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Abesekara MS, Chau Y. Recent advances in surface modification of micro- and nano-scale biomaterials with biological membranes and biomolecules. Front Bioeng Biotechnol 2022; 10:972790. [PMID: 36312538 PMCID: PMC9597319 DOI: 10.3389/fbioe.2022.972790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 09/26/2022] [Indexed: 11/16/2022] Open
Abstract
Surface modification of biomaterial can improve its biocompatibility and add new biofunctions, such as targeting specific tissues, communication with cells, and modulation of intracellular trafficking. Here, we summarize the use of various natural materials, namely, cell membrane, exosomes, proteins, peptides, lipids, fatty acids, and polysaccharides as coating materials on micron- and nano-sized particles and droplets with the functions imparted by coating with different materials. We discuss the applicability, operational parameters, and limitation of different coating techniques, from the more conventional approaches such as extrusion and sonication to the latest innovation seen on the microfluidics platform. Methods commonly used in the field to examine the coating, including its composition, physical dimension, stability, fluidity, permeability, and biological functions, are reviewed.
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Shinohara F, Oashi T, Harumoto T, Nishikawa T, Takayama Y, Miyagi H, Takahashi Y, Nakajima T, Sawada T, Koda Y, Makino A, Sato A, Hamaguchi K, Suzuki M, Yamamoto J, Tomari Y, Saito JI. siRNA potency enhancement via chemical modifications of nucleotide bases at the 5'-end of the siRNA guide strand. RNA (NEW YORK, N.Y.) 2021; 27:163-173. [PMID: 33177188 PMCID: PMC7812868 DOI: 10.1261/rna.073783.119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 11/05/2020] [Indexed: 05/03/2023]
Abstract
Small interfering RNAs (siRNAs) can be utilized not only as functional biological research tools but also as therapeutic agents. For the clinical use of siRNA as drugs, various chemical modifications have been used to improve the activity of siRNA drugs, and further chemical modifications are expected to improve the utility of siRNA therapeutics. As the 5' nucleobase of the guide strand affects the interaction between an siRNA and AGO2 and target cleavage activity, structural optimization of this specific position may be a useful strategy for improving siRNA activity. Here, using the in silico model of the complex between human AGO2 MID domain and nucleoside monophosphates, we screened and synthesized an original adenine-derived analog, 6-(3-(2-carboxyethyl)phenyl)purine (6-mCEPh-purine), that fits better than the natural nucleotide bases into the MID domain of AGO2. Introduction of the 6-mCEPh-purine analog at the 5'-end of the siRNA guide strand significantly enhanced target knockdown activity in both cultured cell lines and in vivo animal models. Our findings can help expand strategies for rationally optimizing siRNA activity via chemical modifications of nucleotide bases.
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Affiliation(s)
- Fumikazu Shinohara
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
- Laboratory of RNA Function, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Taiji Oashi
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Toshimasa Harumoto
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Tomoyuki Nishikawa
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Yuki Takayama
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Hikaru Miyagi
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Yuichi Takahashi
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Takahiro Nakajima
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Takashi Sawada
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Yasuo Koda
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Asana Makino
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Atsuko Sato
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Kaori Hamaguchi
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Michihiko Suzuki
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Junichiro Yamamoto
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
| | - Yukihide Tomari
- Laboratory of RNA Function, Institute for Quantitative Biosciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Jun-Ichi Saito
- Research Function Unit, R&D Division, Kyowa Kirin Co. Ltd., Chiyoda-ku, Tokyo 100-0004, Japan
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Mukai H, Hatanaka K, Yagi N, Warashina S, Zouda M, Takahashi M, Narushima K, Yabuuchi H, Iwano J, Kuboyama T, Enokizono J, Wada Y, Watanabe Y. Pharmacokinetic evaluation of liposomal nanoparticle-encapsulated nucleic acid drug: A combined study of dynamic PET imaging and LC/MS/MS analysis. J Control Release 2018; 294:185-194. [PMID: 30529725 DOI: 10.1016/j.jconrel.2018.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 12/04/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022]
Abstract
In vivo biodistribution analyses, especially in tumors, of nucleic acids delivered with nanoparticles are important to develop drug delivery technologies for medical use. We previously developed wrapsome® (WS), an ~100 nm liposomal nanoparticle that can encapsulate siRNA, and reported that WS accumulates in tumors in vivo and inhibits their growth by an enhanced permeability and retention effect. In the present study, we evaluated the pharmacokinetics of nucleic acid-containing nanoparticles by combining dynamic positron emission tomography (PET) imaging and liquid chromatography-tandem mass spectrometry (LC/MS/MS) analysis. An 18-mer phosphorothioate oligodeoxynucleotide (ODN), trabedersen, was used as a model drug and was encapsulated in WS. Dynamic PET imaging and time-activity curve analysis of WS-encapsulated 64Cu-labeled ODNs administered to mice with MIA PaCa-2 subcutaneous xenograft tumors showed tumor accumulation (~3% injected dose per gram (%ID/g)) and liver accumulation (~30 %ID/g) at 24 h. Under these conditions, LC/MS/MS analysis showed that the level of intact ODNs was 1.62 %ID/g in the tumor and 1.70 %ID/g in the liver. From these pharmacokinetic data, the intact/accumulated ODN ratios were calculated using the following equation: intact/accumulated ODN ratio (%) = %ID/g LC/MS/MS, tissue, mean/%ID/g PET, tissue, mean × 100. Interestingly, the ratios for the tumor and kidney were maintained at 20-50% over 48 h after administration of the WS-encapsulated form. In contrast, the ratio for the liver rapidly decreased at 24 h, showing the same pattern as that for naked ODN. These different patterns indicate that WS effectively protected the ODN in the tumor and kidney, but protected it less efficiently in the liver. A combined approach of dynamic PET imaging and LC/MS/MS analysis will assist the development of nanoparticle-encapsulated nucleic acid drugs, such as those using WSs, to determine their detailed pharmacokinetics.
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Affiliation(s)
- Hidefumi Mukai
- Molecular Network Control Imaging Unit, Molecular Network Control Research Project, Center Director's Strategic Program, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
| | - Kentaro Hatanaka
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan
| | - Nobuhiro Yagi
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan
| | - Shota Warashina
- Molecular Network Control Imaging Unit, Molecular Network Control Research Project, Center Director's Strategic Program, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Maki Zouda
- Molecular Network Control Imaging Unit, Molecular Network Control Research Project, Center Director's Strategic Program, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Maiko Takahashi
- Molecular Network Control Imaging Unit, Molecular Network Control Research Project, Center Director's Strategic Program, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Laboratory for Molecular Delivery and Imaging Technology, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Kazuya Narushima
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan
| | - Hayato Yabuuchi
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan
| | - Junko Iwano
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan
| | - Takeshi Kuboyama
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan.
| | - Junichi Enokizono
- Research Core Function Laboratories, Research Function Unit, R&D Division, Kyowa Hakko Kirin Co., Ltd., 3-6-6, Asahi-machi, Machida-shi, Tokyo 194-8533, Japan
| | - Yasuhiro Wada
- Pathophysiological and Health Science Team, Imaging Platform and Innovation Group, Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Laboratory for Pathophysiological and Health Science, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan
| | - Yasuyoshi Watanabe
- Pathophysiological and Health Science Team, Imaging Platform and Innovation Group, Division of Bio-Function Dynamics Imaging, RIKEN Center for Life Science Technologies, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Laboratory for Pathophysiological and Health Science, RIKEN Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
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Abe Y, Sakai-Kato K, Goda Y. Cell Type-Specific Responses of Peripheral Blood CD14-Positive Monocytes to Liposome-Encapsulated Immunostimulatory siRNA. Biol Pharm Bull 2016; 39:1859-1867. [DOI: 10.1248/bpb.b16-00450] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Yasuhiro Abe
- Division of Drugs, National Institute of Health Sciences
| | | | - Yukihiro Goda
- Division of Drugs, National Institute of Health Sciences
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Mannosylated chitosan nanoparticles for delivery of antisense oligonucleotides for macrophage targeting. BIOMED RESEARCH INTERNATIONAL 2014; 2014:526391. [PMID: 25057492 PMCID: PMC4098891 DOI: 10.1155/2014/526391] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/02/2014] [Indexed: 12/11/2022]
Abstract
The therapeutic potential of antisense oligonucleotides (ASODN) is primarily dependent upon its safe and efficient delivery to specific cells overcoming degradation and maximizing cellular uptake in vivo. The present study focuses on designing mannosylated low molecular weight (LMW) chitosan nanoconstructs for safe ODNs delivery by macrophage targeting. Mannose groups were coupled with LMW chitosan and characterized spectroscopically. Mannosylated chitosan ODN nanoparticles (MCHODN NPs) were formulated by self-assembled method using various N/P ratio (moles of amine groups of MCH to phosphate moieties of ODNs) and characterized for gel retardation assay, physicochemical characteristics, cytotoxicity and transfection efficiency, and antisense assay. Complete complexation of MCH/ODN was achieved at charge ratio of 1:1 and above. On increasing the N/P ratio of MCH/ODN, particle size of the NPs decreased whereas zeta potential (ZV) increased. MCHODN NPs displayed much higher transfection efficiency into Raw 264.7 cells (bears mannose receptors) than Hela cells and no significant toxicity was observed at all MCH concentrations. Antisense assay revealed that reduction in lipopolysaccharide (LPS) induced serum TNF-α is due to antisense activity of TJU-2755 ODN (sequence complementary to 3′-UTR of TNF-α). These results suggest that MCHODN NPs are acceptable choice to improve transfection efficiency in vitro and in vivo.
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A novel nonviral gene delivery system: multifunctional envelope-type nano device. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2014; 119:197-230. [PMID: 19343308 DOI: 10.1007/10_2008_40] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
In this review we introduce a new concept for developing a nonviral gene delivery system which we call "Programmed Packaging." Based on this concept, we succeeded in developing a multifunctional envelope-type nano device (MEND), which exerts high transfection activities equivalent to those of an adenovirus in a dividing cell. The use of MEND has been extended to in vivo applications. PEG/peptide/DOPE ternary conjugate (PPD)-MEND, a new in vivo gene delivery system for the targeting of tumor cells that dissociates surface-modified PEG in tumor tissue by matrix metalloproteinase (MMP) and exerts significant transfection activities, was developed. In parallel with the development of MEND, a quantitative gene delivery system, Confocal Image-assisted 3-dimensionally integrated quantification (CIDIQ), also was developed. This method identified the rate-limiting step of the nonviral gene delivery system by comparing it with adenoviral-mediated gene delivery. The results of this analysis provide a new direction for the development of rational nonviral gene delivery systems.
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Tavakoli S, Tamaddon AM, Golkar N, Samani SM. Microencapsulation of (deoxythymidine)₂₀-DOTAP complexes in stealth liposomes optimized by Taguchi design. J Liposome Res 2014; 25:67-77. [PMID: 24960449 DOI: 10.3109/08982104.2014.928889] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Stealth liposomes encapsulating oligonucleotides are considered as promising non-viral gene delivery carriers; however, general preparation procedures are not capable to encapsulate nucleic acids (NAs) efficiently. In this study, the lyophobic complexes of deoxythymidine20 oligonucleotide (dT20) and DOTAP were used instead of free dT20 for nano-encapsulation process by reverse phase evaporation method. Regarding the various factors that can potentially affect the liposome characteristics, Taguchi design was applied to analyze the simultaneous effects of factors comprising PEG-lipid (%), dT20/total lipid molar ratio, cholesterol (Chol%) and organic-to-aqueous phase ratio (o/w) at three levels. The response variables, hydrodynamic diameter, loading efficiency (LE%) and capacity (LC%), were studied by dynamic light scattering and ethidium bromide exclusion assay, respectively. The optimum condition described by minimum particle size as well as high LE% and LC% was obtained at 5% PEG-lipid, dT20/total lipid of 7, 20% Chol and o/w of 3 with an average size of 84 nm, LE% = 83.4% and LC% = 11.6%. Moreover, stability assessments in presence of heparin sulfate revealed the noticeable resistance, unlike DOTAP/dT20 lipoplexes, to premature release of NA. Transmission electron microscopy confirmed formation of discrete and circular vesicles encapsulating dT20.
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Tagami T, Uehara Y, Moriyoshi N, Ishida T, Kiwada H. Anti-PEG IgM production by siRNA encapsulated in a PEGylated lipid nanocarrier is dependent on the sequence of the siRNA. J Control Release 2011; 151:149-54. [DOI: 10.1016/j.jconrel.2010.12.013] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 12/06/2010] [Accepted: 12/24/2010] [Indexed: 11/28/2022]
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Zhao X, Pan F, Holt CM, Lewis AL, Lu JR. Controlled delivery of antisense oligonucleotides: a brief review of current strategies. Expert Opin Drug Deliv 2009; 6:673-86. [PMID: 19552611 DOI: 10.1517/17425240902992894] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Antisense therapy has been investigated extensively over the past two decades, either experimentally for gene functional research or clinically as therapeutic agents owing to the conceptual simplicity, ease of design and low cost. The concept of this therapeutic approach is promising because short antisense oligonucleotides (ASOs) can be delivered into target cells for specific hybridisation with target mRNA, resulting in the inhibition of the expression of pathogenic genes. However, the efficient delivery of the ASO molecules into target cells remains challenging; this bottleneck together with several other technical hurdles need to be overcome before this approach becomes effective and widely adopted. A variety of vectors such as lipids, polymers, peptides and nanoparticles have been explored. This review outlines the recent advances of the non-viral ASO delivery strategies. Several recent scientific studies, including authors' contributions, have been selected to highlight the technical aspects of ASO delivery.
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Affiliation(s)
- Xiubo Zhao
- University of Manchester, School of Physics and Astronomy, Biological Physics Group, Schuster Building, Manchester M13 9PL, UK.
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Yagi N, Manabe I, Tottori T, Ishihara A, Ogata F, Kim JH, Nishimura S, Fujiu K, Oishi Y, Itaka K, Kato Y, Yamauchi M, Nagai R. A nanoparticle system specifically designed to deliver short interfering RNA inhibits tumor growth in vivo. Cancer Res 2009; 69:6531-8. [PMID: 19654315 DOI: 10.1158/0008-5472.can-08-3945] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Use of short interfering RNA (siRNA) is a promising new approach thought to have a strong potential to lead to rapid development of gene-oriented therapies. Here, we describe a newly developed, systemically injectable siRNA vehicle, the "wrapsome" (WS), which contains siRNA and a cationic lipofection complex in a core that is fully enveloped by a neutral lipid bilayer and hydrophilic polymers. WS protected siRNA from enzymatic digestion, providing a long half-life in the systemic circulation. Moreover, siRNA/WS leaked from blood vessels within tumors into the tumor tissue, where it accumulated and was subsequently transfected into the tumor cells. Because the transcription factor KLF5 is known to play a role in tumor angiogenesis, we designed KLF5-siRNA to test the antitumor activity of siRNA/WS. KLF5-siRNA/WS exhibited significant antitumor activity, although neither WS containing control scrambled-siRNA nor saline containing KLF5-siRNA affected tumor growth. KLF5-siRNA/WS inhibited Klf5 expression within tumors at both mRNA and protein levels, significantly reducing angiogenesis, and we detected no significant acute or long-term toxicity. Our findings support the idea that siRNA/WS can be used to knock down specific genes within tumors and thereby exert therapeutic effects against cancers.
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Affiliation(s)
- Nobuhiro Yagi
- Department of Cardiovascular Medicine, University of Tokyo Graduate School of Medicine, Japan
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Sonoke S, Ueda T, Fujiwara K, Sato Y, Takagaki K, Hirabayashi K, Ohgi T, Yano J. Tumor regression in mice by delivery of Bcl-2 small interfering RNA with pegylated cationic liposomes. Cancer Res 2008; 68:8843-51. [PMID: 18974128 DOI: 10.1158/0008-5472.can-08-0127] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The pharmacokinetics and antitumor activity of pegylated small interfering RNA (siRNA)/cationic liposome complexes were studied after systemic administration to mice. We designed pegylated-lipid carriers for achieving increased plasma concentrations of RNA and hence improved accumulation of RNA in tumors by the enhanced permeability and retention effect. We compared the pharmacokinetics of siRNA complexed with liposomes incorporating pegylated lipids with longer (C-17 or C-18), shorter (C-12 to C-16), or unsaturated (C-18:1) acyl chains. When longer acyl chains were used, the plasma concentrations of siRNA obtained were dramatically higher than when shorter or unsaturated chains were used. This may be explained by the higher gel-to-liquid-crystalline phase-transition temperature (Tc) of lipids with longer acyl chains, which may form more rigid liposomes with reduced uptake by the liver. We tested a siRNA that is sequence specific for the antiapoptotic bcl-2 mRNA complexed with a pegylated liposome incorporating a C-18 lipid (PEG-LIC) by i.v. administration in a mouse model of human prostate cancer. Three-fold higher accumulation of RNA in the tumors was achieved when PEG-LIC rather than nonpegylated liposomes was used, and sequence-specific antitumor activity was observed. Our siRNA/PEG-LIC complex showed no side effects on repeated administration and the strength of its antitumor activity may be attributed to its high uptake by the tumors. Pegylation of liposomes improved the plasma retention, uptake by s.c. tumors, and antitumor activity of the encapsulated siRNA. PEG-LIC is a promising candidate for siRNA cancer therapy.
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Affiliation(s)
- Satoru Sonoke
- Discovery Research Laboratories, Nippon Shinyaku Co Ltd, Tsukuba, Japan.
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