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Synthesis and characterization of mannosylated pegylated polyethylenimine as a carrier for siRNA
Journal article   Peer reviewed

Synthesis and characterization of mannosylated pegylated polyethylenimine as a carrier for siRNA

NaJung Kim, Dahai Jiang, Ashley M Jacobi, Kim A Lennox, Scott D Rose, Mark A Behlke and Aliasger K Salem
International journal of pharmaceutics, Vol.427(1), pp.123-133
05/01/2012
DOI: 10.1016/j.ijpharm.2011.08.014
PMCID: PMC3237934
PMID: 21864664
url
https://www.ncbi.nlm.nih.gov/pmc/articles/3237934View
Open Access

Abstract

Regulation of gene expression using small interfering RNA (siRNA) is a promising strategy for research and treatment of numerous diseases. In this study, we develop and characterize a delivery system for siRNA composed of polyethylenimine (PEI), polyethylene glycol (PEG), and mannose (Man). Cationic PEI complexes and compacts siRNA, PEG forms a hydrophilic layer outside of the polyplex for steric stabilization, and mannose serves as a cell binding ligand for macrophages. The PEI-PEG-mannose delivery system was constructed in two different ways. In the first approach, mannose and PEG chains are directly conjugated to the PEI backbone. In the second approach, mannose is conjugated to one end of the PEG chain and the other end of the PEG chain is conjugated to the PEI backbone. The PEI-PEG-mannose delivery systems were synthesized with 3.45–13.3 PEG chains and 4.7–3.0 mannose molecules per PEI. The PEI-PEG-Man-siRNA polyplexes displayed a coarse surface in Scanning Electron Microscopy (SEM) images. Polyplex sizes were found to range from 169 to 357nm. Gel retardation assays showed that the PEI-PEG-mannose polymers are able to efficiently complex with siRNA at low N/P ratios. Confocal microscope images showed that the PEI-PEG-Man-siRNA polyplexes could enter cells and localized in the lysosomes at 2h post-incubation. Pegylation of the PEI reduced toxicity without any adverse reduction in knockdown efficiency relative to PEI alone. Mannosylation of the PEI-PEG could be carried out without any significant reduction in knockdown efficiency relative to PEI alone. Conjugating mannose to PEI via the PEG spacer generated superior toxicity and gene knockdown activity relative to conjugating mannose and PEG directly onto the PEI backbone.
RNA interference Luciferase Mannose siRNA HPRT Gene medicine Nanoparticles Polyethylenimine Nanoplexes PEG Polyethylene glycol PEI Polyplexes non-viral

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