are promising from the standpoint of safety issue, because this vector is derived from non-pathogenic virus. AAV vector is appropriate for gene transfer into neurons, muscles, and hepatocytes. For example, gene therapy for Parkinson's disease is investigated using AAV vectors. Genetic manipulation is also one of the indispensable technologies in the field of regeneration medicine, and further promotion of basic research is important.
Collapse
Affiliation(s)
- Keiya Ozawa
- Division of Hematology, Department of Medicine, Jichi Medical School, 3311- 1 Yakushiji, Minamikawachi-machi Kawachi-gun, Tochigi 329-0498, Japan.
| |
Collapse
|
15
|
Giannoukakis N, Trucco M. Current status and prospects for gene and cell therapeutics for type 1 diabetes mellitus. Rev Endocr Metab Disord 2003; 4:369-80. [PMID: 14618022 DOI: 10.1023/a:1027306213563] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Nick Giannoukakis
- Department of Pathology and Diabetes Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | | |
Collapse
|
16
|
Urabe M, Kogure K, Kume A, Sato Y, Tobita K, Ozawa K. Positive and negative effects of adeno-associated virus Rep on AAVS1-targeted integration. J Gen Virol 2003; 84:2127-2132. [PMID: 12867644 DOI: 10.1099/vir.0.19193-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adeno-associated virus type 2 integrates preferentially into the AAVS1 locus on chromosome 19 of the human genome. It was reported previously that transfection with two plasmids, one for Rep and the other carrying a transgene flanked by inverted terminal repeats (ITRs), enables preferential integration of the latter into AAVS1. Aiming at increasing the frequency of AAVS1-specific integration, the Rep- to transgene-plasmid ratio necessary to achieve a higher frequency of site-specific integration was examined. 293 cells were co-transfected with the Rep78 plasmid and an ITR-flanked Neo gene at different ratios. G418-resistant clones were selected randomly. Extensive Southern blot analysis showed an optimum range of Rep78 expression. In that range, approximately 20 % of clones harboured the Neo gene at AAVS1. Excess Rep expression, however, resulted in 'abortive' integration of the Neo gene, a rearrangement of AAVS1 without transgene integration. Rep78 appeared to cause abortive integration more extensively than Rep68. Deleterious effects of the Rep protein on the AAVS1 locus should be considered to develop an improved AAVS1-targeted system.
Collapse
Affiliation(s)
- Masashi Urabe
- Department of Virology, Jichi Medical School, Tochigi 329-0498, Japan
- CREST, Japan Science and Technology Corporation (JST), Tochigi 329-0498, Japan
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical School, 3311-1 Yakushiji, Minami-Kawachi, Tochigi 329-0498, Japan
| | - Katsuhiro Kogure
- CREST, Japan Science and Technology Corporation (JST), Tochigi 329-0498, Japan
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical School, 3311-1 Yakushiji, Minami-Kawachi, Tochigi 329-0498, Japan
| | - Akihiro Kume
- CREST, Japan Science and Technology Corporation (JST), Tochigi 329-0498, Japan
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical School, 3311-1 Yakushiji, Minami-Kawachi, Tochigi 329-0498, Japan
| | - Yuko Sato
- Department of Intractable Diseases, Research Institute, International Medical Center of Japan, Tokyo 162-8655, Japan
| | - Kiyotake Tobita
- Department of Virology, Jichi Medical School, Tochigi 329-0498, Japan
| | - Keiya Ozawa
- CREST, Japan Science and Technology Corporation (JST), Tochigi 329-0498, Japan
- Division of Genetic Therapeutics, Center for Molecular Medicine, Jichi Medical School, 3311-1 Yakushiji, Minami-Kawachi, Tochigi 329-0498, Japan
| |
Collapse
|
17
|
Bottino R, Lemarchand P, Trucco M, Giannoukakis N. Gene- and cell-based therapeutics for type I diabetes mellitus. Gene Ther 2003; 10:875-89. [PMID: 12732873 DOI: 10.1038/sj.gt.3302015] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Type 1 diabetes mellitus, an autoimmune disorder is an attractive candidate for gene and cell-based therapy. From the use of gene-engineered immune cells to induce hyporesponsiveness to autoantigens to islet and beta cell surrogate transplants expressing immunoregulatory genes to provide a local pocket of immune privilege, these strategies have demonstrated proof of concept to the point where translational studies can be initiated. Nonetheless, along with the proof of concept, a number of important issues have been raised by the choice of vector and expression system as well as the point of intervention; prophylactic or therapeutic. An assessment of the current state of the science and potential leads to the conclusion that some strategies are ready for safety trials while others require varying degrees of technical and conceptual refinement.
Collapse
Affiliation(s)
- R Bottino
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | | | | | | |
Collapse
|