title: Particle size and surface charge affect particle uptake by human dendritic cells in an in vitro model.
abstract: Current vaccine development includes optimization of antigen delivery to antigen presenting cells, such as dendritic cells (DC). Particulate systems have attracted increasing attention in the development of vaccine delivery systems. In the present study, we investigated DC uptake of model fluorescent polystyrene particles with a broad size range and variable surface properties. Localization of particles was investigated using confocal laser scanning microscopy and uptake was quantified by flow cytometry. Immature DC were generated from mononuclear cells isolated from human blood. The polystyrene particles interacted with the DC throughout the tested diameter range of 0.04-15 microm in a time- and concentration-dependent manner. The optimal particle diameter for fast and efficient acquisition by a substantial percentage of the DC was 0.5 microm and below. The surface of 1 and 0.1 microm polystyrene particles was covalently modified with different polyaminoacids/proteins, yielding particles with varying surface charge. Uptake of 1 microm particles was greatly enhanced when particles displayed a positive surface charge. In general, the present findings establish that particle diameters of 0.5 microm and below were optimal for DC uptake; however uptake of larger particles could be greatly enhanced by rendering the particle surface positive. Whether increased particle uptake is correlated with increased immune responses, remains to be established.
authors.affiliation: Department of Pharmaceutics, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark. cfo@dfuni.dk
authors.forename: Camilla
authors.initials: C
authors.lastname: Foged
authors.forename: Birger
authors.initials: B
authors.lastname: Brodin
authors.forename: Sven
authors.initials: S
authors.lastname: Frokjaer
authors.forename: Anne
authors.initials: A
authors.lastname: Sundblad
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003713:Dendritic Cells / Q000502:physiology*; D004563:Electrochemistry; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D006801:Humans; D049329:Nanostructures; D036103:Nanotechnology; D010316:Particle Size; D011137:Polystyrenes; D013499:Surface Properties
chemical_list: D005456:Fluorescent Dyes; D011137:Polystyrenes