Resting-state functional magnetic resonance imaging reveals functional connectivity alteration in the experimental autoimmune encephalomyelitis model of multiple sclerosis.

Multiple sclerosis (MS) is an autoimmune degenerative disease targeting white matter in the central nervous system. The most common animal model that mimics MS is experimental autoimmune encephalomyelitis (EAE) and it plays a crucial role in pharmacological research, from the identification of a therapeutic target to the in vivo validation of efficacy. Magnetic resonance imaging (MRI) is largely used to detect MS lesions, and resting-state functional MRI (rsfMRI) to investigate alterations in the brain functional connectivity (FC). MRI was mainly used in EAE studies to detect lesions in the spinal cord and brain. The current longitudinal MRI study aims to validate rsfMRI as a biomarker of the disease progression in the myelin oligodendrocyte glycoprotein 35-55 induced EAE animal model of MS. MR images were acquired 14, 25, and 50 days postimmunization. Seed-based analysis was used to investigate the whole-brain FC with some predefined areas, such as the thalamic regions, cerebellum, motor and somatosensory cortex. When compared with the control group, the EAE group exhibited a slightly altered FC and a decreasing trend in the total number of activated voxels along the disease progression. The most interesting result regards the whole-brain FC with the cerebellum. A hyperconnectivity behavior was found at an early phase and a significant reduced connectivity at a late phase. Moreover, we found a negative correlation between the total number of activated voxels during the late phase and the cumulative disease index. The results obtained provide a clinically relevant experimental platform that may be pivotal for the elucidation of the key mechanisms of accumulation of irreversible disability, as well as the development of innovative therapies for MS. Moreover, the negative correlation between the disease severity and the size of the activated area suggests a possible research pathway to follow for the resolution of the clinico-radiological paradox.

Injectable Thermogelling Nanostructured Ink as Simultaneous Optical and Magnetic Resonance Imaging Contrast Agent for Image-Guided Surgery.

The development of efficient and biocompatible contrast agents is particularly urgent for modern clinical surgery. Nanostructured materials raised great interest as contrast agents for different imaging techniques, for which essential features are high contrasts, and in the case of precise clinical surgery, minimization of the signal spatial dispersion when embedded in biological tissues. This study deals with the development of a multimodal contrast agent based on an injectable hydrogel nanocomposite containing a lanthanide-activated layered double hydroxide coupled to a biocompatible dye (indocyanine green), emitting in the first biological window. This novel nanostructured thermogelling hydrogel behaves as an efficient tissue marker for optical and magnetic resonance imaging because the particular formulation strongly limits its spatial diffusion in biological tissue by exploiting a simple injection. The synergistic combination of these properties permits to employ the hydrogel ink simultaneously for both optical and magnetic resonance imaging, easy monitoring of the biological target, and, at the same time, increasing the spatial resolution during a clinical surgery. The biocompatibility and excellent performance as contrast agents are very promising for possible use in image-guided surgery, which is currently one of the most challenging topics in clinical research.

Structural evolution under physical and chemical stimuli of metastable Au-Fe nanoalloys obtained by laser ablation in liquid.

Metastable alloy nanoparticles are investigated for their variety of appealing properties exploitable for photonics, magnetism, catalysis and nanobiotechnology. Notably, nanophases out of thermodynamic equilibrium feature a complex "ultrastructure" leading to a dynamic evolution of composition and atomic arrangement in response to physical-chemical stimuli. In this manuscript, metastable Au-Fe alloy nanoparticles were produced by laser ablation in liquid, an emerging versatile synthetic approach for freezing multielement nanosystems in non-equilibrium conditions. The Au-Fe nanoalloys were characterized through electron microscopy, elemental analysis, X-ray diffraction and Mössbauer spectroscopy. The dynamics of the structure of the Au-Fe system was tracked at high temperature under vacuum and atmospheric conditions, evidencing the intrinsic transformative nature of the metastable nanoalloy produced by laser ablation in liquid. This dynamic structure is relevant to possible application in several fields, from photocatalysis to nanomedicine, as demonstrated through an experiment of magnetic resonance imaging in biological fluids.

ASC-Exosomes Ameliorate the Disease Progression in SOD1(G93A) Murine Model Underlining Their Potential Therapeutic Use in Human ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive degeneration of motoneurons. To date, there is no effective treatment available. Exosomes are extracellular vesicles that play important roles in intercellular communication, recapitulating the effect of origin cells. In this study, we tested the potential neuroprotective effect of exosomes isolated from adipose-derived stem cells (ASC-exosomes) on the in vivo model most widely used to study ALS, the human SOD1 gene with a G93A mutation (SOD1(G93A)) mouse. Moreover, we compared the effect of two different routes of exosomes administration, intravenous and intranasal. The effect of exosomes administration on disease progression was monitored by motor tests and analysis of lumbar motoneurons and glial cells, neuromuscular junction, and muscle. Our results demonstrated that repeated administration of ASC-exosomes improved the motor performance; protected lumbar motoneurons, the neuromuscular junction, and muscle; and decreased the glial cells activation in treated SOD1(G93A) mice. Moreover, exosomes have the ability to home to lesioned ALS regions of the animal brain. These data contribute by providing additional knowledge for the promising use of ASC-exosomes as a therapy in human ALS.

Multifunctional Nanovectors Based on Polyamidoamine Polymers for Theranostic Application.

We present multifunctional, biocompatible and biodegradable magnetic nanovectors based on different polyamidoamine (PAA) polymers tailored with different diagnostic and therapeutic properties. Using maghemite nanoparticles with average size 15.5 ± 2.8 nm prepared by thermal decomposition, superparamagnetic nanovectors were obtained by coating the nanoparticles with synthetic polymers of PAA. These have a segmented copolymer structure, and bear PAA segments containing different amount of carboxyl groups per repeating units together with PEG segments. These copolymers are thought to combine the binding properties of the carboxylated PAA segments to inorganic nanoparticles, with the stealth properties of the PEG ones. The magnetic, hyperthermal and relaxometric properties of the synthesized samples were investigated. Magnetic measurements revealed that the samples are superparamagnetic at room temperature and the overall magnetic behavior is not affected by the functionalization process. Calorimetric measurements demonstrated a good heating efficiency at alternating magnetic field parameters below the human tolerability threshold (SAR of ca. 70 W/g at 260 Hz and 10.8 kA/m). 1H-NMR relaxivities were relevant compared to the values of the commercial contrast agents over the whole investigated frequency range.

MRI reveals therapeutical efficacy of stem cells: An experimental study on the SOD1(G93A) animal model.

PURPOSE: The first part of the experiment identifies and validates MRI biomarkers distinctive of the disease progression in the transgenic superoxide dismutase gene (SOD1(G93A)) animal model. The second part assesses the efficacy of a mesenchymal stem cell-based therapy through the MRI biomarkers previously defined. METHODS: The first part identifies MRI differences between SOD1(G93A) and healthy mice. The second part of the experiment follows the disease evolution of stem cell-treated and non-stem-cell treated SOD1(G93A) mice. The analysis focused on voxel-based morphometry and T2 mapping on the brain tissues, and T2-weighted imaging and diffusion tensor imaging (DTI) on the hind limbs. RESULTS: Comparing diseased mice to healthy control revealed gray matter alterations in the brainstem area, accompanied by increased T2 relaxation time. Differences in muscle volume, muscle signal intensity, fractional anisotropy, axial diffusivity, and radial diffusivity were measured in the hind limbs. In the comparison between stem cell-treated mice and nontreated ones, differences in muscle volume, muscle signal intensity, and DTI-derived maps were found. CONCLUSION: MRI-derived biomarkers can be used to identify differences between stem cell-treated and nontreated SOD1(G93A) mice. Magn Reson Med 79:459-469, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Ozone Treatment of Grapes During Withering for Amarone Wine: A Multimodal Imaging and Spectroscopic Analysis.

The production of Amarone wine is governed by a disciplinary guideline to preserve its typical features; however, postharvest infections by the fungus Botrytis cinerea (B. cinerea) not only represent a phytosanitary problem but also cause a significant loss of product. In this study, we tested a treatment with mild ozoniztion on grapes for Amarone wine production during withering in the fruttaio (the environment imposed by the disciplinary guideline) and evaluated the impact on berry features by a multimodal imaging approach. The results indicate that short and repeated treatments with low O3 concentrations speed up the naturally occurring berry withering, probably inducing a reorganization of the epicuticular wax layer, and inhibit the development of B. cinerea, blocking the fungus in an intermediate vegetative stage. This pilot study will pave the way to long-term research on Amarone wine obtained from O3-treated grapes.

Quantum dots labelling allows detection of the homing of mesenchymal stem cells administered as immunomodulatory therapy in an experimental model of pancreatic islets transplantation.

Cell transplantation is considered a promising therapeutic approach in several pathologies but still needs innovative and non-invasive imaging technologies to be validated. The use of mesenchymal stem cells (MSCs) attracts major interest in clinical transplantation thanks to their regenerative properties, low immunogenicity and ability to regulate immune responses. In several animal models, MSCs are used in co-transplantation with pancreatic islets (PIs) for the treatment of type I diabetes, supporting graft survival and prolonging normal glycaemia levels. In this study we investigated the homing of systemically administered MSCs in a rat model of pancreatic portal vein transplantation. MSCs labelled with quantum dots (Qdots) were systemically injected by tail vein and monitored by optical fluorescence imaging. The fluorescence signal of the liver in animals co-transplanted with MSCs and PIs was significantly higher than in control animals in which MSCs alone were transplanted. By using magnetic labelling of PIs, the homing of PIs into liver was independently confirmed. These results demonstrate that MSCs injected in peripheral blood vessels preferentially accumulate into liver when PIs are transplanted in the same organ. Moreover, we prove that bimodal MRI-fluorescence imaging allows specific monitoring of the fate of two types of cells.

Functional Magnetic Resonance Imaging of Rats with Experimental Autoimmune Encephalomyelitis Reveals Brain Cortex Remodeling.

Cortical reorganization occurring in multiple sclerosis (MS) patients is thought to play a key role in limiting the effect of structural tissue damage. Conversely, its exhaustion may contribute to the irreversible disability that accumulates with disease progression. Several aspects of MS-related cortical reorganization, including the overall functional effect and likely modulation by therapies, still remain to be elucidated. The aim of this work was to assess the extent of functional cortical reorganization and its brain structural/pathological correlates in Dark Agouti rats with experimental autoimmune encephalomyelitis (EAE), a widely accepted preclinical model of chronic MS. Morphological and functional MRI (fMRI) were performed before disease induction and during the relapsing and chronic phases of EAE. During somatosensory stimulation of the right forepaw, fMRI demonstrated that cortical reorganization occurs in both relapsing and chronic phases of EAE with increased activated volume and decreased laterality index versus baseline values. Voxel-based morphometry demonstrated gray matter (GM) atrophy in the cerebral cortex, and both GM and white matter atrophy were assessed by ex vivo pathology of the sensorimotor cortex and corpus callosum. Neuroinflammation persisted in the relapsing and chronic phases, with dendritic spine density in the layer IV sensory neurons inversely correlating with the number of cluster of differentiation 45-positive inflammatory lesions. Our work provides an innovative experimental platform that may be pivotal for the comprehension of key mechanisms responsible for the accumulation of irreversible brain damage and for the development of innovative therapies to reduce disability in EAE/MS. SIGNIFICANCE STATEMENT: Since the early 2000s, functional MRI (fMRI) has demonstrated profound modifications in the recruitment of cortical areas during motor, cognitive, and sensory tasks in multiple sclerosis (MS) patients. Experimental autoimmune encephalomyelitis (EAE) represents a reliable model of the chronic-progressive variant of MS. fMRI studies in EAE have not been performed extensively up to now. This paper reports fMRI studies in a rat model of MS with somatosensory stimulation of the forepaw. We demonstrated modifications in the recruitment of cortical areas consistent with data from MS patients. To the best of our knowledge, this is the first report of cortical remodeling in a preclinical in vivo model of MS.

Magneto-plasmonic Au-Fe alloy nanoparticles designed for multimodal SERS-MRI-CT imaging.

Diagnostic approaches based on multimodal imaging are needed for accurate selection of the therapeutic regimens in several diseases, although the dose of administered contrast drugs must be reduced to minimize side effects. Therefore, large efforts are deployed in the development of multimodal contrast agents (MCAs) that permit the complementary visualization of the same diseased area with different sensitivity and different spatial resolution by applying multiple diagnostic techniques. Ideally, MCAs should also allow imaging of diseased tissues with high spatial resolution during surgical interventions. Here a new system based on multifunctional Au-Fe alloy nanoparticles designed to satisfy the main requirements of an ideal MCA is reported and their biocompatibility and imaging capability are described. The MCAs show easy and versatile surface conjugation with thiolated molecules, magnetic resonance imaging (MRI) and computed X-ray tomography (CT) signals for anatomical and physiological information (i.e., diagnostic and prognostic imaging), large Raman signals amplified by surface enhanced Raman scattering (SERS) for high sensitivity and high resolution intrasurgical imaging, biocompatibility, exploitability for in vivo use and capability of selective accumulation in tumors by enhanced permeability and retention effect. Taken together, these results show that Au-Fe nanoalloys are excellent candidates as multimodal MRI-CT-SERS imaging agents.

(1) H-MR spectroscopy characterization of the adipose tissue associated with colorectal tumor.

PURPOSE: To investigate colorectal tumor by looking at the lipid tissue around the lesion. Adipose tissue is not only an inert storage system for excess calories, but is involved in several pathological processes linked to tumor development. MATERIALS AND METHODS: We obtained 24 colorectal specimens after surgical excision from patients affected by colorectal cancer at different tumor stages. (1) H-MR spectoscopy (MRS) spectra were collected from two voxels, in proximity of the lesion and far from it, in each specimen with a preclinical scanner. We differentiated patients by pathological tumor stage, and we compared the chemical composition of adipose tissue between patient groups, both close the tumor and far from it. RESULTS: Monounsaturated fatty acids (MUFA) close the lesion are increased at higher tumor stages, while MUFA far from the lesion do not follow this trend. This study is really explorative due to the small numbers of subjects and we are cautious on the interpretation of the results. However, the approach of the present work allows a further insight in the tumor characterization. CONCLUSION: Looking at the lipid tissue around a lesion through (1) H-MRS can return important information regarding its genesis and development.

From Nanothermometry to Bioimaging: Lanthanide-Activated KY3F10 Nanostructures as Biocompatible Multifunctional Tools for Nanomedicine.

Lanthanide-activated fluoride-based nanostructures are extremely interesting multifunctional tools for many modern applications in nanomedicine, e.g., bioimaging, sensing, drug delivery, and photodynamic therapy. Importantly, environmental-friendly preparations using a green chemistry approach, as hydrothermal synthesis route, are nowadays highly desirable to obtain colloidal nanoparticles, directly dispersible in hydrophilic media, as physiological solution. The nanomaterials under investigation are new KY3F10-based citrate-capped core@shell nanostructures activated with several lanthanide ions, namely, Er3+, Yb3+, Nd3+, and Gd3+, prepared as colloidal water dispersions. A new facile microwave-assisted synthesis has been exploited for their preparation, with significant reduction of the reaction times and a fine control of the nanoparticle size. These core@shell multifunctional architectures have been investigated for use as biocompatible and efficient contrast agents for optical, magnetic resonance imaging (MRI) and computerized tomography (CT) techniques. These multifunctional nanostructures are also efficient noninvasive optical nanothermometers. In fact, the lanthanide emission intensities have shown a relevant relative variation as a function of the temperature, in the visible and near-infrared optical ranges, efficiently exploiting ratiometric intensity methods for optical thermometry. Importantly, in contrast with other fluoride hosts, chemical dissolution of KY3F10 citrate-capped nanocrystals in aqueous environment is very limited, of paramount importance for applications in biological fluids. Furthermore, due to the strong paramagnetic properties of lanthanides (e.g., Gd3+), and X-ray absorption of both yttrium and lanthanides, the nanostructures under investigation are extremely useful for MRI and CT imaging. Biocompatibility studies of the nanomaterials have revealed very low cytotoxicity in dfferent human cell lines. All these features point to a successful use of these fluoride-based core@shell nanoarchitectures for simultaneous diagnostics and temperature sensing, ensuring an excellent biocompatibility.

Biocompatible, photo-responsive layer-by-layer polymer nanocapsules with an oil core: in vitro and in vivo study.

In cancer therapy, stimulus-responsive drug delivery systems are of particular interest for reducing side effects in healthy tissues and improving drug selectivity in the tumoral ones. Here, a strategy for the preparation of a photo-responsive cross-linked trilayer deposited onto an oil-in-water nanoemulsion via a layer-by-layer technique is reported. The system is made of completely biocompatible materials such as soybean oil, egg lecithin and glycol chitosan, with heparin as the polymeric shell. The oil core is pre-loaded with curcumin as a model lipophilic active molecule with anti-tumoral properties. The trilayer cross-linkage is performed via a photoinitiator-free thiol-ene 'click' reaction. In particular, the system is implemented with an o-nitrobenzyl group functionalized with a thiol moiety which can perform both the thiol-ene 'click' reaction and the cleavage meant for controlled drug release at two different wavelengths, respectively. So the preparation and characterization of a photo-responsive natural nanocarrier (PNC) that is stable under physiological conditions owing to the thiol-ene cross-linkage are reported. PNC performance has been assessed in vitro on melanoma cells as well as in vivo on xenograft tumour-induced mice.

Doped Ferrite Nanoparticles Exhibiting Self-Regulating Temperature as Magnetic Fluid Hyperthermia Antitumoral Agents, with Diagnostic Capability in Magnetic Resonance Imaging and Magnetic Particle Imaging.

This paper reports a comprehensive investigation of a magnetic nanoparticle (MNP), named M55, which belongs to a class of innovative doped ferrite nanomaterials, characterized by a self-limiting temperature. M55 is obtained from M48, an MNP previously described by our group, by implementing an additional purification step in the synthesis. M55, after citrate and glucose coating, is named G-M55. The present study aimed to demonstrate the properties of G-M55 as a diagnostic contrast agent for MRI and magnetic particle imaging (MPI), and as an antitumoral agent in magnetic fluid hyperthermia (MFH). Similar specific absorption rate values were obtained by standard MFH and by an MPI apparatus. This result is of interest in relation to the application of localized MFH by MPI apparatus. We demonstrated the biocompatibility of G-M55 in a triple-negative human breast cancer line (MDA-MB-231), and its efficacy as an MFH agent in the same cell line. We also demonstrated the efficacy of MFH treatment with G-M55 in an experimental model of breast cancer. Overall, our results pave the way for the clinical application of G-M55 as an MFH agent in breast cancer therapy, allowing not only efficient treatment by both standard MFH apparatus and MPI but also temperature monitoring.

Investigation of adipose tissues in Zucker rats using in vivo and ex vivo magnetic resonance spectroscopy.

In vivo single-voxel magnetic resonance spectroscopy (MRS) at 4.7T and ex vivo high-resolution proton magnetic resonance spectroscopy (HR-NMR) at 500 MHz were used to study the composition of adipose tissues in Zucker obese and Zucker lean rats. Lipid composition was characterized by unsaturation and polyunsaturation indexes and mean chain lengths. In vitro experiments were conducted in known mixtures of triglycerides and oils in order to validate the method. To avoid inaccuracies due to partial peak overlapping in MRS, peak quantification was performed after fitting of spectral peaks by using the QUEST algorithm. The intensity of different spectral lines was also corrected for T2 relaxation. Albeit with different sensitivity and accuracy, both techniques revealed that white adipose tissue is characterized by lower unsaturation and polyunsaturation indexes in obese rats compared with controls. HR-NMR revealed similar differences in brown adipose tissue. The present findings confirm the hypothesis that obese and lean Zucker rats have different adipose tissue composition.

Magnetic nanoparticles--templated assembly of protein subunits: a new platform for carbohydrate-based MRI nanoprobes.

A new approach for the preparation of carbohydrate-coated magnetic nanoparticles is reported. In a first step, we show that the pH-driven assembly-disassembly natural process that occurs in apoferritin protein is effective for the encapsulation of maghemite nanoparticles of different sizes: 4 and 6 nm. In a second step, we demonstrate that the presence of functional amine groups in the outer shell of apoferritin allows functionalization with two carbohydrates, N-acetyl-D-glucosamine and d-mannose. High-resolution electron microscopy (HREM), high angle annular dark field scanning electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS), X-ray diffraction (XRD), and SQUID technique have been used to characterize the magnetic samples, termed herein Apomaghemites. The in vivo magnetic resonance imaging (MRI) studies showed the efficiency in contrasting images for these samples; that is, the r(2) NMR relaxivities are comparable with Endorem (a commercial superparamagnetic MRI contrast agent). The r(2) relaxivity values as well as the pre-contrast and post-contrast T(2)*-weighted images suggested that our systems could be used as perspective superparamagnetic contrast agents for magnetic resonance imaging (MRI). The carbohydrate-functionalized Apomaghemite nanoparticles retained their recognition abilities, as demonstrated by the strong affinity with their corresponding carbohydrate-binding lectins.

Multispectral Cerenkov luminescence tomography for small animal optical imaging.

Quite recently Cerenkov luminescence imaging (CLI) has been introduced as a novel pre-clinical imaging for the in vivo imaging of small animals such as mice. The CLI method is based on the detection of Cerenkov radiation (CR) generated by beta particles as they travel into the animal tissues with an energy such that Cerenkov emission condition is satisfied. This paper describes an image reconstruction method called multi spectral diffuse Cerenkov luminescence tomography (msCLT) in order to obtain 3D images from the detection of CR. The multispectral approach is based on a set of 2D planar images acquired using a number of narrow bandpass filters, and the distinctive information content at each wavelength is used in the 3D image reconstruction process. The proposed msCLT method was tested both in vitro and in vivo using 32P-ATP and all the images were acquired by using the IVIS 200 small animal optical imager (Caliper Life Sciences, Alameda USA). Source depth estimation and spatial resolution measurements were performed using a small capillary source placed between several slices of chicken breast. The theoretical Cerenkov emission spectrum and optical properties of chicken breast were used in the modelling of photon propagation. In vivo imaging was performed by injecting control nude mice with 10 MBq of 32P-ATP and the 3D tracer bio-distribution was reconstructed. Whole body MRI was acquired to provide an anatomical localization of the Cerenkov emission. The spatial resolution obtained from the msCLT reconstructed images of the capillary source showed that the FWHM is about 1.5 mm for a 6 mm depth. Co-registered MRI images showed that the Cerenkov emission regions matches fairly well with anatomical regions, such as the brain, heart and abdomen. Ex vivo imaging of the different organs such as intestine, brain, heart and ribs further confirms these findings. We conclude that in vivo 3D bio-distribution of a pure beta-minus emitting radiopharmaceutical such as 32P-ATP can be obtained using the msCLT reconstruction approach.

Early versus late GD-DTPA MRI enhancement in experimental glioblastomas.

PURPOSE: To compare early versus late enhancement in two glioblastoma models characterized by different infiltrative/edematous patterns. MATERIALS AND METHODS: Three weeks after inoculation into nude mice of U87MG and U251 cells, T1-weighted images were acquired early (10.5 min), intermediate (21 min) and late (30.5 min) after a bolus injection of Gd-DTPA at 300 µ mol/kg dosage. EARLY(TH) and LATE(TH) were the corresponding volumes with an enhancement higher than a threshold TH, defined by the mean (µ) and standard deviation (σ) on a contralateral healthy area. ADD(TH) was the enhancing volume found in LATE(TH) but not in EARLY(TH). T2 imaging of both tumors was performed, and T2 mapping of U251. RESULTS: In all tumors, LATE(TH) was significantly higher than EARLY(TH) for TH ranging from µ+σ to µ+5σ. The ADD(TH) /EARLY(TH) ratio was not significantly different when U251 and U87MG tumors were compared. In the U87MG tumors, some enhancement was observed outside the regularly demarcated T2-hyperintense area. In the U251 tumors, irregularly T2 demarcated, a large portion of ADD(µ+3σ) had normal T2 values. At histology, U251 showed a higher infiltrative pattern than U87MG. CONCLUSION: In these models, the increase over time in the enhancing volume did not depend on the different infiltrative/edematous patterns and was not closely related with edema.

Iron Oxide Nanoparticles as Theranostic Agents in Cancer Immunotherapy.

Starting from the mid-1990s, several iron oxide nanoparticles (NPs) were developed as MRI contrast agents. Since their sizes fall in the tenths of a nanometer range, after i.v. injection these NPs are preferentially captured by the reticuloendothelial system of the liver. They have therefore been proposed as liver-specific contrast agents. Even though their unfavorable cost/benefit ratio has led to their withdrawal from the market, innovative applications have recently prompted a renewal of interest in these NPs. One important and innovative application is as diagnostic agents in cancer immunotherapy, thanks to their ability to track tumor-associated macrophages (TAMs) in vivo. It is worth noting that iron oxide NPs may also have a therapeutic role, given their ability to alter macrophage polarization. This review is devoted to the most recent advances in applications of iron oxide NPs in tumor diagnosis and therapy. The intrinsic therapeutic effect of these NPs on tumor growth, their capability to alter macrophage polarization and their diagnostic potential are examined. Innovative strategies for NP-based drug delivery in tumors (e.g., magnetic resonance targeting) will also be described. Finally, the review looks at their role as tracers for innovative, and very promising, imaging techniques (magnetic particle imaging-MPI).