1
|
Cuypers ML, Geukens N, Hollevoet K, Declerck P, Dewilde M. Exploring the Fate of Antibody-Encoding pDNA after Intramuscular Electroporation in Mice. Pharmaceutics 2023; 15:pharmaceutics15041160. [PMID: 37111645 PMCID: PMC10146361 DOI: 10.3390/pharmaceutics15041160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 04/29/2023] Open
Abstract
DNA-based antibody therapy seeks to administer the encoding nucleotide sequence rather than the antibody protein. To further improve the in vivo monoclonal antibody (mAb) expression, a better understanding of what happens after the administration of the encoding plasmid DNA (pDNA) is required. This study reports the quantitative evaluation and localization of the administered pDNA over time and its association with corresponding mRNA levels and systemic protein concentrations. pDNA encoding the murine anti-HER2 4D5 mAb was administered to BALB/c mice via intramuscular injection followed by electroporation. Muscle biopsies and blood samples were taken at different time points (up to 3 months). In muscle, pDNA levels decreased 90% between 24 h and one week post treatment (p < 0.0001). In contrast, mRNA levels remained stable over time. The 4D5 antibody plasma concentrations reached peak levels at week two followed by a slow decrease (50% after 12 weeks, p < 0.0001). Evaluation of pDNA localization revealed that extranuclear pDNA was cleared fast, whereas the nuclear fraction remained relatively stable. This is in line with the observed mRNA and protein levels over time and indicates that only a minor fraction of the administered pDNA is ultimately responsible for the observed systemic mAb levels. In conclusion, this study demonstrates that durable expression is dependent on the nuclear uptake of the pDNA. Therefore, efforts to increase the protein levels upon pDNA-based gene therapy should focus on strategies to increase both cellular entry and migration of the pDNA into the nucleus. The currently applied methodology can be used to guide the design and evaluation of novel plasmid-based vectors or alternative delivery methods in order to achieve a robust and prolonged protein expression.
Collapse
Affiliation(s)
- Marie-Lynn Cuypers
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
| | - Nick Geukens
- PharmAbs-The KU Leuven Antibody Center, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
| | - Kevin Hollevoet
- PharmAbs-The KU Leuven Antibody Center, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
| | - Paul Declerck
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
- PharmAbs-The KU Leuven Antibody Center, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
| | - Maarten Dewilde
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
- PharmAbs-The KU Leuven Antibody Center, KU Leuven-University of Leuven, O&N II Herestraat 49 Box 820, 3000 Leuven, Belgium
| |
Collapse
|
2
|
Liedl A, Grießing J, Kretzmann JA, Dietz H. Active Nuclear Import of Mammalian Cell-Expressible DNA Origami. J Am Chem Soc 2023; 145:4946-4950. [PMID: 36828394 PMCID: PMC9999407 DOI: 10.1021/jacs.2c12733] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
DNA origami enables the creation of complex 3D shapes from genetic material. Future uses could include the delivery of genetic instructions to cells, but nuclear import remains a major barrier to gene delivery due to the impermeability of the nuclear membrane. Here we realize active nuclear import of DNA origami objects in dividing and chemically arrested mammalian cells. We developed a custom DNA origami single-strand scaffold featuring a mammalian-cell expressible reporter gene (mCherry) and multiple Simian virus 40 (SV40) derived DNA nuclear targeting sequences (DTS). Inclusion of the DTS within DNA origami rescued gene expression in arrested cells, indicating that active transport into the nucleus occurs. Our work successfully adapts mechanisms known from viruses to promote the cellular expression of genetic instructions encoded within DNA origami objects.
Collapse
Affiliation(s)
- Anna Liedl
- Department of Biosciences, School of Natural Sciences, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany.,Munich Institute of Biomedical Engineering, Technical University of Munich, Boltzmannstraße 11, 85748 Garching, Germany
| | - Johanna Grießing
- Department of Biosciences, School of Natural Sciences, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany.,Munich Institute of Biomedical Engineering, Technical University of Munich, Boltzmannstraße 11, 85748 Garching, Germany
| | - Jessica A Kretzmann
- Department of Biosciences, School of Natural Sciences, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany.,Munich Institute of Biomedical Engineering, Technical University of Munich, Boltzmannstraße 11, 85748 Garching, Germany
| | - Hendrik Dietz
- Department of Biosciences, School of Natural Sciences, Technical University of Munich, Am Coulombwall 4a, 85748 Garching, Germany.,Munich Institute of Biomedical Engineering, Technical University of Munich, Boltzmannstraße 11, 85748 Garching, Germany
| |
Collapse
|
3
|
Cepleanu-Pascu IA, Stan M, Cocioba S, Stoica I. Easy method for six-fragment Golden Gate Assembly of modular vectors. Biotechniques 2023; 74:85-99. [PMID: 36691899 DOI: 10.2144/btn-2022-0041] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Efficient cloning techniques are a requirement for synthetic biology. This study provides a simplified cloning method based on Golden Gate Assembly that can be used for rapid vector construction. The building of multiple expression vectors with customizable modules is achieved in a timely manner with minimal hands-on time by removing unnecessary steps in the workflow. The authors constructed a total of 21 mammalian episomal expression vectors and conducted a fluorescence expression comparison for different regulatory region combinations post-transfection in HEK293T and HEPG2 cells. Screening revealed that using the EF-1α promoter in combination with the bovine growth hormone polyadenylation sequence seemed to perform best in the types of cells tested compared with other variants.
Collapse
Affiliation(s)
| | - Miruna Stan
- Department of Biochemistry & Molecular Biology, Faculty of Biology, University of Bucharest, Bucharest, Romania
| | | | - Ileana Stoica
- Department of Genetics, Faculty of Biology, University of Bucharest, Bucharest, Romania
| |
Collapse
|
4
|
Non-Viral Delivery of CRISPR/Cas Cargo to the Retina Using Nanoparticles: Current Possibilities, Challenges, and Limitations. Pharmaceutics 2022; 14:pharmaceutics14091842. [PMID: 36145593 PMCID: PMC9503525 DOI: 10.3390/pharmaceutics14091842] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/25/2022] [Accepted: 08/29/2022] [Indexed: 12/13/2022] Open
Abstract
The discovery of the CRISPR/Cas system and its development into a powerful genome engineering tool have revolutionized the field of molecular biology and generated excitement for its potential to treat a wide range of human diseases. As a gene therapy target, the retina offers many advantages over other tissues because of its surgical accessibility and relative immunity privilege due to its blood–retinal barrier. These features explain the large advances made in ocular gene therapy over the past decade, including the first in vivo clinical trial using CRISPR gene-editing reagents. Although viral vector-mediated therapeutic approaches have been successful, they have several shortcomings, including packaging constraints, pre-existing anti-capsid immunity and vector-induced immunogenicity, therapeutic potency and persistence, and potential genotoxicity. The use of nanomaterials in the delivery of therapeutic agents has revolutionized the way genetic materials are delivered to cells, tissues, and organs, and presents an appealing alternative to bypass the limitations of viral delivery systems. In this review, we explore the potential use of non-viral vectors as tools for gene therapy, exploring the latest advancements in nanotechnology in medicine and focusing on the nanoparticle-mediated delivery of CRIPSR genetic cargo to the retina.
Collapse
|
5
|
Rao VB, Zhu J. Bacteriophage T4 as a nanovehicle for delivery of genes and therapeutics into human cells. Curr Opin Virol 2022; 55:101255. [PMID: 35952598 DOI: 10.1016/j.coviro.2022.101255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 07/09/2022] [Indexed: 11/18/2022]
Abstract
The ability to deliver therapeutic genes and biomolecules into a human cell and restore a defective function has been the holy grail of medicine. Adeno-associated viruses and lentiviruses have been extensively used as delivery vehicles, but their capacity is limited to one (or two) gene(s). Bacteriophages are emerging as novel vehicles for gene therapy. The large 120 × 86-nm T4 capsid allows engineering of both its surface and its interior to incorporate combinations of DNAs, RNAs, proteins, and their complexes. In vitro assembly using purified components allows customization for various applications and for individualized therapies. Its large capacity, cell-targeting capability, safety, and inexpensive manufacturing could open unprecedented new possibilities for gene, cancer, and stem cell therapies. However, efficient entry into primary human cells and intracellular trafficking are significant barriers that must be overcome by gene engineering and evolution in order to translate phage-delivery technology from bench to bedside.
Collapse
Affiliation(s)
- Venigalla B Rao
- Bacteriophage Medical Research Center, Department of Biology, The Catholic University of America, Washington, DC 20064, USA.
| | - Jingen Zhu
- Bacteriophage Medical Research Center, Department of Biology, The Catholic University of America, Washington, DC 20064, USA
| |
Collapse
|
6
|
Sachdev S, Potočnik T, Rems L, Miklavčič D. Revisiting the role of pulsed electric fields in overcoming the barriers to in vivo gene electrotransfer. Bioelectrochemistry 2022; 144:107994. [PMID: 34930678 DOI: 10.1016/j.bioelechem.2021.107994] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/15/2021] [Accepted: 11/02/2021] [Indexed: 12/21/2022]
Abstract
Gene therapies are revolutionizing medicine by providing a way to cure hitherto incurable diseases. The scientific and technological advances have enabled the first gene therapies to become clinically approved. In addition, with the ongoing COVID-19 pandemic, we are witnessing record speeds in the development and distribution of gene-based vaccines. For gene therapy to take effect, the therapeutic nucleic acids (RNA or DNA) need to overcome several barriers before they can execute their function of producing a protein or silencing a defective or overexpressing gene. This includes the barriers of the interstitium, the cell membrane, the cytoplasmic barriers and (in case of DNA) the nuclear envelope. Gene electrotransfer (GET), i.e., transfection by means of pulsed electric fields, is a non-viral technique that can overcome these barriers in a safe and effective manner. GET has reached the clinical stage of investigations where it is currently being evaluated for its therapeutic benefits across a wide variety of indications. In this review, we formalize our current understanding of GET from a biophysical perspective and critically discuss the mechanisms by which electric field can aid in overcoming the barriers. We also identify the gaps in knowledge that are hindering optimization of GET in vivo.
Collapse
Affiliation(s)
- Shaurya Sachdev
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Tjaša Potočnik
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Lea Rems
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia.
| |
Collapse
|
7
|
Transfected plasmid DNA is incorporated into the nucleus via nuclear envelope reformation at telophase. Commun Biol 2022; 5:78. [PMID: 35058555 PMCID: PMC8776997 DOI: 10.1038/s42003-022-03021-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 12/27/2021] [Indexed: 12/15/2022] Open
Abstract
AbstractDNA transfection is an important technology in life sciences, wherein nuclear entry of DNA is necessary to express exogenous DNA. Non-viral vectors and their transfection reagents are useful as safe transfection tools. However, they have no effect on the transfection of non-proliferating cells, the reason for which is not well understood. This study elucidates the mechanism through which transfected DNA enters the nucleus for gene expression. To monitor the behavior of transfected DNA, we introduce plasmid bearing lacO repeats and RFP-coding sequences into cells expressing GFP-LacI and observe plasmid behavior and RFP expression in living cells. RFP expression appears only after mitosis. Electron microscopy reveals that plasmids are wrapped with nuclear envelope (NE)‒like membranes or associated with chromosomes at telophase. The depletion of BAF, which is involved in NE reformation, delays plasmid RFP expression. These results suggest that transfected DNA is incorporated into the nucleus during NE reformation at telophase.
Collapse
|
8
|
Chu D, Nguyen A, Smith SS, Vavrušová Z, Schneider RA. Stable integration of an optimized inducible promoter system enables spatiotemporal control of gene expression throughout avian development. Biol Open 2020; 9:bio055343. [PMID: 32917762 PMCID: PMC7561481 DOI: 10.1242/bio.055343] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 08/27/2020] [Indexed: 01/18/2023] Open
Abstract
Precisely altering gene expression is critical for understanding molecular processes of embryogenesis. Although some tools exist for transgene misexpression in developing chick embryos, we have refined and advanced them by simplifying and optimizing constructs for spatiotemporal control. To maintain expression over the entire course of embryonic development we use an enhanced piggyBac transposon system that efficiently integrates sequences into the host genome. We also incorporate a DNA targeting sequence to direct plasmid translocation into the nucleus and a D4Z4 insulator sequence to prevent epigenetic silencing. We designed these constructs to minimize their size and maximize cellular uptake, and to simplify usage by placing all of the integrating sequences on a single plasmid. Following electroporation of stage HH8.5 embryos, our tetracycline-inducible promoter construct produces robust transgene expression in the presence of doxycycline at any point during embryonic development in ovo or in culture. Moreover, expression levels can be modulated by titrating doxycycline concentrations and spatial control can be achieved using beads or gels. Thus, we have generated a novel, sensitive, tunable, and stable inducible-promoter system for high-resolution gene manipulation in vivo.
Collapse
Affiliation(s)
- Daniel Chu
- Department of Orthopaedic Surgery, University of California at San Francisco, 513 Parnassus Avenue, S-1164, San Francisco, CA 94143-0514, USA
| | - An Nguyen
- Department of Orthopaedic Surgery, University of California at San Francisco, 513 Parnassus Avenue, S-1164, San Francisco, CA 94143-0514, USA
| | - Spenser S Smith
- Department of Orthopaedic Surgery, University of California at San Francisco, 513 Parnassus Avenue, S-1164, San Francisco, CA 94143-0514, USA
| | - Zuzana Vavrušová
- Department of Orthopaedic Surgery, University of California at San Francisco, 513 Parnassus Avenue, S-1164, San Francisco, CA 94143-0514, USA
| | - Richard A Schneider
- Department of Orthopaedic Surgery, University of California at San Francisco, 513 Parnassus Avenue, S-1164, San Francisco, CA 94143-0514, USA
| |
Collapse
|
9
|
Le Guen YT, Le Gall T, Midoux P, Guégan P, Braun S, Montier T. Gene transfer to skeletal muscle using hydrodynamic limb vein injection: current applications, hurdles and possible optimizations. J Gene Med 2020; 22:e3150. [PMID: 31785130 DOI: 10.1002/jgm.3150] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 11/27/2019] [Accepted: 11/27/2019] [Indexed: 11/06/2022] Open
Abstract
Hydrodynamic limb vein injection is an in vivo locoregional gene delivery method. It consists of administrating a large volume of solution containing nucleic acid constructs in a limb with both blood inflow and outflow temporarily blocked using a tourniquet. The fast, high pressure delivery allows the musculature of the whole limb to be reached. The skeletal muscle is a tissue of choice for a variety of gene transfer applications, including gene therapy for Duchenne muscular dystrophy or other myopathies, as well as for the production of antibodies or other proteins with broad therapeutic effects. Hydrodynamic limb vein delivery has been evaluated with success in a large range of animal models. It has also proven to be safe and well-tolerated in muscular dystrophy patients, thus supporting its translation to the clinic. However, some possible limitations may occur at different steps of the delivery process. Here, we have highlighted the interests, bottlenecks and potential improvements that could further optimize non-viral gene transfer following hydrodynamic limb vein injection.
Collapse
Affiliation(s)
| | - Tony Le Gall
- Univ Brest, INSERM, EFS, UMR 1078, GGB, F-29200, Brest, France
| | - Patrick Midoux
- Centre de Biophysique Moléculaire, CNRS UPR 4301, Université d'Orléans, France
| | - Philippe Guégan
- Laboratoire de chimie des polymères, Sorbonne Université, CNRS UMR 8232, UPMC Paris 06, F-75005, Paris, France
| | - Serge Braun
- AFM Telethon, 1 rue de l'Internationale, BP59, 91002 Evry, France
| | - Tristan Montier
- Univ Brest, INSERM, EFS, UMR 1078, GGB, F-29200, Brest, France.,Service de Génétique Médicale et Biologie de la Reproduction, Centre de référence des maladies rares 'Maladies neuromusculaires', CHRU de Brest, F-29200, Brest, France
| |
Collapse
|
10
|
Hamann A, Nguyen A, Pannier AK. Nucleic acid delivery to mesenchymal stem cells: a review of nonviral methods and applications. J Biol Eng 2019; 13:7. [PMID: 30675180 PMCID: PMC6339289 DOI: 10.1186/s13036-019-0140-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 01/07/2019] [Indexed: 12/13/2022] Open
Abstract
Background Mesenchymal stem cells (MSCs) are multipotent stem cells that can be isolated and expanded from many tissues, and are being investigated for use in cell therapies. Though MSC therapies have demonstrated some success, none have been FDA approved for clinical use. MSCs lose stemness ex vivo, decreasing therapeutic potential, and face additional barriers in vivo, decreasing therapeutic efficacy. Culture optimization and genetic modification of MSCs can overcome these barriers. Viral transduction is efficient, but limited by safety concerns related to mutagenicity of integrating viral vectors and potential immunogenicity of viral antigens. Nonviral delivery methods are safer, though limited by inefficiency and toxicity, and are flexible and scalable, making them attractive for engineering MSC therapies. Main text Transfection method and nucleic acid determine efficiency and expression profile in transfection of MSCs. Transfection methods include microinjection, electroporation, and nanocarrier delivery. Microinjection and electroporation are efficient, but are limited by throughput and toxicity. In contrast, a variety of nanocarriers have been demonstrated to transfer nucleic acids into cells, however nanocarrier delivery to MSCs has traditionally been inefficient. To improve efficiency, plasmid sequences can be optimized by choice of promoter, inclusion of DNA targeting sequences, and removal of bacterial elements. Instead of DNA, RNA can be delivered for rapid protein expression or regulation of endogenous gene expression. Beyond choice of nanocarrier and nucleic acid, transfection can be optimized by priming cells with media additives and cell culture surface modifications to modulate barriers of transfection. Media additives known to enhance MSC transfection include glucocorticoids and histone deacetylase inhibitors. Culture surface properties known to modulate MSC transfection include substrate stiffness and specific protein coating. If nonviral gene delivery to MSCs can be sufficiently improved, MSC therapies could be enhanced by transfection for guided differentiation and reprogramming, transplantation survival and directed homing, and secretion of therapeutics. We discuss utilized delivery methods and nucleic acids, and resulting efficiency and outcomes, in transfection of MSCs reported for such applications. Conclusion Recent developments in transfection methods, including nanocarrier and nucleic acid technologies, combined with chemical and physical priming of MSCs, may sufficiently improve transfection efficiency, enabling scalable genetic engineering of MSCs, potentially bringing effective MSC therapies to patients.
Collapse
Affiliation(s)
- Andrew Hamann
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, 231 L.W. Chase Hall, Lincoln, NE 68583-0726 USA
| | - Albert Nguyen
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, 231 L.W. Chase Hall, Lincoln, NE 68583-0726 USA
| | - Angela K Pannier
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, 231 L.W. Chase Hall, Lincoln, NE 68583-0726 USA
| |
Collapse
|
11
|
Hamann A, Broad K, Nguyen A, Pannier AK. Mechanisms of unprimed and dexamethasone-primed nonviral gene delivery to human mesenchymal stem cells. Biotechnol Bioeng 2018; 116:427-443. [PMID: 30450542 PMCID: PMC6322959 DOI: 10.1002/bit.26870] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 10/10/2018] [Accepted: 11/16/2018] [Indexed: 12/16/2022]
Abstract
Human mesenchymal stem cells (hMSCs) are under intense study for applications of cell and gene therapeutics because of their unique immunomodulatory and regenerative properties. Safe and efficient genetic modification of hMSCs could increase their clinical potential by allowing functional expression of therapeutic transgenes or control over behavior and differentiation. Viral gene delivery is efficient, but suffers from safety issues, while nonviral methods are safe, but highly inefficient, especially in hMSCs. Our lab previously demonstrated that priming cells before delivery of DNA complexes with dexamethasone (DEX), an anti‐inflammatory glucocorticoid drug, significantly increases hMSC transfection success. This work systematically investigates the mechanisms of hMSC transfection and DEX‐mediated enhancement of transfection. Our results show that hMSC transfection and its enhancement by DEX are decreased by inhibiting classical intracellular transport and nuclear import pathways, but DEX transfection priming does not increase cellular or nuclear internalization of plasmid DNA (pDNA). We also show that hMSC transgene expression is largely affected by pDNA promoter and enhancer sequence changes, but DEX‐mediated enhancement of transfection is unaffected by any pDNA sequence changes. Furthermore, DEX‐mediated transfection enhancement is not the result of increased transgene messenger RNA transcription or stability. However, DEX‐priming increases total protein synthesis by preventing hMSC apoptosis induced by transfection, resulting in increased translation of transgenic protein. DEX may also promote further enhancement of transgenic reporter enzyme activity by other downstream mechanisms. Mechanistic studies of nonviral gene delivery will inform future rationally designed technologies for safe and efficient genetic modification of clinically relevant cell types.
Collapse
Affiliation(s)
- Andrew Hamann
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Kelly Broad
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Albert Nguyen
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska
| | - Angela K Pannier
- Department of Biological Systems Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska
| |
Collapse
|
12
|
Enhancing Electrotransfection Efficiency through Improvement in Nuclear Entry of Plasmid DNA. MOLECULAR THERAPY. NUCLEIC ACIDS 2018; 11:263-271. [PMID: 29858061 PMCID: PMC5992438 DOI: 10.1016/j.omtn.2018.02.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 02/22/2018] [Accepted: 02/26/2018] [Indexed: 01/15/2023]
Abstract
The nuclear envelope is a physiological barrier to electrogene transfer. To understand different mechanisms of the nuclear entry for electrotransfected plasmid DNA (pDNA), the current study investigated how manipulation of the mechanisms could affect electrotransfection efficiency (eTE), transgene expression level (EL), and cell viability. In the investigation, cells were first synchronized at G2-M phase prior to electrotransfection so that the nuclear envelope breakdown (NEBD) occurred before pDNA entered the cells. The NEBD significantly increased the eTE and the EL while the cell viability was not compromised. In the second experiment, the cells were treated with a nuclear pore dilating agent (i.e., trans-1,2-cyclohexanediol). The treatment could increase the EL, but had only minor effects on eTE. Furthermore, the treatment was more cytotoxic, compared with the cell synchronization. In the third experiment, a nuclear targeting sequence (i.e., SV40) was incorporated into the pDNA prior to electrotransfection. The incorporation was more effective than the cell synchronization for enhancing the EL, but not the eTE, and the effectiveness was cell type dependent. Taken together, the data described above suggested that synchronization of the NEBD could be a practical approach to improving electrogene transfer in all dividing cells.
Collapse
|
13
|
Hacobian A, Hercher D. Pushing the Right Buttons: Improving Efficacy of Therapeutic DNA Vectors. TISSUE ENGINEERING PART B-REVIEWS 2017; 24:226-239. [PMID: 29264951 DOI: 10.1089/ten.teb.2017.0353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Gene therapy represents a potent therapeutical application for regenerative medicine. So far, viral and nonviral approaches suffer from major drawbacks hindering efficient gene therapeutic applicability: the immunogenicity of viral systems on the one hand, and the low gene transfer efficiency of nonviral systems on the other hand. Therefore, there is a high demand for improvements of therapeutical systems at several levels. This review summarizes different DNA vector modifications to enhance biological efficacy and efficiency of therapeutical vectors, aiming for low toxicity, high specificity, and biological efficacy-the cornerstones for successful translation of gene therapy into the clinic. We aim to provide a step-by-step instruction to optimize their vectors to achieve the desired outcome of gene therapy. Our review provides the means to either construct a potent gene therapeutic vector de novo or to specifically address a bottleneck in the chain of events mandatory for therapeutic success. Although most of the introduced techniques can be translated into different areas, this review primarily addresses improvements for applications in transient gene therapy in the field of tissue engineering.
Collapse
Affiliation(s)
- Ara Hacobian
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Department of Molecular Biology, AUVA Research Center, The Austrian Cluster for Tissue Regeneration , Vienna, Austria
| | - David Hercher
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Department of Molecular Biology, AUVA Research Center, The Austrian Cluster for Tissue Regeneration , Vienna, Austria
| |
Collapse
|
14
|
Cytoplasmic transport and nuclear import of plasmid DNA. Biosci Rep 2017; 37:BSR20160616. [PMID: 29054961 PMCID: PMC5705778 DOI: 10.1042/bsr20160616] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/13/2017] [Accepted: 10/17/2017] [Indexed: 01/04/2023] Open
Abstract
Productive transfection and gene transfer require not simply the entry of DNA into cells and subsequent transcription from an appropriate promoter, but also a number of intracellular events that allow the DNA to move from the extracellular surface of the cell into and through the cytoplasm, and ultimately across the nuclear envelope and into the nucleus before any transcription can initiate. Immediately upon entry into the cytoplasm, naked DNA, either delivered through physical techniques or after disassembly of DNA-carrier complexes, associates with a large number of cellular proteins that mediate subsequent interactions with the microtubule network for movement toward the microtubule organizing center and the nuclear envelope. Plasmids then enter the nucleus either upon the mitotic disassembly of the nuclear envelope or through nuclear pore complexes in the absence of cell division, using a different set of proteins. This review will discuss our current understanding of these pathways used by naked DNA during the transfection process. While much has been elucidated on these processes, much remains to be discerned, but with the development of a number of model systems and approaches, great progress is being made.
Collapse
|
15
|
Šimčíková M, Prather KLJ, Prazeres DMF, Monteiro GA. Towards effective non-viral gene delivery vector. Biotechnol Genet Eng Rev 2017; 31:82-107. [PMID: 27160661 DOI: 10.1080/02648725.2016.1178011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Despite very good safety records, clinical trials using plasmid DNA failed due to low transfection efficiency and brief transgene expression. Although this failure is both due to poor plasmid design and to inefficient delivery methods, here we will focus on the former. The DNA elements like CpG motifs, selection markers, origins of replication, cryptic eukaryotic signals or nuclease-susceptible regions and inverted repeats showed detrimental effects on plasmids' performance as biopharmaceuticals. On the other hand, careful selection of promoter, polyadenylation signal, codon optimization and/or insertion of introns or nuclear-targeting sequences for therapeutic protein expression can enhance the clinical efficacy. Minimal vectors, which are devoid of the bacterial backbone and consist exclusively of the eukaryotic expression cassette, demonstrate better performance in terms of expression levels, bioavailability, transfection rates and increased therapeutic effects. Although the results are promising, minimal vectors have not taken over the conventional plasmids in clinical trials due to challenging manufacturing issues.
Collapse
Affiliation(s)
- Michaela Šimčíková
- a MIT-Portugal Program.,b iBB-Institute for Bioengineering and Biosciences , Lisbon , Portugal
| | - Kristala L J Prather
- a MIT-Portugal Program.,c Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , MA , USA
| | - Duarte M F Prazeres
- a MIT-Portugal Program.,c Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , MA , USA.,d Department of Bioengineering , Instituto Superior Técnico , Lisbon , Portugal
| | - Gabriel A Monteiro
- a MIT-Portugal Program.,c Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , MA , USA.,d Department of Bioengineering , Instituto Superior Técnico , Lisbon , Portugal
| |
Collapse
|
16
|
Oka T, Kurozumi K, Shimazu Y, Ichikawa T, Ishida J, Otani Y, Shimizu T, Tomita Y, Sakaguchi M, Watanabe M, Nasu Y, Kumon H, Date I. A super gene expression system enhances the anti-glioma effects of adenovirus-mediated REIC/Dkk-3 gene therapy. Sci Rep 2016; 6:33319. [PMID: 27625116 PMCID: PMC5022040 DOI: 10.1038/srep33319] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/24/2016] [Indexed: 12/26/2022] Open
Abstract
Reduced expression in immortalized cells/Dickkopf-3 (REIC/Dkk-3) is a tumor suppressor and therapeutic gene in many human cancers. Recently, an adenovirus REIC vector with the super gene expression system (Ad-SGE-REIC) was developed to increase REIC/Dkk-3 expression and enhance therapeutic effects compared with the conventional adenoviral vector (Ad-CAG-REIC). In this study, we investigated the in vitro and in vivo effects of Ad-SGE-REIC on malignant glioma. In U87ΔEGFR and GL261 glioma cells, western blotting confirmed that robust upregulation of REIC/Dkk-3 expression occurred in Ad-SGE-REIC-transduced cells, most notably after transduction at a multiplicity of infection of 10. Cytotoxicity assays showed that Ad-SGE-REIC resulted in a time-dependent and significant reduction in the number of malignant glioma cells attaching to the bottom of culture wells. Xenograft and syngeneic mouse intracranial glioma models treated with Ad-SGE-REIC had significantly longer survival than those treated with the control vector Ad-LacZ or with Ad-CAG-REIC. This study demonstrated the anti-glioma effect of Ad-SGE-REIC, which may represent a promising strategy for the treatment of malignant glioma.
Collapse
Affiliation(s)
- Tetsuo Oka
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Kazuhiko Kurozumi
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yosuke Shimazu
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Tomotsugu Ichikawa
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Joji Ishida
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yoshihiro Otani
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Toshihiko Shimizu
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Yusuke Tomita
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Masakiyo Sakaguchi
- Department of Cell Biology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Masami Watanabe
- Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan
| | - Yasutomo Nasu
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Hiromi Kumon
- Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Isao Date
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| |
Collapse
|
17
|
Chrenek MA, Nickerson JM, Boatright JH. Clustered Regularly Interspaced Short Palindromic Repeats: Challenges in Treating Retinal Disease. Asia Pac J Ophthalmol (Phila) 2016; 5:304-8. [PMID: 27488072 PMCID: PMC4975549 DOI: 10.1097/apo.0000000000000225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Ophthalmic researchers and clinicians arguably have led the way for safe, effective gene therapy, most notably with adeno-associated viral gene supplementation in the treatment for patients with Leber congenital amaurosis type 2 with mutations in the RPE65 gene. These successes notwithstanding, most other genetic retinal disease will be refractory to supplementation. The ideal gene therapy approach would correct gene mutations to restore normal function in the affected cells. Gene editing in which a mutant allele is inactivated or converted to sequence that restores normal function is hypothetically one such approach. Such editing involves site-specific digestion of mutant genomic DNA followed by repair. Previous experimental approaches were hampered by inaccurate and high rates of off-site lesioning and by overall low digestion rates. A new tool, clustered regularly interspaced short palindromic repeats coupled with the nuclease Cas9, may address both shortcomings. Some of the many challenges that must be addressed in moving clustered regularly interspaced short palindromic repeats coupled with the nuclease Cas9 therapies to the ophthalmic clinic are discussed here.
Collapse
Affiliation(s)
- Micah A. Chrenek
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia
| | - John M. Nickerson
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia
| | - Jeffrey H. Boatright
- Department of Ophthalmology, Emory University School of Medicine, Atlanta, Georgia
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Decatur, Georgia
| |
Collapse
|
18
|
Liu X, Liu Q, Xiao K, Li P, Liu Q, Zhao X, Kong Q. Attenuated Salmonella Typhimurium delivery of a novel DNA vaccine induces immune responses and provides protection against duck enteritis virus. Vet Microbiol 2016; 186:189-98. [PMID: 27016773 DOI: 10.1016/j.vetmic.2016.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/01/2016] [Accepted: 03/03/2016] [Indexed: 02/02/2023]
Abstract
DNA vaccines are widely used to prevent and treat infectious diseases, cancer and autoimmune diseases; however, their relatively low immunogenicity is an obstacle to their use. In this study, we constructed a novel and universal DNA vaccine vector (pSS898) that can be used to build DNA vaccines against duck enteritis virus (DEV) and other viruses that require DNA vaccines to provide protection. This vaccine vector has many advantages, including innate immunogenicity, efficient nuclear trafficking and resistance to attack from nucleases. UL24 and tgB from DEV were chosen as the antigens, and the heat labile enterotoxin B subunit (LTB) from Escherichia coli and the IL-2 gene (DuIL-2) from duck were used as adjuvants for the construction of DNA vaccine plasmids. Ducklings that were orally immunized with S739 (Salmonella Typhimurium Δasd-66 Δcrp-24 Δcya-25) and harboring these DEV DNA vaccines produced strong mucosal and systemic immune responses, and they resisted an otherwise lethal DEV challenge. More importantly, S739 (UL24-LTB) provided 90% protection after a priming-boost immunization. This study shows that our novel and universal DNA vaccine vector can be used efficiently in practical applications and may provide a promising method of orally inoculating ducks with a DEV DNA vaccine delivered by attenuated Salmonella Typhimurium for prevention of DVE.
Collapse
Affiliation(s)
- Xueyan Liu
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Qing Liu
- Department of Bioengineering, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
| | - Kangpeng Xiao
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Pei Li
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Qiong Liu
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - Qingke Kong
- Institute of Preventive Veterinary Medicine, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan 611130, China.
| |
Collapse
|
19
|
Rosazza C, Meglic SH, Zumbusch A, Rols MP, Miklavcic D. Gene Electrotransfer: A Mechanistic Perspective. Curr Gene Ther 2016; 16:98-129. [PMID: 27029943 PMCID: PMC5412002 DOI: 10.2174/1566523216666160331130040] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 11/22/2022]
Abstract
Gene electrotransfer is a powerful method of DNA delivery offering several medical applications, among the most promising of which are DNA vaccination and gene therapy for cancer treatment. Electroporation entails the application of electric fields to cells which then experience a local and transient change of membrane permeability. Although gene electrotransfer has been extensively studied in in vitro and in vivo environments, the mechanisms by which DNA enters and navigates through cells are not fully understood. Here we present a comprehensive review of the body of knowledge concerning gene electrotransfer that has been accumulated over the last three decades. For that purpose, after briefly reviewing the medical applications that gene electrotransfer can provide, we outline membrane electropermeabilization, a key process for the delivery of DNA and smaller molecules. Since gene electrotransfer is a multipart process, we proceed our review in describing step by step our current understanding, with particular emphasis on DNA internalization and intracellular trafficking. Finally, we turn our attention to in vivo testing and methodology for gene electrotransfer.
Collapse
Affiliation(s)
| | | | | | - Marie-Pierre Rols
- Institute of Pharmacology and Structural Biology (IPBS), CNRS UMR5089, 205 route de Narbonne, 31077 Toulouse, France.
| | | |
Collapse
|
20
|
Zulliger R, Conley SM, Naash MI. Non-viral therapeutic approaches to ocular diseases: An overview and future directions. J Control Release 2015; 219:471-487. [PMID: 26439665 PMCID: PMC4699668 DOI: 10.1016/j.jconrel.2015.10.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 10/01/2015] [Accepted: 10/02/2015] [Indexed: 12/31/2022]
Abstract
Currently there are no viable treatment options for patients with debilitating inherited retinal degeneration. The vast variability in disease-inducing mutations and resulting phenotypes has hampered the development of therapeutic interventions. Gene therapy is a logical approach, and recent work has focused on ways to optimize vector design and packaging to promote optimized expression and phenotypic rescue after intraocular delivery. In this review, we discuss ongoing ocular clinical trials, which currently use viral gene delivery, but focus primarily on new advancements in optimizing the efficacy of non-viral gene delivery for ocular diseases. Non-viral delivery systems are highly customizable, allowing functionalization to improve cellular and nuclear uptake, bypassing cellular degradative machinery, and improving gene expression in the nucleus. Non-viral vectors often yield transgene expression levels lower than viral counterparts, however their favorable safety/immune profiles and large DNA capacity (critical for the delivery of large ocular disease genes) make their further development a research priority. Recent work on particle coating and vector engineering presents exciting ways to overcome limitations of transient/low gene expression levels, but also highlights the fact that further refinements are needed before use in the clinic.
Collapse
Affiliation(s)
- Rahel Zulliger
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, United States
| | - Shannon M Conley
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204-5060, United States.
| |
Collapse
|
21
|
Crowley ST, Rice KG. "Evolving nanoparticle gene delivery vectors for the liver: What has been learned in 30 years". J Control Release 2015; 219:457-470. [PMID: 26439664 DOI: 10.1016/j.jconrel.2015.10.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Revised: 10/01/2015] [Accepted: 10/02/2015] [Indexed: 12/18/2022]
Abstract
Nonviral gene delivery to the liver has been under evolution for nearly 30years. Early demonstrations established relatively simple nonviral vectors could mediate gene expression in HepG2 cells which understandably led to speculation that these same vectors would be immediately successful at transfecting primary hepatocytes in vivo. However, it was soon recognized that the properties of a nonviral vector resulting in efficient transfection in vitro were uncorrelated with those needed to achieve efficient nonviral transfection in vivo. The discovery of major barriers to liver gene transfer has set the field on a course to design biocompatible vectors that demonstrate increased DNA stability in the circulation with correlating expression in liver. The improved understanding of what limits nonviral vector gene transfer efficiency in vivo has resulted in more sophisticated, low molecular weight vectors that allow systematic optimization of nanoparticle size, charge and ligand presentation. While the field has evolved DNA nanoparticles that are stable in the circulation, target hepatocytes, and deliver DNA to the cytosol, breaching the nucleus remains the last major barrier to a fully successful nonviral gene transfer system for the liver. The lessons learned along the way are fundamentally important to the design of all systemically delivered nanoparticle nonviral gene delivery systems.
Collapse
Affiliation(s)
- Samuel T Crowley
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, IA 52242,USA
| | - Kevin G Rice
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, IA 52242,USA.
| |
Collapse
|
22
|
Abstract
Electroporation has been used extensively to transfer DNA to bacteria, yeast, and mammalian cells in culture for the past 30 years. Over this time, numerous advances have been made, from using fields to facilitate cell fusion, delivery of chemotherapeutic drugs to cells and tissues, and most importantly, gene and drug delivery in living tissues from rodents to man. Electroporation uses electrical fields to transiently destabilize the membrane allowing the entry of normally impermeable macromolecules into the cytoplasm. Surprisingly, at the appropriate field strengths, the application of these fields to tissues results in little, if any, damage or trauma. Indeed, electroporation has even been used successfully in human trials for gene delivery for the treatment of tumors and for vaccine development. Electroporation can lead to between 100 and 1000-fold increases in gene delivery and expression and can also increase both the distribution of cells taking up and expressing the DNA as well as the absolute amount of gene product per cell (likely due to increased delivery of plasmids into each cell). Effective electroporation depends on electric field parameters, electrode design, the tissues and cells being targeted, and the plasmids that are being transferred themselves. Most importantly, there is no single combination of these variables that leads to greatest efficacy in every situation; optimization is required in every new setting. Electroporation-mediated in vivo gene delivery has proven highly effective in vaccine production, transgene expression, enzyme replacement, and control of a variety of cancers. Almost any tissue can be targeted with electroporation, including muscle, skin, heart, liver, lung, and vasculature. This chapter will provide an overview of the theory of electroporation for the delivery of DNA both in individual cells and in tissues and its application for in vivo gene delivery in a number of animal models.
Collapse
Affiliation(s)
- Jennifer L Young
- Department of Pediatrics, University of Rochester, Rochester, NY, USA
| | - David A Dean
- Departments of Pediatrics and Biomedical Engineering, University of Rochester, Rochester, NY, USA
| |
Collapse
|
23
|
Pasquet L, Bellard E, Golzio M, Rols MP, Teissie J. A double-pulse approach for electrotransfection. J Membr Biol 2014; 247:1253-8. [PMID: 25135167 DOI: 10.1007/s00232-014-9720-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 08/07/2014] [Indexed: 11/26/2022]
Abstract
Gene transfer and expression can be obtained by delivering calibrated electric pulses on cells in the presence of plasmids coding for the activity of interest. The electric treatment affects the plasma membrane and induces the formation of a transient complex between nucleic acids and the plasma membrane. It results in a delivery of the plasmid in the cytoplasm. Expression is only obtained if the plasmid is translocated inside the nucleus. This is a key limit in the process. We previously showed that delivery of a high-field short-duration electric pulse was inducing a structural alteration of the nuclear envelope. This study investigates if the double-pulse approach (first pulse to transfer the plasmid to the cytoplasm, and second pulse to induce the structural alteration of the envelope) was a way to enhance the protein expression using the green fluorescent protein as a reporter. We observed that not only the double-pulse approach induced the transfection of a lower number of cells but moreover, these transfected cells were less fluorescent than the cells treated only with the first pulse.
Collapse
Affiliation(s)
- L Pasquet
- Centre National de la Recherche Scientifique, Institut de Pharmacologie et de Biologie Structurale, BP64182, 205 route de Narbonne, 31077, Toulouse, France
| | | | | | | | | |
Collapse
|
24
|
Pereira VB, Zurita-Turk M, Saraiva TDL, De Castro CP, Souza BM, Mancha Agresti P, Lima FA, Pfeiffer VN, Azevedo MSP, Rocha CS, Pontes DS, Azevedo V, Miyoshi A. DNA Vaccines Approach: From Concepts to Applications. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/wjv.2014.42008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
25
|
Watanabe M, Sakaguchi M, Kinoshita R, Kaku H, Ariyoshi Y, Ueki H, Tanimoto R, Ebara S, Ochiai K, Futami J, Li SA, Huang P, Nasu Y, Huh NH, Kumon H. A novel gene expression system strongly enhances the anticancer effects of a REIC/Dkk-3-encoding adenoviral vector. Oncol Rep 2013; 31:1089-95. [PMID: 24398705 PMCID: PMC3926669 DOI: 10.3892/or.2013.2958] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 09/30/2013] [Indexed: 11/25/2022] Open
Abstract
Gene expression systems with various promoters, including the cytomegalovirus (CMV) promoter, have been developed to increase the gene expression in a variety of normal and cancer cells. In particular, in the clinical trials of cancer gene therapy, a more efficient and robust gene expression system is required to achieve sufficient therapeutic outcomes. By inserting the triple translational enhancer sequences of human telomerase reverse transcriptase (hTERT), Simian virus 40 (SV40) and CMV downstream of the sequence of the BGH polyA, we were able to develop a novel gene expression system that significantly enhances the expression of the genes of interest. We termed this novel gene expression cassette the super gene expression (SGE) system, and herein verify the utility of the SGE cassette for a replication-deficient adenoviral vector. We newly developed an adenoviral vector expressing the tumor suppressor, reduced expression in immortalized cells (REIC)/Dickkopf-3 (Dkk-3), based on the CMV promoter-driven SGE system (Ad-SGE-REIC) and compared the therapeutic utility of Ad-SGE-REIC with that of the conventional adenoviral vectors (Ad-CMV-REIC or Ad-CAG-REIC). The results demonstrated that the CMV promoter-SGE system allows for more potent gene expression, and that the Ad-SGE-REIC is superior to conventional adenoviral systems in terms of the REIC protein expression and therapeutic effects. Since the SGE cassette can be applied for the expression of various therapeutic genes using various vector systems, we believe that this novel system will become an innovative tool in the field of gene expression and gene therapy.
Collapse
Affiliation(s)
- Masami Watanabe
- Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan
| | | | - Rie Kinoshita
- Department of Medical and Bioengineering Science, Okayama University, Okayama, Japan
| | - Haruki Kaku
- Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan
| | | | - Hideo Ueki
- Department of Urology, Okayama University, Okayama, Japan
| | - Ryuta Tanimoto
- Department of Urology, Okayama University, Okayama, Japan
| | - Shin Ebara
- Department of Urology, Okayama University, Okayama, Japan
| | - Kazuhiko Ochiai
- Department of Veterinary Nursing and Technology, Nippon Veterinary and Life Science University, Musashino, Tokyo, Japan
| | - Junichiro Futami
- Department of Medical and Bioengineering Science, Okayama University, Okayama, Japan
| | - Shun-Ai Li
- Department of Urology, Okayama University, Okayama, Japan
| | - Peng Huang
- Department of Urology, Okayama University, Okayama, Japan
| | - Yasutomo Nasu
- Center for Innovative Clinical Medicine, Okayama University Hospital, Okayama, Japan
| | - Nam-Ho Huh
- Department of Cell Biology, Okayama University, Okayama, Japan
| | - Hiromi Kumon
- Department of Urology, Okayama University, Okayama, Japan
| |
Collapse
|
26
|
Cell-specific targeting strategies for electroporation-mediated gene delivery in cells and animals. J Membr Biol 2013; 246:737-44. [PMID: 23525583 DOI: 10.1007/s00232-013-9534-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/08/2013] [Indexed: 01/19/2023]
Abstract
The use of electroporation to facilitate gene transfer is an extremely powerful and useful method for both in vitro and in vivo applications. One of its great strengths is that it induces functional destabilization and permeabilization of cell membranes throughout a tissue leading to widespread gene transfer to multiple cells and cell types within the electric field. While this is a strength, it can also be a limitation in terms of cell-specific gene delivery. The ability to restrict gene delivery and expression to particular cell types is of paramount importance for many types of gene therapy, since ectopic expression of a transgene could lead to deleterious host inflammatory responses or dysregulation of normal cellular functions. At present, there are relatively few ways to obtain cell-specific targeting of nonviral vectors, molecular probes, small molecules, and imaging agents. We have developed a novel means of restricting gene delivery to desired cell types based on the ability to control the transport of plasmids into the nuclei of desired cell types. In this article, we discuss the mechanisms of this approach and several applications in living animals to demonstrate the benefits of the combination of electroporation and selective nuclear import of plasmids for cell-specific gene delivery.
Collapse
|
27
|
Kong W, Brovold M, Koeneman BA, Clark-Curtiss J, Curtiss R. Turning self-destructing Salmonella into a universal DNA vaccine delivery platform. Proc Natl Acad Sci U S A 2012; 109:19414-9. [PMID: 23129620 PMCID: PMC3511069 DOI: 10.1073/pnas.1217554109] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We previously developed a biological containment system using recombinant Salmonella Typhimurium strains that are attenuated yet capable of synthesizing protective antigens. The regulated delayed attenuation and programmed self-destructing features designed into these S. Typhimurium strains enable them to efficiently colonize host tissues and allow release of the bacterial cell contents after lysis. To turn such a recombinant attenuated Salmonella vaccine (RASV) strain into a universal DNA vaccine-delivery vehicle, our approach was to genetically modify RASV strains to display a hyperinvasive phenotype to maximize Salmonella host entry and host cell internalization, to enable Salmonella endosomal escape to release a DNA vaccine into the cytosol, and to decrease Salmonella-induced pyroptosis/apoptosis that allows the DNA vaccine time to traffic to the nucleus for efficient synthesis of encoded protective antigens. A DNA vaccine vector that encodes a domain that contributes to the arabinose-regulated lysis phenotype but has a eukaryotic promoter was constructed. The vector was then improved by insertion of multiple DNA nuclear-targeting sequences for efficient nuclear trafficking and gene expression, and by increasing nuclease resistance to protect the plasmid from host degradation. A DNA vaccine encoding influenza WSN virus HA antigen delivered by the RASV strain with the best genetic attributes induced complete protection to mice against a lethal influenza virus challenge. Adoption of these technological improvements will revolutionize means for effective delivery of DNA vaccines to stimulate mucosal, systemic, and cellular protective immunities, and lead to a paradigm shift in cost-effective control and prevention of a diversity of diseases.
Collapse
MESH Headings
- Active Transport, Cell Nucleus
- Animals
- Antibodies, Bacterial/immunology
- Antibody Formation/immunology
- Apoptosis
- Base Sequence
- Deoxyribonucleases/metabolism
- Gene Transfer Techniques
- Genes, Bacterial/genetics
- Genetic Engineering
- Genetic Vectors/genetics
- Hemagglutinin Glycoproteins, Influenza Virus/immunology
- Immunization
- Mice
- Molecular Sequence Data
- Plasmids/genetics
- Salmonella/genetics
- Salmonella/immunology
- Salmonella Infections, Animal/immunology
- Salmonella Infections, Animal/microbiology
- Salmonella Infections, Animal/prevention & control
- Salmonella Vaccines/immunology
- Vaccines, Attenuated/immunology
- Vaccines, DNA/immunology
- Vaccines, Synthetic/immunology
Collapse
Affiliation(s)
- Wei Kong
- Center for Infectious Diseases and Vaccinology at the Biodesign Institute, and
| | - Matthew Brovold
- Center for Infectious Diseases and Vaccinology at the Biodesign Institute, and
| | | | - Josephine Clark-Curtiss
- Center for Infectious Diseases and Vaccinology at the Biodesign Institute, and
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-5401; and
| | - Roy Curtiss
- Center for Infectious Diseases and Vaccinology at the Biodesign Institute, and
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-5401; and
| |
Collapse
|
28
|
Badding MA, Lapek JD, Friedman AE, Dean DA. Proteomic and functional analyses of protein-DNA complexes during gene transfer. Mol Ther 2012; 21:775-85. [PMID: 23164933 DOI: 10.1038/mt.2012.231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
One of the barriers to successful nonviral gene delivery is the crowded cytoplasm, which plasmids need to actively traverse for gene expression. Relatively little is known about how this process occurs, but our lab and others have shown that the microtubule network and motors are required for plasmid movement to the nucleus. To further investigate how plasmids exploit normal physiological processes to transfect cells, we have taken a proteomics approach to identify the proteins that comprise the plasmid-trafficking complex. We have developed a live cell DNA-protein pull-down assay to isolate complexes at certain time points post-transfection (15 minutes to 4 hours) for analysis by mass spectrometry (MS). Plasmids containing promoter sequences bound hundreds of unique proteins as early as 15 minutes post-electroporation, while a plasmid lacking any eukaryotic sequences failed to bind many of the proteins. Specific proteins included microtubule-based motor proteins (e.g., kinesin and dynein), proteins involved in protein nuclear import (e.g., importin 1, 2, 4, and 7, Crm1, RAN, and several RAN-binding proteins), a number of heterogeneous nuclear ribonucleoprotein (hnRNP)- and mRNA-binding proteins, and transcription factors. The significance of several of the proteins involved in protein nuclear localization and plasmid trafficking was determined by monitoring movement of microinjected fluorescently labeled plasmids via live cell particle tracking in cells following protein knockdown by small-interfering RNA (siRNA) or through the use of specific inhibitors. While importin β1 was required for plasmid trafficking and subsequent nuclear import, importin α1 played no role in microtubule trafficking but was required for optimal plasmid nuclear import. Surprisingly, the nuclear export protein Crm1 also was found to complex with the transfected plasmids and was necessary for plasmid trafficking along microtubules and nuclear import. Our results show that various proteins involved in nuclear import and export influence intracellular trafficking of plasmids and subsequent nuclear accumulation.
Collapse
Affiliation(s)
- Melissa A Badding
- Department of Pediatrics, Division of Neonatology, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
| | | | | | | |
Collapse
|
29
|
Hyperactive self-inactivating piggyBac for transposase-enhanced pronuclear microinjection transgenesis. Proc Natl Acad Sci U S A 2012; 109:19184-9. [PMID: 23093669 DOI: 10.1073/pnas.1216473109] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have developed a unique method for mouse transgenesis. The transposase-enhanced pronuclear microinjection (PNI) technique described herein uses the hyperactive piggyBac transposase to insert a large transgene into the mouse genome. This procedure increased transgene integration efficiency by fivefold compared with conventional PNI or intracytoplasmic sperm injection-mediated transgenesis. Our data indicate that the transposase-enhanced PNI technique additionally requires fewer embryos to be microinjected than traditional methods to obtain transgenic animals. This transposase-mediated approach is also very efficient for single-cell embryo cytoplasmic injections, offering an easy-to-implement transgenesis method to the scientific community.
Collapse
|
30
|
Satkauskas S, Ruzgys P, Venslauskas MS. Towards the mechanisms for efficient gene transfer into cells and tissues by means of cell electroporation. Expert Opin Biol Ther 2012; 12:275-86. [PMID: 22339479 DOI: 10.1517/14712598.2012.654775] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Intracellular gene electrotransfer by means of electroporation has been on the increase during the past decade. Significant progress has been achieved both in characterizing mechanisms of gene electrotransfer and in optimizing the protocol in many preclinical trials. Recently this has led to initiation of clinical trials of gene electrotransfer to treat metastatic melanomas. Further progress with the method in various clinical trials requires better understanding of mechanisms of gene electrotransfer. AREAS COVERED A summary of recent progress in understanding mechanisms of gene electrotransfer, imparting general knowledge of cell electroporation and intracellular molecule electrotransfer. EXPERT OPINION Gene electrotransfer into cells and tissues is a complex process involving multiple steps that lead to plasmid DNA passage from the extracellular region to the cell nucleus crossing the barriers of the plasma membrane, cytoplasm and nucleus membrane. Electrical parameters of pulses used for gene electrotransfer affect the initial steps of DNA translocation through the plasma membrane and play a crucial role in determining the transfection efficiency. When considering gene electrotransfer into tissues it becomes clear that other nonelectrical conditions are also of primary importance.
Collapse
Affiliation(s)
- Saulius Satkauskas
- Vytautas Magnus University, Biology Department, Biophysical Research Group, Vileikos 8, Kaunas LT-44404, Lithuania.
| | | | | |
Collapse
|
31
|
Sjeklocha L, Chen Y, Daly MC, Steer CJ, Kren BT. β-globin matrix attachment region improves stable genomic expression of the Sleeping Beauty transposon. J Cell Biochem 2011; 112:2361-2375. [PMID: 21520245 DOI: 10.1002/jcb.23159] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The liver is an attractive target for gene therapy due to its extensive capability for protein production and the numerous diseases resulting from a loss of gene function it normally provides. The Sleeping Beauty Transposon (SB-Tn)(1) system is a non-viral vector capable of delivering and mediating therapeutic transgene(s) insertion into the host genome for long-term expression. A current challenge for this system is the low efficiency of integration of the transgene. In this study we use a human hepatoma cell line (HuH-7) and primary human blood outgrowth endothelial cells (BOECs) to test vectors containing DNA elements to enhance transposition without integrating themselves. We employed the human β-globin matrix attachment region (MAR) and the Simian virus 40 (SV40) nuclear translocation signal to increase the percent of HuH-7 cells persistently expressing a GFP::Zeo reporter construct by ∼50% for each element; while combining both did not show an additive effect. Interestingly, both elements together displayed an additive effect on the number of insertion sites, and in BOECs the SV40 alone appeared to have an inhibitory effect on transposition. In long-term cultures the loss of plasmid DNA, transposase expression and mapping of insertion sites demonstrated bona fide transposition without episomal expression. These results show that addition of the β-globin MAR and potentially other elements to the backbone of SB-Tn system can enhance transposition and expression of therapeutic transgenes. These findings may have a significant influence on the use of SB transgene delivery to liver for the treatment of a wide variety of disorders.
Collapse
Affiliation(s)
- Lucas Sjeklocha
- Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, 55455
| | - Yixin Chen
- Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, 55455
| | - Meghan C Daly
- Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, 55455
| | - Clifford J Steer
- Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, 55455.,Department of Genetics, Cell Biology and Development, University of Minnesota Medical School, Minneapolis, Minnesota, 55455
| | - Betsy T Kren
- Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, 55455
| |
Collapse
|
32
|
Abstract
Gene transfer within the cardiovascular system was first demonstrated in 1989 yet, despite extensive basic-science and clinical research, unequivocal benefit in the clinical setting remains to be demonstrated. Potential reasons for this include the fact that recombinant viral vectors, used in the majority of clinical studies, have inherent problems with immunogenicity that are difficult to circumvent. Attention has turned therefore to plasmid vectors, which possess many advantages over viruses in terms of safety and ease of use, and many clinical studies have now been performed using non-viral technology. This review will provide an overview of clinical trials for cardiovascular disease using plasmid vectors, recent developments in plasmid delivery and design, and potential directions for this modality of gene therapy.
Collapse
Affiliation(s)
- Paul D Williams
- Manchester Academic Health Science Centre, School of Biomedicine, Vascular Gene Therapy Unit, Core Technology Facility, The University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK.
| | | |
Collapse
|
33
|
How to screen non-viral gene delivery systems in vitro? J Control Release 2011; 154:218-32. [PMID: 21600249 DOI: 10.1016/j.jconrel.2011.05.001] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Revised: 03/31/2011] [Accepted: 05/01/2011] [Indexed: 11/21/2022]
Abstract
Screening of new gene delivery candidates regarding transfection efficiency and toxicity is usually performed by reading out transgene expression levels relative to a reference formulation after in vitro transfection. However, over the years and among different laboratories, this screening has been performed in a variety of cell lines, using a variety of conditions and read-out systems, and by comparison to a variety of reference formulations. This makes a direct comparison of results difficult, if not impossible. Reaching a consensus would enable placing new results into context of previous findings and estimate the overall contribution to the improvement of non-viral gene delivery. In this paper we illustrate the sensitivity of transfection outcomes on testing conditions chosen, and propose a screening protocol with the aim of standardization within the field.
Collapse
|
34
|
van Gaal EVB, Oosting RS, van Eijk R, Bakowska M, Feyen D, Kok RJ, Hennink WE, Crommelin DJA, Mastrobattista E. DNA nuclear targeting sequences for non-viral gene delivery. Pharm Res 2011; 28:1707-22. [PMID: 21424159 PMCID: PMC3109246 DOI: 10.1007/s11095-011-0407-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 02/21/2011] [Indexed: 12/02/2022]
Abstract
Purpose To evaluate if introduction of DNA nuclear Targeting Sequences (DTS; i.e. recognition sequences for endogenous DNA-binding proteins) in plasmid DNA (pDNA) leads to increased transfection efficiency of non-viral gene delivery by virtue of enhanced nuclear import of the pDNA. Methods A set of DTS was identified and cloned into EGFP-reporter plasmids controlled by the CMV-promoter. These pDNA constructs were delivered into A431 and HeLa cells using standard electroporation, pEI-based polyfection or lipofection methods. The amount of pDNA delivered into the nucleus was determined by qPCR; transfection efficiency was determined by flow cytometry. Results Neither of these DTS increased transgene expression. We varied several parameters (mitotic activity, applied dose and delivery strategy), but without effect. Although upregulated transgene expression was observed after stimulation with TNF-α, this effect could be ascribed to non-specific upregulation of transcription rather than enhanced nuclear import. Nuclear copy numbers of plasmids containing or lacking a DTS did not differ significantly after lipofectamine-based transfection in dividing and non-dividing cells. Conclusion No beneficial effects of DTS on gene expression or nuclear uptake were observed in this study.
Collapse
Affiliation(s)
- Ethlinn V B van Gaal
- Department of Pharmaceutics, Utrecht Institute of Pharmaceutical Sciences, Utrecht University, 3584 CA, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Sacramento CB, Moraes JZ, Denapolis PMA, Han SW. Gene expression promoted by the SV40 DNA targeting sequence and the hypoxia-responsive element under normoxia and hypoxia. Braz J Med Biol Res 2010; 43:722-7. [PMID: 20640386 DOI: 10.1590/s0100-879x2010007500064] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Accepted: 06/30/2010] [Indexed: 11/21/2022] Open
Abstract
The main objective of the present study was to find suitable DNA-targeting sequences (DTS) for the construction of plasmid vectors to be used to treat ischemic diseases. The well-known Simian virus 40 nuclear DTS (SV40-DTS) and hypoxia-responsive element (HRE) sequences were used to construct plasmid vectors to express the human vascular endothelial growth factor gene (hVEGF). The rate of plasmid nuclear transport and consequent gene expression under normoxia (20% O2) and hypoxia (less than 5% O2) were determined. Plasmids containing the SV40-DTS or HRE sequences were constructed and used to transfect the A293T cell line (a human embryonic kidney cell line) in vitro and mouse skeletal muscle cells in vivo. Plasmid transport to the nucleus was monitored by real-time PCR, and the expression level of the hVEGF gene was measured by ELISA. The in vitro nuclear transport efficiency of the SV40-DTS plasmid was about 50% lower under hypoxia, while the HRE plasmid was about 50% higher under hypoxia. Quantitation of reporter gene expression in vitro and in vivo, under hypoxia and normoxia, confirmed that the SV40-DTS plasmid functioned better under normoxia, while the HRE plasmid was superior under hypoxia. These results indicate that the efficiency of gene expression by plasmids containing DNA binding sequences is affected by the concentration of oxygen in the medium.
Collapse
Affiliation(s)
- C B Sacramento
- Centro Interdisciplinar de Terapia Gênica, Universidade Federal de São Paulo
| | | | | | | |
Collapse
|
36
|
The SP-C promoter facilitates alveolar type II epithelial cell-specific plasmid nuclear import and gene expression. Gene Ther 2010; 17:541-9. [PMID: 20054353 PMCID: PMC3482943 DOI: 10.1038/gt.2009.166] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Although nonviral gene therapy has great potential for use in the lung, the relative lack of cell-specific targeting has limited its applications. We have developed a new approach for cell-specific targeting based on selective nuclear import of plasmids in non-dividing cells. Using a microinjection and in situ hybridization approach, we tested several potential DNA sequences for the ability to mediate plasmid nuclear import in alveolar type II epithelial (ATII) cells. Of these, only a sequence within the human surfactant protein C (SP-C) promoter was able to mediate nuclear localization of plasmid DNA specifically in ATII cells but not in other cell types. We have mapped the minimal import sequence to the proximal 318 nucleotides of the promoter, and demonstrate that binding sites for NFI, TTF-1, and GATA-6 and the proteins themselves are required for import activity. Using intratracheal delivery of DNA followed by electroporation, we demonstrate that the SP-C promoter sequence will enhance gene expression specifically in ATII cells in mouse lung. This represents a novel activity for the SP-C promoter and thus ATII cell-specific nuclear import of DNA may prove to be a safe and effective method for targeted and enhanced gene expression in ATII cells.
Collapse
|
37
|
Abstract
Improving the transfection efficiencies of nonviral gene delivery requires properly engineered nanoscaled delivery carriers that can overcome the multiple barriers associated with the delivery of oligonucleotides from the site of administration to the nucleus or cytoplasm of the target cell. This article reviews the current advantages and limitation of polyplex nonviral delivery systems, including the apparent barriers that limit gene expression efficiency compared to physical methods such as hydrodynamic dosing and electroporation. An emphasis is placed on engineered nanoscaled polyplexes (NSPs) of modular design that both self-assemble and systematically disassemble at the desired stage of delivery. It is suggested that NSPs of increasingly sophisticated designs are necessary to improve the efficiency of the rate limiting steps in gene delivery.
Collapse
Affiliation(s)
- Christian A Fernandez
- Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, USA
| | | |
Collapse
|
38
|
Kren BT, Yin W, Key NS, Hebbel RP, Steer CJ. Blood Outgrowth Endothelial Cells as a Vehicle for Transgene Expression of Hepatocyte-Secreted Proteins viaSleeping Beauty. ACTA ACUST UNITED AC 2009; 14:97-104. [PMID: 17497366 DOI: 10.1080/10623320701346932] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The therapeutic use of autologous cells with the capacity for extensive in vitro expansion and manipulation prior to host administration has been an area of significant investigation over the last decade. Blood outgrowth endothelial cells (BOECs) are derived from the circulation and exhibit proliferative growth, in vivo engraftment, and survival characteristics for long-term expression of endogenously secreted proteins, such as factor VIII (FVIII). The authors describe a modified method for the isolation, culture, and expansion of these cells that is readily accomplished using standard laboratory methods. Using a commercially available transfection reagent, approximately 30% of these primary cells can be routinely transfected with the nonviral Sleeping Beauty transposon for long-term, stable transgene expression. Moreover, the results indicate that these cells have the ability to secrete functionally active proteins that are synthesized endogenously by hepatocytes and require post-translational modification including alpha1-antitrypsin and clotting factors VII and IX. This, coupled with their notably long half-life of years, suggests that these cells may provide an appropriate vehicle for secretion of a variety of proteins produced by different cell types in vivo. Thus, BOECs have the potential to provide clinically relevant secreted proteins for diseases other than those of endothelial origin.
Collapse
Affiliation(s)
- Betsy T Kren
- Department of Medicine, University of Minnesota Medical School, 420 Delaware Street SE, Minneapolis, MN 55455, USA.
| | | | | | | | | |
Collapse
|
39
|
Miller AM, Dean DA. Tissue-specific and transcription factor-mediated nuclear entry of DNA. Adv Drug Deliv Rev 2009; 61:603-13. [PMID: 19393704 DOI: 10.1016/j.addr.2009.02.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2008] [Accepted: 02/05/2009] [Indexed: 12/22/2022]
Abstract
Low levels of gene transfer and a lack of tissue-specific targeting of vectors have limited the therapeutic potential of non-viral gene therapy. This is due to the numerous cellular barriers that hinder nuclear delivery of vectors and the paucity of methods that restrict expression to specific cells types. In non-dividing cells, the nuclear envelope is an especially problematic hurdle to gene transfer. Given that the majority of target tissues are non-dividing in vivo, the nuclear membrane is a major obstacle to therapeutic gene transfer. In this review, the various barriers to gene transfer are discussed. In particular, the role of the nuclear pore complex (NPC) in regulating passage of plasmid vectors during interphase is reviewed. Several methods of modifying plasmid (pDNA) vectors to enhance nuclear import through the NPC are also discussed, including the use of tissue-specific transcription factors to mediate nuclear entry of pDNA in a cell-specific manner.
Collapse
Affiliation(s)
- Aaron M Miller
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | | |
Collapse
|
40
|
|
41
|
Identification of protein cofactors necessary for sequence-specific plasmid DNA nuclear import. Mol Ther 2009; 17:1897-903. [PMID: 19532138 DOI: 10.1038/mt.2009.127] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Although transfections are routinely used in the laboratory, the mechanism(s) by which exogenous DNA is transported into the nucleus is poorly understood. By improving our understanding of how vectors circumvent the numerous cellular barriers to gene transfer, more efficient gene delivery methods can be devised. We have begun to design plasmid constructs that enter the nucleus of specific cell types in the absence of cell division, thereby enhancing levels of expression. We have shown that inclusion of specific DNA sequences in plasmid constructs mediates nuclear import both in vitro and in vivo. Here, we use plasmid affinity chromatography, mass spectrometry (MS), and live-cell pulldowns of transfected plasmid constructs to identify protein cofactors that interact in a sequence-specific manner with these DNA nuclear targeting sequences (DTSs). Importin beta(1), importin 7, and the small guanosine triphosphatase Ran all demonstrate DTS-specific interaction in both MS and pull-down assays, consistent with our model of plasmid nuclear import. In addition, knockdown of importin beta(1) with small interfering RNA (siRNA) abrogates plasmid nuclear import, indicating that it is a necessary cofactor. Our discovery that specific karyopherins mediate plasmid nuclear import can be used to design more effective vectors for gene delivery.
Collapse
|
42
|
Lam AP, Dean DA. Cyclic stretch-induced nuclear localization of transcription factors results in increased nuclear targeting of plasmids in alveolar epithelial cells. J Gene Med 2008; 10:668-78. [PMID: 18361478 PMCID: PMC4084625 DOI: 10.1002/jgm.1187] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND We have shown previously that cyclic stretch corresponding to that experienced by the pulmonary epithelium during normal breathing enhances nonviral gene transfer and expression in alveolar epithelial cells by increasing plasmid intracellular trafficking. Although reorganization of the microtubule and actin cytoskeletons by cyclic stretch is necessary for increased plasmid trafficking, the role of nuclear entry in this enhanced trafficking has not been elucidated. METHODS Alveolar epithelial cells were subjected to biaxial cyclic stretch (10% change in surface area at 0.5 Hz) and assayed for RNA expression, nuclear localization and activation of key transcription factors. Stretched epithelial cells were transfected with plasmids via electroporation and exposed to inhibitors of transcription factor activation. RESULTS When assayed by in situ hybridization, more plasmids were localized to the nuclei of cells that were stretched following electroporation compared to unstretched cells. Cyclic stretch also increases the nuclear localization of multiple transcription factors thought to be involved in plasmid nuclear entry, including AP1, AP2, NF-kappaB and NF1. Specific inhibition of the nuclear import of AP1 and/or NF-kappaB abolishes the enhanced plasmid nuclear localization seen with stretch. CONCLUSIONS Nuclear entry of plasmids is thought to be mediated by the binding of proteins that chaperone the DNA through the nuclear pore. Stretch-enhanced nuclear localization of transcription factors increases nuclear targeting of plasmids, whereas inhibition of the nuclear import of specific transcription factors abrogated stretch-enhanced plasmid nuclear localization. Taken together, these results suggest that cyclic stretch increases gene trafficking in the cytoplasm and at the nuclear envelope.
Collapse
Affiliation(s)
- Anna P. Lam
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, North-western University, Chicago, IL, USA
| | - David A. Dean
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, North-western University, Chicago, IL, USA
- Department of Pediatrics, University or Rochester, Rochester, NY, USA
| |
Collapse
|
43
|
Miller AM, Dean DA. Cell-specific nuclear import of plasmid DNA in smooth muscle requires tissue-specific transcription factors and DNA sequences. Gene Ther 2008; 15:1107-15. [PMID: 18496575 DOI: 10.1038/gt.2008.83] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Two shortcomings of nonviral gene therapy are a lack of tissue-specific targeting of vectors and low levels of gene transfer. Our laboratory has begun to address these limitations by designing plasmids that enter the nucleus of specific cell types in the absence of cell division, thereby enhancing expression in a controlled manner. We have shown that a 176 bp portion of the smooth muscle gamma-actin (SMGA) promoter can mediate plasmid nuclear import specifically in smooth muscle cells (SMCs). Here, we demonstrate that the binding sites for serum response factor (SRF) and NKX3-1/3-2 within this DNA nuclear targeting sequence (DTS) are required for plasmid nuclear import. Knockdown of these factors with siRNA abrogates plasmid nuclear import, indicating that they are necessary cofactors. In addition, coinjection of recombinant SRF and Nkx3.2 with the vector in TC7 epithelial cells rescues import. Finally, we show that the SRF nuclear localization sequence (NLS) is required for vector nuclear import. We propose that SRF and NKX3-1/3-2 bind the SMGA DTS in the cytoplasm, thus coating the plasmid with NLSs that mediate translocation across the nuclear pore complex. This discovery could aid in the development of more efficient nonviral vectors for gene transfer to SMCs.
Collapse
Affiliation(s)
- A M Miller
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | |
Collapse
|
44
|
Young JL, Zimmer WE, Dean DA. Smooth muscle-specific gene delivery in the vasculature based on restriction of DNA nuclear import. Exp Biol Med (Maywood) 2008; 233:840-8. [PMID: 18445769 DOI: 10.3181/0712-rm-331] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The two currently employed approaches restricting gene delivery and/or expression to desired cell types in vivo rely on cell surface targeting or cell-specific promoters. We have developed a third approach based on cell-specific nuclear transport of the delivered plasmid DNA. We have previously shown that plasmid nuclear import in non-dividing cells is sequence-specific and have identified a set of cell-specific DNA nuclear targeting sequences that can be used to limit DNA nuclear import to desired cell types. Specifically we have identified elements of the smooth muscle gamma actin (SMGA) promoter that direct plasmid nuclear import selectively in smooth muscle cells (SMCs) in vitro (Vacik et al, 1999, Gene Therapy 6:1006-1014). In the present study, we demonstrate that the SMC-specific DNA nuclear targeting sequence from the SMGA promoter drives nuclear accumulation of plasmids and subsequent gene expression exclusively in the smooth muscle cell layer of the vessel wall in the intact vasculature of rats using electroporation mediated delivery. These results demonstrate that certain DNA nuclear targeting sequences can be used to restrict DNA nuclear import to specific cell types providing a new, novel means of cell targeting for gene therapy.
Collapse
Affiliation(s)
- Jennifer L Young
- Division of Neonatology, University of Rochester, Box 850, 601 Elmwood Ave, Rochester, NY 14642, USA
| | | | | |
Collapse
|
45
|
Dean D, Ramanathan T, Machado D, Sundararajan R. Electrical Impedance Spectroscopy Study of Biological Tissues. JOURNAL OF ELECTROSTATICS 2008; 66:165-177. [PMID: 19255614 PMCID: PMC2597841 DOI: 10.1016/j.elstat.2007.11.005] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The objective of this study was to investigate the electrical impedance properties of rat lung and other tissues ex vivo using Electrical Impedance Spectroscopy. Rat lungs (both electroporated and naïve (untreated)), and mesenteric vessels (naïve) were harvested from male Sprague-Dawley rats; their electrical impedance were measured using a Solartron 1290 impedance analyzer. Mouse lung and heart samples (naïve) were also studied. The resistance (Real Z, ohm) and the reactance (Im Z, negative ohm)) magnitudes and hence the Cole-Cole (Real Z versus Im Z) plots are different for the electroporated lung and the naive lung. The results confirm the close relationship between the structure and the functional characteristic. These also vary for the different biological tissues studied. The impedance values were higher at low frequencies compared to those at high frequencies. This study is of practical interest for biological applications of electrical pulses, such as electroporation, whose efficacy depends on cell type and its electrical impedance characteristics.
Collapse
Affiliation(s)
- D.A. Dean
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
| | - T. Ramanathan
- Mechanical Engineering Dept., Northwestern University, Evanston, IL-60208, e-mail:
| | - D. Machado
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
| | - R. Sundararajan
- Division of Pulmonary & Critical Care, Northwestern University Medical School, Chicago, IL-60611, e-mail:
- Electronics & Computer Engineering Technology, Arizona State University, Mesa, AZ-85212
| |
Collapse
|
46
|
Wagstaff KM, Jans DA. Nucleocytoplasmic transport of DNA: enhancing non-viral gene transfer. Biochem J 2007; 406:185-202. [PMID: 17680778 DOI: 10.1042/bj20070505] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Gene therapy, the correction of dysfunctional or deleted genes by supplying the lacking component, has long been awaited as a means to permanently treat or reverse many genetic disorders. To achieve this, therapeutic DNA must be delivered to the nucleus of cells using a safe and efficient delivery vector. Although viral-based vectors have been utilized extensively due to their innate ability to deliver DNA to intact cells, safety considerations, such as pathogenicity, oncogenicity and the stimulation of an immunological response in the host, remain problematical. There has, however, been much progress in the development of safe non-viral gene-delivery vectors, although they remain less efficient than the viral counterparts. The major limitations of non-viral gene transfer reside in the fact that it must be tailored to overcome the intracellular barriers to DNA delivery that viruses already master, including the cellular and nuclear membranes. In particular, nuclear transport of the therapeutic DNA is known to be the rate-limiting step in the gene-delivery process. Despite this, much progress had been made in recent years in developing novel means to overcome these barriers and efficiently deliver DNA to the nuclei of intact cells. This review focuses on the nucleocytoplasmic delivery of DNA and mechanisms to enhance to non-viral-mediated gene transfer.
Collapse
Affiliation(s)
- Kylie M Wagstaff
- Nuclear Signalling Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | | |
Collapse
|
47
|
Abstract
Despite nearly two decades of research, the successful application of systemically delivered non-viral gene therapies to treat human disease is still limited by poor transfection efficiency. The major barriers in the circulation and in the cell that limit transfection efficiency have been identified and the field has entered a phase of design and testing of more sophisticated carrier systems that attempt to circumvent these barriers. These studies are increasingly conducted in vivo using rapid quantitative measures of gene transfer efficiency as a guide. Although there has been steady progress in developing DNA nanoparticles that navigate the circulation, enter the target cell and escape lysosomal targeting, the final goal of efficiently traversing the nuclear membrane remains the most significant challenge. The ultimate goal is to develop elegant delivery systems that work in concert to deliver DNA from the needle to the nucleus.
Collapse
Affiliation(s)
- Garrett R Rettig
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, The University of Iowa, Iowa City, IA 52242, USA
| | | |
Collapse
|
48
|
Zhou R, Dean DA. Gene transfer of interleukin 10 to the murine cornea using electroporation. Exp Biol Med (Maywood) 2007; 232:362-9. [PMID: 17327469 PMCID: PMC4403727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
Gene therapy is a promising approach to deliver anti-inflammatory genes to the eye to treat a number of corneal diseases. We have used electroporation to deliver plasmids expressing interleukin 10 (IL-10) to the corneas of mice and evaluated the duration of expression following gene transfer. Unlike expression of reporter genes driven from the cytomegalovirus immediate early promoter (CMV(iep)), which remained high for 3 days, CMV(iep)-driven IL-10 expression peaked at Day 1 and decreased 2-fold each day thereafter. In an attempt to increase the duration of expression, the long-acting ubiquitin C (UbC) promoter was used but, surprisingly, a similar half-life of gene expression was observed. This reduced duration was not due to promoter inhibition by expressed IL-10 or clearance of plasmids from the cornea. However, when DNA nuclear targeting sequences (DTSs) that promote DNA nuclear import were removed from the plasmids, contrary to findings in nondividing cells and tissues in which these sequences are needed for gene transfer, robust expression was observed, and the duration increased significantly. Although corneal cell turnover was detected, suggesting mitosis-dependent plasmid nuclear localization independent of a DTS, the patterns of expressing and dividing cells appeared different. These results suggest that DNA nuclear targeting sequences may act differently in the cornea than in other tissues.
Collapse
Affiliation(s)
| | - David A. Dean
- To whom correspondence should be addressed at Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, 240 East Huron Avenue, McGaw 2336, Chicago, IL 60611.
| |
Collapse
|
49
|
Vaughan EE, DeGiulio JV, Dean DA. Intracellular trafficking of plasmids for gene therapy: mechanisms of cytoplasmic movement and nuclear import. Curr Gene Ther 2007; 6:671-681. [PMID: 17168698 PMCID: PMC4400175 DOI: 10.2174/156652306779010688] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Under physiologically relevant conditions, the levels of non-viral gene transfer are low at best. The reason for this is that many barriers exist for the efficient transfer of genes to cells, even before any gene expression can occur. While many transfection strategies focus on DNA condensation and overcoming the plasma membrane, events associated with the intracellular trafficking of the DNA complexes have not been as extensively studied. Once internalized, plasmids must travel potentially long distances through the cytoplasm to reach their next barrier, the nuclear envelope. This review summarizes the current progress on the cytoplasmic trafficking and nuclear transport of plasmids used for gene therapy applications. Both of these processes utilize specific and defined mechanisms to facilitate movement of DNA complexes through the cell. The continued elucidation and exploitation of these mechanisms will lead to improved strategies for transfection and successful gene therapy.
Collapse
Affiliation(s)
| | | | - David A. Dean
- Address correspondence to this author at the Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, 240 E. Huron Ave., McGaw M-300, Chicago IL 60611 USA; Tel: 312-503-3121; Fax: 312-908-4650;
| |
Collapse
|
50
|
Akita H, Hama S, Mizuguchi H, Harashima H. [Development of non-viral vector based on the quantitative comparison of intracellular trafficking with viral vector]. YAKUGAKU ZASSHI 2006; 126:1047-57. [PMID: 17077611 DOI: 10.1248/yakushi.126.1047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
For the development of efficient gene vector, intracellular processes such as cellular uptake, endosomal release and nuclear delivery must be overcome. Viruses have also evolved and have developed sophisticated mechanisms for controlling intracellular trafficking for the efficient delivery of their genomes to nuclei in host cells for symbiosis. In the light of these mechanisms, various kinds of artificial devices have been developed to overcome the intracellular barriers. However, in the majority of studies, variation of the transfection activity before and after the modification of devices was evaluated, and intracellular trafficking remained unclear. Therefore, it is understand to recognize which of the intracellular barrier should be intensively improved to enhance the transfection activity. To clarify the rate-limited process in the current non-viral vector, we compared the intracellular trafficking between adenovirus and LipofectAMINE PLUS. As a result, we found that difference of the transfection efficiency between adenovirus and LipofectAMINE PLUS was dominantly derived from the differences on transcription activity. Therefore it is essential to consider the regulation of the intranuclear events to improve the transfection activity of artificial vector.
Collapse
Affiliation(s)
- Hidetaka Akita
- Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12 Nishi-6, Kita-ku, Sapporo City 060-0812, Japan.
| | | | | | | |
Collapse
|