Effects of the nanostructure of dendrimer/DNA complexes on their endocytosis and gene expression

Shu Fen Peng, Chun Jen Su, Ming Cheng Wei, Chun Yu Chen, Zi Xian Liao, Po Wei Lee, Hsin Lung Chen*, Hsing Wen Sung

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

72 Scopus citations

Abstract

Cationic dendrimers constitute a potential nonviral vector for gene therapy due to their ability of forming electrostatic complexes with DNA (dendriplexes). However, the supramolecular structure of dendriplexes and its impact on the cellular uptake and gene transfection remain largely unknown. Using synchrotron small angle X-ray scattering, here we show that DNA in complexes with poly(amidoamine) (PAMAM) G4 dendrimers exhibited three distinct packaging states modulated by the degree of their protonation (dp). Our structure characterization suggests that the nanostructure of DNA in dendriplexes transformed from square-packed straightened chains (dp/0.1) to hexagonally-packed superhelices (dp/0.3) and eventually to a beads-on-string configuration (dp/0.6 and dp/0.9). The transfection efficiency in HT1080 cells significantly enhanced when the dp value was increased from 0.1 to 0.3. This enhancement was due to a higher positive surface charge of dendriplexes formed at higher dp, which facilitated adherence of test dendriplexes to the negatively charged cell membranes for the subsequent endocytosis. Although the surface charge of dendriplexes still increased accordingly, further increase of the dendrimer dp value to 0.9 reduced the transfection efficiency. This unexpected suppression of transfection may be attributed to the wrapping of DNA around dendrimers that frustrates the interaction between dendrimer and cholesterol in the membrane raft via the caveola-mediated endocytosis. These results can be used for the rational design of dendrimer-based gene delivery devices.

Original languageEnglish
Pages (from-to)5660-5670
Number of pages11
JournalBiomaterials
Volume31
Issue number21
DOIs
StatePublished - 07 2010
Externally publishedYes

Keywords

  • Cellular uptake
  • Gene therapy
  • Nonviral vector
  • Synchrotron small angle X-ray scattering
  • Transfection efficiency

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