Radiopaque and uniform alginate microspheres loaded with tantalum nanoparticles for real-time imaging during transcatheter arterial embolization

Thrombin Immobilized Hemocompatible Radiopaque Polyurethane Microspheres for Topical Blood Coagulation

Over the past decade, there has been growing interest in developing microspheres for embolization procedures. However, the lack of noninvasive monitoring of the embolic agents and the occurrence of reflux phenomenon leading to unintentional occlusions has raised concerns regarding their compatibility/suitability for embolization therapy. Here we report the development of specialty microspheres having intrinsic radiopacity and surface functionality to tackle the existing complications that pave the way for more advanced solutions. To achieve the above goal, an iodinated monomer, termed "IBHV," capable of imparting radiopacity and functionality, was synthesized and used as a chain extender to make radiopaque polyurethane. Microspheres with a smooth surface and an average diameter of 474 ± 73 μm were fabricated from this polyurethane. The microspheres obtained were noncytotoxic, had a permissible hemolysis rate, and showed better traceability on x-ray imaging. Subsequent immobilization of thrombin onto microspheres improved their hemostatic effect. This study demonstrated that immobilization of thrombin would lead to microspheres with unique traits of radiopacity and hemostatic properties, which will undoubtedly enhance embolization efficiency.

Intelligent Generic High-Throughput Oscillatory Shear Technology Fabricates Programmable Microrobots for Real-Time Visual Guidance During Embolization

Microrobots for endovascular embolization face challenges in precise delivery within dynamic blood vessels. Here, an intelligent generic high-throughput oscillatory shear technology (iGHOST) is proposed to fabricate diversely programmable, multifunctional microrobots capable of real-time visual guidance for in vivo endovascular embolization. Leveraging machine learning (ML), key synthesis parameters affecting the success and sphericity of the microrobots are identified. Therefore, the ML-optimized iGHOST enables continuous production of uniform microrobots with programmable sizes (400-1000 µm) at an ultrahigh rate exceeding 240 mL h-1 by oscillatory segmenting fluid into droplets before ionic cross-linking, and without requiring purification. Particularly, the iGHOST-fabricated magnetically responsive lipiodol-calcium alginate (MagLiCA) microrobots are highly distinguishable under X-ray imaging, which allows for precise navigation in fluid flows of up to 4 mL min-1 and accurate embolization in liver and kidney blood vessels, thus addressing the current issues. Crucially, MagLiCA microrobots possess drug-loading capabilities, enabling simultaneous embolization and site-specific treatment. The iGHOST process is an intelligent, rapid, and green manufacturing method, which can produce size-controllable, multifunctional microrobots with the potential for precise drug delivery and treatment under real-time imaging across various medical applications.

Idarubicin-loaded degradable hydrogel for TACE therapy enhances anti-tumor immunity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common and deadly cancer, often diagnosed at advanced stages, limiting surgical options. Transcatheter arterial chemoembolization (TACE) is a primary treatment for inoperable and involves the use of drug-eluting microspheres to slowly release chemotherapy drugs. However, patient responses to TACE vary, with some experiencing tumor progression and recurrence. Traditional TACE uses agents like oil-based drug emulsions and polyvinyl alcohol particles, which can permanently block blood vessels and increase tumor hypoxia. Additionally, TACE can suppress the immune system by reducing immune cell numbers and function, contributing to poor treatment outcomes. New approaches, like TACE using degradable starch microspheres and hydrogel-based materials, offer the potential to create different tumor environments that could improve both safety and efficacy. In our research, we developed a composite hydrogel (IF@Gel) made of Poloxamer-407 gel and Fe3O4 nanoparticles, loaded with idarubicin, to use as an embolic material for TACE in a rat model of orthotopic HCC. We observed promising therapeutic effects and investigated the impact on the tumor immune microenvironment, focusing on the role of immunogenic cell death (ICD). The composite hydrogel demonstrated excellent potential as an embolic material for TACE, and IF@Gel-based TACE demonstrated significant efficacy in rat HCC. Furthermore, our findings highlight the potential synergistic effects of ICD with anti-PD-L1 therapy, providing new insights into HCC treatment strategies. This study aims to provide improved treatment options for HCC and to deepen our understanding of the mechanisms of TACE and tumor environment regulation.

Application of nanotechnology in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma is the predominant histologic variant of hepatic malignancy and has become a major challenge to global health. The increasing incidence and mortality of hepatocellular carcinoma has created an urgent need for effective prevention, diagnosis, and treatment strategies. This is despite the impressive results of multiple treatments in the clinic. However, the unique tumor immunosuppressive microenvironment of hepatocellular carcinoma increases the difficulty of treatment and immune tolerance. In recent years, the application of nanoparticles in the treatment of hepatocellular carcinoma has brought new hope for tumor patients. Nano agents target tumor-associated fibroblasts, regulatory T cells, myeloid suppressor cells, tumor-associated macrophages, tumor-associated neutrophils, and immature dendritic cells, reversed the immunosuppressive microenvironment of hepatocellular carcinoma. In addition, he purpose of this review is to summarize the advantages of nanotechnology in guiding surgical excision, local ablation, TACE, standard chemotherapy, and immunotherapy, application of nano-vaccines has also continuously enriched the treatment of liver cancer. This study aims to investigate the potential applications of nanotechnology in the management of hepatocellular carcinoma, with the ultimate goal of enhancing therapeutic outcomes and improving the prognosis for patients affected by this malignancy.

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.

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.

Biodegradable Microembolics with Nanografted Polyanions Enable High-Efficiency Drug Loading and Sustained Deep-Tumor Drug Penetration for Locoregional Chemoembolization Treatment

Transarterial chemoembolization (TACE), the mainstay treatment of unresectable primary liver cancer that primarily employs nondegradable drug-loaded embolic agents to achieve synergistic vascular embolization and locoregional chemotherapy effects, suffers from an inferior drug burst behavior lacking long-term drug release controllability that severely limits the TACE efficacy. Here we developed gelatin-based drug-eluting microembolics grafted with nanosized poly(acrylic acid) serving as a biodegradable ion-exchange platform that leverages a counterion condensation effect to achieve high-efficiency electrostatic drug loading with electropositive drugs such as doxorubicin (i.e., drug loading capacity >34 mg/mL, encapsulation efficiency >98%, and loading time <10 min) and an enzymatic surface-erosion degradation pattern (∼2 months) to offer sustained locoregional pharmacokinetics with long-lasting deep-tumor retention capability for TACE treatment. The microembolics demonstrated facile microcatheter deliverability in a healthy porcine liver embolization model, superior tumor-killing capacity in a rabbit VX2 liver cancer embolization model, and stabilized extravascular drug penetration depth (>3 mm for 3 months) in a rabbit ear embolization model. Importantly, the microembolics finally exhibited vessel remodeling-induced permanent embolization with minimal inflammation responses after complete degradation. Such a biodegradable ion-exchange drug carrier provides an effective and versatile strategy for enhancing long-term therapeutic responses of various local chemotherapy treatments.

Synthesis and characterization of 3-in-1 multifunctional lipiodol-doped Fe3O4@Poly (diallyl isophthalate) microspheres for arterial embolization, chemotherapy, and imaging

Transcatheter arterial embolization plays a pivotal role in treating various diseases. However, the efficacy of embolization therapy in cancer treatment can be limited by several factors, such as inevitable incomplete or non-target embolization, and the tumor recurrence and metastasis caused by the hypoxic microenvironment. Moreover, it is essential to explore simpler, more economical, and efficient methods for microsphere synthesis. Herein, we achieved one-step photocatalytic synthesis of lipiodol-doped Fe3O4@Poly (diallyliso-phthalate) multifunctional microspheres (IFeD MS) for arterial embolization, chemotherapy, and imaging. The prepared microspheres are in the shape of dried plums, with a particle size of 100-300 μm. Lipiodol demonstrates a certain degree of chemotherapeutic activity, and the incorporation of Fe3O4enables the microspheres to exhibit magnetothermal response and magnetic resonance imaging capabilities. Furthermore, the radiopaque characteristics of both agents provide the microspheres with promising potential for computed tomography and digital radiography imaging. The renal embolization experiment in rabbits demonstrated that IFeD MS achieved significant embolization and chemotherapeutic effects. Biocompatibility experiments revealed that this embolic agent did not induce tissue damage or inflammation beyond the treatment area. Additionally, IFeD MS exhibited promising imaging potential. The results of this study imply that the developed multifunctional embolic agent IFeD MS may have significant potential in transforming tumors previously only suitable for palliative cares into resectable radical treatments.

A Comparative Study of DC Beads, Callispheres and Multimodal Imaging Nano-Assembled Microspheres Loaded with Irinotecan in Vitro

Introduction: In recent years, the development of drug-eluting embolization beads that can be imaged has become a hot research topic in regard to meeting clinical needs. In our previous study, we successfully developed nano-assembled microspheres (NAMs) for multimodal imaging purposes. NAMs can not only be visualized under CT/MR/Raman imaging but can also load clinically required doses of doxorubicin. It is important to systematically compare the pharmacokinetics of NAMs with those of commercially available DC Beads and CalliSpheres to evaluate the clinical application potential of NAMs. Methods: In our study, we compared NAMs with two types of drug-eluting beads (DEBs) in terms of irinotecan, drug-loading capacity, release profiles, microsphere diameter variation, and morphological characteristics. Results: Our results indicate that NAMs had an irinotecan loading capacity similar to those of DC Beads and CalliSpheres but exhibited better sustained release in vitro. Conclusion: NAMs have great potential for application in transcatheter arterial chemoembolization for the treatment of colorectal cancer liver metastases.

Impact of particle size of multivesicular liposomes on the embolic and therapeutic effects in rabbit VX2 liver tumor

Transcatheter arterial chemoembolization (TACE) is usually considered more efficacious in the local treatment of parenchyma-sparing hepatocellular carcinoma (HCC). At present, embolic agents commonly used in TACE, include DC pellets, Hepasphere, Lipiodol, etc. Except that iodine oil is a viscous fluid embolic agent, other solid microsphere particles used clinically range from 70 to 700 µm, among which 100 to 300 µm is the most commonly used. With the technology development of micro-invasive interventional therapy, the specific distal embolization through TACE to occlude tumor arterial blood supply in patients with HCC is also required more accurately. Effective terminal embolization is considered to be a preferred option for TACE therapy due to significantly improving the survival rate of patients and preserving liver function. In this article, we prepared the multifunctional multivesicular liposomes (IVO-DOX-MVLs) (<100 µm) that can simultaneously encapsulate ioversol and doxorubicin based on the high-phase transition temperature (Tm) lipid ingredients, and evaluated its local artery embolization and therapeutic effect in rabbit VX-2 tumor model. The influence of particle size on occlusion and therapeutic effect of MVLs on rabbit VX-2 liver tumor models were well evaluated, including the tumor volume change, tumor growth rate, and necrosis rate, which were evaluated by magnetic resonance (MR). MVL samples with average particle size distribution of 50-60 µm exhibited fewer off-target embolization. Through TACE, IVO-DOX-MVLs were directly transported to the tumor tissues, playing roles of embolization performance, CT imaging effect, and local tumor killing effect. The feasibility of MVLs as a multifunctional embolic agent in its clinical application can be further improved by optimization of lipid composition and preparation process.

Development and evaluation of polyacrylamide microspheres loaded with phloretin and tantalum for transcatheter arterial embolization

Transcatheter arterial embolization is an effective treatment for liver cancer. However, the development of novel embolic agents remains a challenge. In this study, we evaluated polyacrylic acid microspheres loaded with phloretin and tantalum as potential embolic agents for liver cancer treatment. Microspheres were synthesised via emulsion polymerisation and characterised in terms of size, shape, and drug-loading efficiency. Nanosized tantalum powder (0 to 15%) was added to the microspheres as an X-ray blocking agent. The maximum drug-loading capacity of the microspheres was approximately 20 mg g-1. The phloretin-loaded microspheres showed a sustained drug release profile in vitro. The microspheres were also evaluated for their in vivo anticancer efficacy in a rabbit VX2 liver tumour model. In conclusion, polyacrylic acid microspheres loaded with phloretin and tantalum have great potential as novel embolic agents for transcatheter arterial embolization for liver cancer treatment.

Efficacy, mechanism, and safety of melatonin-loaded on thermosensitive nanogels for rabbit VX2 tumor embolization: A novel design

Transarterial chemoembolization (TACE) has been widely used for hepatocellular carcinoma. Reducing hypoxia in the tumor microenvironment after TACE remains a challenge as tumor progression is common in post-TACE patients due to the hypoxic tumor microenvironment. In this study, melatonin loaded on p(N-isopropyl-acrylamide-co-butyl methylacrylate) (PIB-M) was used for tumor embolism. Two types of human hepatoma cell lines were used to explore the mechanism by which melatonin prevents the growth and metastasis of cancer cells in vitro. A VX2 rabbit tumor model was used to evaluate the efficacy, mechanism, and safety of PIB-M in vivo. We found that under hypoxic condition, melatonin could inhibit tumor cell proliferation and migration by targeting hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGF-A) in vitro. In vivo, PIB-M inhibited tumor growth and metastasis in rabbit VX2 tumors by promoting apoptosis of tumor cells and targeting related angiogenic proteins and vascular permeability proteins. A high concentration of melatonin in the PIB-M group could be maintained in tumor tissue for 72 h after embolization. The liver and kidney functions were most damaged on the first day but recovered to normal on the seventh day after embolization in the PIB-M group. This novel method may open avenues for reduction of tumor growth and metastasis after TACE and is efficacy and safety, which may be used for treatment for other solid tumors and clinical translation.

Design of an imaging magnetic microsphere based on photopolymerization for magnetic hyperthermia in tumor therapy

Magnetic hyperthermia therapy has been widely used in the nonsurgical treatment of patients with advanced stage cancers that cannot be treated by surgery. It is minimally invasive, precise, and highly efficient and has a good curative effect. In this paper, a magnetic microsphere with Fe3O4 was prepared for thermal therapy and imaging based on a photoinitiated suspension polymerization method from biallelic monomers. The preparation method clearly minimized the degradative chain transfer of allyl polymerization reactions. The microspheres were characterized by microscope observation, spectral analysis, thermal analysis, and magnetic testing. The magnetothermal effect was detected by an infrared thermal imager in vitro and in vivo under a high-frequency alternating magnetic field (AMF). The antitumor effect was verified by testing the viability of H22 cells and observing a tumor-bearing mouse model under high-frequency AMF. Biocompatibility was evaluated by cell viability assay, tissue section observation, and blood biochemical analysis. The imaging capacity was tested by X-ray, MRI, and CT imaging experiments. The results show that the product has good dispersibility, thermal stability, superparamagnetism, and biocompatibility. Under the action of an AMF, the magnetic hyperthermia effect in tumor-bearing mice was better, and an antitumor effect could be achieved.

Exploiting targeted nanomedicine for surveillance, diagnosis, and treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the cancers that has the highest morbidity and mortality rates. In clinical practice, there are still many limitations in surveilling, diagnosing, and treating HCC, such as the poor detection of early HCC, the frequent post-surgery recurrence, the low local tumor control rate, the therapy resistance and side effects. Therefore, improved, or innovative modalities are urgently required for early diagnosis as well as refined and effective management. In recent years, nanotechnology research in the field of HCC has received great attention, with various aspects of diagnosis and treatment including biomarkers, ultrasound, diagnostic imaging, intraoperative imaging, ablation, transarterial chemoembolization, radiotherapy, and systemic therapy. Different from previous reviews that discussed from the perspective of nanoparticles' structure, design and function, this review systematically summarizes the methods and limitations of diagnosing and treating HCC in clinical guidelines and practices, as well as nanomedicine applications. Nanomedicine can overcome the limitations to improve diagnosis accuracy and therapeutic effect via enhancement of targeting, biocompatibility, bioavailability, controlled releasing, and combination of different clinical treatment modalities. Through an in-depth understanding of the logic of nanotechnology to conquer clinical limitations, the main research directions of nanotechnology in HCC are sorted out in this review. It is anticipated that nanomedicine will play a significant role in the future clinical practices of HCC.

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.

Monodisperse CaCO3-loaded gelatin microspheres for reversing lactic acid-induced chemotherapy resistance during TACE treatment

Transarterial chemoembolization (TACE) is an important approach for the treatment of unresectable hepatocellular carcinoma (HCC). However, the lactic acid-induced acidic tumor microenvironment (TME) may reduce the therapeutic outcome of TACE. Herein, monodispersed gelatin microspheres loaded with calcium carbonate nanoparticles (CaNPs@Gel-MS) as novel embolic agents were prepared by a simplified microfluidic device. It was found that the particle size and homogeneity of as-prepared CaNPs@Gel-MS were strongly dependent on the flow rates of continuous and dispersed phases, and the inner diameter of syringe needle. The introduction of CaNPs provided the gelatin microspheres with an enhanced ability to encapsulate the chemotherapeutic drug of DOX, as well as a pH-responsive sustained drug release behavior. In vitro results revealed that CaNPs@Gel-MS could largely increase the cellular uptake and chemotoxicity of DOX by neutralizing the lactic acid in the culture medium. In addition, CaNPs@Gel-MS exhibited an excellent and persistent embolic efficiency in a rabbit renal model. Finally, we found that TACE treatment with DOX-loaded CaNPs@Gel-MS (DOX/CaNPs@Gel-MS) had a much stronger ability to inhibit tumor growth than the DOX-loaded gelatin microspheres without CaNPs (DOX@Gel-MS). Overall, CaNPs@Gel-MS could be a promising embolic microsphere that can significantly improve anti-HCC ability by reversing lactic acid-induced chemotherapy resistance during TACE treatment.

Monometallic and alloy nanoparticles: a review of biomedical applications

Current intrinsic deficiencies in biomedicine promote the rapid development of alternative multitasking approaches. Recently, monometallic and alloy nanoparticles (NPs) have been widely studied for their potential biomedical applications. However, the research mainly focuses on monometallic compounds and metal oxide NPs that have already been studied. In this review, we investigate promising modified mono- and bimetallic NPs for improving the current state of materials science in medicine. It was contended that effective general biomedical applications can be enhanced by intelligent NP design. Particularly, we discuss transition and platinum metal compositions, iron-based and non-iron compounds, along with liquid alloys. Subsequently, we explore the capabilities provided by modifications such as inorganic and organic coatings, polymers, and biomolecules that can invent new NP designs for precise applications, ultimately resulting in an improved patient outcome. We provide a comprehensive assessment of the advantages and limitations of monometallic and alloy nanomaterials and possible solutions to problems that delay their development.

Multifunctional nanoplatforms application in the transcatheter chemoembolization against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has the sixth-highest new incidence and fourth-highest mortality worldwide. Transarterial chemoembolization (TACE) is one of the primary treatment strategies for unresectable HCC. However, the therapeutic effect is still unsatisfactory due to the insufficient distribution of antineoplastic drugs in tumor tissues and the worsened post-embolization tumor microenvironment (TME, e.g., hypoxia and reduced pH). Recently, using nanomaterials as a drug delivery platform for TACE therapy of HCC has been a research hotspot. With the development of nanotechnology, multifunctional nanoplatforms have been developed to embolize the tumor vasculature, creating conditions for improving the distribution and bioavailability of drugs in tumor tissues. Currently, the researchers are focusing on functionalizing nanomaterials to achieve high drug loading efficacy, thorough vascular embolization, tumor targeting, controlled sustained release of drugs, and real-time imaging in the TACE process to facilitate precise embolization and enable therapeutic procedures follow-up imaging of tumor lesions. Herein, we summarized the recent advances and applications of functionalized nanomaterials based on TACE against HCC, believing that developing these functionalized nanoplatforms may be a promising approach for improving the TACE therapeutic effect of HCC.

Smart nanoparticles and microbeads for interventional embolization therapy of liver cancer: state of the art

The process of transcatheter arterial chemoembolization is characterized by the ability to accurately deliver chemotherapy drugs with minimal systemic side effects and has become the standard treatment for unresectable intermediate hepatocellular carcinoma (HCC). However, this treatment option still has much room for improvement, one of which may be the introduction of nanomaterials, which exhibit unique functions and can be applied to in vivo tumor imaging and therapy. Several biodegradable and multifunctional nanomaterials and nanobeads have recently been developed and applied in the locoregional treatment of hepatocellular cancer. This review explores recent developments and findings in relation to micro-nano medicines in transarterial therapy for HCC, emerging strategies to improve the efficacy of delivering nano-based medicines, and expounding prospects for clinical applications of nanomaterials.

A thermosensitive Pickering gel emulsion with a high oil-water ratio for long-term X-ray imaging and permanent embolization of arteries

Iodized oil has an excellent X-ray imaging effect, but it shows poor embolization performance. When used as an embolic agent, it is easily washed off by the blood flow and eliminated from the body. Therefore, it is essential to use iodized oil in combination with solid embolic agents such as gelatin sponge or to perform multiple embolization procedures to achieve the therapeutic effect. In the present study, a poly(N-isopropyl acrylamide)-co-acrylic acid (PNCAA) temperature-sensitive nanogel was synthesized by emulsion polymerization; the nanogel was then emulsified with iodized oil to prepare a thermosensitive iodized oil Pickering gel emulsion (TIPE). The oil-water (O/W) ratio of an O/W emulsion system can reach 4 : 6. When injected into the body, TIPE transforms into a nonflowing coagulated state at physiological temperature; the iodized oil is locked in the emulsion structure, thereby achieving local embolization and continuous imaging effects, which not only retain the X-ray imaging effect of the iodized oil but also improve its embolization effect. Subsequently, we further evaluated renal artery embolization in a normal rabbit renal artery model, and the results showed that TIPE shows a long-term conformal embolization performance and excellent long-term X-ray imaging ability.

Bench-to-bedside development of multifunctional flexible embolic agents

Transarterial chemoembolization (TACE) has been demonstrated to provide a survival benefit for patients with unresectable hepatocellular carcinoma (HCC). However, conventional TACE still faces limitations associated with complications, side effects, unsatisfactory tumor responses, repeated treatment, and narrow indications. For further improvement of TACE, additional beneficial functions such as degradability, drug-loading and releasing properties, detectability, targetability, and multiple therapeutic modalities were introduced. The purpose here is to provide a comprehensive overview of current and emerging particulate embolization technology with respect to materials. Therefore, this review systematically identified and described typical features, various functions, and practical applications of recently emerging micro/nano materials as particulate embolic agents for TACE. Besides, new insights into the liquid metals-based multifunctional and flexible embolic agents were highlighted. The current development routes and future outlooks of these micro/nano embolic materials were also presented to promote advancement in the field.

Renal and hepatic artery embolization with Pickering gel emulsion of lipiodol in rabbit

OBJECTIVE

This research aimed to evaluate the feasibility of a novel liquid embolic agent Pickering gel emulsion of lipiodol (PGEL) for renal and hepatic artery embolization in the rabbit experimental model.

METHODS

Embolization was performed in the right renal artery of 24 adult New Zealand White rabbits and 24 VX2 tumors in the left liver lobe. The rabbits were randomly allocated to four treatment groups (n = 6 per group): (A) normal saline (NS), (B) lipiodol, (C) 180-300 μm polyvinyl alcohol (PVA), and (D) PGEL.

RESULTS

Renal artery embolization in normal rabbits and transarterial embolization (TAE) in VX2 tumor-bearing rabbits indicated that PGEL achieved a better embolization effect for a longer time than lipiodol and PVA. The tumor growth ratio of the PGEL group was significantly lower than that of the NS, lipiodol, and PVA groups at 3 (P < 0.001) and 7 (P < 0.001) days after embolization. In addition, hematoxylin and eosin and immunohistochemical staining revealed that the tumor necrosis ratio was higher in the PGEL group than in the NS, lipiodol, and PVA groups (P < 0.01), and the expression levels of HIF-1α, VEGF, and CD31 decreased after PGEL embolization compared with the lipiodol and PVA treatments.

CONCLUSION

PGEL is an effective embolic material that provides immediate and total occlusion of the renal artery and may be a potential therapeutic embolic agent for TAE of HCC.

The role of imaging in targeted delivery of nanomedicine for cancer therapy

Nanomedicines overcome the pharmacokinetic limitations of traditional drug formulations and have promising prospect in cancer treatment. However, nanomedicine delivery in vivo is still facing challenges from the complex physiological environment. For the purpose of effective tumor therapy, they should be designed to guarantee the five features principle, including long blood circulation, efficient tumor accumulation, deep matrix penetration, enhanced cell internalization and accurate drug release. To ensure the excellent performance of the designed nanomedicine, it would be better to monitor the drug delivery process as well as the therapeutic effects by real-time imaging. In this review, we summarize strategies in developing nanomedicines for efficiently meeting the five features of drug delivery, and the role of several imaging modalities (fluorescent imaging (FL), magnetic resonance imaging (MRI), computed tomography (CT), photoacoustic imaging (PAI), positron emission tomography (PET), and electron microscopy) in tracing drug delivery and therapeutic effect in vivo based on five features principle.

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.

Shape-Anisotropic Microembolics Generated by Microfluidic Synthesis for Transarterial Embolization Treatment

Particulate embolic agents with calibrated sizes, which employ interventional procedures to achieve endovascular embolization, have recently attracted tremendous interest in therapeutic embolotherapies for a wide plethora of diseases. However, the particulate shape effect, which may play a critical role in embolization performances, has been rarely investigated. Here, polyvinyl alcohol (PVA)-based shape-anisotropic microembolics are developed using a facile droplet-based microfluidic fabrication method via heat-accelerated PVA-glutaraldehyde crosslinking reaction at a mild temperature of 38 ^° C. Precise geometrical controls of the microembolics are achieved with a nearly capsule shape through regulating surfactant concentration and flow rate ratio between dispersed phase and continuous phase in the microfluidics. Two specific models are employed, i.e., in vitro decellularized rabbit liver embolization model and in vivo rabbit ear embolization model, to systematically evaluate the embolization behaviors of the nonspherical microembolics. Compared to microspheres of the same volume, the elongated microembolics demonstrated advantageous endovascular navigation capability, penetration depth and embolization stability due to their comparatively smaller radial diameter and their central cylindrical part providing larger contact area with distal vessels. Such nonspherical microembolics present a promising platform to apply shape anisotropy to achieve distinctive therapeutic effects for endovascular treatments.

Recent advances and applications of microspheres and nanoparticles in transarterial chemoembolization for hepatocellular carcinoma

Transarterial chemoembolization (TACE) is a recommended treatment for patients suffering from intermediate and advanced hepatocellular carcinoma (HCC). As compared to the conventional TACE, drug-eluting bead TACE demonstrates several advantages in terms of survival, treatment response, and adverse effects. The selection of embolic agents is critical to the success of TACE. Many studies have been performed on the modification of the structure, size, homogeneity, biocompatibility, and biodegradability of embolic agents. Continuing efforts are focused on efficient loading of versatile chemotherapeutics, controlled sizes for sufficient occlusion, real-time detection intra- and post-procedure, and multimodality imaging-guided precise treatment. Here, we summarize recent advances and applications of microspheres and nanoparticles in TACE for HCC. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

The sodium hyaluronate microspheres fabricated by solution drying for transcatheter arterial embolization

Transcatheter arterial embolization (TAE) is an effective therapeutic method for several clinical ailments. Interminably, the polymer microsphere is reflected as one of the idyllic embolic materials due to the exceptional...

2D MXene Nanomaterials for Versatile Biomedical Applications: Current Trends and Future Prospects

Research on 2D nanomaterials is still in its early stages. Most studies have focused on elucidating the unique properties of the materials, whereas only few reports have described the biomedical applications of 2D nanomaterials. Recently, important questions about the interaction of 2D MXene nanomaterials with biological components have been raised. 2D MXenes are monolayer atomic nanosheets derived from MAX phase ceramics. As a new type of inorganic nanosystems, they are being widely used in biology and biomedicine. This review introduces the latest developments in 2D MXenes for the most advanced biomedical applications, including preparation and surface modification strategies, treatment modes, drug delivery, antibacterial activity, bioimaging, sensing, and biocompatibility. Besides, this review also discusses the current development trends and prospects of 2D inorganic nanosheets for further clinical applications. These emerging 2D inorganic MXenes will play an important role in next-generation cancer treatments.

Intrinsically radiopaque biomaterial assortments: a short review on the physical principles, X-ray imageability, and state-of-the-art developments

X-ray attenuation ability, otherwise known as radiopacity of a material, could be indisputably tagged as the central and decisive parameter that produces contrast in an X-ray image. Radiopaque biomaterials are vital in the healthcare sector that helps clinicians to track them unambiguously during pre and post interventional radiological procedures. Medical imaging is one of the most powerful resources in the diagnostic sector that aids improved treatment outcomes for patients. Intrinsically radiopaque biomaterials enable themselves for visual targeting/positioning as well as to monitor their fate and further provide the radiologists with critical insights about the surgical site. Moreover, the emergence of advanced real-time imaging modalities is a boon to the contemporary healthcare systems that allow to perform minimally invasive surgical procedures and thereby reduce the healthcare costs and minimize patient trauma. X-ray based imaging is one such technologically upgraded diagnostic tool with many variants like digital X-ray, computed tomography, digital subtraction angiography, and fluoroscopy. In light of these facts, this review is aimed to briefly consolidate the physical principles of X-ray attenuation by a radiopaque material, measurement of radiopacity, classification of radiopaque biomaterials, and their recent advanced applications.

Biodegradable poly(lactide-co-glycolide) microspheres encapsulating hydrophobic contrast agents for transarterial chemoembolization

Transarterial chemoembolization (TACE) is a therapeutic approach to address hepatocellular carcinoma by obstructing the blood supply to the tumor using embolic agents and improving the local delivery of anticancer agents. Size-calibrated polymeric microspheres (MSs) termed drug-eluting beads (DEBs) are the most prevalent solid embolic materials; however, their limitations include insufficient X-ray visibility or biodegradability. In this study, size-controlled polymeric MSs with inherent radiopacity and biodegradability were created, and their embolic effect was assessed. Poly(lactide-co-glycolide) MSs (PLGA MSs) incorporating a hydrophobic X-ray contrast agent and an anticancer drug were produced by the w/o/w emulsion process. Their sizes were exactly calibrated to 71.40 ± 32.18 and 142.66 ± 59.92 μm in diameter, respectively, which were confirmed to have sizes similar to the clinically available DEBs. The iodine content of PLGA MSs was calculated as 144 mgI/g, and the loading quantity of the drug was 1.33%. Manufactured PLGA MSs were gradually degraded for 10 weeks and consistently released the anticancer drug. Following the PLGA MSs injection into the renal artery of New Zealand white rabbit test subjects, their deliverability to the targeted vessel through the microcatheter was confirmed. Injected PLGA MSs were clearly imaged through the real-time X-ray device without blending any contrast agents. The embolic effect of the PLGA MSs was ultimately established by the atrophy of an embolized kidney after 8 weeks. Consequently, the designed PLGA MS is anticipated to be an encouraging prospect to address hepatocellular carcinoma.

Comparison of interventions and outcomes of enhanced recovery after surgery: a systematic review and meta-analysis of 2456 adolescent idiopathic scoliosis cases

PURPOSE

The objective of this meta-analysis and systematic review is to compare the methodology and evaluate the efficacy of Enhanced recovery after Spine Surgery (ERAS) for adolescent idiopathic scoliosis (AIS) and to compare the outcomes with traditional discharge (TD) pathways.

METHODS

Using major databases, a systematic search was performed. Studies comparing the implementation of ERAS or ERAS-like and TD pathways in patients with AIS were identified. Data regarding methodology and outcomes were collected and analyzed.

RESULTS

Fourteen studies (n = 2456) were included, comprising 1081 TD and 1375 ERAS or ERAS-like patients. Average age of patients was 14.6 ± 0.4 years. Surgical duration was on average 35.6 min shorter for the ERAS group compared to TD cohort ([2.8, 68.3], p = 0.03), and blood loss was 112.3 milliliters less ([102.4, 122.2], p < 0.00001). ERAS group reached first ambulation 29.6 h earlier ([11.2, 48.0], p-0.002), patient-controlled-analgesia (PCA) discontinuation 0.53 day earlier ([0.4, 0.6], p < 0.00001), urinary catheter discontinuation 0.5 day earlier ([0.4, 0.6], p < 0.00001), and length-of-stay (LOS) was 1.6 days shorter ([1.4, 1.8], p < 0.00001). Rates of complications and 30-day-readmission-to-hospital were similar between both groups. Pain scores were significantly lower for ERAS group on days 0 through 2 post-operatively.

CONCLUSIONS

Use of ERAS after AIS is safe and effective, decreasing surgical duration and blood loss. ERAS methodology effectively focused on reducing time to first ambulation, PCA discontinuation, and urinary catheter removal. Outcomes showed significantly decreased LOS without a significant increase in complications. There should be efforts to incorporate ERAS in AIS surgery. Further studies are necessary to assess patient satisfaction.

LEVEL OF EVIDENCE III

Meta-analysis of Level 3 studies.

Sustained-Release and pH-Adjusted Alginate Microspheres-Encapsulated Doxorubicin Inhibit the Viabilities in Hepatocellular Carcinoma-Derived Cells

The objective of this study aimed to develop biodegradable calcium alginate microspheres carrying doxorubicin (Dox) at the micrometer-scale for sustained release and the capacity of pH regulatory for transarterial chemoembolization. Ultrasonic atomization and CaCl₂ cross-linking technologies were used to prepare the microspheres. A 4-by-5 experiment was first designed to identify imperative parameters. The concentration of CaCl₂ and the flow rate of the pump were found to be critical to generate microspheres with a constant volume median diameter (~39 μm) across five groups with different alginate: NaHCO₃ ratios using each corresponding flow rate. In each group, the encapsulation efficiency was positively correlated to the Dox-loading %. Fourier-transform infrared spectroscopy showed that NaHCO₃ and Dox were step-by-step incorporated into the calcium alginate microspheres successfully. Microspheres containing alginate: NaHCO₃ = 1 exhibited rough and porous surfaces, high Young’s modulus, and hardness. In each group with the same alginate: NaHCO₃ ratio, the swelling rates of microspheres were higher in PBS containing 10% FBS compared to those in PBS alone. Microspheres with relatively high NaHCO₃ concentrations in PBS containing 10% FBS maintained better physiological pH and higher accumulated Dox release ratios. In two distinct hepatocellular carcinoma-derived cell lines, treatments with microspheres carrying Dox demonstrated that the cell viabilities decreased in groups with relatively high NaHCO₃ ratios in time- and dose-dependent manners. Our results suggested that biodegradable alginate microspheres containing relatively high NaHCO₃ concentrations improved the cytotoxicity effects in vitro.

Biocompatible copper sulfide-based nanocomposites for artery interventional chemo-photothermal therapy of orthotropic hepatocellular carcinoma

Transcatheter arterial embolization has been considered as a promising targeted delivery approach for hepatocellular carcinoma (HCC). Currently, chemoembolization was the main treatment for unresectable HCC. However, the traditional chemoembolization treatment suffers from undesirable therapeutic effects and serious side-effects. In this study, the doxorubicin (DOX)-encapsulated and near-infrared (NIR)-responsible copper sulfide (CuS)-based nanotherapeutics was developed for magnetic resonance imaging (MRI)-guided chemo-photothermal therapy of HCC tumor in rats. The DOX-loaded CuS nanocomposites (DOX@BSA-CuS) demonstrated distinct NIR-triggered drug release behavior and high photothermal effect. In an orthotopic HCC rat model, DOX@BSA-CuS nanocomposites were selectively delivered to the tumor site via the intra-arterial transcatheter. The proposed DOX@BSA-CuS nanocomposites plus NIR laser irradiation exhibited significant tumor growth suppression performance. Moreover, the treatment progress can be monitored by MRI images. Finally, the preliminary toxicity estimate suggested the negligible side-effect of DOX@BSA-CuS nanocomposites during the therapeutic process. These results suggest the clinical translational potential possibility for imaging-guided arterial embolization with DOX@BSA-CuS nanocomposites for the treatment of HCC.

Fabrication of Fe3O4@PVA microspheres by one-step electrospray for magnetic resonance imaging during transcatheter arterial embolization

Magnetic resonance imaging (MRI) has attracted increasing attention as a feasible alternative or adjunctive imaging modality for X-ray digital subtraction angiography because of the high tissue resolution and non-ionization radiation. In this study, a one-step electrospray method was developed to fabricate PVA microspheres encapsulated with in situ synthesized Fe₃O₄ nanoparticles. Fe₃O₄@PVA microspheres were mono-dispersed black spheres with a wide range of sizes (262-958 µm). The in situ-synthesized Fe₃O₄ nanoparticles were used as the contrast agent of MRI and the cross-linkers of PVA matrixes for the embolization purpose. In vivo evaluation of renal arteries of normal rabbits showed that Fe₃O₄@PVA microspheres had good embolic effect and enhanced capability of MRI. In vitro and in vivo biosafety assessment confirmed that Fe₃O₄@PVA microspheres had favorable biocompatibility. The DOX-loaded Fe₃O₄@PVA microspheres showed a typical drug-sustained release profile. These results suggest that the prepared DOX-loaded Fe₃O₄@PVA microspheres have the function of MRI, embolotherapy and chemotherapy. We expect our study could provide a simple and useful approach for the systematic design, fabrication, and application of a new type of magnetic microspheres as a triple-functional embolic agent for the development of MRI-guided TACE. STATEMENT OF SIGNIFICANCE: Due to the low tissue resolution and hazardous ionization radiation of X-ray digital subtraction angiography, it is beneficial to study MR imaging embolic microspheres for the development of MRI-guided TACE. In this study, a one-step electrospray method was firstly developed to fabricate PVA microspheres encapsulated with in situ synthesized Fe₃O₄ nanoparticles. Then, chemotherapeutic agent (DOX), contrast media of MRI (Fe₃O₄) and embolic agent (PVA matrix) were combined together in one body (DOX-loaded Fe₃O₄@PVA microspheres) to achieve the triple effects of chemotherapy, MR imaging and embolization. This triple-functional embolic agent offers potential for the future development of MRI-guided TACE.

Magnetic mesoporous embolic microspheres in transcatheter arterial chemoembolization for liver cancer

Transcatheter arterial chemoembolization (TACE) is the main treatment for liver cancer. Although many embolic agents have been exploited in TACE, embolic agents combining embolization, drug loading, and imaging properties have not yet been constructed. Herein, we report a new magnetic mesoporous embolic microsphere that can simultaneously be loaded with doxorubicin (Dox), block vessels, and be observed by magnetic resonance imaging (MRI). The microspheres were prepared by decorating magnetic polystyrene/Fe₃O₄ particles with mesoporous organosilica microparticles (denoted as PS/Fe₃O₄@MONs). The PS/Fe₃O₄@MONs were uniformly spherical and large (50 µm), with a high specific surface area, uniform mesopores, and a Dox loading capacity of 460.8 µg mg^-1. Dox-loaded PS/Fe₃O₄@MONs (PS/Fe₃O₄@MON@Dox) effectively inhibited liver cancer cell growth. A VX2 rabbit liver tumor model was constructed to study the efficacy of TACE with PS/Fe₃O₄@MON@Dox. In vivo, PS/Fe₃O₄@MON@Dox could be smoothly delivered through an arterial catheter to achieve chemoembolization. Moreover, PS/Fe₃O₄@MON@Dox and residual tumor parenchyma could be distinguished on MRI, which is of great significance for evaluating the efficacy of TACE. Histopathology showed that PS/Fe₃O₄@MON@Dox could be deposited in the tumor vessels, completely blocking the blood supply. Overall, PS/Fe₃O₄@MON@Dox showed good drug loading, embolization and imaging performance as well as potential for use in TACE. STATEMENT OF SIGNIFICANCE: Transcatheter arterial chemoembolization (TACE) is the main treatment for liver cancer. Although many embolic agents have been exploited in TACE, embolic agents combining embolization, drug-loading, and imaging properties have not yet been constructed. In this work, we prepared magnetic mesoporous microspheres as a new embolic agent that can simultaneously load doxorubicin (Dox), block blood vessels and enable magnetic resonance imaging. Overall, this new embolic microsphere-mediated TACE strategy for liver cancer showed good therapeutic effects, and the PS/Fe₃O₄@MON@Dox embolic microspheres provide a new avenue for improving the efficacy of TACE for liver cancer and postoperative evaluation.

Magnetic liquid metal loaded nano-in-micro spheres as fully flexible theranostic agents for SMART embolization

Transcatheter arterial chemoembolization (TACE) has become one of the preferred choices for advanced liver cancer patients. Current clinically used microsphere embolic agents, such as PVA, gelatin, and alginate microspheres, have limited therapeutic efficacy and lack the function of real-time imaging. In this work, we fabricated magnetic liquid metal nanoparticle (Fe@EGaIn NP) loaded calcium alginate (CA) microspheres (denoted as Fe@EGaIn/CA microspheres), which integrate CT/MR dual-modality imaging and photothermal/photodynamic functions of the Fe@EGaIn NP core, as well as embolization and drug-loading functions of CA microspheres. Namely, such nano-in-micro spheres can be used as fully flexible theranostic agents to achieve smart-chemoembolization. It has been confirmed by in vitro and in vivo experiments that Fe@EGaIn/CA microspheres have advantageous morphology, favorable biocompatibility, splendid versatility, and advanced embolic efficacy. Benefiting from these properties, excellent therapeutic efficiency was achieved with a tumor growth-inhibiting value of 100% in tumor-bearing rabbits. As a novel microsphere embolic agent with promising therapeutic efficacy and diagnostic capability, Fe@EGaIn/CA microspheres have shown potential applications in clinical transcatheter arterial chemoembolization. And the preparation strategy presented here provides a generalized paradigm for achieving multifunctional and fully flexible theranostics.

Nanotechnology for Hepatocellular Carcinoma: From Surveillance, Diagnosis to Management

Hepatocellular carcinoma (HCC) remains the fourth leading cause of cancer-related death worldwide. However, the clinical diagnosis and treatment modalities are still relatively limited, which urgently require the development of new effective technologies. Recently, nanotechnology has gained extensive attention in HCC surveillance, imaging and pathological diagnosis, and therapeutic strategies. Typically, nanomedicines have been focused on early HCC diagnosis and precise treatment of advanced HCC, which has developed and improved a variety of new technologies and agents for future clinical practice. Furthermore, strategies of facilitating drug release and delivery in current treatment processes such as ablation, systematic therapy, transcatheter arterial chemoembolization, molecular targeted therapy, and immune-modulating therapy have also been studied widely. This review summarizes the recent advances in this area according to current clinical HCC guidelines: 1) Nanoparticle-based HCC surveillance; 2) Nanotechnology for HCC diagnosis; 3) Therapeutic advances for HCC Management; 4) Limitations of applications in nanotechnology for HCC; 5) Conclusions and perspectives. Although there are still many limitations and difficulties to overcome, the investigations of nanomedicines are believed to show potential applications in clinical practice.

Synthesis, characterization, and imaging of radiopaque bismuth beads for image-guided transarterial embolization

Current therapy for hypervascular cancers, e.g., hepatocellular carcinoma, includes occlusion of the tumor blood supply by arterial infusion of embolic microspheres (beads) suspended in iodine-based contrast under fluoroscopic guidance. Available radiopaque, imageable beads use iodine as the radiopacifier and cannot be differentiated from contrast. This study aimed to synthesize and characterize imageable beads using bismuth as the radiopacifier that could be distinguished from iodine contrast based upon the difference in the binding energy of k-shell electrons (k-edge). Radiodense bismuth beads were successfully synthesized some with uniform bismuth distribution across the beads. The beads were spherical and could be infused through clinical microcatheters. The bismuth beads could be imaged with clinical dual-energy computed tomography (CT), where iodine-based contrast could be distinguished from the microspheres. The ability to separate iodine from bismuth may enhance the diagnostic information acquired on follow-up CT, identifying the distribution of the embolic beads separately from the contrast. Furthermore, with sequential use of iodine- and bismuth-based beads, the two radiopaque beads could be spatially distinguished on imaging, which may enable the development of dual drug delivery and dual tracking.

Immobilized thrombin on X-ray radiopaque polyvinyl alcohol/chitosan embolic microspheres for precise localization and topical blood coagulation

Trans-catheter arterial embolization (TAE) plays an important role in treating various diseases. The available embolic agents lack X-ray visibility and do not prevent the reflux phenomenon, thus hindering their application for TAE therapy. Herein, we aim to develop a multifunctional embolic agent that combines the X-ray radiopacity with local procoagulant activity. The barium sulfate nanoparticles (BaSO₄ NPs) were synthesized and loaded into the polyvinyl alcohol/chitosan (PVA/CS) to prepare the radiopaque BaSO₄/PVA/CS microspheres (MS). Thereafter, thrombin was immobilized onto the BaSO₄/PVA/CS MS to obtain the thrombin@BaSO₄/PVA/CS MS. The prepared BaSO₄/PVA/CS MS were highly spherical with diameters ranging from 100 to 300 μm. In vitro CT imaging showed increased X-ray visibility of BaSO₄/PVA/CS MS with the increased content of BaSO₄ NPs in the PVA/CS MS. The biocompatibility assessments demonstrated that the MS were non-cytotoxic and possessed permissible hemolysis rate. The biofunctionalized thrombin@BaSO₄/PVA/CS MS showed improved hemostatic capacity and facilitated hemostasis in vitro. Additionally, in vivo study performed on a rabbit ear embolization model confirmed the excellent X-ray radiopaque stability of the BaSO₄/PVA/CS MS. Moreover, both the BaSO₄/PVA/CS and thrombin@BaSO₄/PVA/CS MS achieved superior embolization effects with progressive ischemic necrosis on the ear tissue and induced prominent ultrastructural changes in the endothelial cells. The findings of this study suggest that the developed MS could act as a radiopaque and hemostatic embolic agent to improve the embolization efficiency.

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Excellent in vitro and in vivo visibility of BaSO₄/PVA/CS MS.

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Excellent cytocompatibility and hemocompatibility of BaSO₄/PVA/CS MS.

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Enhanced hemostatic capacity and hemostasis of thrombin@BaSO₄/PVA/CS MS.

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Potential application of thrombin@BaSO₄/PVA/CS MS for in vivo embolization.

Microfluidic-prepared, monodisperse, X-ray-visible, embolic microspheres for non-oncological embolization applications

Embolotherapy using particle embolics is normally performed with exogenous contrast to assist in visualization. However, the exact location of the embolics cannot be identified after contrast washout. We developed a novel, pseudo-check valve-integrated microfluidic device, that partitions barium- impregnated alginate from crosslinking solution, thereby preventing nozzle failure. This enables rapid and continuous generation of inherently X-ray-visible embolic microspheres (XEMs) with uniform size. The XEMs are visible under clinical X-ray and cone beam CT both in vitro and in vivo. In particular, we demonstrated the embolization properties of these XEMs in large animals, performing direct intra- and post-procedural assessment of embolic delivery. The persistent radiopacity of these XEMs enables real-time evaluation of embolization precision and offers great promise for non-invasive follow-up examination without exogenous contrast. We also demonstrated that bariatric arterial embolization with XEMs significantly suppresses weight gain in swine, as an example of a non-oncological application of embolotherapy.

A cancer invasion model of cancer-associated fibroblasts aggregates combined with TGF-β1 release system

Introduction

The objective of this study is to design a cancer invasion model where the cancer invasion rate can be regulated in vitro.

Methods

Cancer-associated fibroblasts (CAF) aggregates incorporating gelatin hydrogel microspheres (GM) containing various concentrations of transforming growth factor-β1 (TGF-β1) (CAF-GM-TGF-β1) were prepared. Alpha-smooth muscle actin (α-SMA) for the CAF aggregates was measured to investigate the CAF activation level by changing the concentration of TGF-β1. An invasion assay was performed to evaluate the cancer invasion rate by co-cultured of cancer cells with various CAF-GM-TGF-β1.

Results

The expression level of α-SMA for CAF increased with an increased in the TGF-β1 concentration. When co-cultured with various types of CAF-GM-TGF-β1, the cancer invasion rate was well correlated with the α-SMA level. It is conceivable that the TGF-β1 concentration could modify the level of CAF activation, leading to the invasion rate of cancer cells. In addition, at the high concentrations of TGF-β1, the effect of a matrix metalloproteinase (MMP) inhibitor on the cancer invasion rate was observed. The higher invasion rate would be achieved through the higher MMP production.

Conclusions

The present model is promising to realize the cancer invasion whose rate can be modified by changing the TGF-β1 concentration.

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This invasion model would be a promising tool for anti-cancer drug screening.

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TGF-β1 was controlled release from gelatin hydrogel microspheres.

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CAF were activated by increased TGF-β1 concentration.

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There was a good correlation between invasion rate and TGF-β1 concentration.

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Higher invasion rate would be achieved through matrix metalloproteinase production.

Smart Nanotherapeutic Targeting of Tumor Vasculature

The past decades have witnessed the development of a field dedicated to targeting tumor vasculature for cancer therapy. In contrast to conventional chemotherapeutics that need to penetrate into tumor tissues for killing tumor cells, the agents targeting tumor vascular system have two major advantages: direct contact with vascular endothelial cells or the blood and less possibility to induce drug resistance because of high gene stability of endothelial cells. More specifically, various angiogenesis inhibitors (AIs) and vascular disrupting agents (VDAs) that block tumor blood supply to inhibit tumor progression, some of which have been applied clinically, have been described. However, off-target effects and high effective doses limit the utility of these formulations in cancer patients. Thus, new strategies with improved therapeutic efficacy and safety are needed for tumor vessel targeting therapy. With the burgeoning developments in nanotechnology, smart nanotherapeutics now offer unprecedented potential for targeting tumor vasculature. Based on specific structural and functional features of the tumor vasculature, a number of different nanoscale delivery systems have been proposed for cancer therapy. In this Account, we summarize several distinct strategies to modulate tumor vasculature with various smart nanotherapeutics for safe and effective tumor therapy developed by our research programs. Inspired by the blood coagulation cascade, we generated nanoparticle-mediated tumor vessel infarction strategies that selectively block tumor blood supply to starve the tumor to death. By specifically delivering thrombin loaded DNA nanorobots (Nanorobot-Th) into tumor vessels, an intratumoral thrombosis is triggered to induce vascular infarction and, ultimately, tumor necrosis. Mimicking the coagulation cascade, a smart polymeric nanogel achieves permanent and peripheral embolization of liver tumors. Considering the critical role of platelets in maintaining tumor vessel integrity, a hybrid (PLP-D-R) nanoparticle selectively depleting tumor-associated platelets (TAP) to boost tumor vessel permeability was developed for enhancing intratumoral drug accumulation. In addition, benefiting from a better understanding of the molecular and cellular underpinnings of vascular normalization, several tumor acidity responsive nanotherapeutics, encapsulating therapeutic peptides, and small interfering RNA were developed to correct the abnormal features of the tumor vasculature. This made the tumor vessels more efficient for drug delivery. While we are still exploring the mechanisms of action of these novel nanoformulations, we expect that the strategies summarized here will offer a promising platform to design effective next-generation nanotherapeutics against cancer and facilitate the clinical translation of smart nanotherapeutics that target tumor vasculature.

Advances in Biomaterials and Technologies for Vascular Embolization

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

The opacity of mineral ion-loaded bead (DC beads®) on low-keV monochromatic images from dual energy CT and T1-weighted gradient-echo MRI

PURPOSE

To evaluate the opacity of DC beads^® (DCB) loaded with mineral ions on low-keV monochromatic images from dual energy computed tomography (DECT) and T1-weighted gradient-echo (T1-GRE) MRI.

MATERIALS AND METHODS

Fe²⁺ or Ca²⁺-loaded DCBs were prepared by mixing DCBs in 100 mM FeSO₄ or CaSO₄ solution and scanned by DECT from 10 min to 27 h after mixing. The Hounsfield units (HUs) of sedimented DCBs on 40-keV monochromatic images were measured. Next, we mixed DCBs in 100, 10, 5 and 1 mM FeSO₄ solutions, and scanned these solutions from 15 to 120 min after mixing using a 3 T MR scanner. The signal-noise ratios (SNRs) of sedimented DCBs on T1-GRE were measured. Venous blood was scanned to compare with DCBs.

RESULTS

The CT values of DCBs in FeSO₄ and CaCl₂ solutions gradually increased, and were 113.3 and 43.1 HU at 27 h, respectively; that of blood was 17.8 HU. The SNR of DCB in 1 mM FeSO₄ solution increased and achieved equilibrium at 120 min, and was 120.5 and higher than in the other FeSO₄ solutions. The SNR of blood was 49.7.

CONCLUSION

Optimally Fe²⁺-loaded DCBs can be discriminated from venous blood on 40-keV monochromatic images from DECT and T1-GRE.