A comprehensive literatures update of clinical researches of superparamagnetic resonance iron oxide nanoparticles for magnetic resonance imaging

The Transition from Metal-Based to Metal-Free Contrast Agents for T1 Magnetic Resonance Imaging Enhancement

Magnetic resonance imaging (MRI) has received significant attention as the noninvasive diagnostic technique for complex diseases. Image-guided therapeutic strategy for diseases such as cancer has also been at the front line of biomedical research, thanks to the innovative MRI, enhanced by the prior delivery of contrast agents (CAs) into patients' bodies through injection. These CAs have contributed a great deal to the clinical utility of MRI but have been based on metal-containing compounds such as gadolinium, manganese, and iron oxide. Some of these CAs have led to cytotoxicities such as the incurable Nephrogenic Systemic Fibrosis (NSF), resulting in their removal from the market. On the other hand, CAs based on organic nitroxide radicals, by virtue of their structural composition, are metal free and without the aforementioned drawbacks. They also have improved biocompatibility, ease of functionalization, and long blood circulation times, and have been proven to offer tissue contrast enhancement with longitudinal relaxivities comparable with those for the metal-containing CAs. Thus, this Review highlights the recent progress in metal-based CAs and their shortcomings. In addition, the remarkable goals achieved by the organic nitroxide radical CAs in the enhancement of MR images have also been discussed extensively. The focal point of this Review is to emphasize or demonstrate the crucial need for transition into the use of organic nitroxide radicals-metal-free CAs-as against the metal-containing CAs, with the aim of achieving safer application of MRI for early disease diagnosis and image-guided therapy.

Magnetic Iron Oxide Nanoparticle Labeling of Photoreceptor Precursors for Magnetic Resonance Imaging

IMPACT STATEMENT

This study describes the methods and results of superparamagnetic iron oxide nanoparticle (SPION) labeling and magnetic resonance imaging (MRI) tracking of human embryonic stem cell-derived photoreceptor precursors transplanted into the subretinal space of Royal College of Surgeons rats. SPION labeling and MRI tracking provide information about the biodistribution of transplanted photoreceptor precursors, which is necessary for improving the functional benefits of cell therapy for degenerative retinal diseases.

Intravital assessment of angioarchitecture in rat hepatocellular nodules using in vivo fluorescent microscopy

Background

To prospectively evaluate the stepwise changes that occur in intra-nodular microvessels and microcirculation during the carcinogenesis process of hepatocellular nodules by using in vivo fluorescent microscopy, and to compare these with pathological changes.

Methods

Forty-five 10-week-old male Wistar rats received drinking water containing N-nitrosomorpholine at 10 mg/100 mL for 18weeks to develop multiple hepatocellular carcinomas (HCC) and dysplastic nodules (DN) in the liver; meanwhile, the non-lesion liver tissues become fibrotic. The microvascular morphological change and hemodynamic change of two lesion areas (HCC or DN) and one non-lesion area in each rat were observed with in vivo fluorescent microscope. After in vivo microscopy, 90 nodules and 45 non-lesion liver tissues that were observed were removed for pathological study. The microvessel density (MVD), branch density (BD), and cell density (CD) of these lesions were compared with the Kruskal-Wallis test and Mann-Whitney test, with an overall statistical significance of 0.05.

Results

The intra-nodular microvessels appeared tortuous, with irregular branching and abrupt diameter changes to form irregular convoluted networks in the HCC. This was distinctly different from the appearance of DN and non-lesion liver parenchyma. The MVD and BD of HCC were less than that of the DN and non-lesion liver parenchyma (P<0.01), and the BD of DN was also less than that of the non-lesion liver parenchyma (P<0.05). However, the MVD of the DN was similar to that of the non-lesion liver parenchyma (P>0.05). The CD of HCC was more than that of the DN and non-lesion liver parenchyma (P<0.05), and the CD of DN was also more than that of the non-lesion liver parenchyma (P<0.05).

Conclusions

Concurrent with the carcinogenesis process of the hepatocellular nodule, both the intra-nodular microvascular morphology and hemodynamics were stepwise changed, and the number of the intravascular lumen of intranodular microvessels decreased due to the infiltration and compression of intra-nodular parenchymal cells.

Impact of Locally Administered Carboxydextran-Coated Super-Paramagnetic Iron Nanoparticles on Cellular Immune Function

Interstitially administered iron oxide particles are currently used for interoperative localization of sentinel lymph nodes (LNs) in cancer staging. Several studies have described concerns regarding the cellular accumulation of iron oxide nanoparticles relating them to phenotype and function deregulation of macrophages, impairing their ability to mount an appropriate immune response once an insult is present. This study aims to address what phenotypic and functional changes occur during lymphatic transit and accumulation of these particles. Data show that 60 nm carboxydextran-coated iron nanoparticles use a noncellular mechanism to reach the draining LNs and that their accumulation in macrophages induces transient phenotypic and functional changes. Nevertheless, macrophages recover their baseline levels of response within 7 days, and are still able to mount an appropriate response to bacterially induced inflammation.

Nanocarrier-based systems for targeted and site specific therapeutic delivery

Systemic drug delivery methods such as oral or parenteral administration of free drugs possess relatively low treatment efficiency and marked adverse side effects. The use of nanoparticles for drug delivery in most cases substantially enhances drug efficacy, improves pharmacokinetics and drug release and limits their side effects. However, further enhancement in drug efficacy and significant limitation of adverse side effects can be achieved by specific targeting of nanocarrier-based delivery systems especially in combination with local administration. The present review describes major advantages and limitations of organic and inorganic nanocarriers or living cell-based drug and nucleic acid delivery systems. Among these, different nanoparticles, supramolecular gels, therapeutic cells as living drug carriers etc. have emerged as a new frontier in modern medicine.

Combining magnetic hyperthermia and dual T1/T2 MR imaging using highly versatile iron oxide nanoparticles

Magnetic hyperthermia and magnetic resonance imaging (MRI) are two of the most important biomedical applications of magnetic nanoparticles (MNPs). However, the design of MNPs with good heating performance for hyperthermia and dual T1/T2 contrast for MRI remains a considerable challenge. In this work, ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) are synthesized through a simple one-step methodology. A post-synthetic purification strategy has been implemented in order to separate discrete nanoparticles from aggregates and unstable nanoparticles, leading to USPIONs that preserve chemical and colloidal stability for extended periods of time. The optimized nanoparticles exhibit high saturation magnetization and show good heating efficiency in magnetic hyperthermia experiments. Remarkably, the evaluation of the USPIONs as MRI contrast agents revealed that the nanoparticles are also able to provide significant dual T1/T2 signal enhancement. These promising results demonstrate that USPIONs are excellent candidates for the development of theranostic nanodevices with potential application in both hyperthermia and dual T1/T2 MR imaging.

Locating the Site of Neuropathic Pain In Vivo Using MMP-12-Targeted Magnetic Nanoparticles

Neuropathic pain remains underrecognised and ineffectively treated in chronic pain sufferers. Consequently, their quality of life is considerably reduced, and substantial healthcare costs are incurred. The anatomical location of pain must be identified for definitive diagnosis, but current neuropsychological tools cannot do so. Matrix metalloproteinases (MMP) are thought to maintain peripheral neuroinflammation, and MMP-12 is elevated particularly in such pathological conditions. Magnetic resonance imaging (MRI) of the peripheral nervous system has made headway, owing to its high-contrast resolution and multiplanar features. We sought to improve MRI specificity of neural lesions, by constructing an MMP-12-targeted magnetic iron oxide nanoparticle (IONP). Its in vivo efficiency was evaluated in a rodent model of neuropathic pain, where the left lumbar 5 (L5) spinal nerve was tightly ligated. Spinal nerve ligation (SNL) successfully induced mechanical allodynia, and thermal hyperalgesia, in the left hind paw throughout the study duration. These neuropathy characteristics were absent in animals that underwent sham surgery. MMP-12 upregulation with concomitant macrophage infiltration, demyelination, and elastin fibre loss was observed at the site of ligation. This was not observed in spinal nerves contralateral and ipsilateral to the ligated spinal nerve or uninjured left L5 spinal nerves. The synthesised MMP-12-targeted magnetic IONP was stable and nontoxic in vitro. It was administered onto the left L5 spinal nerve by intrathecal injection, and decreased magnetic resonance (MR) signal was observed at the site of ligation. Histology analysis confirmed the presence of iron in ligated spinal nerves, whereas iron was not detected in uninjured left L5 spinal nerves. Therefore, MMP-12 is a potential biomarker of neuropathic pain. Its detection in vivo, using IONP-enhanced MRI, may be further developed as a tool for neuropathic pain diagnosis and management.

A scientometric analysis on hepatocellular carcinoma magnetic resonance imaging research from 2008 to 2017

Background

With the development of new magnetic resonance imaging (MRI) techniques, an increasing number of articles have been published regarding hepatocellular carcinoma magnetic resonance imaging (HCCMRI) in the past decade. However, few studies have statistically analyzed these published articles. In this study, we aim to systematically evaluate the scientific outcomes of HCCMRI research and explore the research hotspots from 2008 to 2017.

Methods

The included articles regarding HCCMRI research from 2008 to 2017 were downloaded from the Web of Science Core Collection and verified by two experienced radiologists. Excel 2016 was used to analyze the literature data, including the publication years and journals. CiteSpace V was used to perform co-occurrence analyses for authors, countries/regions and institutions and to generate the related collaboration network maps. Reference co-citation analysis (RCA) and burst keyword detection were also performed using CiteSpace V to explore the research hotspots in the past decade.

Results

A total of 835 HCCMRI articles published from 2008 to 2017 were identified. Journal of Magnetic Resonance Imaging published the most articles (79 publications, 9.46%). Extensive cooperating relationship were observed among countries/regions and among authors. South Korea had the most publications (199 publications, 21.82%), followed by the United States of America (USA) (190 publications, 20.83%), Japan (162 publications, 17.76%), and the People's Republic of China (148 publications, 16.23%). Among the top 10 co-cited authors, Bruix J (398 citations) was ranked first, followed by Llovet JM (235 citations), Kim YK (170 citations) and Forner A (152 citations). According to the RCA, ten major clusters were explored over the last decade; "LI-RADS data system" and "microvascular invasion" (MVI) were the two most recent clusters. Forty-seven burst keywords with the highest citation strength were detected over time. Of these keywords, "microvascular invasion" had the highest strength in the last 3 years. The LI-RADS has been constantly updated with the latest edition released in July 2018. However, the LI-RADS still has limitations in identifying certain categories of lesions by conceptual and non-quantitative probabilistic methods. Plenty of questions still need to be further answered such as the difference of diagnostic efficiency of each major/ancillary imaging features. Preoperative prediction of MVI of HCC is very important to therapeutic decision-making. Some parameters of Gd-EOB-DTPA-enhanced MRI were found to be useful in prediction of MVI, however, with a high specificity but a very low sensitivity. Comprehensive predictive model incorporating both imaging and clinical variables may be the more preferable in prediction of MVI of HCC.

Conclusions

HCCMRI-related publications displayed a gradually increasing trend from 2008 to 2017. The USA has a central position in collaboration with other countries/regions, while South Korea contributed the most in the number of publications. Of the ten major clusters identified in the RCA, the two most recent clusters were "LI-RADS data system" and "microvascular invasion", indicative of the current HCCMRI research hotspots.

A T1/T2 dual functional iron oxide MRI contrast agent with super stability and low hypersensitivity benefited by ultrahigh carboxyl group density

Clinically acceptable safety and efficacy are the most important issues for the design and synthesis of iron oxide MRI contrast agents. In order to meet the practical requirements, a kind of low molecular weight PAA-coated Fe₃O₄ nanoparticle (CS015) with super colloidal stability and low hypersensitivity benefitting from an ultrahigh carboxyl group density was developed in this study. The composition and physicochemical properties of the particles were characterized by TEM, XRD, FTIR and TGA. The ultrahigh density of COOH on the particles (33 COOH per nm²) was verified while a core size of 5.1 nm and a dynamic diameter of 41 nm with a narrow distribution were also achieved. The particles still showed excellent dispersity and stability even after a spray-drying or freeze-drying process, exposure to high temperature sterilized conditions and long-term storage. The nanoparticles could quickly capture iron ions in bulk solution which was confirmed by ITC results, and the bioactive iron concentration of CS015 was greatly decreased (0.54 ± 0.05 mg L^-1) compared to that of commercially available ferumoxytol, iron sucrose and VSOP. Free iron ion release was 1120 times lower than the toxic concentration of iron. An excellent biocompatibility of CS015 with no obvious cytotoxicity and low risk of hypersensitivity has been manifested by cytotoxicity experiments and a passive cutaneous anaphylaxis test. The T₁ and T₂-weighted MRI contrast effects both in vitro and in vivo have also been verified which made CS015 a potential dual MRI contrast agent. Furthermore, theoretically calculated conformation was speculated and all the advantages mentioned above were benefited from the three dimensional brush-like texture of CS015. Therefore, these merits make the CS015 nanoplatform highly suitable in diagnostic applications as a MRI contrast agent.

Nanotechnology in the diagnosis and treatment of lung cancer

Lung cancer is an umbrella term for a subset of heterogeneous diseases that are collectively responsible for the most cancer-related deaths worldwide. Despite the tremendous progress made in understanding lung tumour biology, advances in early diagnosis, multimodal therapy and deciphering molecular mechanisms of drug resistance, overall curative outcomes remain low, especially in metastatic disease. Nanotechnology, in particular nanoparticles (NPs), continue to progressively impact the way by which tumours are diagnosed and treated. The unique physicochemical properties of materials at the nanoscale grant access to a diverse molecular toolkit that can be manipulated for use in respiratory oncology. This realisation has resulted in several clinically approved NP formulations and many more in clinical trials. However, NPs are not a panacea and have yet to be utilised to maximal effect in lung cancer, and medicine in a wider context. This review serves to: describe the complexity of lung cancer, the current diagnostic and therapeutic environment, and highlight the recent advancements of nanotechnology based approaches in diagnosis and treatment of respiratory malignancies. Finally, a brief outlook on the future directions of nanomedicine is provided; presently the full potential of the field is yet to be realised. By gleaning lessons and integrating advancements from neighbouring disciplines, nanomedicine can be elevated to a position where the current barriers that stymie full clinical impact are lifted.

Targeted T1 Magnetic Resonance Imaging Contrast Enhancement with Extraordinarily Small CoFe2O4 Nanoparticles

Extraordinarily small (2.4 nm) cobalt ferrite nanoparticles (ESCIoNs) were synthesized by a one-pot thermal decomposition approach to study their potential as magnetic resonance imaging (MRI) contrast agents. Fine size control was achieved using oleylamine alone, and annular dark-field scanning transmission electron microscopy revealed highly crystalline cubic spinel particles with atomic resolution. Ligand exchange with dimercaptosuccinic acid rendered the particles stable in physiological conditions with a hydrodynamic diameter of 12 nm. The particles displayed superparamagnetic properties and a low r₂/ r₁ ratio suitable for a T₁ contrast agent. The particles were functionalized with bile acid, which improved biocompatibility by significant reduction of reactive oxygen species generation and is a first step toward liver-targeted T₁ MRI. Our study demonstrates the potential of ESCIoNs as T₁ MRI contrast agents.

Systemic exposure to a single dose of ferucarbotran aggravates neuroinflammation in a murine model of experimental autoimmune encephalomyelitis

Background

Medicinal preparations of iron oxide nanoparticles (IONPs) have been used as MRI contrast agents for the diagnosis of hepatic tumors and the assessment of neuroinflammation and blood–brain barrier integrity. However, it remains mostly unclear whether exposure to IONPs affects neuroinflammation under disease conditions. The present study aims to investigate the impact of IONPs on autoimmune-mediated neuroinflammation using a murine model of experimental autoimmune encephalomyelitis (EAE) that mimics human multiple sclerosis.

Methods

Mice were either left untreated or immunized with myelin oligodendrocyte glyco-protein on day 0 followed by two injections of pertussis toxin for EAE induction. The EAE mice were intravenously administered with a single dose of the carboxydextran-coated IONPs, ferucarbotran (20 mg Fe/kg) and/or saline (as vehicle) on day 18. Symptoms of EAE were daily monitored until the mice were killed on day 30. Tissue sections of the brain and spinal cord were prepared for histopathological examinations. Iron deposition, neuron demyelination and inflammatory cell infiltration were examined using histochemical staining. The infiltration of microglial and T cells, and cytokine expression were examined by immunohistochemical staining and/or reverse transcription polymerase chain reaction (RT-PCR).

Results

Iron deposition was detected in both the brain and spinal cord of EAE mice 3 days post-ferucarbotran treatment. The clinical and pathological scores of EAE, percentage of myelin loss and infiltration of inflammatory cells into the spinal cord were significantly deteriorated in EAE mice treated with ferucarbotran. Furthermore, ferucarbotran treatment increased the number of CD3⁺, Iba-1⁺, IL-6⁺, Iba-1⁺TNF-α⁺ and CD3⁺IFN-γ⁺ cells in the spinal cord of EAE mice.

Conclusion

A single exposure to ferucarbotran exacerbated neuroinflammation and disease severity of EAE, which might be attributed to the enhanced activation of microglia and T cells. These results demonstrated that the pro-inflammatory effect of ferucarbotran on the central nervous system is closely associated with the deterioration of autoimmunity.

Clinical Trials of Thermosensitive Nanomaterials: An Overview

Currently, we are facing increasing demand to develop efficient systems for the detection and treatment of diseases that can realistically improve distinct aspects of healthcare in our society. Sensitive nanomaterials that respond to environmental stimuli can play an important role in this task. In this manuscript, we review the clinical trials carried out to date on thermosensitive nanomaterials, including all those clinical trials in hybrid nanomaterials that respond to other stimuli (e.g., magnetic, infrared radiation, and ultrasound). Specifically, we discuss their use in diagnosis and treatment of different diseases. At present, none of the existing trials focused on diagnosis take advantage of the thermosensitive characteristics of these nanoparticles. Indeed, almost all clinical trials consulted explore the use of Ferumoxytol as a current imaging test enhancer. However, the thermal property is being further exploited in the field of disease treatment, especially for the delivery of antitumor drugs. In this regard, ThermoDox®, based on lysolipid thermally sensitive liposome technology to encapsulate doxorubicin (DOX), is the flagship drug. In this review, we have evidenced the discrepancy existing between the number of published papers in thermosensitive nanomaterials and their clinical use, which could be due to the relative novelty of this area of research; more time is needed to validate it through clinical trials. We have no doubt that in the coming years there will be an explosion of clinical trials related to thermosensitive nanomaterials that will surely help to improve current treatments and, above all, will impact on patients' quality of life and life expectancy.

Targeted Drug Delivery and Image-Guided Therapy of Heterogeneous Ovarian Cancer Using HER2-Targeted Theranostic Nanoparticles

Cancer heterogeneity and drug resistance limit the efficacy of cancer therapy. To address this issue, we have developed an integrated treatment protocol for effective treatment of heterogeneous ovarian cancer. Methods: An amphiphilic polymer coated magnetic iron oxide nanoparticle was conjugated with near infrared dye labeled HER2 affibody and chemotherapy drug cisplatin. The effects of the theranostic nanoparticle on targeted drug delivery, therapeutic efficacy, non-invasive magnetic resonance image (MRI)-guided therapy, and optical imaging detection of therapy resistant tumors were examined in an orthotopic human ovarian cancer xenograft model with highly heterogeneous levels of HER2 expression. Results: We found that systemic delivery of HER2-targeted magnetic iron oxide nanoparticles carrying cisplatin significantly inhibited the growth of primary tumor and peritoneal and lung metastases in the ovarian cancer xenograft model in nude mice. Differential delivery of theranostic nanoparticles into individual tumors with heterogeneous levels of HER2 expression and various responses to therapy were detectable by MRI. We further found a stronger therapeutic response in metastatic tumors compared to primary tumors, likely due to a higher level of HER2 expression and a larger number of proliferating cells in metastatic tumor cells. Relatively long-time retention of iron oxide nanoparticles in tumor tissues allowed interrogating the relationship between nanoparticle drug delivery and the presence of resistant residual tumors by in vivo molecular imaging and histological analysis of the tumor tissues. Following therapy, most of the remaining tumors were small, primary tumors that had low levels of HER2 expression and nanoparticle drug accumulation, thereby explaining their lack of therapeutic response. However, a few residual tumors had HER2-expressing tumor cells and detectable nanoparticle drug delivery but failed to respond, suggesting additional intrinsic resistant mechanisms. Nanoparticle retention in the small residual tumors, nevertheless, produced optical signals for detection by spectroscopic imaging. Conclusion: The inability to completely excise peritoneal metastatic tumors by debulking surgery as well as resistance to chemotherapy are the major clinical challenges for ovarian cancer treatment. This targeted cancer therapy has the potential for the development of effective treatment for metastatic ovarian cancer.

Iron oxide nanoparticles: Diagnostic, therapeutic and theranostic applications

Many different iron oxide nanoparticles have been evaluated over the years, for a wide variety of biomedical applications. We here summarize the synthesis, surface functionalization and characterization of iron oxide nanoparticles, as well as their (pre-) clinical use in diagnostic, therapeutic and theranostic settings. Diagnostic applications include liver, lymph node, inflammation and vascular imaging, employing mostly magnetic resonance imaging but recently also magnetic particle imaging. Therapeutic applications encompass iron supplementation in anemia and advanced cancer treatments, such as modulation of macrophage polarization, magnetic fluid hyperthermia and magnetic drug targeting. Because of their properties, iron oxide nanoparticles are particularly useful for theranostic purposes. Examples of such setups, in which diagnosis and therapy are intimately combined and in which iron oxide nanoparticles are used, are image-guided drug delivery, image-guided and microbubble-mediated opening of the blood-brain barrier, and theranostic tissue engineering. Together, these directions highlight the versatility and the broad applicability of iron oxide nanoparticles, and indicate the integration in future medical practice of multiple iron oxide nanoparticle-based materials.

Iron oxide nanoparticles as multimodal imaging tools

In medicine, obtaining simply a resolute and accurate image of an organ of interest is a real challenge.

Iron oxide nanoparticles: Diagnostic, therapeutic and theranostic applications

Many different iron oxide nanoparticles have been evaluated over the years, for a wide variety of biomedical applications. We here summarize the synthesis, surface functionalization and characterization of iron oxide nanoparticles, as well as their (pre-) clinical use in diagnostic, therapeutic and theranostic settings. Diagnostic applications include liver, lymph node, inflammation and vascular imaging, employing mostly magnetic resonance imaging but recently also magnetic particle imaging. Therapeutic applications encompass iron supplementation in anemia and advanced cancer treatments, such as modulation of macrophage polarization, magnetic fluid hyperthermia and magnetic drug targeting. Because of their properties, iron oxide nanoparticles are particularly useful for theranostic purposes. Examples of such setups, in which diagnosis and therapy are intimately combined and in which iron oxide nanoparticles are used, are image-guided drug delivery, image-guided and microbubble-mediated opening of the blood-brain barrier, and theranostic tissue engineering. Together, these directions highlight the versatility and the broad applicability of iron oxide nanoparticles, and indicate the integration in future medical practice of multiple iron oxide nanoparticle-based materials.

Sub-acute intravenous exposure to Fe2O3 nanoparticles does not alter cognitive performances and catecholamine levels, but slightly disrupts plasma iron level and brain iron content in rats

Engineered nanomaterials are used in various applications due to their particular properties. Among them, Iron Oxide Nanoparticles (Fe₂O₃-NPs) are used in Biomedicine as theranostic agents i.e. contrast agents in Magnetic Resonance Imaging and cancer treatment. With the increasing production and use of these Fe₂O₃-NPs, there is an evident raise of Fe₂O₃-NPs exposure and subsequently a higher risk of adverse outcomes for the environment and Human. In the present paper, we investigated the effects of an intravenous daily Fe₂O₃-NPs exposure on Wistar rat for one week. As results, we showed that several hematological parameters and transaminase (ALT and AST) levels as well as organ histology remained unchanged in treated rats. Neither the catecholamine levels nor the emotional behavior and learning / memory capacities of rats were impacted by the sub-acute intravenous exposure to Fe₂O₃-NPs. However, iron level in plasma and iron content homeostasis in brain were disrupted after this exposure. Thus, our results demonstrated that Fe₂O₃-NPs could have transient effects on rat but the intravenous route is still safer that others which is encouraging for their use in medical and/or biological applications.

Simultaneous use of magnetic method in localization of impalpable breast cancer and sentinel lymph nodes detection: initial experience

Aim: In this study we used a new technology for localization of non-palpable breast tumors using a small steel marker in conjunction of sentinel nodes (SLNs) detection through injection of SPIO nanoparticles; both detected through a magnetic probe. Materials & methods: Ten patients with biopsy-proven nonpalpable invasive breast carcinoma or premalignant lesions eligible for SLNs biopsy were enrolled in this study. Results: All tumors were removed with safe surgical margins. The mean nodal detection rate was 3.4 nodes per patient. No interferences in magnetic probe measurements due to the presence of both markers in the same breast were observed. Conclusion: Simultaneous use of the magnetic method in localization of impalpable breast tumors and SNs detection makes breast surgery convenient.

Molecular Imaging of a New Multimodal Microbubble for Adhesion Molecule Targeting

Introduction

Inflammation is an important risk-associated component of many diseases and can be diagnosed by molecular imaging of specific molecules. The aim of this study was to evaluate the possibility of targeting adhesion molecules on inflammation-activated endothelial cells and macrophages using an innovative multimodal polyvinyl alcohol-based microbubble (MB) contrast agent developed for diagnostic use in ultrasound, magnetic resonance, and nuclear imaging.

Methods

We assessed the binding efficiency of antibody-conjugated multimodal contrast to inflamed murine or human endothelial cells (ECs), and to peritoneal macrophages isolated from rats with peritonitis, utilizing the fluorescence characteristics of the MBs. Single-photon emission tomography (SPECT) was used to illustrate ^99mTc-labeled MB targeting and distribution in an experimental in vivo model of inflammation.

Results

Flow cytometry and confocal microscopy showed that binding of antibody-targeted MBs to the adhesion molecules ICAM-1, VCAM-1, or E-selectin, expressed on cytokine-stimulated ECs, was up to sixfold higher for human and 12-fold higher for mouse ECs, compared with that of non-targeted MBs. Under flow conditions, both VCAM-1- and E-selectin-targeted MBs adhered more firmly to stimulated human ECs than to untreated cells, while VCAM-1-targeted MBs adhered best to stimulated murine ECs. SPECT imaging showed an approximate doubling of signal intensity from the abdomen of rats with peritonitis, compared with healthy controls, after injection of anti-ICAM-1-MBs.

Conclusions

This novel multilayer contrast agent can specifically target adhesion molecules expressed as a result of inflammatory stimuli in vitro, and has potential for use in disease-specific multimodal diagnostics in vivo using antibodies against targets of interest.

New Strategies and In Vivo Monitoring Methods for Stem Cell-Based Anticancer Therapies

Cancer is a devastating disease and the second cause of death in the developed world. Despite significant advances in recent years, such as the introduction of targeted therapies such as receptor tyrosine kinase inhibitors and immunotherapy, current approaches are insufficient to stop the advance of the disease and many cancer types remain largely intractable. In this review, we describe the latest and most revolutionary stem cell-based approaches for the treatment of cancer. We also summarize the emerging imaging modalities being applied for monitoring anticancer stem cell therapy success and discuss the implications of these novel technologies for precision medicine.

Polymer coated gold-ferric oxide superparamagnetic nanoparticles for theranostic applications

BACKGROUND

Engineered inorganic nanoparticles (NPs) are essential components in the development of nanotechnologies. For applications in nanomedicine, particles need to be functionalized to ensure a good dispersibility in biological fluids. In many cases however, functionalization is not sufficient: the particles become either coated by a corona of serum proteins or precipitate out of the solvent. We show that by changing the coating of magnetic iron oxide NPs using poly-L-lysine (PLL) polymer the colloidal stability of the dispersion is improved in aqueous solutions including water, phosphate buffered saline (PBS), PBS with 10% fetal bovine serum (FBS) and cell culture medium, and the internalization of the NPs toward living mammalian cells is profoundly affected.

METHODS

A multifunctional magnetic NP is designed to perform a near-infrared (NIR)-responsive remote control photothermal ablation for the treatment of breast cancer. In contrast to the previously reported studies of gold (Au) magnetic (Fe3O4) core-shell NPs, a Janus-like nanostructure is synthesized with Fe3O4 NPs decorated with Au resulting in an approximate size of 60 nm mean diameter. The surface of trisoctahedral Au-Fe3O4 NPs was coated with a positively charged polymer, PLL to deliver the NPs inside cells. The PLL-Au-Fe3O4 NPs were characterized by transmission electron microscopy (TEM), XRD, FT-IR and dynamic light scattering (DLS). The unique properties of both Au surface plasmon resonance and superparamagnetic moment result in a multimodal platform for use as a nanothermal ablator and also as a magnetic resonance imaging (MRI) contrast agent, respectively. Taking advantage of the photothermal therapy, PLL-Au-Fe3O4 NPs were incubated with BT-474 and MDA-MB-231 breast cancer cells, investigated for the cytotoxicity and intracellular uptake, and remotely triggered by a NIR laser of ~ 808 nm (1 W/cm2 for 10 min).

RESULTS

The PLL coating increased the colloidal stability and robustness of Au-Fe3O4 NPs (PLL-Au-Fe3O4) in biological media including cell culture medium, PBS and PBS with 10% fetal bovine serum. It is revealed that no significant (< 10%) cytotoxicity was induced by PLL-Au-Fe3O4 NPs itself in BT-474 and MDA-MB-231 cells at concentrations up to 100 μg/ml. Brightfield microscopy, fluorescence microscopy and TEM showed significant uptake of PLL-Au-Fe3O4 NPs by BT-474 and MDA-MB-231 cells. The cells exhibited 40 and 60% inhibition in BT-474 and MDA-MB-231 cell growth, respectively following the internalized NPs were triggered by a photothermal laser using 100 μg/ml PLL-Au-Fe3O4 NPs. The control cells treated with NPs but without laser showed < 10% cell death compared to no laser treatment control CONCLUSION: Combined together, the results demonstrate a new polymer gold superparamagnetic nanostructure that integrates both diagnostics function and photothermal ablation of tumors into a single multimodal nanoplatform exhibiting a significant cancer cell death.

SPIO-loaded nanostructured lipid carriers as liver-targeted molecular T2-weighted MRI contrast agent

Background

Superparamagnetic iron oxide (SPIO) acts as a negative contrast agent in magnetic resonance imaging (MRI), and is widely used in clinical applications, including the diagnosis of hepatic diseases. Hepatocyte-targeted magnetic resonance contrast agents (MRCAs) can provide useful information for evaluating hepatic diseases. We prepared targeted magnetic nanostructured lipid carriers (MNLCs) to enhance the hepatocytes targeting efficiency.

Methods

In vitro characterizations of MNLCs were determined by transmission electron microscopy (TEM). The cytotoxicity assay of the MNLCs was measured by methyl tetrazolium (MTT) method. The uptaken study was measured by confocal microscopy, flow cytometry and MRI in vitro. The enhanced liver-targeting efficiency of MNLCs was measured by fluorescence imaging and MRI in vivo.

Results

Gal-NLC-SPIO was prepared successfully. The cytotoxicity assay of the MNLCs demonstrated that the MNLC had relatively low cytotoxicity and high biocompatibility for LO2 cells. More importantly, we confirmed that Gal-NLC-SPIO had greater uptake by LO2 cells than Gal-NLC-SPIO/PEG and free Gal in vitro. A liver distribution study of MNLCs in normal mice demonstrated that the fluorescent signal values to livers of the Gal-NLC-SPIO were significantly stronger than those of NLC-SPIO and Gal-NLC-SPIO/PEG. The liver targeting efficiency of Gal-NLC-SPIO was confirmed both in vitro and in vivo.

Conclusions

We successfully developed liver-targeting MNLCs, which showed accurate hepatocytes targeting, and thus have the potential to be a new MRI contrast agent to help the diagnosis of liver diseases.

Design and synthesis of magnetic nanoparticles for biomedical diagnostics

Sensitive and quantitative characterization of clinically relevant biomarkers can facilitate disease diagnosis and treatment evaluation. Magnetic nanomaterials and their biosensing strategies have recently received considerable attention. Magnetic signals experience little interference from native biological background as most biological molecules have negligible magnetic susceptibilities and thus appear transparent to external magnetic fields. Because of this unique property, magnetic sensing can be applied to both in vivo deep tissue imaging as well as ex vivo point-of-care diagnostics. To exploit this mode of magnetic detection, new advancements in both magnetic material syntheses and sensing technologies have been made. This review focuses on recent developments of magnetic nanomaterials as image contrast agents and diagnostic sensors. These developments have not only enabled precise control of magnetic nanomaterial properties but also expanded the reach of magnetic detection for biomedical diagnostics.

Current aspects in treatment of breast cancer based of nanodrug delivery systems and future prospects

Breast cancer is one of the most common diseases worldwide. The risk of getting this disease in female is 30% and the mortality rate is 14%. The breast cancer treatment is based on surgery, chemotherapy and radiotherapy. However, an effective treatment method has not been developed. The main cause of failure in the treatment is cancer stem cells metastasis and chemo-resistance. The use of nanocarrier systems against breast cancer stem cells has great importance. Not only advantages of polymeric drug delivery systems are increasing the stability and reduce the side effects of drugs, but also they have disadvantages such as biocompatibility and long-term potential safety. However, in recent years, studies on exosomes provide several advantages. Exosomes usage as nanocarrier do not cause immunological reactions also the drug effectively transport into the cytosol of targeted cell and have more stability characteristics. Although there are studies about various nanocarrier systems in literature against breast cancer but in general, we have not found any review that brings them together and develops a systematic approach to solving the problem. This review mentions prospective new strategies based on various nanocarrier systems and emphasize the importance of exosome based on drug delivery systems in the treatment of breast cancer.

AGuIX® from bench to bedside-Transfer of an ultrasmall theranostic gadolinium-based nanoparticle to clinical medicine

AGuIX^® are sub-5 nm nanoparticles made of a polysiloxane matrix and gadolinium chelates. This nanoparticle has been recently accepted in clinical trials in association with radiotherapy. This review will summarize the principal preclinical results that have led to first in man administration. No evidence of toxicity has been observed during regulatory toxicity tests on two animal species (rodents and monkeys). Biodistributions on different animal models have shown passive uptake in tumours due to enhanced permeability and retention effect combined with renal elimination of the nanoparticles after intravenous administration. High radiosensitizing effect has been observed with different types of irradiations in vitro and in vivo on a large number of cancer types (brain, lung, melanoma, head and neck…). The review concludes with the second generation of AGuIX nanoparticles and the first preliminary results on human.

Magnetic Targeting of Growth Factors Using Iron Oxide Nanoparticles

Growth factors play an important role in nerve regeneration and repair. An attractive drug delivery strategy, termed “magnetic targeting”, aims to enhance therapeutic efficiency by directing magnetic drug carriers specifically to selected cell populations that are suitable for the nervous tissues. Here, we covalently conjugated nerve growth factor to iron oxide nanoparticles (NGF-MNPs) and used controlled magnetic fields to deliver the NGF–MNP complexes to target sites. In order to actuate the magnetic fields a modular magnetic device was designed and fabricated. PC12 cells that were plated homogenously in culture were differentiated selectively only in targeted sites out of the entire dish, restricted to areas above the magnetic “hot spots”. To examine the ability to guide the NGF-MNPs towards specific targets in vivo, we examined two model systems. First, we injected and directed magnetic carriers within the sciatic nerve. Second, we injected the MNPs intravenously and showed a significant accumulation of MNPs in mouse retina while using an external magnet that was placed next to one of the eyes. We propose a novel approach to deliver drugs selectively to injured sites, thus, to promote an effective repair with minimal systemic side effects, overcoming current challenges in regenerative therapeutics.

Imaging of Human Insulin Secreting Cells with Gd-DOTA-P88, a Paramagnetic Contrast Agent Targeting the Beta Cell Biomarker FXYD2γa

Non-invasive imaging and quantification of human beta cell mass remains a major challenge. We performed pre-clinical in vivo validation of a peptide previously discovered by our group, namely, P88 that targets a beta cell specific biomarker, FXYD2γa. We conjugated P88 with DOTA and then complexed it with GdCl₃ to obtain the MRI (magnetic resonance imaging) contrast agent (CA) Gd-DOTA-P88. A scrambled peptide was used as a negative control CA, namely Gd-DOTA-Scramble. The CAs were injected in immunodeficient mice implanted with EndoC-βH1 cells, a human beta cell line that expresses FXYD2γa similarly to primary human beta cells. The xenograft-bearing mice were analyzed by MRI. At the end, the mice were euthanized and the CA biodistribution was evaluated on the excised tissues by measuring the Gd concentration with inductively coupled plasma mass spectrometry (ICP-MS). The MRI and biodistribution studies indicated that Gd-DOTA-P88 accumulates in EndoC-βH1 xenografts above the level observed in the background tissue, and that its uptake is significantly higher than that observed for Gd-DOTA-Scramble. In addition, the Gd-DOTA-P88 showed good xenograft-to-muscle and xenograft-to-liver uptake ratios, two potential sites of human islets transplantation. The CA shows good potential for future use to non-invasively image implanted human beta cells.

Biomineralized hybrid nanoparticles for imaging and therapy of cancers

In this review, we describe the research trends of hybrid nanocarriers developed based on a biomimetic mineralization process, and their recent applications in imaging and therapy of cancers. Organic-inorganic hybrid nanostructures formed by diverse biomimetic mineralization approaches are briefly reviewed, and particularly, the biomedical applications of these hybrid nanocarriers for the diagnosis and therapy of cancers are discussed. Biomineralization is an important process in which living organisms produce biominerals, such as calcium phosphate (CaP), calcium carbonate (CaCO3), and silica (SiO2), to strengthen their tissues, as found in the formation of bone and teeth. Introducing the artificial biomimetic mineralization process to nanobiotechnology has inspired researchers to develop smart stimuli-responsive nanoparticles for multiple purposes, such as improved therapeutic activity and activatable imaging of cancers.

A GPC3-specific aptamer-mediated magnetic resonance probe for hepatocellular carcinoma

Purpose

To construct and test a hepatocellular carcinoma (HCC)-targeted magnetic resonance probe based on a glypican-3 (GPC3)-specific aptamer (AP613-1) with ultrasmall superpara-magnetic iron oxide (USPIO).

Methods

Oleic acid-coated USPIO nanoparticles were modified with amino polyethylene glycol on the surface. Amino groups of the USPIO nanoparticles were reacted with the carboxyl group of 5' carboxyl-modified AP613-1, forming an aptamer-mediated USPIO (Apt-USPIO) probe. The material characterization of this probe including transmission electron microscopy (TEM), zeta potential, dynamic laser scattering, and magnetic behavior was carried out. The targeting efficiency and magnetic resonance imaging (MRI) performance of Apt-USPIO were evaluated both in vitro and in vivo with USPIO alone as a control. The cytotoxicity and bio-compatibility of Apt-USPIO and USPIO were analyzed by cell counting kit-8 tests in vitro and animal experiments in vivo.

Results

TEM imaging revealed that the Apt-USPIO nanoparticles were spherical in shape and well dispersed. Specific uptake of Apt-USPIO in Huh-7 cells could be observed using the Prussian blue staining test; however, no uptake of USPIO could be found. In vitro phantom T₂-weighted MRI showed a significant decrease of the signal intensity in Apt-USPIO-incubated Huh-7 cells compared to USPIO-incubated Huh-7 cells. In vivo T₂-weighted MRI showed significantly negative enhancement in the Huh-7 tumors enhanced with Apt-USPIO, whereas no enhancement was found with USPIO alone. Excellent biocompatibility of Apt-USPIO and USPIO was also demonstrated.

Conclusion

In this study, a molecular MRI probe which was highly specific to GPC3 on HCC was successfully prepared. Our results validated the targeted imaging effect of this Apt-USPIO probe in vivo for GPC3-expressing HCCs in xenograft mice.

Micellar Iron Oxide Nanoparticles Coated with Anti-Tumor Glycosides

The synthesis procedure of nanoparticles based on thermal degradation produces organic solvent dispersible iron oxide nanoparticles (OA-IONP) with oleic acid coating and unique physicochemical properties of the core. Some glycosides with hydrophilic sugar moieties bound to oleyl hydrophobic chains have antimitotic activity on cancer cells but reduced in vivo applications because of the intrinsic low solubility in physiological media, and are prone to enzymatic hydrolysis. In this manuscript, we have synthetized and characterized OA-IONP-based micelles encapsulated within amphiphilic bioactive glycosides. The glycoside-coated IONP micelles were tested as Magnetic Resonance Imaging (MRI) contrast agents as well as antimitotics on rat glioma (C6) and human lung carcinoma (A549) cell lines. Micelle antimitotic activity was compared with the activity of the corresponding free glycosides. In general, all OA-IONP-based micellar formulations of these glycosides maintained their anti-tumor effects, and, in one case, showed an unusual therapeutic improvement. Finally, the micelles presented optimal relaxometric properties for their use as T2-weighed MRI contrast agents. Our results suggest that these bioactive hydrophilic nano-formulations are theranostic agents with synergistic properties obtained from two entities, which separately are not ready for in vivo applications, and strengthen the possibility of using biomolecules as both a coating for OA-IONP micellar stabilization and as drugs for therapy.

Identification of Metastatic Lymph Nodes in MR Imaging with Faster Region-Based Convolutional Neural Networks

MRI is the gold standard for confirming a pelvic lymph node metastasis diagnosis. Traditionally, medical radiologists have analyzed MRI image features of regional lymph nodes to make diagnostic decisions based on their subjective experience; this diagnosis lacks objectivity and accuracy. This study trained a faster region-based convolutional neural network (Faster R-CNN) with 28,080 MRI images of lymph node metastasis, allowing the Faster R-CNN to read those images and to make diagnoses. For clinical verification, 414 cases of rectal cancer at various medical centers were collected, and Faster R-CNN-based diagnoses were compared with radiologist diagnoses using receiver operating characteristic curves (ROC). The area under the Faster R-CNN ROC was 0.912, indicating a more effective and objective diagnosis. The Faster R-CNN diagnosis time was 20 s/case, which was much shorter than the average time (600 s/case) of the radiologist diagnoses.Significance: Faster R-CNN enables accurate and efficient diagnosis of lymph node metastases. Cancer Res; 78(17); 5135-43. ©2018 AACR.

Magnetosomes Extracted from Magnetospirillum gryphiswaldense as Theranostic Agents in an Experimental Model of Glioblastoma

Magnetic fluid hyperthermia (MFH) with chemically synthesized nanoparticles is currently used in clinical trials as it destroys tumor cells with an extremely localized deposition of thermal energy. In this paper, we investigated an MFH protocol based on magnetic nanoparticles naturally produced by magnetotactic bacteria: magnetosomes. The efficacy of such protocol is tested in a xenograft model of glioblastoma. Mice receive a single intratumoral injection of magnetosomes, and they are exposed three times in a week to an alternating magnetic field with concurrent temperature measurements. MRI is used to visualize the nanoparticles and to monitor tumor size before and after the treatment. Statistically significant inhibition of the tumor growth is detected in subjects exposed to the alternating magnetic field compared to control groups. Moreover, thanks to magnetosomes high transversal relaxivity, their effective delivery to the tumor tissue is monitored by MRI. It is apparent that the efficacy of this protocol is limited by inhomogeneous delivery of magnetosomes to tumor tissue. These results suggest that naturally synthesized magnetosomes could be effectively considered as theranostic agent candidates for hyperthermia based on iron oxide nanoparticles.

Maghemite Nanoparticles with Enhanced Magnetic Properties: One-Pot Preparation and Ultrastable Dextran Shell

In the field of nanomedicine, superparamagnetic nanoparticles are one of the most studied nanomaterials for theranostics. In this study, a one-pot synthesis of magnetic nanoparticles is presented, with an increased control on particle size from 10 to 40 nm. Monitoring of vacuum level is introduced here as a crucial parameter for achieving a fine particle morphology. The magnetic properties of these nanoparticles are highly affected by disorders or mismatches in crystal structure. A prolonged oxidation step is applied to the obtained nanoparticles to transform the magnetic phases into a pure maghemite one, confirmed by high-resolution X-ray photoelectron spectroscopy analysis, by Mössbauer spectrometry and, indirectly, by increased performances in magnetization curves and in relaxation times. Afterward, the attained nanoparticles are transferred into water by a nonderivatized dextran coating. Thermogravimetric analysis confirms that polysaccharide molecules replace oleic acid on the surface by stabilizing the particles in the aqueous phase and culture media. Preliminary in vitro test reveals that the dextran-coated nanoparticles are not passively internalized from the cells. As a proof of concept, a secondary layer of chitosan assures a positive charge to the nanoparticle surface, thus enhancing cellular internalization.

Intranasal instillation of iron oxide nanoparticles induces inflammation and perturbation of trace elements and neurotransmitters, but not behavioral impairment in rats

Over the last decades, engineered nanomaterials have been widely used in various applications due to their interesting properties. Among them, iron oxide nanoparticles (IONPs) are used as theranostic agents for cancer, and also as contrast agents in magnetic resonance imaging. With the increasing production and use of these IONPs, there is an evident raise of IONP exposure and subsequently a higher risk of adverse outcome for humans and the environment. In this work, we aimed to investigate the effects of sub-acute IONP exposure on Wistar rat, particularly (i) on the emotional and learning/memory behavior, (ii) on the hematological and biochemical parameters, (iii) on the neurotransmitter content, and (vi) on the trace element homeostasis. Rats were treated during seven consecutive days by intranasal instillations at a dose of 10 mg/kg body weight. The mean body weight increased significantly in IONP-exposed rats. Moreover, several hematological parameters were normal in treated rats except the platelet count which was increased. The biochemical study revealed that phosphatase alkaline level decreased in IONP-exposed rats, but no changes were observed for the other hepatic enzymes (ALT and AST) levels. The trace element homeostasis was slightly modulated by IONP exposure. Sub-acute intranasal exposure to IONPs increased dopamine and norepinephrine levels in rat brain; however, it did not affect the emotional behavior, the anxiety index, and the learning/memory capacities of rats.

Fe Doped Magnetic Nanodiamonds Made by Ion Implantation as Contrast Agent for MRI

We report in this paper a new MRI contrast agent based on magnetic nanodiamonds fabricated by Fe ion implantation. The Fe atoms that are implanted into the nanodiamonds are not in direct contact with the outside world, enabling this new contrast agent to be free from cell toxicity. The image enhancement was shown clearly through T2 weighted images. The concentration dependence of the T2 relaxation time gives a relaxivity value that is about seven times that of the regular non-magnetic nanodiamonds. Cell viability study has also been performed. It was shown that they were nearly free from cytotoxicity independent of the particle concentration used. The imaging capability demonstrated here adds a new dimension to the medical application of nanodiamonds. In the future one will be able to combine this capability of magnetic nanodiamonds with other functions through surface modifications to perform drug delivery, targeted therapy, localized thermal treatment and diagnostic imaging at the same time.

Recent advances in nanoparticle carriers for photodynamic therapy

This review summarizes recent advances in the development of nanoparticles (NPs) for efficient photodynamic therapy (PDT), particularly the development and application of various NPs based on organic and inorganic materials. PubMed database was used for literature search with the terms including NP, nanomedicine, PDT, photosensitizer (PSs), and drug delivery. For successful PDT, it is essential to deliver PSs to target disease sites. A number of NPs have been developed and tested as the carriers for both imaging and therapy, an approach termed "nanomedicine". Many studies of NP carriers showed increased water solubility and stability of PSs for in vivo injection, and these NP carriers provided benefits including longer circulation in blood and higher accumulation of PSs at disease sites. This review describes new techniques in PDT such as aggregation-induced emission (AIE) and luminescence-based PDT, and provides insights on NPs and PDT for biomedical researchers working to develop or apply NPs in efficient PDT.

Anti-inflammatory Nanomedicine for Cardiovascular Disease

Coronary artery disease, in the development of which inflammation mediated by innate immune cells plays a critical role, is one of the leading causes of death worldwide. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are a widely used lipid-lowering drug that has lipid-independent vasculoprotective effects, such as improvement of endothelial dysfunction, antioxidant properties, and inhibitory effects on inflammation. Despite recent advances in lipid-lowering therapy, clinical trials of statins suggest that anti-inflammatory therapy beyond lipid-lowering therapy is indispensible to further reduce cardiovascular events. One possible therapeutic option to the residual risk is to directly intervene in the inflammatory process by utilizing a nanotechnology-based drug delivery system (nano-DDS). Various nano-sized materials are currently developed as DDS, including micelles, liposomes, polymeric nanoparticles, dendrimers, carbon nanotubes, and metallic nanoparticles. The application of nano-DDS to coronary artery disease is a feasible strategy since the inflammatory milieu enhances incorporation of nano-sized materials into mononuclear phagocytic system and permeability of target lesions, which confers nano-DDS on “passive-targeting” property. Recently, we have developed a polymeric nanoparticle-incorporating statin to maximize its anti-inflammatory property. This statin nanoparticle has been tested in various disease models, including plaque destabilization and rupture, myocardial ischemia-reperfusion injury, and ventricular remodeling after acute myocardial infarction, and its clinical application is in progress. In this review, we present current development of DDS and future perspective on the application of anti-inflammatory nanomedicine to treat life-threatening cardiovascular diseases.

ATP and NADPH coated iron oxide nanoparticles for targeting of highly metabolic tumor cells

The metabolic activity of tumor cells is known to be higher as compared to that of normal cells, which has been previously exploited to deliver nanomedicines to highly metabolic tumor cells. Unfortunately, current strategies, which are mostly based on complex energy sources, such as sugars, showed insufficient accumulation at the target sites. We here report the coating of IONPs with two essential units of cellular metabolism: adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). ATP and NADPH were directly bound to the IONPs' surface using a simple aqueous method. Both molecules were used as coatings, i.e. as stabilizing agents, but also simultaneously as targeting molecules to deliver IONPs to highly metabolic tumor cells. Indeed, we found that the uptake of ATP-IONPs and NADPH-IONPs is correlated with the metabolic activity of tumor cells, especially regarding their cellular ATP levels and NADPH consumption. We also measured one of the highest MRI r₂ relaxivities for both ATP-IONPs and NADPH-IONPs. With the direct coating of IONPs with ATP and NADPH, we therefore provide an optimal platform to stabilize IONPs and at the same time promising properties for the targeting and detection of highly metabolic tumor cells.

Potential Therapeutic Mechanisms and Tracking of Transplanted Stem Cells: Implications for Stroke Treatment

Stem cell therapy is a promising potential therapeutic strategy to treat cerebral ischemia in preclinical and clinical trials. Currently proposed treatments for stroke employing stem cells include the replacement of lost neurons and integration into the existing host circuitry, the release of growth factors to support and promote endogenous repair processes, and the secretion of extracellular vesicles containing proteins, noncoding RNA, or DNA to regulate gene expression in recipient cells and achieve immunomodulation. Progress has been made to elucidate the precise mechanisms underlying stem cell therapy and the homing, migration, distribution, and differentiation of transplanted stem cells in vivo using various imaging modalities. Noninvasive and safe tracer agents with high sensitivity and image resolution must be combined with long-term monitoring using imaging technology to determine the optimal therapy for stroke in terms of administration route, dosage, and timing. This review discusses potential therapeutic mechanisms of stem cell transplantation for the treatment of stroke and the limitations of current therapies. Methods to label transplanted cells and existing imaging systems for stem cell labeling and in vivo tracking will also be discussed.

Erratum to a comprehensive literatures update of clinical researches of superparamagnetic resonance iron oxide nanoparticles for magnetic resonance imaging

[This corrects the article DOI: 10.21037/qims.2017.02.09.].