title: Differential uptake of functionalized polystyrene nanoparticles by human macrophages and a monocytic cell line.
abstract: Tumor cell lines are often used as models for the study of nanoparticle-cell interactions. Here we demonstrate that carboxy (PS-COOH) and amino functionalized (PS-NH2) polystyrene nanoparticles of ∼100 nm in diameter are internalized by human macrophages, by undifferentiated and by PMA-differentiated monocytic THP-1 cells via diverse mechanisms. The uptake mechanisms also differed for all cell types and particles when analyzed either in buffer or in medium containing human serum. Macrophages internalized ∼4 times more PS-COOH than THP-1 cells, when analyzed in serum-containing medium. By contrast, in either medium, THP-1 cells internalized PS-NH2 more rapidly than macrophages. Using pharmacological and antisense in vitro knockdown approaches, we showed that, in the presence of serum, the specific interaction between the CD64 receptor and the particles determines the macrophage uptake of particles by phagocytosis, whereas particle internalization in THP-1 cells occurred via dynamin II-dependent endocytosis. PMA-differentiated THP-1 cells differed in their uptake mechanism from macrophages and undifferentiated THP-1 cells by internalizing the particles via macropinocytosis. In line with our in vitro data, more intravenously applied PS-COOH particles accumulated in the liver, where macrophages of the reticuloendothelial system reside. By contrast, PS-NH2 particles were preferentially targeted to tumor xenografts grown on the chorioallantoic membrane of fertilized chicken eggs. Our data show that the amount of internalized nanoparticles, the uptake kinetics, and its mechanism may differ considerably between primary cells and a related tumor cell line, whether differentiated or not, and that particle uptake by these cells is critically dependent on particle opsonization by serum proteins.
authors.affiliation: Institute of Pharmacology of Natural Products & Clinical Pharmacology, Ulm University, Ulm, Germany.
authors.forename: Oleg
authors.initials: O
authors.lastname: Lunov
authors.forename: Tatiana
authors.initials: T
authors.lastname: Syrovets
authors.forename: Cornelia
authors.initials: C
authors.lastname: Loos
authors.forename: Johanna
authors.initials: J
authors.lastname: Beil
authors.forename: Michael
authors.initials: M
authors.lastname: Delacher
authors.forename: Kyrylo
authors.initials: K
authors.lastname: Tron
authors.forename: G Ulrich
authors.initials: GU
authors.lastname: Nienhaus
authors.forename: Anna
authors.initials: A
authors.lastname: Musyanovych
authors.forename: Volker
authors.initials: V
authors.lastname: Mailänder
authors.forename: Katharina
authors.initials: K
authors.lastname: Landfester
authors.forename: Thomas
authors.initials: T
authors.lastname: Simmet
mesh_terms: D002460:Cell Line; D006801:Humans; D008264:Macrophages / Q000737:chemistry* / Q000378:metabolism* / Q000502:physiology*; D009000:Monocytes / Q000737:chemistry / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry*; D010587:Phagocytosis / Q000502:physiology*; D011137:Polystyrenes / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D011137:Polystyrenes