Risk assessment of heavy metals in tuna from Japanese restaurants in the Republic of Korea.

Background: Studies on the risk of mercury (Hg) in Korean fishery products focus primarily on total Hg levels as opposed to methylmercury (MeHg) levels. None of the few studies on MeHg in tuna investigated tuna from Japanese restaurants. Few have evaluated lead (Pb), cadmium (Cd) and arsenic (As) in tuna. Thus, this study aimed to conduct a risk assessment by evaluating heavy metal concentrations in tuna from Japanese restaurants. Methods: Thirty-one tuna samples were collected from Japanese restaurants in the Republic of Korea. They were classified according to region and species. The concentration of heavy metals in the samples was analyzed using the Ministry of Food and Drug Safety Food Code method. The rate of exceedance of maximum residue levels (MRLs) and the risk compared to the provisional tolerable weekly intake (PTWI) set by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (%PTWI) were evaluated for risk assessment. Results: The mean of MeHg, Pb, Cd and As concentrations were 0.56 ± 1.47 mg/kg, 33.95 ± 3.74 µg/kg, 14.25 ± 2.19 µg/kg and 1.46 ± 1.89 mg/kg, respectively. No sample exceeded the MRLs of Pb and Cd, but 9.7% of the samples exceeded the MRL of MeHg. The %PTWIs of MeHg, Pb, Cd and As were 4.2037, 0.0162, 0.0244 and 1.1627, respectively. The %PTWI of MeHg by age group and sex was highest among men aged 19-29 years (10.6494), followed by men aged 30-49 years (7.2458) and women aged 19-29 years (4.8307). Conclusions: We found that 3 out of 31 samples exceeded the MRL of MeHg. The %PTWI of MeHg showed significant differences based on age and sex, and the value was likely to exceed a safe level depending on individuals' eating behaviors. Therefore, improved risk management for MeHg is required.

Curvature-sensing peptide inhibits tumour-derived exosomes for enhanced cancer immunotherapy.

Tumour-derived exosomes (T-EXOs) impede immune checkpoint blockade therapies, motivating pharmacological efforts to inhibit them. Inspired by how antiviral curvature-sensing peptides disrupt membrane-enveloped virus particles in the exosome size range, we devised a broadly useful strategy that repurposes an engineered antiviral peptide to disrupt membrane-enveloped T-EXOs for synergistic cancer immunotherapy. The membrane-targeting peptide inhibits T-EXOs from various cancer types and exhibits pH-enhanced membrane disruption relevant to the tumour microenvironment. The combination of T-EXO-disrupting peptide and programmed cell death protein-1 antibody-based immune checkpoint blockade therapy improves treatment outcomes in tumour-bearing mice. Peptide-mediated disruption of T-EXOs not only reduces levels of circulating exosomal programmed death-ligand 1, but also restores CD8+ T cell effector function, prevents premetastatic niche formation and reshapes the tumour microenvironment in vivo. Our findings demonstrate that peptide-induced T-EXO depletion can enhance cancer immunotherapy and support the potential of peptide engineering for exosome-targeting applications.

Dissolving microneedles for long-term storage and transdermal delivery of extracellular vesicles.

Extracellular vesicles (EVs) have shown great potential in disease diagnosis and treatment; however, their clinical applications remain challenging due to their unsatisfactory long-term stability and the lack of effective delivery strategies. In this study, we prepared human adipose stem cell-derived EV (hASC-EV)-loaded hyaluronic acid dissolving microneedles (EV@MN) to investigate the feasibility of EVs for their clinical applications. The biological activities of the EVs in this formulation were maintained for more than six months under mild storage conditions, especially at temperatures lower than 4 °C. Moreover, the EV@MN enabled precise and convenient intradermal delivery for sustained release of EVs in the dermis layer. Therefore, EV@MN significantly improved the biological functions of hASC-EVs on dermal fibroblasts by promoting syntheses of proteins for the extracellular matrix such as collagen and elastin, enhancing fibroblast proliferation, and regulating the phenotype of fibroblast, compared with other administration methods. This research revealed a possible and feasible formulation for the clinical application of EVs.

Recruitment of dendritic cells using 'find-me' signaling microparticles for personalized cancer immunotherapy.

Therapeutic cancer vaccines have attracted attention because of their potential to prime cytotoxic T cells, which are highly antigen (Ag)-specific, allowing personalized cancer immunotherapy. However, because of their low immunogenicity, cancer vaccines have been used in only a few types of cancers in clinics, primarily because of the poor Ag presentation of dendritic cells (DCs). To address these limitations of cancer vaccines, we show that 'find-me' signaling polymeric microparticles (F-PMs) bearing tumor lysate as an Ag can efficiently recruit DCs and facilitate antigen presentation. When subcutaneously injected into tumor-bearing mice, F-PMs significantly increased mature DCs in tumor-draining lymph nodes by eliciting adenosine triphosphate (ATP)-induced chemotaxis, resulting in high antitumor efficacy. CD8+ cytotoxic T cells were remarkably enriched in the tumor microenvironment following co-administration of an immune checkpoint inhibitor with F-PMs. We demonstrated that F-PMs elicit a robust antitumor immune response, which may provide a promising therapeutic option for cancer treatment.

Sulfisoxazole Elicits Robust Antitumour Immune Response Along with Immune Checkpoint Therapy by Inhibiting Exosomal PD-L1.

Despite their potent antitumor activity, clinical application of immune checkpoint inhibitors has been significantly limited by their poor response rates (<30%) in cancer patients, primarily due to immunosuppressive tumor microenvironments. As a representative immune escape mechanism, cancer-derived exosomes have recently been demonstrated to exhaust CD8+ cytotoxic T cells. Here, it is reported that sulfisoxazole, a sulfonamide antibacterial, significantly decreases the exosomal PD-L1 level in blood when orally administered to the tumor-bearing mice. Consequently, sulfisoxazole effectively reinvigorates exhausted T cells, thereby eliciting robust antitumor effects in combination with anti-PD-1 antibody. Overall, sulfisoxazole regulates immunosuppression through the inhibition of exosomal PD-L1, implying its potential to improve the response rate of anti-PD-1 antibodies.

Repurposing macitentan with nanoparticle modulates tumor microenvironment to potentiate immune checkpoint blockade.

Immune checkpoint therapy (ICT), which reinvigorates cytotoxic T cells, provides clinical benefits as an alternative to conventional cancer therapies. However, its clinical response rate is too low to treat an immune-excluded tumor, owing to the presence of abundant stromal elements impeding the penetration of immune cells. Here, we report that macitentan, a dual endothelin receptor antagonist approved by the FDA to treat pulmonary arterial hypertension, can be repositioned to modulate the desmoplastic tumor microenvironment (TME). In the 4T1 orthotopic tumor model, the polymeric nanoparticles bearing macitentan (M-NPs) prevent fibrotic progression by regulating the function of cancer-associated fibroblasts, attenuate the biogenesis of cancer cell-derived exosomes, and modulate the T cell subsets and distribution in TME. These results demonstrate that the M-NPs effectively reorganize the immunosuppressive TME by targeting the endothelin-1 axis and consequently exhibit synergistic antitumor effects in combination with ICT.

Reactive oxygen species-responsive dendritic cell-derived exosomes for rheumatoid arthritis.

Although tolerogenic dendritic cell-derived exosomes (TolDex) have emerged as promising therapeutics for rheumatoid arthritis (RA), their clinical applications have been hampered by their poor in vivo disposition after systemic administration. Herein, we report the development of stimuli-responsive TolDex that induces lesion-specific immunoregulation in RA. Responsiveness to reactive oxygen species (ROS), a physiological stimulus in the RA microenvironment, was conferred on TolDex by introducing a thioketal (TK) linker-embedded poly(ethylene glycol) (PEG) on TolDex surface via hydrophobic insertion. The detachment of PEG following overproduction of ROS facilitates the cellular uptake of ROS-responsive TolDex (TKDex) into activated immune cells. Notably, TolDex and TKDex downregulated CD40 in mature dendritic cells (mDCs) and regulated secretion of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) at the cellular level. In the collagen-induced arthritis (CIA) mouse model, PEG prolonged the blood circulation of TKDex following intravenous administration and enhanced their accumulation in the joints. In addition, TKDex decreased IL-6, increased transforming growth factor-ß, and induced the CD4+CD25+Foxp3+ regulatory T cells in CIA mice. Overall, ROS-responsive TolDex might have potential as therapeutic agents for RA. STATEMENT OF SIGNIFICANCE: Tolerogenic dendritic cell-derived exosomes (TolDex) are emerging immunoregulators of autoimmune diseases, including rheumatoid arthritis (RA). However, their lack of long-term stability and low targetability are still challenging. To overcome these issues, we developed reactive oxygen species (ROS)-responsive TolDex (TKDex) by incorporating the ROS-sensitive functional group-embedded poly(ethylene glycol) linker into the exosomal membrane of TolDex. Surface-engineered TKDex were internalized in mature DCs because of high ROS-sensitivity and enhanced accumulation in the inflamed joint in vivo. Further, for the first time, we investigated the potential mechanism of action of TolDex relevant to CD40 downregulation and attenuation of tumor necrosis factor (TNF)-α secretion. Our strategy highlighted the promising nanotherapeutic effects of stimuli-sensitive TolDex, which induces immunoregulation.

Recent Advances in Polymeric Nanomedicines for Cancer Immunotherapy.

Immunotherapy has emerged as a promising approach to treat cancer, since it facilitates eradication of cancer by enhancing innate and/or adaptive immunity without using cytotoxic drugs. Of the immunotherapeutic approaches, significant clinical potentials are shown in cancer vaccination, immune checkpoint therapy, and adoptive cell transfer. Nevertheless, conventional immunotherapies often involve immune-related adverse effects, such as liver dysfunction, hypophysitis, type I diabetes, and neuropathy. In an attempt to address these issues, polymeric nanomedicines are extensively investigated in recent years. In this review, recent advances in polymeric nanomedicines for cancer immunotherapy are highlighted and thoroughly discussed in terms of 1) antigen presentation, 2) activation of antigen-presenting cells and T cells, and 3) promotion of effector cells. Also, the future perspectives to develop ideal nanomedicines for cancer immunotherapy are provided.

Ultrasmall gold nanosatellite-bearing transformable hybrid nanoparticles for deep tumor penetration.

Since delivering drugs to an entire tumoral region leads to high therapeutic efficacy and good prognosis, achieving deep tumoral penetration of drugs is a major issue in cancer treatment. In this regard, conventional nanomedicines (>50 nm) have shown limitations in cancer therapy, primarily attributed to the heterogeneous distribution of drugs because of the physiological barrier of the tumor interstitial space. To address this issue, we prepared transformable hybrid nanoparticles (TNPs) consisting of a pH-responsive nanocarrier (PEG-PBAE) and doxorubicin (DOX)-conjugated ultrasmall (<3 nm) gold nanoparticles (nanosatellites). It has been shown that PEG-PBAE can serve as a reservoir for nanosatellites and release them in mildly acidic conditions (pH 6.5), mimicking the tumor microenvironment. When DOX-loaded TNPs (DOX-TNPs) were intravenously injected into tumor-bearing mice, they successfully accumulated and dissociated at the extracellular level of the tumor, leading to the disclosure of nanosatellites and free DOX. While the free DOX accumulated in tumor tissue near blood vessels, the deeply diffused nanosatellites were taken up by the tumor cell, followed by the release of DOX via cleavage of pH-responsive ester linkages in the nanosatellites at the intracellular level. Consequently, the DOX-TNPs effectively suppressed tumor growth through improved tumor penetration of DOX, suggesting their promising potential as a cancer nanomedicine. STATEMENT OF SIGNIFICANCE: Deep tumor penetration of anticancer drug is an important issue for high therapeutic efficacy. If the drugs cannot reach cancer cells in a sufficient concentration, their effectiveness will be limited. In this regard, conventional nanomedicine showed only modest therapeutic efficacy since they cannot deliver their payloads to the deep site of tumor tissue. This heterogeneous distribution of the drug is primarily attributed to the physiological barriers of the tumor microenvironment, including a dense extracellular matrix. To surmount this challenge, we developed tumor acidity-triggered transformable nanoparticles. By encapsulating doxorubicin-conjugated ultrasmall gold nanosatellites into the nanoparticles, the drug was not significantly bound to genetic materials, resulting in its minimal sequestration near the vasculature and deep tumor penetration. Our strategy could resolve not only the poor penetration issue of the drug but also its restricted tumor accumulation, suggesting the potential as an effective nanotherapeutics.

Anti-Trop2 antibody-conjugated bioreducible nanoparticles for targeted triple negative breast cancer therapy.

Trop2, a transmembrane glycoprotein, has emerged as a biomarker for targeted cancer therapy since it is overexpressed in 80% of triple negative breast cancer (TNBC) patients. For the site-specific delivery of the anticancer drug into TNBC, anti-Trop2 antibody-conjugated nanoparticles (ST-NPs) were prepared as the potential nanocarrier, composed of carboxymethyl dextran (CMD) derivatives with bioreducible disulfide bonds. Owing to its amphiphilicity, the CMD derivatives were self-assembled into nano-sized particles in an aqueous condition. Doxorubicin (DOX), chosen as a model anticancer drug, was effectively encapsulated into the nanoparticles. DOX-loaded ST-NPs (DOX-ST-NPs) rapidly released DOX in the presence of 10mM glutathione (GSH), whereas the DOX release is significantly retarded in the physiological condition (PBS, pH 7.4). Confocal microscopic images and flow cytometry analysis demonstrated that DOX-ST-NPs were selectively taken up by MDA-MB-231 as the representative Trop2-expressing TNBC cells. Consequently, DOX-ST-NPs exhibited higher toxicity to Trop2-positive MDA-MB-231 cancer cells, compared to DOX-loaded control nanoparticles without the disulfide bond or anti-Trop2 antibody. Overall, ST-NPs might be a promising carrier of DOX for targeted TNBC therapy.

Carboxymethyl dextran-based hypoxia-responsive nanoparticles for doxorubicin delivery.

In an attempt to develop the hypoxia-responsive nanoparticles for cancer therapy, a polymer conjugate, consisting of carboxymethyl dextran (CMD) and black hole quencher 3 (BHQ3), was prepared. The polymer conjugate can self-assemble into nanoparticles (CMD-BHQ3 NPs) under aqueous conditions. The anticancer drug, doxorubicin (DOX), was loaded in CMD-BHQ3 NPs to prepare DOX@CMD-BHQ3 NPs. The CMD-BHQ3 NPs released DOX in a sustained manner under physiological conditions, whereas the release rate of DOX remarkably increased under hypoxic conditions throughout the cleavage of the azo bond in BHQ3. In vitro cytotoxicity study revealed that DOX@CMD-BHQ3 NPs showed higher toxicity under hypoxic conditions than normoxic conditions. Confocal microscopic images indicated oxygen-dependent intracellular release of DOX from DOX@CMD-BHQ3. In vivo biodistribution study demonstrated that CMD-BHQ3 NPs were preferentially accumulated in the tumor after systemic administration into tumor-bearing mice. Overall, CMD-BHQ3 might be a promising carrier for selective drug release in the hypoxic tumor.

Tumor microenvironment-specific nanoparticles activatable by stepwise transformation.

In an attempt to develop the tumor-targeted nanocarrier which can surmount major challenges for in vivo application, we prepared tumor microenvironment-specific nanoparticles which can be sequentially activated at the extracellular and intracellular levels of tumor tissue by stepwise transformation. This polymeric nanoparticle has been prepared using an amphiphilic polyethyleneimine derivative with the pH-responsive charge-convertible moiety and the reduction-responsive crosslink. Once reaching the tumor tissue in vivo after systemic administration, the surface charge of this nanoparticle can be converted from negative to positive by recognizing the mildly acidic extracellular matrix of tumor, allowing for the enhanced cellular uptake. After the cellular uptake, the nanoparticle can selectively release the drug at the intracellular level since it has the chemically crosslinked core by the disulfide bond which is cleaved in intracellular reductive environment. The tumor microenvironment-specific nanoparticle shows the high tumor targetability and dramatically improves the antitumor efficacy of the drug.

Near-infrared light-triggered thermochemotherapy of cancer using a polymer-gold nanorod conjugate.

A biocompatible polymer-gold nanorod (P-AuNR) conjugate was developed as a thermo-chemotherapeutic nano-sized drug carrier for cancer therapy using near-infrared (NIR) light as an external trigger. The amphiphilic polymer, poly(ethylene glycol)-block-poly(caprolactone) (PEG-b-PCL) bearing a disulfide bond, was prepared using a facile synthetic route via copper(I)-free click chemistry and covalently linked to AuNR. The chemical structures and successful conjugation of PEG-b-PCL were analyzed using (1)H NMR and FT-IR. Doxorubicin (DOX), a hydrophobic anticancer drug, was effectively loaded into the hydrophobic PCL domain of P-AuNR through a simple dialysis method. P-AuNR showed longitudinal plasmon resonance absorption at the NIR region, thus generating heat under irradiation at 808 nm. Interestingly, exposure of P-AuNRs to NIR induced a structural change in the PCL block from a crystalline to an amorphous state, leading to the temporally controlled release of DOX. No significant release of DOX was observed from P-AuNRs under physiological conditions (pH 7.4), whereas the release rate of DOX was remarkably enhanced in response to NIR irradiation. In vitro cellular experiments to assess cytotoxicity and intracellular drug release behavior of DOX-P-AuNRs demonstrated that the release of DOX could be selectively regulated by NIR irradiation. Overall, DOX-P-AuNRs might have the potential to overcome the indiscriminate toxicity of free DOX.

A pH-responsive carboxymethyl dextran-based conjugate as a carrier of docetaxel for cancer therapy.

Although docetaxel is available for the treatment of various cancers, its clinical applications are limited by its poor water solubility and toxicity to normal cells, resulting in severe adverse effects. In this study, we synthesized a polymeric conjugate with an acid-labile ester linkage, consisting of carboxymethyl dextran (CMD) and docetaxel (DTX), as a potential anticancer drug delivery system. The conjugate exhibited sustained release of DTX in physiological buffer (pH 7.4), whereas its release rate increased remarkably under mildly acidic conditions (pH < 6.5), mimicking the intracellular environment. Cytotoxicity tests conducted in vitro demonstrated that the conjugate exhibited much higher toxicity to cancer cells under mildly acidic conditions than at physiological buffer (pH 7.4). These results implied that the ester linkage in the conjugate allowed for selective release of biologically active DTX under mildly acidic conditions. The in vivo biodistribution of a Cy5.5-labeled conjugate was observed using the noninvasive optical imaging technique after its systemic administration into tumor-bearing mice. The conjugate was effectively accumulated into the tumor site, which may have been because of an enhanced permeability and retention effect. In addition, in vivo antitumor efficacy of the conjugate was significantly higher than that of free DTX. Overall, the CMD-based conjugate might have promising potential as a carrier of DTX for cancer therapy.

Poly(ethylene glycol)-b-poly(lysine) copolymer bearing nitroaromatics for hypoxia-sensitive drug delivery.

Hypoxia occurs in a variety of pathological conditions including stroke, rheumatoid arthritis, atherosclerosis, and tumors. In this study, an amphiphilic block copolymer, composed of poly(ethylene glycol) as the hydrophilic block and poly(ε-(4-nitro)benzyloxycarbonyl-L-lysine) as the hydrophobic block, was prepared for hypoxia-sensitive drug delivery. Owing to its amphiphilic nature, the block copolymer formed micelles and encapsulated doxorubicin (DOX) in an aqueous condition. The DOX-loaded micelles exhibited rapid intracellular release of DOX under the hypoxic condition, implying high potential as a drug carrier for cancer therapy. STATEMENT OF SIGNIFICANCE: Hypoxia occurs in a variety of pathological conditions including stroke, rheumatoid arthritis, atherosclerosis, and tumors. In this study, we developed a novel type of hypoxia-sensitive polymeric micelles (HS-PMs) that can specifically release the drug under the hypoxic conditions. HS-PMs were prepared using poly(ethylene glycol) as the hydrophilic block and poly(ε-(4-nitro)benzyloxycarbonyl-L-lysine) as the hydrophobic block. Owing to its amphiphilic nature, the block copolymer formed micelles and encapsulated doxorubicin (DOX) in an aqueous condition. The DOX-loaded micelles exhibited rapid intracellular release of DOX under the hypoxic condition. Overall, it is evident that the HS-PMs prepared in this study have the potential to effectively deliver hydrophobic drugs into the hypoxic cells involved in various intractable diseases.

Recent developments in hyaluronic acid-based nanomedicine for targeted cancer treatment.

INTRODUCTION: Hyaluronic acid (HA) has emerged as a promising applicant for the tumor-targeted delivery of various therapeutic agents. Because of its biocompatibility, biodegradability and receptor-binding properties, HA has been extensively investigated as the drug delivery carrier. In this review, recent advances in HA-based nanomedicines are discussed. AREAS COVERED: This review focuses on HA-based nanomedicines for the diagnosis and treatment of cancer. In particular, recent advances in HA-drug conjugates and HA-based nanoparticles for small molecular drug delivery are discussed. The bioreducible HA conjugates for small interfering ribonucleic acid delivery have been also discussed. EXPERT OPINION: To develop a successful HA-based nanomedicine, it has to be prepared without significant deterioration of intrinsic property of HA. The chemical modification of HA with drugs or hydrophobic moieties may reduce the binding affinity of HA to the receptors. In addition, since the HA-based nanomedicines tend to accumulate in the liver after their systemic administration, new strategies to overcome this issue have to be developed.

Bioreducible shell-cross-linked hyaluronic acid nanoparticles for tumor-targeted drug delivery.

The major issues of self-assembled nanoparticles as drug carriers for cancer therapy include biostability and tumor-targetability because the premature drug release from and nonspecific accumulation of the drug-loaded nanoparticles may cause undesirable toxicity to normal organs and lower therapeutic efficacy. In this study, we developed robust and tumor-targeted nanocarriers based on an amphiphilic hyaluronic acid (HA)-polycaprolactone (PCL) block copolymer, in which the HA shell was cross-linked via a bioreducible disulfide linkage. Doxorubicin (DOX), chosen as a model anticancer drug, was effectively encapsulated into the nanoparticles with high drug loading efficiency. The DOX-loaded bioreducible HA nanoparticles (DOX-HA-ss-NPs) greatly retarded the drug release under physiological conditions (pH 7.4), whereas the drug release rate was markedly enhanced in the presence of glutathione, a thiol-containing tripeptide capable of reducing disulfide bonds in the cytoplasm. Furthermore, DOX-HA-ss-NPs could effectively deliver the DOX into the nuclei of SCC7 cells in vitro as well as to tumors in vivo after systemic administration into SCC7 tumor-bearing mice, resulting in improved antitumor efficacy in tumor-bearing mice. Overall, it was demonstrated that bioreducible shell-cross-linked nanoparticles could be used as a potential carrier for cancer therapy.

Hypoxia-responsive polymeric nanoparticles for tumor-targeted drug delivery.

Hypoxia is a condition found in various intractable diseases. Here, we report self-assembled nanoparticles which can selectively release the hydrophobic agents under hypoxic conditions. For the preparation of hypoxia-responsive nanoparticles (HR-NPs), a hydrophobically modified 2-nitroimidazole derivative was conjugated to the backbone of the carboxymethyl dextran (CM-Dex). Doxorubicin (DOX), a model drug, was effectively encapsulated into the HR-NPs. The HR-NPs released DOX in a sustained manner under the normoxic condition (physiological condition), whereas the drug release rate remarkably increased under the hypoxic condition. From in vitro cytotoxicity tests, it was found the DOX-loaded HR-NPs showed higher toxicity to hypoxic cells than to normoxic cells. Microscopic observation showed that the HR-NPs could effectively deliver DOX into SCC7 cells under hypoxic conditions. In vivo biodistribution study demonstrated that HR-NPs were selectively accumulated at the hypoxic tumor tissues. As consequence, drug-loaded HR-NPs exhibited high anti-tumor activity in vivo. Overall, the HR-NPs might have a potential as nanocarriers for drug delivery to treat hypoxia-associated diseases.

Dextran sulfate-coated superparamagnetic iron oxide nanoparticles as a contrast agent for atherosclerosis imaging.

The hallmark of atherosclerosis in its early pathogenic process is the overexpression of class A scavenger receptors (SR-A) by activated macrophages. In this study, dextran sulfate-coated superparamagnetic iron oxide nanoparticles (DS-SPIONs), as a magnetic resonance (MR) imaging contrast agent of atherosclerosis, was prepared via the facile co-precipitation method using a versatile double-hydrophilic block copolymer comprising of a DS segment (ligand for SR-A) and a poly(glyclerol methacrylate) segment (SPIONs surface-anchoring unit). The physicochemical properties of the DS-SPIONs were investigated using various instruments. DS-SPIONs exhibited high aqueous stability compared to dextran-coated SPIONs (Dex-SPIONs), which were used as controls. The cellular uptake behaviors of DS-SPIONs and Dex-SPIONs were evaluated using Prussian blue assay. Interestingly, the DS-SPIONs were effectively taken up by activated macrophages compared to Dex-SPIONs. However, the cellular uptake of DS-SPIONs by activated macrophages was remarkably reduced in the presence of free DS. These results suggest that activated macrophages internalize DS-SPIONs via receptor (SR-A)-mediated endocytosis. T2-weighted MR imaging of the cells demonstrated that activated macrophages treated with DS-SPIONs showed a significantly lower signal intensity compared to those treated with Dex-SPIONs. Overall, these results suggest that DS-SPIONs may be utilized as a potential contrast agent for atherosclerosis MR imaging.