title: Antibody-labeled liposomes for CT imaging of atherosclerotic plaques: in vitro investigation of an anti-ICAM antibody-labeled liposome containing iohexol for molecular imaging of atherosclerotic plaques via computed tomography.
abstract: We evaluated the specific binding of anti-intercellular adhesion molecule 1 (ICAM-1) conjugated liposomes (immunoliposomes, or ILs) to activated human coronary artery endothelial cells (HCAEC) with the purpose of designing a computed tomographic imaging agent for early detection of atherosclerotic plaques. Covalent attachment of anti-ICAM-1 monoclonal antibodies to pre-formed liposomes stabilized with polyethylene glycol yielded ILs, with a coupling efficiency of the ICAM-1 to the liposomes of 10% to 24%. The anti-ICAM-1-labeled ILs had an average diameter of 136 nm as determined by dynamic light-scattering and cryogenic electron microscopy. The ILs' encapsulation of 5-[N-acetyl-(2,3-dihydroxypropyl)-amino)-N, N'-bis(2,3-dihydroxypropyl)-2,4,6-triiodo-benzene-1,3-dicarboxamide (iohexol) was determined to be 18% to 19% by a dialysis technique coupled with ultraviolet detection of free iohexol. This encapsulation corresponded to 30 to 38 mg iodine per mL IL solution, and the ILs exhibited 91% to 98.5% iohexol retention at room temperature and under physiologic conditions. The specific binding of the ILs to cultured, activated HCAEC was measured using flow cytometry, enzyme-linked immunosorbent assays, and fluorescence microscopy. The immunosorbent assays demonstrated the specificity of binding of anti-ICAM-1 to ICAM-1 compared with control studies using nonspecific immunoglobulin G-labeled ILs. Flow cytometry and fluorescence microscopy experiments demonstrated the expression of ICAM-1 on the surface of activated HCAEC. Therefore, our iohexol-filled ILs demonstrated potential for implementation in computed tomographic angiography to noninvasively detect atherosclerotic plaques that are prone to rupture.
authors.affiliation: Department of Internal Medicine, Division of Cardiology, The University of Texas Health Science Center at Houston, Houston, Texas 77030, USA.
authors.forename: Delia
authors.initials: D
authors.lastname: Danila
authors.forename: Ranga
authors.initials: R
authors.lastname: Partha
authors.forename: Don B
authors.initials: DB
authors.lastname: Elrod
authors.forename: Melinda
authors.initials: M
authors.lastname: Lackey
authors.forename: S Ward
authors.initials: SW
authors.lastname: Casscells
authors.forename: Jodie L
authors.initials: JL
authors.lastname: Conyers
mesh_terms: D000911:Antibodies, Monoclonal / Q000378:metabolism*; D000918:Antibody Specificity; D002478:Cells, Cultured; D003287:Contrast Media / Q000378:metabolism*; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000276:immunology*; D003331:Coronary Vessels / Q000187:drug effects / Q000276:immunology*; D020285:Cryoelectron Microscopy; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000187:drug effects / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005022:Ethyldimethylaminopropyl Carbodiimide / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology*; D007472:Iohexol / Q000378:metabolism*; D008027:Light; D008081:Liposomes; D008856:Microscopy, Fluorescence; D053758:Nanoparticles; D012542:Scattering, Radiation; D013056:Spectrophotometry, Ultraviolet; D013388:Succinimides / Q000494:pharmacology; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D000911:Antibodies, Monoclonal; D003287:Contrast Media; D008081:Liposomes; D013388:Succinimides; D018799:Intercellular Adhesion Molecule-1; D007472:Iohexol; C035761:N-hydroxysulfosuccinimide; D005022:Ethyldimethylaminopropyl Carbodiimide