Dextran-coated Superparamagnetic Iron Oxide Research Articles

First magnetic particle imaging to assess pulmonary vascular leakage in vivo in the acutely injured and fibrotic lung.

Increased pulmonary vascular permeability is a characteristic feature of lung injury. However, there are no established methods that allow the three-dimensional visualization and quantification of pulmonary vascular permeability in vivo. Evans blue extravasation test and total protein test of bronchoalveolar lavage fluid (BALF) are permeability assays commonly used in research settings. However, they lack the ability to identify the spatial and temporal heterogeneity of endothelial barrier disruption, which is typical in lung injuries. Magnetic resonance (MR) and near-infrared (NIR) imaging have been proposed to image pulmonary permeability, but suffer from limited sensitivity and penetration depth, respectively. In this study, we report the first use of magnetic particle imaging (MPI) to assess pulmonary vascular leakage noninvasively in vivo in mice. A dextran-coated superparamagnetic iron oxide (SPIO), synomag®, was employed as the imaging tracer, and pulmonary SPIO extravasation was imaged and quantified to evaluate the vascular leakage. Animal models of acute lung injury and pulmonary fibrosis (PF) were used to validate the proposed method. MPI sensitively detected the SPIO extravasation in both acutely injured and fibrotic lungs in vivo, which was confirmed by ex vivo imaging and Prussian blue staining. Moreover, 3D MPI illustrated the spatial heterogeneity of vascular leakage, which correlated well with CT findings. Based on the in vivo 3D MPI images, we defined the SPIO extravasation index (SEI) to quantify the vascular leakage. A significant increase in SEI was observed in the injured lungs, in consistent with the results obtained via ex vivo permeability assays. Overall, our results demonstrate that 3D quantitative MPI serves as a useful tool to examine pulmonary vascular integrity in vivo, which shows promise for future clinical translation.

Folate decorated dextran-coated magnetic nanoparticles for targeted delivery of ellipticine in cervical cancer cells

The dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs) grafted with foliate (FA) were prepared and used as a nanocarrier for ellipticine (ET) delivery in cervical cancer. In this work we prepared superparamagnetic iron oxide nanoparticles by pulsed laser ablation in liquid method. The formation of the SPION@DEX-ET-FA nanosystem was performed by a reverse microemulsion process. Dynamic light scattering (DLS), atomic force microscopy (AFM), and field emission scanning electron microscope (FESEM) were used to characteristic the morphological properties of the NPs. The appropriate impact of a therapeutic dose of SPION@DEX-ET-FA on both cancer and healthy cell lines was estimated using a 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) assay. The flow cytometry assays was used to evaluate the induction of apoptosis in Hela cervical cancer cells. The findings of the SPION@DEX-ET-FA formulated were spherical particles with an average size, polydispersity and a zeta potential of 101 ± 15.02 nm, 0.075 and −33.8 mV, respectively. The nanosystem displayed dose-dependent cytotoxic effects on Hela cells. The results showed that SPION@DEX-ET-FA retained antitumor activity and no adverse effects on healthy cells were found.

Biocompatibility of Dextran-Coated 30 nm and 80 nm Sized SPIONs towards Monocytes, Dendritic Cells and Lymphocytes

Dextran-coated superparamagnetic iron oxide nanoparticles (SPIONDex) of various sizes can be used as contrast agents in magnetic resonance imaging (MRI) of different tissues, e.g., liver or atherosclerotic plaques, after intravenous injection. In previous studies, the blood compatibility and the absence of immunogenicity of SPIONDex was demonstrated. The investigation of the interference of SPIONDex with stimulated immune cell activation is the aim of this study. For this purpose, sterile and endotoxin-free SPIONDex with different hydrodynamic sizes (30 and 80 nm) were investigated for their effect on monocytes, dendritic cells (DC) and lymphocytes in concentrations up to 200 µg/mL, which would be administered for use as an imaging agent. The cells were analyzed using flow cytometry and brightfield microscopy. We found that SPIONDex were hardly taken up by THP-1 monocytes and did not reduce cell viability. In the presence of SPIONDex, the phagocytosis of zymosan and E. coli by THP-1 was dose-dependently reduced. SPIONDex neither induced the maturation of DCs nor interfered with their stimulated maturation. The particles did not induce lymphocyte proliferation or interfere with lymphocyte proliferation after stimulation. Since SPIONDex rapidly distribute via the blood circulation in vivo, high concentrations were only reached locally at the injection site immediately after application and only for a very limited time. Thus, SPIONDex can be considered immune compatible in doses required for use as an MRI contrast agent.

Superparamagnetic Iron Oxide Nanoparticles and Curcumin Equally Promote Neuronal Branching Morphogenesis in the Absence of Nerve Growth Factor in PC12 Cells.

Regeneration of the damaged neurons in neurological disorders and returning their activities are two of the main purposes of neuromedicine. Combination use of specific nanoformulations with a therapeutic compound could be a good candidate for neuroregeneration applications. Accordingly, this research aims to utilize the combination of curcumin, as a neurogenesis agent, with dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs) to evaluate their effects on PC12 cells' neuronal branching morphogenesis in the absence of nerve growth factor. Therefore, the effects of each component alone and in combination form on the cytotoxicity, neurogenesis, and neural branching morphogenesis were evaluated using MTT assay, immunofluorescence staining, and inverted microscopy, respectively. Results confirmed the effectiveness of the biocompatible iron oxide nanoparticles (with a size of about 100 nm) in improving the percentage of neural branching (p < 0.01) in PC12 cells. In addition, the combination use of these nanoparticles with curcumin could enhance the effect of curcumin on neurogenesis (p < 0.01). These results suggest that SPIONs in combination with curcumin could act as an inducing factor on PC12 neurogenesis in the absence of nerve growth factor and could offer a novel therapeutic approach to the treatment of neurodegenerative diseases.

Optimizing Colloidal Stability and Transport of Polysaccharide-Coated Magnetic Nanoparticles for Reservoir Management: Effects of Ion Specificity

In this work we explore the mechanisms of ion-specific stabilization of a polysaccharide-based coating for colloidal nanomaterials used within the oil & gas industry. While nanotechnology has wide prevalence across multiple industries, its utility within this sector is largely undeveloped but has potential applications in areas including (but not limited to) exploration, drilling and production processes. For example, reservoir contrast agents in the form of superparamagnetic nanoparticles could be used to accurately determine the residual oil saturation distribution in a reservoir and thus advise enhanced oil recovery (EOR) efforts. However, deployment of such materials in oil reservoirs proves challenging in cases where high salinity subsurface environments induce nanoparticle aggregation, leading to loss of mobility. Here, we report the synthesis and characterization of dextran-coated superparamagnetic iron oxide nanoparticles (Dex-SPIONs), the colloidal stability of which was evaluated in various brine formulations at elevated temperatures. Initial dynamic light scattering (DLS) measurements reveal a lack of contingency between particle stability and total electrolyte concentration for samples comprised of synthetic seawater and low-salinity brine, the latter fluid of which possesses higher ionic strength yet preserves colloidal integrity to a much greater extent than its seawater counterpart. Further experiments point to a calcium (Ca2+) ion-specific stabilization effect wherein surface complexation of Ca2+ ions to the dextran periphery improves carbohydrate hydration and thus enhances colloidal stability. Ion selective electrode (ISE) measurements provide additional evidence of the Ca2+ - dextran binding interaction, the role of which also factors significantly into mitigation of polysaccharide degradation [as demonstrated through gel permeation chromatography (GPC)]. Finally, we assess the transport of Dex-SPIONs through porous media, including examination of retention properties with respect to variances in ionic composition.

Doxorubicin Loaded Dextran-coated Superparamagnetic Iron Oxide Na-noparticles with Sustained Release Property: Intracellular Uptake, Phar-macokinetics and Biodistribution Study.

Due to the short biological half-life and serious side effects (especially for heart and kidney), the application of Doxorubicin (Dox) in clinical therapy is strictly limited. To overcome these shortcomings, a novel sustained release formulation of doxorubicin-loaded dextran-coated superparamagnetic iron oxide nanoparticles (Dox-DSPIONs) was prepared. The purpose of this study was to evaluate the intracellular uptake behavior of Dox-DSPIONs and to investigate their pharmacokinetics and biodistribution properties. Confocal laser scanning microscopy was employed to study the intracellular uptake and release properties of Dox from Dox-DSPIONs in SMMC-7721 cells. Simple high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method was established to study the pharmacokinetics and biodistribution properties of Dox-DSPIONs in vivo after intravenous administration and compared with free Dox. Intracellular uptake experiment indicated that Dox could be released sustainedly from Dox-DSPIONs over time. The pharmacokinetics parameters displayed that the T1/2and AUC0-24h of Dox-DSPIONs were higher than those of free Dox, while the Cmax of Dox-DSPIONs was significantly lower than that of free drug. The biodistribution behaviors of the drug were altered by Dox-DSPIONs in mice, which showed obvious liver targeting, and significantly reduced the distribution of the drug in the heart and kidney. Dox-DSPIONs have the sustained-release property in vitro and in vivo, which could significantly prolong blood circulation time, improve bioavailability, and reduce the side effects of Dox. Therefore, the novel formulation of the Dox-DSPIONs has the potential as a promising drug delivery system in cancer therapy.

Magnetic Resonance Imaging of Tumor-Infiltrating Lymphocytes by Anti-CD3-Conjugated Iron Oxide Nanoparticles.

Immune checkpoint blockade, considered a revolutionary approach in cancer treatment, is only effective in patients with high tumor-infiltrating lymphocytes (TILs). This work aimed to investigate the feasibility of targeted contrast agent (CA) based on dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs-DEX) for TILs detection by magnetic resonance imaging (MRI) studies. To do so, we synthesized an MRI CA by conjugating SPIONs-DEX to an anti-CD3 monoclonal antibody via cyanogen bromide as a cross-linker. In vitro assessments demonstrated the higher labeling efficiency of the developed CA to CD3+ lymphocytes compared to SPIONs-DEX. In vivo MRI of a xenograft model of CD3+ lymphocytes revealed the significant signal loss after the intravenous injection of the bioconjugate by ∼34 % and 21 % in T2 *-weighted and T2 -weighted images, respectively. The histopathological evaluation of xenograft tumors confirmed the labeling of lymphocytes by the targeted CA. This approach could open up a new horizon in the non-invasive assessment of TILs to identify patients eligible for immunotherapy.

Complement opsonization of nanoparticles: Differences between humans and preclinical species

The complement system plays a key role in opsonization and immune clearance of engineered nanoparticles. Understanding the efficiency, inter-subject, and inter-strain differences of complement opsonization in preclinical species can help with translational nanomedicine development and improve our ability to model complement response in humans. Dextran-coated superparamagnetic iron oxide (SPIO) nanoparticles and a wide range of non-magnetic iron oxide nanoparticle formulations are widely used in magnetic resonance imaging and as clinically approved iron supplements. Previously we found that opsonization of SPIO nanoworms (NW) with the third complement protein (C3) proceeds mostly via the alternative pathway in humans, and via the lectin pathway in mice. Here, we studied the pathway and efficiency of opsonization of 106 nm SPIO NW with C3 in different preclinical species and commonly used laboratory strains. In sera of healthy human donors (n = 6), C3 opsonization proceeded exclusively through the alternative pathway. On the other hand, the C3 opsonization in dogs (6 breeds), rats (4 strains) and mice (5 strains) sera was either partially or completely dependent on the complement Ca2+-sensitive pathways (lectin and/or classical). Specifically, C3 opsonization in sera of Long Evans rat strain, and mouse strains widely used in nanomedicine research (BALB/c, C57BL/6 J, and A/J) was only through the Ca2+-dependent pathways. Dogs and humans had the highest between-subject variability in C3 opsonization levels, while rat and mouse sera showed the lowest between-strain variability. Furthermore, using a panel of SPIO nanoparticles of different sizes and dextran coatings, we found that the level of C3 opsonization (C3 molecules per milligram Fe) in human sera was lower than in animal sera. At the same time, there was a strong predictive value of complement opsonization in dog and rat sera; nanoparticles with higher C3 deposition in animals showed higher deposition in humans, and vice versa. Notably, the opsonization decreased with decreasing size in all sera. The studies highlight the importance of the consideration of species and strains for predicting human complement responses (opsonization) towards nanomedicines.

Synthesis of iron‐oxide magnetic nanoparticles coated with dextran of varied molecular mass using a facile ball‐milling method

A simple ball-milling method was implemented to prepare dextran-coated superparamagnetic iron oxide nanoparticles (dextran-coated SPIONs, DSPIONs) by coating dextran (molecular mass, M dextran, 10, 40, 70 and 100 kDa) onto nanoparticles, which synthesised with co-precipitation methods. The size, saturation magnetisation and hydrodynamic diameters of the DSPIONs, composed of Fe3O4 and γ-Fe2O3 proved by X-ray diffraction and Raman spectra, were 11–14 nm, 55–65 emu g−1 and 200–300 nm using transmission electron microscope, superconducting-quantum-interference-device magnetometer and dynamic light scattering devices, respectively. The characteristic lines of surface coating were revealed in attenuated-total-reflection Fourier-transform infrared spectra. The saturation magnetisation and surface coating percentage (thermogravimetric analysis) of the ball-milled DSPIONs were independent on M dextran. The results were different from the statistical data from previous studies: DSPIONs using increasing M dextran were accompanied by decreasing saturation magnetisation and increasing surface coating in conventional co-precipitation protocols. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay indicated the ball-milled DSPIONs exhibited low cytotoxicity in human hepatoma (SK-HEP1) cells, and the implementation of Prussian blue staining proved the DSPIONs were able to be uptaken by SK-HEP1. There was no obvious difference between the ball-milled DSPIONs with various M dextran. It demonstrated the ball milling process might be potential for SPION preparation in the biomedical field.

Magnetic targeted delivery of the SPIONs-labeled mesenchymal stem cells derived from human Wharton's jelly in Alzheimer's rat models

Alzheimer's disease (AD) as a progressive neurodegenerative disorder is one of the leading causes of death globally. Among all treatment approaches, mesenchymal stem cells (MSCs)-based therapy is a promising modality for neurological disorders including the AD. This study aimed to magnetically deliver human Wharton's jelly-derived MSCs (WJ-MSCs) toward the hippocampal area within the AD rat's brain and determine the effects of them in cognitive improvement. Rats were randomly divided into five groups as follow: vehicle-treated control, AD model (injection of 8 μg/kg of amyloid β 1–42), IV-NTC (treated with IV-injected Non-Targeted Cells), IV-TC (treated with IV-injected Targeted Cells), and ICV-NTC (treated with Intracerebroventricular-injected Non-Targeted Cells). WJ-MSCs were labeled with dextran-coated superparamagnetic iron oxide nanoparticles (dex-SPIONs, 50 μg/ml), by bio-mimicry method. SPIONs-labeled MSCs were highly prussian blue positive with an intracellular iron concentration of 2.9 ± 0.08 pg/cell, which were successfully targeted into the hippocampus of AD rats by a halbach magnet array as magnetic targeted cell delivery (MTCD) technique. Presence of SPIONs-labeled cells in hippocampal area was proved by magnetic resonance imaging (MRI) in which signal intensity was reduced by increasing the number of these cells. Behavioral examinations showed that WJ-MSCs caused memory and cognitive improvement. Also, histological assessments showed functional improvement of hippocampal cells by expression of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE). Overall, this study indicates MTCD approach as an alternative in MSC-based regenerative medicine because it approximately has the same results as invasive directly ICV-injection method has.

Effects of Dextran-Coated Superparamagnetic Iron Oxide Nanoparticles on Mouse Embryo Development, Antioxidant Enzymes and Apoptosis Genes Expression, and Ultrastructure of Sperm, Oocytes and Granulosa Cells.

BackgroundAlthough application of superparamagnetic iron oxide nanoparticles (SPIONs) in industry and medi- cine has increased, their potential toxicity in reproductive cells remains a controversial issue. This study was under- taken to address the response of sperm, oocyte, and resultant blastocyst to dextran-coated SPIONs (D-SPIONs) treat- ment during murine in vitro fertilization (IVF).Materials and Methods In this experimental study, murine mature oocytes were randomly divided into three groups: control, and low- and high-dose groups in which fertilization medium was mixed with 0, 50 and 250 µg/ml of D- SPIONs, respectively. Sperm and/or cumulus oocyte complexes (COCs) were cultured for 4 h in this medium for elec- tron microscopic analysis of sperm and COCs, and assessment of developmental competence and genes expression of Gpx1, Sod1, catalase, Bcl2l1 and Bax in the resultant blastocysts. ResultsUltrastructural study of sperm, oocyte, and granulosa showed destructed mitochondria and membranes in spermatozoa, vacuolated mitochondria and distorted cristae in oocytes, and disrupted nuclei and disorganized cell membranes in granulosa in a dose-dependent manner. Data showed that cleavage and blastocyst rates in the 250 µg/ml of D-SPIONs were significantly lower than in the control group (P<0.05). Gene expression of GPx1, Sod1, catalase, Bcl2l1 and Bax in resultant blastocysts of the high-dose group and catalase and Bax in resultant blastocysts of the low-dose group, was higher than the controls.ConclusionThere is considerable concern regarding D-SPIONs toxic effects on IVF, and mitochondrial and cell membrane damage in mouse spermatozoa and oocytes, which may be related to oxidative stress and apoptotic events.

Use of micro-PIXE for elemental characterization and iron uptake evaluation in zebrafish larvae exposed to iron oxide nanoparticles

We report on the evaluation of iron content and biodistribution in zebrafish larvae (Danio rerio) exposed to dextran-coated superparamagnetic iron oxide nanoparticles (SPION-DX) using the micro-PIXE technique. We compare results of elemental 2D maps and Fe quantification obtained from two different sample preparation procedures: one using sagittal slices prepared by cryo-sectioning and another using entire dehydrated larvae. Independently of the preparation method used, the Fe content in the tissues of exposed animals is significantly higher than in the controls, but the increase is not proportional to the exposure level. In addition, 2D elemental maps show a somewhat homogeneous Fe distribution in the larvae, with some samples showing a slight enhancement in Fe content near the gut. From the PIXE data a curve correlating the exposure (nanoparticle concentration in the fish water) to the iron content in the body was obtained, which shows a saturation trend towards high exposure doses.

MRI-Tracking of Dental Pulp Stem Cells In Vitro and In Vivo Using Dextran-Coated Superparamagnetic Iron Oxide Nanoparticles.

The aim of this study was to track dental pulp stem cells (DPSCs) labeled with dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs) using magnetic resonance imaging (MRI). Dental pulp was isolated from male Sprague Dawley rats and cultured in Dulbecco’s modified Eagle’s medium F12 (DMEM-F12) and 10% fetal bovine serum. Effects of SPIONs on morphology, viability, apoptosis, stemness, and osteogenic and adipogenic differentiation of DPSCs were assessed. Prussian blue staining and MRI were conducted to determine in vitro efficiency of SPIONs uptake by the cells. Both non-labeled and labeled DPSCs were adherent to culture plates and showed spindle-shape morphologies, respectively. They were positive for osteogenic and adipogenic induction and expression of cluster of differentiation (CD) 73 and CD90 biomarkers, but negative for expression of CD34 and CD45 biomarkers. The SPIONs were non-toxic and did not induce apoptosis in doses less than 25 mg/mL. Internalization of the SPIONs within the DPSCs was confirmed by Prussian blue staining and MRI. Our findings revealed that the MRI-based method could successfully monitor DPSCs labeled with dextran-coated SPIONs without any significant effect on osteogenic and adipogenic differentiation, viability, and stemness of DPSCs. We provided the in vitro evidence supporting the feasibility of an MRI-based method to monitor DPSCs labeled with SPIONs without any significant reduction in viability, proliferation, and differentiation properties of labeled cells, showing that internalization of SPIONs within DPSCs were not toxic at doses less than 25 mg/mL. In general, the SPION labeling does not seem to impair cell survival or differentiation. SPIONs are biocompatible, easily available, and cost effective, opening a new avenue in stem cell labeling in regenerative medicine.

P11.42 Magnetic targeting of the granzyme B functionalized nanoparticles for therapy of glioblastoma

Abstract BACKGROUND Magnetic drug targeting by employing external magnetic fields represents a promising approach for treatment of glioblastoma. To increase the anti-tumor therapeutic effect magnetic nanocarriers could be functionalized with tumor-targeting bioligands such as granzyme B (GrB). The serine protease GrB that is produced as an effector molecule by activated NK and T cells can induce specific tumor cell apoptosis. MATERIAL AND METHODS The targeting potential of the dextran-coated superparamagnetic iron oxide nanoparticles conjugated with GrB (GrB-SPIONs) was assessed in glioblastoma cells (U87, C6, GL261) by flow cytometry, confocal and electron microscopies. Magnetic field strength (320 mT) in the models of U87 glioblastoma in NMRI nu/nu mice and C6 glioma in Wistar rats was achieved by employing NdFeB cylindrical ferromagnet. The irradiation of the implanted tumors was performed using the CT-image guided Small Animal Radiation Research Platform (SARRP). Accumulation of the nanoparticles was assessed in paraffine-embedded specimens employing Prussian blues staining. Sections were additionally analyzed by IHC for apoptosis (caspase 3). RESULTS Synthesized GrB-SPIONs incorporated into the cytoplasm of tumor cells via the endolysosomal pathway and induced apoptosis in a dose-dependent manner. Intravenous injection of GrB-SPIONs resulted in the glioma-specific retention of the nanoparticles as was shown by high-field (11 T) magnetic resonance imaging and biodistribution studies (NLR-M2 measurements). Magnetic targeting of the nanoparticles in vivo drastically enhanced the accumulation of nanoparticles to the location of the magnet. Thus the local retention of nanoparticles was 12.3-fold higher as compared to application of GrB-SPIONs without external magnetic field. The presence of granzyme B on SPIONs has been shown to promote tumor cells death (IHC staining for caspase 3) and significantly increased overall survival. A combination of nanoparticle treatment with a single radiation dose (10 Gy) significantly prolonged the survival of rats as compared to animals treated only with magnetic targeting of GrB-SPIONs or radiotherapy alone (P&lt;0.001). CONCLUSION Single-agent therapy with GrB-SPIONs demonstrated an impressive increase in overall survival of tumor-bearing animals. Combinatorial regimen employing magnetic targeting and stereotactic radiotherapy further enhanced the therapeutic potential of magnetic conjugates.

Precision Nanomedicine Volume 1 Issue 1 Table of Contents

The inaugural issue is introduced by several editorials: "The Story of Precision Nanomedicine-the Journal", "Balancing Interests of Science, Scientists, and the Publishing Business", and "Improving Innovation in Nano-Healthcare Funding". The Clinical Editor's comments on research papers: Prec. Nanomed. 2018, Apr; 1(1):18-42. Extracellular vesicles (EVs) are involved in various biological processes such as cargo trafficking, cell-cell communication, and signal transduction. The advances in nanotechnology have enabled researchers to utilize EVs for potential use in clinical applications, within the so-called precision medicine approach. In this review article, the authors discuss the techniques used in EV isolation in length, together with their applications in clinical diagnosis and therapeutics. Prec. Nanomed. 2018 Apr;1(1):63-75. Due to potential hypersensitivity reactions to nanodrugs, thorough testing is required before these drugs can be used in the clinical setting. Here the authors provide a succinct review on the use of pigs as a reliable in-vivo model for pre-clinical drug testing. Prec. Nanomed. 2018 Apr;1(1):76-85. One of the ways that nanoparticles are cleared in the body is via Kupffer cells. The authors of the next paper tested the role of scavenger receptor SR-AI/II in the clearance of dextran superparamagnetic iron oxide (SPIO) Feridex-IV® and dextran-coated SPIO nanoworms (SPIO NWs). Results here show that multiple pathways and mechanisms exist in nanoparticle clearance. Thus, further understanding of nanoparticle clearance would be required to prolong in vivo half-life. Prec. Nanomed. 2018 Apr;1(1):43-62. Liposomes have been used in clinical practice for some years, this delivery system often result in significant systemic effects due to hypersensitivity reactions, via the activation of the complement system. The authors here show good biocompatibility of Rad-PC-Rad liposomes in terms of complement activation and pro-inflammatory cytokines production in-vitro.

Discrepancies in the in vitro and in vivo role of scavenger receptors in clearance of nanoparticles by Kupffer cells

Nanoparticles are recognized and cleared by Kupffer cells (KCs) in the liver. This process complicates the development of targeted nanoparticles because of significant reduction of number of nanoparticles that can reach target tissues. Macrophage scavenger receptor SR type AI/II is the central phagocytic receptor that has been shown to promote in vitro uptake of many nanoparticle types. In this paper, the authors set out to clarify the role of SR-AI/II in the in vivo liver clearance of 10kDa dextran superparamagnetic iron oxide (SPIO) Feridex-IV® and 20kDa dextran-coated SPIO nanoworms (SPIO NWs). Feridex showed efficient SR-AI/II-dependent uptake by isolated KCs in vitro, whereas SPIO NWs showed no uptake by KCs. Both Feridex and SPIO NWs showed a very short and nearly identical circulation half-life and efficient uptake by KCs in vivo. The SR-AI/II inhibitor, polyinosinic acid, prolonged the circulation half-life of both Feridex and SPIO NWs, but did not reduce the KC uptake. The circulation half-life and KC uptake of Feridex and SPIO NWs were identical in SR-AI/II-deficient mice and wild-type mice. These data suggest: (1) there is a limited correlation between in vitro and in vivo uptake mechanisms of nanoparticles in KCs; and (2) redundant, SR-AI/II independent mechanisms play a significant role in the nanoparticle recognition by KCs in vivo. Understanding the complexity of nanoparticle clearance assays and mechanisms is an important step to improving the design of “stealthy” nanoparticles.

Dextran-coated superparamagnetic iron oxide nanoparticles for magnetic resonance imaging: evaluation of size-dependent imaging properties, storage stability and safety.

BackgroundRising criticism of currently available contrast agents for magnetic resonance imaging, either due to their side effects or limited possibilities in terms of functional imaging, evoked the need for safer and more versatile agents. We previously demonstrated the suitability of novel dextran-coated superparamagnetic iron oxide nanoparticles (SPIONDex) for biomedical applications in terms of safety and biocompatibility.MethodsIn the present study, we investigated the size-dependent cross-linking process of these particles as well as the size dependency of their imaging properties. For the latter purpose, we adopted a simple and easy-to-perform experiment to estimate the relaxivity of the particles. Furthermore, we performed an extensive analysis of the particles’ storage stability under different temperature conditions, showing their superb stability and the lack of any signs of agglomeration or sedimentation during a 12 week period.ResultsIndependent of their size, SPIONDex displayed no irritation potential in a chick chorioallantoic membrane assay. Cell uptake studies of ultra-small (30 nm) SPIONDex confirmed their internalization by macrophages, but not by non-phagocytic cells. Additionally, complement activation-related pseudoallergy (CARPA) experiments in pigs treated with ultra-small SPIONDex indicated the absence of hypersensitivity reactions.ConclusionThese results emphasize the exceptional safety of SPIONDex, setting them apart from the existing SPION-based contrast agents and making them a very promising candidate for further clinical development.

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.

Non-immunogenic dextran-coated superparamagnetic iron oxide nanoparticles: a biocompatible, size-tunable contrast agent for magnetic resonance imaging.

Iron oxide-based contrast agents have been in clinical use for magnetic resonance imaging (MRI) of lymph nodes, liver, intestines, and the cardiovascular system. Superparamagnetic iron oxide nanoparticles (SPIONs) have high potential as a contrast agent for MRI, but no intravenous iron oxide-containing agents are currently approved for clinical imaging. The aim of our work was to analyze the hemocompatibility and immuno-safety of a new type of dextran-coated SPIONs (SPIONdex) and to characterize these nanoparticles with ultra-high-field MRI. Key parameters related to nanoparticle hemocompatibility and immuno-safety were investigated in vitro and ex vivo. To address concerns associated with hypersensitivity reactions to injectable nanoparticulate agents, we analyzed complement activation-related pseudoallergy (CARPA) upon intravenous administration of SPIONdex in a pig model. Furthermore, the size-tunability of SPIONdex and the effects of size reduction on their biocompatibility were investigated. In vitro, SPIONdex did not induce hemolysis, complement or platelet activation, plasma coagulation, or leukocyte procoagulant activity, and had no relevant effect on endothelial cell viability or endothelial–monocytic cell interactions. Furthermore, SPIONdex did not induce CARPA even upon intravenous administration of 5 mg Fe/kg in pigs. Upon SPIONdex administration in mice, decreased liver signal intensity was observed after 15 minutes and was still detectable 24 h later. In addition, by changing synthesis parameters, a reduction in particle size <30 nm was achieved, without affecting their hemo- and biocompatibility. Our findings suggest that due to their excellent biocompatibility, safety upon intravenous administration and size-tunability, SPIONdex particles may represent a suitable candidate for a new-generation MRI contrast agent.

Investigation of the genetic toxicity by dextran-coated superparamagnetic iron oxide nanoparticles (SPION) in HepG2 cells using the comet assay and cytokinesis-block micronucleus assay

Dextran-coated superparamagnetic iron oxide nanoparticles (dextran-SPION) have been commercially used for medical applications, such as magnetic imaging or targeted drug delivery, etc. Despite of this usefulness, there are continuous controversies on safety/toxicity of various SPIONs. In the case of dextran-SPION, the reported adverse effects include the cytotoxicity, oxidative stress and DNA damage in many cell types. In this study, the genetic toxicity of dextran-SPION in human hepatoma (HepG2) cells was evaluated with comet assay and cytokinesis-block micronucleus (CBMN) assay. Dextran-SPION did not inhibit cell proliferation as a function of dose and time. The comet assay indicated that 5 μg/mL of dextran-SPION induced a significant DNA strand breaks. A dose-dependent increase of the micronucleus (MN) frequency was observed in CBMN assay. The formation of intracellular reactive oxygen species (ROS) in HepG2 cells was induced by dextran-SPION. The results demonstrated that dextran-SPION exerted genetic toxicity in HepG2 cells. Also, it suggests that a mechanism by which dextran-SPION triggers the DNA and chromosomal damage in HepG2 cells may be via the generation of intracellular ROS.