Embolization therapy with microspheres for the treatment of liver cancer: State-of-the-art of clinical translation

Dual-miRNA guided in-vivo imaging and multimodal nanomedicine approaches for precise hepatocellular carcinoma differentiation and synergistic cancer theranostics using DNA hairpins and dual-ligand functionalized zirconium-MOF nanohybrids

As one of the most common and heterogeneous liver malignancies, hepatocellular carcinoma (HCC) remains a significant clinical challenge due to the lack of biomarkers for early diagnosis, challenges in accurate subtyping, and limitations of current therapeutic strategies with poor efficacy. Herein, based on DNA hairpin probes and dual-ligand zirconium (Zr)-based metal-organic frameworks (DMOFs), the multifunctional nanohybrids (DMOF@MnCO@CuS@Hairpin probe, DMCH) were developed to overcome these diagnostic and therapeutic obstacles. Two improved DNA molecular beacons and APE1 enzyme within HCC cells were utilized for sensitive miRNA imaging in vivo with high accuracy to differentiate HCC subtypes precisely. Furthermore, this "all-in-one" theranostic platform not only facilitates the generation of active oxygen species and conversion of near-infrared light into heat, but also releases carbon monoxide to inhibit the expression of HSP70 protein to improve photothermal (PTT) therapy efficiency during laser radiation, which enables PTT, photodynamic (PDT), chemodynamic (CDT), and gas therapy (GAT) for HCC treatment simultaneously. The developed nano-theranostics platform provides a novel way for efficient early screening, diagnosis, and intervention of HCC, and paves the path for future "bench-to-bedside" design of theranostics.

Protein-based embolic agent loaded with ethiodized oil for targeted tumor vascular embolization

Tumor embolization therapy often involves complex procedures and poses challenges for physicians, especially with radiological imaging guidance. Inspired by physiological processes of misfolded protein aggregation and thrombus formation, we developed a protein-based embolic agent using ethiodized oil and human serum albumin for targeted tumor embolization. By occupying the hydrophobic cavity of albumin and disrupting its refolding process, these ethiodized oil bound human serum albumin nanoparticles (Oil@HSA NPs) achieve spontaneous aggregation and size growth at high concentrations, a unique advantage over conventional phospholipid nanoparticles. When combined with bacterium-induced coagulation in tumor vessels, Oil@HSA NPs selectively accumulate at tumor sites, blocking blood flow and significantly inhibiting tumor growth. This study introduces a practical and innovative approach to tumor embolization, offering a streamlined and effective alternative for vascular targeting in cancer therapy.

Comparison of Liquid with Particle Embolics in a Translational Rat Model of Hepatocellular Carcinoma: Histologic and Radiographic Responses

PURPOSE

To compare the effectiveness of transarterial embolization (TAE) using a liquid embolic (LE) with that of TAE using a particle embolic (PE) based on radiographic and histologic responses in a translational rat model of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

HCC was induced in Wistar rats using diethylnitrosamine. Tumor response was determined through Response Evaluation Criteria in Solid Tumors applied to T2-weighted magnetic resonance (MR) imaging scans. Tumor necrosis and hypoxia were assessed through hematoxylin and eosin and pimonidazole staining, respectively. Statistical analyses were performed using chi-square tests, Kaplan-Meier estimates, logistic regression, and 1-way analysis of variance, with significance set at P < .05.

RESULTS

Twenty-nine rats were randomized to TAE with LE (n = 13), PE (n = 13), or sham (n = 3). LE TAE demonstrated a significantly higher objective response rate (83%) compared with PE TAE (28%; χ2 = 11.25; P = .0008). Complete responses were observed in 50% of the LE-treated tumors versus 10% in the PE-treated group. LE TAE prolonged local progression-free survival (hazard ratio, 0.31; P = .032). Histologic analysis of an additional 16 rats randomized to TAE with LE (n = 7), PE (n = 6), or sham (n = 3) showed greater necrosis in LE-treated tumors compared to PE-treated tumors. LE induced a significantly greater reduction in viable tumor tissue (P = .009) and proportionally larger necrotic and necrotic + hypoxic tissue areas compared with PE (P = .003).

CONCLUSIONS

LE significantly enhanced the therapeutic effectiveness of TAE in a rat model of HCC compared with PE. These results highlight the potential of LEs to improve ischemia and necrosis, thereby offering a promising option for improving the effectiveness of embolization for HCC treatment.

Recent progress in polysaccharide microsphere-based hemostatic material for intravascular and extravascular hemostasis: A review

Hemorrhage, a common consequence of diseases, surgical procedures, and traffic accidents, poses a significant threat to public health. Effective hemostasis is crucial for patient survival and prognosis, particular in case of internal bleeding. While polysaccharide microsphere-based hemostatic materials have gained clinical acceptance due to their effectiveness, good biocompatibility, and versatility in both intravascular and extravascular hemostasis, they are limited by their single function and insufficient hemostatic properties. Recently, booming developments have been witnessed in microsphere-based biomaterials to achieve a combination therapy for hemostasis. This review first examines the fundamentals of coagulation process, hemostatic mechanisms, and microsphere fabrication techniques. We then discuss the latest investigations in functionalized microsphere-based hemostatic materials for controlling intravascular and extravascular hemorrhage, focusing on design strategies, hemostatic properties, and clinical implementation. Finally, we also propose some limitations and challenges of these hemostatic materials, aiming to provide valuable insights for future research in novel polysaccharide microsphere-based biomaterial.

Using ultrasound and microbubble to enhance the effects of conventional cancer therapies in clinical settings

It has been demonstrated in preclinical research that the administration of microbubbles with ultrasound can augment the proapoptotic sphingolipid pathway and enhance chemotherapy or radiation therapy-induced vascular endothelial disruption resulting in enhanced tumor cell death. Specifically, ultrasound-stimulated microbubbles (USMB) can increase blood vessel permeability facilitating the release of therapeutic substances in the target area. USMB can also serve as a potential radiation enhancing therapy as USMB exposure increases tumor cell death significantly as observed in preclinical models. Clinical studies have found the combination of USMB and these existing cancer therapies to be safe and also to be associated with greater tumor responses. USMB-based treatment can be applicable in a clinical setting using either ultrasound imaging or magnetic resonance imaging (MRI) guidance for precise treatment. In the latter, the ultrasound device is integrated into the MRI system platform for sonication to facilitate microbubble stimulation. In this review, we concisely present findings related to USMB and existing cancer therapies (chemotherapy and radiation therapy) in clinical trial settings. The possible underlying mechanism involved in USMB-enhanced chemotherapy or radiotherapy enhancement is also discussed. Lastly, the study concludes with some limitations and an examination of the future direction of these combined therapies.

Ultrafine fiber-mediated transvascular interventional photothermal therapy using indocyanine green for precision embolization treatment

Photothermal treatment has attracted immense interest as a promising approach for biomedical applications such as cancer ablation, yet its effectiveness is often limited by insufficient laser penetration and challenges in achieving efficient targeting of photothermal agents. Here we developed a transvascular interventional photothermal therapy (Ti-PTT), which employed a small-sized microcatheter (outer diameter: 0.60 mm, 1.8 Fr) equipped with an ultrafine optical fiber (diameter: 100 μm) capable of simultaneously delivering photothermal agents while performing 808 nm laser irradiation via an endovascular route. Specifically, we employed two types of indocyanine green (ICG)-based photothermal agents, i.e. ICG solution serving as a purely photothermal agent and ICG-ethiodized oil (ICG-EO) emulsion acting as a radiopaque photothermal embolic agent. Using the customized microcatheter with the ICG solution, both proximal and distal embolization were able to be performed in a rat liver model. Compared to the ICG solution, the ICG-EO emulsion dramatically enhanced the ICG retention time, enabling a photothermally triggered precision vascular blockade to induce local embolization of large tissue volumes in a rat kidney model with an unfavorable ICG leakage rate. The Ti-PTT paves the way to broadening the potential applications of photothermal therapy through combination with clinical intervention-based approaches.

In Situ Forming Supramolecular Nanofiber Hydrogel as a Biodegradable Liquid Embolic Agent for Postembolization Tissue Remodeling

Embolic agents have been widely used to treat blood vessel abnormalities in interventional radiology as a minimally invasive procedure. However, only a few biodegradable liquid embolic agents exhibit high embolization performance, biodegradability, and operability. Herein, the design of in situ-forming supramolecular nanofiber (SNF) hydrogels is reported as biodegradable liquid embolic agents with the assistance of Bayesian optimization through an active learning pipeline. Chemically modified gelatin with hydrogen-bonding moieties produces fibrin-inspired nanofiber-based hydrogels with a high blood coagulation capacity. The low viscosity of the SNF hydrogels makes them injectable using a microcatheter, and the hydrogel shows sufficient tissue adhesion to the blood vessel walls and very weak adhesion to the catheter tubes. Moreover, the SNF hydrogels exhibit high blood compatibility, cytocompatibility, cell-adhesive properties, and biodegradability (in vitro and in vivo). Intravascularly delivered SNF hydrogels induce embolization of rat femoral arteries. This biodegradable liquid embolic agent could be a powerful tool for interventional radiology in the treatment of various diseases, including aortic aneurysm stent grafting, gynecological diseases, and liver cancer.

Whey Protein-Based Hydrogel Microspheres for Endovascular Embolization

Transarterial embolization (TAE) is an image-guided, minimally invasive procedure for treating various clinical conditions by delivering embolic agents to occlude diseased arteries. Conventional embolic agents focus on vessel occlusion but can cause unintended long-term inflammation and ischemia in healthy tissues. Next-generation embolic agents must exhibit biocompatibility, biodegradability, and effective drug delivery, yet some degradable microspheres degrade too quickly, leading to the potential migration of fragments into distal blood vessels causing off-target embolization. This study presents the development of whey protein hydrogel microspheres (WPHMS) made from methacrylated whey protein, which successfully withstood terminal sterilization by autoclaving. In vitro characterization revealed that sterile WPHMS are suspensible in iodine-containing contrast agents, injectable through standard catheters and microcatheters, and can be temporarily compressed by at least 12.8% without permanent deformation. Cytocompatibility was confirmed using NIH/3T3 cells, while enzymatic degradation was assessed with proteinase K. Preliminary drug loading and release studies demonstrated the potential for doxorubicin hydrochloride (Dox-HCl) as a model drug. In vivo assessments in rabbit renal models showed that WPHMS successfully occluded the renal arteries in the acute study and remained in the renal arteries for up to 3 weeks in the chronic study, with signs of early degradation. Fibrous tissue anchored the degraded residues, minimizing the risk of migration. These findings indicate that WPHMS holds significant promise as endovascular embolization agents for minimally invasive therapies.

Superselective embolic particle guidance in vessel networks via shape-adaptive acoustic manipulation

Interventional embolization has been widely used as a clinical cancer therapy, which deactivates the tumors by occluding their blood supply vessels. However, conventional methods lack active control over the embolic particles, thus having a limited selectivity of millimeter-scale vessels and the issue of missing embolization. Here, we propose an ultrasound-based method for embolic particle control in submillimeter vessels. The biocompatible ultrasound generated from an extrasomatic source can transmit through biological tissues, and exert forces on the intravital embolic particles. We show that the particles, influenced by these forces, are steerable to the target branch at vascular bifurcations. By modulating the ultrasound to adapt the vascular bifurcation distribution, the particles flowing in the micro-vessel networks are steered to the target branch and embolize it. The acoustic steering within ex vivo and in vivo models both verify the potential of this non-invasive particle control for precise and safe interventional therapy.

Biomaterials enhancing localized cancer therapy activated anti-tumor immunity: a review

Localized cancer therapies such as radiotherapy, phototherapy, and chemotherapy are precise cancer treatment strategies aimed at minimizing systemic side effects. However, cancer metastasis remains the primary cause of mortality among cancer patients in clinical settings, and localized cancer treatments have limited efficacy against metastatic cancer. Therefore, researchers are exploring strategies that combine localized therapy with immunotherapy to activate robust anti-tumor immune responses, thereby eradicating metastatic cancer. Biomaterials, as novel materials, exhibit great potential in biomedical applications and have achieved great progress in clinic translation. This review introduces biomaterials and their applications in research focused on enhancing localized cancer treatment activated anti-tumor immunity. Additionally, the current challenges and future directions of biomaterials are also discussed, providing insights and references for related research.

Mechanical investigation of a Tandem embolization-visualization system for minimally invasive procedures

Transcatheter arterial embolization is a minimally invasive intervention process in which the blood supply to a tumor or an abnormal area of tissue is blocked. One of the most commonly used embolic agents in clinics is microsphere (MS). In order to understand the flow behavior of microspheres in arteries, it is essential to study their mechanical properties systematically. In this work, calcium-alginate MSs with varying calcium concentrations were synthesized using a coaxial airflow method. Indocyanine green (ICG) was added as a fluorescent dye. The effect of ICG concentration change on microspheres was investigated by studying morphology, imageability, rheology, and swelling behavior. Then the effect of calcium chloride concentration change on microspheres was studied by conducting rheological tests, atomic force microscopy tests, hemolysis assay, and thrombogenicity assay. Results showed that microspheres with higher ICG concentrations have longer lasting fluorescence and lower storage modulus (G'). Higher concentrations of calcium chloride led to higher G', while the local Young's modulus obtained by AFM test was not significantly affected. The MSs with and without ICG showed good hemocompatibility and thrombogenicity.

Breaking barriers in cancer management: The promising role of microsphere conjugates in cancer diagnosis and therapy

Cancer is a significant worldwide health concern, and there is a demand for ongoing breakthroughs in treatment techniques. Microspheres are among the most studied drug delivery platforms for delivering cargo to a specified location over an extended period of time. They are biocompatible, biodegradable, and capable of surface modifications. Microspheres and their conjugates have emerged as potential cancer therapeutic options throughout the years. This review provides an in-depth look at the current advancements and applications of microspheres and their conjugates in cancer treatment. The review encompasses a wide array of conjugates, ranging from polymers such as ethyl cellulose and Eudragit to stimuli-responsive polymers, proteins, peptides, polysaccharides such as HA and chitosan, inorganic metals, aptamers, quantum dots (QDs), biomimetic conjugates, and radio conjugates designed for radioembolization. Conjugated microspheres precisely deliver chemotherapeutics to the intended target while achieving controlled drug release to prevent side effects. It offers a means of integrating several distinct therapeutic modalities (chemotherapy, photothermal therapy, photodynamic therapy, radiotherapy, immunotherapy, etc.) to provide synergistic effects during cancer treatment. This review offers insights into the prospects and evolving role of microspheres and their conjugates in the dynamic landscape of cancer therapy. This review provides a comprehensive resource for researchers and clinicians working towards advancements in cancer treatment through innovative applications in therapy and translational research.

Intravascular Casting Radiopaque Hydrogel Systems for Transarterial Chemo/Cascade Catalytic/Embolization Therapy of Hepatocellular Carcinoma

This paper introduces catheter-directed intravascular casting hydrogels for transarterial chemo/starvation/chemodynamic embolization (TACSCE) therapy of hepatocellular carcinoma (HCC). Comprising Mn ion-crosslinked hyaluronic acid-dopamine (HD) with glucose oxidase (for glucose decomposition to H2O2 in starvation therapy), doxorubicin (for chemotherapy), and iopamidol (for X-ray imaging), these hydrogels are fabricated for transarterial embolization therapy guided by X-ray fluoroscopy. Mn4+ (from MnO2) demonstrates strong coordination with the catechol group of HD, providing hypoxia relief through O2 generation and cellular glutathione (GSH) consumption, compared to the OH radical generation potential of Mn2+. The gelation time-controlled, catheter-injectable, and rheologically tuned multitherapeutic/embolic gel system effectively reaches distal arterioles, ensuring complete intravascular casting with fewer complications related to organic solvents. Glucose deprivation, cascade reactive oxygen species (ROS) generation, GSH depletion, and sustained release profiles of multiple drug cargos from the hydrogel system are also achieved. The combined chemo/starvation/chemodynamic efficacies of these designed hydrogel systems are confirmed in HCC cell cultures and HCC-bearing animal models. The developed radiopaque/injectable/embolic/sol-to-gel transformable systems for TACSCE therapy may offer enhanced therapeutic efficacies compared to typical transarterial embolization and transarterial chemoembolization procedures for HCC.

Emulsion-Based Multi-Phase Integrated Microbeads with Inner Multi-Interface Structure Enable Dual-Modal Imaging for Precision Endovascular Embolization

Microsphere-based embolic agents have gained prominence in transarterial embolization (TAE) treatment, a critical minimally invasive therapy widely applied for a variety of diseases such as hypervascular tumors and acute bleeding. However, the development of microspheres with long-term, real-time, and repeated X-ray imaging as well as ultrasound imaging remains challenging. In this study, emulsion-based dual-modal imaging microbeads with a unique internal multi-interface structure is developed for TAE treatment. The embolic microbeads are fabricated from a solidified oil-in-water (O/W) emulsion composed of crosslinked CaAlg-based aqueous matrix and dispersed radiopaque iodinated oil (IO) droplets through a droplet-based microfluidic fabrication method. The CaAlg-IO microbeads exhibit superior X-ray imaging visibility due to the incorporation of exceptionally high iodine level up to 221 mgI mL-1, excellent ultrasound imaging capability attributed to the multi-interface structure of the O/W emulsion, great microcatheter deliverability thanks to their appropriate biomechanical properties and optimal microbead density, and extended drug release behavior owing to the biodegradation nature of the embolics. Such an embolic agent presents a promising emulsion-based platform to utilize multi-phased structures for improving endovascular embolization performance and assessment capabilities.

Advancements in hydrogel-based embolic agents: Categorized by therapeutic mechanisms

BACKGROUND

Transcatheter arterial embolization (TAE) is a crucial technique in interventional radiology. Hydrogel-based embolic agents show promise due to their phase transition and drug-loading capabilities. However, existing categorizations of these agents are confusing.

AIMS

This review tackles the challenge of categorizing hydrogel-based embolic agents based on their therapeutic mechanisms, including transportation, accumulation, interaction, and elimination. It also addresses current challenges and controversies in the field while highlighting future directions for hydrogel-based embolicagents.

MATERIALS AND METHODS

We conducted a systematic review of papers published in PUBMED from 2004 to 2024, focusing primarily on preclinical trials.

RESULTS

Various kinds of hydrogel embolic agents were introduced according to their therapeutic mechanisms.

DISCUSSION

Most hydrogel embolic agents were specifically designed for effective accumulation and interaction. Recent advancement highlight the potential of multifunctional hydrogel embolic agents.

CONCLUSION

This new categorizations provided valuable insights into hydrogel embolic agents, potentially guiding material scientists and interventional radiologists in the development of novel hydrogel embolic agents in transarterial embolization.

Intra-arterial locoregional therapies for intrahepatic cholangiocarcinoma

INTRODUCTION

Intrahepatic cholangiocarcinoma (ICC) is the 2nd most common primary liver malignancy. For nonsurgical candidates, the primary treatment option is systemic chemotherapy, which can be combined with locoregional therapies to enhance local control. Common intra-arterial locoregional therapies include transarterial hepatic embolization, conventional transarterial chemoembolization, drug-eluting bead transarterial chemoembolization, transarterial radioembolization with Yttrium-90 microspheres, and hepatic artery infusion. This article aims to review the latest literature on intra-arterial locoregional therapies for treating ICC.

AREAS COVERED

A literature search was conducted on PubMed using keywords: intrahepatic cholangiocarcinoma, intra-arterial locoregional therapy, embolization, chemoembolization, radioembolization, hepatic artery infusion, and immunotherapy. Articles from 2008 to 2024 were reviewed. Survival data from retrospective and prospective studies, meta-analyses, and clinical trials were evaluated.

EXPERT OPINION

Although no level I evidence supports the superiority of any specific intra-arterial therapy, there has been a shift toward favoring radioembolization. In our expert opinion, radioembolization may offer superior outcomes when performed by skilled operators with meticulous planning and personalized dosimetry, particularly for radiation segmentectomy or treating lobar/bilobar disease in appropriate candidates.

Immobilized Drugs on Dual-Mode Imaging Ag2S/BaSO4/PVA Embolic Microspheres for Precise Localization, Rapid Embolization, and Local Antitumor Therapy

Transcatheter arterial embolization (TAE) in interventional therapy and tumor embolism therapy plays a significant role. The choice of embolic materials that have good biocompatibility is an essential component of TAE. For this study, we produced a multifunctional PVA embolization material that can simultaneously encapsulate Ag2S quantum dots (Ag2S QDs) and BaSO4 nanoparticles (BaSO4 NPs), exhibiting excellent second near-infrared window (NIR-II) fluorescence imaging and X-ray imaging, breaking through the limitations of traditional embolic microsphere X-ray imaging. To improve the therapeutic effectiveness against tumors, we doped the doxorubicin (DOX) antitumor drug into microspheres and combined it with a clotting peptide (RADA16-I) on the surface of microspheres. Thus, it not only embolizes rapidly during hemostasis but also continues to release and accelerate tumor necrosis. In addition, Ag2S/BaSO4/PVA microspheres (Ag2S/BaSO4/PVA Ms) exhibited good blood compatibility and biocompatibility, and the results of embolization experiments on renal arteries in rabbits revealed good embolic effects and bimodal imaging stability. Therefore, they could serve as a promising medication delivery embolic system and an efficient biomaterial for arterial embolization. Our research work achieves the applicability of NIR-II and X-ray dual-mode images for clinical embolization in biomedical imaging.

Designing polysaccharide materials for tissue repair and regeneration

Tissue repair and regeneration are critical processes for maintaining the integrity and function of various organs and tissues. Recently, polysaccharide materials and protein materials have garnered interest for use in tissue repair strategies. However, polysaccharides are more stable and unaffected by temperature and pH changes compared to proteins, and some polysaccharides can provide stronger mechanical support, which is particularly important for constructing tissue-engineered scaffolds and wound dressings. This Review provides an in-depth overview of the origins of polysaccharides, the advantages of polysaccharide materials, and processing and design strategies. In addition, the potential of polysaccharide materials for the restoration of tissues such as skin, heart, and nerves is highlighted. Finally, we discuss in depth the challenges that polysaccharide materials still face in tissue repair, such as the stability of the material, regulating mechanical characteristics and deterioration rates under different conditions. To achieve more effective tissue repair and regeneration, future research must focus on further improving the characteristics and functionalities of polysaccharide materials.

Functional hydrogels for hepatocellular carcinoma: therapy, imaging, and in vitro model

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide and is characterized by high rates of morbidity and mortality, posing a serious threat to human health. Interventional embolization therapy is the main treatment against middle- and late-stage liver cancer, but its efficacy is limited by the performance of embolism, hence the new embolic materials have provided hope to the inoperable patients. Especially, hydrogel materials with high embolization strength, appropriate viscosity, reliable security and multifunctionality are widely used as embolic materials, and can improve the efficacy of interventional therapy. In this review, we have described the status of research on hydrogels and challenges in the field of HCC therapy. First, various preparation methods of hydrogels through different cross-linking methods are introduced, then the functions of hydrogels related to HCC are summarized, including different HCC therapies, various imaging techniques, in vitro 3D models, and the shortcomings and prospects of the proposed applications are discussed in relation to HCC. We hope that this review is informative for readers interested in multifunctional hydrogels and will help researchers develop more novel embolic materials for interventional therapy of HCC.

Monodisperse Polyaspartic Acid Derivative Microspheres for Potential Tumor Embolization Therapy

Polyaspartic acid derivatives are a well-known kind of polypeptide with good biocompatibility and biodegradability, and thus have been widely used as biomedical materials, including drug-loaded nano-scale micelles or macroscopic hydrogels. In this work, for the first time, monodisperse polyaspartic acid derivative microspheres with diameter ranging from 120 to 350 µm for potential tumor embolization therapy are successfully prepared by single emulsion droplet microfluidic technique. The obtained microsphere shows fast cationic anticancer drug doxorubicin hydrochloride loading kinetics with high loading capacity, which is much better than those of the commercial ones. Additionally, drug release behaviors of the drug-loaded microspheres with different diameters in different media are also studied and discussed in detail. These results provide some new insights for the preparation and potential application of polyaspartic acid derivative-based monodisperse microspheres, especially for their potential application as embolic agent.

Fabrication of polymeric microspheres for biomedical applications

Polymeric microspheres (PMs) have attracted great attention in the field of biomedicine in the last several decades due to their small particle size, special functionalities shown on the surface and high surface-to-volume ratio. However, how to fabricate PMs which can meet the clinical needs and transform laboratory achievements to industrial scale-up still remains a challenge. Therefore, advanced fabrication technologies are pursued. In this review, we summarize the technologies used to fabricate PMs, including emulsion-based methods, microfluidics, spray drying, coacervation, supercritical fluid and superhydrophobic surface-mediated method and their advantages and disadvantages. We also review the different structures, properties and functions of the PMs and their applications in the fields of drug delivery, cell encapsulation and expansion, scaffolds in tissue engineering, transcatheter arterial embolization and artificial cells. Moreover, we discuss existing challenges and future perspectives for advancing fabrication technologies and biomedical applications of PMs.

Polymer Microspheres and Their Application in Cancer Diagnosis and Treatment

Cancer is a significant global public health issue with increasing morbidity and mortality rates. To address this challenge, novel drug carriers such as nano-materials, liposomes, hydrogels, fibers, and microspheres have been extensively researched and utilized in oncology. Among them, polymer microspheres are gaining popularity due to their ease of preparation, excellent performance, biocompatibility, and drug-release capabilities. This paper categorizes commonly used materials for polymer microsphere preparation, summarizes various preparation methods (emulsification, phase separation, spray drying, electrospray, microfluidics, and membrane emulsification), and reviews the applications of polymer microspheres in cancer diagnosis, therapy, and postoperative care. The current status and future development directions of polymer microspheres in cancer treatment are analyzed, highlighting their importance and potential for improving patient outcomes.

Engineering polyvinyl alcohol microspheres with capability for use in photothermal/chemodynamic therapy for enhanced transarterial chemoembolization

Transarterial chemoembolization (TACE) is widely recognized as a non-surgical treatment approach for advanced liver cancer, combining chemotherapy with the blockage of blood vessels supplying the tumor. To enhance the efficacy of TACE and address chemotherapy resistance, there is growing interest in the development of multifunctional embolic microspheres. In this study, multifunctional PVA microspheres, which encapsulate MIT as a chemotherapeutic drug, PPY as a photothermal agent, and Fe3O4 as a chemodynamic therapy agent, were prepared successfully. The results demonstrated that the developed multifunctional PVA microspheres not only exhibit favorable drug release, photothermal therapy, and chemodynamic therapy performance, but also show a promising synergistic therapeutic effect both in vitro and in vivo. Consequently, the engineered multifunctional PVA microspheres hold tremendous promise for enhancing TACE effectiveness and have the potential to overcome limitations associated with traditional liver cancer treatments.

Recent advances in hepatocellular carcinoma-targeted nanoparticles

In the field of medicine, we often brave the unknown like interstellar explorers, especially when confronting the formidable opponent of hepatocellular carcinoma (HCC). The global burden of HCC remains significant, with suboptimal treatment outcomes necessitating the urgent development of novel drugs and treatments. While various treatments for liver cancer, such as immunotherapy and targeted therapy, have emerged in recent years, improving their transport and therapeutic efficiency, controlling their targeting and release, and mitigating their adverse effects remains challenging. However, just as we grope through the darkness, a glimmer of light emerges-nanotechnology. Recently, nanotechnology has attracted attention because it can increase the local drug concentration in tumors, reduce systemic toxicity, and has the potential to enhance the effectiveness of precision therapy for HCC. However, there are also some challenges hindering the clinical translation of drug-loaded nanoparticles (NPs). Just as interstellar explorers must overcome interstellar dust, we too must overcome various obstacles. In future researches, the design and development of nanodelivery systems for novel drugs treating HCC should be the first attention. Moreover, researchers should focus on the active targeting design of various NPs. The combination of the interventional therapies and drug-loaded NPs will greatly advance the process of precision HCC therapy.

Current research status and development prospects of embolic microspheres containing biological macromolecules and others

Transcatheter arterial embolization (TACE) has been used in the treatment of malignant tumors, sudden hemorrhage, uterine fibroids, and other diseases, and with advances in imaging techniques and devices, materials science, and drug release technology, more and more embolic agents that are drug-carrying, self-imaging, or have multiple functions are being developed. Microspheres provide safer and more effective therapeutic results as embolic agents, with their unique spherical appearance and good embolic properties. Embolic microspheres are the key to arterial embolization, blocking blood flow and nutrient supply to the tumor target. This review summarizes some of the currently published embolic microspheres, classifies embolic microspheres according to matrix, and summarizes the characteristics of the microsphere materials, the current status of research, directions, and the value of existing and potential applications. It provides a direction to promote the development of embolic microspheres towards multifunctionalization, and provides a reference to promote the research and application of embolic microspheres in the treatment of tumors.

Novel therapeutic approaches for the management of hepatitis infections

Hepatitis B virus (HBV) & hepatitis C virus (HCV) infection is a substantial reason for morbidity and mortality around the world. Chronic hepatitis B (CHB) infection is connected with an enhanced risk of liver cirrhosis, liver decompensation and hepatocellular carcinoma (HCC). Conventional therapy do face certain challenges, for example, poor tolerability and the growth of active resistance. Thus, novel treatment procedures are essential to accomplish the initiation of strong and stable antiviral immune reactions of the individuals. This review explores the current nanotechnology-based carriers for drug and vaccine delivery to treat HBV and HCV.

Microparticles and multi-unit systems for advanced drug delivery

Microparticles have unique benefits in the formulation of multiparticulate and multi-unit type pharmaceutical dosage forms allowing improved drug safety and efficacy with favorable pharmacokinetics and patient centricity. On the other hand, the above advantages are served by high and well reproducible quality attributes of the medicinal product where even flexible design and controlled processability offer success as well as possible longer product life-cycle for the manufacturers. Moreover, the specific demands of patients can be taken into account, including simplified dosing regimens, flexible dosage, drug combinations, palatability, and ease of swallowing. In the more than 70 years since the first modified-release formulation appeared on the market, many new formulations have been marketed and many publications have appeared in the literature. More unique and newer pharmaceutical technologies and excipients have become available for producing tailor-made particles with micrometer dimensions and beyond. All these have contributed to the fact that the sub-units (e.g. minitablets, pellets, microspheres) that make up a multiparticulate system can vary widely in composition and properties. Some units have mucoadhesive properties and others can float to contribute to a suitable release profile that can be designed for the multiparticulate formula as a whole. Nowadays, there are some available formulations on the market, which are able to release the active substance even for several months (3 or 6 months depending on the type of treatment). In this review, the latest developments in technologies that have been used for a long time are presented, as well as innovative solutions such as the applicability of 3D printing to produce subunits of multiparticulate systems. Furthermore, the diversity of multiparticulate systems, different routes of administration are also presented, touching the ones which are capable of carrying the active substance as well as the relevant, commercially available multiparticle-based medical devices. The versatility in size from 1 µm and multiplicity of formulation technologies promise a solid foundation for the future applications of dosage form design and development.

The Use of Microspheres for Cancer Embolization Therapy: Recent Advancements and Prospective

Embolization therapy involving biomaterials has improved the therapeutic strategy for most liver cancer treatments. Developing biomaterials as embolic agents has significantly improved patients' survival rates. Various embolic agents are present in liquid agents, foam, particulates, and particles. Some of the most applied embolic agents are microparticles, such as microspheres (3D micrometer-sized spherical particles). Microspheres with added functionalities are currently being developed for effective therapeutic embolization. Their excellent properties of high surface area and capacity for being loaded with radionuclides and alternate active or therapeutic agents provide an additional advantage to overcome limitations from traditional cancer treatments. Microspheres (non-radioactive and radioactive) have been widely used and explored for localized cancer treatment. Non-radioactive microspheres exhibit improved clinical performance as drug delivery vehicles in chemotherapy due to their controlled and sustained drug release to the target site. They offer better flow properties and are beneficial for the ease of delivery via injection procedures. In addition, radioactive microspheres have also been exploited for use as an embolic platform in internal radiotherapy as an alternative to cancer treatment. This short review summarizes the progressive development of non-radioactive and radioactive embolic microspheres, emphasizing material characteristics. The use of embolic microspheres for various modalities of therapeutic arterial embolization and their impact on therapeutic performance are also discussed.

Luteolin, a flavone ingredient: Anticancer mechanisms, combined medication strategy, pharmacokinetics, clinical trials, and pharmaceutical researches

Current pharmaceutical research is energetically excavating the pharmacotherapeutic role of herb-derived ingredients in multiple malignancies' targeting. Luteolin is one of the major phytochemical components that exist in various traditional Chinese medicine or medical herbs. Mounting evidence reveals that this phytoconstituent endows prominent therapeutic actions on diverse malignancies, with the underlying mechanisms, combined medication strategy, and pharmacokinetics elusive. Additionally, the clinical trial and pharmaceutical investigation of luteolin remain to be systematically delineated. The present review aimed to comprehensively summarize the updated information with regard to the anticancer mechanism, combined medication strategies, pharmacokinetics, clinical trials, and pharmaceutical researches of luteolin. The survey corroborates that luteolin executes multiple anticancer effects mainly by dampening proliferation and invasion, spurring apoptosis, intercepting cell cycle, regulating autophagy and immune, inhibiting inflammatory response, inducing ferroptosis, and pyroptosis, as well as epigenetic modification, and so on. Luteolin can be applied in combination with numerous clinical anticarcinogens and natural ingredients to synergistically enhance the therapeutic efficacy of malignancies while reducing adverse reactions. For pharmacokinetics, luteolin has an unfavorable oral bioavailability, it mainly persists in plasma as glucuronides and sulfate-conjugates after being metabolized, and is regarded as potent inhibitors of OATP1B1 and OATP2B1, which may be messed with the pharmacokinetic interactions of miscellaneous bioactive substances in vivo. Besides, pharmaceutical innovation of luteolin with leading-edge drug delivery systems such as host-guest complexes, nanoparticles, liposomes, nanoemulsion, microspheres, and hydrogels are beneficial to the exploitation of luteolin-based products. Moreover, some registered clinical trials on luteolin are being carried out, yet clinical research on anticancer effects should be continuously promoted.

Peptide fractions from Sacha inchi induced apoptosis in HepG2 cells via P53 activation and a mitochondria-mediated pathway

BACKGROUND

Sacha inchi is known for its high protein content and medicinal properties. Bioactive peptides have been reported to have therapeutic potential in various human diseases. However, there is a lack of research evaluating the pharmacological value of peptides derived from Sacha inchi. Therefore, this study aimed to investigate the anti-hepatoma effect of Sacha inchi peptides (SPs) and their underlying mechanism.

RESULTS

The study found that treatment with SPs significantly reduced the proliferation of HepG2 cells by inducing apoptosis and arresting the cell cycle at the G0/G1 phase. SPs also induced HepG2 cell apoptosis by increasing the levels of proteins such as Bax, Caspase-3 and P53. The study identified nine novel peptides in SPs, of which LLEPDVR, ALVEKAKAS and TGDGSLRPY exhibited higher cell proliferative inhibition rates compared to other peptides.

CONCLUSION

The findings of this study suggest that Sacha inchi peptides have potential pharmacological effects in the treatment of liver cancer. SPs effectively suppress the cell cycle and facilitate cell apoptosis, indicating their anti-hepatoma effect. The novel peptides identified in SPs may have therapeutic value for liver cancer treatment. © 2023 Society of Chemical Industry.

Polymer composite microspheres loading 177Lu radionuclide for interventional radioembolization therapy and real-time SPECT imaging of hepatic cancer

BACKGROUND

Transarterial radioembolization (TARE) with 90Y-labeled glass and resin microspheres is one of the primary treatment strategies for advanced-stage primary and metastatic hepatocellular carcinoma (HCC). However, difficulties of real-time monitoring post administration and embolic hypoxia influence treatment prognosis. In this study, we developed a new biodegradable polymer microsphere that can simultaneously load 177Lu and MgO nanoparticle, and evaluated the TARE therapeutic efficacy and biosafety of 177Lu-PDA-CS-MgO microspheres for HCC treatment.

METHODS

Chitosan microspheres were synthesized through emulsification crosslink reaction and then conducted surface modification with polydopamine (PDA). The 177Lu and nano MgO were conjugated to microspheres using active chemical groups of PDA. The characteristics of radionuclide loading efficiency, biodegradability, blood compatibility, and anti-tumor effectwere evaluated both in vitro and in vivo. SPECT/CT imaging was performed to monitor bio-distribution and bio-stability of 177Lu-PDA-CS-MgO after TARE treatment. The survival duration of each rat was monitored. HE analysis, TUNEL analysis, immunohistochemical analysis, and western blot analysis were conducted to explore the anti-tumor effect and mechanism of composited microspheres. Body weight, liver function, blood routine examination were monitored at different time points to evaluate the bio-safety of microspheres.

RESULTS

The composite 177Lu-PDA-CS-MgO microsphere indicated satisfactory degradability, biocompatibility, radionuclide loading efficiency and radiochemical stability in vitro. Cellular evaluation showed that 177Lu-PDA-CS-MgO had significant anti-tumor effect and blocked tumor cell cycles in S phase. Surgical TARE treatment with 177Lu-PDA-CS-MgO significantly prolonged the medial survival time from 49 d to 105 d, and effectively inhibited primary tumor growth and small metastases spreading. Moreover, these microspheres indicated ideal in vivo stability and allowed real-time SPECT/CT monitoring for up to 8 weeks. Immunostaining and immunoblotting results also confirmed that 177Lu-PDA-CS-MgO had potential in suppressing tumor invasion and angiogenesis, and improved embolic hypoxia in HCC tissues. Further evaluations of body weight, blood test, and pathological analysis indicated good biosafety of 177Lu-PDA-CS-MgO microspheres in vivo.

CONCLUSION

Our study demonstrated that 177Lu-PDA-CS-MgO microsphere hold great potential as interventional brachytherapy candidate for HCC therapy. Polymer composite microspheres loading 177Lu radionuclide and MgO nanoparticles for interventional radioembolization therapy and real-time SPECT imaging of hepatic cancer.

Efferocytosis Nanoinhibitors to Promote Secondary Necrosis and Potentiate the Immunogenicity of Conventional Cancer Therapies for Improved Therapeutic Benefits

Efferocytosis of apoptotic cancer cells by tumor-associated macrophages or other phagocytes is reported to promote tumor immunosuppression by preventing them from secondary necrosis, which would lead to the release of intracellular components and thus enhanced immunogenicity. Therefore, current apoptosis-inducing cancer treatments (e.g., chemotherapy and radiotherapy) are less satisfactory in eliciting antitumor immunity. Herein, a nanoparticulate inhibitor of efferocytosis is prepared by encapsulating BMS777607, a hydrophobic inhibitor of receptors in macrophages responsible for phosphatidylserine-dependent efferocytosis, with biocompatible poly(lactic-co-glycolic acid) and its amphiphilic derivatives. The yielded nano-BMS can inhibit the efferocytosis of apoptotic cancer cells, thus redirecting them to immunogenic secondary necrosis. As a result, intratumorally injected nano-BMS is capable of activating both innate and adaptive antitumor immunity to achieve greatly improved therapeutic responses, when synergized with nonimmunogenic chemotherapy by cisplatin, immunogenic chemotherapy by oxaliplatin, or radiotherapy by external beams. Moreover, we further demonstrate that the inhalation of nano-BMS could significantly promote the efficacy of cisplatin chemotherapy to suppress tumor lung metastases. Therefore, this study highlights a general strategy to potentiate the immunogenicity of different cancer treatments by suppressing efferocytosis-propelled tumor immunosuppression, showing tremendous clinical potential in rescuing existing cancer therapies for more effective treatment.

Janus particle-engineered structural lipiodol droplets for arterial embolization

Embolization (utilizing embolic materials to block blood vessels) has been considered one of the most promising strategies for clinical disease treatments. However, the existing embolic materials have poor embolization effectiveness, posing a great challenge to highly efficient embolization. In this study, we construct Janus particle-engineered structural lipiodol droplets by programming the self-assembly of Janus particles at the lipiodol-water interface. As a result, we achieve highly efficient renal embolization in rabbits. The obtained structural lipiodol droplets exhibit excellent mechanical stability and viscoelasticity, enabling them to closely pack together to efficiently embolize the feeding artery. They also feature good viscoelastic deformation capacities and can travel distally to embolize finer vasculatures down to 40 μm. After 14 days post-embolization, the Janus particle-engineered structural lipiodol droplets achieve efficient embolization without evidence of recanalization or non-target embolization, exhibiting embolization effectiveness superior to the clinical lipiodol-based emulsion. Our strategy provides an alternative approach to large-scale fabricate embolic materials for highly efficient embolization and exhibits good potential for clinical applications.

Genicular Artery Embolization for Knee Osteoarthritis: A Comprehensive Review

» Genicular artery embolization (GAE) is a promising treatment option for patients with knee osteoarthritis who are unresponsive to nonsurgical treatments and not yet candidates for surgery.» Current evidence supports the effectiveness of GAE in reducing pain and synovitis, with few reported major adverse events.» The cost-effectiveness and long-term results of GAE compared with other treatment options require further investigation.» Limitations of existing studies include small sample sizes, single-center trials, and lack of comparison between embolic agents and other treatments.» Future research should focus on larger, multicenter trials with longer follow-up periods and head-to-head comparisons with alternative treatment modalities to establish the role of GAE in the management of knee osteoarthritis.

Microfluidic fabrication of X-ray-visible sodium hyaluronate microspheres for embolization

Catheter embolization is a minimally invasive technique that relies on embolic agents and is now widely used to treat various high-prevalence medical diseases. Embolic agents usually need to be combined with exogenous contrasts to visualize the embolotherapy process. However, the exogenous contrasts are quite simply washed away by blood flow, making it impossible to monitor the embolized location. To solve this problem, a series of sodium hyaluronate (SH) loaded with bismuth sulfide (Bi₂S₃) nanorods (NRs) microspheres (Bi₂S₃@SH) were prepared in this study by using 1,4-butaneglycol diglycidyl ether (BDDE) as a crosslinker through single-step microfluidics. Bi₂S₃@SH-1 microspheres showed the best performance among other prepared microspheres. The fabricated microspheres had uniform size and good dispersibility. Furthermore, the introduction of Bi₂S₃ NRs synthesized by a hydrothermal method as Computed Tomography (CT) contrast agents improved the mechanical properties of Bi₂S₃@SH-1 microspheres and endowed the microspheres with excellent X-ray impermeability. The blood compatibility and cytotoxicity test showed that the Bi₂S₃@SH-1 microspheres had good biocompatibility. In particular, the in vitro simulated embolization experiment results indicate that the Bi₂S₃@SH-1 microspheres had excellent embolization effect, especially for the small-sized blood vessels of 500-300 and 300 μm. The results showed the prepared Bi₂S₃@SH-1 microspheres have good biocompatibility and mechanical properties, as well as certain X-ray visibility and excellent embolization effects. We believe that the design and combination of this material has good guiding significance in the field of embolotherapy.

In Vitro Biodegradation, Drug Absorption, and Physical Properties of Gelatin-Fucoidan Microspheres Made of Subcritical-Water-Modified Fish Gelatin

This study aimed to prepare gelatin-fucoidan microspheres with enhanced doxorubicin binding efficiency and controllable biodegradation using fish gelatin combined with low molecular weight (LMW) gelatin and fucoidan at fixed ratios. The MW of gelatin was modified by subcritical water (SW), which is known as a safe solvent, at 120 °C, 140 °C, and 160 °C. In addition, gelatin-fucoidan microspheres were prepared using a solvent exchange technique. Our findings revealed that particle size decreased, the surface was rougher, the swelling ratio increased, and particle shape was irregular in microspheres composed of SW-modified gelatin. Doxorubicin binding efficiency was improved by fucoidan and SW-modified gelatin at 120 °C but not at 140 °C and 160 °C. Interestingly, an increase in in vitro enzymatic degradation was observed in the microspheres consisting of SW-modified fish gelatin, although the cross-linking degree between them was not significantly different. This is because LMW gelatin could form more cross-linked bonds, which might be weaker than the intramolecular bonds of gelatin molecules. Gelatin-fucoidan microspheres consisting of SW-modified fish gelatin with controlled biodegradation rates could be a candidate for a short-term transient embolization agent. In addition, SW would be a promising method to modify the MW of gelatin for medical applications.

Polydopamine-Coated Radiolabeled Microspheres for Combinatorial Radioembolization and Photothermal Cancer Therapy

Transarterial radioembolization (TARE) is a local radionuclide therapy and is successfully used in hepatocellular carcinoma (HCC) treatment. Radioactive microspheres have been widely studied for TARE. Preparation of ideal radioactive microspheres is significant for clinical research and patient treatment. In this study, we have designed a novel multifunctional microsphere, i.e., polydopamine (PDA)-coated ¹⁷⁷Lu-radiolabeled silica microspheres (MS) denoted as ¹⁷⁷Lu-MS@PDA, which can be used for TARE and photothermal therapy (PTT). The radiostability of ¹⁷⁷Lu-MS@PDA was significantly improved by coating ¹⁷⁷Lu-MS with PDA. In addition, the coating of PDA makes microspheres have excellent photothermal performance. MicroSPECT/CT images showed that ¹⁷⁷Lu-MS@PDA was accurately embolized and remained in the tumor during the observation time. At the time, it also showed that ¹⁷⁷Lu-MS@PDA was very stable in vivo. Furthermore, the anti-tumor results demonstrated that TARE combined with PTT of ¹⁷⁷Lu-MS@PDA can significantly inhibit tumor growth without obvious side effects. ¹⁷⁷Lu-MS@PDA holds great potential as a promising radioactive microsphere for HCC.

Microspheres as a Carrier System for Therapeutic Embolization Procedures: Achievements and Advances

The targeted delivery of anti-cancer drugs and isotopes is one of the most pursued goals in anti-cancer therapy. One of the prime examples of such an application is the intra-arterial injection of microspheres containing cytostatic drugs or radioisotopes during hepatic embolization procedures. Therapy based on the application of microspheres revolves around vascular occlusion, complemented with local therapy in the form of trans-arterial chemoembolization (TACE) or radioembolization (TARE). The broadest implementation of these embolization strategies currently lies within the treatment of untreatable hepatocellular cancer (HCC) and metastatic colorectal cancer. This review aims to describe the state-of-the-art TACE and TARE technologies investigated in the clinical setting for HCC and addresses current trials and new developments. In addition, chemical properties and advancements in microsphere carrier systems are evaluated, and possible improvements in embolization therapy based on the modification of and functionalization with therapeutical loads are explored.

Material characterization of GPX®: A versatile in situ solidifying embolic platform technology

Endovascular embolization is a minimally invasive procedure during which blood flow to targeted tissues is selectively occluded. The list of clinical indications for embolization continues to expand. Liquid embolic agents are injectable compositions that transition into a solid or semi-solid form when introduced into blood vessels. The mechanism that triggers the liquid-to-solid transition is a key distinguishing feature of liquid embolic agents. GPX is a waterborne liquid embolic agent comprising oppositely charged polyelectrolytes: polyguanidinum and inorganic polyphoshate. In situ solidification is driven by electrostatic condensation of the polyelectrolytes, triggered by ionic strength differentials. We report in vitro characterization of the material properties of GPX, it is in vivo effectiveness in acute animal studies, and its potential for chemoembolization. The viscosity of GPX can be varied over a wide range by adjusting the polyguanidinium MW and/or concentration. Formulation of GPX with either tantalum microparticles (30 wt%) or iodinated radiocontrast agents (300 mgI ml^-1) did not significantly change the flow behavior of GPX; the viscosity was independent of shear rate and remained within a clinically practical range (80-160 cP). Formulation of GPX with doxorubicin substantially increased viscosity at low shear rates and resulted in a power law dependence on shear rate. High contrast and effective vascular occlusion were demonstrated in both swine kidneys and rete mirabile. Contrast from iodinated compounds was temporary, dissipating within hours. The doxorubicin in vitro release profile was linear over 90 days. The results demonstrate that GPX is a versatile liquid embolic platform that can be formulated with a wide range of viscosities injectable at clinically practical flow rates, with either transient or permanent contrast, and that can provide prolonged zero-order delivery of doxorubicin to embolized tissues.

Review targeted drug delivery systems for norcantharidin in cancer therapy

Norcantharidin (NCTD) is a demethylated derivative of cantharidin (CTD), the main anticancer active ingredient isolated from traditional Chinese medicine Mylabris. NCTD has been approved by the State Food and Drug Administration for the treatment of various solid tumors, especially liver cancer. Although NCTD greatly reduces the toxicity of CTD, there is still a certain degree of urinary toxicity and organ toxicity, and the poor solubility, short half-life, fast metabolism, as well as high venous irritation and weak tumor targeting ability limit its widespread application in the clinic. To reduce its toxicity and improve its efficacy, design of targeted drug delivery systems based on biomaterials and nanomaterials is one of the most feasible strategies. Therefore, this review focused on the studies of targeted drug delivery systems combined with NCTD in recent years, including passive and active targeted drug delivery systems, and physicochemical targeted drug delivery systems for improving drug bioavailability and enhancing its efficacy, as well as increasing drug targeting ability and reducing its adverse effects.

Graphical Abstract

Multifunctional microrobot with real-time visualization and magnetic resonance imaging for chemoembolization therapy of liver cancer

Microrobots that can be precisely guided to target lesions have been studied for in vivo medical applications. However, existing microrobots have challenges in vivo such as biocompatibility, biodegradability, actuation module, and intra- and postoperative imaging. This study reports microrobots visualized with real-time x-ray and magnetic resonance imaging (MRI) that can be magnetically guided to tumor feeding vessels for transcatheter liver chemoembolization in vivo. The microrobots, composed of a hydrogel-enveloped porous structure and magnetic nanoparticles, enable targeted delivery of therapeutic and imaging agents via magnetic guidance from the actuation module under real-time x-ray imaging. In addition, the microrobots can be tracked using MRI as postoperative imaging and then slowly degrade over time. The in vivo validation of microrobot system-mediated chemoembolization was demonstrated in a rat liver with a tumor model. The proposed microrobot provides an advanced medical robotic platform that can overcome the limitations of existing microrobots and current liver chemoembolization.

CT/MR detectable magnetic microspheres for self-regulating temperature hyperthermia and transcatheter arterial chemoembolization

The embolic microspheres containing magnetic nanoparticles and anti-tumor drugs have been proposed for transcatheter arterial chemoembolization (TACE). However, this technique still suffers the poor control of hyperthermia temperature and drug release behavior. Herein, the magnetic microspheres based on low Curie temperature superparamagnetic iron oxide nanoparticles are developed by emulsification cross-linking of gelatin, genipin, and sodium alginate. The magnetic microspheres can self-regulate the hyperthermia temperature at around 50°C, un-necessitating any temperature control facilities. The magnetic microspheres can load doxorubicin hydrochloride and the loaded drug can be released in a controllable way by using an alternating magnetic field. Cytocompatibility and hemolysis evaluations confirm the non-cytotoxicity and negligible hemolysis of magnetic microspheres. The embolization model on rabbit auricular artery demonstrates that the magnetic microspheres can occlude the targeted blood vessel and are visualized under CT/MR imaging. All these findings suggest that the prepared magnetic microspheres could be used as the embolic agent in TACE. STATEMENT OF SIGNIFICANCE: The existing magnetic embolic microspheres suffer the poor control of hyperthermia temperature and drug release behavior in TACE. In this work, we developed the magnetic embolic microspheres based on superparamagnetic iron oxide nanoparticles with a low Curie temperature. Upon the application of alternating magnetic field, the embolic microspheres can self-regulate the hyperthermia temperature at around 50°C and the drug loaded in the microspheres can be released in a somewhat controllable manner. The embolic microspheres are also detectable to both CT and MR. These characteristics enable the developed microspheres to simultaneously realize self-regulating temperature hyperthermia, on-demand drug release, embolism, and CT/MR imaging.