Objectives The aim of this study was to determine whether iron oxide particles targeted to oxidation-specific epitopes image atherosclerotic lesions. Background Oxidized low-density lipoprotein plays a major role in atherosclerotic plaque progression and destabilization. Prior studies indicate that gadolinium micelles labeled with oxidation-specific antibodies allow for in vivo detection of vulnerable plaques with magnetic resonance imaging (MRI). However, issues related to biotransformation/retention of gadolinium might limit clinical translation. Iron oxides are recognized as safe and effective contrast agents for MRI. Because the efficacy of passively targeted iron particles remains variable, it was hypothesized that iron particles targeted to oxidation-specific epitopes might increase the utility of this platform. Methods Lipid-coated ultra-small superparamagnetic iron particles (LUSPIOs) (<20 nm) and superparamagnetic iron particles (<40 nm) were conjugated with antibodies targeted to either malondialdehyde-lysine or oxidized phospholipid epitopes. All formulations were characterized, and their in vivo efficacy evaluated in apolipoprotein E deficient mice 24 h after bolus administration of a 3.9-mg Fe/kg dose with MRI. In vivo imaging data were correlated with the presence of oxidation-specific epitopes with immunohistochemistry. Results MRI of atherosclerotic lesions, as manifested by signal loss, was observed after administration of targeted LUSPIOs. Immunohistochemistry confirmed the presence of malondialdehyde-epitopes and iron particles. Limited signal attenuation was observed for untargeted LUSPIOs. Additionally, no significant arterial wall uptake was observed for targeted or untargeted lipid-coated superparamagnetic iron oxide particles, due to their limited ability to penetrate the vessel wall. Conclusions This study demonstrates that LUSPIOs targeted to oxidation-specific epitopes image atherosclerotic lesions and suggests a clinically translatable platform for the detection of atherosclerotic plaque.

Objectives To evaluate the in vivo magnetic resonance (MR) imaging efficacy of manganese (Mn(II)) molecular imaging probes targeted to oxidation-specific epitopes (OSE). Background OSE are critical in the initiation, progression and de-stabilization of atherosclerotic plaques. Gadolinium (Gd(III)) based MR imaging agents can be associated with systemic toxicity. Mn is an endogenous, bio-compatible, paramagnetic metal ion that has poor MR efficacy when chelated, but strong efficacy when released within cells. Methods Multimodal Mn-micelles were generated to contain rhodamine for confocal microscopy and conjugated with either the murine monoclonal IgG antibody MDA2 targeted to malondialdehyde (MDA)-lysine epitopes or the human single-chain Fv antibody fragment IK17 targeted to MDA-like epitopes (‘targeted micelles”). Micelle formulations were characterized in vitro and in vivo and their MR efficacy (9.4 Tesla) evaluated in apoE−/− and LDLR−/− mice (0.05 mmol Mn/Kg dose) (total of 120 mice for all experiments). In vivo competitive inhibition studies were performed to evaluate target specificity. Untargeted, MDA2-Gd and IK17-Gd micelles (0.075 mmol Gd/Kg) were included as controls. Results In vitro studies demonstrated that targeted Mn-micelles accumulate in macrophages when pre-exposed to MDA-LDL with ~10X increase in longitudinal relativity. Following intravenous injection, strong MR signal enhancement was observed 48–72 hours after administration of targeted Mn-micelles, with co-localization within intraplaque macrophages. Co-injection of free MDA2 with the MDA2-Mn micelles resulted in full suppression of MR signal in the arterial wall confirming target specificity. Similar MR efficacy was noted in apoE−/− and LDLR−/− mice with aortic atherosclerosis. No significant differences in MR efficacy were noted between targeted Mn and Gd micelles. Conclusions This study demonstrates that bio-compatible multimodal Mn-based molecular imaging probes detect OSE within atherosclerotic plaques and may facilitate clinical translation of non-invasive imaging of human atherosclerosis.

Smartphone technology has spread rapidly around the globe. According to a report released by the Korea Information Society Development Institute, about 95% of Koreans aged more than 30 years old owned smartphones. Recently, blood pressure (BP) measurement using a photoplethysmography-based smartphone algorithm paired with the smartwatch is continuously evolving. In this document, the Korean Society of Hypertension intends to remark the current results of smartphone / smartwatch-based BP measurement and recommend optimal BP measurement methods using a smartphone device. We aim to increase the likelihood of success in implementing these new technologies into improved hypertension awareness, diagnosis, and control.