title: Two-step in vivo tumor targeting by biotin-conjugated antibodies and superparamagnetic nanoparticles assessed by magnetic resonance imaging at 1.5 T.
abstract: OBJECTIVE
  The purpose of this study was to assess two-step in vivo tumor targeting by specific biotin-conjugated antibodies and ultrasmall superparamagnetic iron oxide (USPIO)-anti-biotin nanoparticles as contrast agents for magnetic resonance imaging (MRI) at 1.5 T.
  
  
  METHODS
  D430B human lymphoma cells, expressing the CD70 surface antigen, were injected either s.c. or i.v. to induce pseudo-metastases in NOD/SCID mice. Thirty micrograms of biotin-conjugated monoclonal anti-CD70 was injected i.v., followed 4 h later by 8 micromol Fe/Kg USPIO-anti-biotin. After 24 h, MRI was performed on T2* and b-FFE sequences. Signal intensity (SI) was calculated before and after USPIO-anti-biotin administration.
  
  
  RESULTS
  Subcutaneous xenografts showed a dishomogeneous 30% decrease in SI on T2* with anti-CD70 + USPIO-anti-biotin treatment. Pseudo-metastatic xenografts showed a slight reduction in SI on T2*, but a 60% decrease in SI on b-FFE-weighted sequences. Prussian blue staining confirmed the presence of iron nanoparticles in the excised tumors.
  
  
  CONCLUSIONS
  MRI at 1.5 T can detect tumors by a two-step in vivo biotin-based protocol, which may allow the targeting of any cell surface antigen.
authors.affiliation: Department of Diagnostic Imaging, IST, National Cancer Institute, Largo Rosanna Benzi 10, 16132, Genoa, Italy.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Baio
authors.forename: Marina
authors.initials: M
authors.lastname: Fabbi
authors.forename: Sandra
authors.initials: S
authors.lastname: Salvi
authors.forename: Daniela
authors.initials: D
authors.lastname: de Totero
authors.forename: Mauro
authors.initials: M
authors.lastname: Truini
authors.forename: Silvano
authors.initials: S
authors.lastname: Ferrini
authors.forename: Carlo Emanuele
authors.initials: CE
authors.lastname: Neumaier
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D000912:Antibodies, Neoplasm / Q000276:immunology*; D001710:Biotin / Q000378:metabolism*; D053282:CD27 Ligand / Q000378:metabolism; D045744:Cell Line, Tumor; D003911:Dextrans / Q000378:metabolism*; D052203:Ferrosoferric Oxide / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D018796:Immunoconjugates / Q000276:immunology*; D008223:Lymphoma / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D053758:Nanoparticles / Q000737:chemistry*; D009362:Neoplasm Metastasis; D009369:Neoplasms / Q000276:immunology* / Q000473:pathology; D013194:Staining and Labeling; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D053282:CD27 Ligand; C505771:CD70 protein, human; D003911:Dextrans; D018796:Immunoconjugates; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10; D001710:Biotin; D052203:Ferrosoferric Oxide