The histotoxicity of cyanoacrylates. A selective review

Natural Polymer-Polyphenol Bioadhesive Coacervate with Stable Wet Adhesion, Antibacterial Activity, and On-Demand Detachment

Medical adhesives are emerging as an important clinical tool as adjuvants for sutures and staples in wound closure and healing and in the achievement of hemostasis. However, clinical adhesives combining cytocompatibility, as well as strong and stable adhesion in physiological conditions, are still in demand. Herein, a mussel-inspired strategy is explored to produce adhesive coacervates using tannic acid (TA) and methacrylate pullulan (PUL-MA). TA|PUL-MA coacervates mainly comprise van der Waals forces and hydrophobic interactions. The methacrylic groups in the PUL backbone increase the number of interactions in the adhesives matrix, resulting in enhanced cohesion and adhesion strength (72.7 Jm-2), compared to the non-methacrylated coacervate. The adhesive properties are kept in physiologic-mimetic solutions (72.8 Jm-2) for 72 h. The photopolymerization of TA|PUL-MA enables the on-demand detachment of the adhesive. The poor cytocompatibility associated with the use of phenolic groups is here circumvented by mixing reactive oxygen species-degrading enzyme in the adhesive coacervate. This addition does not hamper the adhesive character of the materials, nor their anti-microbial or hemostatic properties. This affordable and straightforward methodology, together with the tailorable adhesivity even in wet environments, high cytocompatibility, and anti-bacterial activity, enables foresee TA|PUL-MA as a promising ready-to-use bioadhesive for biomedical applications.

Blocked-flow vs. free-flow cyanoacrylate glue embolization: Histological differences in an in vivo rabbit renal artery model

PURPOSE

The purpose of this in vivo animal study was to compare the acute histological effects on the arterial vessel wall of free-flow vs. blocked-flow embolization with metacryloxysulfolane-n‑butyl cyanoacrylate (MS-NBCA) in several concentrations.

MATERIALS AND METHODS

A total of 42 rabbit renal arteries were embolized using MS-NBCA mixed with ethiodized oil. The MS-NBCA concentration was 12.5%, 25%, or 50%. All mixtures were injected under both free-flow and blocked-flow conditions. The rabbits were euthanised 30 min after arterial embolization. Arterial-lumen distension, intimal inflammation and necrosis, peri‑arterial edema, and distality of MS-NBCA penetration were assessed histologically. Multivariable regression analyses were performed using a manual backward procedure, with linear, ordinal and logistic regression to search for factors associated with these outcomes RESULTS: Marked or severe dilatation was observed in 36 out of 42 arteries (86%) and marked or transmural intimal arteritis in all 42 arteries (42/42; 100%). Lumen dilatation caused focal vessel-wall flattening, which resulted in intimal necrosis. Multifocal necrosis extending from the intima to the media occurred in 23 out of 42 kidneys (55%) and peri‑arterial edema with multifocal vascular leakage in 19 out of 42 kidneys (45%). At multivariable analysis, blocked-flow MS-NBCA injection was associated with greater severity of vessel-wall lesions, including intimal arteritis (P = 0.003) and intimal necrosis (P = 0.014), compared to free-flow injection. Blocked-flow injection was also associated with peri‑arterial edema (P = 0.008) and greater distality of MS-NBCA penetration (P = 0.001).

CONCLUSION

Blocked-flow MS-NBCA injection during renal artery embolization is significantly associated with more acute arterial-wall damage and greater distality of glue penetration compared to free-flow injection in a rabbit model. These preliminary findings may have clinical implications, as blocked-flow injection is routinely used to treat specific vascular diseases or malformations in human.

899 serious adverse events including 13 deaths, 7 strokes, 211 thromboembolic events, and 482 immune reactions: The untold story of cyanoacrylate adhesive closure

OBJECTIVE

The aim was to retrieve and analyse the serious adverse events of venous occlusion systems used in cyanoacrylate adhesive closure (CAC) submitted to regulatory agencies.

METHODS

The Total Product Life Cycle (TPLC) database of the US Food and Drug Administration (FDA), the Database of Adverse Event Notifications (DAEN) of the Australian Therapeutic Goods Administration (TGA), and the Yellow Card database of the UK Medicines and Healthcare Products Regulatory Agency (MHRA) were reviewed. Three Freedom of Information (FOI) requests had to be submitted to the MHRA to obtain data.

RESULTS

The TPLC contained 899 reports which included 13 cases of death, 7 strokes, 211 thromboembolic events, and 482 immune reactions. The DAEN recorded three reportable adverse events, and the MHRA recorded seven adverse incidents including one death.

CONCLUSION

CAC is associated with serious adverse events including death. These events are under-reported in the medical literature and only sub-optimally reported to the regulatory agencies.

Selective Arterial Embolization of Ruptured Hepatocellular Carcinoma with N-Butyl Cyanoacrylate and Lipiodol: Safety, Efficacy, and Short-Term Outcomes

The rupture of hepatocellular carcinoma (rHCC) is uncommon but causes sudden life-threatening bleeding. Selective transarterial embolization (STAE) is an effective bleeding-control option. The optimal embolic agent is unknown, and data on the use of cyanoacrylate glue are lacking. The objective of this study was to report the outcomes of cyanoacrylate-lipiodol embolization for rHCC. We retrospectively reviewed the files of the 16 patients (14 males; mean age, 72 years) who underwent emergency cyanoacrylate-lipiodol STAE at a single center in 2012-2023 for spontaneous rHCC. All 16 patients had subcapsular HCC and abundant hemoperitoneum. The technical success rate was 94% (15/16). Day 30 mortality was 19%; the three patients who died had severe hemodynamic instability at admission; one death was due to rebleeding. Liver enzyme levels returned to baseline by day 30. No rebleeding was recorded during the median follow-up of 454 days in the 10 patients who were alive with available data after day 30. Larger prospective studies with the collection of longer-term outcomes are needed to assess our results supporting the safety and effectiveness of cyanoacrylate-lipiodol STAE for rHCC. Randomized trials comparing this mixture to other embolic agents should be performed.

Differences in Outflow Facility Between Angiographically Identified High- Versus Low-Flow Regions of the Conventional Outflow Pathways in Porcine Eyes

Purpose

To investigate differences in outflow facility between angiographically determined high- and low-flow segments of the conventional outflow pathway in porcine eyes.

Methods

Porcine anterior segments (n = 14) were mounted in a perfusion chamber and perfused using Dulbecco's phosphate buffered solution with glucose. Fluorescein angiography was performed to determine high- and low-flow regions of the conventional outflow pathways. The trabecular meshwork (TM) was occluded using cyanoacrylate glue, except for residual 5-mm TM areas that were either high or low flow at baseline, designating these eyes as "residual high-flow" or "residual low-flow" eyes. Subsequently, outflow was quantitatively reassessed and compared between residual high-flow and residual low-flow eyes followed by indocyanine green angiography.

Results

Fluorescein aqueous angiography demonstrated high-flow and low-flow regions. Baseline outflow facilities were 0.320 ± 0.08 and 0.328 ± 0.10 µL/min/mmHg (P = 0.676) in residual high-flow and residual low-flow eyes before TM occlusion, respectively. After partial trabecular meshwork occlusion, outflow facility decreased to 0.209 ± 0.07 µL/min/mmHg (-32.66% ± 19.53%) and 0.114 ± 0.08 µL/min/mmHg (-66.57% ± 23.08%) in residual high- and low-flow eyes (P = 0.035), respectively. There was a significant difference in the resulting IOP increase (P = 0.034).

Conclusions

Angiographically determined high- and low-flow regions in the conventional outflow pathways differ in their segmental outflow facility; thus, there is an uneven distribution of local outflow facility across different parts of the TM.

Injectable Click Fibroin Bioadhesive Derived from Spider Silk for Accelerating Wound Closure and Healing Bone Fracture

Wound closure is a critical step in postoperative wound recovery. Substantial advancements have been made in many different means of facilitating wound closure, including the use of tissue adhesives. Compared to conventional methods, such as suturing, tissue bioadhesives better accelerate wound closure. However, several existing tissue adhesives suffer from cytotoxicity, inadequate tissue adhesive strength, and high costs. In this study, a series of bioadhesives was produced using non-swellable spider silk-derived silk fibroin protein and an outer layer of swellable polyethylene glycol and tannic acid. The gelation time of the spider silk-derived silk fibroin protein bioadhesive is less than three minutes and thus can be used during rapid surgical wound closure. By adding polyethylene glycol (PEG) 2000 and tannic acid as co-crosslinking agents to the N-Hydroxysuccinimide (NHS), and 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) reaction, the adhesive strength of the bioadhesive became 2.5 times greater than that of conventional fibrin glue adhesives. Silk fibroin bioadhesives do not show significant cytotoxicity in vitro compared with other bioadhesives. In conclusion, silk fibroin bioadhesive is promising as a new medical tool for more effective and efficient surgical wound closure, particularly in bone fractures.

Comparison of Surgical Outcomes of Laparoscopic Glue and Laparoscopic Suture Hernioplasty in Pediatric Female Inguinal Hernia

This study aimed to report the surgical outcomes of laparoscopic glue hernioplasty (LGH) compared with conventional laparoscopic suture hernioplasty (LSH) in pediatric female inguinal hernia repair. We retrospectively analyzed 465 female pediatric patients who underwent laparoscopic inguinal hernia repair between January 2013 and December 2020. LGH and LSH were performed in 95 and 370 cases, respectively. Surgical outcomes (length of hospital stay, operative time, complications, and recurrences) were compared between the LGH and LSH groups. We found that the operation times for bilateral hernia repair were shorter in the LGH group (LGH: 35.5 ± 8.2 min, LSH: 45.2 ± 11.6 min; p < 0.001). No significant differences in complications or recurrences were observed between the two groups during the follow-up period. Our findings suggest that LGH is a feasible and easily applied surgical technique for the treatment of pediatric female inguinal hernia.

In Vivo Sol-Gel Reaction of Tantalum Alkoxide for Endovascular Embolization

Liquid embolic agents are considered the most promising for various embolization procedures because they enable deep penetration. For realizing effective procedures, the delivery of liquid embolic agents should be guided under X-ray imaging systems and the solidification time should be optimized for the specific indication. The biocompatibility of embolic agents is also crucial because they remain in the vessel after embolization. In this study, new biocompatible embolic agents based on tantalum ethoxide is synthesized. Tantalum alkoxide liquid embolics (TALE) possess the radiopacity for fluoroscopy and can control the penetration depth by modifying the sol-gel kinetics. Furthermore, TALE can serve as drug carriers for synergistic treatment. Using these excellent characteristics, it is demonstrated that TALE agents can be used in various situations including the transarterial chemoembolization of hepatocellular carcinoma and embolotherapy of massive bleeding from the femoral artery.

A chitosan hydrogel sealant with self-contractile characteristic: From rapid and long-term hemorrhage control to wound closure and repair

Emergent and long-term hemorrhage control is requisite and beneficial for reducing global mortality and postoperative complications (e.g., second bleeding and adverse tissue adhesion). Despite recent advance in injectable hydrogels for hemostasis, achieving rapid gelation, strong tissue-adhesive property and stable mechanical strength under fluid physiological environment is still challenging. Herein, we developed a novel chitosan hydrogel (CCS@gel) via dynamic Schiff base reaction and mussel-inspired catechol chemistry. The hydrogel possessed high gelation rate (<10 s), strong wet adhesiveness, excellent self-healing performance and biocompatibility. More importantly, the CCS@gel exhibited saline-induced contractile performance and mechanical enhancement, promoting its mechanical property in moist internal conditions. In vivo studies demonstrated its superior hemostatic efficacy for diverse anticoagulated visceral and carotid bleeding scenarios, compared to commercialized fibrin glue. The hydrogel-treated rats survived for 8 weeks with minimal inflammation and postoperative adhesion. These results revealed that the promising CCS@gel would be a facile, efficient and safe sealant for clinical hemorrhage control.

Relevant Biological Effects of Varicocele Embolization with N-Butyl Cyanoacrylate Glue on Semen Parameters in Infertile Men

Surgical treatment or varicocele embolization (VE) with sclerosing or mechanical embolic agents have been shown to improve the semen parameters of infertile men. The aim of this study was to evaluate the impact of VE using N-butyl cyanoacrylate (NBCA) glue on semen parameters in infertile men. From January 2014 to June 2018, infertile adult patients with stage 3 varicocele and an initial semen analysis showing at least one abnormal semen parameter, and who were successfully embolized with NBCA Glubran^®2 glue, were retrospectively recruited. The availability of a second semen analysis after VE was mandatory for patient inclusion. The primary endpoint was the change in total sperm number (TSN) after VE. The other parameters of interest were progressive and total sperm motilities (Smot) at 1 h (H1), sperm vitality (SV) and morphology (SMor). One hundred and two patients were included. Eight patients presented null TSN before and after VE. Among the remaining 94 patients, a significant improvement in the median TSN after VE was shown (31.79 × 10⁶/ejaculate [IQR: 11.10-127.40 × 10⁶/ejaculate] versus 62.24 × 10⁶/ejaculate [IQR: 17.90-201.60 × 10⁶/ejaculate], p = 0.0295). Significant improvement in TSN was found for the 60 oligo- or azoospermic patients (p = 0.0007), whereas no significant change was found for the 42 patients with normal initial TSN (p = 0.49). Other parameters, such as progressive and total SMot, SV and SMor, also significantly improved after VE (p = 0.0003, 0.0013, 0.0356 and 0.007, respectively). The use of NBCA glue as an embolic agent for VE in infertile men with stage 3 varicocele significantly improves the semen parameters.

Endovascular Use of Cyanoacrylate-Lipiodol Mixture for Peripheral Embolization: Properties, Techniques, Pitfalls, and Applications

Endovascular embolization agents are particles and fluids that can be released into the bloodstream through a catheter to mechanically and/or biologically occlude a target vessel, either temporarily or permanently. Vascular embolization agents are available as solids, liquids, and suspensions. Although liquid adhesives (glues) have been used as embolic agents for decades, experience with them for peripheral applications is generally limited. Cyanoacrylates are the main liquid adhesives used for endovascular interventions and have a major role in managing vascular abnormalities, bleeding, and many vascular diseases. They can only be injected as a mixture with ethiodized oil, which provides radiopacity and modulates the polymerization rate. This review describes the characteristics, properties, mechanisms of action, modalities of use, and indications of the cyanoacrylate-Lipiodol® combination for peripheral embolization.

Selective Arterial Embolization of Renal Angiomyolipomas with a N-Butyl Cyanoacrylate-Lipiodol Mixture: Efficacy, Safety, Short- and Mid-Term Outcomes

Selective arterial embolization (SAE) for renal angiomyolipoma (rAML) is effective to treat or prevent bleeding. We report our experience using a cyanoacrylate–Lipiodol mixture. We performed a single-center retrospective review of all rAMLs embolized with cyanoacrylate glue between July 2014 and June 2020. Demographics, tuberous sclerosis complex (TSC) status, clinical presentation, angiography features, and follow-up data were recorded. Pre- and post-procedure rAML sizes and volumes were estimated from computed tomography (CT) or magnetic resonance imaging (MRI) studies. Kidney function was assessed before and after the procedure. We identified 24 patients (22 females and 2 males, mean age 51 years) treated for 27 AMLs, either prophylactically (n = 20) or as an emergency (n = 4). Technical success was achieved for 25/27 AMLs; two patients, each with a single AML, required nephrectomy and repeated embolization, respectively. Major complications occurred in three patients and minor complications such as postembolization syndrome in 15 patients. AML volume reduction after embolization was 55.1% after a mean follow-up of 15 months (range, 1–72 months). Factors associated with greater volume reduction were a smaller percentage of fat (p = 0.001), larger initial rAML volume (p = 0.014), and longer follow-up (p = 0.0001). The mean creatinine level did not change after SAE. Embolization of rAMLs with a mixture of cyanoacrylate and Lipiodol is feasible, safe, and effective in significantly decreasing tumor volume.

Glue, Onyx, Squid or PHIL? Liquid Embolic Agents for the Embolization of Cerebral Arteriovenous Malformations and Dural Arteriovenous Fistulas

Background

Endovascular embolization is an effective treatment option for cerebral arteriovenous malformations (AVMs) and dural arteriovenous fistulas (DAVFs). A variety of liquid embolic agents have been and are currently used for embolization of AVMs and DAVFs. Knowledge of the special properties of the agent which is used is crucial for an effective and safe embolization procedure.

Material and Methods

This article describes the properties and indications of the liquid embolic agents which are currently available: cyanoacrylates (also called glues), and the copolymers Onyx, Squid and PHIL, as well as their respective subtypes.

Results

Cyanoacrylates were the predominantly used agents in the 1980s and 1990s. They are currently still used in specific situations, for example for the occlusion of macro-shunts, for the pressure cooker technique or in cases in which microcatheters are used that are not compatible with dimethyl-sulfoxide. The first broadly used copolymer-based embolic agent Onyx benefits from a large amount of available experience and data, which demonstrated its safety and efficacy in the treatment of cerebral vascular malformations, while its drawbacks include temporary loss of visibility during longer injections and artifacts in cross-sectional imaging. The more recently introduced agents Squid and PHIL aim to overcome these shortcomings and to improve the success rate of endovascular embolization. Novelties of these newer agents with potential advantages include extra-low viscosity versions, more stable visibility, and a lower degree of imaging artifacts.

Conclusion

All the available liquid embolic agents feature specific potential advantages and disadvantages over each other. The choice of the most appropriate embolic agent must be made based on the specific material characteristics of the agent, related to the specific anatomical characteristics of the target pathology.

Laser ablation of the pia mater for insertion of high-density microelectrode arrays in a translational sheep model

Objective. The safe insertion of high density intracortical electrode arrays has been a long-standing practical challenge for neural interface engineering and applications such as brain-computer interfaces (BCIs). However, the pia mater can be difficult to penetrate and causes deformation of underlying cortical tissue during insertion of high-density intracortical arrays. This can lead to neuron damage or failed insertions. The development of a method to ease insertion through the pia mater would represent a significant step toward inserting high density intracortical arrays.Approach. Here we describe a surgical procedure, inspired by laser corneal ablation, that can be used in translational models to thin the pia mater.Main results. We demonstrate that controlled pia removal with laser ablation over a small area of cortex allows for microelectrode arrays to be inserted into the cortex with less force, thus reducing deformation of underlying tissue during placement of the microelectrodes. This procedure allows for insertion of high-density electrode arrays and subsequent acute recordings of spiking neuron activity in sheep cortex. We also show histological and electrophysiological evidence that laser removal of the pia does not acutely affect neuronal viability in the region.Significance. Laser ablation of the pia reduces insertion forces of high-density arrays with minimal to no acute damage to cortical neurons. This approach suggests a promising new path for clinical BCI with high-density microelectrode arrays.

Multifaceted Design and Emerging Applications of Tissue Adhesives

Tissue adhesives can form appreciable adhesion with tissues and have found clinical use in a variety of medical settings such as wound closure, surgical sealants, regenerative medicine, and device attachment. The advantages of tissue adhesives include ease of implementation, rapid application, mitigation of tissue damage, and compatibility with minimally invasive procedures. The field of tissue adhesives is rapidly evolving, leading to tissue adhesives with superior mechanical properties and advanced functionality. Such adhesives enable new applications ranging from mobile health to cancer treatment. To provide guidelines for the rational design of tissue adhesives, here, existing strategies for tissue adhesives are synthesized into a multifaceted design, which comprises three design elements: the tissue, the adhesive surface, and the adhesive matrix. The mechanical, chemical, and biological considerations associated with each design element are reviewed. Throughout the report, the limitations of existing tissue adhesives and immediate opportunities for improvement are discussed. The recent progress of tissue adhesives in topical and implantable applications is highlighted, and then future directions toward next-generation tissue adhesives are outlined. The development of tissue adhesives will fuse disciplines and make broad impacts in engineering and medicine.

Engineering Hydrogel Adhesion for Biomedical Applications via Chemical Design of the Junction

Hydrogel adhesion inherently relies on engineering the contact surface at soft and hydrated interfaces. Upon contact, adhesion normally occurs through the formation of chemical or physical interactions between the disparate surfaces. The ability to form these adhesion junctions is challenging for hydrogels as the interfaces are wet and deformable and often contain low densities of functional groups. In this Review, we link the design of the binding chemistries or adhesion junctions, whether covalent, dynamic covalent, supramolecular, or physical, to the emergent adhesive properties of soft and hydrated interfaces. Wet adhesion is useful for bonding to or between tissues and implants for a range of biomedical applications. We highlight several recent and emerging adhesive hydrogels for use in biomedicine in the context of efficient junction design. The main focus is on engineering hydrogel adhesion through molecular design of the junctions to tailor the adhesion strength, reversibility, stability, and response to environmental stimuli.

Modified hyaluronic acid hydrogels with chemical groups that facilitate adhesion to host tissues enhance cartilage regeneration

Stable integration of hydrogel implants with host tissues is of critical importance to cartilage tissue engineering. Designing and fabricating hydrogels with high adhesive strength, stability and regeneration potential are major challenges to be overcome. This study fabricated injectable adhesive hyaluronic acid (HA) hydrogel modified by aldehyde groups and methacrylate (AHAMA) on the polysaccharide backbone with multiple anchoring mechanisms (amide bond through the dynamic Schiff base reaction, hydrogen bond and physical interpenetration). AHAMA hydrogel exhibited significantly improved durability and stability within a humid environment (at least 7 days), together with higher adhesive strength (43 KPa to skin and 52 KPa to glass), as compared to commercial fibrin glue (nearly 10 KPa) and HAMA hydrogel (nearly 20 KPa). The results showed that AHAMA hydrogel was biocompatible and could be easily and rapidly prepared in situ. In vitro cell culture experiments showed that AHAMA hydrogel could enhance proliferation (1.2-folds after 3 days) and migration (1.5-folds after 12 h) of bone marrow stem cells (BMSCs), as compared to cells cultured in a culture dish. Furthermore, in a rat osteochondral defect model, implanted AHAMA hydrogel significantly promoted integration between neo-cartilage and host tissues, and significantly improved cartilage regeneration (modified O'Driscoll histological scores of 16.0 ± 4.1 and 18.3 ± 4.6 after 4 and 12-weeks of post-implantation in AHAMA groups respectively, 12.0 ± 2.7 and 12.2 ± 2.8 respectively in HAMA groups, 9.8 ± 2.4 and 11.5 ± 2.1 respectively in untreated groups). Hence, AHAMA hydrogel is a promising adhesive biomaterial for clinical cartilage regeneration and other biomedical applications.

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Adhesive hydrogel composed of single natural polymer component.

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The single component enhance stable and easy to use in surgical operation of hydrogel.

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Adhesive hydrogel exhibited strong adhesive strength through multiple anchoring mechanisms.

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Adhesive hydrogel promoted integration between neo-cartilage and host tissues, drastically improved cartilage regeneration.

Histopathological Comparison of 2-Octyl Cyanoacrylate and Primary Suturing for Tongue Lacerations

OBJECTIVE

To enable tongue incisions to be repaired more easily, rapidly, and practically, particularly in pediatric patients by using 2-octyl cyanoacrylate (OCA) tissue adhesive.

METHODS

A single linear incision was made on the midline dorsal part of the tongue. Twenty-four rats were randomly divided into the four groups: Group 1 (n = 6), OCA healing at day 5; group 2 (n = 6), OCA healing at day 21; group 3 (n = 6), Vicryl healing at day 5; group 4 (n = 6), Vicryl healing at day 21. In groups 1 and 2, OCA was applied to the incision site. The incisions of the rats in groups 3 and 4 were closed using Vicryl sutures. Histopathological examination was compared between and within the groups at day 5 and 21.

RESULTS

The operation duration was significantly shorter with OCA than with Vicryl sutures(P < 0.001). Regarding the histopathological results, there were no differences between group 1 and group 3 in epithelial regeneration, inflammation, fibroblastic activity, edema, presence of giant cells, fibrin deposition, ulceration, abscess formation, and granulation tissue. However, moderate infiltration of acute inflammatory cells was significantly more frequent in group 1 than in group 3. At day 5, the incidence of moderate foreign body residue was significantly higher in group 1 than in group 3. No difference was observed between group 2 and group 4 at day 21 (P > 0.05).

CONCLUSION

OCA is a practical, rapid, and effective method for repairing tongue lacerations. Although infiltration by inflammatory cells and foreign bodies increased in the early period, the long-term results of OCA were indistinguishable from those of suturing.

Current role of cyanoacrylate glue transcatheter embolization in the treatment of acute nonvariceal gastrointestinal bleeding

INTRODUCTION

Over the past three decades, transcatheter arterial embolization (TAE) has become the first-line therapy for the management of acute nonvariceal gastrointestinal bleeding (NVGIB) that is refractory to endoscopic hemostasis. Advances in catheter-based techniques and newer liquid embolic agents, as well as recognition of the effectiveness of minimally invasive treatment options, have expanded the role of interventional radiology in the treatment of acute NVGIB. Many embolic agents have been used successfully. However, no guidelines exist about the choice of the best embolic agent which is still controversial. Cyanoacrylate glue has gained acceptance over time. This article aims to address the current role of TAE using cyanoacrylate glue for the treatment of acute NVGIB.

AREAS COVERED

The authors undertook a literature review of the current evidence on the use of cyanoacrylate glue in treating patients with acute NVGIB.

EXPERT OPINION

The evidence shows that cyanoacrylate glue is the most clinically useful embolic agent in treating patients with acute NVGIB, despite the need for learning curve, especially in case of coagulopathy. At present, research is ongoing to assess liquid embolic agents in the treatment of patients presenting with acute NVGIB. More research is needed but cyanoacrylate glue show promise for the future.

Elastic Biomaterial Scaffold with Spatially Varying Adhesive Design

In order to secure biomaterials to tissue surfaces, sutures or glues are commonly used. Of interest is the development of a biomaterial patch for applications in tissue engineering and regeneration that incorporates an adhesive component to simplify patch application and ensure sufficient adhesion. A separate region dedicated to fulfilling the specific requirements of an application such as mechanical support or tissue delivery is also desirable. Here, the design and fabrication of a unique patch are presented with distinct regions for adhesion and function, resulting in a biomaterial patch resembling the Band-Aid. The adhesive region contains a novel polymer, synthesized to incorporate a molecule capable of adhesion to tissue, dopamine. The desired polymer composition for patch development is selected based on chemical assessment and evaluation of key physical properties such as swelling and elastic modulus, which are tailored for use in soft tissue applications. The selected polymer formulation, referred to as the adhesive patch (AP) polymer, demonstrates negligible cytotoxicity and improves adhesive capability to rat cardiac tissue compared to currently used patch materials. Finally, the AP polymer is used in the patch, designed to possess distinct adhesive and nonadhesive domains, presenting a novel design for the next generation of biomaterials.

Injectable Click Chemistry-based Bioadhesives for Accelerated Wound Closure

Tissue adhesives play a vital role in surgical processes as a substitute for sutures in wound closure. However, several existing tissue adhesives suffer from cell toxicity, weak tissue-adhesive strength, and high cost. In this study, by taking advantage of the fast and specific inverse-demand Diels-Alder cycloaddition reaction, a series of bioadhesives were produced by employing copper-free click chemistry pair trans-cyclooctene (TCO) /tetrazine (Tz) in chitosan. The gelation time of the bioadhesives can be optimized to be less than 2 minutes, which meets the need for surgical wound closure in practice. By adding 4-arm polyethylene glycol propionaldehyde (PEG-PALD) as a co-crosslinker, the adhesive strength of the bioadhesives was optimized to be 2.3 times higher than that of the conventional fibrin glue. Moreover, by adjusting the amount of the co-crosslinker, the swelling ratio and pore size of the chitosan bioadhesives can be tuned to fit the need of drug encapsulation and cell seeding. The chitosan bioadhesives possess no significant in vitro cytotoxicity. Using a mice skin incision wound model, we found that the chitosan bioadhesives were able to close the wound faster and promote wound healing process than the fibrin glue. In conclusion, our results support that the innovative click-chemistry based bioadhesives have been developed with improved physical and biological properties for surgical wound closures. STATEMENT OF SIGNIFICANCE: The manuscript describes a new group of click chemistry-based chitosan bioadhesives fabricated by reacting copper-free click chemistry pair trans-cyclooctene/tetrazine with co-crosslinker PEG-PALD. The new bioadhesives possess the properties of simple preparation, injectability, fast gelation, a minimal cytotoxicity, strong adhesive strength to tissue, and enhanced wound healing responses. This innovative strategy may draw interests of readers from the field of biomaterials, drug delivery, surgical device, and translational medicine.

Laparoscopic Injection of Tissue Adhesives for Inguinal Hernia Repair in a Rabbit Model: Results of an Experimental Comparative Study with the Standard Laparoscopic Inguinal Hernia Repair

Background: The injection of tissue adhesives has been proposed as an alternative to standard laparoscopic inguinal hernia repair but no evidence is available in the pediatric population. This study aimed to evaluate safety, efficacy, and feasibility of injection of tissue adhesives for inguinal hernia repair in a rabbit model. Materials and Methods: Thirty-six New Zealand White male rabbits underwent laparoscopic inguinal hernia repair. In each animal, the hernia defect was repaired using glue on the right side and purse-string suture on the left side. The animals were divided in 3 groups, each 1 of 12 animals, according to the glue used: Glubran 2^® (cyanoacrylate), Histoacryl^® (cyanoacrylate), and BioGlue^® (bovine serum albumin-based). For each group, 6 animals were sacrificed at 7 days postoperatively, and 6 animals at 90 days postoperatively. Histopathological exam of testis and spermatic bundle was performed. Results: The hernia defect was successfully closed on both sides in all cases. The injection of glue was faster than suture repair (P = .001). Postoperative complications (epiploon-parietal adhesions, spermatic vessel ectasia, and hydrocele) rate was significantly higher on the right side compared to the left side at both short- and long-term follow-up (P = .001). Furthermore, a lower maturity of testicles treated by adhesive compared with suture was histologically demonstrated at both short- and long-term follow-up (P = .001). Conclusions: The present experimental study confirmed the feasibility and efficacy of inguinal hernia repair by injection of tissue adhesive. However, several critical issues emerged about the safety of this technique. The use of glue was associated with higher incidence of postoperative complications and significant decrease of testicular maturity compared with standard suture repair. Based upon these preliminary results, repair using suture remains the standard of care for inguinal hernia in children. Further experimental studies are needed to assess the safety of injection of tissue adhesives for pediatric inguinal hernia repair.

In vitro and in vivo evaluation of the safety and efficacy of a novel liquid fiducial marker for image-guided radiotherapy

The true extent of a tumor is difficult to visualize, during radiotherapy, using current modalities. In the present study, the safety and feasibility of a mixture of N-butyl cyanoacrylate and lipiodol (NBCA/Lip) was evaluated in order to investigate the optimal combination for application as a fiducial marker for radiotherapy. Four combinations of NBCA/Lip injection (1:1–0.1, 1:1–0.15, 1:3–0.1 and 1:3–0.15 ml) were injected into the subcutaneous tissue of BALB/c mice. The changes in gross histopathology, body weight, skin score, marker volume, neutrophil and macrophage counts were observed to analyze the effects of the different mixing ratios and injection volumes, in order to identify the best combination. Evaluation according to the International Organization for Standardization criteria was further conducted in order to test the biocompatibility of the mixture, including an acute systematic assay with mice, cytotoxicity with L929 fibroblasts and delayed-type hypersensitivity tests with guinea pigs and an intradermal test with rabbits. The results revealed that at the seventh week, 42 markers (42/48; 87.5%) were still visible using computed tomography (CT) imaging. No serious adverse effects were observed throughout the study period; however, the combination of 1:1–0.1 ml had the lowest body weight and worst skin score. A review of the histopathological reaction to NBCA/Lip revealed a combination of acute inflammation, chronic inflammation, granulation tissue, foreign-body reaction and fibrous capsule formation. The 1:1 NBCA combination ratio resulted in the most intense tissue repair reaction and a slower degradation rate of markers. In general, the combination of 1:3–0.15 ml had a better fusion with local tissue, maintained a stable imaging nodule on CT images for 7 weeks and the final biocompatibility test demonstrated its safety. Overall, the findings of the present study demonstrated NBCA/Lip as a safe and feasible fiducial marker, when using the 1:3–0.15 ml combination.

Embolized cerebral arteriovenous malformations: a multivariate analysis of 101 excised specimens

OBJECTIVE

Endovascular approaches have evolved from a technique practiced at very few centers to a widely available option in the management of arteriovenous malformations (AVMs) of the central nervous system. Embolization can be employed as definitive therapy or as an adjunct to surgical excision. A wide variety of embolic agents have been successfully developed and used in the clinical setting. In addition to facilitating vascular occlusion, embolic agents induce a number of reactive and destructive changes in vessel walls and the surrounding tissue. However, studies examining the pathological changes induced by different embolic agents and varying times of exposure are scarce. The goal of the present study was to compare embolic agents and time of exposure on the pathology in excised specimens.

METHODS

The records of the Department of Pathology at the London Health Sciences Centre were searched for embolized AVMs for the 35-year period 1980-2015. All cases were reevaluated for clinical and technical variables and standardized histopathological findings. Cases were grouped by embolic agent, volume of agent used, and time to excision.

RESULTS

A total of 101 specimens were identified. Embolic agents were invariably associated with a range of pathological findings, some of which may affect the integrity of vessel walls or the reestablishment of flow, thrombosis, acute and chronic inflammatory changes, angionecrosis, extravasation, and recanalization. The type of embolic agent did not predict differences in the incidence or severity of histopathological changes. Larger volumes of embolic agent were associated with a greater proportion of vessels containing embolic material. AVMs excised early (< 1 week postembolization) contained more acute vasculitis, while those excised later (≥ 1 week postembolization) were more likely to exhibit recanalization and foreign body giant cell infiltrates.

CONCLUSIONS

Embolic agents induce a predictable range and temporal progression of pathological changes in cerebral AVMs. The embolic agents studied are indistinguishable in terms of the range and frequency of pathological reactions induced. Greater volumes of embolic agent are associated with more abundant agent within the lesion, but the proportion of vessels and vascular cross-sectional areas containing agent is small. Several changes are significantly associated with time postembolization. Acute vasculitis is a more common finding in the 1st week, while recanalization and foreign body-type granulomatous inflammation are more common at 1 week and beyond.

Advancements in the development on new liquid embolic agents for use in therapeutic embolisation

This review covers the current state-of-the-art in the development of liquid embolics for therapeutic embolisation.

Mussel-Inspired Injectable Hydrogel Adhesive Formed under Mild Conditions Features Near-Native Tissue Properties

Injectable hydrogel adhesives, especially those that can strongly adhere to tissues and feature near-native tissue mechanical properties, are desirable biomaterials for tissue repair. Compared to nonadhesive injectable hydrogels for minimally invasive delivery of therapeutic agents, they can better retain the delivered agents at targeted tissue locations and provide additional local physical barriers. However, regardless of recent advances, an ideal injectable hydrogel adhesive with both proper adhesion and mechanical matching between hydrogels and tissues is yet to be demonstrated with cytocompatible and efficient in situ curing methods. Inspired by marine mussels, where different mussel foot proteins (Mfps) function cooperatively to achieve excellent wet adhesion, we herein report a dual-mode-mimicking strategy by modifying gelatin (Gel) biopolymers with a single-type thiourea-catechol (TU-Cat) functionality to mimic two types of Mfps and their mode of action. This strategy features a minor, yet impactful modification of biopolymers, which gives access to collective properties of an ideal injectable hydrogel adhesive. Specifically, with TU-Cat functionalization of only ∼0.4-1.2 mol % of total amino acid residues, the Mfp-mimetic gelatin biopolymer (Gel-TU-Cat) can be injected and cured rapidly under mild and cytocompatible conditions, giving rise to tissue adhesive hydrogels with excellent matrix ductility, proper wet adhesion, and native tissue-like stress relaxation behaviors. Such a set of properties originating from our novel dual-mode-mimicking strategy makes the injectable hydrogel adhesive a promising platform for cell delivery and tissue repair.

Biomaterials in Gastroenterology: A Critical Overview

In spite of the large diversity of diagnostic and interventional devices associated with gastrointestinal endoscopic procedures, there is little information on the impact of the biomaterials (metals, polymers) contained in these devices upon body tissues and, indirectly, upon the treatment outcomes. Other biomaterials for gastroenterology, such as adhesives and certain hemostatic agents, have been investigated to a greater extent, but the information is fragmentary. Much of this situation is due to the paucity of details disclosed by the manufacturers of the devices. Moreover, for most of the applications in the gastrointestinal (GI) tract, there are no studies available on the biocompatibility of the device materials when in intimate contact with mucosae and other components of the GI tract. We have summarized the current situation with a focus on aspects of biomaterials and biocompatibility related to the device materials and other agents, with an emphasis on the GI endoscopic procedures. Procedures and devices used for the control of bleeding, for polypectomy, in bariatrics, and for stenting are discussed, particularly dwelling upon the biomaterial-related features of each application. There are indications that research is progressing steadily in this field, and the establishment of the subdiscipline of "gastroenterologic biomaterials" is not merely a remote projection. Upon the completion of this article, the gastroenterologist should be able to understand the nature of biomaterials and to achieve a suitable and beneficial perception of their significance in gastroenterology. Likewise, the biomaterialist should become aware of the specific tasks that the biomaterials must fulfil when placed within the GI tract, and regard such applications as both a challenge and an incentive for progressing the research in this field.

Cyanacrylate Glue Caused Extrinsic Compression of an Infrapopliteal Vein Graft

Several surgical sealant devices are commercially available after their rigorous clinical testing with no apparent complications reported so far in the current literature. Cyanoacrylate glue can be used to stabilize the anastomoses and permit a better tensile strength in cardiovascular surgery. We first report the case of a 71-year-old male patient presenting with symptoms of progressive limitation of walking distance, 13 months after a successful femoroinfrapopliteal bypass surgery, because of a calcified tissue extrinsically stenosizing the first segment of the previous bypass graft, caused by the use of cyanoacrylate glue.

Molecular Staples for Tough and Stretchable Adhesion in Integrated Soft Materials

The integration of soft materials-biological tissues, gels, and elastomers-is a rapidly developing technology of this time. Whereas hard materials are adhered using adhesives of hard polymers since antiquity, these hard polymers are generally unsuited to adhere soft materials, because hard polymers constrain the deformation of soft materials. This paper describes a design principle to use hard polymers to adhere soft materials, such that adhesion remains tough after the adhered soft materials are subject to many cycles of large stretches in the plane of their interface. The two soft materials have stretchable polymer networks, but need not have functional groups for adhesion. The two soft materials are adhered by forming, in situ at their interface, islands of a hard polymer. The adhesion is tough if the islands themselves are strong, and the polymers of the islands are in topological entanglement with the polymer networks of the soft materials. The adhesion is stretchable if the islands are smaller than the flaw sensitivity length. Several methods of forming the hard polymer islands are demonstrated, and the mechanics and chemistry of adhesion are studied. The design principle will enable many hard polymers to form tough and stretchable adhesion between soft materials.

Bioinspired Adhesive Architectures: From Skin Patch to Integrated Bioelectronics

The attachment phenomena of various hierarchical architectures found in nature have extensively drawn attention for developing highly biocompatible adhesive on skin or wet inner organs without any chemical glue. Structural adhesive systems have become important to address the issues of human-machine interactions by smart outer/inner organ-attachable devices for diagnosis and therapy. Here, advances in designs of biologically inspired adhesive architectures are reviewed in terms of distinct structural properties, attachment mechanisms to biosurfaces by physical interactions, and noteworthy fabrication methods. Recent demonstrations of bioinspired adhesive architectures as adhesive layers for medical applications from skin patches to multifunctional bioelectronics are presented. To conclude, current challenges and prospects on potential applications are also briefly discussed.

Composite Double-Network Hydrogels To Improve Adhesion on Biological Surfaces

Despite the development of hydrogels with high mechanical properties, insufficient adhesion between these materials and biological surfaces significantly limits their use in the biomedical field. By controlling toughening processes, we designed a composite double-network hydrogel with ∼90% water content, which creates a dissipative interface and robustly adheres to soft tissues such as cartilage and meniscus. A double-network matrix composed of covalently cross-linked poly(ethylene glycol) dimethacrylate and ionically cross-linked alginate was reinforced with nanofibrillated cellulose. No tissue surface modification was needed to obtain high adhesion properties of the developed hydrogel. Instead, mechanistic principles were used to control interfacial crack propagation. Comparing to commercial tissue adhesives, the integration of the dissipative polymeric network on the soft tissue surfaces allowed a significant increase in the adhesion strength, such as ∼130 kPa for articular cartilage. Our findings highlight the significant role of controlling hydrogel structure and dissipation processes for toughening the interface. This research provides a promising path to the development of highly adhesive hydrogels for tissues repair.

Properties of temporary adhesion systems of marine and freshwater organisms

Underwater adhesive secretions are a promising source of inspiration for biomedical and industrial applications. Although marine permanent adhesives have been extensively investigated, reversible adhesion, e.g. as used for locomotion and feeding, is still poorly understood. Here, we summarise the current knowledge on secretion-based, temporary adhesive systems in aquatic environments, with a special emphasis on the morphology and structure of adhesive organs and adhesive material. Many animals employing temporary adhesion to the substratum rely on so-called duo-gland adhesive organs, consisting of two secretory gland cells and one supportive cell. We give a detailed depiction of a basic duo-gland adhesive organ and variations thereof. Additionally, we discuss temporary adhesive systems with an alternative building plan. Next, the topography of secreted adhesive footprints is described based on examples. The limited data on the composition of temporary adhesives are summarised, separating known protein components and carbohydrate residues. There are still large gaps in our understanding of temporary adhesion. We discuss three proposed models for detachment, although the actual mechanism of voluntary detachment is still a matter for debate.

Portal Vein Embolization: Correlation of Future Liver Remnant Hypertrophy to Type of Embolic Agent Used

Purpose

The purpose of this study was to compare the effectiveness of portal vein embolization (PVE) with different embolic agents used at our centre. Specifically, the effectiveness of N-butyl cyanoacrylate (NBCA) glue is compared with that of polyvinyl alcohol (PVA) particles.

Methods

We performed a retrospective chart review of all patients (N = 77) who underwent PVE at our institution over a 5-year period. Pre- and postprocedural computed tomography or magnetic resonance imaging, when available, were used to measure the volume of total liver volume and future liver remnant (FLR). The absolute values obtained were used to calculate percentage of FLR. The growth in FLR was determined 4–6 weeks after PVE. Technical details of the procedure including the type and amount of embolic agent used were obtained from the chart reviews, electronic patient records, and radiology reports. Statistical analysis was performed using Kruskal-Wallis test, Wilcoxon rank sum test, and the Spearman correlation coefficient with post hoc analysis. Results are expressed as mean ± SD ( P < .05 considered statistically significant).

Results

NBCA (n = 29) produced a mean change in FLR of 14.8% compared with 9.3% for PVA particles (n = 24; P = .007). Mean change in FLR was 10.1% in the group where a combination of NBCA and PVA particles was used (n = 24). The effect of glue volume and glue-to-lipiodol ratio on the outcome was not found to be statistically significant ( P = .5 and .7, respectively).

Conclusions

We conclude that NBCA glue is a better embolic agent than PVA particles in inducing liver hypertrophy.

Arteriovenous Malformations: Syndrome Identification and Vascular Management

PURPOSE OF REVIEW

Vascular malformations represent a poorly understood set of conditions that create considerable diagnostic and therapeutic confusion. Historically, extensive surgical resections yielded poor results. More recently, the treatment paradigm has shifted to endovascular therapy such that embolization and sclerotherapy are now considered the first line of treatment. Although there is still a role for traditional surgical techniques, it is now most commonly integrated with endovascular therapies in a hybrid fashion. The goal of this review is to provide a greater understanding of the diagnosis and treatment of vascular malformations.

RECENT FINDINGS

Vascular malformations can be high-flow (arteriovenous shunting) or low-flow (venous or lymphatic). Clinical presentation and treatment is different for each. Treatment of high-flow lesions must be directed at reducing or eliminating the nidus, usually via super-selective catheterization and embolization. Low-flow lesions are usually treated by direct injection of sclerosing agents under fluoroscopic or ultrasound guidance. The cornerstone of managing patients with vascular malformations is making the proper diagnosis, which is often challenging. Even after a diagnosis is made, therapy itself may be challenging and generate frustration among patients and providers. Frequently, the treatment of vascular malformations is characterized by only slow and incremental improvements without complete lesion eradication. By combining a thorough understanding of the vascular malformation disease process with an array of endovascular techniques, vascular interventionalists may contribute greatly to the care of these patients.

Cerebral arteriovenous malformations in the era of embolization for angiographic cure: a single-center experience in Egypt

Background

Embolization for cerebral arteriovenous malformations (AVMs) has evolved in the last decade with evolution in both equipment and material. Embolization targets have expanded to include angiographic cure.

Methods

To discuss the technical and management outcomes of our first cerebral AVM case series treated with embolization. The clinical, angiographic, treatment, and outcome variables of consecutive cerebral arteriovenous malformation cases, treated with curative embolization, between January 2011 and June 2017 in one regional center, were retrospectively analyzed.

Results

In 21 patients, 21 AVMs were identified, and 13 patients (61.9%) were males. The mean of the age was 34.24 ± 12.99. Fifteen patients (71.4%) had a history of intracranial hemorrhage, and 10 (47.6%) patients had seizures. Sixteen patients (76.2%) were at grade 1 of modified Rankin Scale (mRS) at admission. The median for modal Spetzler-Martin grade was 2. The average number of arterial feeders was 3. Direct arteriovenous fistulas were found in 4 cases (19.0%). Venous aneurysms were found in 4 cases (19.0%). Seventeen AVMs (80.9%) were considered high bleeding risk lesions. Forty-three embolization sessions were done. Early hemorrhage occurred in 3 sessions (7.0%). Vessel perforation occurred 1 session (2.3%). Poor outcome occurred in 1 patient that was discharged at grade 3 mRS. Angiographic cure was achieved in 9 patients (42.9%). The average size reduction was 65%.

Conclusions

Onyx embolization could serve as a curative option for AVM treatment with accepted morbidity and mortality.

Portal Vein Embolization Utilizing N-Butyl Cyanoacrylate for Contralateral Lobe Hypertrophy Prior to Liver Resection: A Systematic Review and Meta-Analysis

PURPOSE

To evaluate the safety and effectiveness of n-butyl cyanoacrylate (NBCA) for portal vein embolization (PVE) when used to induce contralateral future liver remnant (FLR) hypertrophy in patients undergoing planned hepatic resection for hepatic malignancy.

MATERIALS AND METHODS

The PubMed database (including articles indexed by MEDLINE) was searched for articles published from 1970 to 2018 describing patients treated with PVE utilizing NBCA to induce hypertrophy of the FLR prior to contralateral hepatic lobe resection. Demographic data, embolization technique, complications of embolization, resultant FLR hypertrophy, and surgical outcomes were obtained when available. A meta-analysis was performed to determine the cumulative relative hypertrophy rate of the FLR following PVE with NBCA.

RESULTS

The literature search yielded 18 relevant articles. Six hundred and seven patients (383 men, 220 women; mean age 60.7 years) with procedures describing PVE utilizing NBCA were reviewed. The most common underlying hepatic malignancies were colorectal metastases (n = 348), followed by cholangiocarcinomas (n = 92), and hepatocellular carcinomas (n = 89). Technical success was reportedly achieved in 603/607 patients, for a success rate of 99.3%. Fixed effects meta-analysis of the relative hypertrophy rate of the FLR among studies resulted in an aggregate rate of 49.4 ± 1.3%. Of the patients who underwent attempted PVE, 461/607 (75.9%) eventually underwent surgical resection. Major complications following PVE occurred in 19 patients (3.13%), while minor complications following PVE occurred in 38 patients (6.26%).

CONCLUSIONS

PVE utilizing NBCA to induce hypertrophy of the FLR prior to contralateral lobe resection in the setting of hepatic malignancy is safe and effective.

LEVEL OF EVIDENCE

Level IIa-Systematic review of cohort studies.

Non-thermal endovenous treatment: acrylate adhesion of varicose saphenous veins

Endovenous treatment of varicose veins, especially thermal procedures using laser and radio frequencies, has become established as an effective alternative to surgery by stripping and high ligation. Although these methods are very sparing and patient-friendly, they also entail risks and side effects. The risk of damage to peripheral and motor nerves is certainly lower than with open surgery, however it still exists as a result of heat application and tumescent anaesthesia.

Several non-thermal procedures which do not require the use of tumescent anaesthesia are coming onto the market. They carry a significantly lower risk of nerve lesions while remaining highly effective. The present work analyses the current state of knowledge on the latest to be developed, cyanoacrylate adhesion of incompetent saphenous veins.

VenaSeal™ closure treatment of saphenous varicosis

Einführung: Zur Behandlung der Stammvarikose mit dem VenaSeal™ Closure-System ist eine Narkoseform oder Tumeszenzanästhesie nicht erforderlich. Ebenfalls kann auf das Tragen von Kompressionsstrümpfen verzichtet werden. Über die Anwendung, erste Erfahrungen und 2 Jahresergebnisse wird berichtet.

Material und Methode: In der Zeit von März 2012 bis Mai 2014 wurden 218 Patienten an 274 Stammvenen mit dem VenaSeal™ Closure-System therapiert. Doppler und Duplexuntersuchungen erfolgten nach 7 Tagen, 6 Wochen, 1 Jahr und 2 Jahren. Erhoben wurde die Verschluss- und Komplikationsrate, der visuelle analoge Schmerz-Score und der Venous Clinical Severity Score(VCSS).

Ergebnisse: Nachuntersucht wurden 227 Stammvenen der Vena saphena magna (VSM) und 24 Stammvenen der Vena saphena parva (VSP). Die Verschlussrate der VSM betrug 99,5 % (n= 227) nach 7 Tagen, 96,5 % nach 6 Wochen (n= 172), 93,4 % nach 1 Jahr (n= 61) und 100 % nach 2 Jahren (n= 20). Die Verschlussrate der VSP betrug jeweils 100 % nach 7 Tagen (n= 24), 6 Wochen (n= 12) und nach 1 Jahr (n=4). Majorkomplikationen traten nicht auf. Als Minorkomplikationen traten nach Behandlung der Vena saphena magna inflammatorische Reaktionen bei 44 Beinen und Phlebitiden bei 32 Beinen auf. Der Pain Score entwickelte sich unter der Behandlung von 1,4 auf 1,5 (3. Tag), 2,1 (5. Tag), 1,6 (10. Tag), 0,2 (4 Wochen) auf 0,1 (6 Wochen). Der VCSS betrug präoperativ 4,4 und sank auf 2,9 (7. Tag), 2,1 (6 Wochen) auf 1,8 (1 und 2 Jahr)

Diskussion: Die VenaSeal™ Closure-Behand-lung der Stammvarikose ist sicher und effektiv. Die Ergebnisse sind vergleichbar denen der thermischen Ablationsverfahren. Ohne die Anwendung der Tumeszenz-Anästhesie haben die Patientin deutlich weniger Beschwerden im Vergleich zu den thermischen Ablationsverfahren, sowohl während der Behandlung, als auch postoperativ.

Tough adhesives for diverse wet surfaces

Adhesion to wet and dynamic surfaces, including biological tissues, is important in many fields but has proven to be extremely challenging. Existing adhesives are cytotoxic, adhere weakly to tissues, or cannot be used in wet environments. We report a bioinspired design for adhesives consisting of two layers: an adhesive surface and a dissipative matrix. The former adheres to the substrate by electrostatic interactions, covalent bonds, and physical interpenetration. The latter amplifies energy dissipation through hysteresis. The two layers synergistically lead to higher adhesion energies on wet surfaces as compared with those of existing adhesives. Adhesion occurs within minutes, independent of blood exposure and compatible with in vivo dynamic movements. This family of adhesives may be useful in many areas of application, including tissue adhesives, wound dressings, and tissue repair.

Correcting Concavity of Rabbit Auricular Cartilage: Comparison of Single Scoring Incisions with Butyl Cyanoacrylate-Aided Techniques

BACKGROUND

The authors present the results of an experimental study in which four different techniques were used for the correction of concave rabbit auricular cartilage.

METHODS

Sixteen New Zealand adult male rabbits were used in the study. Butyl cyanoacrylate-aided cartilage graft fixation and butyl cyanoacrylate-aided bone graft fixation and scoring technique, alone or combined with butyl cyanoacrylate application, were performed to correct the concavity of rabbit auricular cartilage.

RESULTS

Angle measurements showed that all four techniques were efficient for correction of the cartilage concavities. However, the mean postsacrifice angles of the graft fixation groups were significantly higher than those of the other study groups, reflecting the fact that graft fixation with butyl cyanoacrylate application was more efficient for preserving the final cartilage shape. Furthermore, in the ninth month, graft fixation groups had the lowest chondrocyte densities, the highest degree of inflammation, the highest degree of foreign body reaction, and the highest butyl cyanoacrylate density.

CONCLUSIONS

Fibrosis or chondrocyte proliferation on scoring incision lines is not an associated feature of this technique. When the incision depths were standardized, the scoring technique provided efficacy similar to that of the scoring incisions combined with butyl cyanoacrylate application for correction of the cartilage concavity. The scoring incision plus butyl cyanoacrylate group showed less toxicity than the graft fixation groups because of rapid removal of toxic breakdown products. Graft fixation techniques were superior to other corrective procedures with regard to preservation of the final cartilage shape. Although they resulted in greater toxicity, the cartilage correction was not affected unfavorably.

Polymeric materials for embolic and chemoembolic applications

Percutaneous transcatheter embolization procedures involve the selective occlusion of blood vessels. Occlusive agents, referred to as embolics, vary in material characteristics including chemical composition, mechanical properties, and the ability to concurrently deliver drugs. Commercially available polymeric embolics range from gelatin foam to synthetic polymers such as poly(vinyl alcohol). Current systems under investigation include tunable, bioresorbable microspheres composed of chitosan or poly(ethylene glycol) derivatives, in situ gelling liquid embolics with improved safety profiles, and radiopaque embolics that are trackable in vivo. This article reviews commercially available materials used for embolization as well as polymeric materials that are under investigation.

Preclinical study on an animal model of a new non-adhesive cyanoacrylate (Purefill®) for arterial embolization

PURPOSE

The goal of this study was to assess the distal dispersion, the adhesion strength to catheter, the vascular toxicity and the ability in excluding embolized vessels using Purefill^® (α-hexil-cyanoacrylate) as embolic material, which is a new high purity cyanoacrylate and compare these results with those obtained with N-butyl-2-cyanoacrylate (Histoacryl^®) and a mixture of N-butyl-2-cyanoacrylate and methacryloxysulfolane.

MATERIAL AND METHODS

In six pigs, the right rete mirabile (RM) and right renal arteries were embolized with α-hexil-cyanoacrylate, and the left rete mirabile and left renal artery were embolized with N-butyl-2-cyanoacrylate and N-butyl-2-cyanoacrylate+Methacryloxysulfolane for comparison. One minute after glue injection through the microcatheter, displacements of the kidney and the pharyngeal artery were measured on angiographic images, before exercising any traction and during catheter pulling, when the forces were maximal. Displacement was measured in terms of distance (mm) with respect to renal pedicles and in terms of angle (°) with respect to the rete. After acute embolization (4 pigs) or three-month follow-up (2 pigs), the kidneys and the RM were removed and further analysed using computed tomography and histopathological examination.

RESULTS

Similar short and long-term embolic efficacies were observed with the three glues. The mean displacement distances of renal pedicles were 2.6mm for α-hexil-cyanoacrylate, 22.6mm for N-butyl-2-cyanoacrylate and 19.8mm for N-butyl-2-cyanoacrylate+Methacryloxysulfolane (P=0.021). The mean angles of displacement of the ascending pharyngeal arteries were for 12.2° for α-hexil-cyanoacrylate, 23.5° for N-butyl-2-cyanoacrylate and 30° for N-butyl-2-cyanoacrylate+Methacryloxysulfolane (P=0.070). Histopathologically, findings were similar for the three glues, immediately and 90 days after embolization.

CONCLUSION

α-hexil-cyanoacrylate has occlusive efficacy in the short and long term similar to those of N-butyl-2-cyanoacrylate and N-butyl-2-cyanoacrylate+Methacryloxysulfolane. In addition, histopathological changes are similar with the three glues immediately or 90 days after embolization. Conversely, α-hexil-cyanoacrylate results in a reduced angle and distance of displacement compared to the other two glues, assumably reflecting a limited adhesive strength.