title: Development and characterization of an antibody-labeled super-paramagnetic iron oxide contrast agent targeting prostate cancer cells for magnetic resonance imaging.
abstract: In this study we developed, characterized and validated in vitro a functional superparagmagnetic iron-oxide based magnetic resonance contrast agent by conjugating a commercially available iron oxide nanoparticle, Molday ION Rhodamine-B Carboxyl (MIRB), with a deimmunized mouse monoclonal antibody (muJ591) targeting prostate-specific membrane antigen (PSMA). This functional contrast agent is intended for the specific and non-invasive detection of prostate cancer cells that are PSMA positive, a marker implicated in prostate tumor progression and metastasis. The two-step carbodiimide reaction used to conjugate the antibody to the nanoparticle was efficient and we obtained an elemental iron content of 1958 ± 611 per antibody. Immunofluorescence microscopy and flow cytometry showed that the conjugated muJ591:MIRB complex specifically binds to PSMA-positive (LNCaP) cells. The muJ591:MIRB complex reduced cell adhesion and cell proliferation on LNCaP cells and caused apoptosis as tested by Annexin V assay, suggesting anti-tumorigenic characteristics. Measurements of the T2 relaxation time of the muJ591:MIRB complex using a 400 MHz Innova NMR and a multi-echo spin-echo sequence on a 3T MRI (Achieva, Philips) showed a significant T2 relaxation time reduction for the muJ591:MIRB complex, with a reduced T2 relaxation time as a function of the iron concentration. PSMA-positive cells treated with muJ591:MIRB showed a significantly shorter T2 relaxation time as obtained using a 3T MRI scanner. The reduction in T2 relaxation time for muJ591:MIRB, combined with its specificity against PSMA+LNCaP cells, suggest its potential as a biologically-specific MR contrast agent.
authors.affiliation: Thunder Bay Regional Research Institute, Ontario, Canada; Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada.
authors.forename: David
authors.initials: D
authors.lastname: Bates
authors.affiliation: Thunder Bay Regional Research Institute, Ontario, Canada.
authors.forename: Suraj
authors.initials: S
authors.lastname: Abraham
authors.affiliation: Thunder Bay Regional Research Institute, Ontario, Canada; Department of Chemistry, Lakehead University, Thunder Bay, Ontario, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Campbell
authors.affiliation: Thunder Bay Regional Research Institute, Ontario, Canada; Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Zehbe
authors.affiliation: Thunder Bay Regional Research Institute, Ontario, Canada; Department of Physics, Lakehead University, Thunder Bay, Ontario, Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: Curiel
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000276:immunology; D000954:Antigens, Surface / Q000276:immunology; D045744:Cell Line, Tumor; D003287:Contrast Media / Q000737:chemistry; D018450:Disease Progression; D005290:Ferric Compounds / Q000737:chemistry*; D043425:Glutamate Carboxypeptidase II / Q000276:immunology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D009362:Neoplasm Metastasis; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D012235:Rhodamines / Q000737:chemistry; D013194:Staining and Labeling
chemical_list: D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D003287:Contrast Media; D005290:Ferric Compounds; D012235:Rhodamines; C000499:ferric oxide; C473848:FOLH1 protein, human; D043425:Glutamate Carboxypeptidase II; C029773:rhodamine B