We investigated the ability of targeted immunomicelles to detect and assess macrophages in atherosclerotic plaque using MRI in vivo. There is a large clinical need for a noninvasive tool to assess atherosclerosis from a molecular and cellular standpoint. Macrophages play a central role in atherosclerosis and are associated with plaques vulnerable to rupture. Therefore, macrophage scavenger receptor (MSR) was chosen as a target for molecular MRI. MSR-targeted immunomicelles, micelles, and gadolinium-diethyltriaminepentaacetic acid (DTPA) were tested in ApoE؊/؊ and WT mice by using in vivo MRI. Confocal laser-scanning microscopy colocalization, macrophage immunostaining and MRI correlation, competitive inhibition, and various other analyses were performed. In vivo MRI revealed that at 24 h postinjection, immunomicelles provided a 79% increase in signal intensity of atherosclerotic aortas in ApoE؊/؊ mice compared with only 34% using untargeted micelles and no enhancement using gadolinium-DTPA. Confocal laser-scanning microscopy revealed colocalization between fluorescent immunomicelles and macrophages in plaques. There was a strong correlation between macrophage content in atherosclerotic plaques and the matched in vivo MRI results as measured by the percent normalized enhancement ratio. Monoclonal antibodies to MSR were able to significantly hinder immunomicelles from providing contrast enhancement of atherosclerotic vessels in vivo. Immunomicelles provided excellent validated in vivo enhancement of atherosclerotic plaques. The enhancement seen is related to the macrophage content of the atherosclerotic vessel areas imaged. Immunomicelles may aid in the detection of high macrophage content associated with plaques vulnerable to rupture. macrophage scavenger receptor ͉ molecular imaging ͉ vulnerable plaque ͉ immunomicelles ͉ gadolinium

A new contrast agent for MRI based on recombinant HDL-like nanoparticles has been prepared. It shows a great potential as a contrast agent for atherosclerotic plaques in a relative short time (24 h post-injection) as it is selective for the plaques and is an endogenous molecule. It also can distinguish between different types of plaques as the enhancement obtained is different, depending on plaque composition.

The need for more specific and selective contrast agents for magnetic resonance imaging motivated us to prepare a new nanoparticle agent based on high-density lipoproteins (HDL). This second generation contrast agent can be prepared in three different ways. The HDL nanoparticles (rHDL) were fully characterized by FPLC and gel electrophoresis. The flexibility of the platform also allows us to incorporate optical probes into rHDL for localization ex vivo by confocal fluorescence microscopy. The contrast-agent-containing nanoparticles were injected into mice that develop atherosclerotic lesions. Magnetic resonance imaging of the animals showed clear enhancement of the atherosclerotic plaques.

Pegylated, fluorescent, and paramagnetic micelles were developed. The micelles were conjugated with macrophage scavenger receptor (MSR)-specific antibodies. The abdominal aortas of atherosclerotic apoE-KO mice were imaged with T 1 -weighted high-resolution MRI before and 24 h after intravenous administration of the contrast agent (CA). Pronounced signal enhancement (SE) (up to 200%) was observed for apolipoprotein E knockout (apoE-KO) mice that were injected with MSRtargeted micelles, while the aortic vessel wall of mice injected with nontargeted micelles showed little SE. To allow fluorescence microscopy and optical imaging of the excised aorta, the micelles were made fluorescent by incorporating either a quantum dot (QD) in the micelle corona or rhodamine lipids in the micelle. Ultraviolet (UV) illumination of the aorta allowed the identification of regions with high macrophage content, while MSR-targeted rhodamine micelles could be detected with fluorescence microscopy and were found to be associated with macrophages. In conclusion, this study demonstrates that macrophages in apoE-KO mice can be effectively and specifically detected by molecular MRI and optical methods upon administration of a pegylated micellar CA. Magn Reson Med 58:1164 -1170, 2007.

The ability to specifically image macrophages may enable improved detection and characterization of atherosclerosis. In this study we evaluated the in vitro uptake of gadolinium (Gd)-containing immunomicelles (micelles linked to macrophagespecific antibody), micelles, and standard contrast agents by murine macrophages, and sought to determine whether immunomicelles and micelles improve ex vivo imaging of apolipoprotein E knockout (ApoE KO) murine atherosclerosis. Murine RAW 264.7 macrophages were incubated with Gd-DTPA, micelles, and immunomicelles. Cell pellets were prepared and imaged using a 1.5 T MR system with an inversion recovery spin-echo sequence to determine the in vitro T 1 values. Ex vivo analysis of mouse aortas was performed using a 9.4T MR system with a high-spatial-resolution sequence (78 ؋ 39 ؋ 78 m Lesions that result in acute coronary syndromes are typically less than 50% stenosed (1) and are therefore difficult to detect using x-ray coronary angiography. Noninvasive assessment of atherosclerosis by magnetic resonance imaging (MRI) can be used to characterize carotid or aortic plaques (2), but imaging of the coronary arteries is currently limited. The specific targeting of certain plaque components with a paramagnetic contrast agent may therefore improve characterization of atherosclerosis by MRI and perhaps ultimately aid in assessing coronary lesions.In acute coronary syndromes, the lipid core of responsible lesions is rich in macrophage-derived foam cells and other inflammatory cells (3,4). The macrophage scavenger receptor A (MSR-A) is important in the progression of atherosclerosis (5,6) and is expressed at elevated levels in lesions (7). We thus selected the MSR as a target to identify atherosclerotic disease by MRI. In the current study we show that immunomicelles can be produced by linking a monoclonal antibody specific for the murine MSR types I and II (CD204) to gadolinium (Gd)-containing micelles. Our goals were to evaluate the in vitro uptake of immunomicelles, micelles, and standard (Gd-DTPA) MRI contrast agents by murine macrophages, and to determine whether immunomicelles and micelles improve ex vivo imaging of atherosclerotic plaque. MATERIALS AND METHODS Micelle and Immunomicelle FormulationMixed micelles were made from phospholipids (Palmitoyl-oleoyl phosphatidylcholine (POPC), 1,2-Dipalmitoylsn-glycero-3-phosphoethanolamine-N-7-nitro-2-1,3-benzoxadiazol-4-yl (DPPE-NBD), 1,2-Dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-biotinyl (DPPE-Biotin)), a surfactant (Tween 80), and an aliphatic Gd complex (Gd-DOTA-C 16 ) as previously described (8). The POPC and Gd complex were dissolved in a 1:1 chloroform : methanol solution (5 mL). Evaporation under nitrogen flux yielded a thin film that was then rehydrated in hot water (2 mL, 70°C). This solution was sonicated for 15 min at 70 W at a 90% cycle duty while the temperature was kept at 65°C by means of a thermostatic bath. After sonication, Tween 80 was added, followed by another 15 min of sonication. Green fluorescent micelles were ...

The synthesis and photophysical characterisation are reported of a series of cationic, neutral and anionic europium and terbium complexes based on structurally related, nonadentate ligands based on the cyclen macrocycle. Each complex incorporates a tetraazatriphenylene moiety and overall absolute emission quantum yields are in the range 15-40% in aerated aqueous media. Dynamic quenching of the lanthanide excited state occurs with electron-rich donors, e.g. iodide, ascorbate and urate, and a mechanistic interpretation is put forward involving an electron transfer process. The cationic lanthanide complexes are taken up by NlH/3T3 cells and tend to localise inside the cell nucleus.

Intravenously administered MSCs for acute myocardial infarction attenuate the progressive deterioration in LV function and adverse remodeling in mice with large infarcts, and in ischemic cardiomyopathy, they improve LV function, effects apparently modulated in part by systemic anti-inflammatory activities.

The interaction of q = 0 delta- and lambda-Tb and Eu complexes with poly(dAdT), poly(dGdC) and calf-thymus DNA has been examined by absorption, emission and chiroptical spectroscopy and is sensitive to complex helicity, base-pair type and the nature of the lanthanide excited state.