Advances in Biomaterials and Technologies for Vascular Embolization

A multicenter prospective study evaluating use of EmboCube™ Embolization Gelatin alone or in combination with other embolic agents to control bleeding

BACKGROUND

Embolization is a vital endovascular procedure that can be used to quickly achieve hemostasis in patients experiencing uncontrolled bleeding. This study was conducted to describe real-world outcomes following embolization with a pre-cut absorbable gelatin sponge to control bleeding.

METHODS

This prospective study was conducted across five hospitals in Australia and France. Inclusion criteria included adults ≥ 18 years who required embolization with EmboCube™ Embolization Gelatin for bleeding. Primary performance and safety endpoints were the proportion of patients that achieved clinical success (i.e., cessation of bleeding post-embolization, the absence of rebleeding at the treated site requiring reintervention within 24 h), and the absence of unanticipated serious adverse device effects within 24 h of the initial embolization, respectively. Secondary endpoints included technical success and serious device- and/or procedure-related adverse events 28 days post-initial embolization.

RESULTS

A total of 101 patients (54 males) were enrolled and treated. Sixty-six patients were treated with EmboCube only, 35 patients were treated with an additional embolic to control bleeding. Technical and clinical success rates were 100% and 99%, respectively. No patient experienced an unanticipated serious event related to the embolic. The mean time to hemostasis was 3.4 (± 3.96) minutes. Of the 90 patients that completed 28 days of follow-up, 4 (4.4%) experienced an adverse event (access site hematoma, n = 2; ischemic colitis, n = 1, peritonitis, n = 1).

CONCLUSION

EmboCube is safe and effective for control of acute and sub-acute arterial bleeding, alone or in combination with other embolic agents, when rapid hemostasis is required.

TRIAL REGISTRATION

Clinicaltrials.gov. Registered 23 March 2022, https://clinicaltrials.gov/study/NCT05307783 .

Vascular embolic nanobiomaterials for efficient tumor treatment

Embolization is a minimally invasive cancer treatment method. Embolization involves artificially blocking blood flow using an embolic agent to block abnormal blood vessels that supply nutrients or oxygen to a specific lesion, thereby killing the lesion, inhibiting its growth, and stopping bleeding. Currently, polyvinyl alcohol (PVA) and gelatin are the most popular embolic agents. These substances are available in various sizes and shapes that physically obstruct blood flow to cause vascular embolization. They are commonly used due to their ease of use and low cost. However, they can cause side-effect such as bleeding and potential complications related to catheter- and insertion-related complications. Recently, nanobiomaterials have been explored as embolization agents with high biocompatibility, such as liquid metals, and can be used with autologous blood. In this review, we cover the types of embolic agents currently used in cancer treatment and focus on those with fewer adverse effects and minimal vascular damage, followed by discussions on new embolic agents under development. Additionally, we explore potential future research directions for developing better embolic agents.

Real-world clinical experience with Obsidio Conformable Embolic

BACKGROUND

Obsidio Conformable Embolic (Obsidio) is a ready-made hydrogel with unique shear-thinning properties, used for occlusion of blood flow to control bleeding or hemorrhage in the peripheral vasculature and embolization of hypervascular tumors. While pre-clinical and clinical data have demonstrated successful embolizations using Obsidio, clinical experience overall is still limited, prompting a multi-institutional field assessment survey to collect additional data on the clinical utility and procedural details from a variety of Obsidio users. The field survey collected data from 131 embolization procedures performed using Obsidio between May and November 2023 at 27 institutions within the United States. Data collection included embolization site, vessel size, any adjunctive embolics used. The primary objective of the survey was to evaluate technical success, defined as complete embolization of the target vasculature immediately following the index procedure, as confirmed by angiography.

RESULTS

Of the 131 embolization procedures performed, 69% (n = 90) were for hemorrhage control, 15% (n = 19) were for hypervascular tumors, and 17% (n = 22) were for other indications. Embolization of the gastroduodenal artery was the most common indication (n = 19/131; 15%). A single syringe (1 mL) or less of Obsidio was used for most cases (93%). In 33/131 cases (25%), Obsidio was combined with other embolization devices including coils (n = 25; 19%), particle-based embolics (n = 6; 4.6%), or plugs (n = 2; 1.5%). Technical success was achieved in 100% of Obsidio embolization cases (131/131 procedures).

CONCLUSION

Initial clinical experience demonstrated successful embolization of end-organ bleeds and hypervascular tumors utilizing Obsidio, thus making it an effective embolic agent alone or in conjunction with other embolic devices.

Endovascular Treatment of Common Iliac Aneurysm After Aortobifemoral Bypass: Banana Technique and Shape Memory Polymer Plug Embolization

Objective: This case report aims to present a new endovascular technique for arterial embolization using a relatively recently developed endovascular device, Shape Memory Polymer (SMP) Embolization Plug (IMPEDE, Shape Memory Medical). Methods: A 66-year-old man presented an asymptomatic common iliac aneurysm with a maximun diameter of 4.4 cm and a previous aorto-bifemoral bypass. Results: An embolization of the common iliac artery aneurysm with 5 units of IMPEDE-FX Rapid Fill (12 mm, Shape Memory Medical) and revascularization from external iliac artery to internal iliac artery through a banana technique with an auto-expandable covered stent (Viabahn 10 × 100 mm, Gore) was performed. Conclusion: The experience obtained after the use of this device has allowed us to increase the therapeutic arsenal for high volume aneurysm embolization.

Covalently reactive microparticles imbibe blood to form fortified clots for rapid hemostasis and prevention of rebleeding

Owing to the inherently gradual nature of coagulation, the body fails in covalently crosslinking to stabilize clots rapidly, even with the aid of topical hemostats, thus inducing hemostatic failure and potential rebleeding. Although recently developed adhesives confer sealing bleeding sites independently of coagulation, interfacial blood hampers their adhesion and practical applications. Here, we report a covalently reactive hemostat based on blood-imbibing and -crosslinking microparticles. Once contacting blood, the microparticles automatically mix with blood via imbibition and covalently crosslink with blood proteins and the tissue matrix before natural coagulation operates, rapidly forming a fortified clot with enhanced mechanical strength and tissue adhesion. In contrast to commercial hemostats, the microparticles achieve rapid hemostasis (within 30 seconds) and less blood loss (approximately 35 mg and 1 g in the rat and coagulopathic pig models, respectively), while effectively preventing blood-pressure-elevation-induced rebleeding in a rabbit model. This work advances the development and clinical translation of hemostats for rapid hemostasis and rebleeding prevention.

Tumor Microenvironment Triggered In Situ Coagulation of Supramolecularly Engineered Platelets for Precise Tumor Embolization

Although embolization therapy has demonstrated success in impeding tumor growth, concerns persist regarding potential tumor recurrence and inadvertent embolization of non-target tissues. In this study, drawing inspiration from the natural targeting and coagulation process of platelets in injured blood vessels, platelets are engineered by integrating acid-sensitive, morphology-transformable nanoparticles onto their surface through supramolecular conjugation (PLT-NP). The nanoparticles are constructed through the self-assembly of a β-amyloid derived peptide (FFVLK) terminally functionalized with Fmoc, hexahistidine (His6), and a polyethylene glycol (PEG)-functionalized cyclodextrin (CD). The supramolecularly engineered platelets actively accumulate in the tumor tissue upon inducing a tumor blood vessel injury through tumor resection. In response to the local acidic microenvironment, the nanoparticles undergo a morphological transformation into nanofibers via spontaneous assembly of FFLVK into fibril structures through hydrogen bonding and β-sheet interactions, to artificially enhance the coagulation and aggregation of platelets, causing occlusion of tumor blood vessels. The supramolecularly engineered platelets efficiently embolize tumor blood vessels in a specific manner, effectively suppressing tumor growth, metastasis, and recurrence, thus offering a promising paradigm for combating cancer.

Advanced targeted microsphere embolization for arteriovenous malformations: state-of-the-art and future directions

BACKGROUND

Arteriovenous malformations (AVMs) present a significant therapeutic challenge, as current treatment modalities frequently fail to achieve complete and rapid obliteration and are associated with substantial morbidity in both the short and long term. This underscores the critical need for innovative therapeutic strategies that enable efficient AVM obliteration while minimizing patient risk. The current review aims to comprehensively assess the role of ATME in AVM management, examining its clinical efficacy, associated risks and benefits, and the economic and ethical implications to provide valuable foundation for future studies and guiding development in treatment strategies for AVMs.

RESULTS

Advanced targeted microsphere embolization (ATME) has emerged as a promising therapeutic option, initially developed for the localized treatment of AVMs and unresectable tumors, including liver cancer. By providing targeted delivery, ATME offers potential advantages over conventional approaches in achieving effective local control.

CONCLUSIONS

ATME are safe and effective for vascular disease and cancer. Although evidence for microspheres in AVMs is scarce, results are promising. Future research could refine eligibility criteria, evaluate treatment techniques, and optimize ATME.

A Single Institution Experience with a Shear-Thinning Conformable Embolic for Endovascular Embolization

PURPOSE

To assess the safety and efficacy of Obsidio™ conformable embolic (CE) for embolization in the peripheral vasculature.

MATERIALS AND METHODS

A retrospective review of the first 21 patients treated with CE was performed. Eighteen (85.7%) patients were male, and median age was 61.5 years (range, 12-89 years). Technical success was defined as stasis as assessed by a static contrast column for at least 5 heartbeats on post-embolization angiography. For procedures of peripheral vascular hemorrhage, clinical success was defined as hemorrhage resolution without reintervention within 30-day follow-up.

RESULTS

Indications for embolization were peripheral arterial hemorrhage (n = 13), preoperative tumor embolization (n = 4), preoperative embolization of renal cell carcinoma prior to cryoablation (n = 2), redistribution of flow prior to Yttrium-90 radioembolization to prevent nontarget radiation delivery (n = 1), and parastomal variceal embolization (n = 1). Embolization was performed via 2.4 or 2.8 French microcatheters flushed with saline prior to embolization. Most procedures (20/21) utilized < 1 cc of embolic, with the quantity used ranging between 0.1 and 1.4 cc. The amount of embolic injected was determined by the embolization endpoint, i.e., filling of the vessel intended for embolization. CE was used in combination with coils placed prior to CE in 4 procedures. Follow-up was a median of 57 days (range 0-244 days). Complete stasis was achieved in 100% (n = 21/21) of procedures. There were no post-procedure adverse events or rebleeding.

CONCLUSION

CE resulted in reliable vessel occlusion with no cases of rebleeding or reintervention and with no procedure-related adverse events in this series.

LEVEL OF EVIDENCE

Level 4, Case Series.

Recurrence of Cerebral Arteriovenous Malformation Following Complete Obliteration Through Endovascular Embolization

Arteriovenous malformation (AVM) recurrence after embolization was rarely reported. This study aimed to explore the potential risk factors of recurrence in angiographically obliterated AVMs treated with endovascular embolization. This study reviewed AVMs treated with embolization only in a prospective multicenter registry from August 2011 to December 2021, and ultimately included 92 AVMs who had achieved angiographic obliteration. Recurrence was assessed by follow-up digital subtraction angiography (DSA) or magnetic resonance imaging (MRI). Hazard ratios (HRs) with 95% confidence intervals were calculated using Cox proportional hazards regression models. Nineteen AVMs exhibited recurrence on follow-up imaging. The recurrence rates after complete obliteration at 6 months, 1 year, and 2 years were 4.35%, 9.78%, and 13.0%, respectively. Multivariate Cox regression analysis identified diffuse nidus (HR 3.208, 95% CI 1.030-9.997, p=0.044) as an independent risk factor for recurrence. Kaplan-Meier analysis confirmed a higher cumulative risk of recurrence with diffuse nidus (log-rank, p=0.016). Further, in the exploratory analysis of the effect of embolization timing after AVM rupture on recurrence after the complete obliteration, embolization within 7 days of the hemorrhage was found as an independent risk factor (HR 4.797, 95% CI 1.379-16.689, p=0.014). Kaplan-Meier analysis confirmed that embolization within 7 days of the hemorrhage was associated with a higher cumulative risk of recurrence in ruptured AVMs (log-rank, p<0.0001). This study highlights the significance of diffuse nidus as an independent risk factor for recurrence after complete embolization of AVMs. In addition, we identified a potential recurrent risk associated with early embolization in ruptured AVMs.

Coronary recanalization following spring coil occlusion: A case report and literature review

RATIONALE

Coronary artery perforation (CAP) is one of the most serious complications of percutaneous coronary intervention. Coronary arteriovenous fistula is a considerably rare type of congenital CAP. They are usually difficult to distinguish.

PATIENT CONCERNS

A male patient developed coronary artery perforation during percutaneous coronary intervention. As balloon occlusion was ineffective, a decision was made to implant a spring coil and bypass the occluded segment. However, the placement of spring coils restored patency in the occluded distal segment of the right coronary artery (RCA).

DIAGNOSES

Coronary computed tomography angiography is an auxiliary tool and Digital Subtraction Angiography(DSA) is the gold standard for the diagnosis.

INTERVENTIONS

Surgery and implant a spring coil are the main treatment methods.

OUTCOMES

The patient's RCA regained its blood supply. Coronary artery recanalization arteries occurred after spring coil placement. Combined with the imaging presentation, we finally determined that he was coronary-right ventricular fistula.

LESSONS

Although congenital CAPs are rare, appropriate detection and timely confirmation by coronary angiography are important for determining their subsequent management. Congenital coronary arteriovenous fistulae may be considered when coronary artery perforation during percutaneous coronary intervention, balloon blockade is ineffective and the patient's vital signs are stable.

Controllable Preparation and Performances of Monodisperse Genipin-Cross-Linked Gelatin-Chitosan Composite Embolic Microspheres

The controllable fabrication and performances of monodisperse genipin-cross-linked gelatin-chitosan composite (GGC) embolic microspheres with both uniform sizes and adjustable characteristics of elasticity and degradation are reported for the first time. Monodisperse emulsion droplets are fabricated as templates by using gelatin and chitosan aqueous solution as the disperse phase in a microfluidic device, and the chemical cross-linking of gelatin and chitosan inside droplet templates is achieved with genipin that transfers from the collection bath into the droplets. The sizes of droplet templates and the resultant GGC microspheres can be flexibly controlled and predicted by adjusting the fluid flow rates and the device dimensions. The elastic property of GGC microspheres can be flexibly regulated by adjusting the molar ratio of gelatin/chitosan in the disperse phase. The in vitro degradation-caused dynamic volume shrinkage of GGC microspheres can be flexibly regulated by adjusting the molar ratio of gelatin/chitosan, the chitosan deacetylation degree, and the enzyme concentration in degradation solution. Based on the Box-Behnken design-response surface method, a second-order equation is developed for the first time to predict the in vitro degradation-caused dynamic volume shrinkage ratios of microspheres prepared with different molar ratios of gelatin/chitosan and different chitosan deacetylation degrees in degradation solutions with different enzyme concentrations. The fabricated GGC microspheres show good repeatable embolization performances in an in vitro embolization chip system. The results of this study provide valuable guidance for controllable fabrication of degradable microspheres with both uniform sizes and on-demand elastic and degradation characteristics for efficient application in embolization therapy.

Uterine Artery Embolization: A Growing Pillar of Gynecological Intervention

Uterine Artery Embolization (UAE) is a minimally invasive procedure that has emerged as a transformative option for managing uterine leiomyomas (fibroids), postpartum hemorrhage, and other gynecological conditions. While traditional surgical interventions like hysterectomy and myomectomy remain standard, UAE offers a safer alternative for patients seeking uterine preservation or fertility maintenance. This article examines the efficacy, innovations, and challenges of UAE, with a focus on its expanding applications and implications for patient care. Existing research highlights high success rates of UAE, achieving significant symptom relief in over 90% of cases by occluding uterine arterial blood supply with embolic agents to induce localized ischemia and fibroid necrosis. Innovations in embolic materials, such as hydrophobic injectable liquids, and procedural techniques like transradial access have enhanced safety, reduced complications, and improved patient outcomes. The effectiveness of UAE in treating rarer conditions, including uterine arteriovenous malformations and adenomyosis, demonstrates its versatility. However, questions remain about its long-term reproductive impact, especially concerning fertility outcomes and pregnancy rates, as conflicting data suggest potential risks. This critical review addresses these gaps by synthesizing existing studies to assess comparative efficacy of UAE against surgical options, its safety profile, and its role in advancing minimally invasive gynecology. By exploring both well-established and emerging applications, this article underscores the importance of UAE in reducing morbidity, improving quality of life, and preserving reproductive potential. Further research is essential to refine patient selection criteria, optimize techniques, and better understand the long-term outcomes of the procedure, ensuring UAE continues to evolve as a valuable minimally invasive option within modern gynecological care.

Advancements in Nanomedicine for the Diagnosis and Treatment of Kidney Stones

Kidney stones constitute a common condition impacting the urinary system. In clinical diagnosis and management, traditional surgical interventions and pharmacological treatments are primarily utilized; however, these methods possess inherent limitations. Presently, the field of nanomedicine is undergoing significant advancements. The application of nanomaterials in biosensors enables the accurate assessment of urinary ion composition. Furthermore, contrast agents developed from these materials can improve the signal-to-noise ratio and enhance image clarity. By mitigating oxidative stress-induced cellular damage, nanomaterials can inhibit the formation of kidney stones and enhance the efficacy of drug delivery as effective carriers. Additionally, by modifying the physical and chemical properties of bacteria, nanomaterials can effectively eliminate bacterial presence, thereby preventing severe complications. This review explores the advancements in nanomaterials technology related to the early detection of risk factors, clinical diagnosis, and treatment of kidney stones and their associated complications.

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.

In Vivo Feasibility of Arterial Embolization with a New Permanent Agar-agar-Based Agent

PURPOSE

Evaluate the safety and efficacy of an eco-friendly permanent agar-agar-based embolization agent (ABEA) (EmboBio®) for intra-arterial use.

MATERIALS AND METHODS

Six pigs embolized with one ABEA torpedo (6 lower polar renal and 6 lumbar arteries) and one coil (6 lower polar renal and 6 lumbar arteries). Technical success was defined as a complete occlusion with no residual flow in DSA. Short-term endpoints included safety (non-targeted embolization), ease of use (embolization preparation time, occlusion time), and DSA controls at day 7, month 1, and month 3. Tissue reaction was assessed via [18F]-FDG PET/CT at month 2 and histological study at month 3.

RESULTS

ABEA torpedoes achieved immediate and persistent occlusion at month 3 for all kidney and lumbar embolizations (n = 12/12). Control coils had technical success for 12/12, with a persistent occlusion at month 3 for 2/12. No off-target embolization occurred. ABEA torpedoes demonstrate faster occlusion (ABEA: 6 ± 4 s; coils: 427 ± 469 s; p = 0.0022, n = 12) and preparation times (ABEA: 96.9 1 ± 23 s; coils: 150.33 ± 58 s; p = 0.0432, n = 12) after device placement than coil. No significant difference in inflammation between ABEA and coil groups at month 2 (ABEA: 3.35e-6 ± 1.7e-6%ID/mm3; coils: 2.24e-6 ± 8.5e-7%ID/mm3; p = 0.5) on PET imaging. These results were confirmed by histological analysis at month 3.

CONCLUSION

Permanent dry foam torpedo comprising agar-agar is effective for arterial embolization. In animal model, one ABEA torpedo demonstrates a faster and more persistent occlusion than one fiber coil.

LEVELS OF EVIDENCE

Not applicable.

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.

Sticky Science: Using Complex Coacervate Adhesives for Biomedical Applications

Tissue adhesives are used for various medical applications, including wound closure, bleeding control, and bone healing. Currently available options often show weak adhesion or cause adverse effects. Recently, there has been an increasing interest in complex coacervates as medical adhesives. Complex coacervates are formed by mixing oppositely charged macromolecules that associate and undergo liquid-liquid phase separation, in which the dense bottom phase is the complex coacervate. Complex coacervates are strong and often biocompatible, and show strong underwater adhesion. The properties of the resulting materials are tunable by intrinsic factors such as polymer chemistry, molecular weight, charge density, and topology of the macromolecules, as well as extrinsic factors such as temperature, pH, and salt concentration. Therefore, complex coacervates are interesting new candidates for medical adhesives. In this review, it is described how complex coacervates form and how different factors influence their behavior. Next, an overview of recent studies on complex coacervates in the context of medical adhesives is presented. The application of complex coacervates as hemostatic or embolic agents, skin or bone repair adhesives, and soft tissue sealants is discussed. Lastly, additional possibilities for utilizing these materials in the future are discussed.

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.

Glue and Ethanol Mixture for Aneurysm Endovascular Treatment: Animal Lab Study, Imaging, and Histopathological Findings

Background: This study aims to investigate the degree of penetration, permanence of occlusion, and vascular changes induced by a newly modified mixture of n-butyl cyanoacrylate (Glubran 2®), ethanol, and Lipidol® (GEL) in the endovascular treatment of experimental aneurysms induced in swine. Methods: Bilateral pouch aneurysms were created in the wall of the internal carotid artery in eighteen pigs. The sixteen aneurysms were treated with a new mixture of GEL with different component proportions. Angiograms were obtained at the time of treatment and at 1, 4, and 16 weeks after treatment. According to the scheduled experimental design, subjects were sacrificed at the time of treatment and 7, 30, and 90 days after the embolization of experimentally induced aneurysms. The internal carotid artery and aneurysms were removed en bloc and sampled for histopathologic study. Results: The mixture induced complete and stable occlusion without recanalization in all experimentally induced aneurysms throughout the study period. Histopathological studies showed focal angionecrosis and acute inflammatory reactions from 7 dpi, followed by chronic inflammation and vessel wall thickening. Conclusions: The GEL mixture may be useful in future clinical applications for the embolization of arteriovenous malformations, the control of acute bleeding, and the isolation of aneurysms due to its very short polymerization time and minimal adhesion to the microcatheter.

Heterogeneous multiple soft millirobots in three-dimensional lumens

Miniature soft robots offer opportunities for safe and physically adaptive medical interventions in hard-to-reach regions. Deploying multiple robots could further enhance the efficacy and multifunctionality of these operations. However, multirobot deployment in physiologically relevant three-dimensional (3D) tubular structures is limited by the lack of effective mechanisms for independent control of miniature magnetic soft robots. This work presents a framework leveraging the shape-adaptive robotic design and heterogeneous resistance from robot-lumen interactions to enable magnetic multirobot control. We first compute influence and actuation regions to quantify robot movement. Subsequently, a path planning algorithm generates the trajectory of a permanent magnet for multirobot navigation in 3D lumens. Last, robots are controlled individually in multilayer lumen networks under medical imaging. Demonstrations of multilocation cargo delivery and flow diversion manifest their potential to enhance biomedical functions. This framework offers a solution to multirobot actuation benefiting applications across different miniature robotic devices in complex environments.

A novel conformable embolic for selective transarterial embolization of acute hemorrhages: a technical note

BACKGROUND

Obsidio conformable embolic (OCE, Boston Scientific, MA) is a novel, radiopaque and conformable embolic. The purpose of this report is to describe its use for treatment of acute intra-abdominal hemorrhages.

METHODS AND RESULTS

Three patients presented with acute hemorrhage and were treated with OCE, including post-paracentesis hemorrhage, penetrating trauma to the liver, and blunt trauma in the spleen. All cases were performed under moderate sedation, with hemostasis achieved by end of procedure using less than 1 vial of OCE (0.2-0.4 ml). No severe adverse events occurred. None required repeated treatment.

SHORT CONCLUSION

OCE is a safe and effective embolic agent for treatment of intra-abdominal or visceral hemorrhage. Future studies with larger sample sizes and longer follow-up are warranted.

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.

Iodinated Cyanoacrylate-Based Novel Liquid Embolic Compositions with Inherent Radiopacity for Endovascular Embolization

Endovascular embolization is a promising therapeutic approach broadening its application area due to its minimal invasiveness and short operation time, wherein lesional blood vessels are occluded with liquid embolic agents under X-ray imaging guidance. Histoacryl and its composition with Lipiodol are one of the most widely used liquid embolic agents, however, Histoacryl has critical limitations, such as lack of innate X-ray visibility and strong adhesion to microcatheter. In this study, three different iodinated cyanoacrylates are newly synthesized as alternatives to Histoacryl and employed to develop liquid embolic compositions. Among them, 4-iodobutyl 2-cyanoacrylate (IBCA) is most preferable with high iodine content (730 mgI mL-1) and fast polymerization. The IBCA-based embolic compositions containing ethyl oleate and acetic acid showed moderate viscosity and reduced catheter adhesiveness (≈0.80 N), and their polymerization time is freely controllable from 2 to 15 s. In the embolization test with rabbit models, the renal artery is successfully occluded by IBCA-based embolic compositions without vascular recanalization or nontarget embolization for 4 w. Their embolic effect is further evaluated using swine models, demonstrating the practical applicability in the clinic. In conclusion, IBCA and its compositions are determined to have great potential as novel liquid embolic agents.

Retrospective clinical study on the efficacy and complications of interventional embolization in the treatment of scalp arteriovenous fistula

Introduction

Scalp arteriovenous fistula (AVF) is a rare and intricate vascular anomaly characterized by a direct connection between an artery and a vein, without an intervening capillary system. This anomaly can induce significant local hemodynamic changes and is associated with various complications, such as pain, a pulsatile mass, increasing swelling, and venous hypertension skin ulcerations which may be non-healing. This study aimed to evaluate the efficacy and safety of interventional embolization treatments for scalp AVF at Shandong Provincial Hospital.

Methods

This retrospective clinical analysis assessed 21 patients who underwent interventional embolization between 2018 and 2024. Patients included were those treated in the vascular surgery department at Shandong Provincial Hospital, who had comprehensive medical records and follow-up data. Treatment methods, outcomes, and complications were thoroughly analyzed through patient medical records.

Results

Among the patients studied, direct puncture was the most prevalent treatment method, employed in 42.86% (9/21) of cases, followed by various combinations of arterial, venous, and direct approaches. Ethanol, used in 85.71% (18/21) of the cases, demonstrated its broad efficacy and application in clinical settings. Immediate imaging post-treatment confirmed a cure rate of 85.71% (18/21). The main postoperative complications included swelling, with some patients also experiencing nodules, scabbing, or hair loss.

Conclusion

Interventional embolization has proven to be a safe and effective method for managing scalp AVF, significantly minimizing complications. Future research should focus on further optimizing these treatment methods to enhance efficacy and improve patient quality of life.

Isolation and focal treatment of brain aneurysms using interfacial fluid trapping

Current approaches for localized intravascular treatments rely on using solid implants, such as metallic coils for embolizing aneurysms, or on direct injection of a therapeutic agent that can disperse from the required site of action. Here, we present a fluid-based strategy for localizing intravascular therapeutics that leverages surface tension and immiscible fluid interactions, to allow confined and focal treatment at brain aneurysm sites. We first show, computationally and experimentally, that an immiscible phase can be robustly positioned at the neck of human aneurysm models to seal and isolate the aneurysm's cavity for further treatment, including in wide-neck aneurysms. We then demonstrate localized delivery and confined treatment, by selective staining of cell nuclei within the aneurysm cavity as well as by hydrogel-based embolization in patient-specific aneurysm models. Altogether, our interfacial flow-driven strategy offers a potential approach for intravascular localized treatment of cardiovascular and other diseases.

Ethanol Embolization of Chest Wall Arteriovenous Malformations: Four-Year Findings

OBJECTIVES

To summarize the clinical characteristics and investigate the efficacy of ethanol embolotherapy in the treatment of chest well arteriovenous malformation (AVM). Treatment-associated complications were also explored.

MATERIALS AND METHODS

Between March 2017 and August 2021, 32 consecutive patients (mean age, 23.7 years; age range, 5-54 years) who underwent ethanol embolotherapy for chest well AVMs under general anesthesia were included in this study. Embolization was performed through a direct puncture, transarterial catheterization, or a combination of the 2 procedures. The mean follow-up duration after the last treatment was 18.0 months (range, 3-42 months). The degree of devascularization on follow-up (assessed using angiography or computed tomography), and the clinical signs and symptoms of AVMs were evaluated as the therapeutic outcomes. The major and minor complications associated with the procedures were recorded.

RESULTS

A total of 103 embolization procedures (mean, 3.2; range, 2-7) comprising 101 ethanol embolization and 2 coil embolizations were performed on 32 patients with chest wall AVMs. The AVM nidus was accessed through the transarterial approach alone in 4 patients, by direct puncture in 11, and a combined procedure in 17 patients. Overall, more than 80% of the procedures were performed using the combined approach. Complete AVM devascularization was achieved in 12 (37.5%) patients. Moreover, 76% to 99% AVM was achieved in 18 patients (56.3%), and 50% to 75% in 2 patients (6.3%). Bleeding, pain, heart failure, and cosmetic deformities were the indications for treatment. For 3 patients (3/32, 9.4%) who had bleeding, the treatment stopped the hemorrhage. Complete pain relief was reported in 8 patients (8/32, 25.0%), whereas complete relief from congestive heart failure post-embolization was observed in 5 of the 6 patients with congestive heart failure (5/6, 83.3%). Complete correction of cosmesis deformities after embolization was achieved in 10 patients (10/32, 31.3%). Two patients who underwent surgery to correct persistent deformity after embolization only showed insignificant improvement. In addition, 6 (18.8%) patients developed 13 complications including blister, necrosis, hemothorax, transient hemoglobinuria, and transient pulmonary artery hypertension.

CONCLUSIONS

Ethanol embolotherapy is a safe and effective procedure for chest well AVMs. Surgery is required for some patients with residual cosmesis deformity.

CLINICAL IMPACT

Currently, there is no standard treatment for chest well AVMs due to their rarity and high heterogeneity. The present study shows that thanol embolotherapy is a safe and clinically effective treatment procedure for the chest well AVMs. Transarterial embolization in combination with direct puncture embolization can reach the AVM nidus. Ethanol embolotherapy can achieve complete obliteration of the AVM nidus in the majority of patients. Surgery may still be needed to correct cosmetic deformity after embolization. The present study provides valuable evidence to inform clinical decision-making.

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.

Development of a Short-Term Embolic Agent Based on Cilastatin for Articular Microvessels

Background and Objectives: This study aimed to develop an embolic agent with short-term embolic effects using cilastatin as the basic material. Materials and Methods: The particle size distribution of 25 mg cilastatin-based short-term embolic agents was evaluated microscopically under three different mixing conditions. A total of thirty-six healthy male Sprague Dawley rats were divided into four groups. Each group of six rats was injected once into the tail artery with 0.4 mL each of (A) Cilastatin + D-Mannitol Mixture, (B) Iohexol, (C) Prepenem, and (D) embolization promoter (EGgel). Results: A visual inspection of the tail appearance of rats in each group was performed at 0, 3, 7, 15, and 21 days. At weeks 1 and 3, three rats per group were euthanized, and histopathological analyses were performed on the specimens obtained from each group. No significant differences were observed on day 7, but mild inflammation was observed in Group (D) on day 15. Histopathological inflammation scoring of tail central artery embolization was performed using a six-point scale (from 0 = absent to 5 = marked inflammation). Three groups were formed consisting of six male New Zealand white rabbits each: control, positive control, and test groups. The control group received an Iohexol injection (rabbits: 0.8 mL). The positive control and experimental groups were injected with prepenem and cilastatin/D-mannitol compound, respectively (0.8 mL), and vascular angiography was performed. The order of occlusion progression after embolization was as follows: test group, positive control group, and control group. Conclusions: We developed a cilastatin/D-mannitol compound that exhibits characteristics of short-term embolization by utilizing the pharmacokinetic properties of cilastatin and the crystalline material D-mannitol. We evaluated its particle size distribution microscopically, conducted histopathological evaluation including inflammation via animal experiments, and assessed the embolization effect.

Intravascular elimination of circulating tumor cells and cascaded embolization with multifunctional 3D tubular scaffolds

The primary tumor ("root") and circulating tumor cells (CTCs; "seeds") are vital factors in tumor progression. However, current treatment strategies mainly focus on inhibiting the tumor while ignoring CTCs, resulting in tumor metastasis. Here, we design a multifunctional 3D scaffold with interconnected macropores, excellent photothermal ability and perfect bioaffinity as a blood vessel implantable device. When implanted upstream of the primary tumor, the scaffold intercepts CTCs fleeing back to the primary tumor and then forms "micro-thrombi" to block the supply of nutrients and oxygen to the tumor for embolization therapy. The scaffold implanted downstream of the tumor efficiently captures and photothermally kills the CTCs that escape from the tumor, thereby preventing metastasis. Experiments using rabbits demonstrated excellent biosafety of this scaffold with 86% of the CTC scavenging rate, 99% of the tumor inhibition rate and 100% of CTC killing efficiency. The multifunctional 3D scaffold synergistically inhibits the "root" and eliminates the "seeds" of the tumor, demonstrating its potential for localized cancer therapy with few side effects and high antitumor efficacy.

Fusible and Radiopaque Microspheres for Embolization

In this work, fusible microspheres loaded with radiopaque agents as an embolic agent for transcatheter arterial embolization (TAE) are developed. A poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) multi-block copolymer basing polyurethane (PCEU) is synthesized and fabricated into blank microspheres (BMs). The microspheres are elastic in compression test. A clinical contrast agent lipiodol is encapsulated in the microspheres to receive fusible radiopaque microspheres (FRMs). The sizes of FRMs are uniform and range from 142.2 to 343.1 µm. The encapsulated lipiodol acts as the plasticizer to reduce the melting temperature point (Tm) of PECU microspheres, thus, leading to the fusion of microspheres to exhibit efficient embolization in vivo. The performance of FRMs is carried out on a rabbit ear embolization model. Serious ischemic necrosis is observed and the radiopacity of FRMs sustains much longer time than that of commercial contrast agent Loversol in vivo. The fusible and radiopaque microsphere is promising to be developed as an exciting embolic agent.

Renal embolization for trauma: a narrative review

Renal injuries commonly occur in association with blunt trauma, especially in the setting of motor vehicle accidents. Contrast-enhanced computed tomography is considered the gold-standard imaging modality to assess patients for renal injuries in the setting of blunt and penetrating trauma, and to help classify injuries based on the American Association for the Surgery of Trauma injury scoring scale. The management of renal trauma has evolved in the past several decades, with a notable shift towards a more conservative, nonoperative approach. Advancements in imaging and interventional radiological techniques have enabled diagnostic angiography with angiographic catheter-directed embolization to become a viable option, making it possible to avoid surgical interventions that pose an increased risk of nephrectomy. This review describes the current management of renal trauma, with an emphasis on renal artery embolization techniques.

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.

Rhein‐based Pickering emulsion for hepatocellular carcinoma: Shaping the metabolic signaling and immunoactivation in transarterial chemoembolization

The efficacy of transarterial chemoembolization (TACE) has been limited by insufficient embolization and a high incidence of tumor recurrence. Herein, we identified that aberrant metabolic reprogramming and immunosuppression contribute to TACE refractoriness and Rhein, as a potential glycolytic metabolism inhibitor and immunoactivation inducer, was optimized to sensitize tumors to TACE therapy. To achieve efficient embolization, we developed an oil‐in‐water lipiodol embolic emulsion by stabilizing the self‐assembled Rhein nanogel. The assembled Rhein exhibited a nanofiber network, and its integration enhanced the mechanical stability and viscoelasticity of the lipiodol embolic agent. With the synergistic advantages of solid and liquid embolic agents, this carrier‐free Pickering emulsion exhibits efficient embolization and sustained drug release in models of unilateral renal artery embolization, rabbit ear tumor embolization, rabbit orthotopic liver cancer, and rat orthotopic liver cancer. Compared to conventional three‐way catheter mixing methods, multimodal imaging corroborates a marked enhancement in local drug retention and tumor suppression. Importantly, the incorporation of Rhein‐mediated synergistic immunoembolization in this strategy achieved efficient embolization while robustly activating anti‐tumor immune responses, including inducing immunogenic cell death, dendritic cell activation, and major histocompatibility complex class I presentation to CD8+ T cells for tumor killing. Together, these findings reveal a novel strategy for the application of self‐assembled Rhein nanofiber‐stabilized lipiodol emulsion to control metabolic signaling and immunoactivation in TACE.

Tissue Ablation: Applications and Perspectives

Tissue ablation techniques have emerged as a critical component of modern medical practice and biomedical research, offering versatile solutions for treating various diseases and disorders. Percutaneous ablation is minimally invasive and offers numerous advantages over traditional surgery, such as shorter recovery times, reduced hospital stays, and decreased healthcare costs. Intra-procedural imaging during ablation also allows precise visualization of the treated tissue while minimizing injury to the surrounding normal tissues, reducing the risk of complications. Here, the mechanisms of tissue ablation and innovative energy delivery systems are explored, highlighting recent advancements that have reshaped the landscape of clinical practice. Current clinical challenges related to tissue ablation are also discussed, underlining unmet clinical needs for more advanced material-based approaches to improve the delivery of energy and pharmacology-based therapeutics.

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.

Erosion of embolization coil into the renal collecting system: Retrograde fragmentation of stone and coil via thulium laser lithotripsy

A 50-year-old female developed kidney stones on an eroded embolization coil 16 months after percutaneous nephrolithotomy (PCNL) related bleeding complications. Retrograde ureteroscopy and thulium laser lithotripsy was performed to fragment the exposed portion of the coil into clinically insignificant pieces. Thulium laser coil fragmentation remains a potential strategy to remove eroded coils and their associated kidney stones; however, recurrent stone formation on the coil stump may necessitate repeat intervention if this conservative approach is pursued over radical antegrade coil removal. This case highlights the importance of continued surveillance and multidisciplinary management in preventing and treating coil erosion after PCNL.

A Novel Coacervate Embolic Agent for Tumor Chemoembolization

Transcatheter arterial chemoembolization (TACE) has proven effective in blocking tumor-supplied arteries and delivering localized chemotherapeutic treatment to combat tumors. However, traditional embolic TACE agents exhibit certain limitations, including insufficient chemotherapeutic drug-loading and sustained-release capabilities, non-biodegradability, susceptibility to aggregation, and unstable mechanical properties. This study introduces a novel approach to address these shortcomings by utilizing a complex coacervate as a liquid embolic agent for tumor chemoembolization. By mixing oppositely charged quaternized chitosan (QCS) and gum arabic (GA), a QCS/GA polymer complex coacervate with shear-thinning property is obtained. Furthermore, the incorporation of the contrast agent Iohexol (I) and the chemotherapeutic doxorubicin (DOX) into the coacervate leads to the development of an X-ray-opaque QCS/GA/I/DOX coacervate embolic agent capable of carrying drugs. This innovative formulation effectively embolizes the renal arteries without recanalization. More importantly, the QCS/GA/I/DOX coacervate can successfully embolize the supplying arteries of the VX2 tumors in rabbit ear and liver. Coacervates can locally release DOX to enhance its therapeutic effects, resulting in excellent antitumor efficacy. This coacervate embolic agent exhibits substantial potential for tumor chemoembolization due to its shear-thinning performance, excellent drug-loading and sustained-release capabilities, good biocompatibility, thrombogenicity, biodegradability, safe and effective embolic performance, and user-friendly application.

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.

Embolization coils in treating postoperative bronchopleural fistula: a systematic review

Objective

This study aims to comprehensively evaluate embolization coils in treating postoperative bronchopleural fistula (BPF).

Methods

A systematic review based on PubMed, Embase, and The Cochrane Library studies was conducted. All cases receiving embolization coils in treating postoperative BPF were included. The primary outcome was the efficacy of embolization coils in achieving closure of postoperative BPF.

Results

20 patients from 9 studies were included in this systematic review. A median number of 3 (range: 1-10) embolization coils with sealants obtained a complete closure rate of 80% in patients with postoperative BPF with sizes ranging from 2 to 3.1 mm. Three patients with BPF over 3 mm and one with multiple organ failure failed this treatment. Two cases of coil migration were reported without causing respiratory failure or fistula recurrence.

Conclusion

Embolization coils might be considered a safe and effective bronchoscopic treatment for small postoperative BPF of less than 3 mm in size. More extensive and rigorous studies are needed to further evaluate and confirm the optimal use of embolization coils in the context of an alternative to surgical repair.

Novel radiopaque ethanol injection: physicochemical properties, animal experiments, and clinical application in vascular malformations

BACKGROUND

Despite the efficacy of absolute ethanol (EtOH), its radiolucency introduces several risks in interventional therapy for treating vascular malformations. This study aims to develop a novel radiopaque ethanol injection (REI) to address this issue.

METHODS

Iopromide is mixed with ethanol to achieve radiopacity and improve the physicochemical properties of the solution. Overall, 82 male New Zealand white rabbits are selected for in vivo radiopacity testing, peripheral vein sclerosis [animals were divided into the following 5 groups (n = 6): negative control (NC, saline, 0.250 ml/kg), positive control (EtOH, 0.250 ml/kg), low-dose REI (L-D REI, 0.125 ml/kg), moderate-dose REI (M-D REI, 0.250 ml/kg), and high-dose REI (H-D REI 0.375 ml/kg)], pharmacokinetic analyses (the blood sample was harvested before injection, 5 min, 10 min, 20 min, 40 min, 1 h, 2 h, 4 h, and 8 h after injection in peripheral vein sclerosis experiment), peripheral artery embolization [animals were divided into the following 5 groups (n = 3): NC (saline, 0.250 ml/kg), positive control (EtOH, 0.250 ml/kg), L-D REI (0.125 ml/kg), M-D REI (0.250 ml/kg), and H-D REI (0.375 ml/kg)], kidney transcatheter arterial embolization [animals were divided into the following 4 groups (n = 3): positive control (EtOH, 0.250 ml/kg), L-D REI (0.125 ml/kg), M-D REI (0.250 ml/kg), and H-D REI (0.375 ml/kg); each healthy kidney was injected with saline as negative control], and biosafety evaluations [animals were divided into the following 5 groups (n = 3): NC (0.250 ml/kg), high-dose EtOH (0.375 ml/kg), L-D REI (0.125 ml/kg), M-D REI (0.250 ml/kg), and H-D REI (0.375 ml/kg)]. Then, a prospective cohort study involving 6 patients with peripheral venous malformations (VMs) is performed to explore the clinical safety and effectiveness of REI. From Jun 1, 2023 to August 31, 2023, 6 patients [age: (33.3 ± 17.2) years] with lingual VMs received sclerotherapy of REI and 2-month follow-up. Adverse events and serious adverse events were evaluated, whereas the efficacy of REI was determined by both the traceability of the REI under DSA throughout the entire injection and the therapeutic effect 2 months after a single injection.

RESULTS

The REI contains 81.4% ethanol (v/v) and 111.3 mg/ml iodine, which can be traced throughout the injection in the animals and patients. The REI also exerts a similar effect as EtOH on peripheral venous sclerosis, peripheral arterial embolization, and renal embolization. Furthermore, the REI can be metabolized at a similar rate compared to EtOH and Ultravist® and did not cause injury to the animals' heart, liver, spleen, lungs, kidneys and brain. No REI-related adverse effects have occurred during sclerotherapy of VMs, and 4/6 patients (66.7%) have achieved complete response at follow-up.

CONCLUSION

In conclusion, REI is safe, exerts therapeutic effects, and compensates for the radiolucency of EtOH in treating VMs.

TRIAL REGISTRATION

The clinical trial was registered as No. ChiCTR2300071751 on May 24 2023.

Bioengineered Ionic Liquid for Catheter-Directed Tissue Ablation, Drug Delivery, and Embolization

Delivery of therapeutics to solid tumors with high bioavailability remains a challenge and is likely the main contributor to the ineffectiveness of immunotherapy and chemotherapy. Here, a catheter-directed ionic liquid embolic (ILE) is bioengineered to achieve durable vascular embolization, uniform tissue ablation, and drug delivery in non-survival and survival porcine models of embolization, outperforming the clinically used embolic agents. To simulate the clinical scenario, rabbit VX2 orthotopic liver tumors are treated showing successful trans-arterial delivery of Nivolumab and effective tumor ablation. Furthermore, similar results are also observed in human ex vivo tumor tissue as well as significant susceptibility of highly resistant patient-derived bacteria is seen to ILE, suggesting that ILE can prevent abscess formation in embolized tissue. ILE represents a new class of liquid embolic agents that can treat tumors, improve the delivery of therapeutics, prevent infectious complications, and potentially increase chemo- and immunotherapy response in solid tumors.

The biological response of pH-switch-based gold nanoparticle-composite polyamino acid embolic material

With continuous advances in medical technology, non-invasive embolization has emerged as a minimally invasive treatment, offering new possibilities in cancer therapy. Fluorescent labeling can achieve visualization of therapeutic agents in vivo, providing technical support for precise treatment. This paper introduces a novel in situ non-invasive embolization composite material, Au NPs@(mPEG-PLGTs), created through the electrostatic combination of L-cysteine-modified gold nanoparticles (Au NPs) and methoxy polyethylene glycol amine-poly[(L-glutamic acid)-(L-tyrosine)] (mPEG-PLGTs). Experiments were undertaken to confirm the biocompatibility, degradability, stability and performance of this tumor therapy. The research results demonstrated a reduction in tumor size as early as the fifth day after the initial injection, with a significant 90% shrinkage in tumor volume observed after a 20-day treatment cycle, successfully inhibiting tumor growth and exhibiting excellent anti-tumor effects. Utilizing near-infrared in vivo imaging, Au NPs@(mPEG-PLGTs) displayed effective fluorescence tracking within the bodies of nude BALB-c mice. This study provides a novel direction for the further development and innovation of in situ non-invasive embolization in the field, highlighting its potential for rapid, significant therapeutic effects with minimal invasiveness and enhanced safety.

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.

New insights into mechanisms and interventions of locoregional therapies for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is responsible for a significant number of cancer-related deaths worldwide and its incidence is increasing. Locoregional treatments, which are precision procedures guided by imaging to specifically target liver tumors, play a critical role in the management of a substantial portion of HCC cases. These therapies have become an essential element of the HCC treatment landscape, with transarterial chemoembolization (TACE) being the treatment of choice for patients with intermediate to advanced stages of the disease. Other locoregional therapies, like radiofrequency ablation, are highly effective for small, early-stage HCC. Nevertheless, the advent of targeted immunotherapy has challenged these established treatments. Tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) have shown remarkable efficacy in clinical settings. However, their specific uses and the development of resistance in subsequent treatments have led clinicians to reevaluate the future direction of HCC therapy. This review concentrates on the distinct features of both systemic and novel locoregional therapies. We investigate their effects on the tumor microenvironment at the molecular level and discuss how targeted immunotherapy can be effectively integrated with locoregional therapies. We also examine research findings from retrospective studies and randomized controlled trials on various combined treatment regimens, assessing their validity to determine the future evolution of locoregional therapies within the framework of personalized, comprehensive treatment.

Bioinspired Tumor Calcification-Guided Early Diagnosis and Eradication of Hepatocellular Carcinoma

Tumor calcification is found to be associated with the benign prognostic, and which shows considerable promise as a somewhat predictive index of the tumor response clinically. However, calcification is still a missing area in clinical cancer treatment. A specific strategy is proposed for inducing tumor calcification through the synergy of calcium peroxide (CaO2)-based microspheres and transcatheter arterial embolization for the treatment of hepatocellular carcinoma (HCC). The persistent calcium stress in situ specifically leads to powerful tumor calcioptosis, resulting in diffuse calcification and a high-density shadow on computed tomography that enables clear localization of the in vivo tumor site and partial delineation of tumor margins in an orthotopic HCC rabbit model. This osmotic calcification can facilitate tumor clinical diagnosis, which is of great significance in differentiating tumor response during early follow-up periods. Proteome and phosphoproteome analysis identify that calreticulin (CALR) is a crucial target protein involved in tumor calcioptosis. Further fluorescence molecular imaging analysis also indicates that CALR can be used as a prodromal marker of calcification to predict tumor response at an earlier stage in different preclinical rodent models. These findings suggest that upregulated CALR in association with tumor calcification, which may be broadly useful for quick visualization of tumor response.

Recent advances in nanomaterial-driven strategies for diagnosis and therapy of vascular anomalies

Nanotechnology has demonstrated immense potential in various fields, especially in biomedical field. Among these domains, the development of nanotechnology for diagnosing and treating vascular anomalies has garnered significant attention. Vascular anomalies refer to structural and functional anomalies within the vascular system, which can result in conditions such as vascular malformations and tumors. These anomalies can significantly impact the quality of life of patients and pose significant health concerns. Nanoscale contrast agents have been developed for targeted imaging of blood vessels, enabling more precise identification and characterization of vascular anomalies. These contrast agents can be designed to bind specifically to abnormal blood vessels, providing healthcare professionals with a clearer view of the affected areas. More importantly, nanotechnology also offers promising solutions for targeted therapeutic interventions. Nanoparticles can be engineered to deliver drugs directly to the site of vascular anomalies, maximizing therapeutic effects while minimizing side effects on healthy tissues. Meanwhile, by incorporating functional components into nanoparticles, such as photosensitizers, nanotechnology enables innovative treatment modalities such as photothermal therapy and photodynamic therapy. This review focuses on the applications and potential of nanotechnology in the imaging and therapy of vascular anomalies, as well as discusses the present challenges and future directions.

Thermoresponsive Gels with Embedded Starch Microspheres for Optimized Antibacterial and Hemostatic Properties

Apart from single hemostasis, antibacterial and other functionalities are also desirable for hemostatic materials to meet clinical needs. Cationic materials have attracted great interest for antibacterial/hemostatic applications, and it is still desirable to explore rational structure design to address the challenges in balanced hemostatic/antibacterial/biocompatible properties. In this work, a series of cationic microspheres (QMS) were prepared by the facile surface modification of microporous starch microspheres with a cationic tannic acid derivate, the coating contents of which were adopted for the first optimization of surface structure and property. Thermoresponsive gels with embedded QMS (F-QMS) were further prepared by mixing a neutral thermosensitive polymer and QMS for second structure/function optimization through different QMS and loading contents. In vitro and in vivo results confirmed that the coating content plays a crucial role in the hemostatic/antibacterial/biocompatible properties of QMS, but varied coating contents of QMS only lead to a classical imperfect performance of cationic materials. Inspiringly, the F-QMS-4 gel with an optimal loading content of QMS4 (with the highest coating content) achieved a superior balanced in vitro hemostatic/antibacterial/biocompatible properties, the mechanism of which was revealed as the second regulation of cell-material/protein-material interactions. Moreover, the optimal F-QMS-4 gel exhibited a high hemostatic performance in a femoral artery injury model accompanied by the easy on-demand removal for wound healing endowed by the thermoresponsive transformation. The present work offers a promising approach for the rational design and facile preparation of cationic materials with balanced hemostatic/antibacterial/biocompatible properties.