Non-invasive detection of apoptosis using magnetic resonance imaging and a targeted contrast agent

Non-Invasive Detection, Precise Localization, and Perioperative Navigation of In Vivo Deep Lesions Using Transmission Raman Spectroscopy

Non-invasive detection and precise localization of deep lesions have attracted significant attention for both fundamental and clinical studies. Optical modality techniques are promising with high sensitivity and molecular specificity, but are limited by shallow tissue penetration and the failure to accurately determine lesion depth. Here the authors report in vivo ratiometric surface-enhanced transmission Raman spectroscopy (SETRS) for non-invasive localization and perioperative surgery navigation of deep sentinel lymph nodes in live rats. The SETRS system uses ultrabright surface-enhanced Raman spectroscopy (SERS) nanoparticles with a low detection limit of 10 pM and a home-built photosafe transmission Raman spectroscopy setup. The ratiometric SETRS strategy is proposed based on the ratio of multiple Raman spectral peaks for obtaining lesion depth. Via this strategy, the depth of the phantom lesions in ex vivo rat tissues is precisely determined with a mean-absolute-percentage-error of 11.8%, and the accurate localization of a 6-mm-deep rat popliteal lymph node is achieved. The feasibility of ratiometric SETRS allows the successful perioperative navigation of in vivo lymph node biopsy surgery in live rats under clinically safe laser irradiance. This study represents a significant step toward the clinical translation of TRS techniques, providing new insights for the design and implementation of in vivo SERS applications.

Preclinical PET Imaging of Tumor Cell Death following Therapy Using Gallium-68-Labeled C2Am

There is an unmet clinical need for imaging agents capable of detecting early evidence of tumor cell death, since the timing, extent, and distribution of cell death in tumors following treatment can give an indication of treatment outcome. We describe here 68Ga-labeled C2Am, which is a phosphatidylserine-binding protein, for imaging tumor cell death in vivo using positron emission tomography (PET). A one-pot synthesis of 68Ga-C2Am (20 min, 25 °C, >95% radiochemical purity) has been developed, using a NODAGA-maleimide chelator. The binding of 68Ga-C2Am to apoptotic and necrotic tumor cells was assessed in vitro using human breast and colorectal cancer cell lines, and in vivo, using dynamic PET measurements in mice implanted subcutaneously with the colorectal tumor cells and treated with a TRAIL-R2 agonist. 68Ga-C2Am showed predominantly renal clearance and low retention in the liver, spleen, small intestine, and bone and generated a tumor-to-muscle (T/m) ratio of 2.3 ± 0.4, at 2 h post probe administration and at 24 h following treatment. 68Ga-C2Am has the potential to be used in the clinic as a PET tracer for assessing early treatment response in tumors.

Methodological advances in necroptosis research: from challenges to solutions

Necroptosis is currently attracting the attention of the scientific community for its broad implications in inflammatory diseases and cancer. However, detecting ongoing necroptosis in vivo under both experimental and clinical disease conditions remains challenging. The technical barrier lies in four aspects, namely tissue sampling, real-time in vivo monitoring, specific markers, and distinction between different types of cell death. In this review, we presented the latest methodological advances for in vivo necroptosis identification. The advances highlighted the multi-parameter flow cytometry, sA5-YFP tool, radiolabeled Annexin V/Duramycin, Gallium-68-labeled IRDye800CW contrast agent, and SMART platform in vivo. We also discussed the up-to-date research models in studying necroptosis, particularly the mice models for manipulating and monitoring necroptosis. Based on these recent advances, this review aims to provide some advice on current necroptosis techniques and approaches.

Decorated bacteria and the application in drug delivery

The use of living bacteria either as therapeutic agents or drug carriers has shown great potential in treating a multitude of intractable diseases. However, cells are often fragile to unfriendly environmental stressors and limited by inadequately therapeutic responses, leading to unwanted cell death and a decline in treatment efficacy. Surface decoration of bacteria has emerged as a simple yet useful strategy that not only confers bacteria with extra capacity to resist environmental threats but also endows them with exogenous characteristics that are neither inherent nor naturally achievable. In this review, we systematically introduce the advancements of physicochemical and biological technologies for surface modification of bacteria, especially the single-cell surface decoration strategies of individual bacteria. We highlight the recent progress on surface decoration that aims to improve the bioavailability and efficacy of therapeutic bacterial agents and also to achieve enhanced and targeted delivery of conventional drugs. The promises along with challenges of surface-decorated bacteria as drug delivery systems for applications in cancer therapy, intestinal disease treatment, bioimaging, and diagnosis are further discussed with respect to future clinical translation. This review offers an overview of the advances of decorated bacteria for drug delivery applications and would contribute to the development of the next generation of advanced bacterial-based therapies.

A Hybrid Imaging Platform(CT/PET/FMI) for Evaluating Tumor Necrosis and Apoptosis in Real-Time

Multimodality imaging is an advanced imaging tool for monitoring tumor behavior and therapy in vivo. In this study, we have developed a novel hybrid tri-modality system that includes two molecular imaging methods: positron emission computed tomography (PET) and fluorescence molecular imaging (FMI) and the anatomic imaging modality X-ray computed tomography (CT). The following paper describes the system development. Also, its imaging performance was tested in vitro (phantom) and in vivo, in Balb/c nude mice bearing a head and neck tumor xenograft treated with novel gene therapy [a new approach to the delivery of recombinant bacterial gene (IL-24-expressing strain)]. Using the tri-modality imaging system, we simultaneously monitored the therapeutic effect, including the apoptotic and necrotic induction within the tumor in vivo. The apoptotic induction was examined in real-time using an 18F-ML-10 tracer; the cell death was detected using ICG. A CT was used to evaluate the anatomical situation. An increased tumor inhibition (including tumor growth and tumor cell apoptosis) was observed in the treatment group compared to the control groups, which further confirmed the therapeutic effect of a new IL-24-expressing strain gene therapy on the tumor in vivo. By being able to offer concurrent morphological and functional information, our system is able to characterize malignant tissues more accurately. Therefore, this new tri-modality system (PET/CT/FMI) is an effective imaging tool for simultaneously investigating and monitoring tumor progression and therapy outcomes in vivo.

Quantitative imaging of apoptosis following oncolytic virotherapy by magnetic resonance fingerprinting aided by deep learning

Non-invasive imaging methods for detecting intratumoural viral spread and host responses to oncolytic virotherapy are either slow, lack specificity or require the use of radioactive or metal-based contrast agents. Here we show that in mice with glioblastoma multiforme, the early apoptotic responses to oncolytic virotherapy (characterized by decreased cytosolic pH and reduced protein synthesis) can be rapidly detected via chemical-exchange-saturation-transfer magnetic resonance fingerprinting (CEST-MRF) aided by deep learning. By leveraging a deep neural network trained with simulated magnetic resonance fingerprints, CEST-MRF can generate quantitative maps of intratumoural pH and of protein and lipid concentrations by selectively labelling the exchangeable amide protons of endogenous proteins and the exchangeable macromolecule protons of lipids, without requiring exogenous contrast agents. We also show that in a healthy volunteer, CEST-MRF yielded molecular parameters that are in good agreement with values from the literature. Deep-learning-aided CEST-MRF may also be amenable to the characterization of host responses to other cancer therapies and to the detection of cardiac and neurological pathologies.

Large field-of-view non-invasive imaging through scattering layers using fluctuating random illumination

Non-invasive optical imaging techniques are essential diagnostic tools in many fields. Although various recent methods have been proposed to utilize and control light in multiple scattering media, non-invasive optical imaging through and inside scattering layers across a large field of view remains elusive due to the physical limits set by the optical memory effect, especially without wavefront shaping techniques. Here, we demonstrate an approach that enables non-invasive fluorescence imaging behind scattering layers with field-of-views extending well beyond the optical memory effect. The method consists in demixing the speckle patterns emitted by a fluorescent object under variable unknown random illumination, using matrix factorization and a novel fingerprint-based reconstruction. Experimental validation shows the efficiency and robustness of the method with various fluorescent samples, covering a field of view up to three times the optical memory effect range. Our non-invasive imaging technique is simple, neither requires a spatial light modulator nor a guide star, and can be generalized to a wide range of incoherent contrast mechanisms and illumination schemes.

One-pot synthesis of carboxymethyl-dextran coated iron oxide nanoparticles (CION) for preclinical fMRI and MRA applications

Superparamagnetic iron-oxide nanoparticles are robust contrast agents for magnetic resonance imaging (MRI) used for sensitive structural and functional mapping of the cerebral blood volume (CBV) when administered intravenously. To date, many CBV-MRI studies are conducted with Feraheme, manufactured for the clinical treatment of iron-deficiency. Unfortunately, Feraheme is currently not available outside the United States due to commercial and regulatory constraints, making CBV-MRI methods either inaccessible or very costly to achieve. To address this barrier, we developed a simple, one-pot recipe to synthesize Carboxymethyl-dextran coated Iron Oxide Nanoparticles, namely, “CION”, suitable for preclinical CBV-MRI applications. Here we disseminate a step-by-step instruction of our one-pot synthesis protocol, which allows CION to be produced in laboratories with minimal cost. We also characterized different CION-conjugations by manipulating polymer to metal stoichiometric ratio in terms of their size, surface chemistry, and chemical composition, and shifts in MR relaxivity and pharmacokinetics. We performed several proof-of-concept experiments in vivo, demonstrating the utility of CION for functional and structural MRI applications, including hypercapnic CO₂ challenge, visual stimulation, targeted optogenetic stimulation, and microangiography. We also present evidence that CION can serve as a cross-modality research platform by showing concurrent in vivo optical and MRI measurement of CBV using fluorescent-labeled CION. The simplicity and cost-effectiveness of our one-pot synthesis method should allow researchers to reproduce CION and tailor the relaxivity and pharmacokinetics according to their imaging needs. It is our hope that this work makes CBV-MRI more openly available and affordable for a variety of research applications.

Solvothermal Synthesis Combined with Design of Experiments-Optimization Approach for Magnetite Nanocrystal Clusters

Magnetite nanocrystal clusters are being investigated for their potential applications in catalysis, magnetic separation, and drug delivery. Controlling their size and size distribution is of paramount importance and often requires tedious trial-and-error experimentation to determine the optimal conditions necessary to synthesize clusters with the desired properties. In this work, magnetite nanocrystal clusters were prepared via a one-pot solvothermal reaction, starting from an available protocol. In order to optimize the experimental factors controlling their synthesis, response surface methodology (RSM) was used. The size of nanocrystal clusters can be varied by changing the amount of stabilizer (tribasic sodium citrate) and the solvent ratio (diethylene glycol/ethylene glycol). Tuning the experimental conditions during the optimization process is often limited to changing one factor at a time, while the experimental design allows for variation of the factors’ levels simultaneously. The efficiency of the design to achieve maximum refinement for the independent variables (stabilizer amount, diethylene glycol/ethylene glycol (DEG/EG) ratio) towards the best conditions for spherical magnetite nanocrystal clusters with desirable size (measured by scanning electron microscopy and dynamic light scattering) and narrow size distribution as responses were proven and tested. The optimization procedure based on the RSM was then used in reverse mode to determine the factors from the knowledge of the response to predict the optimal synthesis conditions required to obtain a good size and size distribution. The RSM model was validated using a plethora of statistical methods. The design can facilitate the optimization procedure by overcoming the trial-and-error process with a systematic model-guided approach.

A review of green methods for phyto-fabrication of hematite (α-Fe2O3) nanoparticles and their characterization, properties, and applications

The aim of the current work is the introduction of a quick and simple literature survey about the bio-fabrication of the Alpha Hematite nanoparticles (α-Fe₂O₃) using the plant extracts green method. The survey manifested the utilities of the environmentally friendly biosynthesis methods via extracting different plant species, some of its important physicochemical properties, various instrumental analysis characterization tools, and potential applications.

18F-C2Am: a targeted imaging agent for detecting tumor cell death in vivo using positron emission tomography

INTRODUCTION

Trialing novel cancer therapies in the clinic would benefit from imaging agents that can detect early evidence of treatment response. The timing, extent and distribution of cell death in tumors following treatment can give an indication of outcome. We describe here an 18F-labeled derivative of a phosphatidylserine-binding protein, the C2A domain of Synaptotagmin-I (C2Am), for imaging tumor cell death in vivo using PET.

METHODS

A one-pot, two-step automated synthesis of N-(5-[18F]fluoropentyl)maleimide (60 min synthesis time, > 98% radiochemical purity) has been developed, which was used to label the single cysteine residue in C2Am within 30 min at room temperature. Binding of 18F-C2Am to apoptotic and necrotic tumor cells was assessed in vitro, and also in vivo, by dynamic PET and biodistribution measurements in mice bearing human tumor xenografts treated with a TRAILR2 agonist or with conventional chemotherapy. C2Am detection of tumor cell death was validated by correlation of probe binding with histological markers of cell death in tumor sections obtained immediately after imaging.

RESULTS

18F-C2Am showed a favorable biodistribution profile, with predominantly renal clearance and minimal retention in spleen, liver, small intestine, bone and kidney, at 2 h following probe administration. 18F-C2Am generated tumor-to-muscle (T/m) ratios of 6.1 ± 2.1 and 10.7 ± 2.4 within 2 h of probe administration in colorectal and breast tumor models, respectively, following treatment with the TRAILR2 agonist. The levels of cell death (CC3 positivity) following treatment were 12.9-58.8% and 11.3-79.7% in the breast and colorectal xenografts, respectively. Overall, a 20% increase in CC3 positivity generated a one unit increase in the post/pre-treatment tumor contrast. Significant correlations were found between tracer uptake post-treatment, at 2 h post-probe administration, and histological markers of cell death (CC3: Pearson R = 0.733, P = 0.0005; TUNEL: Pearson R = 0.532, P = 0.023).

CONCLUSION

The rapid clearance of 18F-C2Am from the blood pool and low kidney retention allowed the spatial distribution of cell death in a tumor to be imaged during the course of therapy, providing a rapid assessment of tumor treatment response. 18F-C2Am has the potential to be used in the clinic to assess early treatment response in tumors.

Improved non-invasive positron emission tomographic imaging of chemotherapy-induced tumor cell death using Zirconium-89-labeled APOMAB®

Purpose

The chimeric monoclonal antibody (mAb) chDAB4 (APOMAB®) targets the Lupus associated (La)/Sjögren Syndrome-B (SSB) antigen, which is over-expressed in tumors but only becomes available for antibody binding in dead tumor cells. Hence, chDAB4 may be used as a novel theranostic tool to distinguish between responders and nonresponders early after chemotherapy. Here, we aimed to ascertain which positron emitter, Zirconium-89 ([⁸⁹Zr]Zr^IV) or Iodine-124 ([¹²⁴I]I), was best suited to label chDAB4 for post-chemotherapy PET imaging of tumor-bearing mice and to determine which of two different bifunctional chelators provided optimal tumor imaging by PET using [⁸⁹Zr]Zr^IV-labeled chDAB4.

Methods

C57BL/6 J mice bearing subcutaneous syngeneic tumors of EL4 lymphoma were either untreated or given chemotherapy, then administered radiolabeled chDAB4 after 24 h with its biodistribution examined using PET and organ assay. We compared chDAB4 radiolabeled with [⁸⁹Zr] Zr^IV or [¹²⁴I] I, or [⁸⁹Zr]Zr-chDAB4 using either DFO-NCS or DFOSq as a chelator.

Results

After chemotherapy, [⁸⁹Zr]Zr-chDAB4 showed higher and prolonged mean (± SD) tumor uptake of 29.5 ± 5.9 compared to 7.8 ± 1.2 for [¹²⁴I] I -chDAB4. In contrast, antibody uptake in healthy tissues was not affected. Compared to DFO-NCS, DFOSq did not result in significant differences in tumor uptake of [⁸⁹Zr]Zr-chDAB4 but did alter the tumor:liver ratio in treated mice 3 days after injection in favour of DFOSq (8.0 ± 1.1) compared to DFO-NCS (4.2 ± 0.7).

Conclusion

ImmunoPET using chDAB4 radiolabeled with residualizing [⁸⁹Zr] Zr^IV rather than [¹²⁴I] I optimized post-chemotherapy tumor uptake. Further, PET imaging characteristics were improved by DFOSq rather than DFO-NCS. Therefore, the radionuclide/chelator combination of [⁸⁹Zr] Zr^IV and DFOSq is preferred for the imminent clinical evaluation of chDAB4 as a selective tumor cell death radioligand.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s41181-020-00109-6.

The first visualization of chemotherapy-induced tumor apoptosis via magnetic particle imaging in a mouse model

Imaging technologies that allow non-radiative visualization and quantification of apoptosis have a great potential for assessing therapy response, early diagnosis, and disease monitoring. Magnetic particle imaging (MPI), the direct imaging of magnetic nanoparticles as positive contrast agent and sole signal source, enables high image contrast (no tissue background signal), potential high sensitivity, and quantifiable signal intensity. These properties confer a great potential for application to tumor apoptosis monitoring. In this study, a simple and robust method was used to conjugate Alexa Fluor 647-AnnexinV (AF647-Anx), which can avidly bind to apoptotic cells, to superparamagnetic iron oxide (SPIO) nanoparticles, termed AF647-Anx-SPIO, which serves as an MPI-detectable tracer. Based on this apoptosis-specific tracer, MPI can accurately and unambiguously detect and quantify apoptotic tumor cells. AF647-Anx-SPIO showed relatively high affinity for apoptotic cells, and differences in binding between treated (apoptotic rate 67.21% ± 1.36%) and untreated (apoptotic rate 10.12 ± 0.11%) cells could be detected by MPI in vitro (P < 0.05). Moreover, the imaging signal was almost proportional to the number of apoptotic cells determined using an MPI scanner (R ² = 0.99). There was a greater accumulation of AF647-Anx-SPIO in tumors of drug-treated animals than in tumors of untreated animals (P < 0.05), and the difference could be detected by MPI ex vivo, while for in vivo imaging, no MPI imaging signal was detected in either group. Overall, this preliminary study demonstrates that MPI could be a potential imaging modality for tumor apoptosis imaging.

Three Dimensional Reconstruction Models for Medical Modalities: A Comprehensive Investigation and Analysis

BACKGROUND

Image reconstruction is the mathematical process which converts the signals obtained from the scanning machine into an image. The reconstructed image plays a fundamental role in the planning of surgery and research in the medical field.

DISCUSSION

This paper introduces the first comprehensive survey of the literature about medical image reconstruction related to diseases, presenting a categorical study about the techniques and analyzing advantages and disadvantages of each technique. The images obtained by various imaging modalities like MRI, CT, CTA, Stereo radiography and Light field microscopy are included. A comparison on the basis of the reconstruction technique, Imaging Modality and Visualization, Disease, Metrics for 3D reconstruction accuracy, Dataset and Execution time, Evaluation of the technique is also performed.

CONCLUSION

The survey makes an assessment of the suitable reconstruction technique for an organ, draws general conclusions and discusses the future directions.

Imaging Cell Death: Focus on Early Evaluation of Tumor Response to Therapy

Cell death plays a prominent role in the treatment of cancer, because most anticancer therapies act by the induction of cell death including apoptosis, necrosis, and other pathways of cell death. Imaging cell death helps to identify treatment responders from nonresponders and thus enables patient-tailored therapy, which will increase the likelihood of treatment response and ultimately lead to improved patient survival. By taking advantage of molecular probes that specifically target the biomarkers/biochemical processes of cell death, cell death imaging can be successfully achieved. In recent years, with the increased understanding of the molecular mechanism of cell death, a variety of well-defined biomarkers/biochemical processes of cell death have been identified. By targeting these established cell death biomarkers/biochemical processes, a set of molecular imaging probes have been developed and evaluated for early monitoring treatment response in tumors. In this review, we mainly present the recent advances in identifying useful biomarkers/biochemical processes for both apoptosis and necrosis imaging and in developing molecular imaging probes targeting these biomarkers/biochemical processes, with a focus on their application in early evaluation of tumor response to therapy.

Recent Advances of Bioresponsive Nano-Sized Contrast Agents for Ultra-High-Field Magnetic Resonance Imaging

The ultra-high-field magnetic resonance imaging (MRI) nowadays has been receiving enormous attention in both biomaterial research and clinical diagnosis. MRI contrast agents are generally comprising of T1-weighted and T2-weighted contrast agent types, where T1-weighted contrast agents show positive contrast enhancement with brighter images by decreasing the proton's longitudinal relaxation times and T2-weighted contrast agents show negative contrast enhancement with darker images by decreasing the proton's transverse relaxation times. To meet the incredible demand of MRI, ultra-high-field T2 MRI is gradually attracting the attention of research and medical needs owing to its high resolution and high accuracy for detection. It is anticipated that high field MRI contrast agents can achieve high performance in MRI imaging, where parameters of chemical composition, molecular structure and size of varied contrast agents show contrasted influence in each specific diagnostic test. This review firstly presents the recent advances of nanoparticle contrast agents for MRI. Moreover, multimodal molecular imaging with MRI for better monitoring is discussed during biological process. To fasten the process of developing better contrast agents, deep learning of artificial intelligent (AI) can be well-integrated into optimizing the crucial parameters of nanoparticle contrast agents and achieving high resolution MRI prior to the clinical applications. Finally, prospects and challenges are summarized.

Dynamic, Simultaneous Concentration Mapping of Multiple MRI Contrast Agents with Dual Contrast - Magnetic Resonance Fingerprinting

Synchronous assessment of multiple MRI contrast agents in a single scanning session would provide a new "multi-color" imaging capability similar to fluorescence imaging but with high spatiotemporal resolution and unlimited imaging depth. This multi-agent MRI technology would enable a whole new class of basic science and clinical MRI experiments that simultaneously explore multiple physiologic/molecular events in vivo. Unfortunately, conventional MRI acquisition techniques are only capable of detecting and quantifying one paramagnetic MRI contrast agent at a time. Herein, the Dual Contrast - Magnetic Resonance Fingerprinting (DC-MRF) methodology was extended for in vivo application and evaluated by simultaneously and dynamically mapping the intra-tumoral concentration of two MRI contrast agents (Gd-BOPTA and Dy-DOTA-azide) in a mouse glioma model. Co-registered gadolinium and dysprosium concentration maps were generated with sub-millimeter spatial resolution and acquired dynamically with just over 2-minute temporal resolution. Mean tumor Gd and Dy concentration measurements from both single agent and dual agent DC-MRF studies demonstrated significant correlations with ex vivo mass spectrometry elemental analyses. This initial in vivo study demonstrates the potential for DC-MRF to provide a useful dual-agent MRI platform.

Spectroscopic Assessment of Gold Nanoparticle Biodistribution Using Surface Plasmon Resonance Phenomena

Pharmacokinetic (PK) evaluation of nanomaterials are crucial for further clinical development of imaging nanomaterials. In spite of huge advances in nanoparticle-based biomedical research, PK assessment typically requires substantial resources. Here, we show a simple, inexpensive, and yet precise analytical method applicable to the PK interrogation of gold nanoparticles (AuNPs) in the body. We have developed a UV-vis spectroscopic technique that utilizes mechanochemical treatments to separate AuNPs from tissues and then employs surface plasmon of extracted AuNPs to quantify their distribution in the body. This method allows the detection of 10 μg/mL of AuNPs in solution, as was confirmed by using inductively coupled plasma mass spectrometry. We demonstrate biodistribution of fibrin-targeted AuNPs that enable microCT-based visualization of arterial thrombi in mice: blood and thrombi as well as various organs. We believe that our method is generally applicable to most PK studies utilizing AuNPs in medical applications.

Flexible Ferrofluids: Design and Applications

Ferrofluids, also known as ferromagnetic particle suspensions, are materials with an excellent magnetic response, which have attracted increasing interest in both industrial production and scientific research areas. Because of their outstanding features, such as rapid magnetic reaction, flexible flowability, as well as tunable optical and thermal properties, ferrofluids have found applications in various fields, including material science, physics, chemistry, biology, medicine, and engineering. Here, a comprehensive, in-depth insight into the diverse applications of ferrofluids from material fabrication, droplet manipulation, and biomedicine to energy and machinery is provided. Design of ferrofluid-related devices, recent developments, as well as present challenges and future prospects are also outlined.

Imaging of cancer lipid metabolism in response to therapy

Lipids represent a diverse array of molecules essential to the cell's structure, defense, energy, and communication. Lipid metabolism can often become dysregulated during tumor development. During cancer therapy, targeted inhibition of cell proliferation can likewise cause widespread and drastic changes in lipid composition. Molecular imaging techniques have been developed to monitor altered lipid profiles as a biomarker for cancer diagnosis and treatment response. For decades, MRS has been the dominant non-invasive technique for studying lipid metabolite levels. Recent insights into the oncogenic transformations driving changes in lipid metabolism have revealed new mechanisms and signaling molecules that can be exploited using optical imaging, mass spectrometry imaging, and positron emission tomography. These novel imaging modalities have provided researchers with a diverse toolbox to examine changes in lipids in response to a wide array of anticancer strategies including chemotherapy, radiation therapy, signal transduction inhibitors, gene therapy, immunotherapy, or a combination of these strategies. The understanding of lipid metabolism in response to cancer therapy continues to evolve as each therapeutic method emerges, and this review seeks to summarize the current field and areas of unmet needs.

Nanoparticles and cancer therapy: Perspectives for application of nanoparticles in the treatment of cancers

Rapid growth in nanotechnology toward the development of nanomedicine agents holds massive promise to improve therapeutic approaches against cancer. Nanomedicine products represent an opportunity to achieve sophisticated targeting strategies and multifunctionality. Nowadays, nanoparticles (NPs) have multiple applications in different branches of science. In recent years, NPs have repetitively been reported to play a significant role in modern medicine. They have been analyzed for different clinical applications, such as drug carriers, gene delivery to tumors, and contrast agents in imaging. A wide range of nanomaterials based on organic, inorganic, lipid, or glycan compounds, as well as on synthetic polymers has been utilized for the development and improvement of new cancer therapeutics. In this study, we discuss the role of NPs in treating cancer among different drug delivery methods for cancer therapy.

Carbon Dots as a New Class of Diamagnetic Chemical Exchange Saturation Transfer (diaCEST) MRI Contrast Agents

While carbon dots (C-dots) have been extensively investigated pertaining to their fluorescent, phosphorescent, electrochemiluminescent, optoelectronic, and catalytic features, their inherent chemical exchange saturation transfer magnetic resonance imaging (CEST MRI) properties are unknown. By virtue of their hydrophilicity and abundant exchangeable protons of hydroxyl, amine, and amide anchored on the surface, we report here that C-dots can be adapted as effective diamagnetic CEST (diaCEST) MRI contrast agents. As a proof-of-concept demonstration, human glioma cells were labeled with liposomes with or without encapsulated C-dots and implanted in mouse brain. In vivo CEST MRI was able to clearly differentiate labeled cells from non-labeled cells. The present findings may encourage new applications of C-dots for in vivo imaging in deep tissues, which is currently not possible using conventional fluorescent (near-infrared) C-dots.

The Continuing Evolution of Molecular Functional Imaging in Clinical Oncology: The Road to Precision Medicine and Radiogenomics (Part II)

The present era of precision medicine sees "cancer" as a consequence of molecular derangements occurring at the commencement of the disease process, with morphological changes happening much later in the process of tumourigenesis. Conventional imaging techniques, such as computed tomography (CT), ultrasound (US) and magnetic resonance imaging (MRI) play an integral role in the detection of disease at the macroscopic level. However, molecular functional imaging (MFI) techniques entail the visualisation and quantification of biochemical and physiological processes occurring during tumourigenesis. MFI has the potential to play a key role in heralding the transition from the concept of "one-size-fits-all" treatment to "precision medicine". Integration of MFI with other fields of tumour biology such as genomics has spawned a novel concept called "radiogenomics", which could serve as an indispensable tool in translational cancer research. With recent advances in medical image processing, such as texture analysis, deep learning and artificial intelligence, the future seems promising; however, their clinical utility remains unproven at present. Despite the emergence of novel imaging biomarkers, the majority of these require validation before clinical translation is possible. In this two part review, we discuss the systematic collaboration across structural, anatomical and molecular imaging techniques that constitute MFI. Part I reviews positron emission tomography, radiogenomics, AI, and optical imaging, while part II reviews MRI, CT and ultrasound, their current status, and recent advances in the field of precision oncology.

Tracking Stem Cell Implants in Cartilage Defects of Minipigs by Using Ferumoxytol-enhanced MRI

Background Cartilage repair outcomes of matrix-associated stem cell implants (MASIs) in patients have been highly variable. Conventional MRI cannot help distinguish between grafts that will and grafts that will not repair the underlying cartilage defect until many months after the repair. Purpose To determine if ferumoxytol nanoparticle labeling could be used to depict successful or failed MASIs compared with conventional MRI in a large-animal model. Materials and Methods Between January 2016 and December 2017, 10 Göttingen minipigs (n = 5 male; n = 5 female; mean age, 6 months ± 5.1; age range, 4-20 months) received implants of unlabeled (n = 12) or ferumoxytol-labeled (n = 20) viable and apoptotic MASIs in cartilage defects of the distal femur. All MASIs were serially imaged with MRI on a 3.0-T imaging unit at week 1 and weeks 2, 4, 8, 12, and 24, with calculation of T2 relaxation times. Cartilage regeneration outcomes were assessed by using the MR observation of cartilage repair tissue (MOCART) score (scale, 0-100), the Pineda score, and histopathologic quantification of collagen 2 production in the cartilage defect. Findings were compared by using the unpaired Wilcoxon rank sum test, a linear regression model, the Fisher exact test, and Pearson correlation. Results Ferumoxytol-labeled MASIs showed significant T2 shortening (22.2 msec ± 3.2 vs 27.9 msec ± 1.8; P < .001) and no difference in cartilage repair outcomes compared with unlabeled control MASIs (P > .05). At week 2 after implantation, ferumoxytol-labeled apoptotic MASIs showed a loss of iron signal and higher T2 relaxation times compared with ferumoxytol-labeled viable MASIs (26.6 msec ± 4.9 vs 20.8 msec ± 5.3; P = .001). Standard MRI showed incomplete cartilage defect repair of apoptotic MASIs at 24 weeks. Iron signal loss at 2 weeks correlated with incomplete cartilage repair, diagnosed at histopathologic examination at 12-24 weeks. Conclusion Ferumoxytol nanoparticle labeling can accelerate the diagnosis of successful and failed matrix-associated stem cell implants at MRI in a large-animal model. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Sneag and Potter in this issue.

Molecular Imaging of the Heart

Multimodality cardiovascular imaging is routinely used to assess cardiac function, structure, and physiological parameters to facilitate the diagnosis, characterization, and phenotyping of numerous cardiovascular diseases (CVD), as well as allows for risk stratification and guidance in medical therapy decision-making. Although useful, these imaging strategies are unable to assess the underlying cellular and molecular processes that modulate pathophysiological changes. Over the last decade, there have been great advancements in imaging instrumentation and technology that have been paralleled by breakthroughs in probe development and image analysis. These advancements have been merged with discoveries in cellular/molecular cardiovascular biology to burgeon the field of cardiovascular molecular imaging. Cardiovascular molecular imaging aims to noninvasively detect and characterize underlying disease processes to facilitate early diagnosis, improve prognostication, and guide targeted therapy across the continuum of CVD. The most-widely used approaches for preclinical and clinical molecular imaging include radiotracers that allow for high-sensitivity in vivo detection and quantification of molecular processes with single photon emission computed tomography and positron emission tomography. This review will describe multimodality molecular imaging instrumentation along with established and novel molecular imaging targets and probes. We will highlight how molecular imaging has provided valuable insights in determining the underlying fundamental biology of a wide variety of CVDs, including: myocardial infarction, cardiac arrhythmias, and nonischemic and ischemic heart failure with reduced and preserved ejection fraction. In addition, the potential of molecular imaging to assist in the characterization and risk stratification of systemic diseases, such as amyloidosis and sarcoidosis will be discussed. © 2019 American Physiological Society. Compr Physiol 9:477-533, 2019.

Application of Imaging Technologies in Breast Cancer Detection: A Review Article

One of the techniques utilised in the management of cancer in all stages is multiple biomedical imaging. Imaging as an important part of cancer clinical protocols can provide a variety of information about morphology, structure, metabolism and functions. Application of imaging technics together with other investigative apparatus including in fluids analysis and vitro tissue would help clinical decision-making. Mixed imaging techniques can provide supplementary information used to improve staging and therapy planning. Imaging aimed to find minimally invasive therapy to make better results and reduce side effects. Probably, the most important factor in reducing mortality of certain cancers is an early diagnosis of cancer via screening based on imaging. The most common cancer in women is breast cancer. It is considered as the second major cause of cancer deaths in females, and therefore it remained as an important medical and socio-economic issue. Medical imaging has always formed part of breast cancer care and has used in all phases of cancer management from detection and staging to therapy monitoring and post-therapeutic follow-up. An essential action to be performed in the preoperative staging of breast cancer based on breast imaging. The general term of breast imaging refers to breast sonography, mammography, and magnetic resonance tomography (MRT) of the breast (magnetic resonance mammography, MRM).

Further development in technology will lead to increase imaging speed to meet physiological processes requirements. One of the issues in the diagnosis of breast cancer is sensitivity limitation. To overcome this limitation, complementary imaging examinations are utilised that traditionally includes screening ultrasound, and combined mammography and ultrasound. Development in targeted imaging and therapeutic agents calls for close cooperation among academic environment and industries such as biotechnological, IT and pharmaceutical industries.

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.

Radiosynthesis and preliminary in vivo evaluation of 18F-labelled glycosylated duramycin peptides for imaging of phosphatidylethanolamine during apoptosis

[¹⁸F]-Labelled duramycin derivatives incorporating hydrophilic aminogalacturonic acid moieties were prepared as tracers for in vivo imaging of phosphatidylethanolamine during apoptosis.

AuNP-peptide probe for caspase-3 detection in living cells by SERS

Colloidal nanoparticles can be used as surface-enhanced Raman scattering (SERS) substrates because the very close spacing between particles existing in these colloidal systems is beneficial for the generation of extremely strong and highly spatially localized electric field enhancements. Herein, a caspase-3-specified peptide was used as a molecular cross-linker to engineer gold nanoparticle (AuNP) junctions in a controllable manner. The peptide was designed with a sequence of CCALNNPFFDVED (Cys-Cys-Ala-Leu-Asn-Asn-Pro-Phe-Phe-Asp-Val-Glu-Asp) or CCALNNKYDDVED (Cys-Cys-Ala-Leu-Asn-Asn-Lys-Tyr-Asp-Asp-Val-Glu-Asp), where the CALNN (Cys-Ala-Leu-Asn-Asn) fragment helps to stabilize AuNP suspension in aqueous media and the sequence of DVED (Asp-Glu-Val-Asp) can be cleaved by caspase-3. In addition, the PFF (Pro-Phe-Phe) or KYD (Lys-Tyr-Asp) was exposed and interacted via the hydrophobic or alternate negative and positive electro-interaction in the presence of caspase-3, inducing the aggregation of colloidal Au-peptides accompanied with the enhancement of SERS. It can be observed that the SERS-enhanced signals were correlated with the caspase-3 concentrations and the limit of detection can reach 1.5 ng mL^-1. Finally, this caspase-3-specified AuNP-peptide probe has been found to be a promising candidate for its application in the analysis of caspase-3 in living cells.

Balancing biofunctional and biomechanical properties using porous titanium reinforced by carbon nanotubes

Despite the well-known advantages of the titanium-based implant systems, they still lack an optimal balance between biofunctionality and mechanical strength, especially regarding the modulation of cellular response and a desired implant osseointegration. In this work, we fabricated a nanocomposite based on porous commercially pure grade 4 titanium (c.p. Ti) reinforced with carbon nanotubes (CNT) at 5% and 10% w/w, with the aim of obtaining a nanocomposite with lower stiffness compared to traditional titanium-based implants and with the mechanical strength and bioactivity owed by the CNT. Results obtained by scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy characterization showed that the CNT dispersed and incorporated into the porous c.p. Ti matrix. Interestingly, CNT were associated with a higher twining within neighbor Ti grains, which was indeed consistent with an increased in nano-hardness. Biological evaluation by MTT and Comet assay revealed that the nanocomposites did not induce genotoxicity and cytotoxicity on two different cells lines despite the presence of nickel at the surface. Accordingly, a purification step would be required before these CNT can be used for biomedical applications. Our results indicate that incorporation of CNT into porous c.p. Ti is a promising avenue to achieve an adequate balance between biofunctionality and mechanical strength in Ti-based scaffolds for tissue replacement. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 719-731, 2019.

Thermo-Sensitive Nanomaterials: Recent Advance in Synthesis and Biomedical Applications

Progress in nanotechnology has enabled us to open many new fronts in biomedical research by exploiting the peculiar properties of materials at the nanoscale. The thermal sensitivity of certain materials is a highly valuable property because it can be exploited in many promising applications, such as thermo-sensitive drug or gene delivery systems, thermotherapy, thermal biosensors, imaging, and diagnosis. This review focuses on recent advances in thermo-sensitive nanomaterials of interest in biomedical applications. We provide an overview of the different kinds of thermoresponsive nanomaterials, discussing their potential and the physical mechanisms behind their thermal response. We thoroughly review their applications in biomedicine and finally discuss the current challenges and future perspectives of thermal therapies.

Engineering functional inorganic-organic hybrid systems: advances in siRNA therapeutics

Cancer treatment still faces a lot of obstacles such as tumor heterogeneity, drug resistance and systemic toxicities. Beyond the traditional treatment modalities, exploitation of RNA interference (RNAi) as an emerging approach has immense potential for the treatment of various gene-caused diseases including cancer. The last decade has witnessed enormous research and achievements focused on RNAi biotechnology. However, delivery of small interference RNA (siRNA) remains a key challenge in the development of clinical RNAi therapeutics. Indeed, functional nanomaterials play an important role in siRNA delivery, which could overcome a wide range of sequential physiological and biological obstacles. Nanomaterial-formulated siRNA systems have potential applications in protection of siRNA from degradation, improving the accumulation in the target tissues, enhancing the siRNA therapy and reducing the side effects. In this review, we explore and summarize the role of functional inorganic-organic hybrid systems involved in the siRNA therapeutic advancements. Additionally, we gather the surface engineering strategies of hybrid systems to optimize for siRNA delivery. Major progress in the field of inorganic-organic hybrid platforms including metallic/non-metallic cores modified with organic shells or further fabrication as the vectors for siRNA delivery is discussed to give credit to the interdisciplinary cooperation between chemistry, pharmacy, biology and medicine.

MR and Iron Magnetic Nanoparticles. Imaging Opportunities in Preclinical and Translational Research

Ultrasmall superparamagnetic iron oxide nanoparticles and magnetic resonance imaging provide a non-invasive method to detect and label tumor cells. These nanoparticles exhibit unique properties of superparamagnetism and can be utilized as excellent probes for magnetic resonance imaging. Most work has been performed using a magnetic resonance scanner with high field strength up to 7 T. Ultrasmall superparamagnetic iron oxide nanoparticles may represent a suitable tool for labeling molecular probes that target specific tumor-associated markers for in vitro and in vivo detection by magnetic resonance imaging.

In our study, we demonstrated that magnetic resonance imaging at 1.5 T allows the detection of ultrasmall superparamagnetic iron oxide nanoparticle conjugated antibody specifically bound to human tumor cells in vitro and in vivo, and that the magnetic resonance signal intensity correlates with the concentration of ultrasmall superparamagnetic iron oxide nanoparticle antibody used and with the antigen density at the cell surface. The experiments were performed using two different means of targeting: direct and indirect magnetic tumor targeting. The imaging of tumor antigens using immunospecific contrast agents is a rapidly evolving field, which can potentially aid in early disease detection, monitoring of treatment efficacy, and drug development. Cell labeling by iron oxide nanoparticles has emerged as a potentially powerful tool to monitor trafficking of a large number of cells in the cell therapy field. We also studied the labeling of natural killer cells with iron nanoparticles to a level that would allow the detection of their signal intensity with a clinical magnetic resonance scanner at 1.5 T.

Magnetic resonance imaging and iron magnetic nanoparticles are able to increase the accuracy and the specificity of imaging and represent new imaging opportunities in preclinical and translational research.

Engineering of inorganic nanoparticles as magnetic resonance imaging contrast agents

Magnetic resonance imaging (MRI) is a highly valuable non-invasive imaging tool owing to its exquisite soft tissue contrast, high spatial resolution, lack of ionizing radiation, and wide clinical applicability. Contrast agents (CAs) can be used to further enhance the sensitivity of MRI to obtain information-rich images. Recently, extensive research efforts have been focused on the design and synthesis of high-performance inorganic nanoparticle-based CAs to improve the quality and specificity of MRI. Herein, the basic rules, including the choice of metal ions, effect of electron motion on water relaxation, and involved mechanisms, of CAs for MRI have been elucidated in detail. In particular, various design principles, including size control, surface modification (e.g. organic ligand, silica shell, and inorganic nanolayers), and shape regulation, to impact relaxation of water molecules have been discussed in detail. Comprehensive understanding of how these factors work can guide the engineering of future inorganic nanoparticles with high relaxivity. Finally, we have summarized the currently available strategies and their mechanism for obtaining high-performance CAs and discussed the challenges and future developments of nanoparticulate CAs for clinical translation in MRI.

Proteomic characterization of EL4 lymphoma-derived tumors upon chemotherapy treatment reveals potential roles for lysosomes and caspase-6 during tumor cell death in vivo

The murine mouse lymphoblastic lymphoma cell line (EL4) tumor model is an established in vivo apoptosis model for the investigation of novel cancer imaging agents and immunological treatments due to the rapid and significant response of the EL4 tumors to cyclophosphamide and etoposide combination chemotherapy. Despite the utility of this model system in cancer research, little is known regarding the molecular details of in vivo tumor cell death. Here, we report the first in-depth quantitative proteomic analysis of the changes that occur in these tumors upon cyclophosphamide and etoposide treatment in vivo. Using a label-free quantitative proteomic approach a total of 5838 proteins were identified in the treated and untreated tumors, of which 875 were determined to change in abundance with statistical significance. Initial analysis of the data reveals changes that may have been predicted, such as the downregulation of ribosomes, but demonstrates the robustness of the dataset. Analysis of the dataset also reveals the unexpected downregulation of caspase-3 and an upregulation of caspase-6 in addition to a global upregulation of lysosomal proteins in the bulk of the tumor.

Optoacoustic Detection of Early Therapy-Induced Tumor Cell Death Using a Targeted Imaging Agent

Purpose: The development of new treatments and their deployment in the clinic may be assisted by imaging methods that allow an early assessment of treatment response in individual patients. The C2A domain of Synaptotagmin-I (C2Am), which binds to the phosphatidylserine (PS) exposed by apoptotic and necrotic cells, has been developed as an imaging probe for detecting cell death. Multispectral optoacoustic tomography (MSOT) is a real-time and clinically applicable imaging modality that was used here with a near infrared (NIR) fluorophore-labeled C2Am to image tumor cell death in mice treated with a TNF-related apoptosis-inducing ligand receptor 2 (TRAILR2) agonist and with 5-fluorouracil (5-FU).Experimental Design: C2Am was labeled with a NIR fluorophore and injected intravenously into mice bearing human colorectal TRAIL-sensitive Colo205 and TRAIL-resistant HT-29 xenografts that had been treated with a potent agonist of TRAILR2 and in Colo205 tumors treated with 5-FU.Results: Three-dimensional (3D) MSOT images of probe distribution showed development of tumor contrast within 3 hours of probe administration and a signal-to-background ratio in regions containing dead cells of >10 after 24 hours. A site-directed mutant of C2Am that is inactive in PS binding showed negligible binding. Tumor retention of the active probe was strongly correlated (R2 = 0.97, P value < 0.01) with a marker of apoptotic cell death measured in histologic sections obtained post mortem.Conclusions: The rapid development of relatively high levels of contrast suggests that NIR fluorophore-labeled C2Am could be a useful optoacoustic imaging probe for detecting early therapy-induced tumor cell death in the clinic. Clin Cancer Res; 23(22); 6893-903. ©2017 AACR.

Rapid Imaging of Tumor Cell Death In Vivo Using the C2A Domain of Synaptotagmin-I

Cell death is an important target for imaging the early response of tumors to treatment. We describe here the validation of a phosphatidylserine-binding agent for detecting tumor cell death in vivo based on the C2A domain of synaptotagmin-I. Methods: The capability of near-infrared fluorophore-labeled and 99mTc- and 111In-labeled derivatives of C2Am for imaging tumor cell death, using planar near-infrared fluorescence imaging and SPECT, respectively, was evaluated in implanted and genetically engineered mouse models of lymphoma and in a human colorectal xenograft. Results: The fluorophore-labeled C2Am derivative showed predominantly renal clearance and high specificity and sensitivity for detecting low levels of tumor cell death (2%-5%). There was a significant correlation (R > 0.9, P < 0.05) between fluorescently labeled C2Am binding and histologic markers of cell death, including cleaved caspase-3, whereas there was no such correlation with a site-directed mutant of C2Am (iC2Am) that does not bind phosphatidylserine. 99mTc-C2Am and 111In-C2Am also showed favorable biodistribution profiles, with predominantly renal clearance and low nonspecific retention in the liver and spleen at 24 h after probe administration. 99mTc-C2Am and 111In-C2Am generated tumor-to-muscle ratios in drug-treated tumors of 4.3× and 2.2×, respectively, at 2 h and 7.3× and 4.1×, respectively, at 24 h after administration. Conclusion: Given the favorable biodistribution profile of 99mTc- and 111In-labeled C2Am, and their ability to produce rapid and cell death-specific image contrast, these agents have potential for clinical translation.

Magnetic resonance relaxation induced by superparamagnetic particles used as contrast agents in magnetic resonance imaging: a theoretical review

Superparamagnetic nanoparticles are used as contrast agents in magnetic resonance imaging and allow, for example, the detection of tumors or the tracking of stem cells in vivo. By producing magnetic inhomogeneities, they influence the nuclear magnetic relaxation times, which results in a darkening, on the image, of the region containing these particles. A great number of studies have been devoted to their magnetic properties, to their synthesis and to their influence on nuclear magnetic relaxation. The theoretical and fundamental understanding of the behavior of these particles is a necessary step in predicting their efficiency as contrast agents, or to be able to experimentally obtain some of their properties from a nuclear magnetic resonance measurement. Many relaxation models have been published, and choosing one of them is not always easy, many parameters and conditions have to be taken into account. Relaxation induced by superparamagnetic particles is generally attributed to an outersphere relaxation mechanism. Each model can only be used under specific conditions (motional averaging regime, static regime, high magnetic field, etc.) or for a particular sequence (Carr-Purcell-Meiboom-Gill, spin echo, free-induction decay, nuclear magnetic relaxation dispersion profile, etc.). The parameters included in the equations must be carefully interpreted. In some more complex conditions, simulations are necessary to be able to predict the relaxation rates. A good agreement is usually observed between the theoretical predictions and the experimental results, although some data still cannot be fully understood, such as the dependence of the transverse relaxation on the magnetic field. WIREs Nanomed Nanobiotechnol 2017, 9:e1468. doi: 10.1002/wnan.1468 For further resources related to this article, please visit the WIREs website.

The Effectiveness of Ferritin as a Contrast Agent for Cell Tracking MRI in Mouse Cancer Models

PURPOSE

We aimed to investigate the effectiveness of ferritin as a contrast agent and a potential reporter gene for tracking tumor cells or macrophages in mouse cancer models.

MATERIALS AND METHODS

Adenoviral human ferritin heavy chain (Ad-hFTH) was administrated to orthotopic glioma models and subcutaneous colon cancer mouse models using U87MG and HCT116 cells, respectively. Brain MR images were acquired before and daily for up to 6 days after the intracranial injection of Ad-hFTH. In the HCT116 tumor model, MR examinations were performed before and at 6, 24, and 48 h after intratumoral injection of Ad-hFTH, as well as before and every two days after intravenous injection of ferritin-labeled macrophages. The contrast effect of ferritin in vitro was measured by MR imaging of cell pellets. MRI examinations using a 7T MR scanner comprised a T1-weighted (T1w) spin-echo sequence, T2-weighted (T2w) relaxation enhancement sequence, and T2*-weighted (T2*w) fast low angle shot sequence.

RESULTS

Cell pellet imaging of Ad-hFTH in vitro showed a strong negatively enhanced contrast in T2w and T2*w images, presenting with darker signal intensity in high concentrations of Fe. T2w images of glioma and subcutaneous HCT116 tumor models showed a dark signal intensity around or within the Ad-hFTH tumor, which was distinct with time and apparent in T2*w images. After injection of ferritin-labeled macrophages, negative contrast enhancement was identified within the tumor.

CONCLUSION

Ferritin could be a good candidate as an endogenous MR contrast agent and a potential reporter gene that is capable of maintaining cell labeling stability and cellular safety.

Magnetic Nanoparticle Facilitated Drug Delivery for Cancer Therapy with Targeted and Image-Guided Approaches

With rapid advances in nanomedicine, magnetic nanoparticles (MNPs) have emerged as a promising theranostic tool in biomedical applications, including diagnostic imaging, drug delivery and novel therapeutics. Significant preclinical and clinical research has explored their functionalization, targeted delivery, controllable drug release and image-guided capabilities. To further develop MNPs for theranostic applications and clinical translation in the future, we attempt to provide an overview of the recent advances in the development and application of MNPs for drug delivery, specifically focusing on the topics concerning the importance of biomarker targeting for personalized therapy and the unique magnetic and contrast-enhancing properties of theranostic MNPs that enable image-guided delivery. The common strategies and considerations to produce theranostic MNPs and incorporate payload drugs into MNP carriers are described. The notable examples are presented to demonstrate the advantages of MNPs in specific targeting and delivering under image guidance. Furthermore, current understanding of delivery mechanisms and challenges to achieve efficient therapeutic efficacy or diagnostic capability using MNP-based nanomedicine are discussed.

Direct quantitative 13 C-filtered 1 H magnetic resonance imaging of PEGylated biomacromolecules in vivo

PURPOSE

¹ H MRI is an established diagnostic method that generally relies on detection of water. Imaging specific macromolecules is normally accomplished only indirectly through the use of paramagnetic tags, which alter the water signal in their vicinity. We demonstrate a new approach in which macromolecular constituents, such as proteins and drug delivery systems, are observed directly and quantitatively in vivo using ¹ H MRI of ¹³ C-labeled poly(ethylene glycol) (¹³ C-PEG) tags.

METHODS

Molecular imaging of ¹³ C-PEG-labeled species was accomplished by incorporating a modified heteronuclear multiple quantum coherence filter into a gradient echo imaging sequence. We demonstrate the approach by monitoring the real-time distribution of ¹³ C-PEG and ¹³ C-PEGylated albumin injected into the hind leg of a mouse.

RESULTS

Filtering the ¹ H PEG signal through the directly coupled ¹³ C nuclei largely eliminates background water and fat signals, thus enabling the imaging of molecules using ¹ H MRI.

CONCLUSION

PEGylation is widely employed to enhance the performance of a multitude of macromolecular therapeutics and drug delivery systems, and ¹³ C-filtered ¹ H MRI of ¹³ C-PEG thus offers the possibility of imaging and quantitating their distribution in living systems in real time. Magn Reson Med 77:1553-1561, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Utilization of nanoparticle technology in rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is one of the common and severe autoimmune diseases related to joints. This chronic autoimmune inflammatory disease, leads to functional limitation and reduced quality of life, since as there is bone and cartilage destruction, joint swelling and pain. Current advances and new treatment approaches have considerably postponed disease progression and improved the quality of life for many patients. In spite of major advances in therapeutic options, restrictions on the routes of administration and the necessity for frequent and long-term dosing often result in systemic adverse effects and patient non-compliance. Unlike usual drugs, nanoparticle systems are planned to deliver therapeutic agents especially to inflamed synovium, so avoiding systemic and unpleasant effects. The present review discusses about some of the most successful drugs in RA therapy and their side effects and also focuses on key design parameters of RA-targeted nanotechnology-based strategies for improving RA therapies.