Scavenger Receptor-AI–Targeted Iron Oxide Nanoparticles for In Vivo MRI Detection of Atherosclerotic Lesions

Translational Molecular Imaging Tool of Vulnerable Carotid Plaque: Evaluate Effects of Statin Therapy on Plaque Inflammation and American Heart Association-Defined Risk Levels in Cuff-Implanted Apolipoprotein E-Deficient Mice

Identification of high-risk carotid plaques in asymptomatic patients remains a challenging but crucial step in stroke prevention. The challenge is to accurately monitor the development of high-risk carotid plaques and promptly identify patients, who are unresponsive to best medical therapy, and hence targeted for carotid surgical interventions to prevent stroke. Inflammation is a key operator in destabilisation of plaques prior to clinical sequelae. Currently, there is a lack of imaging tool in routine clinical practice, which allows assessment of inflammatory activity within the atherosclerotic plaque. Herein, we have used a periarterial cuff to generate a progressive carotid atherosclerosis model in apolipoprotein E-deficient mice. This model produced clinically relevant plaques with different levels of risk, fulfilling American Heart Association (AHA) classification, at specific timepoints and locations, along the same carotid artery. Exploiting this platform, we have developed smart molecular magnetic resonance imaging (MRI) probes consisting of dual-targeted microparticles of iron oxide (DT-MPIO) against VCAM-1 and P-selectin, to evaluate the anti-inflammatory effect of statin therapy on progressive carotid atherosclerosis. We demonstrated that in vivo DT-MPIO-enhanced MRI can (i) quantitatively track plaque inflammation from early to advanced stage; (ii) identify and characterise high-risk inflamed, vulnerable plaques; and (iii) monitor the response to statin therapy longitudinally. Moreover, this molecular imaging-defined therapeutic response was validated using AHA classification of human plaques, a clinically relevant parameter, approximating the clinical translation of this tool. Further development and translation of this molecular imaging tool into the clinical arena may potentially facilitate more accurate risk stratification, permitting timely identification of the high-risk patients for prophylactic carotid intervention, affording early opportunities for stroke prevention in the future.

Nanotechnology in coronary heart disease

Coronary heart disease (CHD) is one of the major causes of death and disability worldwide, especially in low- and middle-income countries and among older populations. Conventional diagnostic and therapeutic approaches have limitations such as low sensitivity, high cost and side effects. Nanotechnology offers promising alternative strategies for the diagnosis and treatment of CHD by exploiting the unique properties of nanomaterials. In this review, we use bibliometric analysis to identify research hotspots in the application of nanotechnology in CHD and provide a comprehensive overview of the current state of the art. Nanomaterials with enhanced imaging and biosensing capabilities can improve the early detection of CHD through advanced contrast agents and high-resolution imaging techniques. Moreover, nanomaterials can facilitate targeted drug delivery, tissue engineering and modulation of inflammation and oxidative stress, thus addressing multiple aspects of CHD pathophysiology. We discuss the application of nanotechnology in CHD diagnosis (imaging and sensors) and treatment (regulation of macrophages, cardiac repair, anti-oxidative stress), and provide insights into future research directions and clinical translation. This review serves as a valuable resource for researchers and clinicians seeking to harness the potential of nanotechnology in the management of CHD. STATEMENT OF SIGNIFICANCE: Coronary heart disease (CHD) is the one of leading cause of death and disability worldwide. Nanotechnology offers new strategies for diagnosing and treating CHD by exploiting the unique properties of nanomaterials. This review uses bibliometric analysis to uncover research trends in the use of nanotechnology for CHD. We discuss the potential of nanomaterials for early CHD detection through advanced imaging and biosensing, targeted drug delivery, tissue engineering, and modulation of inflammation and oxidative stress. We also offer insights into future research directions and potential clinical applications. This work aims to guide researchers and clinicians in leveraging nanotechnology to improve CHD patient outcomes and quality of life.

Atherosclerosis treatment with nanoagent: potential targets, stimulus signals and drug delivery mechanisms

Cardiovascular disease (CVDs) is the first killer of human health, and it caused up at least 31% of global deaths. Atherosclerosis is one of the main reasons caused CVDs. Oral drug therapy with statins and other lipid-regulating drugs is the conventional treatment strategies for atherosclerosis. However, conventional therapeutic strategies are constrained by low drug utilization and non-target organ injury problems. Micro-nano materials, including particles, liposomes, micelles and bubbles, have been developed as the revolutionized tools for CVDs detection and drug delivery, specifically atherosclerotic targeting treatment. Furthermore, the micro-nano materials also could be designed to intelligently and responsive targeting drug delivering, and then become a promising tool to achieve atherosclerosis precision treatment. This work reviewed the advances in atherosclerosis nanotherapy, including the materials carriers, target sites, responsive model and treatment results. These nanoagents precisely delivery the therapeutic agents to the target atherosclerosis sites, and intelligent and precise release of drugs, which could minimize the potential adverse effects and be more effective in atherosclerosis lesion.

Scavenger receptor-AI targeted theranostic nanoparticles for regression of atherosclerotic plaques via ABCA1 modulation

ATP-binding cassette transporter A1 (ABCA1) plays a crucial role in atherosclerotic formation through mediated cholesterol efflux in macrophage-derived foam cells. In this study, a scavenger receptors AI (SR-AI) targeted theranostic nanoparticles was constructed for atherosclerosis regression via ABCA1 activation in foam cells. ABCA1-upregulator 5242331 and IR780 were encapsulated in PLGA-PEG micelles which were conjugated with SR-AI targeting peptide (PP1) to formulate the nanoparticles (SAU-NPs). Immunostaining revealed that SR-AI was highly expressed both in macrophage foam cells and in atherosclerotic plaque of ApoE^-/- mice. The SAU-NPs have shown more active targeting to plaque lesion with higher stability compared with non-SR-AI targeted nanoparticles. The transformation from macrophage to foam cells was inhibited by SAU-NPs carried 5242331. Cholesterol deposition was effectively reduced in foam cells by SAU-NPs through activating the LXRα-ABCA1/ABCG1/SR-BI pathway. In conclusion, theranostic SAU-NPs which carried ABCA1-upregulator 5242331 exert beneficial effects on atherosclerosis regression via LXRα activation.

Nanoparticles in the diagnosis and treatment of vascular aging and related diseases

Aging-induced alternations of vasculature structures, phenotypes, and functions are key in the occurrence and development of vascular aging-related diseases. Multiple molecular and cellular events, such as oxidative stress, mitochondrial dysfunction, vascular inflammation, cellular senescence, and epigenetic alterations are highly associated with vascular aging physiopathology. Advances in nanoparticles and nanotechnology, which can realize sensitive diagnostic modalities, efficient medical treatment, and better prognosis as well as less adverse effects on non-target tissues, provide an amazing window in the field of vascular aging and related diseases. Throughout this review, we presented current knowledge on classification of nanoparticles and the relationship between vascular aging and related diseases. Importantly, we comprehensively summarized the potential of nanoparticles-based diagnostic and therapeutic techniques in vascular aging and related diseases, including cardiovascular diseases, cerebrovascular diseases, as well as chronic kidney diseases, and discussed the advantages and limitations of their clinical applications.

N-Acetyl Galactosamine Targeting: Paving the Way for Clinical Application of Nucleotide Medicines in Cardiovascular Diseases

While the promise of oligonucleotide therapeutics, such as (chemically modified) ASO (antisense oligonucleotides) and short interfering RNAs, is undisputed from their introduction onwards, their unfavorable pharmacokinetics and intrinsic capacity to mobilize innate immune responses, were limiting widespread clinical use. However, these major setbacks have been tackled by breakthroughs in chemistry, stability and delivery. When aiming an intervention hepatic targets, such as lipid and sugar metabolism, coagulation, not to mention cancer and virus infection, introduction of N-acetylgalactosamine aided targeting technology has advanced the field profoundly and by now a dozen of N-acetylgalactosamine therapeutics for these indications have been approved for clinical use or have progressed to clinical trial stage 2 to 3 testing. This technology, in combination with major advances in oligonucleotide stability allows safe and durable intervention in targets that were previously deemed undruggable, such as Lp(a) and PCSK9 (proprotein convertase subtilisin/kexin type 9), at high efficacy and specificity, often with as little as 2 doses per year. Their successful use even the most visionary would not have predicted 2 decades ago. Here, we will review the evolution of N-acetylgalactosamine technology. We shall outline their fundamental design principles and merits, and their application for the delivery of oligonucleotide therapeutics to the liver. Finally, we will discuss the perspectives of N-acetylgalactosamine technology and propose directions for future research in receptor targeted delivery of these gene medicines.

Iron Oxide Nanoparticles in Regenerative Medicine and Tissue Engineering

In recent years, many promising nanotechnological approaches to biomedical research have been developed in order to increase implementation of regenerative medicine and tissue engineering in clinical practice. In the meantime, the use of nanomaterials for the regeneration of diseased or injured tissues is considered advantageous in most areas of medicine. In particular, for the treatment of cardiovascular, osteochondral and neurological defects, but also for the recovery of functions of other organs such as kidney, liver, pancreas, bladder, urethra and for wound healing, nanomaterials are increasingly being developed that serve as scaffolds, mimic the extracellular matrix and promote adhesion or differentiation of cells. This review focuses on the latest developments in regenerative medicine, in which iron oxide nanoparticles (IONPs) play a crucial role for tissue engineering and cell therapy. IONPs are not only enabling the use of non-invasive observation methods to monitor the therapy, but can also accelerate and enhance regeneration, either thanks to their inherent magnetic properties or by functionalization with bioactive or therapeutic compounds, such as drugs, enzymes and growth factors. In addition, the presence of magnetic fields can direct IONP-labeled cells specifically to the site of action or induce cell differentiation into a specific cell type through mechanotransduction.

Development of Molecular Magnetic Resonance Imaging Tools for Risk Stratification of Carotid Atherosclerotic Disease Using Dual-Targeted Microparticles of Iron Oxide

Identification of patients with high-risk asymptomatic carotid plaques remains a challenging but crucial step in stroke prevention. Inflammation is the key factor that drives plaque instability. Currently, there is no imaging tool in routine clinical practice to assess the inflammatory status within atherosclerotic plaques. We have developed a molecular magnetic resonance imaging (MRI) tool to quantitatively report the inflammatory activity in atherosclerosis using dual-targeted microparticles of iron oxide (DT-MPIO) against P-selectin and VCAM-1 as a smart MRI probe. A periarterial cuff was used to generate plaques with varying degree of phenotypes, inflammation and risk levels at specific locations along the same single carotid artery in an Apolipoprotein-E-deficient mouse model. Using this platform, we demonstrated that in vivo DT-MPIO-enhanced MRI can (i) target high-risk vulnerable plaques, (ii) differentiate the heterogeneity (i.e. high vs intermediate vs low-risk plaques) within the asymptomatic plaque population and (iii) quantitatively report the inflammatory activity of local plaques in carotid artery. This novel molecular MRI tool may allow characterisation of plaque vulnerability and quantitative reporting of inflammatory status in atherosclerosis. This would permit accurate risk stratification by identifying high-risk asymptomatic individual patients for prophylactic carotid intervention, expediting early stroke prevention and paving the way for personalised management of carotid atherosclerotic disease.

In vivostudy of iron oxide-calcium phosphate composite nanoparticles for delivery to atherosclerosis

Atherosclerosis is a macrophage-related inflammatory disease that remains a leading cause of death worldwide. Magnetic iron oxide (IO) nanocrystals are clinically used as magnetic resonance imaging contrast agents and their application as a detection agent for macrophages in arterial lesions has been studied extensively. We recently fabricated heparin-modified calcium phosphate (CaP) nanoparticles loaded with a large number of IO nanocrystals via coprecipitation from a supersaturated CaP solution supplemented with heparin and ferucarbotran (IO nanocrystals coated with carboxydextran). In this study, we further increased the content of IO nanocrystals in the heparin-modified IO-CaP composite nanoparticles by increasing the ferucarbotran concentration in the supersaturated CaP solution. The increase in nanoparticle IO content caused a decrease in particle diameter without impairing its dispersibility; the nanoparticles remained dispersed in water for up to 2 h due to electrostatic repulsion between particles due to the surface modification with heparin. The nanoparticles were more effectively taken up by murine RAW264.7 macrophages compared to free ferucarbotran without showing significant cytotoxicity. A preliminaryin vivostudy showed that the nanoparticles injected intravenously into mice delivered more IO nanocrystals to macrophage-rich carotid arterial lesions than free ferucarbotran. Our nanoparticles have potential as a delivery agent of IO nanocrystals to macrophages in arterial lesions.

Multifunctional pathology-mapping theranostic nanoplatforms for US/MR imaging and ultrasound therapy of atherosclerosis

Atherosclerotic thrombosis is the leading cause of most life-threatening cardiovascular diseases (CVDs), particularly as a result of rupture or erosion of vulnerable plaques. Rupture or erosion-prone plaques are quite different in cellular composition and immunopathology, requiring different treatment strategies. The current imaging technology cannot distinguish the types of vulnerable plaques, and thus empirical treatment is still applied to all without a tailored and precise treatment. Herein, we propose a novel strategy called "Multifunctional Pathology-mapping Theranostic Nanoplatform (MPmTN)" for the tailored treatment of plaques based on the pathological classification. MPmTNs are made up of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs), containing contrast imaging materials Fe₃O₄ and perfluoropentane (PFP), and coated with specific plaque-targeted peptides PP1 and cyclic RGD. The PFP encapsulated inside the MPmTN can undergo a phase change from nanodroplets to gas microbubbles under therapeutic ultrasound (TUS) exposure. The acoustic and biological effects induced by TUS and disruption of microbubbles may further promote therapeutic effects. Hypothetically, MPmTN NPs can target the rupture-prone plaque via the binding of PP1 to class A scavenger receptors (SR-A) on macrophages, induce the apoptosis due to TUS exposure and thus reduce the chronic soakage of inflammatory cells. The MPmTN NPs can also target the erosion-prone plaque through the binding of cRGD to glycoprotein (GP) IIb/IIIa on activated platelets and promote platelet disaggregation under TUS exposure. Therefore, MPmTNs may work as a multifunctional pathology-mapping therapeutic agent. Our in vitro results show that the MPmTN with PP1 and cRGD peptides had a high binding affinity both for activated macrophages and blood clots. Under TUS exposure, the MPmTN could effectively induce macrophage apoptosis, destroy thrombus and exhibit good imaging properties for ultrasound (US) and MRI. In apoE^-/- mice, MPmTNs can selectively accumulate at the plaque site and reduce the T₂-weighted signal. The apoptosis of macrophages and disaggregation of activated platelets on the plaques were also confirmed in vivo. In summary, this study provides a potential strategy for a tailored treatment of vulnerable plaques based on their pathological nature and a multimodal imaging tool for the risk stratification and assessment of therapeutic efficacy.

Evaluation of Plaque Characteristics and Inflammation Using Magnetic Resonance Imaging

Atherosclerosis is an inflammatory disease of large and medium-sized arteries, characterized by the growth of atherosclerotic lesions (plaques). These plaques often develop at inner curvatures of arteries, branchpoints, and bifurcations, where the endothelial wall shear stress is low and oscillatory. In conjunction with other processes such as lipid deposition, biomechanical factors lead to local vascular inflammation and plaque growth. There is also evidence that low and oscillatory shear stress contribute to arterial remodeling, entailing a loss in arterial elasticity and, therefore, an increased pulse-wave velocity. Although altered shear stress profiles, elasticity and inflammation are closely intertwined and critical for plaque growth, preclinical and clinical investigations for atherosclerosis mostly focus on the investigation of one of these parameters only due to the experimental limitations. However, cardiovascular magnetic resonance imaging (MRI) has been demonstrated to be a potent tool which can be used to provide insights into a large range of biological parameters in one experimental session. It enables the evaluation of the dynamic process of atherosclerotic lesion formation without the need for harmful radiation. Flow-sensitive MRI provides the assessment of hemodynamic parameters such as wall shear stress and pulse wave velocity which may replace invasive and radiation-based techniques for imaging of the vascular function and the characterization of early plaque development. In combination with inflammation imaging, the analyses and correlations of these parameters could not only significantly advance basic preclinical investigations of atherosclerotic lesion formation and progression, but also the diagnostic clinical evaluation for early identification of high-risk plaques, which are prone to rupture. In this review, we summarize the key applications of magnetic resonance imaging for the evaluation of plaque characteristics through flow sensitive and morphological measurements. The simultaneous measurements of functional and structural parameters will further preclinical research on atherosclerosis and has the potential to fundamentally improve the detection of inflammation and vulnerable plaques in patients.

USPIOs as targeted contrast agents in cardiovascular magnetic resonance imaging

PURPOSE OF REVIEW

We aim to discuss the diagnostic use of ultra-small superparamagnetic iron oxide (USPIOs) including ferumoxytol in targeted cardiovascular magnetic resonance imaging (MRI).

RECENT FINDINGS

Ferumoxytol is the only USPIO clinically available in the U.S. and is a negatively charged USPIO that has potential use for tracking and characterization of macrophage-infiltrated cardiovascular structures. As an iron supplement that is approved for treatment of iron deficiency anemia, the iron core of ferumoxytol is incorporated into the body once it is phagocytosed by macrophages. In organs or tissues with high inflammatory cellular infiltration, such as atherosclerotic plaques and myocardial infarction, localization of iron-laden macrophages can be visualized on delayed MRI. The iron core of ferumoxytol alters the magnetic susceptibility and results in shortening of T2* and T2 relaxation rates. Areas with high concentration appear hypointense (negative contrast) on T2 and T2* MRI. Recently, in vitro findings support the potential specificity of ferumoxytol interactions with macrophage subtypes, which has implications for therapeutic interventions. With increasing concerns about gadolinium retention in the brain and other tissues, the value of ferumoxytol-enhanced MR for targeted clinical imaging is aided by its positive safety profile in patients with impaired renal function.

SUMMARY

This paper discusses pharmacokinetic properties of USPIOs with a focus on ferumoxytol, and summarizes relevant in vitro, animal, and human studies investigating the diagnostic use of USPIOs in targeted contrast-enhanced imaging. We also discuss future directions for USPIOs as targeted imaging agents and associated challenges.

Nanomaterial-Mediated Theranostics for Vascular Diseases

Nanotechnology could offer a new complementary strategy for the treatment of vascular diseases including coronary, carotid, or peripheral arterial disease due to narrowing or blockage of the artery caused by atherosclerosis. These arterial diseases manifest correspondingly as angina and myocardial infarction, stroke, and intermittent claudication of leg muscles during exercise. The pathogenesis of atherosclerosis involves biological events at the cellular and molecular level, thus targeting these using nanomaterials precisely and effectively could result in a better outcome. Nanotechnology can mitigate the pathological events by enhancing the therapeutic efficacy of the therapeutic agent by delivering it at the point of a lesion in a controlled and efficacious manner. Further, combining therapeutics with imaging will enhance the theranostic ability in atherosclerosis. Additionally, nanoparticles can provide a range of delivery systems for genes, proteins, cells, and drugs, which individually or in combination can address various problems within the arteries. Imaging studies combined with nanoparticles helps in evaluating the disease progression as well as the response to the treatment because imaging and diagnostic agents can be delivered precisely to the targeted destinations via nanocarriers. This review focuses on the use of nanotechnology in theranostics of coronary artery and peripheral arterial disease.

Magnetic mesoporous silica nanoparticles-aided dual MR/NIRF imaging to identify macrophage enrichment in atherosclerotic plaques

Active foamy macrophage enrichment drives atherosclerotic plaque initiation and evolution, and is the prominent target for precisely identifying vulnerable plaque. Precise imaging of high-risk plaque allows promotion of treatment and prevention of vascular pathema. However, current iron oxide (IO) nanoparticles-based magnetic resonance (MR) imaging of plaque is often limited by insufficient perfusion and nonspecific accumulation of peri-aortic lymph nodes. Besides that, intrinsic defects of MR also impede its use for accurately identifying plaque details. Herein, by conjugating with PP1 peptide, a novel magnetic mesoporous silica nanoparticle (PIMI) loaded with near-infrared fluorescence (NIRF) dye (IR820) was fabricated to specifically target and quantify macrophage enrichment of atherosclerotic plaque in ApoE^-/- mice using dual MR/NIRF imaging. Biocompatibility experiments ulteriorly confirmed the high safety of PIMI nanoparticles in vivo, which lays the foundation of next-generation contrast agent for recognizing macrophage-rich plaque in the near future.

Application of a Scavenger Receptor A1-Targeted Polymeric Prodrug Platform for Lymphatic Drug Delivery in HIV

We have developed a macromolecular prodrug platform based on poly(l-lysine succinylated) (PLS) that targets scavenger receptor A1 (SR-A1), a receptor expressed by myeloid and endothelial cells. We demonstrate the selective uptake of PLS by murine macrophage, RAW 264.7 cells, which was eliminated upon cotreatment with the SR-A inhibitor polyinosinic acid (poly I). Further, we observed no uptake of PLS in an SR-A1-deficient RAW 264.7 cell line, even after 24 h incubation. In mice, PLS distributed to lymphatic organs following i.v. injection, as observed by ex vivo fluorescent imaging, and accumulated in lymph nodes following both i.v. and i.d. administrations, based on immunohistochemical analysis with high-resolution microscopy. As a proof-of-concept, the HIV antiviral emtricitabine (FTC) was conjugated to the polymer's succinyl groups via ester bonds, with a drug loading of 14.2% (wt/wt). The prodrug (PLS-FTC) demonstrated controlled release properties in vitro with a release half-life of 15 h in human plasma and 29 h in esterase-inhibited plasma, indicating that drug release occurs through both enzymatic and nonenzymatic mechanisms. Upon incubation of PLS-FTC with human peripheral blood mononuclear cells (PBMCs), the released drug was converted to the active metabolite FTC triphosphate. In a pharmacokinetic study in rats, the prodrug achieved ∼7-19-fold higher concentrations in lymphatic tissues compared to those in FTC control, supporting lymphatic-targeted drug delivery. We believe that the SR-A1-targeted macromolecular PLS prodrug platform has extraordinary potential for the treatment of infectious diseases.

Construction of dual nanomedicines for the imaging and alleviation of atherosclerosis

Magnetic resonance imaging (MRI) is an essential tool for the diagnosis of atherosclerosis, a chronic cardiovascular disease. MRI primarily uses superparamagnetic iron oxide (SPIO) as a contrast agent. However, SPIO integrated with therapeutic drugs has rarely been studied. In this study, we explored biocompatible paramagnetic iron-oxide nanoparticles (NPs) in a complex with low pH-sensitive cyclodextrin for the diagnostic imaging and treatment of atherosclerosis. The NPs were conjugated with profilin-1 antibody (PFN1) to specifically target vascular smooth muscle cells (VSMCs) in the atherosclerotic plaque and integrated with the anti-inflammatory drug, rapamycin. The PFN1-CD-MNPs were easily binded to the VSMCs, indicating their good biocompatibility and low renal toxicity over the long term. Ex vivo near-infrared fluorescence (NIRF) imaging and in vivo MRI indicated the accumulation of PFN1-CD-MNPs in the atherosclerotic plaque. The RAP@PFN1-CD-MNPs alleviated the progression of arteriosclerosis. Thus, PFN1-CD-MNPs served not only as multifunctional imaging probes but also as nanovehicles for the treatment of atherosclerosis.

Anti-atherogenic effects of CD36-targeted epigallocatechin gallate-loaded nanoparticles

Intimal macrophages play a critical role in atherosclerotic lesion initiation and progression by taking up oxidized low-density lipoprotein (oxLDL) and promoting inflammatory process. 1-(Palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine (KOdiA-PC), a major type of oxidized phosphatidylcholines (PC) found on oxLDL, has a high binding affinity to the macrophage scavenger receptor CD36 and participates in CD36-mediated recognition and uptake of oxLDL by intimal macrophages. We successfully synthesized epigallocatechin gallate (EGCG)-loaded nanoparticles (Enano), which were composed of EGCG, PC, (+) alpha-tocopherol acetate, and surfactant. We also incorporated KOdiA-PC on the surface of Enano to make ligand-coated Enano (L-Enano) to target intimal macrophages. The objectives of this study were to determine the anti-atherogenic effects of Enano and L-Enano in LDL receptor null (LDLr-/-) mice. Our in vitro data demonstrated that L-Enano had a higher binding affinity to mouse peritoneal macrophages than Enano. This high binding affinity was diminished by CD36 antibodies or knockdown of the CD36 receptor in mouse peritoneal macrophages, confirming the specific binding of L-Enano to the macrophage CD36 receptor. LDLr-/- mice were randomly divided to six groups and received weekly tail vein injection with PBS, EGCG, void nanoparticles (Vnano), Enano, ligand-coated Vnano (L-Vnano), or L-Enano once per week for 22 weeks. The dose of EGCG was 25 mg per kg body weight. L-Enano at 20 μg/mL significantly decreased production of monocyte chemoattractant protein-1, tumor necrosis factor alpha, and interleukin-6 from mouse macrophages, while having no effect on their plasma levels compared to the PBS control. There were no significant differences in blood lipid profiles among six treatment groups. Mice treated with L-Enano also had significantly smaller lesion surface areas on aortic arches compared to the PBS control. Liver EGCG content was decreased by treatments in the order of EGCG>Enano>L-Enano. Native EGCG had inhibitory effects on liver and body fat accumulation. This molecular target approach signals an important step towards inhibiting atherosclerosis development via targeted delivery of bioactive compounds to intimal macrophages.

Human macrophage responses to metal-oxide nanoparticles: a review

Nanomaterials have been widely used in our daily lives in medicine, cosmetics, paints, textiles and food products. Many studies aim to determine their biological effects in different types of cells. The interaction of these materials with the immune system leads to reactions by modifying the susceptibility or resistance of the host body which could induce adverse health effects. Macrophages, as specific cells of the innate immune response, play a crucial role in the human defence system to foreign agents. They can be used as a reliable test object for the investigation of immune responses under nanomaterials exposure displayed by expression of a variety of receptors and active secretion of key signalling substances for these processes. This report covers studies of human macrophage behaviours upon exposure of nanomaterials. We focused on their interaction with metal-oxide nanoparticles as these are largely used in medical and cosmetics applications. The discussion and summary of these studies can guide the development of new nanomaterials, which are, at the same time, safe and useful for new purposes, especially for health applications.

Imaging vulnerable plaques by targeting inflammation in atherosclerosis using fluorescent-labeled dual-ligand microparticles of iron oxide and magnetic resonance imaging

OBJECTIVE

Identification of patients with high-risk asymptomatic carotid plaques remains an elusive but essential step in stroke prevention. Inflammation is a key process in plaque destabilization and a prelude to clinical sequelae. There are currently no clinical imaging tools to assess the inflammatory activity within plaques. This study characterized inflammation in atherosclerosis using dual-targeted microparticles of iron oxide (DT-MPIO) as a magnetic resonance imaging (MRI) probe.

METHODS

DT-MPIO were used to detect and characterize inflammatory markers, vascular cell adhesion molecule 1 (VCAM-1). and P-selectin on (1) tumor necrosis factor-α-treated cells by immunocytochemistry and (2) aortic root plaques of apolipoprotein-E deficient mice by in vivo MRI. Furthermore, apolipoprotein E-deficient mice with focal carotid plaques of different phenotypes were developed by means of periarterial cuff placement to allow in vivo molecular MRI using these probes. The association between biomarkers and the magnetic resonance signal in different contrast groups was assessed longitudinally in these models.

RESULTS

Immunocytochemistry confirmed specificity and efficacy of DT-MPIO to VCAM-1 and P-selectin. Using this in vivo molecular MRI strategy, we demonstrated (1) the DT-MPIO-induced magnetic resonance signal tracked with VCAM-1 (r = 0.69; P = .014), P-selectin (r = 0.65; P = .022), and macrophage content (r = 0.59; P = .045) within aortic root plaques and (2) high-risk inflamed plaques were distinguished from noninflamed plaques in the murine carotid artery within a practical clinical imaging time frame.

CONCLUSIONS

These molecular MRI probes constitute a novel imaging tool for in vivo characterization of plaque vulnerability and inflammatory activity in atherosclerosis. Further development and translation into the clinical arena will facilitate more accurate risk stratification in carotid atherosclerotic disease in the future.

Fucoidan Prolongs the Circulation Time of Dextran-Coated Iron Oxide Nanoparticles

The magnetic properties and safety of dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs) have facilitated their clinical use as MRI contrast agents and stimulated research on applications for SPIONs in particle imaging and magnetic hyperthermia. The wider clinical potential of SPIONs, however, has been limited by their rapid removal from circulation via the reticuloendothelial system (RES). We explored the possibility of extending SPION circulatory time using fucoidan, a seaweed-derived food supplement, to inhibit RES uptake. The effects of fucoidan on SPION biodistribution were evaluated using ferucarbotran, which in its pharmaceutical formulation (Resovist) targets the RES. Ferucarbotran was radiolabeled at the iron oxide core with technetium-99m (99mTc; t1/2 = 6 h) or zirconium-89 (89Zr; t1/2 = 3.3 days). Results obtained with 99mTc-ferucarbotran demonstrated that administration of fucoidan led to a 4-fold increase in the circulatory half-life (t1/2 slow) from 37.4 to 150 min (n = 4; P < 0.0001). To investigate whether a longer circulatory half-life could lead to concomitant increased tumor uptake, the effects of fucoidan were tested with 89Zr-ferucarbotran in mice bearing syngeneic subcutaneous (GL261) tumors. In this model, the longer circulatory half-life achieved with fucoidan was associated with a doubling in tumor SPION uptake (n = 5; P < 0.001). Fucoidan was also effective in significantly increasing the circulatory half-life of perimag-COOH, a commercially available SPION with a larger hydrodynamic size (130 nm) than ferucarbotran (65 nm). These findings indicate successful diversion of SPIONs away from the hepatic RES and show realistic potential for future clinical applications.

Pathophysiological relevance of macrophage subsets in atherogenesis

Macrophages are highly heterogeneous and plastic cells. They were shown to play a critical role in all stages of atherogenesis, from the initiation to the necrotic core formation and plaque rupture. Lesional macrophages primarily derive from blood monocyte, but local macrophage proliferation as well as differentiation from smooth muscle cells have also been described. Within atherosclerotic plaques, macrophages rapidly respond to changes in the microenvironment, shifting between pro- (M1) or anti-inflammatory (M2) functional phenotypes. Furthermore, different stimuli have been associated with differentiation of newly discovered M2 subtypes: IL-4/IL-13 (M2a), immunecomplex (M2b), IL-10/glucocorticoids (M2c), and adenosine receptor agonist (M2d). More recently, additional intraplaque macrophage phenotypes were also recognized in response to CXCL4 (M4), oxidized phospholipids (Mox), haemoglobin/haptoglobin complexes (HAmac/M(Hb)), and heme (Mhem). Such macrophage polarization was described as a progression among multiple phenotypes, which reflect the activity of different transcriptional factors and the cross-talk between intracellular signalling. Finally, the distribution of macrophage subsets within different plaque areas was markedly associated with cardiovascular (CV) vulnerability. The aim of this review is to update the current knowledge on the role of macrophage subsets in atherogenesis. In addition, the molecular mechanisms underlying macrophage phenotypic shift will be summarised and discussed. Finally, the role of intraplaque macrophages as predictors of CV events and the therapeutic potential of these cells will be discussed.

Recommendation on Design, Execution, and Reporting of Animal Atherosclerosis Studies: A Scientific Statement From the American Heart Association

Animal studies are a foundation for defining mechanisms of atherosclerosis and potential targets of drugs to prevent lesion development or reverse the disease. In the current literature, it is common to see contradictions of outcomes in animal studies from different research groups, leading to the paucity of extrapolations of experimental findings into understanding the human disease. The purpose of this statement is to provide guidelines for development and execution of experimental design and interpretation in animal studies. Recommendations include the following: (1) animal model selection, with commentary on the fidelity of mimicking facets of the human disease; (2) experimental design and its impact on the interpretation of data; and (3) standard methods to enhance accuracy of measurements and characterization of atherosclerotic lesions.

Recommendation on Design, Execution, and Reporting of Animal Atherosclerosis Studies: A Scientific Statement From the American Heart Association

Animal studies are a foundation for defining mechanisms of atherosclerosis and potential targets of drugs to prevent lesion development or reverse the disease. In the current literature, it is common to see contradictions of outcomes in animal studies from different research groups, leading to the paucity of extrapolations of experimental findings into understanding the human disease. The purpose of this statement is to provide guidelines for development and execution of experimental design and interpretation in animal studies. Recommendations include the following: (1) animal model selection, with commentary on the fidelity of mimicking facets of the human disease; (2) experimental design and its impact on the interpretation of data; and (3) standard methods to enhance accuracy of measurements and characterization of atherosclerotic lesions.

Nanomedicines for dysfunctional macrophage-associated diseases

Macrophages play vital functions in host inflammatory reaction, tissue repair, homeostasis and immunity. Dysfunctional macrophages have significant pathophysiological impacts on diseases such as cancer, inflammatory diseases (rheumatoid arthritis and inflammatory bowel disease), metabolic diseases (atherosclerosis, diabetes and obesity) and major infections like human immunodeficiency virus infection. In view of this common etiology in these diseases, targeting the recruitment, activation and regulation of dysfunctional macrophages represents a promising therapeutic strategy. With the advancement of nanotechnology, development of nanomedicines to efficiently target dysfunctional macrophages can strengthen the effectiveness of therapeutics and improve clinical outcomes. This review discusses the specific roles of dysfunctional macrophages in various diseases and summarizes the latest advances in nanomedicine-based therapeutics and theranostics for treating diseases associated with dysfunctional macrophages.

MRI detection of endothelial cell inflammation using targeted superparamagnetic particles of iron oxide (SPIO)

Background

There is currently no clinical imaging technique available to assess the degree of inflammation associated with atherosclerotic plaques. This study aims to develop targeted superparamagnetic particles of iron oxide (SPIO) as a magnetic resonance imaging (MRI) probe for detecting inflamed endothelial cells.

Methods

The in vitro study consists of the characterisation and detection of inflammatory markers on activated endothelial cells by immunocytochemistry and MRI using biotinylated anti-P-selectin and anti-VCAM-1 (vascular cell adhesion molecule 1) antibody and streptavidin conjugated SPIO.

Results

Established an in vitro cellular model of endothelial inflammation induced with TNF-α (tumor necrosis factor alpha). Inflammation of endothelial cells was confirmed with both immunocytochemistry and MRI. These results revealed both a temporal and dose dependent expression of the inflammatory markers, P-selectin and VCAM-1, on exposure to TNF-α.

Conclusion

This study has demonstrated the development of an in vitro model to characterise and detect inflamed endothelial cells by immunocytochemistry and MRI. This will allow the future development of contrast agents and protocols for imaging vascular inflammation in atherosclerosis. This work may form the basis for a translational study to provide clinicians with a novel tool for the in vivo assessment of atherosclerosis.

Macrophages mediated diagnosis of rheumatoid arthritis using fibrin based magnetic nanoparticles as MRI contrast agents

BACKGROUND

A variety of bioimaging tools assists in the diagnosis and evaluation of rheumatoid arthritis (RA) and other osteoarthritis. However, detection of RA in the early stages by targeting its macrophages with suitable contrast agents will help in arresting the progression of the disease.

METHODS

In the present study, we investigated the effectiveness of using magnetic fibrin nanoparticles (MFNPs) conjugated with folic acid (FA-MFNPs) as a specific contrast agent to target the activated macrophages, which overexpress the folate receptors (FR) in the knee joints of rats with antigen-induced arthritis (AIA).

RESULTS

FA-MFNPs were spherical with an average size of 18.3±1.6nm. In vitro studies have shown effective internalization of FA-MFNPs into the Raw264.7 macrophage cells. In vivo studies were carried out by injecting FA-MFNPs intravenously into the arthritic rats. The results showed enhanced MR imaging in the synovium of arthritic joints. Prussian blue histological staining confirmed uptake of FA-MFNPs by macrophages in the synovial tissue.

CONCLUSION

The animal experiment results indicate that FA-MFNPs can be used as a specific MRI contrast agent in identifying phagocytic active macrophages in the synovial joints.

GENERAL SIGNIFICANCE

Blood is the precursor source for synthesising the fibrin-based iron oxide (magnetic) nanoparticles (MFNPs) with diameters between 12 and 15nm. It has excellent superparamagnetic behaviour, biocompatibility, osteogenic potency, hemocompatibility, and biodegradable properties. MFNPs-based nanocomposites might be a promising contrast agent for bioimaging.

Molecular Imaging of Vulnerable Atherosclerotic Plaques in Animal Models

Atherosclerosis is characterized by intimal plaques of the arterial vessels that develop slowly and, in some cases, may undergo spontaneous rupture with subsequent heart attack or stroke. Currently, noninvasive diagnostic tools are inadequate to screen atherosclerotic lesions at high risk of acute complications. Therefore, the attention of the scientific community has been focused on the use of molecular imaging for identifying vulnerable plaques. Genetically engineered murine models such as ApoE^−/− and ApoE^−/−Fbn1C1039G^+/− mice have been shown to be useful for testing new probes targeting biomarkers of relevant molecular processes for the characterization of vulnerable plaques, such as vascular endothelial growth factor receptor (VEGFR)-1, VEGFR-2, intercellular adhesion molecule (ICAM)-1, P-selectin, and integrins, and for the potential development of translational tools to identify high-risk patients who could benefit from early therapeutic interventions. This review summarizes the main animal models of vulnerable plaques, with an emphasis on genetically altered mice, and the state-of-the-art preclinical molecular imaging strategies.

Nanomedicine Meets microRNA: Current Advances in RNA-Based Nanotherapies for Atherosclerosis

Cardiovascular disease (CVD) accounts for almost half of all deaths worldwide and has now surpassed infectious disease as the leading cause of death and disability in developing countries. At present, therapies such as low-density lipoprotein-lowering statins and antihypertensive drugs have begun to bend the morality curve for coronary artery disease (CAD); yet, as we come to appreciate the more complex pathophysiological processes in the vessel wall, there is an opportunity to fine-tune therapies to more directly target mechanisms that drive CAD. MicroRNAs (miRNAs) have been identified that control vascular cell homeostasis,(1-3) lipoprotein metabolism,(4-9) and inflammatory cell function.(10) Despite the importance of these miRNAs in driving atherosclerosis and vascular dysfunction, therapeutic modulation of miRNAs in a cell- and context-specific manner has been a challenge. In this review, we summarize the emergence of miRNA-based therapies as an approach to treat CAD by specifically targeting the pathways leading to the disease. We focus on the latest development of nanoparticles (NPs) as a means to specifically target the vessel wall and what the future of these nanomedicines may hold for the treatment of CAD.

CTHRSSVVC Peptide as a Possible Early Molecular Imaging Target for Atherosclerosis

The purpose of our work was to select phages displaying peptides capable of binding to vascular markers present in human atheroma, and validate their capacity to target the vascular markers in vitro and in low-density lipoprotein receptor knockout (LDLr(-/-)) mouse model of atherosclerosis. By peptide fingerprinting on human atherosclerotic tissues, we selected and isolated four different peptides sequences, which bind to atherosclerotic lesions and share significant similarity to known human proteins with prominent roles in atherosclerosis. The CTHRSSVVC-phage peptide displayed the strongest reactivity with human carotid atherosclerotic lesions (p < 0.05), when compared to tissues from normal carotid arteries. This peptide sequence shares similarity to a sequence present in the fifth scavenger receptor cysteine-rich (SRCR) domain of CD163, which appeared to bind to CD163, and subsequently, was internalized by macrophages. Moreover, the CTHRSSVVC-phage targets atherosclerotic lesions of a low-density lipoprotein receptor knockout (LDLr(-/-)) mouse model of atherosclerosis in vivo to High-Fat diet group versus Control group. Tetraazacyclododecane-1,4,7,10-tetraacetic acid-CTHRSSVVC peptide (DOTA-CTHRSSVVC) was synthesized and labeled with (111)InCl₃ in >95% yield as determined by high performance liquid chromatography (HPLC), to validate the binding of the peptide in atherosclerotic plaque specimens. The results supported our hypothesis that CTHRSSVVC peptide has a remarkable sequence for the development of theranostics approaches in the treatment of atherosclerosis and other diseases.

Imaging Atherosclerosis

Advances in atherosclerosis imaging technology and research have provided a range of diagnostic tools to characterize high-risk plaque in vivo; however, these important vascular imaging methods additionally promise great scientific and translational applications beyond this quest. When combined with conventional anatomic- and hemodynamic-based assessments of disease severity, cross-sectional multimodal imaging incorporating molecular probes and other novel noninvasive techniques can add detailed interrogation of plaque composition, activity, and overall disease burden. In the catheterization laboratory, intravascular imaging provides unparalleled access to the world beneath the plaque surface, allowing tissue characterization and measurement of cap thickness with micrometer spatial resolution. Atherosclerosis imaging captures key data that reveal snapshots into underlying biology, which can test our understanding of fundamental research questions and shape our approach toward patient management. Imaging can also be used to quantify response to therapeutic interventions and ultimately help predict cardiovascular risk. Although there are undeniable barriers to clinical translation, many of these hold-ups might soon be surpassed by rapidly evolving innovations to improve image acquisition, coregistration, motion correction, and reduce radiation exposure. This article provides a comprehensive review of current and experimental atherosclerosis imaging methods and their uses in research and potential for translation to the clinic.

Detection and treatment of atherosclerosis using nanoparticles

Atherosclerosis is the key pathogenesis of cardiovascular disease, which is a silent killer and a leading cause of death in the United States. Atherosclerosis starts with the adhesion of inflammatory monocytes on the activated endothelial cells in response to inflammatory stimuli. These monocytes can further migrate into the intimal layer of the blood vessel where they differentiate into macrophages, which take up oxidized low-density lipoproteins and release inflammatory factors to amplify the local inflammatory response. After accumulation of cholesterol, the lipid-laden macrophages are transformed into foam cells, the hallmark of the early stage of atherosclerosis. Foam cells can die from apoptosis or necrosis, and the intracellular lipid is deposed in the artery wall forming lesions. The angiogenesis for nurturing cells is enhanced during lesion development. Proteases released from macrophages, foam cells, and other cells degrade the fibrous cap of the lesion, resulting in rupture of the lesion and subsequent thrombus formation. Thrombi can block blood circulation, which represents a major cause of acute heart events and stroke. There are generally no symptoms in the early stages of atherosclerosis. Current detection techniques cannot easily, safely, and effectively detect the lesions in the early stages, nor can they characterize the lesion features such as the vulnerability. While the available therapeutic modalities cannot target specific molecules, cells, and processes in the lesions, nanoparticles appear to have a promising potential in improving atherosclerosis detection and treatment via targeting the intimal macrophages, foam cells, endothelial cells, angiogenesis, proteolysis, apoptosis, and thrombosis. Indeed, many nanoparticles have been developed in improving blood lipid profile and decreasing inflammatory response for enhancing therapeutic efficacy of drugs and decreasing their side effects. WIREs Nanomed Nanobiotechnol 2017, 9:e1412. doi: 10.1002/wnan.1412 For further resources related to this article, please visit the WIREs website.

Molecular imaging of atherosclerosis with nanoparticle-based fluorinated MRI contrast agents

As atherosclerosis remains one of the most prevalent causes of patient mortality, the ability to diagnose early signs of plaque rupture and thrombosis represents a significant clinical need. With recent advances in nanotechnology, it is now possible to image specific molecular processes noninvasively with MRI, using various types of nanoparticles as contrast agents. In the context of cardiovascular disease, it is possible to specifically deliver contrast agents to an epitope of interest for detecting vascular inflammatory processes, which serve as predecessors to atherosclerotic plaque development. Herein, we review various applications of nanotechnology in detecting atherosclerosis using MRI, with an emphasis on perfluorocarbon nanoparticles and fluorine imaging, along with theranostic prospects of nanotechnology in cardiovascular disease.

Preclinical models of atherosclerosis. The future of Hybrid PET/MR technology for the early detection of vulnerable plaque

Cardiovascular diseases are the leading cause of death in developed countries. The aetiology is currently multifactorial, thus making them very difficult to prevent. Preclinical models of atherothrombotic diseases, including vulnerable plaque-associated complications, are now providing significant insights into pathologies like atherosclerosis, and in combination with the most recent advances in new non-invasive imaging technologies, they have become essential tools to evaluate new therapeutic strategies, with which can forecast and prevent plaque rupture. Positron emission tomography (PET)/computed tomography imaging is currently used for plaque visualisation in clinical and pre-clinical cardiovascular research, albeit with significant limitations. However, the combination of PET and magnetic resonance imaging (MRI) technologies is still the best option available today, as combined PET/MRI scans provide simultaneous data acquisition together with high quality anatomical information, sensitivity and lower radiation exposure for the patient. The coming years may represent a new era for the implementation of PET/MRI in clinical practice, but first, clinically efficient attenuation correction algorithms and research towards multimodal reagents and safety issues should be validated at the preclinical level.

In vivo MR and Fluorescence Dual-modality Imaging of Atherosclerosis Characteristics in Mice Using Profilin-1 Targeted Magnetic Nanoparticles

Aims: This study aims to explore non-invasive imaging of atherosclerotic plaque through magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) by using profilin-1 targeted magnetic iron oxide nanoparticles (PF₁-Cy5.5-DMSA-Fe₃O₄-NPs, denoted as PC-NPs) as multimodality molecular imaging probe in murine model of atherosclerosis. Methods and Results: PC-NPs were constructed by conjugating polyclonal profilin-1 antibody and NHS-Cy5.5 fluorescent dye to the surface of DMSA-Fe₃O₄-nanoparticles via condensation reaction. Murine atherosclerosis model was induced in apoE^-/- mice by high fat and cholesterol diet (HFD) for 16 weeks. The plaque areas in aortic artery were detected with Oil Red O staining. Immunofluorescent staining and Western blot analysis were applied respectively to investigate profilin-1 expression. CCK-8 assay and transwell migration experiment were performed to detect vascular smooth muscle cells (VSMCs) proliferation. In vivo MRI and NIRF imaging of atherosclerotic plaque were carried out before and 36 h after intravenous injection of PC-NPs. Oil Red O staining showed that the plaque area was significantly increased in HFD group (p<0.05). Immunofluorescence staining revealed that profilin-1 protein was highly abundant within plaque in HFD group and co-localized with α-smooth muscle actin. Profilin-1 siRNA intervention could inhibit VSMCs proliferation and migration elicited by ox-LDL (p<0.05). In vivo MRI and NIRF imaging revealed that PC-NPs accumulated in atherosclerotic plaque of carotid artery. There was a good correlation between the signals of MRI and ex vivo fluorescence intensities of NIRF imaging in animals with PC-NPs injection. Conclusion: PC-NPs is a promising dual modality imaging probe, which may improve molecular diagnosis of plaque characteristics and evaluation of pharmaceutical interventions for atherosclerosis.

Nanoparticle uptake by macrophages in vulnerable plaques for atherosclerosis diagnosis

The composition of atherosclerotic (AS) plaques is crucial concerning rupture, thrombosis and clinical events. Two plaque types are distinguished: stable and vulnerable plaques. Vulnerable plaques are rich in inflammatory cells, mostly only M1 macrophages, and are highly susceptible to rupture. These plaques represent a high risk particularly with the standard invasive diagnosis by coronary angiography. So far there are no non-invasive low-risk clinical approaches available to detect and distinguish AS plaque types in vivo. The perspective review introduces a whole work-flow for a novel approach for non-invasive detection and classification of AS plaques using the diffusion reflection method with gold nanoparticle loaded macrophages in combination with flow and image cytometric analysis for quality assurance. Classical biophotonic methods for AS diagnosis are summarized. Phenotyping of monocytes and macrophages are discussed for specific subset labelling by nanomaterials, as well as existing studies and first experimental proofs of concept for the novel approach are shown. In vitro and in vivo detection of NP loaded macrophages (MΦ). Different ways of MΦ labelling include (1) in vitro labelling in suspension (whole blood or buffy coat) or (2) labelling of short-term MΦ cultures with re-injection of MΦ-NP into the animal to detect migration of the cells in the plaques and (3) in vivo injection of NP into the organism.

Vascular and plaque imaging with ultrasmall superparamagnetic particles of iron oxide

Cardiovascular Magnetic Resonance (CMR) has become a primary tool for non-invasive assessment of cardiovascular anatomy, pathology and function. Existing contrast agents have been utilised for the identification of infarction, fibrosis, perfusion deficits and for angiography. Novel ultrasmall superparamagnetic particles of iron oxide (USPIO) contrast agents that are taken up by inflammatory cells can detect cellular inflammation non-invasively using CMR, potentially aiding the diagnosis of inflammatory medical conditions, guiding their treatment and giving insight into their pathophysiology. In this review we describe the utilization of USPIO as a novel contrast agent in vascular disease.

Multiscale investigation of USPIO nanoparticles in atherosclerotic plaques and their catabolism and storage in vivo

The storage and catabolism of Ultrasmall SuperParamagnetic Iron Oxide (USPIO) nanoparticles were analyzed through a multiscale approach combining Two Photon Laser Scanning Microscopy (TPLSM) and High-Resolution Transmission Electron Microscopy (HRTEM) at different times after intravenous injection in an atherosclerotic ApoE(-/-) mouse model. The atherosclerotic plaque features and the USPIO heterogeneous biodistribution were revealed down from organ's scale to subcellular level. The biotransformation of the nanoparticle iron oxide (maghemite) core into ferritin, the non-toxic form of iron storage, was demonstrated for the first time ex vivo in atherosclerotic plaques as well as in spleen, the iron storage organ. These results rely on an innovative spatial and structural investigation of USPIO's catabolism in cellular phagolysosomes. This study showed that these nanoparticles were stored as non-toxic iron compounds: maghemite oxide or ferritin, which is promising for MRI detection of atherosclerotic plaques in clinics using these USPIOs. From the Clinical Editor: Advance in nanotechnology has brought new contrast agents for clinical imaging. In this article, the authors investigated the use and biotransformation of Ultrasmall Super-paramagnetic Iron Oxide (USPIO) nanoparticles for analysis of atherosclerotic plagues in Two Photon Laser Scanning Microscopy (TPLSM) and High-Resolution Transmission Electron Microscopy (HRTEM). The biophysical data generated from this study could enable the possible use of these nanoparticles for the benefits of clinical patients.

Class A1 scavenger receptors in cardiovascular diseases

Class A1 scavenger receptors (SR-A1) are membrane glycoproteins that can form homotrimers. This receptor was originally defined by its ability to mediate the accumulation of lipids in macrophages. Subsequent studies reveal that SR-A1 plays critical roles in innate immunity, cell apoptosis and proliferation. This review highlights recent advances in understanding the structure, receptor pathway and regulation of SR-A1. Although its role in atherosclerosis is disputable, recent discoveries suggest that SR-A1 function in anti-inflammatory responses by promoting an M2 macrophage phenotype in cardiovascular diseases. Therefore, SR-A1 may be a potential target for therapeutic intervention of cardiovascular diseases.

Microwave-driven synthesis of bisphosphonate nanoparticles allows in vivo visualisation of atherosclerotic plaque

From flask to plaque characterisation in less than 4 hours. Extremely fast detection of atherosclerosis plaque by nanoparticle-based MRI.

'Ride on the ferrous wheel'--the cycle of iron in macrophages in health and disease

Iron homeostasis and macrophage biology are closely interconnected. On the one hand, iron exerts multiple effects on macrophage polarization and functionality. On the other hand, macrophages are central for mammalian iron homeostasis. The phagocytosis of senescent erythrocytes and their degradation by macrophages enable efficient recycling of iron and the maintenance of systemic iron balance. Macrophages express multiple molecules and proteins for the acquisition and utilization of iron and many of these pathways are affected by inflammatory signals. Of note, iron availability within macrophages has significant effects on immune effector functions and metabolic pathways within these cells. This review summarizes the physiological and pathophysiological aspects of macrophage iron metabolism and highlights its relevant consequences on immune function and in common diseases such as infection and atherosclerosis.

The effect of two novel amino acid-coated magnetic nanoparticles on survival in vascular endothelial cells, bone marrow stromal cells, and macrophages

Magnetic nanoparticles (MNPs) have been popularly used in many fields. Recently, many kinds of MNPs are modified as new absorbents, which have attracted considerable attention and are promising to be applied in waste water. In our previous study, we synthesized two novel MNPs surface-coated with glycine or lysine, which could efficiently remove many anionic and cationic dyes under severe conditions. It should be considered that MNP residues in water may exert some side effects on human health. In the present study, we evaluated the potential nanotoxicity of MNPs in human endothelial cells, macrophages, and rat bone marrow stromal cells. The results showed that the two kinds of nanoparticles were consistently absorbed into the cell cytoplasm. The concentration of MNPs@Gly that could distinctly decrease survival was 15 μg/ml in human umbilical vascular endothelial cells (HUVECs) or bone marrow stromal cells (BMSCs) and 10 μg/ml in macrophages. While the concentration of MNPs@Lys that obviously reduced viability was 15 μg/ml in HUVECs or macrophages and 50 μg/ml in BMSCs. Furthermore, cell nucleus staining and cell integrity assay indicated that the nanoparticles induced cell apoptosis, but not necrosis even at a high concentration. Altogether, these data suggest that the amino acid-coated magnetic nanoparticles exert relatively high cytotoxicity. By contrast, lysine-coated magnetic nanoparticles are more secure than glycine-coated magnetic nanoparticles.

Superparamagnetic Nanoparticles for Atherosclerosis Imaging

The production of magnetic nanoparticles of utmost quality for biomedical imaging requires several steps, from the synthesis of highly crystalline magnetic cores to the attachment of the different molecules on the surface. This last step probably plays the key role in the production of clinically useful nanomaterials. The attachment of the different biomolecules should be performed in a defined and controlled fashion, avoiding the random adsorption of the components that could lead to undesirable byproducts and ill-characterized surface composition. In this work, we review the process of creating new magnetic nanomaterials for imaging, particularly for the detection of atherosclerotic plaque, in vivo. Our focus will be in the different biofunctionalization techniques that we and several other groups have recently developed. Magnetic nanomaterial functionalization should be performed by chemoselective techniques. This approach will facilitate the application of these nanomaterials in the clinic, not as an exception, but as any other pharmacological compound.

Molecular imaging of macrophage enzyme activity in cardiac inflammation

Molecular imaging is highly advantageous as various insidious inflammatory events can be imaged in a serial and quantitative fashion. Combined with the conventional imaging modalities like computed tomography (CT), magnetic resonance (MR) and nuclear imaging, it helps us resolve the extent of ongoing pathology, quantify inflammation and predict outcome. Macrophages are increasingly gaining importance as an imaging biomarker in inflammatory cardiovascular diseases. Macrophages, recruited to the site of injury, internalize necrotic or foreign material. Along with phagocytosis, activated macrophages release proteolytic enzymes like matrix metalloproteinases (MMPs) and cathepsins into the extracellular environment. Pro-inflammatory monocytes and macrophages also induce tissue oxidative damage through the inflammatory enzyme myeloperoxidase (MPO). In this review we will highlight recent advances in molecular macrophage imaging. Particular stress will be given to macrophage functional and enzymatic activity imaging which targets phagocytosis, proteolysis and myeloperoxidase activity imaging.