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Jiang N, Chen Q, Cao S, Hu B, Wang YJ, Zhou Q, Guo RQ. Ultrasound‑targeted microbubbles combined with a peptide nucleic acid binding nuclear localization signal mediate transfection of exogenous genes by improving cytoplasmic and nuclear import. Mol Med Rep 2017; 16:8819-8825. [PMID: 28990051 PMCID: PMC5779960 DOI: 10.3892/mmr.2017.7681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 03/01/2017] [Indexed: 11/29/2022] Open
Abstract
The development of an efficient delivery system is critical for the successful treatment of cardiovascular diseases using non-viral gene therapies. Cytoplasmic and nuclear membrane barriers reduce delivery efficiency by impeding the transfection of foreign genes. Thus, a gene delivery system capable of transporting exogenous genes may improve gene therapy. The present study used a novel strategy involving ultrasound-targeted microbubbles and peptide nucleic acid (PNA)-binding nuclear localization signals (NLS). Ultrasound-targeted microbubble destruction (UTMD) and PNA-binding NLS were used to improve the cytoplasmic and nuclear importation of the plasmid, respectively. Experiments were performed using antibody-targeted microbubbles (AT-MCB) that specifically recognize the SV40T antigen receptor expressed on the membranes of 293T cells, resulting in the localization of ultrasound microbubbles to 293T cell membranes. Furthermore, PNA containing NLS was inserted into the enhanced green fluorescent protein (EGFP)-N3 plasmid DNA (NLS-PNA-DNA), which increased nuclear localization. The nuclear import and gene expression efficiency of the AT-MCB with PNA-binding NLS were compared with AT-MCB alone or a PNA-binding NLS. The effect of the AT-MCB containing PNA-binding NLS on transfection was investigated. The ultrasound and AT-MCB delivery significantly enhanced the cytoplasmic intake of exogenous genes and maintained high cell viability. The nuclear import and gene expression of combined microbubble- and PNA-transfected cells were significantly greater compared with cells that were transfected with AT-MCB or DNA with only PNA-binding NLS. The quantity of EGFP-N3 plasmids in the nuclei was increased by >5.0-fold compared with control microbubbles (CMCB) and NLS-free plasmids. The gene expression was ~1.7-fold greater compared with NLS-free plasmids and 1.3-fold greater compared with control microbubbles. In conclusion, UTMD combined with AT-MCB and a PNA-binding NLS plasmid significantly improved transfection efficiency by increasing cytoplasmic and nuclear DNA import. This method is a promising strategy for the noninvasive and effective delivery of target genes or drugs for the treatment of cardiovascular diseases.
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Affiliation(s)
- Nan Jiang
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Qian Chen
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Sheng Cao
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Bo Hu
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Yi-Jia Wang
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Qing Zhou
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
| | - Rui-Qiang Guo
- Department of Ultrasound Imaging, Renmin Hospital of Wuhan University, Wuhan, Hubei 430060, P.R. China
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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.
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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
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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.
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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: 26] [Impact Index Per Article: 1.7] [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.
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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: 88] [Impact Index Per Article: 5.2] [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.
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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;
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Abstract
Until recently, the attention of most researchers has focused on the first and last steps of gene transfer, namely delivery to the cell and transcription, in order to optimise transfection and gene therapy. However, over the past few years, researchers have realised that the intracellular trafficking of plasmids is more than just a "black box" and is actually one of the major barriers to effective gene delivery. After entering the cytoplasm, following direct delivery or endocytosis, plasmids or other vectors must travel relatively long distances through the mesh of cytoskeletal networks before reaching the nuclear envelope. Once at the nuclear envelope, the DNA must either wait until cell division, or be specifically transported through the nuclear pore complex, in order to reach the nucleoplasm where it can be transcribed. This review focuses on recent developments in the understanding of these intracellular trafficking events as they relate to gene delivery. Hopefully, by continuing to unravel the mechanisms by which plasmids and other gene delivery vectors move throughout the cell, and by understanding the cell biology of gene transfer, superior methods of transfection and gene therapy can be developed.
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Affiliation(s)
- Rui Zhou
- Division of Pulmonary and Critical Care Medicine, Northwestern University, 240 E. Huron Avenue, McGaw 2336, Chicago IL 60611, USA
| | - R Christopher Geiger
- Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, 240 E. Huron Avenue, McGaw 2336, Chicago IL 60611, USA
| | - David A Dean
- Division of Pulmonary and Critical Care Medicine, Northwestern University, 240 E. Huron Avenue, McGaw 2336, Chicago IL 60611, USA
- Author for correspondence. Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, 240 E. Huron Avenue, McGaw 2336, Chicago, IL 60611, USA, Tel: +1 312 503 3121; Fax: +1 312 908 4650;
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Dean DA. Nonviral gene transfer to skeletal, smooth, and cardiac muscle in living animals. Am J Physiol Cell Physiol 2005; 289:C233-45. [PMID: 16002623 PMCID: PMC4152902 DOI: 10.1152/ajpcell.00613.2004] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The study of muscle physiology has undergone many changes over the past 25 years and has moved from purely physiological studies to those intimately intertwined with molecular and cell biological questions. To ask these questions, it is necessary to be able to transfer genetic reagents to cells both in culture and, ultimately, in living animals. Over the past 10 years, a number of different chemical and physical approaches have been developed to transfect living skeletal, smooth, and cardiac muscle systems with varying success and efficiency. This review provides a survey of these methods and describes some more recent developments in the field of in vivo gene transfer to these various muscle types. Both gene delivery for overexpression of desired gene products and delivery of nucleic acids for downregulation of specific genes and their products are discussed to aid the physiologist, cell biologist, and molecular biologist in their studies on whole animal biology.
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Affiliation(s)
- David A Dean
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern Univ., 240 E. Huron Ave., McGaw 2336, Chicago, IL 60611, USA.
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Abstract
Electroporation has proven to be a highly effective technique for the in vivo delivery of genes to a number of solid tissues. In most of the reported methods, DNA is injected into the target tissue and electrodes are placed directly on or in the tissue for application of the electric field. While this works well for solid tissues, there are many tissues and organs that are not amenable to such an approach. In this review I will focus on the development of electroporation protocols for two such tissues: the vasculature and the lung. Several methods for in vivo electroporation of the vasculature have been developed in recent years that deliver DNA to vessel segments from either the inside or outside of the vessel. The advantages and disadvantages of each are discussed, as are the applications for which they have been used. In more recent work, our laboratory has developed a novel method to deliver genes to the rodent lung that results in high level, uniform, gene expression throughout all cell types of the lung. Most importantly, this technique is safe, and causes no inflammatory response or alterations in normal physiology of the organs. Taken together, these studies demonstrate the utility of electroporation for gene transfer to non injectible tissues.
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Affiliation(s)
- David A Dean
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
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Nunamaker EA, Zhang HY, Shirasawa Y, Benoit JN, Dean DA. Electroporation-mediated delivery of catalytic oligodeoxynucleotides for manipulation of vascular gene expression. Am J Physiol Heart Circ Physiol 2003; 285:H2240-7. [PMID: 12881213 PMCID: PMC4400177 DOI: 10.1152/ajpheart.00350.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The development of inexpensive and effective approaches to transiently decrease gene expression in vivo would be useful for the study of physiological processes in living animals. DNAzymes are a novel class of DNA oligonucleotides that can catalytically cleave target mRNAs and thereby reduce protein production. However, current methods for their delivery in vivo are limited and inefficient. In this study, we show that electroporation can be used to deliver DNAzymes to the intact mesenteric vasculature of rats. With the use of PKC-epsilon as a target, a set of wild-type and mutant control DNAzymes was designed and shown to reduce both PKC-epsilon mRNA and protein levels in cultured smooth muscle cells in a specific manner. The wild-type DNAzyme reduced PKC-epsilon protein levels by 70% at 24 h in two different cell lines without decreasing the levels of the five other PKC isoforms tested. When delivered to the intact vasculature using electroporation, the DNAzyme reduced PKC-epsilon protein levels by >60% without affecting these other PKC isoforms. Electroporation was required for oligonucleotide transfer and was able to deliver the DNAzymes to multiple cell layers in the vessel wall. Protein levels were reduced maximally by 24 h postelectroporation and returned to normal by 48 h. These results suggest that electroporation can be used to deliver DNAzymes and other DNA oligonucleotides to the vasculature in vivo and can decrease gene expression for a window of time that can be used for experimental studies.
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Affiliation(s)
- Elizabeth A Nunamaker
- Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Avenue, Tarry 14-707, Chicago, IL 60611, USA
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