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Reducible DNA nanoparticles enhance in vitro gene transfer via an extracellular mechanism.

ABSTRACT: We developed polylysine based DNA nanoparticles (DNA NPs) that contain disulfide linkage in the carrier and demonstrated that this reducible DNA NP enhances in vitro gene transfer via an extracellular mechanism. Polylysine was conjugated through an N-terminal cysteine to a polyethylene glycol chain (PEG) by either a disulfide bond (SS) or a thioether bond (CS), and the resulting PEG-peptide conjugates were used to compact plasmid DNA into reducible SS-DNA NPs or non-reducible CS-DNA NPs with identical physical properties. SS-DNA NPs mediated more than 10-fold higher in vitro gene transfer. Others have suggested that disulfide bonds in synthetic gene carriers undergo cleavage in the reducing environment inside the cell, allowing increased intracellular DNA release. In this study, however, both higher cellular uptake of SS-DNA NPs and inhibition of SS-DNA NP mediated in vitro gene transfer by blocking extracellular free thiols suggested an extracellular mechanism. DePEGylation of SS-DNA NPs by extracellular thiols caused aggregation which might lead to higher cellular uptake and higher transgene expression. A series of SS-DNA NPs prepared with stabilized disulfide bonds survived the extracellular environment without aggregation but lost the superior gene transfer ability, indicating that, in our system, intracellular mechanisms are not involved. These results provided further insight into the mechanisms of in vitro gene transfer enhancement by introducing reducible linkages, contributing to the rational design of more efficient non-viral gene delivery systems.

SUBMITTER: Sun W

PROVIDER: S-EPMC3031909 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Reducible DNA nanoparticles enhance in vitro gene transfer via an extracellular mechanism.

Sun Wenchao W Davis Pamela B PB

Journal of controlled release : official journal of the Controlled Release Society 20100512 1

We developed polylysine based DNA nanoparticles (DNA NPs) that contain disulfide linkage in the carrier and demonstrated that this reducible DNA NP enhances in vitro gene transfer via an extracellular mechanism. Polylysine was conjugated through an N-terminal cysteine to a polyethylene glycol chain (PEG) by either a disulfide bond (SS) or a thioether bond (CS), and the resulting PEG-peptide conjugates were used to compact plasmid DNA into reducible SS-DNA NPs or non-reducible CS-DNA NPs with ide ...[more]

PMID: 20438780

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Project description:Effective delivery is the primary barrier against the clinical translation of gene therapy. Yet there remains too much unknown in the gene delivery mechanisms, even for the most investigated polymeric carrier (i.e., PEI). As a consequence, the conflicting results have been often seen in the literature due to the large variability in the experimental conditions and operations. Therefore, some key parameters should be identified and thus strictly controlled in the formulation process. Methods: The effect of the formulation processing parameters (e.g., concentration or mixture volume) and the resulting nanostructure properties on gene transfection have been rarely investigated. Two types of the PEI/DNA nanoparticles (NPs) were prepared in the same manner with the same dose but at different concentrations. The microstructure of the NPs and the transfection mechanisms were investigated through various microscopic methods. The therapeutic efficacy of the NPs was demonstrated in the cervical subcutaneous xenograft and peritoneal metastasis mouse models. Results: The high-concentration process (i.e., small reaction-volume) for mixture resulted in the large-sized PEI/DNA NPs that had a higher efficiency of gene transfection, compared to the small counterpart that was prepared at a low concentration. The microstructural experiments showed that the prepared small NPs were firmly condensed, whereas the large NPs were bulky and botryoid-shaped. The large NPs entered the tumor cells via the macropinocytosis pathway, and then efficiently dissociated in the cytoplasm and released DNA, thus promoting the intranuclear delivery. The enhanced in vivo therapeutic efficacy of the large NPs was demonstrated, indicating the promise for local-regional administration. Conclusion: This work provides better understanding of the effect of formulation process on nano-structural properties and gene transfection, laying a theoretical basis for rational design of the experimental process.

Dataset Information

Reducible DNA nanoparticles enhance in vitro gene transfer via an extracellular mechanism.

Publications

Reducible DNA nanoparticles enhance in vitro gene transfer via an extracellular mechanism.

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