Hiroyuki Ikeda1, Akira Ishii2, Kohei Sano3, Hideo Chihara2, Daisuke Arai2, Yu Abekura2, Hidehisa Nishi2, Masahiro Ono4, Hideo Saji4, Susumu Miyamoto2. 1. Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan. Electronic address: rocky@kuhp.kyoto-u.ac.jp. 2. Department of Neurosurgery, Kyoto University Graduate School of Medicine, Kyoto, Japan. 3. Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan; Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe, Japan. Electronic address: ksano@kobepharma-u.ac.jp. 4. Department of Patho-Functional Bioanalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
Abstract
BACKGROUND AND AIMS: Macrophages are key factors in the formation of unstable atherosclerotic plaques, which may be identified through macrophage imaging. We tested whether activatable fluorescence probes of iron oxide nanoparticles (IONPs) conjugated with indocyanine green (ICG) (IONP-ICG), consisting of biocompatible reagents, can visualize macrophages present in atherosclerotic plaques. METHODS: IONP-based probes conjugated with different numbers of ICG molecules were synthesized. Six-week-old spontaneously hyperlipidemic (SHL) mice were fed either a Western or normal diet for 14 weeks, and were intravenously injected with IONP-ICG (55.8 mg Fe/kg). Aortas were harvested 48 h later, and aortas containing atherosclerotic plaques were imaged. RESULTS: Phantom imaging studies using IONP-ICG solution demonstrated that the addition of surfactants to IONP-ICG solutions yielded fluorescence activation. Incubation of macrophages with IONP-ICG led to internalization of IONP-ICG and near infrared fluorescence (NIRF) activation. In NIRF imaging studies, intense fluorescence signals were clearly visible primarily at the margins of atherosclerotic plaques, and relatively weak signals were evident inside the plaques, demonstrating the feasibility of detection of NIRF signals at atherosclerotic plaques. In the quantitative evaluation of NIRF, administration of a probe conjugated with more ICG molecules led to a significant increase in the NIRF signal, indicating that probes with greater numbers of ICG molecules are effective for sensitive NIRF detection. SHL mice given a low-cholesterol normal diet showed a significantly lower NIRF signal compared with mice given the Western diet. Histologically, NIRF signals in atherosclerotic plaques strongly correlated with the location of macrophages, suggesting the possibility of NIRF macrophage imaging using IONP-ICG. CONCLUSIONS: Localization of macrophages in atherosclerotic plaques may be achieved using the activatable NIRF probe, IONP-ICG.
BACKGROUND AND AIMS: Macrophages are key factors in the formation of unstable atherosclerotic plaques, which may be identified through macrophage imaging. We tested whether activatable fluorescence probes of iron oxide nanoparticles (IONPs) conjugated with indocyanine green (ICG) (IONP-ICG), consisting of biocompatible reagents, can visualize macrophages present in atherosclerotic plaques. METHODS: IONP-based probes conjugated with different numbers of ICG molecules were synthesized. Six-week-old spontaneously hyperlipidemic (SHL) mice were fed either a Western or normal diet for 14 weeks, and were intravenously injected with IONP-ICG (55.8 mg Fe/kg). Aortas were harvested 48 h later, and aortas containing atherosclerotic plaques were imaged. RESULTS: Phantom imaging studies using IONP-ICG solution demonstrated that the addition of surfactants to IONP-ICG solutions yielded fluorescence activation. Incubation of macrophages with IONP-ICG led to internalization of IONP-ICG and near infrared fluorescence (NIRF) activation. In NIRF imaging studies, intense fluorescence signals were clearly visible primarily at the margins of atherosclerotic plaques, and relatively weak signals were evident inside the plaques, demonstrating the feasibility of detection of NIRF signals at atherosclerotic plaques. In the quantitative evaluation of NIRF, administration of a probe conjugated with more ICG molecules led to a significant increase in the NIRF signal, indicating that probes with greater numbers of ICG molecules are effective for sensitive NIRF detection. SHL mice given a low-cholesterol normal diet showed a significantly lower NIRF signal compared with mice given the Western diet. Histologically, NIRF signals in atherosclerotic plaques strongly correlated with the location of macrophages, suggesting the possibility of NIRF macrophage imaging using IONP-ICG. CONCLUSIONS: Localization of macrophages in atherosclerotic plaques may be achieved using the activatable NIRF probe, IONP-ICG.
Authors: Marina S Dukhinova; Artur Y Prilepskii; Alexander A Shtil; Vladimir V Vinogradov Journal: Nanomaterials (Basel) Date: 2019-11-16 Impact factor: 5.076
Authors: Xiaotian Wu; Amy Daniel Ulumben; Steven Long; Wataru Katagiri; Moses Q Wilks; Hushan Yuan; Brian Cortese; Chengeng Yang; Satoshi Kashiwagi; Hak Soo Choi; Marc D Normandin; Georges El Fakhri; Raiyan T Zaman Journal: Biomolecules Date: 2021-11-24