Cytotoxicity of Cyanoacrylate-Based Tissue Adhesives and Short-Term Preclinical In Vivo Biocompatibility in Abdominal Hernia Repair

A Mechanically Resilient Soft Hydrogel Improves Drug Delivery for Treating Post-Traumatic Osteoarthritis in Physically Active Joints

Intra-articular delivery of disease-modifying osteoarthritis drugs (DMOADs) is likely to be most effective in early post-traumatic osteoarthritis (PTOA) when symptoms are minimal and patients are physically active. DMOAD delivery systems therefore must withstand repeated mechanical loading without affecting the drug release kinetics. Although soft materials are preferred for DMOAD delivery, mechanical loading can compromise their structural integrity and disrupt drug release. Here, we report a mechanically resilient soft hydrogel that rapidly self-heals under conditions resembling human running while maintaining sustained release of the cathepsin-K inhibitor L-006235 used as a proof-of-concept DMOAD. Notably, this hydrogel outperformed a previously reported hydrogel designed for intra-articular drug delivery, used as a control in our study, which neither recovered nor maintained drug release under mechanical loading. Upon injection into mouse knee joints, the hydrogel showed consistent release kinetics of the encapsulated agent in both treadmill-running and non-running mice. In a mouse model of aggressive PTOA exacerbated by treadmill running, L-006235 hydrogel markedly reduced cartilage degeneration. To our knowledge, this is the first hydrogel proven to withstand human running conditions and enable sustained DMOAD delivery in physically active joints, and the first study demonstrating reduced disease progression in a severe PTOA model under rigorous physical activity, highlighting the hydrogel's potential for PTOA treatment in active patients.

Effects of cyanoacrylate on leakage pressures of cooled canine cadaveric jejunal enterotomies

OBJECTIVE

To compare the intraluminal initial and maximal pressures of enterotomies closed using three different techniques (single-layer appositional continuous closure; closure with cyanoacrylate; a single-layer appositional closure augmented with cyanoacrylate) in a cooled canine cadaveric jejunal model and to report the initial leak location in all samples.

STUDY DESIGN

Experimental, ex-vivo study.

SAMPLE POPULATION

Grossly normal chilled small intestine segments from three canine cadavers.

METHODS

A total of 45 chilled jejunal segments (n = 15 segments/group) were assigned to a handsewn group (HSE), a cyanoacrylate only group (CE) and a handsewn and cyanoacrylate group (HS + CE). A 2 cm antimesenteric enterotomy was performed and closure with one of the above techniques. Initial leakage pressures (ILP), maximal intraluminal pressures (MIP) and initial leakage location were recorded by a single observer.

RESULTS

Handsewn enterotomies leaked at higher ILP when augmented with cyanoacrylate (83.3 ± 4.6 mmHg, p < .001) compared to both the HSE group (43.8 ± 5.3 mmHg) and the CE group (18.6 ± 3.5 mmHg). Those sealed with cyanoacrylate only leaked at a lower MIP compared with the other groups (p < .001). Maximal intraluminal pressures did not differ between handsewn enterotomies, whether augmented or not (p = .19).

CONCLUSION

Reinforcement of a sutured enterotomy closure with cyanoacrylate was easy to perform and resulted in significantly increased initial leak pressures in cadaveric jejunum.

CLINICAL SIGNIFICANCE

The increased leakage pressures achieved by reinforcing enterotomies with cyanoacrylate could consequently reduce the incidence of postoperative intestinal leakage following an enterotomy and may result in reduced patient morbidity or mortality.

Development of a Cell Culture Chamber for Investigating the Therapeutic Effects of Electrical Stimulation on Neural Growth

Natural electric fields exist throughout the body during development and following injury, and, as such, EFs have the potential to be utilized to guide cell growth and regeneration. Electrical stimulation (ES) can also affect gene expression and other cellular behaviors, including cell migration and proliferation. To investigate the effects of electric fields on cells in vitro, a sterile chamber that delivers electrical stimuli is required. Here, we describe the construction of an ES chamber through the modification of an existing lid of a 6-well cell culture plate. Using human SH-SY5Y neuroblastoma cells, we tested the biocompatibility of materials, such as Araldite®, Tefgel™ and superglue, that were used to secure and maintain platinum electrodes to the cell culture plate lid, and we validated the electrical properties of the constructed ES chamber by calculating the comparable electrical conductivities of phosphate-buffered saline (PBS) and cell culture media from voltage and current measurements obtained from the ES chamber. Various electrical signals and durations of stimulation were tested on SH-SY5Y cells. Although none of the signals caused significant cell death, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays revealed that shorter stimulation times and lower currents minimized negative effects. This design can be easily replicated and can be used to further investigate the therapeutic effects of electrical stimulation on neural cells.

Adhesivity-tuned bioactive gelatin/gellan hybrid gels drive efficient wound healing

Gelatin-based hydrogels have been widely used for wound healing applications. However, increase in ligand density and reduction in pore size with increasing gelatin concentration may delay wound healing by limiting cell infiltration. In this study, we address this shortcoming by combining gelatin with gellan-which is super hydrophilic and non-adhesive to cells. We show that UV crosslinked hybrid gels composed of methacrylated gelatin (GelMA) and methacrylated gellan gum (mGG), possess considerably larger pores and improved mechanical properties compared to GelMA gels. Reduced spreading and reduced formation of focal adhesions on hybrid gels combined with lower contractility and faster detachment upon trypsin-induced de-adhesion suggests that hybrid gels are less adhesive than GelMA gels. Gradual release of fibroblast growth factor (FGF) and silver nanoparticles (AgNPs) incorporated in hybrid gels not only boosts cell migration, but also confers anti-bacterial activity against gram-positive and gram-negative bacteria at concentrations nontoxic to cells. Full thickness wound healing in Wistar rats revealed increased granulation tissue formation in hybrid gels, fastest epithelialization and highest collagen deposition in rats treated with FGF entrapped hybrid gels. Together, our results demonstrate how adhesive tuning and incorporation of bioactive factors can be synergistically combined for achieving complete wound healing.

Bioadhesive Technology Platforms

Bioadhesives have emerged as transformative and versatile tools in healthcare, offering the ability to attach tissues with ease and minimal damage. These materials present numerous opportunities for tissue repair and biomedical device integration, creating a broad landscape of applications that have captivated clinical and scientific interest alike. However, fully unlocking their potential requires multifaceted design strategies involving optimal adhesion, suitable biological interactions, and efficient signal communication. In this Review, we delve into these pivotal aspects of bioadhesive design, highlight the latest advances in their biomedical applications, and identify potential opportunities that lie ahead for bioadhesives as multifunctional technology platforms.

Bioadhesives with Antimicrobial Properties

Bioadhesives with antimicrobial properties enable easier and safer treatment of wounds as compared to the traditional methods such as suturing and stapling. Composed of natural or synthetic polymers, these bioadhesives seal wounds and facilitate healing while preventing infections through the activity of locally released antimicrobial drugs, nanocomponents, or inherently antimicrobial polers. Although many different materials and strategies are employed to develop antimicrobial bioadhesives, the design of these biomaterials necessitates a prudent approach as achieving all the required properties including optimal adhesive and cohesive properties, biocompatibility, and antimicrobial activity can be challenging. Designing antimicrobial bioadhesives with tunable physical, chemical, and biological properties will shed light on the path for future advancement of bioadhesives with antimicrobial properties. In this review, the requirements and commonly used strategies for developing bioadhesives with antimicrobial properties are discussed. In particular, different methods for their synthesis and their experimental and clinical applications on a variety of organs are reviewed. Advances in the design of bioadhesives with antimicrobial properties will pave the way for a better management of wounds to increase positive clinical outcomes.

Genetically Engineered Protein-Based Bioadhesives with Programmable Material Properties

Silk-amyloid-mussel foot protein (SAM) hydrogels made from recombinant fusion proteins containing β-amyloid peptide, spider silk domain, and mussel foot protein (Mfp) are attractive bioadhesives as they display a unique combination of tunability, biocompatibility, bioabsorbability, strong cohesion, and underwater adhesion to a wide range of biological surfaces. To design tunable SAM hydrogels for tailored surgical repair applications, an understanding of the relationships between protein sequence and hydrogel properties is imperative. Here, we fabricated SAM hydrogels using fusion proteins of varying lengths of silk-amyloid repeats and Mfps to characterize their structure and properties. We found that increasing silk-amyloid repeats enhanced the hydrogel's β-sheet content (r = 0.74), leading to higher cohesive strength and toughness. Additionally, increasing the Mfp length beyond the half-length of the full Mfp sequence (1/2 Mfp) decreased the β-sheet content (r = -0.47), but increased hydrogel surface adhesion. Among different variants, the hydrogel made of 16xKLV-2Mfp displayed a high ultimate strength of 3.0 ± 0.3 MPa, an ultimate strain of 664 ± 119%, and an attractive underwater adhesivity of 416 ± 20 kPa to porcine skin. Collectively, the sequence-structure-property relationships learned from this study will be useful to guide the design of future protein adhesives with tunable characteristics for tailored surgical applications.

Polymer nanomaterials for use as adjuvant surgical tools

Materials employed in the treatment of conditions encountered in surgical and clinical practice frequently face barriers in translation to application. Shortcomings can be generalized through their reduced mechanical stability, difficulty in handling, and inability to conform or adhere to complex tissue surfaces. To overcome an amalgam of challenges, research has sought the utilization of polymer-derived nanomaterials deposited in various fashions and formulations to improve the application and outcomes of surgical and clinical interventions. Clinically prevalent applications include topical wound dressings, tissue adhesives, surgical sealants, hemostats, and adhesion barriers, all of which have displayed the potential to act as superior alternatives to current materials used in surgical procedures. In this review, emphasis will be placed not only on applications, but also on various design strategies employed in fabrication. This review is designed to provide a broad and thought-provoking understanding of nanomaterials as adjuvant tools for the assisted treatment of pathologies prevalent in surgery. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

Tentacle Mesh for Fixation-Free Spigelian Hernia Repair: Mini-Invasive Approach Granting Broad Defect Overlap

BACKGROUND

Compared to other types of abdominal protrusions, Spigelian hernias are not very common. In prosthetic repair of abdominal protrusions, mesh fixation and defect overlap are an open issue, as they are a source of complications. A newly developed tentacle-shaped mesh has been used to ensure a fixation-free repair with a broader defect overlap in the repair of abdominal hernias. This study describes the long-term results of a fixation-free repair of Spigelian hernias carried out with a tentacle mesh.

METHODS

A proprietary mesh composed of a central body with integrated radiating arms was used for repairing Spigelian hernias in 54 patients. The implant was positioned in preperitoneal sublay, and the straps were delivered across the abdominal musculature with a needle passer, and then, after fascia closure, cut short in the subcutaneous layer.

RESULTS

The friction of the straps passing through the abdominal wall served to hold the mesh in place, guaranteeing a wide overlap over the defect without fixation. In a long-term follow-up of 6 to 84 months (mean 64 months), a very low rate of complications occurred, but no recurrence was reported.

CONCLUSIONS

The tentacle strap system of the prosthesis allowed for an easy, fast and safe fixation-free placement granting a wide overlap, avoiding intraoperative complications. Greatly reduced pain and a negligible amount of postoperative complications characterized the postoperative outcome.

Electrospun Scaffolds Based on Poly(butyl cyanoacrylate) for Tendon Tissue Engineering

Tendon disorders are common medical conditions that could lead to significant disability, pain, healthcare costs, and a loss of productivity. Traditional approaches require long periods of treatment, and they largely fail due to the tissues weakening and the postoperative alterations of the normal joint mechanics. To overcome these limitations, innovative strategies for the treatment of these injuries need to be explored. The aim of the present work was the design of nano-fibrous scaffolds based on poly(butyl cyanoacrylate) (PBCA), a well-known biodegradable and biocompatible synthetic polymer, doped with copper oxide nanoparticles and caseinphosphopeptides (CPP), able to mimic the hierarchical structure of the tendon and to improve the tissue healing potential. These were developed as implants to be sutured to reconstruct the tendons and the ligaments during surgery. PBCA was synthetized, and then electrospun to produce aligned nanofibers. The obtained scaffolds were characterized for their structure and physico-chemical and mechanical properties, highlighting that CuO and CPP loading, and the aligned conformation determined an increase in the scaffold mechanical performance. Furthermore, the scaffolds loaded with CuO showed antioxidant and anti-inflammatory properties. Moreover, human tenocytes adhesion and proliferation to the scaffolds were assessed in vitro. Finally, the antibacterial activity of the scaffolds was evaluated using Escherichia coli and Staphylococcus aureus as representative of Gram-negative and Gram-positive bacteria, respectively, demonstrating that the CuO-doped scaffolds possessed a significant antimicrobial effect against E. coli. In conclusion, scaffolds based on PBCA and doped with CuO and CPP deserve particular attention as enhancers of the tendon tissue regeneration and able to avoid bacterial adhesion. Further investigation on the scaffold efficacy in vivo will assess their capability for enhancing the tendon ECM restoration in view of accelerating their translation to the clinic.

Multifunctional Dual Cross-Linked Bioadhesive Patch with Low Immunogenic Response and Wet Tissues Adhesion

The development of bioadhesives is an important, yet challenging task as seemingly mutually exclusive properties need to be combined in one material, that is, strong adhesion, water resistance, and high biocompatibility. Here, a biocompatible and biodegradable protein-based bioadhesive patch (PBP) with high adhesion strength and low immunogenic response is reported. PBP exists as a strong adhesion for biological surfaces, which is higher than some conventional bioadhesives (i.e., polyethylene glycol and fibrin). Robust adhesion and strength are realized through the removal of interfacial water and fast formation of multiple supramolecular interactions induced by metal ions. The PBP's high biocompatibility is evaluated and immunogenic response in vitro and in vivo is neglected. The strong adhesion on soft biological tissues qualifies the PBP as biomedical glue outperforming some commercial products for applications in hemostasis performance, accelerated wound healing, and sealing of defected organs, anticipating to be useful as a tissue adhesive and sealant.

A Dual-network Nerve Adhesive with Enhanced Adhesion Strength Promotes Transected Peripheral Nerve Repair

Peripheral nerve transection has a high prevalence and results in functional loss of affected limbs. The current clinical treatment using suture anastomosis significantly limits nerve recovery due to severe inflammation, secondary damage, and fibrosis. Fibrin glue, a commercial nerve adhesive as an alternative, avoids secondary damage but suffers from poor adhesion strength. To address their limitations, a highly efficacious nerve adhesive based on dual-crosslinking of dopamine-isothiocyanate modified hyaluronic acid and decellularized nerve matrix is reported in this paper. This dual-network nerve adhesive (DNNA) shows controllable gelation behaviors feasible for surgical applications, robust adhesion strength, and promoted axonal outgrowth in vitro. The in vivo therapeutic efficacy is tested using a rat-based sciatic nerve transection model. The DNNA decreases fibrosis and accelerates axon/myelin debris clearance at 10 days post-surgery, compared to suture and commercial fibrin glue treatments. At 10 weeks post-surgery, the strong adhesion and bioactivity allow DNNA to significantly decrease intraneural inflammation and fibrosis, enhance axon connection and remyelination, aid motor and sensory function recovery, as well as improve muscle contraction, compared to suture and fibrin treatments. Overall, this dual-network hydrogel with robust adhesion provides a rapid and highly efficacious nerve transection treatment to facilitate nerve repair and neuromuscular function recovery.

Fixation free laparoscopic obliteration of inguinal hernia defects with the 3D dynamic responsive scaffold ProFlor

Laparoscopic TAPP/TEP approaches are well-established options for the cure of inguinal hernias. As in the open approach, mesh fixation and poor-quality biologic response represent controversial questions and are a source of concerns. Furthermore, hernia defect patency represents another problem which seems not well acknowledged among surgeons. These problems are considered the cause of frequent intra and postoperative complications. To overcome these concerns, recently a different concept of cure has emerged. Based on a newly developed dynamic responsive 3D scaffold named ProFlor, a permanent hernia defect obliteration has been finalized. Following its inherent centrifugal expansion due to its dynamic responsivity, this hernia device is positioned fixation free within the defect and induces a probiotic biological response allowing for the re-establishment of the degenerated inguinal barrier. A laparoscopic approach with the 3D scaffold has been tested on 71 patients to demonstrate its effectiveness in reducing intra and postoperative complications. The operated patients presented with bilateral and/or recurrent inguinal hernia. Overall, 122 hernia defects were obliterated with 119 dynamic responsive scaffolds. The procedures were carried out from January 2018 to January 2022 with a defined protocol and detailed procedural steps. The laparoscopic technique with the 3D hernia scaffold allowed for fixation free placement, permanent defect obliteration and dynamically induced regenerative effects. The technique proved effective in reducing intra and postoperative complications. In particular, early postoperative pain and discomfort significantly decreased. No chronic pain and no recurrences were reported during follow up. The results achieved with the described laparoscopic technique seem to embody an innovative concept for inguinal hernia repair. Fixation free, dynamic responsive, permanent defect obliteration, histologically proven regenerative effects are the distinctive features of this 3D scaffold. It seems to embody a more physiological and pathogenetically coherent concept of cure, thus improving treatment results of this widespread disease.

Biocompatibility of novel albumin-aldehyde surgical adhesive

Many medical procedures could benefit from the use of tissue sealants which allow for reduced surgery time, limited blood loss, easier tissue handling, and fewer postoperative complications. The safety and biocompatibility of surgical sealants are of paramount importance therefore, the aim of this study is to investigate the biocompatibility of NE’X Glue Surgical Adhesive. Chemical characterization (VOC and elements), cytotoxicity (MEM elution), genotoxicity (AMES and MLA), endotoxin contamination, sensitization potential, intracutaneous reactivity, acute and subchronic systemic toxicity with implantation as well as pyrogenicity were evaluated to investigate the biocompatibility of the NE’X Glue Surgical Adhesive. Studies were conducted according to ISO 10993 standards. The biocompatibility requirements with accordance to ISO 10993-1 for NE'X Glue were met. In vitro studies showed that NE'X Glue surgical adhesive is non-cytotoxic and non-mutagenic. Also, in vivo studies demonstrated that NE'X Glue shows no signs of toxicity, has no pyrogenic potential, and is non-sensitizing and non-irritating. The chemical characterization showed that no compounds were identified above Analytical Evaluation Threshold (AET), and no elements with concentrations higher than element-specific PDE (µg/day) were detected. NE'X Glue Surgical Adhesive is a versatile and promising new surgical sealant with a wide range of potential applications and very good biocompatibility.

THE USE OF SURGICAL ADHESIVE AND SUTURE FIXING MESHES TO THE ABDOMINAL WALL: AN EXPERIMENTAL STUDY IN RATS

AIM

Proper fixation of the surgical mesh determines the success of a herniorrhaphy. Understanding the inflammatory response and the mechanical properties of the mesh helps to define whether a fixation method is superior. This study aimed to evaluate the healing of defects in the abdominal wall of rats, comparing the repair of macroporous polypropylene meshes fixed with surgical glue and polypropylene thread.

METHODS

In 20 Wistar rats, a defect was produced in the abdominal wall, with the integrity of the parietal peritoneum. For correction, the meshes were fixed with surgical glue (2-octyl cyanoacrylate) (subgroup C1), or polypropylene suture (subgroup C2). The two subgroups of 10 animals were euthanized on the 90th postoperative day, and the fragments of the abdominal wall were submitted to macroscopic, histological, and tensiometric analysis.

RESULTS

Macroscopic analysis did not show any abnormalities. Tensiometry on the 90th postoperative day in subgroup C1 showed mean rupture tension of 28.47N and in subgroup C2 32.06N (p=0.773). The inflammatory process score revealed that both groups are in the subacute phase (p=0.380).

CONCLUSION

The fixation of a polypropylene macroporous mesh to repair an abdominal wall defect can be performed with surgical glue (2-octyl cyanoacrylate) or polypropylene suture, both methods being equally effective.

Biodegradable and Biocompatible Adhesives for the Effective Stabilisation, Repair and Regeneration of Bone

Bone defects and complex fractures present significant challenges for orthopaedic surgeons. Current surgical procedures involve the reconstruction and mechanical stabilisation of complex fractures using metal hardware (i.e., wires, plates and screws). However, these procedures often result in poor healing. An injectable, biocompatible, biodegradable bone adhesive that could glue bone fragments back together would present a highly attractive solution. A bone adhesive that meets the many clinical requirements for such an application has yet to be developed. While synthetic and biological polymer-based adhesives (e.g., cyanoacrylates, PMMA, fibrin, etc.) have been used effectively as bone void fillers, these materials lack biomechanical integrity and demonstrate poor injectability, which limits the clinical effectiveness and potential for minimally invasive delivery. This systematic review summarises conventional approaches and recent developments in the area of bone adhesives for orthopaedic applications. The required properties for successful bone repair adhesives, which include suitable injectability, setting characteristics, mechanical properties, biocompatibility and an ability to promote new bone formation, are highlighted. Finally, the potential to achieve repair of challenging bone voids and fractures as well as the potential of new bioinspired adhesives and the future directions relating to their clinical development are discussed.

Formaldehyde Release From Eyelash Glues: Analysis Using the Chromotropic Acid Method

BACKGROUND

Popularity of eyelash enhancements has increased dramatically. Eyelash enhancements are available as an over-the-counter consumer product with glue included and as a professional product where proprietary glues are typically used. Both types of eyelash extension glues may release formaldehyde despite not being declared as an ingredient. Although formaldehyde is a carcinogen and may cause allergic contact dermatitis, few studies have assessed its presence in eyelash glues.

OBJECTIVE

The aim of the study was to evaluate professional and consumer eyelash glues for the presence of formaldehyde using the chromotropic acid method (CAM).

METHODS

A total of 37 eyelash glues were evaluated: 17 consumer eyelash glues (2 of which declared formaldehyde) and 20 professional eyelash glues (none of which declared formaldehyde) were purchased and analyzed with the CAM of testing.

RESULTS

For consumer eyelash glues, the 2 glues that declared formaldehyde were positive on CAM testing as well as 2 glues (13.3% [2/15]) that did not declare formaldehyde. Of the 20 professional eyelash glues, 15 (75.0%) were positive for formaldehyde.

CONCLUSIONS

Some consumer eyelash glues and most professional eyelash glues released formaldehyde when evaluated with CAM. Patients and clinicians should be aware that both consumer and professional eyelash glues can be sources of formaldehyde.

A Revolutionary, Proven Solution to Vascular Access Concerns: A Review of the Advantageous Properties and Benefits of Catheter Securement Cyanoacrylate Adhesives

Intravascular catheters are widely used among hospitals; however, their failure rates are high, up to 50%, when secured by traditional techniques, such as tape and gauze. The use of catheter securement cyanoacrylate adhesives provides a unique approach to the issues surrounding the use of traditional securement techniques for vascular access devices by providing significant securement strength, barrier properties, antibacterial properties, hemostatic properties, and flexibility. The purpose of this research was to perform a thorough and systematic review of the current literature existing regarding the use of cyanoacrylate adhesive for the care and maintenance of vascular access devices.

Emerging bioadhesives: from traditional bioactive and bioinert to a new biomimetic protein-based approach

Bioadhesives have reached significant milestones over the past two decades. Research has shown not only to produce adhesives capable of adhering to dry tissue but recently wet tissue as well. However, most bioadhesives developed have exhibited high adhesion strength yet lack other properties required for versatility in application, such as elasticity, biocompatibility and biodegradability. Adapting from limitations met from early bioadhesives and meeting the current demand allows novel bioadhesives to reach new milestones for the future. In this review, we overview the progression and variations of bioadhesives, current trends, characterisation techniques and conclude with future perspectives for bioadhesives for tissue engineering applications.

Adhesive Tissue Engineered Scaffolds: Mechanisms and Applications

A variety of suture and bioglue techniques are conventionally used to secure engineered scaffold systems onto the target tissues. These techniques, however, confront several obstacles including secondary damages, cytotoxicity, insufficient adhesion strength, improper degradation rate, and possible allergic reactions. Adhesive tissue engineering scaffolds (ATESs) can circumvent these limitations by introducing their intrinsic tissue adhesion ability. This article highlights the significance of ATESs, reviews their key characteristics and requirements, and explores various mechanisms of action to secure the scaffold onto the tissue. We discuss the current applications of advanced ATES products in various fields of tissue engineering, together with some of the key challenges for each specific field. Strategies for qualitative and quantitative assessment of adhesive properties of scaffolds are presented. Furthermore, we highlight the future prospective in the development of advanced ATES systems for regenerative medicine therapies.

Soft Electronic Materials with Combinatorial Properties Generated via Mussel-Inspired Chemistry and Halloysite Nanotube Reinforcement

Soft and electrically active materials are currently being utilized for intelligent systems, including electronic skin, cybernetics, soft robotics, and wearable devices. However, fabricating materials that fulfill the complex requirements of such advanced applications remains a challenge. These attributes include electronic, adhesive, self-healing, flexible, moldable, printable, and strong mechanical properties. Inspired by the recent interest in transforming monofunctional materials into multifunctional ones through nanoreinforcement and mussel-inspired chemistry, we have designed a simple two-step methodology based on halloysite nanotube (HNT) and polydopamine (PDA) to address the grand challenges in the field. In brief, HNTs were coated with PDA and embedded within a poly(vinyl alcohol) (PVA)-based polymeric matrix in combination with ferric ions (Fe³⁺). The final composite displayed a 3-fold increase in electrical conductivity, a 20-fold increase in mechanical stiffness, and a 7-fold increase in energy dissipation in comparison to their nonfunctional counterparts, which arose from a combination of nanotube alignment and mussel-inspired chemistry. Moreover, the developed composite could elongate up to 30000% of its original length, maintain its electrical properties after 600% strain, self-heal within seconds (both electrically and mechanically), and display strain-sensitivity. Finally, it was 3D-printable and thus amenable for engineering of customized wearable electronics.

Electrospun meshes of poly (n-butyl cyanoacrylate) and their potential applications for drug delivery and tissue engineering

The aim of the present work was to develop novel meshes of poly (n-butyl cyanoacrylate) (PBCA) nanofibers for potential applications in drug delivery and tissue engineering taking into account the successful application of PBCA in other medical uses. Electrospinning was applied to solutions of PBCA, 10³ and 10⁶ Da. 5-fluorouracil was chosen as model drug for the delivery study because of its effectiveness against cancer, while human gingival fibroblasts (HFIB-G) to confirm the biocompatibility of drug-free PBCA meshes and their potential for tissue engineering. PBCA was able to be electrospun in a wide range of molecular weights, producing fibers free of defects with diameters between 380 nm and 6 μm. Meshes of PBCA (10⁵-10⁶ Da) showed high flexibility with Younǵs modulus and maximal tension values in the range of 0.3-1.6 MPa and 0.03-0.13 MPa respectively. Results from the drug delivery study suggested that 5-fluorouracil was homogeneously loaded into PBCA meshes. Its release was extremely slow, initially 20% in 7 days and the rest gradually (until 96 days) in physiological medium at 37 °C. HFIB-G were well attached and proliferated over PBCA nanofibers during 23 days. Results suggested that PBCA meshes serve as excellent frameworks for cell adhesion/proliferation, and for drug delivery extended periods.

Inguinal Hernia: Defect Obliteration with the 3D Dynamic Regenerative Scaffold Proflor™

Prosthetic inguinal hernia repair presents significant challenges. Some of these, such as mesh fixation and quality of the biologic response, are still debated among surgeons. For example, there is no strong consensus regarding a specific condition that characterizes the surgical procedure during herniorrhaphy. This issue concerns management of the hernia defect, which in conventional hernia repair with flat meshes remains patent. However, a critical analysis of typical postoperative complications after inguinal hernia repair reveals that some of these adverse events are related to patency of the hernial opening. Postoperative discomfort, pain with specific movements and even hernia recurrence can be caused by incomplete or defective management of the hernia defect. For this reason, a deeper understanding of this topic would be useful for improving postoperative outcomes. A recently updated concept for inguinal hernia repair takes this technical aspect into consideration. It is based on the use of a newly developed 3D scaffold-ProFlor™ (Insightra Medical, Inc., Clarksville, TN, USA)-that is intended to be deployed into the defect. This novel hernia repair device has interesting and original features, such as dynamic responsivity in compliance with inguinal movement, fixation-free mode and regenerative behavior that counteracts the degenerative effects of the disease. Another additional proprietary feature of this 3D scaffold is the full and permanent obliteration of the defect, which is a crucial aspect to improve outcomes by avoiding the typical adverse effects of this surgical procedure. Obliteration of the hernia defect with the 3D dynamic regenerative scaffold ProFlor™ appears to be superior to coverage by means of static (passive) flat meshes/plugs used in conventional hernia repair. This report highlights the principles of this procedural approach.

Polymeric Tissue Adhesives

Polymeric tissue adhesives provide versatile materials for wound management and are widely used in a variety of medical settings ranging from minor to life-threatening tissue injuries. Compared to the traditional methods of wound closure (i.e., suturing and stapling), they are relatively easy to use, enable rapid application, and introduce minimal tissue damage. Furthermore, they can act as hemostats to control bleeding and provide a tissue-healing environment at the wound site. Despite their numerous current applications, tissue adhesives still face several limitations and unresolved challenges (e.g., weak adhesion strength and poor mechanical properties) that limit their use, leaving ample room for future improvements. Successful development of next-generation adhesives will likely require a holistic understanding of the chemical and physical properties of the tissue-adhesive interface, fundamental mechanisms of tissue adhesion, and requirements for specific clinical applications. In this review, we discuss a set of rational guidelines for design of adhesives, recent progress in the field along with examples of commercially available adhesives and those under development, tissue-specific considerations, and finally potential functions for future adhesives. Advances in tissue adhesives will open new avenues for wound care and potentially provide potent therapeutics for various medical applications.

β-Cyclodextrin/Triclosan Complex-Grafted Methacrylated Glycol Chitosan Hydorgel by Photocrosslinking via Visible Light Irradiation for a Tissue Bio-Adhesive

Accelerating wound healing with minimized bacterial infection has become a topic of interest in the development of the new generation of tissue bio-adhesives. In this study, we fabricated a hydrogel system (MGC-g-CD-ic-TCS) consisting of triclosan (TCS)-complexed beta-cyclodextrin (β-CD)-conjugated methacrylated glycol chitosan (MGC) as an antibacterial tissue adhesive. Proton nuclear magnetic resonance (1H NMR) and differential scanning calorimetry (DSC) results showed the inclusion complex formation between MGC-g-CD and TCS. The increase of storage modulus (G') of MGC-g-CD-ic-TCS after visible light irradiation for 200 s indicated its hydrogelation. The swollen hydrogel in aqueous solution resulted in two release behaviors of an initial burst and sustained release. Importantly, in vitro and in vivo results indicated that MGC-g-CD-ic-TCS inhibited bacterial infection and improved wound healing, suggesting its high potential application as an antibacterial tissue bio-adhesive.

Chronic rhinosinusitis due to cyano-acrylic glue after endoscopic transsphenoidal pituitary surgery

Background

To reduce the risk of cerebrospinal fluid leak, clinicians utilize a filling material placed in the sella followed by floor reconstruction with various materials, including glue sealing. Cyano-acrylic glue Glubran®2 glue is commercially available and is generally used as embolizing agent and for the prevention of cerebrospinal fluid leakage.

Case Description

A 25-year-old woman underwent endoscopic endonasal transsphenoidal surgery for pituitary adenoma. After tumor resection, sellar floor reconstruction was performed by mucosal graft and Glubran®2 glue. The early post-operative period was uneventful. However, 2 months after surgery, the patient complained of headache, facial pain and greenish foul-smelling nasal discharge with solid particles dripping from the nose. Medical treatment was unsuccessful. Brain MRI showed inflammation and thickening of the sphenoidal and para-sphenoidal mucosa. The patient underwent endoscopic endonasal surgery and a solid glass-like mass surrounded by inflamed infected mucosa was seen in the inferior and lateral aspects of the sphenoid sinus. Efforts were made to erupt and de-crust the solid mass until total resection was achieved. Early post-operative period was uneventful, and a course of antibiotics was continued until total disappearance of the discharge.

Conclusion

To the best of our knowledge, this is the first case reporting of acrylic glue (Glubran®2)-related sinusitis. Surgeon should be aware about similar side effects for the glue material that would complicate the surgery.

Analysis of resorbable mesh implants in short-term human muscular fascia cultures: a pilot study

PURPOSE

Alteration in fascial tissue collagen composition represents a key factor in hernia etiology and recurrence. Both resorbable and non-resorbable meshes for hernia repair are currently used in the surgical setting. However, no study has investigated so far the role of different implant materials on collagen deposition and tissue remodeling in human fascia. The aim of the present study was to develop a novel ex vivo model of human soft tissue repair mesh implant, and to test its suitability to investigate the effects of different materials on tissue remodeling and collagen composition.

METHODS

Resorbable poly-4-hydroxybutyrate and non-resorbable polypropylene mesh implants were embedded in human abdominal fascia samples, mimicking common surgical procedures. Calcein-AM/Propidium Iodide vital staining was used to assess tissue vitality. Tissue morphology was evaluated using Mallory trichrome and hematoxylin and eosin staining. Collagen type I and III expression was determined through immunostaining semi-quantification by color deconvolution. All analyses were performed after 54 days of culture.

RESULTS

The established ex vivo model showed good viability at 54 days of culture, confirming both culture method feasibility and implants biocompatibility. Both mesh implants induced a disorganization of collagen fibers pattern. A statistically significantly higher collagen I/III ratio was detected in fascial tissue samples cultured with resorbable implants compared to either non-resorbable implants or meshes-free controls.

CONCLUSION

We developed a novel ex vivo model and provided evidence that resorbable polyhydroxybutyrate meshes display better biomechanical properties suitable for proper restoration in surgical hernia repair.

Retrospective Evaluation of the Effectiveness of a Synthetic Glue and a Fibrin-Based Sealant for the Prevention of Seroma Following Axillary Dissection in Breast Cancer Patients

Introduction: Seroma formation represents one of the most frequent postoperative complications of axillary dissection in breast cancer (BC) patients. We aimed to retrospectively explore the effectiveness of the intraoperative use of a synthetic cyanoacrylate glue (specifically Glubran®2) vs. the intraoperative use of a fibrin sealant (specifically Tisseel) in reducing seroma formation compared to the use of nonsealant in BC patients who underwent breast surgery and axillary dissection. Materials and Methods: We conducted a retrospective, monocentric observational study on BC patients who underwent axillary dissection associated with breast surgery. The axillary dissection was completed with the application of a closed suction drain and was preceded by the application of either Glubran®2 glue or Tisseel sealant or nonsealant. We analyzed the quantity of serum drained in the first 3 postoperative days, length of hospitalization, days of permanence of axillary drain, seroma development, and presence of postoperative infection signs. Results: Forty-one BC patients were considered. Based on the device used during the surgical treatment, the patients were divided into three groups: group A (17 patients), to whom suction axillary drain was applied; group B (7 patients), to whom Tisseel and axillary suction drain were applied; and group C (17 patients), to whom Glubran®2 and axillary suction drain were applied. Among the three groups, we did not find significant differences in terms of amount of serum drained in the first 3 postoperative days, length of hospitalization, and incidence of seroma. Group C maintained the axillary drain in a significantly lower number of days compared to the other two groups (p = 0.02); it also had a lower incidence of postoperative infections (6%) compared to group A (23%) and group B (57%) (p = 0.02). Conclusions: We did not find any evidence that the use of surgical glues may reduce the formation of seroma following axillary dissection in BC patients. Nevertheless, the use of cyanoacrylate glue in association with closed suction axillary drain seems to contribute to the reduction in days of axillary drain permanence and of postoperative infections, which are known factors delaying the schedule of any adjuvant oncological therapies.

Thermo-Responsive Antimicrobial Hydrogel for the In-Situ Coating of Mesh Materials for Hernia Repair

The prophylactic coating of prosthetic mesh materials for hernia repair with antimicrobial compounds is commonly performed before implantation of the mesh in the abdominal wall. We propose a novel alternative, which is a rifampicin-loaded thermo-responsive hydrogel formulation, to be applied on the mesh after its implantation. This formulation becomes a gel in-situ once reached body temperature, allowing an optimal coating of the mesh along with the surrounding tissues. In vitro, the hydrogel cytotoxicity was assessed using rabbit fibroblasts and antimicrobial efficacy was determined against Staphylococcus aureus. An in vivo rabbit model of hernia repair was performed; implanted polypropylene meshes (5 × 2 cm) were challenged with S. aureus (10⁶ CFU), for two study groups—unloaded (n = 4) and 0.1 mg/cm² rifampicin-loaded hydrogel (n = 8). In vitro, antibacterial activity of the hydrogel lasted for 5 days, without sign of cytotoxicity. Fourteen days after implantation, meshes coated with drug-free hydrogel developed a strong infection and resulted in poor tissue integration. Coating meshes with the rifampicin-loaded hydrogel fully prevented implant infection and permitted an optimal tissue integration. Due to its great performance, this, degradable, thermo-responsive antimicrobial hydrogel could potentially be a strong prophylactic armamentarium to be combined with prosthesis in the surgical field.

The recent progress of tissue adhesives in design strategies, adhesive mechanism and applications

Tissue adhesives have emerged as an effective method for wound closure and hemostasis in recent decades, due to their ability to bond tissues together, preventing separation from one tissue to another. However, existing tissue adhesives still have several limitations. Tremendous efforts have been invested into developing new tissue adhesives by improving upon existing adhesives through different strategies. Therefore, highlighting and analyzing these design strategies are essential for developing the next generation of advanced adhesives. To this end, we reviewed the available strategies for modifying traditional adhesives (including cyanoacrylate glues, fibrin sealants and BioGlue), as well as design of emerging adhesives (including gelatin sealants, methacrylated sealants and bioinspired adhesives), focusing on their structures, adhesive mechanisms, advantages, limitations, and current applications. The bioinspired adhesives have numerous advantages over traditional adhesives, which will be a wise direction for achieving tissue adhesives with superior properties.

The cytotoxic properties and apoptotic potential of N-butyl and 2-octyl cyanoacrylates used in surgical treatment of chronic venous insufficiency

Background

This study aims to investigate the cytotoxic effects and apoptotic potential of N-butyl cyanoacrylate and 2-octyl cyanoacrylate used in surgical treatment of chronic venous insufficiency.

Methods

N-butyl cyanoacrylate and 2-octyl cyanoacrylate were cultured in cell-culture using human umbilical endothelial cell-line. Cytotoxicity and viability were assessed at 24 and 72 hours with lactate dehydrogenase and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, respectively. Apoptotic potential was documented at 24 and 72 hours with relative caspase-3 activity.

Results

The mean cytotoxicity at 24 and 72 hours were: N-butyl cyanoacrylate with an area of dot/line: 37.0±3.9%/29.3±2.7% and 46.4±1.6%/45.1±7.1%, 2-octyl cyanoacrylate with an area of dot/line: 39.0±7.0%/37.3±4.6% and 47.0±2.3%/40.7±7.5%. Cytotoxicity increased by time in each group (p<0.05). The mean viability at 24 and 72 hours were: N-butyl cyanoacrylate with an area of dot/line: 53.4±7.7%/72.0±5.7% and 35.7±1.9%/37.8±3.7%, 2-octyl cyanoacrylate with an area of dot/line: 54.3±4.4%/73.5±19.9% and 33.6±2.8%/30.7±4.5%. The mean viability decreased by time in each group (p<0.05). The mean relative caspase-3 activity at 24 and 72 hours were: control group: 0.084±0.006 and 0.065±0.002, N-butyl cyanoacrylate with an area of dot/line: 0.940±0.037/0.924±0.053 and 0.999±0.072/1.056±0.015, 2-octyl cyanoacrylate with an area of dot/line: 0.900±0.044/0.928±0.018 and 0.989±0.084/0.999±0.072. The mean relative caspase-3 activity was higher than control group in each group at each time interval (p<0.05) and activity increased by time in N-butyl cyanoacrylate line and in 2-octyl cyanoacrylate line groups (p<0.05).

Conclusion

Our findings indicate that N-butyl cyanoacrylate and 2-octyl cyanoacrylate cause cytotoxicity in cell-culture media. We may also postulate that they induce apoptosis in cell-culture media.

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.

Bioionic Liquid Conjugation as Universal Approach To Engineer Hemostatic Bioadhesives

Adhesion to wet and dynamic surfaces is vital for many biomedical applications. However, the development of effective tissue adhesives has been challenged by the required combination of properties, which includes mechanical similarity to the native tissue, high adhesion to wet surfaces, hemostatic properties, biodegradability, high biocompatibility, and ease of use. In this study, we report a novel bioinspired design with bioionic liquid (BIL) conjugated polymers to engineer multifunctional highly sticky, biodegradable, biocompatible, and hemostatic adhesives. Choline-based BIL is a structural precursor of the phospholipid bilayer in the cell membrane. We show that the conjugation of choline molecules to naturally derived polymers (i.e., gelatin) and synthetic polymers (i.e., polyethylene glycol) significantly increases their adhesive strength and hemostatic properties. Synthetic or natural polymers and BILs were mixed at room temperature and cross-linked via visible light photopolymerization to make hydrogels with tunable mechanical, physical, adhesive, and hemostatic properties. The hydrogel adhesive exhibits a close to 50% decrease in the total blood volume loss in tail cut and liver laceration rat animal models compared to the control. This technology platform for adhesives is expected to have further reaching application vistas from tissue repair to wound dressings and the attachment of flexible electronics.

Rapid Self-Assembly of Bioengineered Cardiovascular Bypass Grafts From Scaffold-Stabilized, Tubular Bilevel Cell Sheets

BACKGROUND

Cardiovascular bypass grafting is an essential treatment for complex cases of atherosclerotic disease. Because the availability of autologous arterial and venous conduits is patient-limited, self-assembled cell-only grafts have been developed to serve as functional conduits with off-the-shelf availability. The unacceptably long production time required to generate these conduits, however, currently limits their clinical utility. Here, we introduce a novel technique to significantly accelerate the production process of self-assembled engineered vascular conduits.

METHODS

Human aortic smooth muscle cells and skin fibroblasts were used to construct bilevel cell sheets. Cell sheets were wrapped around a 22.5-gauge Angiocath needle to form tubular vessel constructs. A thin, flexible membrane of clinically approved biodegradable tissue glue (Dermabond Advanced) served as a temporary, external scaffold, allowing immediate perfusion and endothelialization of the vessel construct in a bioreactor. Subsequently, the matured vascular conduits were used as femoral artery interposition grafts in rats (n=20). Burst pressure, vasoreactivity, flow dynamics, perfusion, graft patency, and histological structure were assessed.

RESULTS

Compared with engineered vascular conduits formed without external stabilization, glue membrane-stabilized conduits reached maturity in the bioreactor in one-fifth the time. After only 2 weeks of perfusion, the matured conduits exhibited flow dynamics similar to that of control arteries, as well as physiological responses to vasoconstricting and vasodilating drugs. The matured conduits had burst pressures exceeding 500 mm Hg and had sufficient mechanical stability for surgical anastomoses. The patency rate of implanted conduits at 8 weeks was 100%, with flow rate and hind-limb perfusion similar to those of sham controls. Grafts explanted after 8 weeks showed a histological structure resembling that of typical arteries, including intima, media, adventitia, and internal and external elastic membrane layers.

CONCLUSIONS

Our technique reduces the production time of self-assembled, cell sheet-derived engineered vascular conduits to 2 weeks, thereby permitting their use as bypass grafts within the clinical time window for elective cardiovascular surgery. Furthermore, our method uses only clinically approved materials and can be adapted to various cell sources, simplifying the path toward future clinical translation.

Designing a castor oil-based polyurethane as bioadhesive

Based on the stealth behavior of castor oil and poly(ethylene glycol), we selected a polyurethane system to obtain an ideal surgical adhesive. The polyurethane adhesives with varying concentrations of castor oil were investigated by Fourier transform infrared spectrometer, differential scanning calorimetry, scanning electron microscopy, goniometer, and universal testing machine. Curing results show that a 7-min to 25-min room temperature curing can be achieved, providing one possibility of shortening the surgery time. In vitro biodegradation test demonstrates that a certain proportion of the polyurethane film will be hydrolyzed in a foregone manner after a period of time (7 weeks). The adhesion strengths of these adhesives show a strong bonding between pieces of tissue, which makes them qualified for application in a moist environment.

Evaluation of Regular Market Ethyl Cyanoacrylate Cytotoxicity for Human Gingival Fibroblasts and Osteoblasts

Background: The aim of this study was to evaluate the cytotoxicity of cyanoacrylate adhesives in an indirect contact assay in human gingival fibroblast (FGH) and oral osteoblasts (GO) lineages. Methods: Cover glasses were glued with adhesives following the ISO 10993-2012 protocol. The groups were: C (control with cells and regular Dulbecco Modified Eagle Medium; LC (liquid ethyl-cyanoacrylate); GC (ethyl-cyanoacrylate gel); EGC (easy gel [ethyl-cyanoacrylate]); and D (Dermabond [octyl-cyanoacrylate]). Each cell linage was plated in the sixth passage using 10⁴ cells. Cell viability was measured by the MTT test at 24, 48, 72, and 96 hours. Data were analyzed by two-way analysis of variance complemented by the Tukey test, with p < 0.05 being significant. Results: Dermabond stimulated osteoblast viability at 72 h (p < 0.05). All other groups were similar to the control cells (p > 0.05). For the fibroblasts, there was no difference in the groups, including the control except that EGC was cytotoxic for these cells (p < 0.05). Conclusions: Ethyl-cyanoacrylate gel and liquid forms available on the general chemical market were not cytotoxic for oral osteoblasts and fibroblasts in most cases. However, the easy gel form was cytotoxic for fibroblasts.

Mesh fixation using novel bio-adhesive coating compared to tack fixation for IPOM hernia repair: in vivo evaluation in a porcine model

BACKGROUND

Mesh fixation in hernia repair is currently based on penetrating sutures or anchors, with proven early and late complications such as pain, adhesions, erosions, and anchor migration. In an attempt to reduce these complications, a bio-adhesive-based self-fixation system was developed. The purpose of this study was to assess the performance and safety of this novel self-adhesive mesh (LifeMesh™) by comparing it with standard tack fixation.

METHODS

A full-thickness abdominal wall defect was created bilaterally in 24 pigs. The defects were measured 14 days later, and laparoscopic intraperitoneal onlay mesh (IPOM) repairs were performed. In each animal, both LifeMesh and a titanium tack-fixed control, either uncoated polypropylene mesh (PP) or composite mesh (Symbotex™), were used. After 28 and 90 days, we performed macroscopic evaluation and analyzed the fixation strength, shrinkage, adhesion scores, and histopathology in all samples.

RESULTS

Measurements at both time points revealed that LifeMesh had fully conformed to the abdominal wall, and that its fixation strength was superior to that of the tack-fixated Symbotex and comparable to that of the tack-fixated PP. Shrinkage in all groups was similar. Adhesion scores with LifeMesh were lower than with PP and comparable with Symbotex at both time points. Histology demonstrated similar tissue responses in LifeMesh and Symbotex. Lack of necrosis, mineralization, or exuberant inflammatory reaction in all three groups pointed to their good progressive integration of the mesh to the abdominal wall. By 28 days the bio-adhesive layer in LifeMesh was substantially degraded, allowing a gradual tissue ingrowth that became the main fixation mode of this mesh to the abdominal wall.

CONCLUSIONS

The excellent incorporation of LifeMesh to the abdominal wall and its superior fixation strength, together with its low adhesion score, suggest that LifeMesh may become a preferred alternative for abdominal wall repair.

Histological analysis of biocompatibility of different surgical adhesives in subcutaneous tissue

The focus of this study was to test the hypothesis that there would be no difference between the biocompatibility of cyanoacrylate-based adhesives in rat subcutaneous tissues. In total, 60 male Wistar rats were used, and divided into four groups (n = 15): Group C (control, PVA-polyvinyl alcohol sponge), Group NO (N-butyl-2-octylcyanoacrylate), Group NH (n-hexyl-cyanoacrylate), and Group EC (Ethyl-cyanoacrylate). The animals were sacrificed after time intervals of 7, 15, and 30 days and tissues were analyzed under optical microscope as regards the events of inflammatory infiltrate, edema, necrosis, granulation tissue, giant cells, young fibroblasts, and collagen formation. The results were statistically analyzed by the Kruskal-Wallis and Dunn tests (p < .05). Significant inflammatory infiltrate was shown for all the adhesives in the time intervals of 7 (p = .004) and 15 days (p = .003). In the time interval of 30 days, moderate inflammatory infiltrate was observed in Groups NH and EC, with significant difference from Control (p = .001). The quantity of collagen fibers in all the experimental groups showed significant difference compared with Control in the time intervals of 7 (p = .002) and 15 days (p = .001), at 30 days only Group EC showed a smaller quantity of collagen fibers in comparison with Control (p = .001). The hypothesis was rejected. The adhesive N-butyl-2-octylcyanoacrylate had less influence on the inflammatory intensity of multinucleated giant cells. Ethyl-cyanoacrylate demonstrated the lowest level of biocompatibility among the adhesives, but its use in clinical practice may be promising for coaptation of smaller edges of superficial tissue. Surgical adhesives were shown to be feasible for clinical use in substitution of conventional suturing. Ethyl-cyanoacrylate should be used with caution due to its greater influence on tissues.

Biodegradability and Safety Study of LifeMesh™, a Novel Self-adhesive Mesh, in Sprague-Dawley Rats

Self-adhesive meshes are being developed to avoid complications due to traumatic fixation methods. LifeMesh™ is a novel self-adhesive mesh with a biodegradable gelatin adhesive layer developed for hernia repair. The aim of this study was to assess the safety and biodegradability of LifeMesh in Sprague-Dawley (SD) rats for 6 weeks, in comparison to a bare polypropylene (BPP) mesh fixed with sutures. LifeMesh was tolerated well and its implantation did not result in any adverse local reaction, and its adhesive layer was substantially degraded after 4 weeks. Histopathological examination revealed that the presence of the adhesive contributed to a uniform thickness of the granulation tissue surrounding the mesh, in contrast to a nonuniform granulation tissue with BPP. Nonuniform granulation tissue suggests that there will be poorer integration of the mesh to the abdominal wall. The use of LifeMesh also resulted in less adhesions of internal organs with a smaller surface area of involvement. These findings lend support to the potential benefit of LifeMesh for hernia repair in humans and expand the available information on the typical histopathological findings expected with biodegradable implants in the peritoneal cavity of SD rats.

Investigation of surgical adhesives for vocal fold wound closure

OBJECTIVES

Surgical adhesives are increasingly used for vocal fold microsurgery to assist wound closure and reduce the risks of scar formation. Currently used vocal fold adhesives such as fibrin glue, however, have thus far not been found to promote wound closure or reduce scarring. The objectives of this study were to investigate the mechanical strength and the cytotoxicity of three commercially available adhesives (Glubran 2, GEM, Viareggio, Italy; BioGlue, CryoLife, Kennesaw, GA; and Tisseel, Baxter Healthcare, Deerfield, IL) for vocal fold wound closure.

METHODS

Shear and tension tests were performed on 150 porcine larynges. The cytotoxicity of the adhesives to immortalized human vocal fold fibroblasts was investigated using neutral red uptake assays.

RESULTS

The average shear adhesive strength for Tisseel, BioGlue, and Glubran 2 was 13.86 ± 5.03 kilopascal (kPa), 40.92 ± 17.94 kPa, and 68.79 ± 13.29 kPa, respectively. The tensile adhesive strength for Tisseel, BioGlue, and Glubran 2 was 10.70 ± 6.42 kPa, 34.27 ± 12.59 kPa, and 46.67 ± 12.13 kPa, respectively. The vocal fold cell viabilities in extracts of Tisseel, BioGlue, and Glubran 2 were 99.27%, 43.05%, and 1.79%, respectively.

CONCLUSION

There was a clear tradeoff between adhesive strength and toxicity. The maximum failure strength in shear or tension of the three surgical adhesives ranked from strongest to the weakest was: 1) Glubran 2, 2) BioGlue, and 3) Tisseel. Tisseel was found to be the least toxic of the three adhesives, whereas Glubran 2 was the most toxic.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2139-2146, 2019.

Use of cyanoacrylate adhesive in the surgical management of feline corneal sequestrum: 16 cases (2011-2018)

OBJECTIVE

To evaluate the use of cyanoacrylate adhesive as an adjunct to lamellar keratectomy in cats with corneal sequestrum.

METHODS

Medical records were reviewed to identify cats with naturally occurring midstromal corneal sequestra treated with lamellar keratectomy and cyanoacrylate adhesive. All cats also had a bandage contact lens placed for postoperative comfort. Data collected included breed, age, sex, and reproductive status of the cat, eye involved, presence or absence of neovascularization at the time of surgery, history of prior sequestra, additional ocular procedures performed, use of neuromuscular blocking agents, procedure time, time to cessation of topical medications, time to recurrence or last follow-up, and complications aside from recurrence.

RESULTS

Sixteen cats met study criteria, with a median follow-up time of 17.5 months in those without recurrence. Median time to cessation of topical medications was 4 weeks. Fourteen cats (87%) have not experienced recurrence. Other than recurrence in two cats, no significant complications were noted. Aside from purebred status, no commonalities were found between the two cats with recurrence. Neuromuscular blocking agents were not used during surgery in most cases. Median procedure time was 10 minutes.

CONCLUSIONS

Cyanoacrylate adhesive is an effective and safe alternative to grafting procedures in cats undergoing lamellar keratectomy for treatment of corneal sequestrum. Recurrence rates are comparable to those seen with grafting techniques. Benefits of this approach include decreased anesthesia time, lower procedure costs, and short duration of postoperative treatment.

Clinical Feasibility of Large Gastrotomy Closure Using a Flexible Tissue Glue Based on N-Butyl-2-Cyanoacrylate: Experimental Study in Pigs

BACKGROUND

The use of synthetic adhesives such as cyanoacrylates has been established previously for a wide range of clinical indications. However, more research is necessary to evaluate their use in digestive closures or anastomosis. New chemical formulations developed to achieve more flexibility of synthetic adhesives (i.e., based on n-butyl-2-cyanoacrylate) could be an alternative to achieve this purpose. The aim of this study was to investigate the feasibility of using flexible cyanoacrylate adhesives for large gastric incision closure in an animal model.

METHODS

Twelve farm pigs were divided in two groups depending on the type of closure method applied. In all cases, extra-large seven centimeters gastrostomies were performed. Braided absorbable hand-sewn interrupted suture versus n-butyl-2-cyanoacrylate with softener closure were compared during a 3-week follow-up period. Histopathological aspects, hematologic and inflammatory biomarkers, and endoluminal pressure tolerated until leakage were assessed. The time spent on both closing procedures was compared.

RESULTS

No differences between the two groups were found in any of the histopathological and inflammatory variables evaluated. The glued group tolerated a significantly higher pressure than the manual suture group. A reduction of surgery time was also observed.

CONCLUSIONS

Our results suggest that flexible cyanoacrylates could be a feasible alternative to improve the clinical outcome of the closure of hollow viscera through more efficient sutureless procedures.

[Evaluation of the Cytotoxicity of Commercially Available Nail Adhesives]

Nail tips are nail art materials that can be attached to the nail with adhesives. Recently, nail/finger injuries related to nail tips have been reported and one of the causes is considered to be the adhesives used for attaching nail tips. The components of nail adhesives are mostly cyanoacrylate, which is also used as an industrial instant adhesive. During curing, cyanoacrylate adhesives release formaldehyde through hydrolysis. When it is marketed as a nail adhesive, there is no regulation regarding its formaldehyde amount nor obligation to indicate its ingredients in Japan. Additionally, a biological safety test is not required for nail adhesives. Thus, because the safety of nail adhesives is inadequately confirmed, it is necessary to investigate their biological safety. Therefore, we purchased 5 commercially available nail adhesives and 1 medical adhesive and examined their formaldehyde content and cytotoxicity. We examined the cytotoxicity of the adhesives in V79 cells by a colony forming assay. In this test, 5 nail adhesives showed higher toxicity than 1 medical adhesive. Formaldehyde concentrations in the extract of adhesives were as follows: 17.5 to 24.2 μg/mL for nail adhesives and 7.4 μg/mL for medical adhesives. Cyanoacetate did not elicit cytotoxicity at the final concentration up to 1000 μM. However, formaldehyde showed cytotoxicity, with an IC₅₀ of 79 μM (2.4 μg/mL). Taken together, the cytotoxicity of nail adhesives could be due to the formaldehyde generated by the hydrolysis of cyanoacrylate. It seems important that nail adhesives will be regulated by obligation and enhanced safety in the future.

Pre-clinical assay of the tissue integration and mechanical adhesion of several types of cyanoacrylate adhesives in the fixation of lightweight polypropylene meshes for abdominal hernia repair

INTRODUCTION

Lightweight (LW) polypropylene (PP) meshes better adapt to host tissue, causing less fibrosis and inflammatory responses than high-density meshes. Mesh fixation using tissue adhesives (TA) that replace conventional sutures may improve the process of hernia repair and tissue trauma. This preclinical study compares the behavior of different cyanoacrylate-based adhesives in the fixation of LW-PP meshes for hernia repair.

METHODS

Partial abdominal wall defects were repaired using LW-PP Optilene meshes in New Zealand rabbits. The following groups were established according to the mesh fixation method: Suture (control), Glubran 2 (n-butyl), Ifabond (n-hexyl), SafetySeal (n-butyl) and Evobond (n-octyl). At 14, 90 and 180 days after surgery, the recovered implants were examined to assess the host tissue integration, the macrophage response and the biomechanical strength.

RESULTS

All the groups showed optimal host tissue incorporation regardless of the fixation procedure. Significantly increased levels of collagen 1 and collagen 3 gene expression (p<0.001) were observed at 14 days compared to the medium- and long-term durations, where the Suture and Glubran groups showed the highest expression of collagen 1. All the adhesives increased the macrophage reaction (p<0.001) compared to sutures at all implant times. Maximal macrophage response was observed in the short-term Glubran group (p<0.01) compared to the rest of the groups. Although SafetySeal and Evobond did not reach the biomechanical resistance of sutures at 14 days, all the adhesives did reach this level in the medium- to long-term periods, providing significantly higher resistance (p<0.05).

CONCLUSIONS

All the cyanoacrylates, despite inducing a significantly increased macrophage response versus sutures, showed optimal host tissue integration and long-term mechanical behavior; thus, they might be good choices for LW-PP mesh hernia repairs.

Surface modification of polypropylene surgical meshes for improving adhesion with poloxamine hydrogel adhesive

Tissue adhesive has notable clinical benefits in hernia repair fixation. A novel poloxamine tissue adhesive was previously shown to successfully bond collagen tissue with adequate adhesive strength. In application related to attachment of polypropylene (PP) mesh, the adhesive strength between the mesh and poloxamine hydrogel adhesive is limited by the hydrophobicity of PP monofilaments and lack of covalent bond formation. The purpose of this study was to compare two different surface modifications [bovine serum albumin (BSA) adsorption and poly-glycidyl methacrylate/human serum albumin (PGMA/HSA) grafting] of PP mesh for improving the adhesive strength between poloxamine hydrogel adhesive and PP mesh. The PGMA/HSA surface modification significantly improved the adhesive strength for meshes attached with poloxamine hydrogel tissue adhesive compared with unmodified meshes and meshes modified by BSA adsorption. An area of 1 cm² adhesive provided for a maximum adhesive strength of 65-70 kPa for meshes modified by PGMA/HSA, 4-13 kPa for meshes modified by BSA, and 22-45 kPa for unmodified meshes. Optical microscopy and infrared spectroscopy (FTIR) confirmed the improved adhesive strength was achieved through mechanical interlock of the hydrogel tissue adhesive into the PP mesh pores and chemical bonding of the albumin after successful PGMA/HSA grafting onto the PP monofilaments. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1047-1055, 2019.