title: Comparison of synthetic high density lipoprotein (HDL) contrast agents for MR imaging of atherosclerosis.
abstract: Determining arterial macrophage expression is an important goal in the molecular imaging of atherosclerosis. Here, we compare the efficacy of two synthetic, high density lipoprotein (HDL) based contrast agents for magnetic resonance imaging (MRI) of macrophage burden. Each form of HDL was labeled with gadolinium and rhodamine to allow MRI and fluorescence microscopy. Either the 37 or 18 amino acid peptide replaced the apolipoprotein A-I in these agents, which were termed 37pA-Gd or 18A-Gd. The diameters of 37pA-Gd and 18A-Gd are 7.6 and 8.0 nm, respectively, while the longitudinal relaxivities are 9.8 and 10.0 (mM s)(-1). 37pA has better lipid binding properties. In vitro tests with J774A.1 macrophages proved the particles possessed the functionality of HDL by eliciting cholesterol efflux and were taken up in a receptor-like fashion by the cells. Both agents produced enhancements in atherosclerotic plaques of apolipoprotein E knockout mice of approximately 90% (n = 7 per agent) and are macrophage specific as evidenced by confocal microscopy on aortic sections. The half-lives of 37pA-Gd and 18A-Gd are 2.6 and 2.1 h, respectively. Despite the more favorable lipid interactions of 37pA, both agents gave similar, excellent contrast for the detection of atherosclerotic macrophages using MRI.
authors.affiliation: Translational and Molecular Imaging Institute, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Cormode
authors.forename: Rohith
authors.initials: R
authors.lastname: Chandrasekar
authors.forename: Amanda
authors.initials: A
authors.lastname: Delshad
authors.forename: Karen C
authors.initials: KC
authors.lastname: Briley-Saebo
authors.forename: Claudia
authors.initials: C
authors.lastname: Calcagno
authors.forename: Alessandra
authors.initials: A
authors.lastname: Barazza
authors.forename: Willem J M
authors.initials: WJ
authors.lastname: Mulder
authors.forename: Edward A
authors.initials: EA
authors.lastname: Fisher
authors.forename: Zahi A
authors.initials: ZA
authors.lastname: Fayad
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D050197:Atherosclerosis / Q000175:diagnosis*; D001692:Biological Transport; D002460:Cell Line; D002784:Cholesterol / Q000378:metabolism; D003287:Contrast Media / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics; D008075:Lipoproteins, HDL / Q000737:chemistry*; D008264:Macrophages / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics; D051381:Rats
chemical_list: D003287:Contrast Media; D008075:Lipoproteins, HDL; D010455:Peptides; C080383:peptide 18A; D002784:Cholesterol