A Sustained, Cytoplasmic Transgene Expression System Delivered by Cationic Liposomes

Gao, Xiang; Jaffurs, Daniel; Robbins, Paul D.; Huang, Leaf

doi:10.1006/bbrc.1994.1578

Cited by 42 publications

(23 citation statements)

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“…In order to achieve and sustain efficacy, repeat dosing is very likely necessary in most gene therapy protocols, especially non-viral, that is neither multiplication-competent nor can integrate the gene into the host genome. Also, the duration of expression is usually quite short with liposomal vectors [45,104]. Immunogenicity of lipoplexes might preclude repeat administration.…”

Section: (B) Immunogenicitymentioning

confidence: 98%

“…The transfection is dependent on cell cycle, occurring mainly during mitosis, when the nuclear membrane is disrupted [100]. Methods to address this problem include the use of nuclear localization signal peptides, conjugated to vector [101] or directly to plasmid [102,103], to direct nuclear entry, or to completely bypass the requirement for nuclear transport by using cytoplasmic expression systems like T7 autogene [104,105].…”

Section: (G) Nuclear Entrymentioning

confidence: 99%

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Structure-Activity Relationship in Cationic Lipid Mediated Gene Transfection

Niculescu‐Duvaz¹,

Heyes²,

Springer³

2003

CMC

141

112

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Non-viral synthetic vectors for gene delivery represent a safer alternative to viral vectors. Their main drawback is the low transfection efficiency, especially in vivo. Among the non-viral vectors currently in use, the cationic liposomes composed of cationic lipids are the most common. This review discusses the physicochemical properties of cationic lipids, the formation, macrostructure and specific parameters of the corresponding formulated liposomes, and the effect of all these parameters on transfection efficiency. The optimisation of liposomal vectors requires both the understanding of the biological variables involved in the transfection process, and the effect of the structural elements of the cationic lipids on these biological variables. The biological barriers relevant for in vitro and in vivo transfection are identified, and solutions to overcome them based on rational design of the cationic lipids are discussed. The review focuses on the relationship between the structure of the cationic lipid and the transfection activity. The structure is analysed in a modular manner. The hydrophobic domain, the cationic head group, the backbone that acts as a scaffold for the other domains, the linkers between backbone, hydrophobic domain and cationic head group, the polyethyleneglycol chains and the targeting moiety are identified as distinct elements of the cationic lipids used in gene therapy. The main chemical functionalities used to built these domains, as well as overall molecular features such as architecture and geometry, are presented. Studies of structure-activity relationships of each cationic lipid domain, including the authors', and the trends identified by these studies, help furthering the understanding of the mechanism governing the formation and behaviour of cationic liposomes in gene delivery, and therefore the rational design of new improved cationic lipids vectors capable of achieving clinical significance.

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Section: (B) Immunogenicitymentioning

confidence: 98%

Section: (G) Nuclear Entrymentioning

confidence: 99%

Structure-Activity Relationship in Cationic Lipid Mediated Gene Transfection

Niculescu‐Duvaz¹,

Heyes²,

Springer³

2003

CMC

141

112

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“…The use of cytoplasmic expression systems with T7 RNA polymerase capable of ensuing cytoplasmic expression of the transfected genes has been demonstrated to be an elegant way to avoid nuclear barrier of transfection pathways. [25][26][27][28][29] Experiments conducted with lipid 1 using both pCMVLuc and pT7Luc plasmids in 293T7 cell lines revealed that the transfection efficiency was not sensitive to either cholesterol-to-lipid 1 molar ratios (in the range 1:2-3:1) or to the lipid 1-to-DNA charge ratios (in the range 3.5-1.3) (Figure 1). The observed lower transfection efficiencies for pT7Luc compared to that for pCMVLuc could result from the low level of the T7 RNA polymerase present in 293T7 cells and/or the weak strength of the promoter.…”

Section: Transfection Efficiencymentioning

confidence: 99%

Single histidine residue in head-group region is sufficient to impart remarkable gene transfection properties to cationic lipids: evidence for histidine-mediated membrane fusion at acidic pH

et al. 2003

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Presence of endosome-disrupting multiple histidine functionalities in the molecular architecture of cationic polymers, such as polylysine, has previously been demonstrated to significantly enhance their in vitro gene delivery efficiencies. Towards harnessing improved transfection property through covalent grafting of endosome-disrupting single histidine functionality in the molecular structure of cationic lipids, herein, we report on the design, the synthesis and the transfection efficiency of two novel nonglycerol-based histidylated cationic amphiphiles. We found that L-histidine-(N,N-di-n-hexadecylamine)ethylamide (lipid 1) and L-histidine-(N,N-di-n-hexadecylamine,-N-methyl)ethylamide (lipid 2) in combination with cholesterol gave efficient transfections into various cell lines. The transfection efficiency of Chol/lipid 1 lipoplexes into HepG2 cells was two order of magnitude higher than that of FuGENE TM 6 and DC-Chol lipoplexes, whereas it was similar into A549, 293T7 and HeLa cells. A better efficiency was obtained with Chol/lipid 2 lipoplexes when using the cytosolic luciferase expression vector (pT7Luc) under the control of the bacterial T7 promoter. Membrane fusion activity measurements using fluorescence resonance energy transfer (FRET) technique showed that the histidine head-groups of Chol/lipid 1 liposomes mediated membrane fusion in the pH range 5-7. In addition, the transgene expression results using the T7Luc expression vector convincingly support the endosome-disrupting role of the presently described mono-histidylated cationic transfection lipids and the release of DNA into the cytosol. We conclude that covalent grafting of a single histidine amino acid residue to suitable twin-chain hydrophobic compounds is able to impart remarkable transfection properties on the resulting mono-histidylated cationic amphiphile, presumably via the endosome-disrupting characteristics of the histidine functionalities.

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“…Cationic liposomes show cytotoxicity, 23) and it is necessary to take great care when cationic carriers are used as pCyclin A-Luc and PLL were mixed at the indicated weight ratios and then subjected to agarose gel electrophoresis. After electrophoresis, the gels were stained with ethidium bromide to visualize plasmid DNA.…”

Section: Resultsmentioning

confidence: 99%