title: Tumor tissue slice cultures as a platform for analyzing tissue-penetration and biological activities of nanoparticles.
abstract: The success of therapeutic nanoparticles depends, among others, on their ability to penetrate a tissue for actually reaching the target cells, and their efficient cellular uptake in the context of intact tissue and stroma. Various nanoparticle modifications have been implemented for altering physicochemical and biological properties. Their analysis, however, so far mainly relies on cell culture experiments which only poorly reflect the in vivo situation, or is based on in vivo experiments that are often complicated by whole-body pharmacokinetics and are rather tedious especially when analyzing larger nanoparticle sets. For the more precise analysis of nanoparticle properties at their desired site of action, efficient ex vivo systems closely mimicking in vivo tissue properties are needed. In this paper, we describe the setup of organotypic tumor tissue slice cultures for the analysis of tissue-penetrating properties and biological activities of nanoparticles. As a model system, we employ 350μm thick slice cultures from different tumor xenograft tissues, and analyze modified or non-modified polyethylenimine (PEI) complexes as well as their lipopolyplex derivatives for siRNA delivery. The described conditions for tissue slice preparation and culture ensure excellent tissue preservation for at least 14days, thus allowing for prolonged experimentation and analysis. When using fluorescently labeled siRNA for complex visualization, fluorescence microscopy of cryo-sectioned tissue slices reveals different degrees of nanoparticle tissue penetration, dependent on their surface charge. More importantly, the determination of siRNA-mediated knockdown efficacies of an endogenous target gene, the oncogenic survival factor Survivin, reveals the possibility to accurately assess biological nanoparticle activities in situ, i.e. in living cells in their original environment. Taken together, we establish tumor (xenograft) tissue slices for the accurate and facile ex vivo assessment of important biological nanoparticle properties. Beyond the quantitative analysis of nanoparticle tissue-penetration, the excellent tissue preservation and cell viability also allows for the evaluation of biological activities.
authors.affiliation: Institute of Anatomy, Medical Faculty, University of Leipzig, Germany.
authors.forename: Lea
authors.initials: L
authors.lastname: Merz
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Clinical Pharmacology, Medical Faculty, University of Leipzig, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Höbel
authors.affiliation: Institute of Anatomy, Medical Faculty, University of Leipzig, Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Kallendrusch
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Clinical Pharmacology, Medical Faculty, University of Leipzig, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ewe
authors.affiliation: Institute of Anatomy, Medical Faculty, University of Leipzig, Germany.
authors.forename: Ingo
authors.initials: I
authors.lastname: Bechmann
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Medical Faculty, University of Leipzig, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Franke
authors.affiliation: Institute of Anatomy, Medical Faculty, University of Leipzig, Germany.
authors.forename: Felicitas
authors.initials: F
authors.lastname: Merz
authors.affiliation: Rudolf-Boehm-Institute for Pharmacology and Toxicology, Clinical Pharmacology, Medical Faculty, University of Leipzig, Germany. Electronic address: achim.aigner@medizin.uni-leipzig.de.
authors.forename: Achim
authors.initials: A
authors.lastname: Aigner
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D064593:Heterografts; D006801:Humans; D051379:Mice; D053758:Nanoparticles; D009369:Neoplasms / Q000378:metabolism*; D010599:Pharmacokinetics; D011094:Polyethyleneimine / Q000737:chemistry
chemical_list: D011094:Polyethyleneimine
keywords: Lipopolyplexes; PEI complexes; PEI/siRNA gene knockdown; Polyethylenimine; Polymeric nanoparticles; Tissue slices; Tumor xenografts