Novel molecular imaging of atherosclerosis with gallium-68-labeled apolipoprotein A-I mimetic peptide and positron emission tomography

High-density lipoprotein (HDL) plays a major role in reverse cholesterol transport. Many researchers have been working to enhance the biochemical function of HDL for use in therapy. Although HDL therapy using injections of apolipoprotein (apo)-A-I mimetics, apo A-IMilano or full-length apo A-I is dramatically effective, it is still unclear whether apo A-I or apo A-I mimetics actually enter atherosclerotic plaque and remove cholesterol from the lipid burden. We synthesized a novel 24-amino acid apo A-I mimetic peptide (known as Fukuoka University apo A-I mimetic peptide (FAMP)) that potently removes cholesterol via specific adenosine 5'-triphosphate (ATP)-binding cassette transporter A1. We then investigated the potential of FAMP to image developing plaque lesions in vivo. FAMP was modified with 1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA) and radiolabeled with gallium-68 (68Ga) for noninvasive positron emission tomography (PET) in an animal model (familial hypercholesterolemic myocardial infarction-prone rabbits: Watanabe heritable hyperlipidemic (WHHL-MI)) with atherosclerotic lesions. The 68Ga-DOTA-FAMP was dramatically taken up by atherosclerotic tissues in the blood vessels and aorta of WHHL-MI rabbits, but not the control rabbits. An apo A-I mimetic peptide with 68Ga-DOTA is a promising candidate diagnostic tracer for PET imaging of the atherosclerotic lipid burden and may contribute to the development of a tool for the diagnosis of plaque with PET. (author)