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Gaurav I, Thakur A, Iyaswamy A, Wang X, Chen X, Yang Z. Factors Affecting Extracellular Vesicles Based Drug Delivery Systems. Molecules 2021; 26:molecules26061544. [PMID: 33799765 PMCID: PMC7999478 DOI: 10.3390/molecules26061544] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 02/18/2021] [Accepted: 02/19/2021] [Indexed: 02/07/2023] Open
Abstract
Extracellular vesicles (EVs) play major roles in intracellular communication and participate in several biological functions in both normal and pathological conditions. Surface modification of EVs via various ligands, such as proteins, peptides, or aptamers, offers great potential as a means to achieve targeted delivery of therapeutic cargo, i.e., in drug delivery systems (DDS). This review summarizes recent studies pertaining to the development of EV-based DDS and its advantages compared to conventional nano drug delivery systems (NDDS). First, we compare liposomes and exosomes in terms of their distinct benefits in DDS. Second, we analyze what to consider for achieving better isolation, yield, and characterization of EVs for DDS. Third, we summarize different methods for the modification of surface of EVs, followed by discussion about different origins of EVs and their role in developing DDS. Next, several major methods for encapsulating therapeutic cargos in EVs have been summarized. Finally, we discuss key challenges and pose important open questions which warrant further investigation to develop more effective EV-based DDS.
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Affiliation(s)
- Isha Gaurav
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China; (I.G.); (A.I.); (X.W.); (X.C.)
| | - Abhimanyu Thakur
- Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation-CAS Limited, Hong Kong, China;
| | - Ashok Iyaswamy
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China; (I.G.); (A.I.); (X.W.); (X.C.)
- Mr. & Mrs. Ko Chi-Ming Centre for Parkinson’s Disease Research, School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China
| | - Xuehan Wang
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China; (I.G.); (A.I.); (X.W.); (X.C.)
| | - Xiaoyu Chen
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China; (I.G.); (A.I.); (X.W.); (X.C.)
| | - Zhijun Yang
- School of Chinese Medicine, Hong Kong Baptist University, Hong Kong, China; (I.G.); (A.I.); (X.W.); (X.C.)
- Changshu Research Institute, Hong Kong Baptist University, Changshu Economic and Technological Development (CETD) Zone, Changshu 215500, Jiangsu Province, China
- Correspondence: ; Tel.: +852-3411-2961
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Abstract
Model phospholipid liposomes have been utilized widely to study the molecular interactions between peptides and membrane bilayers. In the mechanistic study of Alzheimer's disease (AD), disruption of neuronal cell membranes has been considered as a major contribution for the β-amyloid (Aβ) peptides' neurotoxicity. However, clear interpretation of the Aβ-induced cellular membrane at high-resolution level is challenging because of the co-existence of multiple pathways. Here we present the generation of simplified model liposome systems that will facilitate the in-depth mechanistic studies. Protocols for the preparation of model liposomes and the characterization of individual membrane disruption effects will be described.
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Affiliation(s)
- Wei Qiang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, USA.
| | - Katelynne E Doherty
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY, USA
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3
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Hernandez JM. Reconstitution of Synaptic SNAREs into Large Liposomes with Reduced Curvature Stress. Methods Mol Biol 2017; 1538:93-105. [PMID: 27943186 DOI: 10.1007/978-1-4939-6688-2_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Liposomes constitute a convenient biochemical model system to investigate mechanistic aspects of the membrane fusion of synaptic vesicles. The proteins responsible for mediating fusion are the SNAREs that belong to a highly conserved family of transmembrane proteins. Reconstituting SNAREs into liposomes using detergents has become a common approach not only to understand how SNAREs work, but also how fusion is regulated by the vast array of accessory proteins present at the presynapse. However, a concern has been that the high curvature stress of the small liposomes (diameters of ~40 nm) frequently used in many studies renders them prone to spontaneous fusion, bringing into question whether the measurements obtained faithfully represent SNARE-mediated fusion. By systematically varying the detergent concentration and characterizing the SNARE-liposome size distributions by light scattering, we describe a detailed procedure to reconstitute SNAREs into large liposomes with considerably reduced curvature stress.
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Affiliation(s)
- Javier M Hernandez
- Department of Structural Biochemistry, Max Planck Institute for Molecular Physiology, Otto-Hahn-Str. 11, 44202, Dortmund, Germany.
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Sun Q, Chen X, Yu J, Zen K, Zhang CY, Li L. Immune modulatory function of abundant immune-related microRNAs in microvesicles from bovine colostrum. Protein Cell 2013; 4:197-210. [PMID: 23483481 DOI: 10.1007/s13238-013-2119-9] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 12/19/2012] [Indexed: 11/25/2022] Open
Abstract
Colostrum provides essential nutrients and immunologically active factors that are beneficial to newborns. Our previous work demonstrated that milk contains large amounts of miRNA that is largely stored in milk-derived microvesicles (MVs). In the present study, we found that the MVs from colostrum contain significantly higher levels of several immune-related miRNAs. We hypothesized that the colostrum MVs may transfer the immune-related miRNAs into cells, which contribute to its immune modulatory feature. We isolated colostrum MVs by ultracentrifugation and demonstrated several immune modulation features associated with miRNAs. We also provide evidence that the physical structure of milk-derived MVs is essential for transfer miRNAs and following immune modulation effect. Moreover, we found that colostrum powder-derived MVs also contains higher levels of immune-related miRNAs that display similar immune modulation effects. Taken together, these results show that MV-containing immunerelated miRNAs may be a novel mechanism by which colostrum modulates body immune response.
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Affiliation(s)
- Qi Sun
- Jiangsu Engineering Research Center for microRNA Biology and Biotechnology, State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University School of Life Sciences, Nanjing, 210093, China
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Kim TH, Yu GS, Choi H, Shim YJ, Lee M, Choi JS. Preparation of dexamethasone-based cationic liposome and its application to gene delivery in vitro. J Nanosci Nanotechnol 2011; 11:1799-1802. [PMID: 21456295 DOI: 10.1166/jnn.2011.3407] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this study, dexamethasone was conjugated to PAMAM dendrimer (generation 0) and its gene transfection efficiency was investigated. To make a liposomal solution for gene delivery, DOPE was used as a fusogenic helper lipid. In gel retardation assay, PAMAM-dexamethasone conjugate (PAM-Dex)/DOPE liposome/DNA complex was completely retarded at 8:1 N/P (nitrogen/phosphate) ratio. The physicochemical characteristics are studied by measuring the average size distribution and zeta-potential values of the complexes. In vitro transfection assay showed that the PAM-Dex/DOPE liposome/DNA complex displayed higher gene delivery efficiency compared to PAMAM/DNA complex. In addition, PAM-Dex/DOPE liposome showed the lowest toxicity compared to PAMAM, PEI 25 kD and Lipofectamine. These results indicate that PAM-Dex/DOPE liposome has a potential to be used as an efficient gene carrier for gene therapy.
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Affiliation(s)
- Tae-Hun Kim
- Department of Biochemistry, Chungnam National University, Daejeon 305-764, Korea
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Abstract
Immunoliposomes generated by coupling of antibodies to the liposomal surface allow for an active tissue targeting, e.g., through binding to tumor cell-specific receptors. Instead of whole antibodies, single-chain Fv fragments (scFv), which represent the smallest part of an antibody containing the entire antigen-binding site, find increasing usage as targeting moiety. Here we provide protocols for the preparation of type II scFv immunoliposomes by the conventional coupling method as well as the post-insertion method. Furthermore protocols to analyze binding of these immunoliposomes to antigen-expressing cells as well as internalization through receptor-mediated endocytosis are included.
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Affiliation(s)
- Miriam Rothdiener
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
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Cheng Z, Zhou H, Luther M, Yin JJ, Yu LL. Effects of wheat antioxidants on oxygen diffusion-concentration products in liposomes and mRNA levels of HMG-CoA reductase and cholesterol 7alpha-hydroxylase in primary rat hepatocytes. J Agric Food Chem 2008; 56:5033-5042. [PMID: 18540627 DOI: 10.1021/jf800308n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Three wheat antioxidant fractions were investigated for their potential effects on oxygen diffusion-concentration products in liposomes prepared with egg yolk phosphatidycholine (yolk PC) and rat liver PC (liver PC), using the electron spin resonance (ESR) oximetry method with 2,2'-azobis(2-aminopropane) dihydrochloride (AAPH) and 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) as radical generators. Both water-soluble wheat antioxidant (WWA) and the second lipophilic antioxidant (LWA2) fractions were able to inhibit oxygen diffusion-concentration product induced by either AAPH or AMVN. The first lipophilic wheat antioxidant (LWA1) fraction only showed antioxidant activity in yolk PC liposomes with AAPH as the radical initiator but had pro-oxidant activity under other testing conditions. Both liposome composition and radical initiator altered the antioxidative properties of WWA, LWA1, and LWA2. WWA also showed the strongest DPPH(*) scavenging capacity on a per grain weight basis. HPLC analysis showed that WWA had a much higher level of total phenolic acids, which may partially explain their antioxidant properties. In addition, wheat antioxidants significantly down-regulated the mRNA of HMG-CoA reductase, the key enzyme for cholesterol biosynthesis, and up-regulated the mRNA of cholesterol 7alpha-hydroxylase (CYP7A1), the key enzyme for cholesterol metabolism, in primary rat hepatocytes. These data indicated the potential of wheat antioxidants in reducing the risk of atherosclerosis through multimechanisms.
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Affiliation(s)
- Zhihong Cheng
- Department of Nutrition and Food Science, University of Maryland, College Park, Maryland 20742, USA
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Abstract
Lipid-mixing assay is now commonly used to study protein, temperature and ion-dependent membrane fusion events. This assay has been crucial to demonstrate the ability of neuronal and non-neuronal soluble NSF attachment receptor (SNARE) to promote spontaneous fusion of liposomes. This lipid-mixing assay is based on the fluorescence resonance energy transfer (FRET) capability between a donor fluorescent lipid and a quenching lipid. When fusion between donor fluorescent liposomes and nonfluorescent acceptor liposome occurred, FRET decreases. This assay allows a real-time reading of SNARE-mediated liposome fusion.
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Affiliation(s)
- Jérôme Vicogne
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY, USA
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Sabaté R, Barnadas-Rodríguez R, Callejas-Fernández J, Hidalgo-Alvarez R, Estelrich J. Preparation and characterization of extruded magnetoliposomes. Int J Pharm 2007; 347:156-62. [PMID: 17692483 DOI: 10.1016/j.ijpharm.2007.06.047] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2006] [Revised: 06/21/2007] [Accepted: 06/27/2007] [Indexed: 11/24/2022]
Abstract
Phospholipid vesicles encapsulating magnetic nanoparticles (here after called magnetoliposomes) have been prepared for targeting a drug to a specific organ using a magnetic force, as well as for local hyperthermia therapy. Magnetoliposomes are also an ideal platform for use as contrast agents. We describe the preparation and characterization of liposomes containing magnetite, a ferrimagnetic material. These liposomes were obtained by extrusion. To prevent the aggregation of particles, the magnetite was treated--prior to encapsulation--with a surfactant, resulting in a stable ferrofluid suspension. Once the ferrofluid had been obtained, it was used to hydrate the phospholipid layers. Magnetoliposomes had a diameter of around 200 nm, the same pore size as the membranes used for the extrusion. The encapsulation efficiency was dependent on the initial amount of ferrofluid present at the encapsulation stage, and in the worst case was 19%. This value corresponded to 82.06 mmol of magnetite per mole of phospholipid. Although we have used a determined membrane pore to obtain the magnetoliposomes, the method described here allows to prepare magnetoliposomes of different sizes as well as of different magnetite content.
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Affiliation(s)
- Raimon Sabaté
- Departament de Fisicoquímica, Facultat de Farmàcia, Universitat de Barcelona, Avda. Joan XXIII, s/n, 08028-Barcelona, Catalonia, Spain
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Abstract
We report a new type of gel-liquid phase segregation in giant unilamellar vesicles (GUVs) of mixed lipids. Coexisting patch- and stripe-shaped gel domains in GUV bilayers composed of DOPC/DPPC or DLPC/DPPC are observed by confocal fluorescence microscopy. The lipids in stripe domains are shown to be tilted according to the DiIC18 fluorescence intensity dependence on the excitation polarization. The patch domains are found to be mainly composed of DPPC-d62 according to the coherent anti-Stokes Raman scattering (CARS) images of DOPC/DPPC-d62 bilayers. When cooling GUVs from above the miscibility temperature, the patch domains start to appear between the chain melting and the pretransition temperature of DPPC. In GUVs containing a high molar percentage of DPPC, the stripe domains form below the pretransition temperature. Our observations suggest that the patch and stripe domains are in the Pbeta' and Lbeta' gel phases, respectively. According to the thermoelastic properties of GUVs described by Needham and Evans [(1988) Biochemistry 27, 8261-8269], the Pbeta' and Lbeta' phases are formed at relatively low and high membrane tensions, respectively. GUVs with high DPPC percentage have high membrane surface tension and thus mainly exhibit Lbeta' domains, while GUVs with low DPPC percentage have low membrane surface tension and form Pbeta' domains accordingly. Adding negatively charged lipid to the lipid mixtures or applying an osmotic pressure to GUVs using sucrose solutions releases the surface tension and leads to the disappearance of the Lbeta' gel phase. The relationship between the observed domains in free-standing GUV bilayers and those in supported bilayers is discussed.
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Affiliation(s)
- Li Li
- Weldon School of Biomedical Engineering and Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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12
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Abstract
CE enabled assessing the attachment of hexa-histidine-tagged proteins to functionalized phospholipid liposomes. The liposomes were made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, phosphatidyl-ethanolamine, cholesterol and distearoyl-glycero-3-phosphoethanolamine-N-methoxy(polyethylene glycol) in a molar ratio of 29:26:40:5. The unilamellar vesicles, which had an average diameter of 170 nm, were labelled by inclusion of FITC-dextran for fluorescence detection. CE was carried out in poly(vinyl alcohol) (PVA)-coated capillaries at 25 degrees C with a BGE consisting of Tris-HCl (50 mM, pH 8.0). For conjugation of the liposomes with the proteins (soluble synthetic receptor fragments with molecular mass of 60 and 70 kDa, respectively), Ni(2+) was implanted into the vesicle surface by an anchor lipid containing a nitrilotriacetate acid (NTA) group as complexation agent for the metal ions. The difference in surface charge enabled the separation of the different species of interest by CE: plain vesicles, vesicles functionalised with Ni-NTA, vesicle-protein complexes and the species formed upon removal of the Ni-ions by complexation with EDTA. Loss of the Ni-ions resulted in the release of the proteins and the reappearance of the plain Ni-free NTA-liposome species in the electropherograms.
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Affiliation(s)
- Gerhard Bilek
- Institute for Analytical Chemistry, University of Vienna, Vienna, Austria
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Otake K, Shimomura T, Goto T, Imura T, Furuya T, Yoda S, Takebayashi Y, Sakai H, Abe M. One-step preparation of chitosan-coated cationic liposomes by an improved supercritical reverse-phase evaporation method. Langmuir 2006; 22:4054-9. [PMID: 16618144 DOI: 10.1021/la051662a] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
High-pressure carbon dioxide in contact with water dissolves to form carbonic acid, causing a decrease in pH. By use of these characteristics of a CO2/H2O biphasic system, chitosan-coated cationic liposomes of l-alpha-dipalmitoylphosphatidylcholine were successfully prepared by an improved supercritical reverse-phase evaporation (ISCRPE) method. Liposome-chitosan complexes carrying a positive charge were prepared in a single-step procedure without the use of acid or organic solvent, including ethanol. The maximum trapping efficiency of liposomes prepared by the ISCRPE method was 17%, with or without the addition of chitosan, compared to only 2% for liposomes prepared by the Bangham method. Furthermore, the liposomal dispersion was stable at room temperature in a sealed tube for over 30 days.
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Affiliation(s)
- Katsuto Otake
- Nanotechnology Research Institute and Research Institute for Innovation in Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8565, Japan.
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Wang T, Deng Y, Geng Y, Gao Z, Zou J, Wang Z. Preparation of submicron unilamellar liposomes by freeze-drying double emulsions. Biochim Biophys Acta 2006; 1758:222-31. [PMID: 16563340 DOI: 10.1016/j.bbamem.2006.01.023] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2005] [Revised: 01/23/2006] [Accepted: 01/23/2006] [Indexed: 11/20/2022]
Abstract
A novel method is described for the preparation of sterile submicron unilamellar liposomes. The method is based on the lyophilization of double emulsions containing disaccharides as lyoprotectants in both the inner and outer aqueous phase. Using various phospholipids or mixtures of lipids as emulsifiers, the double emulsions can be prepared by a two-step emulsification, including hydrophilic agents in the inner aqueous phase or lipophilic agents in the oil phase. Then, the double emulsions are lyophilized after sterilization by passing them through a 0.22-microm pore filter. Rehydration of the lyophilized products results in liposomes with a relatively high encapsulation efficiency (for calcein, 87%; 5-fluorouracil, 19%; flurbiprofen, 93%) and a size below 200 nm measured by the dynamic light scattering technique (DLS) and the atomic force microscopy (AFM). The liposomes were found to be unilamellar from freeze-fracture electron micrographs and X-ray diffraction patterns. In addition, the liposomes can be reconstituted just before use by rehydration of the lyophilized products which are relatively stable. Thus, this reproducible and simple technique can be used to prepare sterilized, submicron unilamellar liposomes with a relatively high encapsulation efficiency, and excellent stability during long-term storage.
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Affiliation(s)
- Ting Wang
- Department of Pharmaceutical Sciences, Shenyang Pharmaceutical University, P.O. Box 52, No. 103 Wenhua Road, Shenyang City, Liaoning Province 110016, PR China
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Nellis DF, Ekstrom DL, Kirpotin DB, Zhu J, Andersson R, Broadt TL, Ouellette TF, Perkins SC, Roach JM, Drummond DC, Hong K, Marks JD, Park JW, Giardina SL. Preclinical manufacture of an anti-HER2 scFv-PEG-DSPE, liposome-inserting conjugate. 1. Gram-scale production and purification. Biotechnol Prog 2005; 21:205-20. [PMID: 15903260 DOI: 10.1021/bp049840y] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A GMP-compliant process is described for producing F5cys-PEG-lipid conjugate. This material fuses with preformed, drug-loaded liposomes, to form "immunoliposomes" that bind to HER2/neu overexpressing carcinomas, stimulates drug internalization, and ideally improves the encapsulated drug's therapeutic index. The soluble, single-chain, variable region antibody fragment, designated F5cys, was produced in E. coli strain RV308 using high-density cultures. Affinity adsorption onto horizontally tumbled Streamline rProtein-A resin robustly recovered F5cys from high-pressure-disrupted, whole-cell homogenates. Two product-related impurity classes were identified: F5cys with mid-sequence discontinuities and F5cys with remnants of a pelB leader peptide. Low-pressure cation exchange chromatography, conducted at elevated pH under reducing conditions, enriched target F5cys relative to these impurities and prepared a C-terminal cysteine for conjugation. Site-directed conjugation, conducted at pH 5.9 +/- 0.1 with reaction monitoring and cysteine quenching, yielded F5cys-MP-PEG(2000)-DSPE. Low-pressure size exclusion chromatography separated spontaneously formed, high-molecular-weight conjugate micelles from low-molecular-weight impurities. When formulated at 1-2 mg/mL in 10 mM trisodium citrate, 10% sucrose (w/v), at pH 6.4 (HCl), the conjugate was stable when stored below -70 degrees C. Six scale-up lots were compared. The largest 40-L culture produced enough F5cys to manufacture 2,085 mg of conjugate, enough to support planned preclinical and future clinical trials. The conjugate was 93% pure, as measured by polyacrylamide gel electrophoresis. Impurities were primarily identified as product-related. Residual endotoxin, rProtein A, and genomic DNA, were at acceptable levels. This study successfully addressed a necessary step in the scale-up of immunoliposome-encapsulated therapeutics.
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Affiliation(s)
- David F Nellis
- SAIC-Frederick, Inc., National Cancer Institute at Frederick, PO Box B, Frederick, Maryland 21702, USA
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Chen T, Palmer LR, Fenske DB, Lam AMI, Wong KF, Cullis PR. Distal cationic poly(ethylene glycol) lipid conjugates in large unilamellar vesicles prepared by extrusion enhance liposomal cellular uptake. J Liposome Res 2005; 14:155-73. [PMID: 15676124 DOI: 10.1081/lpr-200033437] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Cationic poly(ethylene glycol)-lipid conjugates (CPLs), a class of lipid designed to enhance the interaction of liposomes with cells, possess the following architectural features: 1) a hydrophobic lipid anchor of distearoylphosphatidylethanolamine (DSPE); 2) a hydrophilic spacer of poly(ethylene glycol); and 3) a cationic head group prepared with 0, 1, 3, or 7 lysine residues located at the distal end of the PEG chain, giving rise to CPL possessing 1, 2, 4, or 8 positive charges, respectively (CPL1 to CPL8). Previously we have described the synthesis of CPL, have characterized the postinsertion of CPL into PEG-containing LUVs and SPLP (stabilized plasmid-lipid particles), have shown significant increases in the binding of CPL-LUV to cells, and have observed dramatically enhanced transfection (up to a million-fold) of cells with CPL-SPLP in the presence of calcium [Chen et al. (2000) Bioconjugate Chem. 11, 433-437; Fenske et al. (2001) Biochim. Biophys. Acta 1512, 259-272; Palmer et al. (2003) Biochim. Biophys. Acta 1611, 204-216]. In the present study, we examine a variety of CPL properties (such as polarity and CMC) and characterize CPL-vesicular systems formed by extrusion and examine their interaction with cells. While CPL polarity was observed to increase dramatically with increasing charge number, CMC values were all found to be low, in the range of other PEGylated lipids, and exhibited only a small increase, going from CPL1 (1.3 microM) to CPL8 (2 microM). The CPLs were almost quantitatively incorporated into large unilamellar vesicles (LUVs) prepared by the extrusion method and were evenly distributed across the lipid bilayer. Lower levels of incorporation were obtained when CPLs were incubated with preformed liposomes (DSPC/Chol, 55:45) at 60 degrees C. The binding of CPL-LUVs to BHK cells in vitro was found to be dependent on the distal charge density of the CPL rather than total surface charge. Liposomes possessing CPL4 or CPL8 were observed to bind efficiently to cell surfaces and enhance cellular uptake in BHK cells (as observed with both lipid and aqueous content markers), whereas those possessing CPL1 or CPL2 exhibited little or no binding. These results suggest new directions for the design of liposomal systems capable of in vivo delivery of both conventional and genetic (plasmid and antisense) drugs.
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Affiliation(s)
- Tao Chen
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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17
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Abstract
The present study evaluated the potential of archaesomes, prepared from the total polar lipids extracted from Methanobrevibacter smithii, as adjuvants for combination (multivalent) vaccines. Groups of Balb/c mice were immunized subcutaneously at day 0 and 21 with one of the following vaccines: trivalent vaccine formulated by the simultaneous co-encapsulation of bovine serum albumine (BSA), ovalbumin (OVA) and hen egg lysozyme (HEL) into archaeosomes (CEC vaccine); an univalent archaeosome vaccine (UVE vaccine) containing either BSA, OVA or HEL; or an admixture vaccine (AMC vaccine) consisting of the three UVE vaccines. Serum specific antibody (IgG + M) responses were determined at day 32, 112 and 203, and specific IgG1 and IgG2a responses were determined at day 112. Mice immunized with the CEC of AMC vaccine developed strong and sustained specific antibody responses to all three antigens at a magnitude similar to those seen in control mice immunized with UVE vaccines. Moreover, the serum BSA-, OVA-, and HEL-specific IgG1 and IgG2a levels in the CEC and AMC immunized mice were overall comparable to those of the UVE immunized control mice. Boosting CEC and AMC vaccinated mice with antigens alone at day 203 elicited strong antibody memory responses, comparable to those in the UVE vaccinated groups. These results show that archaeosomes could be used as adjuvants in developing combination vaccines.
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Affiliation(s)
- Girishchandra B Patel
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.
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18
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Abstract
In order to reconstitute the generation of COPII vesicles from synthetic liposomes, the minimum requirements are the coat components, Sar1p GTPase, Sec23/24p, Sec13/31p, and a nonhydrolyzable GTP analog such as GMP-PNP. However, in the presence of GTP, nucleotide hydrolysis by Sar1p renders the coat insufficiently stable to sustain vesicle budding. Sar1p GTPase activity was activated by the Sec23/24p GTPase-activating protein (GAP), and further accelerated 10-fold by Sec13/31p. In order to study GTP-dependent budding, we introduced the Sar1p guanine nucleotide exchange factor (GEF), Sec12p. We evaluated Sar1p activation by Sec12p and the dynamics of coat assembly and disassembly in the presence of both Sec12p and Sec23/24p. The cytoplasmic domain of Sec12p activated Sar1p with a turnover 10-fold higher than the GAP activity of Sec23p in the presence of Sec13/31p. As a result, the entire COPII coat remains stable in the presence of GTP. Here, we describe methods to purify Sec12p, real-time fluorescence assays to evaluate COPII coat formation, and the relevant kinetic analyses.
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Affiliation(s)
- Eugene Futai
- Department of Molecular and Cell Biology, University of California, Berkeley, USA
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19
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Abstract
Dynamin, unlike many GTPase superfamily members, exhibits a relatively rapid basal rate of GTP hydrolysis that is not rate-limited by GTP binding or GDP dissociation. Also unique to dynamin GTPase family members is their ability to self-assemble into rings and helical stacks of rings either in solution or onto lipid templates. Self-assembly stimulates dynamin's GTPase activity by >100-fold. Given these robust rates of GTP hydrolysis compared to most GTPases, GTP hydrolysis by dynamin can be easily measured using a simple colorimetic assay to detect released phosphate. We describe this assay and report variations in assay conditions that have contributed to the wide range of reported values for dynamin's basal and assembly-stimulated rates of GTP hydrolysis.
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Affiliation(s)
- Marilyn Leonard
- The Scripps Research Institute, Department of Cell Biology, La Jolla, California, USA
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20
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Abstract
We present a novel column chromatography technique for recovery and purification of lipid vesicles, which can be extended to other macromolecular assemblies. This technique is based on reversible binding of biotinylated lipids to monomeric avidin. Unlike the very strong binding of biotin and biotin-functionalized molecules to streptavidin, the interaction between biotin-functionalized molecules and monomeric avidin can be disrupted effectively by ligand competition from free biotin. In this work, biotin-functionalized lipids (biotin-PEG-PE) were incorporated into synthetic lipid vesicles (DOPC), resulting in unilamellar biotinylated lipid vesicles. The vesicles were bound to immobilized monomeric avidin, washed extensively with buffer, and eluted with a buffer supplemented with free biotin. Increasing the biotinyl lipid molar ratio beyond 0.53% of all lipids did not increase the efficiency of vesicle recovery. A simple adsorption model suggests 1.1 x 10(13) active binding sites/mL of resin with an equilibrium binding constant of K = 1.0 x 10(8) M(-1). We also show that this method is very robust and reproducible and can accommodate vesicles of varying sizes with diverse contents. This method can be scaled up to larger columns and/or high throughput analysis, such as a 96-well plate format.
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Affiliation(s)
- Boris Peker
- Biophysics Program, Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA
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21
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Shahinian S, Silvius JR. High-yield coupling of antibody Fab' fragments to liposomes containing maleimide-functionalized lipids. Methods Enzymol 2004; 387:3-15. [PMID: 15172154 DOI: 10.1016/s0076-6879(04)87001-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Affiliation(s)
- Serge Shahinian
- Department of Biochemistry,McGill University, Montreal, Quebec, Canada
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22
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Abstract
Liposomes containing isoniazid were obtained by extrusion of multilamellar phospholipid vesicles containing isoniazid, by ultrasound treatment, and from proliposomes. Optimal conditions for isolation of stable liposomes (200 nm in diameter) and the amount of incorporated isoniazid were determined by varying concentrations of phospholipids and isoniazid and by changing phospholipid composition.
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Affiliation(s)
- G M Sorokoumova
- M. V. Lomonosov Moscow State Academy of Fine Chemical Technology
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23
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Affiliation(s)
- Jeffrey K Mills
- Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708, USA
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24
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Affiliation(s)
- Jolanda M Smit
- Department of Medical Microbiology, Molecular Virology Section, University of Groningen, Ant. Deusinglaan 1, 9713 AV Groningen, The Netherlands
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25
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Abstract
Phospholipid-coated colloidal magnetic nanoparticles with mean magnetite core size of 8 nm are shown to be effective ion exchange media for the recovery and separation of proteins from protein mixtures. These particles have high adsorptive capacities (up to 1200 mg protein/mL adsorbent, an order of magnitude larger than the best commercially available adsorbents) and exhibit none of the diffusional resistances offered by conventional porous ion exchange media. Protein-laden particles are readily recovered from the feed solution using high-gradient magnetic filtration.
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Affiliation(s)
- Seyda Bucak
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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26
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Maguire LA, Zhang H, Shamlou PA. Preparation of small unilamellar vesicles (SUV) and biophysical characterization of their complexes with poly-l-lysine-condensed plasmid DNA. Biotechnol Appl Biochem 2003; 37:73-81. [PMID: 12578554 DOI: 10.1042/ba20020107] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Liposomes have numerous applications in the (bio)pharmaceutical industries as agents in the synthesis of new biomaterials for use in areas including gene delivery. There is currently a need to establish efficient scaleable methods for the manufacture of liposomes, and in the present paper we describe the operation of a new high-velocity jet homogenizer for downsizing of multilamellar large vesicles to produce small unilamellar vesicles (SUV). Measurements of size distribution of SUVs are presented and compared with mathematical simulations based on the solution of a population balance equation combined with computational-fluid-dynamics analysis of flow in the homogenizer. Anionic SUVs are produced by the new method and incubated with poly-L-lysine (PLL)-condensed plasmid DNA (pDNA) to generate complexes under different physico-chemical conditions. The colloidal properties of the resulting complexes, including their size and charge, are measured using a Zetasizer and the encapsulation efficiency is obtained experimentally using a Pico Green assay. The results show that between 85 and 95% of the PLL-pDNA condensed plasmids were encapsulated by the liposomes, the smaller liposomes being more effective in encapsulating the complexes.
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Affiliation(s)
- Leigh A Maguire
- Department of Biochemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
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27
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Affiliation(s)
- Joel A Cohen
- Department of Physiology, University of the Pacific School of Dentistry, 2155 Webster Street, San Francisco, California 94115, USA
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28
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Affiliation(s)
- Barbara Mui
- Inex Pharmaceutical Copre, Glenlyon Business Park1, 100-8900 Glenlyon Parkway, Burnaby, British Columbia, Canada V5J 5J8
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29
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Scott BL, Van Komen JS, Liu S, Weber T, Melia TJ, McNew JA. Liposome fusion assay to monitor intracellular membrane fusion machines. Methods Enzymol 2003. [PMID: 14610819 DOI: 10.1016/s0076-6879(03)72016-72013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Affiliation(s)
- Brenton L Scott
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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30
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Affiliation(s)
- Ramon Barnadas Rodríguez
- Unitat de Biofisica, Facultat de Medicine, Universitat Autònoma de Barcelona, Catalonia, 08193 Cerdanolya del Vallès, Spain
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31
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32
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Affiliation(s)
- Brenton L Scott
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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33
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Abstract
Dimyristoylphosphatidylethanolamine (DC(14:0)PE) and the dioleoyl analogue (DC(18:1cis)PE) were mixed with alpha-biotinylamido-omega-N-succinimidoxycarbonyl-poly(ethylene glycol) (NHS-PEG-biotin) and quantitatively converted to alpha-biotinylamido-omega-(dimyristoylphosphatidylethanolamino-carbonyl)polyethylene glycol (DC(14:0)PE-PEG-biotin) and the dioleoyl analogue DC(18:1cis)PE-PEG-biotin, respectively. As shown by thin-layer chromatography and 1H NMR spectroscopy, PEGylation of both phosphatidylethanolamine types went to completion if the reaction was performed in organic solvent in the presence of triethylamine. The resulting derivatives were successfully incorporated into both classical phospholipid vesicles and a phospholipid bilayer surrounding nanometer-sized magnetite cores. In the latter case, the so-called activated Stealth(1) magnetoliposomes were produced which very efficiently immobilized streptavidinylated alkaline phosphatase.
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Affiliation(s)
- Michael Hodenius
- Rheinisch-Westfälische Technische Hochschule Aachen, Prof. Pirlet-Strasse 1, D-52074, Aachen, Germany
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34
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Nguyen XT, Pabarue HA, Geyer RR, Shroyer LA, Estey LA, Parilo MS, Wilson KS, Prochaska LJ. Biochemical and biophysical properties of purified phospholipid vesicles containing bovine heart cytochrome c oxidase. Protein Expr Purif 2002; 26:122-30. [PMID: 12356479 DOI: 10.1016/s1046-5928(02)00503-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Liposomes containing bovine heart cytochrome c oxidase (COV) prepared by the cholate dialysis technique were purified from those devoid of the enzyme using discontinuous sucrose density ultra centrifugation to eliminate interference in proton-pumping assays. This technique was also used to purify liposomes containing cytochrome c oxidase depleted in subunit III (COV-III), a COX enzyme preparation with altered subunit structure, to assess if the technique could be applied to COX enzymes in which structural and functional changes have occurred. Upon discontinuous sucrose density ultra gradient ultracentrifugation, either COV or COV-III were separated into two bands. Liposomes devoid of enzyme sedimented into the 12% sucrose layer, whereas enzyme-containing liposomes (pCOV or pCOV-III) were found in the 13% sucrose layer. The yield of both pCOV or pCOV-III was greater than 60% (based on heme aa(3) content), suggesting a similar distribution of cytochrome c oxidase (COX) and subunit III-depleted enzyme (COX-III) in the purified liposomes. The number of COX or COX-III molecules per phospholipid vesicle in purified fractions was estimated to be two. Removal of subunit III (M(r)=29,918) from COX resulted in a 30% decrease in electron transfer activity (either in COV-III or pCOV-III) when compared with COV and pCOV, respectively. Both pCOV and pCOV-III exhibited low endogenous proton permeability, as assessed by possessing high respiratory control ratios (14 and greater) and by having similar valinomycin concentration dependencies for stimulation of electron transfer activity in the presence of saturating amounts of CCCP. COV-III and pCOV-III exhibited a 39-44% decrease in proton-pumping activity when compared with COV and pCOV. These results showed that the separation of COX containing liposomes from those lacking enzyme by sucrose density gradient centrifugation can be used to characterize the biophysical properties of these liposomes.
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Affiliation(s)
- Xuan-Thao Nguyen
- Department of Biochemistry and Molecular Biology, School of Medicine and College of Science and Mathematics, Wright State University, Dayton, OH 45435, USA
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35
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Abstract
Intensive efforts have been made to establish a novel, scalable liposomal preparation technique suitable for the entrapment of even large proteins into liposomes. We have developed a new technique based on the principles of the ethanol injection technique. Herein, the principal item is the crossflow injection module, specifically designed for this purpose. This unit has the benefit of defined and characterized injection streams and permits liposome manufacture regardless of production scale, as scale is determined only by the free disposable vessel volumes. Previous publications demonstrated that the crossflow injection technique that we have developed meets all of the above-mentioned requirements. The present paper describes the entire three-step production process, consisting of encapsulation, separation of non-entrapped protein by continuous crossflow filtration, and retrieval of rh-Cu/Zn-SOD by additional filtration. Results of consecutive lots were compared, based on well-defined quality criteria.
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Affiliation(s)
- Andreas Wagner
- Polymun Scientific, Immunbiologische Forschung GmbH, Vienna, Austria.
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36
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Abstract
The analytical separation and characterization of particles in the size range of sub-microm and microm diameters by capillary zone electrophoresis (CZE) has been reviewed. The theoretical basis, on which the mobility can be interpreted to provide information regarding characteristics of particle surface, has shortly been presented. Particular emphasis was put on the model dependence of that interpretation and the need in most applications to forego the classical idealized model of spherical particles with "smooth" surfaces and to apply more realistic models, which take the "hairy" surface of real particles into account. Some highlights of the literature on the CZE of polystyrene latex microspheres, organic and inorganic colloids, lipoprotein particles, viruses, liposomes, biological membrane vesicles, and biological cells have been discussed. Also summarized are the reports on the particle size dependence of mobility and peak broadening in CZE and on electrophoretic behavior of rodlike particles and particle aggregates. Finally, the effects of neutral polymers in the background electrolyte on particle mobility and peak width are reviewed.
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Affiliation(s)
- Sergey P Radko
- Biotechnology Department, Research Center for Medical Genetics, Russian Academy of Medical Sciences, Moscow, Russia
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37
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Abstract
Aim of the present paper was to investigate the influence of preparation parameters on the production of lipospheres (LS) for drug delivery. LS composed of triglycerides and monoglycerides were alternatively produced by melt dispersion technique, solvent evaporation or w/o/w double emulsion method. The influence of preparation parameters, such as (a) type and amount of lipids, (b) presence and concentration of surfactants, (c) stirring speed and (d) type of stirrer was studied. In the case of LS prepared by melt dispersion, the use of a lipid composition of cetyl alcohol/cholesterol (2:1, w/w), a 5% (w/w) gelatin solution (50 bloom grades) and 1000 rpm stirring speed resulted in the production of spherical particles, with high percentage of recovery (82%, w/w) a mean diameter of 80 microm and a narrow size distribution. In the case of LS prepared by solvent evaporation, the best results in terms of LS morphology, recovery and size distribution were obtained by the use of a lipid composition of tristearin/monostearate (66:34, w/w), a 1% (w/w) PVA solution, a 750 rpm stirring speed and a 55 mm three-blade turbine rotor. The solvent evaporation method resulted in the production of LS characterised by a smaller size (20 microm mean diameter) but poor mechanical properties with respect to particles with the same composition obtained by the melt dispersion technique (170 microm mean diameter). The use of a combination of lipids and a methacrylic polymer (Eudragit RS 100) overcame this problem, resulting in the production of spherical particles, with a narrower size distribution and good mechanical properties. Two lipophilic drugs, such as retinyl acetate and progesterone, and one hydrophilic drug, sodium cromoglycate (SCG), were encapsulated in LS as model compounds. Lypophilic drugs displayed satisfactory encapsulation efficiencies (over 70% w/w), while SCG was very scarcely encapsulated (about 2% w/w). To solve this drawback, the use of a w/o/w double emulsion strategy was proposed, enabling to increase the encapsulation of SCG up to 50% w/w. Finally, in vitro drug release studies were performed, showing that all drugs were released in a control manner. In particular. the retinyl acetate release efficacy within the first 8 h was 27% of the total amount of the drug, while in the same period, the amount of progesterone released was 63%. With regard to SCG containing LS, the release of the drug was largely influenced by the type of stabiliser of the primary emulsion, in any case the SCG release reached the 100% of the total amount of drug after 5 h from the beginning of the experiment.
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Affiliation(s)
- Rita Cortesi
- Department of Pharmaceutical Sciences, University of Ferrara, Italy
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38
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Abstract
Liposome researchers have created a hugh variety of liposomal drug carriers in the past thirty years mainly by small-scale laboratory techniques using more or less well defined raw materials. Only a few of these liposomal preparations have made their way to approved drugs for clinical use in humans so far. The review gives a critical literature survey over key technologies, which are used to evaluate an appropriate lipid formula and to prepare, size, load and sterilise liposomes. It also deals with quality and shelf stability aspects of liposomal drug carriers.
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Affiliation(s)
- M Brandl
- Univesitetet i Tromsø, Institutt for Farmasi, Avdeling for Galenisk Farmasi, N-9037 Tromsø, Norway
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39
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Conlan JW, Krishnan L, Willick GE, Patel GB, Sprott GD. Immunization of mice with lipopeptide antigens encapsulated in novel liposomes prepared from the polar lipids of various Archaeobacteria elicits rapid and prolonged specific protective immunity against infection with the facultative intracellular pathogen, Listeria monocytogenes. Vaccine 2001; 19:3509-17. [PMID: 11348718 DOI: 10.1016/s0264-410x(01)00041-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Protective immunity to intracellular bacterial pathogens usually requires the participation of specific CD8+ T cells. Natural exposure of the host to sublethal infection, or vaccination with attenuated live vaccines are the most effective means of eliciting prolonged protective cell-mediated immunity against this class of pathogens. The ability to replace these immunization strategies with defined sub-unit vaccines would represent a major advance for clinical vaccinology. The present study examines the ability of novel liposomes, termed archaeosomes, made from the polar lipids of various Archaeobacteria to act as self-adjuvanting vaccine delivery vehicles for such defined acellular antigens. Using infection of mice with Listeria monocytogenes as a model system, this study clearly demonstrates the ability of defined, archaeosome-entrapped antigens to elicit rapid and prolonged specific immunity against a prototypical intracellular pathogen. In this regard, all of the tested archaeosomes were superior to conventional liposomes.
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Affiliation(s)
- J W Conlan
- Institute for Biological Sciences, National Research Council of Canada, Room 3065, 100 Sussex Drive, Ont., K1A 0R6, Ottawa, Canada.
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40
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Affiliation(s)
- A Lee
- Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Johnson Research Foundation, Philadelphia, Pennsylvania 19104-6059, USA
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41
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Radko SP, Stastna M, Chrambach A. Size-dependent electrophoretic migration and separation of liposomes by capillary zone electrophoresis in electrolyte solutions of various ionic strengths. Anal Chem 2000; 72:5955-60. [PMID: 11140762 DOI: 10.1021/ac000661e] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The size-dependent electrophoretic migration and separation of liposomes was demonstrated and studied in capillary zone electrophoresis (CZE). The liposomes were extruded and nonextruded preparations consisting of phosphatidylcholine/phosphatidylglycerol/cholesterol in various ratios and ranging from 125 to 488 nm in mean diameter. When liposomes of identical surface charge density were subjected to CZE in Tris-HCl (pH 8) buffers of various ionic strengths (0.001-0.027), they migrated in order of their size. Size-dependent electrophoretic migration and separation of liposomes in CZE can be enhanced or brought about by decreasing the ionic strength of the buffer. It was shown that size-dependent migration is primarily a function of kappaR, where kappa(-1) is the thickness of the electric double layer (which can be derived from the ionic strength, I, of the buffer) and R, the liposome radius. Liposome mobility depends on kappaR and surface charge density in a manner consistent with that expected from the Overbeek-Booth electrokinetic theory. Thus, the relaxation effect appears to be the physical mechanism underlying the size-dependent electrophoretic separation of liposomes.
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Affiliation(s)
- S P Radko
- Section on Macromolecular Analysis, Laboratory of Cellular and Molecular Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-1580, USA
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42
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Abstract
We describe an efficient method for separating liposomes (large unilamellar vesicles, 120-150 nm diameter) from plasma lipoproteins employing fast protein liquid chromatography (FPLC). This method resolves very low density lipoprotein (VLDL), low-density lipoprotein, high-density lipoprotein, and other plasma components. Selective detection of liposomes (large unilamellar vesicles, 120-150 nm diameter) was achieved using either radiolabeled or fluorescent lipid probes. The liposomes were found to coelute with the earliest FPLC-eluting lipoprotein fraction, VLDL. The remaining plasma lipoprotein and protein components eluted at later times and were resolved from liposomes and VLDL. In order to separate VLDL from liposomes, we selectively precipitated the VLDL fraction from plasma using tungstophosphoric acid and magnesium chloride, prior to separation by FPLC. Furthermore, we demonstrate that this technique can be used to separate liposomes from lipoproteins in plasma samples collected after intravenous administration of liposomes to mice. This technique has wide application in studies of liposome stability in blood and, in particular, for the characterization of liposomal drug carrier systems.
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Affiliation(s)
- E Choice
- Department of Pharmacology & Therapeutics, University of British Columbia, 2176 Health Sciences Mall, Vancouver, British Columbia, V6T 1Z3, Canada.
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43
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Korgel BA, van Zanten JH, Monbouquette HG. Vesicle size distributions measured by flow field-flow fractionation coupled with multiangle light scattering. Biophys J 1998; 74:3264-72. [PMID: 9635780 PMCID: PMC1299667 DOI: 10.1016/s0006-3495(98)78033-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The separation method, flow field-flow fractionation (flow FFF), is coupled on-line with multiangle laser light scattering (MALLS) for simultaneous measurement of the size and concentration of vesicles eluting continuously from the fractionator. These size and concentration data, gathered as a function of elution time, may be used to construct both number- and mass-weighted vesicle size distributions. Unlike most competing, noninvasive methods, this flow FFF/MALLS technique enables measurement of vesicle size distributions without a separate refractive index detector, calibration using particle size standards, or prior assumptions about the shape of the size distribution. Experimentally measured size distributions of vesicles formed by extrusion and detergent removal are non-Gaussian and are fit well by the Weibull distribution. Flow FFF/MALLS reveals that both the extrusion and detergent dialysis vesicle formation methods can yield nearly size monodisperse populations with standard deviations of approximately 8% about the mean diameter. In contrast to the rather low resolution of dynamic light scattering in analyzing bimodal systems, flow FFF/MALLS is shown to resolve vesicle subpopulations that differ by much less than a factor of two in mean size.
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Affiliation(s)
- B A Korgel
- Chemical Engineering Department, University of California Los Angeles, 90095-1592, USA
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44
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Foia L, Costuleanu N, Pavel M. [The biological effects of liposome interactions with the endoplasmic reticulum]. Rev Med Chir Soc Med Nat Iasi 1998; 102:54-60. [PMID: 10756813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Liposome research is a thriving field at the confluence of biophysics, cell biology and medicine. The principal medical application of liposomes is based on their potential to act as carriers for a broad spectrum of drugs and other agents, including antigens with or without immunomodulators in vaccination. Treatment of peritoneal macrophages of rats with small unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC SUV) potentiated their activation for tumor cell lysis by endotoxins. The measurement of the fluorescence anisotropy of diphenylhexatriene showed a phase transition. No phase transition was observed in the rough endoplasmic reticulum membranes of macrophages either treated or not treated with cholesterol/DPPC SUV. The synergistic effect of DPPC SUV on the tumoricidal activity of macrophages induced by endotoxins appears to be correlated with the changes in the properties of the rough endoplasmic reticulum membranes. Both effects were transient; they had the same kinetics of induction and reversion.
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Affiliation(s)
- L Foia
- Disciplina de Biochimie, Facultatea de Stomatologie, Universitatea de Medicina şi Farmacie Gr. T. Popa, Iaşi
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45
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Abstract
The entrapment efficiency of three main methods used in the literature for the encapsulation of nucleic acids in liposomes were studied using 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes. In particular the reverse phase method, the dehydration/rehydration method, and the freeze/thawing method were compared to each other under standardised conditions, i.e. using in every case the same concentration of guest molecules (DNA, tRNA and ATP as low molecular weight analogue) and equally extruded liposomes. The percentage of entrapment strictly referred to the material localized inside the liposomes, i.e. particular care was devoted to ruling out the contribution of the nucleic acid material bound to the outer surface of the liposomes: this was eliminated by extensive enzymatic digestion prior to column chromatography. Depending on the conditions used, the percentage of the entrapped material varied between 10 and 54% of the initial amount. Further, the encapsulation efficiency was markedly affected by the salt concentration, by the size of liposomes, but to a lower degree by the molecular weight of the guest molecules. In general, we observed that the freeze/thawing encapsulation procedure was the most efficient one. In a second part of the work the freeze/thawing method was applied to encapsulate DNA (369 bp and 3368 bp, respectively) using liposomes obtained from POPC mixed with 1-10% charged cosurfactant, i.e. phosphatidylserine (PS) or didodecyldimethylammonium bromide (DDAB), respectively. Whereas PS had no significant effect, the entrapment efficiency went up to 60% in POPC/DDAB (97.5:2.5) liposomes. The large entrapment efficiency of DNA permits spectroscopic investigations of the DNA encapsulated in the water pool of the liposomes. UV absorption and circular dichroism spectra were practically the same as in water, indicating no appreciable perturbation of the electronic transitions or of the conformation of the entrapped biopolymer. This was in contrast to the DNA bound externally to the POPC/DDAB liposomes which showed significant spectral changes with respect to DNA dissolved in water.
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Affiliation(s)
- P A Monnard
- ETH-Zentrum, Institut für Polymere, Zürich, Switzerland
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46
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Gu JL, Nadler J, Rossi J. Use of a hammerhead ribozyme with cationic liposomes to reduce leukocyte type 12-lipoxygenase expression in vascular smooth muscle. Mol Cell Biochem 1997; 172:47-57. [PMID: 9278231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chemically synthesized hammerhead-type ribozymes targeted against the porcine leukocyte-type 12-lipoxygenase (LO) have been developed and studied. One chimeric ribozyme consists of DNA in the non-enzymatic portions, and RNA in the enzymatic core as well as two phosphorothioate internucleotide linkages at 3' terminus. The second ribozyme consists of ribonucleotide sequences generated by in vitro transcription. In this chapter we describe methodologies to first analyze the ribozyme catalytic activity in vitro by studying cleavage of target RNA in vitro. The subsequent sections will describe how to target the catalytic ribozyme and deliver it to porcine vascular smooth muscle cells (PVSMC) by a liposome-mediated method. Finally ways to evaluate its activity to inhibit expression of the 12-LO mRNA will be presented. These results demonstrate the feasibility of using ribozymes as novel candidates for therapeutic agents to block specific gene expression in vascular cells.
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Affiliation(s)
- J L Gu
- Department of Diabetes, Endocrinology and Metabolism, City of Hope Medical Center, Duarte, CA 91010, USA
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47
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Watanabe J, Asaka Y, Mino K, Kanamura S. Preparation of liposomes that mimic the membrane of endoplasmic reticulum of rat hepatocytes. J Electron Microsc (Tokyo) 1996; 45:171-176. [PMID: 8691092 DOI: 10.1093/oxfordjournals.jmicro.a023429] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
To examine the interaction between biomembranes and membrane-bound proteins, large unilamellar liposomes have been required. In the present study, we prepared liposomes from a mixture of phospholipids having a phospholipid composition similar to that in the endoplasmic reticula (microsomes) of rat hepatocytes by eight different methods. The resulting liposomes were examined by a combination of the freeze-fracture-replica procedure with biochemical methods. The freeze-thawing method of Pick (1981) gave the best results; large unilamellar liposomes that mimic the membrane of endoplasmic reticulum were obtained. Liposomes made by this method are thus suitable for analysis of the interaction between the endoplasmic reticulum membrane and membrane-bound proteins.
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Affiliation(s)
- J Watanabe
- Department of Anatomy, Kansai Medical University, Osaka, Japan
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48
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Sorace JM, Rollins S, Aniagolu JU, Mergner WJ, Cole K, Swartz GM, Green SJ. Role of atheroma liposomes and malondialdehyde-modified low-density lipoproteins in complement activation. Pathobiology 1996; 64:73-8. [PMID: 8888272 DOI: 10.1159/000164012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We investigated the ability of atheroma-associated liposomes and malondialdehyde (MDA)-modified low-density lipoproteins (MDA-LDL) to activate complement. Complement activation markers C3a, Bb, C4d and SC5b-9 were measured in both normal and complement-deficient sera. We found that MDA-LDL was able to generate C3a and SC5b-9, predominantly by the alternative pathway. High-density lipoproteins modified with MDA were also capable of C3a generation although to a lesser degree. The presence of atheroma-associated liposomes did not result in detectable levels of complement activation markers. We conclude that MDA-modified lipoproteins may represent a possible source for complement activation within atherosclerotic lesions.
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Affiliation(s)
- J M Sorace
- Department of Pathology (113), Baltimore VAMC, MD 21201, USA
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Bejan A, Turcu G. Liposomes: presentation and actual applicative trends in medicine. Rom J Intern Med 1995; 33:141-9. [PMID: 8646185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In this paper the main aspects of characterization, handling and applications of liposomes are presented. In the last 25 years much attention has been focused to liposomal systems for optimization of the drug targeting. Several pathways to optimize the drug action of liposomes in various situations as cancer, microbial therapy, vaccines, oral therapy and diagnosis were tested. Certain applications of liposomes especially those implying the phagocytic cells sustain a real interest for industrial applications.
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Affiliation(s)
- A Bejan
- Institute of Atomic Physics, IFIN, Măgurele-Bucharest, Romania
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Lalmanach Girard AC, Guillaumin JM, Thibault G, Rupin A, De Russé J, Bardos P. Inhibition of induced lymphocyte proliferation by lipid and protein components of the syncytiotrophoblast plasma membrane. Am J Reprod Immunol 1995; 33:182-9. [PMID: 7646770 DOI: 10.1111/j.1600-0897.1995.tb00883.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
PROBLEM The aim of this work was to define the respective responsibilities of the lipid and protein components of syncytiotrophoblast plasma membranes on the inhibition of lymphocyte proliferation induced in vitro. METHOD A fractionation method using octyl-beta-D-glucopyranoside enabled lipoprotein, lipid, and protein fractions to be isolated from the membrane. RESULTS The lipid fraction was shown nonspecifically to inhibit lymphocyte proliferation, to a lower extent compared with the native membrane. Alternatively, the protein fraction used as a proteoliposome contained the totality of the cytostatic effect of the native fraction. CONCLUSION These results are discussed generally in the context of the immunoregulatory role of membrane lipids and proteins and in relation to the local properties of syncytiotrophoblast plasma membrane components in fetal graft tolerance.
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