title: Quantification of the expression level of integrin receptor alpha(v)beta3 in cell lines and MR imaging with antibody-coated iron oxide particles.
abstract: Targeted imaging requires site-specific accumulation of a contrast agent (CA), and the properties of that agent must be selected according to the abundance of the target to obtain a signal above the detection limit of the instrument. However, numerical estimates of receptors per cell are rarely found in the literature. Integrin receptors would be particularly promising targets because of their accessibility from the blood stream and expression on activated neovascular endothelial cells. We systematically estimated the number of integrin receptors of cell lines and primary cells by flow cytometry analysis. Since integrin receptors are heterodimeric molecules, and alpha(v) forms complexes with various beta subunits, the numbers of alpha(v) and beta(3) subunits are therefore dissimilar. The observed values are 3 . 10(3)-1.4 . 10(4)/cell for alpha(v), and 5.3 . 10(2)-1.1 . 10(4)/cell for beta(3). Despite the low number of exposed receptors, we show that up to single-cell MR visualization can be achieved with the use of iron oxide beads complexed with antibodies as CAs.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Turin, Turin, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Benedetto
authors.forename: Roberta
authors.initials: R
authors.lastname: Pulito
authors.forename: Simonetta Geninatti
authors.initials: SG
authors.lastname: Crich
authors.forename: Guido
authors.initials: G
authors.lastname: Tarone
authors.forename: Silvio
authors.initials: S
authors.lastname: Aime
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Silengo
authors.forename: Jörg
authors.initials: J
authors.lastname: Hamm
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001710:Biotin / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D005434:Flow Cytometry; D005909:Glioblastoma / Q000378:metabolism; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D007501:Iron; D007948:Leukemia, Monocytic, Acute / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D010087:Oxides; D019030:Receptors, Vitronectin / Q000378:metabolism*; D019809:Streptavidin / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D003287:Contrast Media; D003911:Dextrans; D039302:Integrin alphaVbeta3; D058185:Magnetite Nanoparticles; D010087:Oxides; D019030:Receptors, Vitronectin; D001710:Biotin; D019809:Streptavidin; D007501:Iron; C065507:ferumoxides; D052203:Ferrosoferric Oxide