PEG grafting of polyethylenimine (PEI) exerts different effects on DNA transfection and siRNA-induced gene targeting efficacy
- 1 January 2008
- journal article
- research article
- Published by Taylor & Francis Ltd in Journal of Drug Targeting
- Vol. 16 (2), 124-139
- https://doi.org/10.1080/10611860701849058
Abstract
Background: Gene targeting by RNA interference (RNAi) is mediated through small interfering RNA (siRNA), which, as plasmid DNA molecules, can be delivered into cells by polyethylenimines (PEI). Grafting with poly(ethylene glycol) has been introduced previously to improve PEI biocompatibility; however, data on the effects of PEGylation have been somewhat contradictory and various PEI(-PEG) need to be evaluated independently for DNA transfection and siRNA gene targeting efficacies. Aim: We directly compare plasmid DNA transfection and siRNA-mediated gene targeting efficacies, employing a larger set of polyethylenimine-graft-poly(ethylene glycol) (PEI-g-PEG; PEI(-PEG)) with different molecular weights and degrees of PEG substitution. Method: We performed tissue culture-based bioassays on DNA transfection and siRNA-mediated targeting efficacies as well as on toxicity and cellular nucleic acid uptake, and, using sensitive assays based on radioactive labelling, physicochemically characterize the complexes regarding the degree of nucleic acid complexation and complex stabilities under various conditions. Results: In contrast to the DNA transfection efficacy, siRNA-mediated gene targeting is much less dependent on the PEGylation of PEI or on the N/P (= PEI nitrogen/nucleic acid phosphate) ratio. A more detailed analysis reveals that, in order to define optimal N/P ratios for DNA transfection, complex toxicities and nucleic acid uptake are the most critical parameters. In contrast, at optimal N/P ratios, complex stabilities and complexation efficacies determine PEI(-PEG)/DNA transfection efficacies and the major differences between various PEI(-PEG) are observed. All these parameters are less critical for PEI(-PEG)/siRNA gene targeting efficacy. Thus, our data lead to the distinction between three PEI(-PEG) groups, which relies on the differences in transfection rather than gene targeting efficacies, and which is correlated with the molecular weights and degrees of PEG substitution. Conclusion: In contrast to PEI(-PEG)/DNA complexes, a broader panel of PEI-PEG are capable of siRNA-mediated gene targeting. Thus, PEG grafting of PEI requires a separate evaluation of siRNA and DNA complexes, which expands the portfolio of available PEI(-PEG) for the preparation of non-toxic, biocompatible siRNA delivery reagents for the induction of RNAi.Keywords
This publication has 36 references indexed in Scilit:
- An Acetal-Based PEGylation Reagent for pH-Sensitive Shielding of DNA PolyplexesBioconjugate Chemistry, 2007
- Thyroid hormone (T3)-modification of polyethyleneglycol (PEG)-polyethyleneimine (PEI) graft copolymers for improved gene delivery to hepatocytesBiomaterials, 2007
- Influence of Polyethylene Glycol Chain Length on the Physicochemical and Biological Properties of Poly(ethylene imine)-graft-Poly(ethylene glycol) Block Copolymer/SiRNA PolyplexesBioconjugate Chemistry, 2006
- Trastuzumab−Polyethylenimine−Polyethylene Glycol Conjugates for Targeting Her2-Expressing TumorsBioconjugate Chemistry, 2006
- A low molecular weight fraction of polyethylenimine (PEI) displays increased transfection efficiency of DNA and siRNA in fresh or lyophilized complexesJournal of Controlled Release, 2006
- Comparative Evaluation of Target-Specific GFP Gene Silencing Efficiencies for Antisense ODN, Synthetic siRNA, and siRNA Plasmid Complexed with PEI−PEG−FOL ConjugateBioconjugate Chemistry, 2005
- Poly(ethylene imine)–Poly(ethylene glycol) Copolymers Facilitate Efficient Delivery of Antisense Oligonucleotides to Nuclei of Mature Muscle Cells of mdx MiceHuman Gene Therapy, 2005
- RNAi-mediated gene-targeting through systemic application of polyethylenimine (PEI)-complexed siRNA in vivoGene Therapy, 2004
- Purification of polyethylenimine polyplexes highlights the role of free polycations in gene transferThe Journal of Gene Medicine, 2004
- Delivery of unmodified bioactive ribozymes by an RNA-stabilizing polyethylenimine (LMW-PEI) efficiently down-regulates gene expressionGene Therapy, 2002