title: Optimized polyethylenimine (PEI)-based nanoparticles for siRNA delivery, analyzed in vitro and in an ex vivo tumor tissue slice culture model.
abstract: The non-viral delivery of small RNA molecules like siRNAs still poses a major bottleneck for their successful application in vivo. This is particularly true with regard to crossing physiological barriers upon systemic administration. We have previously established polyethylenimine (PEI)-based complexes for therapeutic RNA formulation. These nanoplexes mediate full RNA protection against nucleolytic degradation, delivery to target tissues as well as cellular uptake, intracellular release and therapeutic efficacy in preclinical in vivo models. We herein present data on different polyplex modifications for the defined improvement of physicochemical and biological nanoparticle properties and for targeted delivery. (i) By non-covalent modifications of PEI polyplexes with phospholipid liposomes, ternary complexes ("lipopolyplexes") are obtained that combine the favorable features of PEI and lipid systems. Decreased cytotoxicity and highly efficient delivery of siRNA is achieved. Some lipopolyplexes also allow prolonged storage, thus providing formulations with higher stability. (ii) Novel tyrosine modifications of low molecular weight PEI offer further improvement of stability, biocompatibility, and knockdown efficacy of resulting nanoparticles. (iii) For ligand-mediated uptake, the shielding of surface charges is a critical requirement. This is achieved by PEI grafting with polyethylene glycol (PEG), prior to covalent coupling of anti-HER1 antibodies (Erbitux®) as ligand for targeted delivery and uptake. Beyond tumor cell culture, analyses are extended towards tumor slice cultures from tumor xenograft tissues which reflect more realistically the in vivo situation. The determination of siRNA-mediated knockdown of endogenous target genes, i.e., the oncogenic survival factor survivin and the oncogenic receptor tyrosine kinase HER2, reveals nanoparticle penetration and biological efficacy also under intact tissue and stroma conditions.
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Clinical Pharmacology, Leipzig University, Haertelstrasse 16 - 18, D-04107, Leipzig, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ewe
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Clinical Pharmacology, Leipzig University, Haertelstrasse 16 - 18, D-04107, Leipzig, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Höbel
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Leipzig University, Leipzig, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Heine
authors.affiliation: Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany.
authors.forename: Lea
authors.initials: L
authors.lastname: Merz
authors.affiliation: Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Kallendrusch
authors.affiliation: Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Bechmann
authors.affiliation: Institute of Anatomy, Medical Faculty, Leipzig University, Leipzig, Germany.|Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany.
authors.forename: Felicitas
authors.initials: F
authors.lastname: Merz
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Leipzig University, Leipzig, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Franke
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Clinical Pharmacology, Leipzig University, Haertelstrasse 16 - 18, D-04107, Leipzig, Germany. achim.aigner@medizin.uni-leipzig.de.
authors.forename: Achim
authors.initials: A
authors.lastname: Aigner
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D006801:Humans; D008055:Lipids / Q000008:administration & dosage / Q000737:chemistry; D008156:Luciferases / Q000235:genetics; D008819:Mice, Nude; D053758:Nanoparticles / Q000008:administration & dosage* / Q000737:chemistry; D011094:Polyethyleneimine / Q000008:administration & dosage* / Q000737:chemistry; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D008055:Lipids; D034741:RNA, Small Interfering; D011094:Polyethyleneimine; D008156:Luciferases
keywords: Knockdown; Lipopolyplexes; PEG-PEI-Erbitux conjugates; PEI/siRNA complexes; Polyethylenimine; RNAi; Tissue slices; siRNA