title: Size matters for in vitro gene delivery: investigating the relationships among complexation protocol, transfection medium, size and sedimentation.
abstract: Although branched and linear polyethylenimines (bPEIs and lPEIs) are gold standard transfectants, a systematic analysis of the effects of the preparation protocol of polyplexes and the composition of the transfection medium on their physicochemical behaviour and effectiveness in vitro have been much neglected, undermining in some way the identification of precise structure-function relationships. This work aimed to address these issues. bPEI/DNA and lPEI/DNA, prepared using two different modes of addition of reagents, gave rise to polyplexes with exactly the same chemical composition but differing in dimensions. Upon dilution in serum-free medium, the size of any kind of polyplex promptly rose over time while remained invariably stable in complete DMEM. Of note, the bigger the dimension of polyplexes (in the nano- to micrometer range), the greater their efficiency in vitro. Besides, centrifugal sedimentation of polyplexes displaying different dimensions to speed up and enhance their settling onto cells boosted transfection efficiencies. Conversely, transgene expression was significantly blunted in cells held upside-down and transfected, definitively pointing out the impact of gravitational sedimentation of polyplexes on their transfection efficiency. Overall, much more attention must be paid to the actual polyplex size that relies on the complexation conditions and the transfection medium.
authors.affiliation: Research Unit Milano Politecnico, National Interuniversity Consortium of Materials Science and Technology - INSTM, Via Mancinelli 7, Milan 20131, Italy.|Laboratory for Biomaterials and Bioengineering, CRC-I, Department of Mining, Metallurgical and Materials Engineering &CHU de Quebec Research Centre, Laval University, 10 rue de l'Espinay, Quebec City (QC) G1L 3L5, Canada.
authors.forename: Daniele
authors.initials: D
authors.lastname: Pezzoli
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via Mancinelli 7, Milan 20131, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Giupponi
authors.affiliation: Laboratory for Biomaterials and Bioengineering, CRC-I, Department of Mining, Metallurgical and Materials Engineering &CHU de Quebec Research Centre, Laval University, 10 rue de l'Espinay, Quebec City (QC) G1L 3L5, Canada.
authors.forename: Diego
authors.initials: D
authors.lastname: Mantovani
authors.affiliation: Research Unit Milano Politecnico, National Interuniversity Consortium of Materials Science and Technology - INSTM, Via Mancinelli 7, Milan 20131, Italy.|Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Via Mancinelli 7, Milan 20131, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Candiani
mesh_terms: D016895:Culture Media, Serum-Free / Q000737:chemistry / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D011094:Polyethyleneimine / Q000737:chemistry / Q000494:pharmacology; D014162:Transfection / Q000379:methods*
chemical_list: D016895:Culture Media, Serum-Free; D011094:Polyethyleneimine; D004247:DNA