S-EPMC2705289 - Noninvasive in vivo imaging of monocyte trafficking to atherosclerotic lesions. - OmicsDI

Unknown

Dataset Information

Noninvasive in vivo imaging of monocyte trafficking to atherosclerotic lesions.

ABSTRACT: Monocytes play a key role in atherogenesis, but their participation has been discerned largely via ex vivo analyses of atherosclerotic lesions. We sought to establish a noninvasive technique to determine monocyte trafficking to atherosclerotic lesions in live animals.Using a micro-single-photon emission computed tomography small-animal imaging system and a Food and Drug Administration-approved radiotracer ([indium 111] oxyquinoline, (111)In-oxine), we demonstrate here that monocyte recruitment to atherosclerotic lesions can be visualized in a noninvasive, dynamic, and 3-dimensional fashion in live animals. We show in vivo that monocytes are recruited avidly to plaques within days of adoptive transfer. Using micro-single-photon emission computed tomography imaging as a screening tool, we were able to investigate modulatory effects on monocyte recruitment in live animals. We found that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors rapidly and substantially reduce monocyte recruitment to existing atherosclerotic lesions, as imaged here in vivo.This novel approach to track monocytes to atherosclerotic plaques in vivo should have broad applications and create new insights into the pathogenesis of atherosclerosis and other inflammatory diseases.

SUBMITTER: Kircher MF

PROVIDER: S-EPMC2705289 | biostudies-literature | 2008 Jan

REPOSITORIES: biostudies-literature

altmetric image

Publications

Noninvasive in vivo imaging of monocyte trafficking to atherosclerotic lesions.

Kircher Moritz F MF Grimm Jan J Swirski Filip K FK Libby Peter P Gerszten Robert E RE Allport Jennifer R JR Weissleder Ralph R

Circulation 20080102 3

<h4>Background</h4>Monocytes play a key role in atherogenesis, but their participation has been discerned largely via ex vivo analyses of atherosclerotic lesions. We sought to establish a noninvasive technique to determine monocyte trafficking to atherosclerotic lesions in live animals.<h4>Methods and results</h4>Using a micro-single-photon emission computed tomography small-animal imaging system and a Food and Drug Administration-approved radiotracer ([indium 111] oxyquinoline, (111)In-oxine), ...[more]

Similar Datasets

Project description:This study sought to evaluate the in vivo magnetic resonance imaging (MRI) efficacy of manganese [Mn(II)] molecular imaging probes targeted to oxidation-specific epitopes (OSE).OSE are critical in the initiation, progression, and destabilization of atherosclerotic plaques. Gadolinium [Gd(III)]-based MRI agents can be associated with systemic toxicity. Mn is an endogenous, biocompatible, paramagnetic metal ion that has poor MR efficacy when chelated, but strong efficacy when released within cells.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-T) evaluated in apolipoprotein-deficient (apoE(-/-)) and low-density lipoprotein receptor negative (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.In vitro studies demonstrated that targeted Mn micelles accumulate in macrophages when pre-exposed to MDA-LDL with ?10× increase in longitudinal relativity. Following intravenous injection, strong MR signal enhancement was observed 48 to 72 h after administration of targeted Mn micelles, with colocalization 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.This study demonstrates that biocompatible multimodal Mn-based molecular imaging probes detect OSE within atherosclerotic plaques and may facilitate clinical translation of noninvasive imaging of human atherosclerosis.

Project description:The leading causes of morbidity and mortality globally are cardiovascular diseases, and nanomedicine can provide many improvements including disease-specific targeting, early detection, and local delivery of diagnostic agents. To this end, we designed fibrin-binding, peptide amphiphile micelles (PAMs), achieved by incorporating the targeting peptide cysteine-arginine-glutamic acid-lysine-alanine (CREKA), with two types of amphiphilic molecules containing the gadoliniuim (Gd) chelator diethylenetriaminepentaacetic acid (DTPA), DTPA-bis(stearylamide)(Gd), and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(poly(ethylene glycol) (PEG))-2000]-DTPA(Gd) (DSPE-PEG2000-DTPA(Gd)). The material characteristics of the resulting nanoparticle diagnostic probes, clot-binding properties in vitro, and contrast enhancement and safety for dual, optical imaging-magnetic resonance imaging (MRI) were evaluated in the atherosclerotic mouse model. Transmission electron micrographs showed a homogenous population of spherical micelles for formulations containing DSPE-PEG2000-DTPA(Gd), whereas both spherical and cylindrical micelles were formed upon mixing DTPA-BSA(Gd) and CREKA amphiphiles. Clot-binding assays confirmed DSPE-PEG2000-DTPA(Gd)-based CREKA micelles targeted clots over 8-fold higher than nontargeting (NT) counterpart micelles, whereas no difference was found between CREKA and NT, DTPA-BSA(Gd) micelles. However, in vivo MRI and optical imaging studies of the aortas and hearts showed fibrin specificity was conferred by the peptide ligand without much difference between the nanoparticle formulations or shapes. Biodistribution studies confirmed that all micelles were cleared through both the reticuloendothelial system and renal clearance, and histology showed no signs of necrosis. In summary, these studies demonstrate the successful synthesis, and the molecular imaging capabilities of two types of CREKA-Gd PAMs for atherosclerosis. Moreover, we demonstrate the differences in micelle formulations and shapes and their outcomes in vitro versus in vivo for site-specific, diagnostic strategies, and provide the groundwork for the detection of thrombosis via contrast-enhancing agents and concurrent therapeutic delivery for theranostic applications.

Project description:RATIONALE: A noninvasive tool allowing the detection of vulnerable atherosclerotic plaques is highly needed. By combining nanomolar affinities and fast blood clearance, nanobodies represent potential radiotracers for cardiovascular molecular imaging. Vascular cell adhesion molecule-1 (VCAM1) constitutes a relevant target for molecular imaging of atherosclerotic lesions. OBJECTIVE: We aimed to generate, radiolabel, and evaluate anti-VCAM1 nanobodies for noninvasive detection of atherosclerotic lesions. METHODS AND RESULTS: Ten anti-VCAM1 nanobodies were generated, radiolabeled with technetium-99m, and screened in vitro on mouse and human recombinant VCAM1 proteins and endothelial cells and in vivo in apolipoprotein E-deficient (ApoE(-/-)) mice. A nontargeting control nanobody was used in all experiments to demonstrate specificity. All nanobodies displayed nanomolar affinities for murine VCAM1. Flow cytometry analyses using human human umbilical vein endothelial cells indicated murine and human VCAM1 cross-reactivity for 6 of 10 nanobodies. The lead compound cAbVCAM1-5 was cross-reactive for human VCAM1 and exhibited high lesion-to-control (4.95±0.85), lesion-to-heart (8.30±1.11), and lesion-to-blood ratios (4.32±0.48) (P<0.05 versus control C57Bl/6J mice). Aortic arch atherosclerotic lesions of ApoE(-/-) mice were successfully identified by single-photon emission computed tomography imaging. (99m)Tc-cAbVCAM1-5 binding specificity was demonstrated by in vivo competition experiments. Autoradiography and immunohistochemistry further confirmed cAbVCAM1-5 uptake in VCAM1-positive lesions. CONCLUSIONS: The (99m)Tc-labeled, anti-VCAM1 nanobody cAbVCAM1-5 allowed noninvasive detection of VCAM1 expression and displayed mouse and human cross-reactivity. Therefore, this study demonstrates the potential of nanobodies as a new class of radiotracers for cardiovascular applications. The nanobody technology might evolve into an important research tool for targeted imaging of atherosclerotic lesions and has the potential for fast clinical translation.