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Yamasaki Y, Kumekawa D, Yamauchi S, Omuro H. Re-examination of Peptide-Sequence-Dependent Gene Expression of Cysteine-Installed Pegylated Oligolysine/DNA Complexes. ACS OMEGA 2022; 7:15478-15487. [PMID: 35571853 PMCID: PMC9096824 DOI: 10.1021/acsomega.2c00122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
We previously synthesized cysteine-installed C-terminally PEGylated oligolysines with 20 amino acid residues to form cross-linked polymeric micelles (PMs) with luciferase-coding plasmid DNA as a candidate for artificial gene vectors. Luciferase gene expression in HeLa cells mediated by PEG-CK18C, PEG-CK9CK9, and PEG-K9CK9C was reported to be 35-, 5.4-, and 1.3-fold higher than that mediated by cysteine-uninstalled PEGylated oligolysine PEG-K20, respectively. However, after the publication, the survival rate of HeLa cells used in the previous study was found to be lower than usual when subcutaneously implanted into mice to create a xenograft model. In this study, to re-examine the peptide sequence-dependent gene expression, gene expression efficacy mediated by PEG-peptide PMs was compared with the PM cellular uptake results using newly obtained HeLa cell lines and the additional cell lines Huh-7, PANC-1, and BxPC3. As a result, PEG-K9CK9C PMs mediated the maximum gene expression in all cell lines, and the corresponding cellular uptake was also obtained. Therefore, we concluded that our previous results were erroneously obtained due to normality-depleted HeLa cells. A comparison of physicochemical characterizations, gene expression efficacy, and cellular uptake of PEG-peptide PMs is discussed in detail.
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Ueno M, Yamauchi S, Kumekawa D, Yamasaki Y. Peptide Sequence-Dependent Gene Expression of PEGylated Peptide/DNA Complexes. Mol Pharm 2019; 16:3072-3082. [PMID: 31173498 DOI: 10.1021/acs.molpharmaceut.9b00295] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Oligolysine-based PEG-peptides with 15 or 20 amino acid residues including two cysteines were synthesized to formulate cross-linked polyplex micelles (PMs) incorporating luciferase-coding plasmid DNA (pDNA). Two cysteine residues were separately allocated at the C-terminal, center, or N-terminal of peptide moieties. Although TEM observation showed that all PEG-peptides condensed pDNA into rod-like or toroidal morphologies, the rod length distribution of PMs was affected by both the amino acid sequence and the peptide length of PEG-peptides. In comparison to the cysteine-uninstalled PEG-peptides, the cysteine-installed PEG-peptides exhibited a reductive environment-responsive pDNA release, which was observed in a gel retardation assay. From physicochemical characterizations, a relationship between the amino acid sequence and the in vitro gene expression efficacy of PMs in a cell-free protein synthesis system has been clearly demonstrated. Finally, the cell-based assay using HeLa cells has been tested, and the differences between both results of cell-free and cell-based systems are discussed.
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Affiliation(s)
- Mikiko Ueno
- Department of Materials Engineering, Graduate School of Engineering , The University of Tokyo , Hongo 7-3-1 , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Satoshi Yamauchi
- Department of Materials Engineering, Graduate School of Engineering , The University of Tokyo , Hongo 7-3-1 , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Daiki Kumekawa
- Department of Materials Engineering, Graduate School of Engineering , The University of Tokyo , Hongo 7-3-1 , Bunkyo-ku, Tokyo 113-8656 , Japan
| | - Yuichi Yamasaki
- Department of Materials Engineering, Graduate School of Engineering , The University of Tokyo , Hongo 7-3-1 , Bunkyo-ku, Tokyo 113-8656 , Japan
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3
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Dong H, Meng X, Zheng X, Cheng X, Zheng Y, Zhao Y, Wu C. Design and Synthesis of Cross-Link-Dense Peptides by Manipulating Regioselective Bisthioether Cross-Linking and Orthogonal Disulfide Pairing. J Org Chem 2019; 84:5187-5194. [PMID: 30895794 DOI: 10.1021/acs.joc.9b00164] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Existing disulfide-rich peptides, both naturally occurring and de novo designed, only represent a tiny amount of the possible sequence space because natural evolution and de novo design only keep sequences that are structurally approachable by correct disulfide pairings. To bypass this limitation for designing new peptide scaffolds beyond the natural sequence space, we dedicate to developing novel disulfide-rich peptides with predefined disulfide pairing patterns irrelevant to primary sequences. However, most of these designed peptides still suffer from disulfide rearrangements to at least one to three possible isomers. Here, we report a general and reliable strategy for the design and synthesis of a range of structurally diverse cross-link-dense peptide (CDP) scaffolds with two orthogonal disulfide bonds and a bisthioether bridge that are not subject to disulfide isomerizations. Altering the pattern of cysteine and penicillamine generates hundreds of different CDP scaffolds tolerant to extensive sequence manipulations. This work thus provides many useful scaffolds for the design of functional molecules such as protein binders with improved proteolytic stability (e.g., designed by epitope grafting).
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Affiliation(s)
- Huilei Dong
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
| | - Xiaoting Meng
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
| | - Xiaoli Zheng
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
| | - Xueting Cheng
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
| | - Yiwu Zheng
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
| | - Yibing Zhao
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
| | - Chuanliu Wu
- Department of Chemistry, College of Chemistry and Chemical Engineering, State Key Laboratory of Physical Chemistry of Solid Surfaces, The MOE Key Laboratory of Spectrochemical Analysis and Instrumentation , Xiamen University , Xiamen 361005 , P.R. China
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Wang Y, Ye M, Xie R, Gong S. Enhancing the In Vitro and In Vivo Stabilities of Polymeric Nucleic Acid Delivery Nanosystems. Bioconjug Chem 2019; 30:325-337. [PMID: 30592619 PMCID: PMC6941189 DOI: 10.1021/acs.bioconjchem.8b00749] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Gene therapy holds great promise for various medical and biomedical applications. Nonviral gene delivery systems formed by cationic polymer and nucleic acids (e.g., polyplexes) have been extensively investigated for targeted gene therapy; however, their in vitro and in vivo stability is affected by both their intrinsic properties such as chemical compositions (e.g., polymer molecular weight and structure, and N/P ratio) and a number of environmental factors (e.g., shear stress during circulation in the bloodstream, interaction with the serum proteins, and physiological ionic strength). In this review, we surveyed the effects of a number of important intrinsic and environmental factors on the stability of polymeric gene delivery systems, and discussed various strategies to enhance the stability of polymeric gene delivery systems, thereby enabling efficient gene delivery into target cells. Future opportunities and challenges of polymeric nucleic acid delivery nanosystems were also briefly discussed.
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Affiliation(s)
- Yuyuan Wang
- Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
- Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
| | - Mingzhou Ye
- Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
| | - Ruosen Xie
- Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
- Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
| | - Shaoqin Gong
- Department of Materials Science and Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
- Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
- Department of Chemistry, University of Wisconsin–Madison, Madison, Wisconsin 53715, United States
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Yoshinaga N, Ishii T, Naito M, Endo T, Uchida S, Cabral H, Osada K, Kataoka K. Polyplex Micelles with Phenylboronate/Gluconamide Cross-Linking in the Core Exerting Promoted Gene Transfection through Spatiotemporal Responsivity to Intracellular pH and ATP Concentration. J Am Chem Soc 2017; 139:18567-18575. [PMID: 29188718 DOI: 10.1021/jacs.7b08816] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Polyplexes as gene delivery carriers require integrated functionalities to modulate intracellular trafficking for efficient gene transfection. Herein, we developed plasmid DNA (pDNA)-loaded polyplex micelles (PMs) from poly(ethylene glycol)-based block catiomers derivatized with 4-carboxy-3-fluorophenylboronic acid (FPBA) and d-gluconamide to form pH- and ATP-responsive cross-linking in the core. These PMs exhibited robustness in the extracellular milieu and smooth endosomal escape after cellular uptake, and they facilitated pDNA decondensation triggered by increased ATP concentration inside of the cell. Laser confocal microscopic observation revealed that FPBA installation enhanced the endosomal escapability of the PMs; presumably, this effect resulted from the facilitated endo-/lysosomal membrane disruption triggered by the released block catiomers with hydrophobic FPBA moieties in the side chain from the PM at lower pH condition of endo-/lysosomes. Furthermore, the profile of intracellular pDNA decondensation from the PMs was monitored using Förster resonance energy transfer measurement by flow cytometry; these observations confirmed that PMs optimized for ATP-responsivity exerted effective intracellular decondensation of loaded pDNA to attain promoted gene transfection.
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Affiliation(s)
- Naoto Yoshinaga
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takehiko Ishii
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Mitsuru Naito
- Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Taisuke Endo
- Department of Material Engineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Satoshi Uchida
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Horacio Cabral
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kensuke Osada
- Department of Bioengineering, Graduate School of Engineering, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kazunori Kataoka
- Innovation Center of NanoMedicine (iCONM), Kawasaki Institute of Industrial Promotion , 3-25-14 Tonomachi, Kawasaki-ku, Kawasaki, 210-0821, Japan.,Policy Alternatives Research Institute, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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6
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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.
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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.
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7
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Wang H, Cheng F, Li M, Peng W, Qu J. Reactivity and kinetics of vinyl sulfone-functionalized self-assembled monolayers for bioactive ligand immobilization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:3413-3421. [PMID: 25736428 DOI: 10.1021/la504087a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new vinyl sulfone (VS) disulfide, 1,2-bis(11-(vinyl sulfonyl)undecyl)disulfane, was synthesized to enable the preparation of VS-presenting self-assembled monolayers (VS SAMs) on Au substrates. The VS SAMs were used as a model system to assess the reaction kinetics of bioactive ligands, i.e., glutathione (GSH), N-(5-amino-1-carboxypentyl)iminodiacetic acid (ab-NTA), and mannose, toward the VS groups on the SAM surface. The VS SAMs and the ligand immobilization were characterized by X-ray photoelectron spectroscopy (XPS), contact angle goniometry, and protein-binding experiments using a quartz crystal microbalance (QCM). Kinetic studies showed that the surface VS groups undergo pseudo-first-order reactions with various ligands, with the observed rate constant being 0.057 min(-1) for GSH at pH 7.5, 0.011 min(-1) for ab-NTA at pH 8.5, and 0.009 min(-1) for mannose at pH 10.5. This work advanced our understanding of the reactivity of VS-bearing functional surfaces and further demonstrated the versatile potential of VS chemistry to prepare ligand-immobilized bioactive surfaces.
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Affiliation(s)
| | | | | | - Wei Peng
- §School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian, Liaoning 116023, People's Republic of China
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8
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Oupický D, Li J. Bioreducible polycations in nucleic acid delivery: past, present, and future trends. Macromol Biosci 2014; 14:908-22. [PMID: 24678057 PMCID: PMC4410047 DOI: 10.1002/mabi.201400061] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 02/19/2014] [Indexed: 12/16/2022]
Abstract
Polycations that are degradable by reduction of disulfide bonds are developed for applications in delivery of nucleic acids. This Feature Article surveys methods of synthesis of bioreducible polycations and discusses current understanding of the mechanism of action of bioreducible polyplexes. Emphasis is placed on the relationship between the biological redox environment and toxicity, trafficking, transfection activity, and in vivo behavior of bioreducible polycations and polyplexes.
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Affiliation(s)
- David Oupický
- Department of Pharmaceutical Sciences, Center for Drug Delivery and Nanomedicine, University of Nebraska Medical Center, Durham Research Center, 985830 Nebraska Medical Center, Omaha, NE 68198-5830, USA.
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9
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Kim SM, Yoon SM, Yim MS, Cho G, Ryu EK. Targeted delivery of a phosphopeptide prodrug inhibits the proliferation of a human glioma cell line. Amino Acids 2013; 45:1149-56. [PMID: 23907439 DOI: 10.1007/s00726-013-1570-5] [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] [Received: 04/26/2013] [Accepted: 07/23/2013] [Indexed: 01/27/2023]
Abstract
Peptides are ideal candidates for developing therapeutics. Polo-like kinase 1 is an important regulatory protein in the cell cycle and contains a C-terminal polo-box domain, which is the hallmark of this protein family. We developed a peptide inhibitor of polo-like kinase 1 that targets its polo-box domain. This new phosphopeptide, cRGDyK-S-S-CPLHSpT, preferentially penetrates the cancer cell membrane mediated by the integrin receptor, which is expressed at high levels by cancer cells. In the present study, using high performance liquid chromatography and mass spectroscopy, we determined the stability of cRGDyK-S-S-CPLHSpT and its cleavage by glutathione under typical conditions for cell culture. We further assessed the ability of the peptide to inhibit the proliferation of the U87MG glioma cell line. The phosphorylated peptide was stable, and the disulfide bond of cRGDyK-S-S-CPLHSpT was cleaved in 50 mM glutathione. This peptide inhibited the growth of cancer cells and changed their morphology. Therefore, we conclude that the phosphopeptide shows promise as a prodrug and has a high potential to act as an anticancer agent by inhibiting polo-like kinase 1 by binding its polo-box domain. These findings indicate the therapeutic potential of PLHSpT and peptides similarly targeted to surface receptors of cancer cells and to the functional domains of regulatory proteins.
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Affiliation(s)
- Sung-min Kim
- Division of Magnetic Resonance Research, Korea Basic Science Institute (KBSI), Chungbuk, Republic of Korea
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Yin L, Song Z, Kim KH, Zheng N, Gabrielson NP, Cheng J. Non-viral gene delivery via membrane-penetrating, mannose-targeting supramolecular self-assembled nanocomplexes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:3063-70. [PMID: 23417835 PMCID: PMC3757134 DOI: 10.1002/adma.201205088] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Indexed: 05/12/2023]
Abstract
Supramolecular self-assembled nanocomplexes (SSANs) capable of mannose receptor-mediated endocytosis and permeable to cellular and endosomal membranes are developed via the assembly of multiple rationally designed, function-specific materials. As a unique non-viral gene delivery vector, SSANs outperform commercial transfection reagents, including LPF2000, PEI, and jetPEI, by up to 2 orders of magnitude.
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Affiliation(s)
- Lichen Yin
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W Green St, Urbana, IL 61801, USA
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11
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Ericson MD, Rice KG. Synthesis of homogenous disulfide cross-linked polypeptides by iterative reducible ligation. Biopolymers 2013. [PMID: 23203756 DOI: 10.1002/bip.22117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A new method of directed solution phase synthesis of polypeptides linked through iterative formation of disulfide bonds is reported. Four dodecapeptides were successfully ligated into a single 48 amino acid polypeptide using an N-terminal Fmoc-thiazolidine and a novel acidic silver trifluoromethanesulfonate thiazolidine hydrolysis to achieve efficient ligation in the presence of internal disulfide bonds. The approach allows the synthesis of homogeneous disulfide cross-linked polypeptides that have application in gene delivery by undergoing a reductively triggered release of DNA.
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Affiliation(s)
- Mark D Ericson
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, IA 52242, USA
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12
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Alexander C, Fernandez Trillo F. Bioresponsive Polyplexes and Micelleplexes. SMART MATERIALS FOR DRUG DELIVERY 2013. [DOI: 10.1039/9781849736800-00256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The delivery of nucleic acids (NAs) is hindered by several factors, such as the size of the biomolecule (micron size for plasmid DNA), the presence of different biological barriers or the degradation of NAs. Most of these limitations are avoided by complexation with polycationic species, which collapse NAs into nanometer-sized polyplexes that can be efficiently internalized into the target cells. Because there are subtle changes in physiological conditions, such as the drop in pH at the endosome, or the increase in temperature in tumor tissue, stimuli responsive synthetic polymers are ideal candidates for the synthesis of efficient gene delivery vehicles. In this chapter, representative examples of “smart” polypexes that exploit these changes in physiological environment for the delivery of NAs are described, and the transfection efficiency of pH-, redox-, temperature- and light-responsive polyplexes is analyzed.
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Patnaik S, Gupta KC. Novel polyethylenimine-derived nanoparticles for in vivo gene delivery. Expert Opin Drug Deliv 2012; 10:215-28. [PMID: 23252504 DOI: 10.1517/17425247.2013.744964] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Branched and linear polyethylenimines (PEIs) are cationic polymers that have been used to deliver nucleic acids both in vitro and in vivo. Owing to the high cationic charge, the branched polymers exhibit high transfection efficiency, and particularly PEI of molecular weight 25 kDa is considered as a gold standard in gene delivery. These polymers have been extensively studied and modified with different ligands so as to achieve the targeted delivery. AREAS COVERED The application of PEI in vivo promises to take the polymer-based vector to the next level wherein it can undergo clinical trials and subsequently could be used for delivery of therapeutics in humans. This review focuses on the various recent developments that have been made in the field of PEI-based delivery vectors for delivery of therapeutics in vivo. EXPERT OPINION The efficacy of PEI-based delivery vectors in vivo is significantly high and animal studies demonstrate that such systems have a potential in humans. However, we feel that though PEI is a promising vector, further studies involving PEI in animal models are needed so as to get a detailed toxicity profile of these vectors. Also, it is imperative that the vector reaches the specific organ causing little or no undesirable effects to other organs.
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Affiliation(s)
- Soma Patnaik
- CSIR-Indian Institute of Toxicology Research, M.G. Marg, Lucknow, 226 001, India
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14
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Kim BK, Kang H, Doh KO, Lee SH, Park JW, Lee SJ, Lee TJ. Homodimeric SV40 NLS peptide formed by disulfide bond as enhancer for gene delivery. Bioorg Med Chem Lett 2012; 22:5415-8. [PMID: 22871581 DOI: 10.1016/j.bmcl.2012.07.051] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 07/10/2012] [Accepted: 07/12/2012] [Indexed: 10/28/2022]
Abstract
Recently, cysteine residue incorporation increased liposome-mediated transfection compared to unmodified peptide. Therefore, we designed novel modified SV40 NLS peptides, homodimeric (NLS-CTHD, NLS-NTHD) and closed structure (cyclic NLS), simply using disulfide bond between cysteines to develop more efficient and safe non-viral gene delivery system. The simple mix of NLS-CTHD among these novel transfection enhancing peptides with DNA increased the gene transfer potency of cationic liposomes more efficiently with no additional cytotoxicity.
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Affiliation(s)
- Bieong-Kil Kim
- Department of Physiology, College of Medicine, Yeungnam University, Daegu 705-717, Republic of Korea
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15
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Son S, Namgung R, Kim J, Singha K, Kim WJ. Bioreducible polymers for gene silencing and delivery. Acc Chem Res 2012; 45:1100-12. [PMID: 22129162 DOI: 10.1021/ar200248u] [Citation(s) in RCA: 211] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Polymeric gene delivery vectors show great potential for the construction of the ideal gene delivery system. These systems harness their ability to incorporate versatile functional traits to overcome most impediments encountered in gene delivery: from the initial complexation to their target-specific release of the therapeutic nucleic acids at the cytosol. Among the numerous multifunctional polymers that have been designed and evaluated as gene delivery vectors, polymers with redox-sensitive (or bioreducible) functional domains have gained great attention in terms of their structural and functional traits. The redox environment plays a pivotal role in sustaining cellular homeostasis and natural redox potential gradients exist between extra- and intracellular space and between the exterior and interior of subcellular organelles. In some cases, researchers have designed the polymeric delivery vectors to exploit these gradients. For example, researchers have taken advantage of the high redox potential gradient between oxidizing extracellular space and the reducing environment of cytosolic compartments by integrating disulfide bonds into the polymer structure. Such polymers retain their cargo in the extracellular space but selectively release the therapeutic nucleic acids in the reducing space within the cytosol. Furthermore, bioreducible polymers form stable complex with nucleic acids, and researchers can fabricate these structures to impart several important features such as site-, timing-, and duration period-specific gene expression. Additionally, the introduction of disulfide bonds within these polymers promotes their biodegradability and limits their cytotoxicity. Many approaches have demonstrated the versatility of bioreducible gene delivery, but the underlying biological rationale of these systems remains poorly understood. The process of disulfide reduction depends on multiple variables in the cellular redox environment. Therefore, the quest to unravel various issues such as the site and time of disulfide bond reduction during the cellular uptake and trafficking have stimulated a number of interesting studies which have employed disulfide compounds with a variety of reducible linkers. Such studies help researchers understand not only how modifications made to disulfides can alter their thiol-disulfide exchange characteristics but also to decipher the effect of the induced changes on the dynamics of the redox environment. This Account discusses current research trends and recent progress in the disulfide chemistry enabling novel and versatile designs of reducible polymeric gene delivery systems. We present strategies for the introduction of disulfide bonds into polymers. These representative examples and their respective outcomes elaborate the benefit and efficiency of disulfides at the individual stages of gene delivery.
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Affiliation(s)
- Sejin Son
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Ran Namgung
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Jihoon Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kaushik Singha
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Won Jong Kim
- Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, Korea
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16
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He C, Zhuang X, Tang Z, Tian H, Chen X. Stimuli-sensitive synthetic polypeptide-based materials for drug and gene delivery. Adv Healthc Mater 2012. [PMID: 23184687 DOI: 10.1002/adhm.201100008] [Citation(s) in RCA: 262] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Stimuli-sensitive synthetic polypeptides are unique biodegradable and biocompatible synthetic polymers with structures mimicking natural proteins. These polymers exhibit reversible secondary conformation transitions and/or hydrophilic-hydrophobic transitions in response to changes in environmental conditions such as pH and temperature. The stimuli-triggered conformation and/or phase transitions lead to unique self-assembly behaviors, making these materials interesting for controlled drug and gene delivery applications. Therefore, stimuli-sensitive synthetic polypeptide-based materials have been extensively investigatid in recent years. Various polypeptide-based materials, including micelles, vesicles, nanogels, and hydrogels, have been developed and tested for drug- and gene-delivery applications. In addition, the presence of reactive side groups in some polypeptides facilitates the incorporation of various functional moieties to the polypeptides. This Review focuses on recent advances in stimuli-sensitive polypeptide-based materials that have been designed and evaluated for drug and gene delivery applications. In addition, recent developments in the preparation of stimuli-sensitive functionalized polypeptides are discussed.
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Affiliation(s)
- Chaoliang He
- Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, PR China
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Bennevault-Celton V, Urbach A, Martin O, Pichon C, Guégan P, Midoux P. Supramolecular assemblies of histidinylated α-cyclodextrin in the presence of DNA scaffold during CDplexes formation. Bioconjug Chem 2011; 22:2404-14. [PMID: 22014097 DOI: 10.1021/bc200167p] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
α-Cyclodextrin was transformed in a cationic unit after per substitution with histidine (His-α-CD) and lysine (Lys-α-CD) molecules on the primary face. His-α-CD and Lys-α-CD were used to form electrostatic complexes (CDplexes) with a plasmid DNA encoding luciferase gene, and the ability of CDplexes to transfect mammalian cells was examined using HEK293-T7 cells. The luciferase activity in cells transfected with His-α-CDplexes was 8-fold higher than that obtained Lys-α-CDplexes. When the transfection was carried out in the presence of chloroquine, the luciferase activity with His-α-CDplexes and Lys-α-CDplexes increased 6 and 25 times, respectively. The lower enhancement with His-α-CDplexes confirmed that histidine induced a proton sponge effect inside endosomes upon imidazole protonation, favoring DNA delivery in the cytosol. At the same time, we found that the condensation of DNA with His-α-CD was unexpectedly stronger than that obtained with the lysyl-α-CD counterpart. Moreover, it was as strong as that observed with high molecular weight polylysine. NMR (ROESY and DOSY) investigations in the absence of DNA showed that an inclusion complex is formed between the imidazole ring of histidine and the hydrophobic cavity of CD but no His-α-CD polymers can be formed by intermolecular interactions. These results suggest that intermolecular interactions between imidazole and His-α-CD cavity could be involved to form supramolecular assemblies in the presence of a DNA scaffold leading to DNA condensation into low diameter particles.
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Shirazi RS, Ewert KK, Leal C, Majzoub RN, Bouxsein NF, Safinya CR. Synthesis and characterization of degradable multivalent cationic lipids with disulfide-bond spacers for gene delivery. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2156-66. [PMID: 21640069 DOI: 10.1016/j.bbamem.2011.04.020] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Revised: 04/04/2011] [Accepted: 04/12/2011] [Indexed: 11/25/2022]
Abstract
Gene therapy provides powerful new approaches to curing a large variety of diseases, which are being explored in ongoing worldwide clinical trials. To overcome the limitations of viral gene delivery systems, synthetic nonviral vectors such as cationic liposomes (CLs) are desirable. However, improvements of their efficiency at reduced toxicity and a better understanding of their mechanism of action are required. We present the efficient synthesis of a series of degradable multivalent cationic lipids (CMVLn, n=2 to 5) containing a disulfide bond spacer between headgroup and lipophilic tails. This spacer is designed to be cleaved in the reducing milieu of the cytoplasm and thus decrease lipid toxicity. Small angle X-ray scattering demonstrates that the initially formed lamellar phase of CMVLn-DNA complexes completely disappears when reducing agents such as DTT or the biologically relevant reducing peptide glutathione are added to mimic the intracellular milieu. The CMVLs (n=3 to 5) exhibit reduced cytotoxicity and transfect mammalian cells with efficiencies comparable to those of highly efficient non-degradable analogs and benchmark commercial reagents such as Lipofectamine 2000. Thus, our results demonstrate that degradable disulfide spacers may be used to reduce the cytotoxicity of synthetic nonviral gene delivery carriers without compromising their transfection efficiency.
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Affiliation(s)
- Rahau S Shirazi
- Chemistry and Biochemistry Department, University of California, Santa Barbara, CA 93106, USA
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Baumhover NJ, Anderson K, Fernandez CA, Rice KG. Synthesis and in vitro testing of new potent polyacridine-melittin gene delivery peptides. Bioconjug Chem 2010; 21:74-83. [PMID: 19968269 DOI: 10.1021/bc9003124] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The combination of a polyacridine peptide modified with a melittin fusogenic peptide results in a potent gene transfer agent. Polyacridine peptides of the general formula (Acr-X)(n)-Cys were prepared by solid-phase peptide synthesis, where Acr is Lys modified on its epsilon-amine with acridine, X is Arg, Leu, or Lys and n is 2, 3, or 4 repeats. The Cys residue was modified by either a maleimide-melittin or a thiolpyridine-Cys-melittin fusogenic peptide resulting in reducible or non-reducible polyacridine-melittin peptides. Hemolysis assays established that polyacridine-melittin peptides retained their membrane lytic potency relative to melittin at pH 7.4 and 5. When combined with plasmid DNA, the membrane lytic potency of polyacridine-melittin peptides was neutralized. Gene transfer experiments in multiple cell lines established that polyacridine-melittin peptides mediate expression as efficiently as PEI. The expression was very dependent upon a disulfide bond linking polyacridine to melittin. The gene transfer was most efficient when X is Arg and n is 3 or 4 repeats. These studies establish polyacridine peptides as a novel DNA binding anchor peptide.
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Abstract
Linking genes with the underlying mechanisms of diseases is one of the biggest challenges of genomics-driven drug discovery research. Designing an inhibitor for any neurodegenerative disease that effectively halts the pathogenicity of the disease is yet to be achieved. The challenge lies in crossing the blood-brain barrier (BBB)/blood-cerebrospinal fluid barrier (BCSFB) to reach the catalytic pockets of the enzyme/protein involved in the molecular mechanism of the disease process. Designing siRNA with exquisite specificity may result in selective suppression of the disease-linked gene. Although siRNA is the most promising method, it loses its potency in downregulating the gene due to its inherent instability, off-target effects, and lack of on-target effective delivery systems. Viral as well as nonviral delivery methods have been effectively tested in vivo for silencing of molecular targets and have resulted in significant efficacy in animal models of Alzheimer's disease, amyotrophic lateral sclerosis (ALS), anxiety, depression, encephalitis, glioblastoma, Huntington's disease, neuropathic pain, and spinocerebellar ataxia. To realize the full therapeutic potential of siRNA for neurodegenerative diseases, we need to overcome many hurdles and challenges such as selecting suitable tissue-specific delivery vectors, minimizing the off-target effects, and achieving distribution in sufficient concentrations at the target tissue without any side effects. Cationic nanoparticle-mediated targeted siRNA delivery for therapeutic purposes has gained considerable clinical importance as a result of its promising efficacy.
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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.
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Affiliation(s)
- Christian A Fernandez
- Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, USA
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Bauhuber S, Hozsa C, Breunig M, Göpferich A. Delivery of nucleic acids via disulfide-based carrier systems. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2009; 21:3286-3306. [PMID: 20882498 DOI: 10.1002/adma.200802453] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Nucleic acids are not only expected to assume a pivotal position as "drugs" in the treatment of genetic and acquired diseases, but could also act as molecular cues to control the microenvironment during tissue regeneration. Despite this promise, the efficient delivery of nucleic acids to their side of action is still the major hurdle. One among many prerequisites for a successful carrier system for nucleic acids is high stability in the extracellular environment, accompanied by an efficient release of the cargo in the intracellular compartment. A promising strategy to create such an interactive delivery system is to exploit the redox gradient between the extra- and intracellular compartments. In this review, emphasis is placed on the biological rationale for the synthesis of redox sensitive, disulfide-based carrier systems, as well as the extra- and intracellular processing of macromolecules containing disulfide bonds. Moreover, the basic synthetic approaches for introducing disulfide bonds into carrier molecules, together with examples that demonstrate the benefit of disulfides at the individual stages of nucleic acid delivery, will be presented.
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Abstract
Polyplexes sensitive to redox potential gradients represent a promising class of vectors for delivery of nucleic acids. This review focuses on the recent advances in the development of these vectors. The biological rationale for the design of redox-sensitive polyplexes is discussed together with the basic synthetic approaches for introducing reducible disulfide bonds into the structure of the polyplexes. The biological properties of the redox-sensitive polyplexes of plasmid DNA, mRNA, antisense oligonucleotides and siRNA are reviewed with emphasis on in vitro cellular delivery, cytotoxicity and in vivo activity. Overall, redox-sensitive polyplexes represent a promising platform for further development as vectors for delivery of a wide variety of therapeutic nucleic acids.
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Stevenson M, Ramos-Perez V, Singh S, Soliman M, Preece JA, Briggs SS, Read ML, Seymour LW. Delivery of siRNA mediated by histidine-containing reducible polycations. J Control Release 2008; 130:46-56. [PMID: 18571758 DOI: 10.1016/j.jconrel.2008.05.014] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 05/06/2008] [Accepted: 05/09/2008] [Indexed: 10/22/2022]
Abstract
Histidine containing reducible polycations based on CH(6)K(3)H(6)C monomers (His6 RPCs), are highly effective DNA transfection agents combining pH buffering endosomal escape mechanisms with rapid unpackaging following reduction in the cytoplasm. We examined their ability to mediate siRNA uptake into cells focusing on hepatocyte delivery. Co-delivery of EGFP siRNA with pEGFP plasmid DNA reduced reporter gene expression by 85%. However while DNA transfection efficiency increased with polymer size, with 162 k His6 RPCs proving the most effective, delivery of siRNA alone to EGFP stably expressing cells was only possible using 36-80 k polymers. Analysis of particle sizes showed that 80 k polymers formed more compact siRNA complexes than 162 k polymers. The reducible nature of the polymer was necessary for siRNA activity, since siRNA combined with non-reducible polylysine showed little activity. Incorporation of a targeting peptide from the Plasmodium falciparum circumsporozoite (CS) protein onto His6 RPCs, significantly improved transfection of plasmid DNA and siRNA activity in hepatocytes, but not in most non-liver cells tested. siRNA targeted to the hepatitis B virus surface antigen delivered by CS-His6 RPC, mediated falls in both mRNA and protein expression, suggesting that this delivery system could be developed for potential therapies for viral hepatitis.
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Affiliation(s)
- Mark Stevenson
- Department of Clinical Pharmacology, University of Oxford, Old Road Campus, Oxford OX3 7DQ, UK.
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Prakash S, Malhotra M. Recent Advancements in Targeted Delivery of Therapeutic Molecules in Neurodegenerative Disease–-Spinocerebellar Ataxia–-Opportunities and Challenges. Drug Target Insights 2008. [DOI: 10.4137/dti.s378] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Satya Prakash
- Biomedical Technology and Cell Therapy Research Laboratory, Departments of Biomedical Engineering and Physiology, Artificial Cells and Organs Research Center, Faculty of Medicine, McGill University, 3775 University Street, Montreal, Quebec, H3A 2B4, Canada
| | - Meenakshi Malhotra
- Biomedical Technology and Cell Therapy Research Laboratory, Departments of Biomedical Engineering and Physiology, Artificial Cells and Organs Research Center, Faculty of Medicine, McGill University, 3775 University Street, Montreal, Quebec, H3A 2B4, Canada
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Borbas KE, Kee HL, Holten D, Lindsey JS. A compact water-soluble porphyrin bearing an iodoacetamido bioconjugatable site. Org Biomol Chem 2008; 6:187-94. [DOI: 10.1039/b715072e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Hao J, Kwissa M, Pulendran B, Murthy N. Peptide crosslinked micelles: a new strategy for the design and synthesis of peptide vaccines. Int J Nanomedicine 2007; 1:97-103. [PMID: 17722267 PMCID: PMC2426769 DOI: 10.2147/nano.2006.1.1.97] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
This report presents a new and simple methodology for the synthesis of multicomponent peptide vaccines, named the peptide crosslinked micelles (PCMs). The PCMs are core shell micelles designed to deliver peptide antigens and immunostimulatory DNA to antigen-presenting cells (APCs). They are composed of immunostimulatory DNA, peptide antigen, and a thiopyridal derived poly(ethylene glycol)-polylysine block copolymer. The peptide antigen acts as a crosslinker in the PCM strategy, which allows the peptide antigen to be efficiently encapsulated into the PCMs and also stabilizes them against degradation by serum components. Cell culture studies demonstrated that the PCMs greatly enhance the uptake of peptide antigens into human dendritic cells.
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Affiliation(s)
- Jihua Hao
- Georgia Institute of Technology, Department of Biomedical EngineeringAtlanta, GA, USA
| | - Marcin Kwissa
- Emory Vaccine Center, Department of PathologyAtlanta, GA, USA
| | - Bali Pulendran
- Emory Vaccine Center, Department of PathologyAtlanta, GA, USA
| | - Niren Murthy
- Georgia Institute of Technology, Department of Biomedical EngineeringAtlanta, GA, USA
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Srinivasachari S, Liu Y, Zhang G, Prevette L, Reineke TM. Trehalose click polymers inhibit nanoparticle aggregation and promote pDNA delivery in serum. J Am Chem Soc 2007; 128:8176-84. [PMID: 16787082 DOI: 10.1021/ja0585580] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Herein, three new glycopolymers have been synthesized via "click polymerization" to promote nucleic acid delivery in the presence of biological media containing serum. These structures were designed to contain a trehalose moiety to promote biocompatibility, water solubility, and stability against aggregation, amide-triazole groups to enhance DNA binding affinity, and an oligoamine unit to facilitate DNA encapsulation, phosphate neutralization, and interactions with cell surfaces. A 2,3,4,2',3',4'-hexa-O-acetyl-6,6'-diazido-6,6'-dideoxy-D-trehalose (4) monomer was polymerized via copper(I)-catalyzed azide-alkyne cycloaddition with a series of dialkyne-amide comonomers that contain either one, two, or three Boc-protected secondary amines (7a, 7b, or 7c, respectively). After deprotection, three water-soluble polycations (9a, 9b, or 9c) were obtained with similar degrees of polymerization (n = 56-61) to elucidate the role of amine number on nucleic acid binding, complex formation, stability, and cellular delivery. Gel electrophoresis and ethidium bromide experiments showed that 9a-9c associated with plasmid DNA (pDNA) and formed complexes (polyplexes) at N/P ratios dependent on the amine number. TEM experiments revealed that 9a-9c polyplexes were small (50-120 nm) and had morphologies (spherical and rodlike) associated with the polymer chain stiffness. Dynamic light scattering studies in the presence of media containing serum demonstrated that 9c polyplexes had a low degree of flocculation, whereas 9a and 9b polyplexesd aggregate rapidly. Further biological studies revealed that these structures were biocompatible and deliver pDNA into HeLa cells. Particularly, 9c polyplexes promoted high delivery efficacy and gene expression profiles in the presence of serum.
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Parker AL, Eckley L, Singh S, Preece JA, Collins L, Fabre JW. (LYS)(16)-based reducible polycations provide stable polyplexes with anionic fusogenic peptides and efficient gene delivery to post mitotic cells. Biochim Biophys Acta Gen Subj 2007; 1770:1331-7. [PMID: 17651899 DOI: 10.1016/j.bbagen.2007.06.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 06/14/2007] [Accepted: 06/15/2007] [Indexed: 01/05/2023]
Abstract
Extracellular stability, endocytic escape, intracellular DNA release and nuclear translocation of DNA are all critical properties of non-viral vector/DNA particles. We have evaluated a (Lys)(16)-based linear, reducible polycation (RPC) in combination with an acid-dependent, anionic fusogenic peptide for gene delivery to dividing and post-mitotic cells. The RPC was formed from Cys(Lys)(16)Cys monomers. Molecular weight was 24,000 Da, corresponding to an average of 10.5 peptide monomers per RPC. Non-reducible polylysine (PLL) (27,000 Da) and monomeric (Lys)(16) peptide were evaluated for comparison. (Lys)(16)/DNA particles were disrupted at fusogenic peptide concentrations well below those used for gene delivery. By contrast, RPC/DNA an PLL/DNA particles were stable in the presence of high concentrations of the anionic peptide. Addition of 10% serum virtually abolished the transfection ability of (Lys)(16)/DNA/fusogenic peptide particles, but had little effect on RPC/DNA/fusogenic peptide particles. RPC/DNA/fusogenic peptide particles were highly effective for gene delivery to both cell lines and post-mitotic corneal endothelium. PLL/DNA/fusogenic peptide particles were moderately effective on cell lines, but gave no gene delivery with corneal endothelial cells. We conclude that (Lys)(16)-based RPC/DNA/fusogenic peptide particles provide a gene delivery system which is potentially stable in the extracellular environment and, on reductive depolymerisation, can release DNA plasmids for nuclear translocation.
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Affiliation(s)
- Alan L Parker
- Department of Clinical Sciences King's College London School of Medicine The Rayne Institute 123 Coldharbour Lane, London SE5 9NU, UK
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30
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You YZ, Manickam DS, Zhou QH, Oupický D. A versatile approach to reducible vinyl polymers via oxidation of telechelic polymers prepared by reversible addition fragmentation chain transfer polymerization. Biomacromolecules 2007; 8:2038-44. [PMID: 17518443 DOI: 10.1021/bm0702049] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ye-Zi You
- Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48202, USA
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Chen CP, Kim JS, Liu D, Rettig GR, McAnuff MA, Martin ME, Rice KG. Synthetic PEGylated glycoproteins and their utility in gene delivery. Bioconjug Chem 2007; 18:371-8. [PMID: 17373767 PMCID: PMC2653852 DOI: 10.1021/bc060229p] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PEGylated glycoproteins (PGPs) were synthesized by copolymerizing a Cys-terminated PEG-peptide, glycopeptide, and melittin peptide. Compositionally unique PGPs were prepared by varying the ratio of PEG-peptide (20-90%) and melittin (0-70%) with a constant amount of glycopeptide (10%). The PGPs were purified by RP-HPLC, and characterized for molecular weight and polydispersity by GPC-HPLC and SDS-PAGE and for composition by RP-HPLC following reduction to form monomeric peptides. PGPs formed DNA condensates of 200-300 nm in diameter that were administered to mice via the tail vein. Biodistribution studies confirmed their primary targeting to liver hepatocytes with a DNA metabolic half-life of 1 h. Upon stimulation by hydrodynamic dosing with saline, PGP DNA (5 microg) mediated luciferase expression in the liver detected by bioluminescence imaging (BLI) after 24 h. The level of gene expression mediated by PGP DNA was 5000-fold less than direct hydrodynamic dosing of an equivalent amount of DNA and was independent of the mol percent of melittin incorporated into the polymer, but dependent on the presence of galactose on PGP. The results establish the ability to prepare three-component gene delivery polymers that function in vivo. Further design improvements in fusogenic peptides for gene delivery and for the simultaneous use of a nuclear targeting strategy will be necessary to approach levels of expression mediated by the direct hydrodynamic dosing of DNA.
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Affiliation(s)
| | | | | | | | | | | | - Kevin G. Rice
- To whom correspondence should be addressed: , Tel: 319-335-9903 Fax: 319-335-8766
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Neu M, Germershaus O, Mao S, Voigt KH, Behe M, Kissel T. Crosslinked nanocarriers based upon poly(ethylene imine) for systemic plasmid delivery: In vitro characterization and in vivo studies in mice. J Control Release 2007; 118:370-80. [PMID: 17316863 DOI: 10.1016/j.jconrel.2007.01.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 01/11/2007] [Accepted: 01/15/2007] [Indexed: 10/23/2022]
Abstract
Crosslinked poly(ethylene imine) (PEI) polyplexes for intracellular DNA release were generated using a low molecular weight crosslinking reagent, Dithiobis(succinimidyl propionate) (DSP). Disulfide bonds of the crosslinked polyplexes were susceptible to intracellular redox conditions and DNA release was observed using an ethidium bromide exclusion assay and dynamic light scattering. Transfection experiments were performed to elucidate the effect of extra- and intracellular redox conditions. Pharmacokinetics and organ accumulation of uncrosslinked and crosslinked polyplexes were compared and gene expression patterns were measured in mice 24 h after intravenous injection. Crosslinked PEI and plasmid DNA formed stable polyplexes in a size range of 100-300 nm, with zeta potentials between +16.4 and +26.1 mV. DNA release occurred after cleavage of the disulfide bonds. Cell culture experiments under reducing conditions as well as with glutathione loaded cells confirmed the proposed intracellular activation. A significant influence of the intracellular glutathione status on the transfection efficiency was observed. Pharmacokinetic profiles of crosslinked PEI/DNA polyplexes in mice after intravenous administration showed higher blood levels for crosslinked polyplexes. These polyplexes accumulated mainly in the liver and the lungs. In vivo transfection data revealed significantly reduced (unwanted) lung transfection while liver transfection predominated. These studies suggest that crosslinked polyplexes are more stable in circulation and retain their transfection efficiency after intravenous administration.
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Affiliation(s)
- Michael Neu
- Department of Pharmaceutics and Biopharmacy, Philipps Universität, Ketzerbach 63, Marburg, Germany
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Chen J, Huang SW, Lin WH, Zhuo RX. Tunable film degradation and sustained release of plasmid DNA from cleavable polycation/plasmid DNA multilayers under reductive conditions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2007; 3:636-43. [PMID: 17351989 DOI: 10.1002/smll.200600301] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The controllable and sustained release of DNA from the surfaces of biomaterials or biomedical devices represents a new method for localized gene delivery. We report the synthesis of a novel polycation containing disulfide bonds in its backbone and the fabrication of polycation/plasmid DNA multilayered thin films by layer-by-layer assembly. The films are very stable during preparation and in storage, however, they gradually degrade and release the incorporated DNA when incubated in PBS buffer containing dithiothreitol (DTT), which results from the degradation of a disulfide-contained polymer under reductive conditions. The film degradation rate and DNA release rate can be tuned by the concentration of reducing agent. This approach will be useful in gene therapy and tissue engineering by controlled administration of therapeutic DNA deposited on the surface of implantable biomedical devices or tissue engineering scaffolds.
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Affiliation(s)
- Jun Chen
- Key Laboratory of Biomedical Polymers, Ministry of Education, Department of Chemistry, Wuhan University, Wuhan 430072, PR China
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Neu M, Fischer D, Kissel T. Recent advances in rational gene transfer vector design based on poly(ethylene imine) and its derivatives. J Gene Med 2007; 7:992-1009. [PMID: 15920783 DOI: 10.1002/jgm.773] [Citation(s) in RCA: 649] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The continually increasing wealth of knowledge about the role of genes involved in acquired or hereditary diseases renders the delivery of regulatory genes or nucleic acids into affected cells a potentially promising strategy. Apart from viral vectors, non-viral gene delivery systems have recently received increasing interest, due to safety concerns associated with insertional mutagenesis of retro-viral vectors. Especially cationic polymers may be particularly attractive for the delivery of nucleic acids, since they allow a vast synthetic modification of their structure enabling the investigation of structure-function relationships. Successful clinical application of synthetic polycations for gene delivery will depend primarily on three factors, namely (1) an enhancement of the transfection efficiency, (2) a reduction in toxicity and (3) an ability of the vectors to overcome numerous biological barriers after systemic or local administration. Among the polycations presently used for gene delivery, poly(ethylene imine), PEI, takes a prominent position, due to its potential for endosomal escape. PEI as well as derivatives of PEI currently under investigation for DNA and RNA delivery will be discussed. This review focuses on structure-function relationships and the physicochemical aspects of polyplexes which influence basic characteristics, such as complex formation, stability or in vitro cytotoxicity, to provide a basis for their application under in vivo conditions. Rational design of optimized polycations is an objective for further research and may provide the basis for a successful cationic polymer-based gene delivery system in the future.
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Affiliation(s)
- Michael Neu
- Department of Pharmaceutics and Biopharmacy, Philipps University, Ketzerbach 63, 35037 Marburg, Germany
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Neu M, Sitterberg J, Bakowsky U, Kissel T. Stabilized Nanocarriers for Plasmids Based Upon Cross-linked Poly(ethylene imine). Biomacromolecules 2006; 7:3428-38. [PMID: 17154471 DOI: 10.1021/bm060788z] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stabilized PEI/DNA polyplexes were generated by cross-linking PEI with biodegradable disulfide bonds. The reaction conversion of different PEIs with the amine reactive cross-linker dithiobis(succinimidyl propionate) (DSP) was investigated, and the molecular weight of the reaction products was identified. Light scattering and microelectrophoresis were employed to assess size and zeta potential of the resulting polyplexes. Polyplex morphology and mechanic stability were investigated using atomic force microscopy. Finally, albumin and erythrocyte interactions and stability against polyanions and high ionic strength were checked. Polyplexes of PEI and DNA were prepared by two different formulation methods, either using pre-cross-linked polymers or by cross-linking polyplexes after complexation. Only the latter method yielded small (100-300 nm) polyplexes with a positive zeta potential when HMW PEI was used, whereas cross-linked LMW PEI resulted in polyplexes with increased size (>1000 nm) and zeta potentials down to -20 mV. In addition, only cross-linking after polyplex formation was able to enhance resistance against polyanion exchange and high ionic strength. AFM images revealed no changes in the morphology of cross-linked HWM PEI polyplexes, and indentation force measurements using AFM significantly increased mechanical stability of cross-linked HMW PEI polyplexes. These polyplexes also displayed significantly reduced interactions with major blood components like albumin and erythrocytes. The resulting biocompatible particles offer a means of combining enhanced polyplex stability with redox-triggered activation for in vivo application.
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Affiliation(s)
- Michael Neu
- Department of Pharmaceutics and Biopharmacy, Philipps Universität, 35037 Marburg, Germany
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Gómez-Valadés AG, Molas M, Vidal-Alabró A, Bermúdez J, Bartrons R, Perales JC. Copolymers of poly-L-lysine with serine and tryptophan form stable DNA vectors: implications for receptor-mediated gene transfer. J Control Release 2005; 102:277-91. [PMID: 15653152 DOI: 10.1016/j.jconrel.2004.09.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2004] [Accepted: 09/29/2004] [Indexed: 11/22/2022]
Abstract
Inefficient gene transfer and poor stability in physiological medium are important shortcomings for receptor-mediated gene transfer vectors. Here, we evaluate vectors formulated with random copolymers of L-lysine/L-serine (3:1) and L-lysine/L-tryptophan (4:1), focusing on both their biophysical and functional characterization. By means of dynamic light scattering (DLS) and transmission electron microscopy (TEM), we demonstrate that poly-L-lysine (pK), poly-L-lysine-L-tryptophan (pKW) and poly-L-lysine-L-serine (pKS) are able to form compacted, small particles when mixed with plasmid DNA in the absence of salt. Upon dilution in physiological medium, copolymers of both lys/ser and lys/trp do not aggregate, in contrast with poly-L-lysine DNA complexes as determined by scattering, DLS and TEM measurements. Tight packing, as demonstrated by resistance to heparin, SDS and trypsin treatments, is also featured in tryptophan-containing complexes. Successful receptor-mediated endocytosis gene transfer using galactosylated copolymers into cells expressing the asiagloglycoprotein receptor correlated with lack of aggregation. Particles obtained using galactosylated poly-L-lysine-L-tryptophan (Gal-pKW) copolymer demonstrated specific receptor-mediated gene transfer since reporter gene activity dropped in the presence of an excess ligand in the culture medium during transfection. Although copolymers of galactosylated poly-L-lysine-L-serine (Gal-pKS) do not aggregate in the presence of salt, they are not able to internalize in a specific receptor-mediated endocytosis fashion. The introduction of bulky aromatic/hydrophobic (tryptophan) or hydrophillic (serine) moieties into the positively charged vectors allows the compacted particles to disperse into salt-containing medium avoiding salt-induced aggregation. Moreover, tryptophan-containing particles are able to mediate specific gene transfer via receptor-mediated endocytosis.
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Affiliation(s)
- A G Gómez-Valadés
- Unitat de Biofísica, Departament de Ciències Fisiològiques II, IDIBELL-Universitat de Barcelona, Feixa Llarga s/n, 08907 L'Hospitalet, Spain
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One step synthesis and phase transition of phospholipid-modified Au particles into toluene. Colloids Surf A Physicochem Eng Asp 2005. [DOI: 10.1016/j.colsurfa.2004.10.069] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Yu W, Pirollo KF, Yu B, Rait A, Xiang L, Huang W, Zhou Q, Ertem G, Chang EH. Enhanced transfection efficiency of a systemically delivered tumor-targeting immunolipoplex by inclusion of a pH-sensitive histidylated oligolysine peptide. Nucleic Acids Res 2004; 32:e48. [PMID: 15026537 PMCID: PMC390349 DOI: 10.1093/nar/gnh049] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Successful cancer gene therapy depends on the development of non-toxic, efficient, tumor cell- specific systemic gene delivery systems. Our laboratory has developed a systemically administered, ligand-liposome complex that can effectively and preferentially deliver its therapeutic payload to both primary and metastatic tumors. To further improve the transfection efficiency of this targeting complex, a synthetic pH-sensitive histidylated oligolysine K[K(H)KKK]5-K(H)KKC (HoKC), designed to aid in endosomal escape and condensation of DNA, was included in the complex. The presence of HoKC increased the in vitro transfection efficiency over that of the original complex. Moreover, no increase in cytotoxicity was observed due to the presence of the HoKC peptide. In a DU145 human prostate cancer xenograft tumor model in athymic nude mice, inclusion of the HoKC peptide did not interfere with the tumor targeting specificity of the i.v. administered ligand/liposome/DNA complex. Most importantly, the level of transgene expression was significantly elevated in the tumors, but not in the normal tissue in those animals receiving the complex incorporating HoKC. The in vivo enhancement of transfection efficiency by this modified gene delivery vehicle could lead to a reduction in the number of administrations required for antitumor efficacy.
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Affiliation(s)
- Wei Yu
- Department of Oncology, Lombardi Cancer Center, Georgetown University, The Research Building/E420, 3970 Reservoir Road NW, Washington, DC 20057-1469, USA
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Park S, Healy KE. Compositional regulation of poly(lysine-g-(lactide-b-ethylene glycol))–DNA complexation and stability. J Control Release 2004; 95:639-51. [PMID: 15023473 DOI: 10.1016/j.jconrel.2003.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Accepted: 12/03/2003] [Indexed: 11/21/2022]
Abstract
The search for an effective nonviral gene therapy vector has revealed several significant hurdles, such as transient expression and cytotoxicity, that impede the success of these systems. A terpolymer of poly(lysine-g-(lactide-b-ethylene glycol)) [pK-g-p(LL-b-EG)] has been developed, which is capable of stably packaging DNA with significantly less polycation than unmodified polylysine (pK) systems. A comparison of unmodified pK (DP=14, M(w)=2930) to pK grafted with p(LL-b-EG) (M(w tot)=7500) showed that the minimum amine/phosphate ratio (N:P(min)) needed for complete DNA condensation was reduced by 50%. However, when the molecular weight of pK was reduced (DP=4, M(w)=838), there was evidence of terpolymer interference with DNA condensation. Increasing the number of grafted p(LL-b-EG) chains produced a similar result of incomplete DNA condensation. All terpolymer formulations produced complexes with DNA that had greater resistance to salt-induced dissociation and short-term exchange with excess DNA. Terpolymer-DNA complexes exhibited approximately zero-order plasmid release profiles over a period of 6 weeks. The rate of release was dependent on the complex N:P ratio as well as the molecular weights of pLL and pK. The ability to use terpolymer composition to control complex stability and controlled release can provide a means for system optimization for sustained expression profiles of exogenous DNA.
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Affiliation(s)
- Susan Park
- Departments of Bioengineering and Materials Science and Engineering, University of California at Berkeley, 370 Hearst Memorial Mining Building, Berkeley, CA 94720-1760, USA
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Franc BL, Mandl SJ, Siprashvili Z, Wender P, Contag CH. Breaching Biological Barriers: Protein Translocation Domains as Tools for Molecular Imaging and Therapy. Mol Imaging 2003; 2:313-23. [PMID: 14717330 DOI: 10.1162/15353500200303148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The lipid bilayer of a cell presents a significant barrier for the delivery of many molecular imaging reagents into cells at target sites in the body. Protein translocation domains (PTDs) are peptides that breach this barrier. Conjugation of PTDs to imaging agents can be utilized to facilitate the delivery of these agents through the cell wall, and in some cases, into the cell nucleus, and have potential for in vitro and in vivo applications. PTD imaging conjugates have included small molecules, peptides, proteins, DNA, metal chelates, and magnetic nanoparticles. The full potential of the use of PTDs in novel in vivo molecular probes is currently under investigation. Cells have been labeled in culture using magnetic nanoparticles derivatized with a PTD and monitored in vivo to assess trafficking patterns relative to cells expressing a target antigen. In vivo imaging of PTD-mediated gene transfer to cells of the skin has been demonstrated in living animals. Here we review several natural and synthetic PTDs that have evolved in the quest for easier translocation across biological barriers and the application of these peptide domains to in vivo delivery of imaging agents.
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Affiliation(s)
- Benjamin L Franc
- Department of Radiology, Nuclear Medicine Program, University of California, San Francisco 94143-0252, USA.
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Oupický D, Reschel T, Koňák Č, Oupická L. Temperature-Controlled Behavior of Self-Assembly Gene Delivery Vectors Based on Complexes of DNA with Poly(l-lysine)-graft-poly(N-isopropylacrylamide). Macromolecules 2003. [DOI: 10.1021/ma034039a] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Siprashvili Z, Scholl FA, Oliver SF, Adams A, Contag CH, Wender PA, Khavari PA. Gene transfer via reversible plasmid condensation with cysteine-flanked, internally spaced arginine-rich peptides. Hum Gene Ther 2003; 14:1225-33. [PMID: 12952594 DOI: 10.1089/104303403767740768] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nonviral gene transfer offers biosafety, stability, and expense advantages over viruses; however, it has suffered from poor efficiency. Because arginine-rich peptides facilitate uptake of macromolecules such as proteins, liposomes, and iron nanoparticles, we explored their potential in enhancing plasmid DNA delivery. In their unmodified form, known protein transduction sequences, including hepta-arginine and Tat(47-57), failed to support effective gene delivery. However, by flanking a core of consecutive arginines with amino- and carboxy-terminal cysteines in vitro gene transfer was observed. Furthermore, interspersing arginines with glycine and histidine residues achieved reversible plasmid condensation and dramatically increased transfection levels in a variety of cell types. Unlike most available cationic homopolymers that function only in vitro, these new peptides also increased gene expression in both murine and human tissue in vivo. Thus, cysteine-flanked, internally spaced arginine-rich (CFIS-R) peptides represent a new approach to efficient nonviral plasmid delivery using rationally designed protein transduction domains.
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Kwok KY, Park Y, Yang Y, McKenzie DL, Liu Y, Rice KG. In vivo gene transfer using sulfhydryl cross-linked PEG-peptide/glycopeptide DNA co-condensates. J Pharm Sci 2003; 92:1174-85. [PMID: 12761807 DOI: 10.1002/jps.10384] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent interest in sulfhydryl cross-linked nonviral gene delivery systems, designed to trigger the intracellular release of DNA, has inspired studies to establish their utility in vitro. To determine if this concept can be extrapolated to in vivo gene delivery, sulfhydryl cross-linking peptides (dp 20), derivatized with either an N-glycan or polyethylene glycol (PEG), were used to generate sulfhydryl cross-linked gene formulations. The biodistribution, metabolism, cell-type targeting, and gene expression of sulfhydryl cross-linked PEG-peptide/glycopeptide DNA co-condensates were examined following i.v. dosing in mice. Optimal targeting to hepatocytes was achieved by condensing (125)I-DNA with an add-mixture of 10 mol % triantennary glycopeptide, 5 mol % PEG-peptide, and 85 mol % backbone peptide. Four backbone peptides were substituted into the formulation to examine the influence of peptide metabolism and disulfide bond strength on the rate of DNA metabolism and the level of gene expression in vivo. The half-life of DNA in liver was extended from 1 to 3 h using a backbone peptide composed of d-amino acids, whereas substituting penicillamine for cysteine failed to further increase the metabolic stability of DNA. Optimized gene delivery formulations transiently expressed secreted alkaline phosphatase in mouse serum for 12 days. The results suggest that disulfide bond reduction in liver hepatocytes proceeds rapidly, followed by peptide metabolism, ultimately limiting the metabolic half-life of sulfhydryl cross-linked DNA condensates in vivo.
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Affiliation(s)
- Kai Y Kwok
- Department of Pharmaceutics and Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109-1065, USA
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Abstract
The use of various synthetic lipids and polymers to deliver DNA for gene therapy applications has been the subject of intense examination for the last 15 years. Our understanding of the processes involved in the delivery of DNA, although still limited, can be described in terms of specific physical and chemical barriers encountered along the delivery pathway. Successful engagement of this pathway involves avoiding inactivation in the extracellular compartment and initial favorable interactions with the cell surface. Internalization of the delivery system by endocytosis results in a poorly defined endosomal trafficking process which, if not escaped, leads to degradation of the therapeutic DNA in lysosomes. For the small fraction of material that is able to escape this vesicular trafficking pathway, the cytosol provides additional physical and metabolic barriers to further trafficking to the nucleus. Finally, nuclear uptake has been demonstrated to be a significant barrier to gene delivery. In this review, we outline in greater detail the various processes involved in each step and describe various formulation variables that have been explored to overcome these delivery barriers to nonviral gene delivery.
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Affiliation(s)
- Christopher M Wiethoff
- Department of Pharmaceutical Chemistry, The University of Kansas, 2095 Constant Avenue, Lawrence, Kansas 66047, USA
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Abstract
The success of gene therapy is largely dependent on the development of the gene delivery vector. Recently, gene transfection into target cells using naked DNA, which is a simple and safe approach, has been improved by combining several physical techniques, for example, electroporation, gene gun, ultrasound and hydrodynamic pressure. Chemical approaches have been utilized to improve the efficiency and cell specificity of gene transfer. Novel gene carrier molecules, which facilitate DNA escape from the endosome into the cytosol, have been developed. Several functional polymers, which enable controlled release of DNA in response to an environmental change, have also been reported. Plasmids with reduced number of CpG motifs, the use of PCR fragments and the sequential injection method have been established for the reduction of immune response triggered by plasmid DNA. Construction of a long-lasting gene expression system is also an important theme for nonviral gene therapy. To date, tissue-specific expression, self-replicating and integrating plasmid systems have been reported. Improvement of delivery methods together with intelligent design of the DNA itself has brought about large degrees of enhancement in the efficiency, specificity and temporal control of nonviral vectors.
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Affiliation(s)
- T Niidome
- Center for Pharmacogenetics, School of Pharmacy, 633 Salk Hall, University of Pittsburgh, Pittsburgh, PA 15213, USA
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