Non-invasive quantitative imaging of hepatocellular carcinoma growth in mice by micro-CT using liver-targeted iodinated nano-emulsions

CT and X-ray contrast agents: Current clinical challenges and the future of contrast

Computed tomography (CT) is a powerful and widely used imaging technique in modern medicine. However, it often requires the use of contrast agents to visualize structures with similar radiographic density. Unfortunately, current clinical contrast agents (CAs) for CT have remained largely unchanged for decades and come with several significant drawbacks, including serious nephrotoxicity and short circulation half-lives. The next generation of CT radiocontrast agents should strive to be long-circulating, non-toxic, and non-immunogenic. Nanoparticle contrast agents have shown promise in recent years and are likely to comprise the majority of next-generation CT contrast agents. This review highlights the fundamental mechanism and background of X-ray and contrast agents. It also focuses on the challenges associated with current clinical contrast agents and provides a brief overview of potential future agents that are based on various materials such as lipids, polymers, dendrimers, metallic, and non-metallic inorganic nanoparticles (NPs). STATEMENT OF SIGNIFICANCE: We realized a need for clarification on a number of concerns related to the use of iodinated contrast material as debates regarding the safety of these agents with patients with kidney disease, shellfish allergies, and thyroid dysfunction remain ongoing in medical practice. This review was partially inspired by debates witnessed in medical practice regarding outdated misconceptions of contrast material that warrant clarification in translational and clinical arenas. Given that conversation around currently available agents is at somewhat of a high water mark, and nanoparticle research has now reached an unprecedented number of readers, we find that this review is timely and unique in the context of recent discussions in the field.

Advances of Nanotechnology in the Diagnosis and Treatment of Hepatocellular Carcinoma

Nanotechnology has emerged as a promising technology in the field of hepatocellular carcinoma (HCC), specifically in the implementation of diagnosis and treatment strategies. Nanotechnology-based approaches, such as nanoparticle-based contrast agents and nanoscale imaging techniques, have shown great potential for enhancing the sensitivity and specificity of HCC detection. These approaches provide high-resolution imaging and allow for the detection of molecular markers and alterations in cellular morphology associated with HCC. In terms of treatment, nanotechnology has revolutionized HCC therapy by enabling targeted drug delivery, enhancing therapeutic efficacy, and minimizing off-target effects. Nanoparticle-based drug carriers can be functionalized with ligands specific to HCC cells, allowing for selective accumulation of therapeutic agents at the tumor site. Furthermore, nanotechnology can facilitate combination therapy by co-encapsulating multiple drugs within a single nanoparticle, allowing for synergistic effects and overcoming drug resistance. This review aims to provide an overview of recent advances in nanotechnology-based approaches for the diagnosis and treatment of HCC. Further research is needed to optimize the design and functionality of nanoparticles, improve their biocompatibility and stability, and evaluate their long-term safety and efficacy. Nonetheless, the integration of nanotechnology in HCC management holds great promise and may lead to improved patient outcomes in the future.

Radiopaque Iodosilane-Coated Lipid Hybrid Nanoparticle Contrast Agent for Dual-Modality Ultrasound and X-ray Bioimaging

Here, we report the synthesis of robust hybrid iodinated silica-lipid nanoemulsions (HSLNEs) for use as a contrast agent for ultrasound and X-ray applications. We engineered iodinated silica nanoparticles (SNPs), lipid nanoemulsions, and a series of HSLNEs by a low-energy spontaneous nanoemulsification process. The formation of a silica shell requires sonication to hydrolyze and polymerize/condensate the iodomethyltrimethoxysilane at the oil/water interface of the nanoemulsion droplets. The resulting nanoemulsions (NEs) exhibited a homogeneous spherical morphology under transmission electron microscopy. The particles had diameters ranging from 20 to 120 nm with both negative and positive surface charges in the absence and presence of cetyltrimethylammonium bromide (CTAB), respectively. Unlike CTAB-coated nanoformulations, the CTAB-free NEs showed excellent biocompatibility in murine RAW macrophages and human U87-MG cell lines in vitro. The maximum tolerated dose assessment was evaluated to verify their safety profiles in vivo. In vitro X-ray and ultrasound imaging and in vivo computed tomography were used to monitor both iodinated SNPs and HSLNEs, validating their significant contrast-enhancing properties and suggesting their potential as dual-modality clinical agents in the future.

Nanotechnology strategies for hepatocellular carcinoma diagnosis and treatment

Hepatocellular carcinoma (HCC) is a common malignancy threatening human health, and existing diagnostic and therapeutic techniques are facing great challenges. In the last decade or so, nanotechnology has been developed and improved for tumor diagnosis and treatment. For example, nano-intravenous injections have been approved for malignant perivascular epithelioid cell tumors. This article provides a comprehensive review of the applications of nanotechnology in HCC in recent years: (I) in radiological imaging, magnetic resonance imaging (MRI), fluorescence imaging (FMI) and multimodality imaging. (II) For diagnostic applications in HCC serum markers. (III) As embolic agents in transarterial chemoembolization (TACE) or directly as therapeutic drugs. (IV) For application in photothermal therapy and photodynamic therapy. (V) As carriers of chemotherapeutic drugs, targeted drugs, and natural plant drugs. (VI) For application in gene and immunotherapy. Compared with the traditional methods for diagnosis and treatment of HCC, nanoparticles have high sensitivity, reduce drug toxicity and have a long duration of action, and can also be combined with photothermal and photodynamic multimodal combination therapy. These summaries provide insights for the further development of nanotechnology applications in HCC.

Ultrahigh resolution whole body photon counting computed tomography as a novel versatile tool for translational research from mouse to man

X-ray computed tomography (CT) is a cardinal tool in clinical practice. It provides cross-sectional images within seconds. The recent introduction of clinical photon-counting CT allowed for an increase in spatial resolution by more than a factor of two resulting in a pixel size in the center of rotation of about 150 µm. This level of spatial resolution is in the order of dedicated preclinical micro-CT systems. However so far, the need for different dedicated clinical and preclinical systems often hinders the rapid translation of early research results to applications in men. This drawback might be overcome by ultra-high resolution (UHR) clinical photon-counting CT unifying preclinical and clinical research capabilities in a single machine. Herein, the prototype of a clinical UHR PCD CT (SOMATOM CounT, Siemens Healthineers, Forchheim, Germany) was used. The system comprises a conventional energy-integrating detector (EID) and a novel photon-counting detector (PCD). While the EID provides a pixel size of 0.6 mm in the centre of rotation, the PCD provides a pixel size of 0.25 mm. Additionally, it provides a quantification of photon energies by sorting them into up to four distinct energy bins. This acquisition of multi-energy data allows for a multitude of applications, e.g. pseudo-monochromatic imaging. In particular, we examine the relation between spatial resolution, image noise and administered radiation dose for a multitude of use-cases. These cases include ultra-high resolution and multi-energy acquisitions of mice administered with a prototype bismuth-based contrast agent (nanoPET Pharma, Berlin, Germany) as well as larger animals and actual patients. The clinical EID provides a spatial resolution of about 9 lp/cm (modulation transfer function at 10%, MTF_10%) while UHR allows for the acquisition of images with up to 16 lp/cm allowing for the visualization of all relevant anatomical structures in preclinical and clinical specimen. The spectral capabilities of the system enable a variety of applications previously not available in preclinical research such as pseudo-monochromatic images. Clinical ultra-high resolution photon-counting CT has the potential to unify preclinical and clinical research on a single system enabling versatile imaging of specimens and individuals ranging from mice to man.

Ultrasound and nanomaterial: an efficient pair to fight cancer

Ultrasounds are often used in cancer treatment protocols, e.g. to collect tumor tissues in the right location using ultrasound-guided biopsy, to image the region of the tumor using more affordable and easier to use apparatus than MRI and CT, or to ablate tumor tissues using HIFU. The efficacy of these methods can be further improved by combining them with various nano-systems, thus enabling: (i) a better resolution of ultrasound imaging, allowing for example the visualization of angiogenic blood vessels, (ii) the specific tumor targeting of anti-tumor chemotherapeutic drugs or gases attached to or encapsulated in nano-systems and released in a controlled manner in the tumor under ultrasound application, (iii) tumor treatment at tumor site using more moderate heating temperatures than with HIFU. Furthermore, some nano-systems display adjustable sizes, i.e. nanobubbles can grow into micro-bubbles. Such dual size is advantageous since it enables gathering within the same unit the targeting properties of nano bubbles via EPR effect and the enhanced ultrasound contrasting properties of micro bubbles. Interestingly, the way in which nano-systems act against a tumor could in principle also be adjusted by accurately selecting the nano-system among a large choice and by tuning the values of the ultrasound parameters, which can lead, due to their mechanical nature, to specific effects such as cavitation that are usually not observed with purely electromagnetic waves and can potentially help destroying the tumor. This review highlights the clinical potential of these combined treatments that can improve the benefit/risk ratio of current cancer treatments.

Antitumor effects of cadmium against diethylnitrosamine-induced liver tumors in mice

Cadmium (Cd) has been reported to exhibit antitumor effects against chemically induced liver tumors. However, the antitumor effects of Cd are not completely understood. Metallotherapy, the use of a toxic metal to attack liver tumors, could be a viable strategy. In the present study, 8-week old, male, C57BL/6 mice were administered injections of diethylnitrosamine (DEN) (90 mg/kg, and then 50 mg/kg 2 weeks later), followed by liver tumor promotion with carbon tetrachloride. Cadmium chloride was administered in the drinking water (1000 ppm) from 21–40 weeks after DEN initiation. Body weights were recorded and liver tumor formation was monitored via ultrasound. At the end of experiments, livers were removed, weighed, and the tumor incidence, tumor numbers and tumor size scores were recorded. Liver histology and metallothionein (MT) immunostaining were performed. After DEN injection, animal body weight decreased, and then slowly recovered with time. Cd treatment did not affect animal body weight gain. Ultrasound analysis detected liver tumors 35 weeks after DEN injection, and the mice were necropsied at 40 weeks. Liver/body weight ratios increased in the DEN and DEN + Cd groups. Cd treatment decreased the tumor incidence (71 vs. 17%), tumor numbers (15 vs. 2) and tumor scores (22 vs. 3) when compared with the DEN only group. Histopathology showed hepatocyte degeneration in all groups, and immunohistochemistry showed MT-deficiency in the liver tumors, while MT staining was intensified in the surrounding tissues. Reverse transcription-quantitative PCR showed increases in α-fetoprotein level in DEN-treated livers, and increases in MT-2 and tumor necrosis factor α (TNFα) levels in Cd-treated livers. Thus, it was concluded that Cd is effective in the suppression of DEN-induced liver tumors, and that the mechanisms may be related to MT-deficiency in tumors and the induction of TNFα to kill tumor cells.

Longitudinal Imaging of Liver Cancer Using MicroCT and Nanoparticle Contrast Agents in CRISPR/Cas9-Induced Liver Cancer Mouse Model

Introduction:

Micro-computed tomography with nanoparticle contrast agents may be a suitable tool for monitoring the time course of the development and progression of tumors. Here, we suggest a practical and convenient experimental method for generating and longitudinally imaging murine liver cancer models.

Methods:

Liver cancer was induced in 6 experimental mice by injecting clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats-associated protein 9 plasmids causing mutations in genes expressed by hepatocytes. Nanoparticle agents are captured by Kupffer cells and detected by micro-computed tomography, thereby enabling longitudinal imaging. A total of 9 mice were used for the experiment. Six mice were injected with both plasmids and contrast, 2 injected with contrast alone, and one not injected with either agent. Micro-computed tomography images were acquired every 2- up to 14-weeks after cancer induction.

Results:

Liver cancer was first detected by micro-computed tomography at 8 weeks. The mean value of hepatic parenchymal attenuation remained almost unchanged over time, although the standard deviation of attenuation, reflecting heterogeneous contrast enhancement of the hepatic parenchyma, increased slowly over time in all mice. Histopathologically, heterogeneous distribution and aggregation of Kupffer cells was more prominent in the experimental group than in the control group. Heterogeneous enhancement of hepatic parenchyma, which could cause image quality deterioration and image misinterpretation, was observed and could be due to variation in Kupffer cells distribution.

Conclusion:

Micro-computed tomography with nanoparticle contrast is useful in evaluating the induction and characteristics of liver cancer, determining appropriate size of liver cancer for testing, and confirming therapeutic response.

A critical review of synthesis procedures, applications and future potential of nanoemulsions

Applications of nanotechnology in various spheres have increased manifold as it offers solution to unsolved problems with higher effectiveness. Nanoemulsions are one such system that are widely studied and have a very promising potential in solving various issues as those encountered in delivery of drugs, pesticides or any other biologically potent substance. Apart from this, nanoemulsions have wide applications in the field of food, cosmetics, skincare and agriculture. In this review, we have discussed and compared the methods of nanoemulsion preparation and various methods of synthesis, along with few major applications in various fields of science and technology. We sincerely hope that this review will help to understand the different aspects of nanoemulsions and help us to explore its potent applications in various fields.

Multiscale Live Imaging Using Förster Resonance Energy Transfer (FRET) for Evaluating the Biological Behavior of Nanoparticles as Drug Carriers

To develop targeted drug delivery systems using nanoparticles for treating various diseases, the evaluation of nanoparticle behavior in biological environments is necessary. In the present study, the biological behavior of polymeric nanoparticles was directly traced in living mice and cells. The dissociation of nanoparticles was detected by Förster resonance energy transfer (FRET) imaging. DiR and DiD were encapsulated in the nanoparticles for near-infrared FRET imaging, and they were traced using in vivo FRET imaging and intravital FRET imaging at the whole-body and tissue scales, respectively. In vivo FRET imaging revealed that the nanoparticles dissociated over time following intravenous administration. Intravital FRET imaging revealed that the nanoparticles dissociated in the liver and blood vessels following intravenous administration. DiI and DiO were encapsulated in nanoparticles for FRET imaging using confocal microscopy, and they were traced using in vitro FRET imaging in HepG2 cells. In vitro FRET imaging revealed that the nanoparticles dissociated and released fluorescent dyes that distributed in the cell membrane. Finally, live imaging was performed using FRET at the whole-body, tissue, and cellular scales. This method is suitable for obtaining information regarding the biological kinetic properties of nanoparticles and their use in targeted drug delivery.

Lipid-based nanoparticle technologies for liver targeting

Liver diseases such as hepatitis, cirrhosis, and hepatocellular carcinoma are global health problems accounting for approximately 800 million cases and over 2 million deaths per year worldwide. Major drawbacks of standard pharmacological therapies are the inability to deliver a sufficient concentration of a therapeutic agent to the diseased liver, and nonspecific drug delivery leading to undesirable systemic side effects. Additionally, depending on the specific liver disease, drug delivery to a subset of liver cells is required. In recent years, lipid nanoparticles have been developed to passively and actively target drugs to the liver. The success of this approach has been highlighted by the FDA-approval of the first liver-targeting lipid nanoparticle, ONPATTRO, in 2018 and many other promising candidate technologies are expected to follow. This review summarizes recent developments of various lipid-based liver-targeting technologies, namely solid-lipid nanoparticles, liposomes, niosomes and micelles, and discusses the challenges and future perspectives in this field.

Tracking Dynamics of Spontaneous Tumors in Mice Using Photon-Counting Computed Tomography

Computed tomography is a powerful medical imaging modality for longitudinal studies in cancer to follow neoplasia progression and evaluate anticancer therapies. Here, we report the generation of a photon-counting micro-computed tomography (PC-CT) method based on hybrid pixel detectors with enhanced sensitivity and precision of tumor imaging. We then applied PC-CT for longitudinal imaging in a clinically relevant liver cancer model, the Alb-R26^Met mice, and found a remarkable heterogeneity in the dynamics for tumors at the initiation phases. Instead, the growth curve of evolving tumors exhibited a comparable exponential growth, with a constant doubling time. Furthermore, longitudinal PC-CT imaging in mice treated with a combination of MEK and BCL-XL inhibitors revealed a drastic tumor regression accompanied by a striking remodeling of macrophages in the tumor microenvironment. Thus, PC-CT is a powerful system to detect cancer initiation and progression, and to monitor its evolution during treatment.

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Development of photon-counting micro-computed tomography (PC-CT) with hybrid pixels

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PC-CT allows longitudinal imaging of tumor dynamics in mouse cancer models

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RTK-driven tumors are heterogeneous at onset, but grow steadily during progression

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MEK + BCL-XL targeting leads to tumor regression and microenvironment remodeling

Ultrasound-Guided Approaches to Improve Orthotopic Mouse Xenograft Models for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the second leading cause of cancer death worldwide. While curative approaches for early stage HCC exist, effective treatment options for advanced HCC are lacking. Furthermore, there are no efficient chemopreventive strategies to limit HCC development once cirrhosis is established. One challenge for drug development is unsatisfactory animal models. In this article, we describe an orthotopic xenograft mouse model of human liver cancer cell lines through image-guided injection into the liver. This technique provides a less invasive yet highly efficient approach to engraft human HCC into mouse liver. Similarly, image-guided injections are used to deliver chemotherapeutics locally, enabling reduction in potential systemic adverse effects, while reducing the required dose for a therapeutic effect. In summary, this image-guided strategy provides a novel and convenient approach to improve current HCC mouse models. © 2019 The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Development of Severe Combined Immunodeficient (SCID) Pig Models for Translational Cancer Modeling: Future Insights on How Humanized SCID Pigs Can Improve Preclinical Cancer Research

Within the last decade there have been several severe combined immunodeficient (SCID) pig models discovered or genetically engineered. The animals have mutations in ARTEMIS, IL2RG, or RAG1/2 genes, or combinations thereof, providing SCID pigs with NK cells, but deficient in T and B cells, or deficient in NK, T, and B cells for research studies. Biocontainment facilities and positive pressure isolators are developed to limit pathogen exposure and prolong the life of SCID pigs. Raising SCID pigs in such facilities allows for completion of long-term studies such as xenotransplantation of human cells. Ectopically injected human cancer cell lines develop into tumors in SCID pigs, thus providing a human-sized in vivo model for evaluating imaging methods to improve cancer detection and therapeutic research and development. Immunocompromised pigs have the potential to be immunologically humanized by xenotransplantation with human hematopoietic stem cells, peripheral blood leukocytes, or fetal tissue. These cells can be introduced through various routes including injection into fetal liver or the intraperitoneal (IP) space, or into piglets by intravenous, IP, and intraosseous administration. The development and maintenance of transplanted human immune cells would be initially (at least) dependent on immune signaling from swine cells. Compared to mice, swine share higher homology in immune related genes with humans. We hypothesize that the SCID pig may be able to support improved engraftment and differentiation of a wide range of human immune cells as compared to equivalent mouse models. Humanization of SCID pigs would thus provide a valuable model system for researchers to study interactions between human tumor and human immune cells. Additionally, as the SCID pig model is further developed, it may be possible to develop patient-derived xenograft models for individualized therapy and drug testing. We thus theorize that the individualized therapeutic approach would be significantly improved with a humanized SCID pig due to similarities in size, metabolism, and physiology. In all, porcine SCID models have significant potential as an excellent preclinical animal model for therapeutic testing.

Recent Advances in Polyesters for Biomedical Imaging

Several synthetic materials exhibiting contrast imaging properties have become vital to the field of biomedical imaging. Polymeric biomaterials and metals are commonly used imaging agents and can assist in the monitoring of therapy response, migration, degradation, changes in morphology, defects, and image-guided surgery. In comparison to metals, most bio and synthetic polymers lack inherent imaging properties. Polymeric biomaterials, specifically polyesters, have gained a considerable amount of attention due to their unique properties including biocompatibility, biodegradation, facile synthesis, and modification capability. Polyester implants and nanomaterials are available on the market or are in clinical trials for many applications including: dental implants, cranio-maxilofacial implants, soft tissue sutures and staples, abdominal wall repair, tendon and ligament reconstruction, fracture fixation devices, and coronary drug eluting stents. This review aims to provide a summary of the recent developments of polyesters with bioimaging contrast properties. The three main approaches to prepare bioimaging polyesters (coating, encapsulation, and functionalization) are discussed in depth. Furthermore, commonly used imaging modalities including X-ray computed tomography, magnetic resonance imaging, ultrasound, fluorescence, and radionucleotide polyester contrast agents are highlighted. In each section, examples of impactful bioimaging polyesters in the five major imaging modalities are evaluated.