Polyethylenimine (PEI)/siRNA-Mediated Gene Knockdown In Vitro and In Vivo

  • Sabrina Höbel
  • Achim AignerEmail author
Part of the Methods in Molecular Biology book series (MIMB, volume 623)


Since its discovery about 10 years ago, RNA interference (RNAi) has become an almost standard method for the knockdown of any target gene of interest. It is mediated by small interfering RNAs (siRNAs), which trigger a catalytic mechanism for mRNA degradation. Consequently, the delivery of intact siRNA is of critical importance for the induction of RNAi. Due to the physicochemical and biological properties of siRNAs, resulting in high instability and poor cellular uptake, siRNA modifications and pharmaceutical formulations have been used to enhance RNAi efficacy. This is particularly relevant for the in vivo delivery of siRNAs, which still poses a major hurdle for the experimental or therapeutic application of RNAi.

Polyethylenimines (PEIs) are water-soluble, linear, or branched synthetic polymers of variable length with protonable amino groups in every third position. We have shown that certain PEIs are able to form noncovalent complexes with siRNAs, which mediate their protection against nucleolytic degradation as well as enhance their cellular uptake and intracellular release. In this chapter, the preparation and use of PEI/siRNA complexes for various in vitro and in vivo applications are described. Examples for conducting gene targeting experiments and the analysis of knockdown efficacies are given.

Key words

RNA interference Small interfering RNA Polyethylenimine In vivo siRNA delivery Gene knockdown RNAi siRNA PEI 



The authors’ work was supported by grants from the German Cancer Aid (Deutsche Krebshilfe) and the German Research Foundation (Deutsche Forschungsgemeinschaft; AI 24/6-1 and Research Group 627 “Nanohale”).


  1. 1.
    Fire, A., Xu, S., Montgomery, M. K., Kostas, S. A., Driver, S. E., and Mello, C. C. (1998) Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature 391, 806–811.CrossRefPubMedGoogle Scholar
  2. 2.
    Aigner, A. (2007) Applications of RNA interference: current state and prospects for siRNA-based strategies in vivo. Appl. Microbiol. Biotechnol. 76, 9–21.CrossRefPubMedGoogle Scholar
  3. 3.
    Mittal, V. (2004) Improving the efficiency of RNA interference in mammals. Nat. Rev. Genet. 5, 355–365.CrossRefPubMedGoogle Scholar
  4. 4.
    de Fougerolles, A., Vornlocher, H. P., Maraganore, J., and Lieberman, J. (2007) Interfering with disease: a progress report on siRNA-based therapeutics. Nat. Rev. Drug Discov. 6, 443–453.CrossRefPubMedGoogle Scholar
  5. 5.
    Boussif, O., Lezoualc’h, F., Zanta, M. A., Mergny, M. D., Scherman, D., Demeneix, B., and Behr, J. P. (1995) A versatile vector for gene and oligonucleotide transfer into cells in culture and in vivo: polyethylenimine. Proc. Natl. Acad. Sci. U.S.A. 92, 7297–7301.CrossRefPubMedGoogle Scholar
  6. 6.
    Tang, M. X. and Szoka, F. C. (1997) The influence of polymer structure on the interactions of cationic polymers with DNA and morphology of the resulting complexes. Gene Ther. 4, 823–832.CrossRefPubMedGoogle Scholar
  7. 7.
    Godbey, W. T., Wu, K. K., and Mikos, A. G. (1999) Size matters: molecular weight affects the efficiency of poly(ethylenimine) as a gene delivery vehicle. J. Biomed. Mater. Res. 45, 268–275.CrossRefPubMedGoogle Scholar
  8. 8.
    Werth, S., Urban-Klein, B., Dai, L., Hobel, S., Grzelinski, M., Bakowsky, U., Czubayko, F., and Aigner, A. (2006) A low molecular weight fraction of polyethylenimine (PEI) displays increased transfection efficiency of DNA and siRNA in fresh or lyophilized complexes. J. Control. Release 112, 257–270.CrossRefPubMedGoogle Scholar
  9. 9.
    Urban-Klein, B., Werth, S., Abuharbeid, S., Czubayko, F., and Aigner, A. (2005) RNAi-mediated gene-targeting through systemic application of polyethylenimine (PEI)-complexed siRNA in vivo. Gene Ther. 12, 461–466.CrossRefPubMedGoogle Scholar
  10. 10.
    Grzelinski, M., Urban-Klein, B., Martens, T., Lamszus, K., Bakowsky, U., Hobel, S., Czubayko, F., and Aigner, A. (2006) RNA interference-mediated gene silencing of pleiotrophin through polyethylenimine-complexed small interfering RNAs in vivo exerts antitumoral effects in glioblastoma xenografts. Hum. Gene Ther. 17, 751–766.CrossRefPubMedGoogle Scholar
  11. 11.
    Hobel, S., Prinz, R., Malek, A., Urban-Klein, B., Sitterberg, J., Bakowsky, U., Czubayko, F., and Aigner, A. (2008) Polyethylenimine PEI F25-LMW allows the long-term storage of frozen complexes as fully active reagents in siRNA-mediated gene targeting and DNA delivery. Eur. J. Pharm. Biopharm. 70, 29–41.CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.Department of Pharmacology and ToxicologySchool of Medicine, Philipps-UniversityMarburgGermany

Personalised recommendations