New multivalent cationic lipids reveal bell curve for transfection efficiency versus membrane charge density: lipid–DNA complexes for gene delivery

Ahmad, Ayesha; Evans, Heather M.; Ewert, Kai K.; George, Cyril X.; Samuel, Charles E.; Safinya, Cyrus R.

doi:10.1002/jgm.717

Cited by 176 publications

(391 citation statements)

References 38 publications

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“…44,45 Another important factor for the transfection efficiency is the structure of the formed complexes, especially if the composition is not optimized. The efficiency of the transfection is not only dependent on the entrance of the complex into the cell but also the escape of the complexes from the endosomal membrane.…”

Section: Introductionmentioning

confidence: 99%

“…For lamellar complexes, this can be achieved for membrane charge densities that are sufficiently high. 44,45 Inverted hexagonal structures are very efficient in releasing the DNA into the cell since these structures are much more prone to fusion. 45 With this in mind, one can rationalize that the presence of hydrophilic groups in the headgroups of the lipids can induce changes in terms of lipid packing that can lead to substantial differences in the self-assembly structures that are formed, when compared with similar lipids without those groups.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Headgroup on DNA−Cationic Surfactant Interactions

Dasgupta¹,

Das²,

Dias³

et al. 2007

J. Phys. Chem. B

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The interaction behavior of DNA with different types of hydroxylated cationic surfactants has been studied. Attention was directed to how the introduction of hydroxyl substituents at the headgroup of the cationic surfactants affects the compaction of DNA. The DNA-cationic surfactant interaction was investigated at different charge ratios by several methods like UV melting, ethidium bromide exclusion, and gel electrophoresis. Studies show that there is a discrete transition in the DNA chain from extended coils (free chain) to a compact form and that this transition does not depend substantially on the architecture of the headgroup. However, the accessibility of DNA to ethidium bromide is preserved to a significantly larger extent for the more hydrophilic surfactants. This was discussed in terms of surfactant packing. Observations are interpreted to reflect that the surfactants with more substituents have a larger headgroup and therefore form smaller micellar aggregates; these higher curvature aggregates lead to a less efficient, "patch-like" coverage of DNA. The more hydrophilic surfactants also presented a significantly lower cytotoxicity, which is important for biotechnological applications.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Headgroup on DNA−Cationic Surfactant Interactions

Dasgupta¹,

Das²,

Dias³

et al. 2007

J. Phys. Chem. B

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“…Generally speaking, H C II complexes exhibit higher TEs than L C α complexes. A third parameter is the charge density (per unit area) of the lipoplex membranes, which can be varied by mixing different ratios of CLs and NLs, and by using multivalent CLs [15].Further improvement of the therapeutic efficacy of lipid vectors requires better understanding of their mechanism of transfection, and the biophysical parameters of the CL-DNA complexes that influence it. Transfection is viewed as a three-stage process starting with adsorption and entry (via endocytosis) of the CL-DNA complex into the cell, followed by lipoplex degradation, and finally ending with the release of the DNA, making the latter available for expression [13,16,17].…”

mentioning

confidence: 99%

mentioning

confidence: 99%

The thermodynamics of endosomal escape and DNA release from lipoplexes

Avital

Grønbech‐Jensen

Farago

2016

Phys. Chem. Chem. Phys.

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Complexes of cationic and neutral lipids and DNA (lipoplexes) are emerging as promising vectors for gene therapy applications. Their appeal stems from their non pathogenic nature and the fact that they self-assemble under conditions of thermal equilibrium. Lipoplex adhesion to the cell plasma membrane initiates a three-stage process termed transfection, consisting of (i) endocytosis, (ii) lipoplex breakdown, and (iii) DNA release followed by gene expression. As successful transfection requires lipoplex degradation, it tends to be hindered by the lipoplex thermodynamic stability; nevertheless, it is known that the transfection process may proceed spontaneously. Here, we use a simple model to study the thermodynamic driving forces governing transfection. We demonstrate that after endocytosis [stage (i)], the lipoplex becomes inherently unstable. This instability, which is triggered by interactions between the cationic lipids of the lipoplex and the anionic lipids of the enveloping plasma membrane, is entropically controlled involving both remixing of the lipids and counterions release. Our detailed calculation shows that the free energy gain during stage (ii) is approximately linear in Φ+, the mole fraction of cationic lipids in the lipoplex. This free energy gain, ∆F , reduces the barrier for fusion between the enveloping and the lipoplex bilayers, which produces a hole allowing for DNA release [stage (iii)]. The linear relationship between ∆F and the fraction of cationic lipids explains the experimentally observed exponential increase of transfection efficiency with Φ+ in lamellar lipoplexes.Somatic gene therapy holds great promise for future medical applications including, for example, new treatments for various inherited diseases and cancers [1]. Within this approach, an attempt is made to replace damaged genes with properly functioning ones. The core of the process, called transfection, includes the key steps of transferring foreign DNA into a target cell, followed by expression of the genetic information. Complexes composed of cationic lipids (CLs) and DNA, designated lipoplexes, constitute one of the most promising non-viral gene delivery systems [2][3][4]. Though their transfection efficiency (TE) is, in general, inferior to that of viral vectors, lipoplexes have the advantage of triggering low immune response, and being non-pathogenic [4][5][6][7]. Furthermore, lipoplexes allow transfer of larger DNA segments. Their production does not require sophisticated engineering, since they form spontaneously in aqueous solutions when DNA molecules are mixed with CLs and neutral lipids (NLs) [8][9][10][11]. The main thermodynamic driving force for lipoplex formation is the entropic gain stemming from the release of the tightly bound counterions from the DNA and the lipid bilayers. X-ray diffraction experiments have revealed several liquid crystalline phases of CL-DNA complexes. The two most prominent structures are: (i) a lamellar phase (L C α ), with 2D smectic array of DNA within lipid bilayers [8], and (ii) an i...

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“…9,81 Similarly, higher lipoplex charge ratios reduce expression despite increased internalization and an improved ability to destabilize endosomes; the higher charge density is thought to prevent dissociation, thereby rendering DNA unavailable for transcription. 123,124 While the mechanisms of intracellular dissociation remain unknown, they are thought to involve displacement of DNA from the carrier by anionic lipids or proteins in the cytoplasm or to result from the large excess of DNA and RNA in the nucleus. 15,74,125 The potential role of RNA in DNA release from polyplexes is supported by observations that PEI accumulates near nucleoli and does not interact with chromosomal DNA.…”

Section: Gene Expressionmentioning

confidence: 99%

Toward Development of Artificial Viruses for Gene Therapy: A Comparative Evaluation of Viral and Non‐viral Transfection

Douglas¹

2008

Biotechnology Progress

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Problems related to the safety and efficacy of gene therapies have checked the enthusiasm once surrounding this field, though it remains a promising approach for the treatment of numerous diseases. Despite the high transfection efficiencies attainable using viral vectors, manufacturing difficulties, safety concerns, and limitations related to targeting and plasmid size have prompted considerable research into the development of non‐viral vectors. Non‐viral vectors demonstrate low toxicity, low immunogenicity, and ease of manufacture. However, they have not yet achieved the transfection efficiencies displayed by viruses. The inability to explain or predict transfection efficiencies results, in part, from insufficient understanding of the intracellular processes involved in gene delivery. Increasingly, research has been undertaken to probe the processes involved in overcoming the major obstacles to vector‐mediated transfection: (1) internalization, (2) intracellular trafficking, (3) escape to the cytosol, (4) nuclear translocation, and (5) gene transcription/expression. This paper reviews and compares the pathways and techniques involved in successful viral and non‐viral transfection. In addition, this review provides evidence that non‐viral vector development has been pursued successfully thus far, producing systems capable of evading almost all major obstacles to transfection. Evaluating the abilities of non‐viral and viral vectors to overcome specific cellular barriers reveals that the greatest advantage of viral vectors may be related to viral DNA, which is transcribed considerably more efficiently than plasmid DNA. Further study in this area should enable the development of non‐viral vectors that transfect as efficiently as viral vectors.

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New multivalent cationic lipids reveal bell curve for transfection efficiency versus membrane charge density: lipid–DNA complexes for gene delivery

Cited by 176 publications

References 38 publications

Effect of Headgroup on DNA−Cationic Surfactant Interactions

Effect of Headgroup on DNA−Cationic Surfactant Interactions

The thermodynamics of endosomal escape and DNA release from lipoplexes

Toward Development of Artificial Viruses for Gene Therapy: A Comparative Evaluation of Viral and Non‐viral Transfection

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