Cyanoacrylate tissue sealant impairs tissue integration of macroporous mesh in experimental hernia repair

Laponite stabilized endogenous antibacterial hydrogel as wet-tissue adhesive

Clinical adhesives for suture-less wound closure remain the problem of poor biocompatibility, weak adhesive strength, and no endogenous antibacterial ability. Here, we designed a novel antibacterial hydrogel (CP-Lap hydrogel) consisting of chitosan and ε-polylysine after being modified with gallic acid (pyrogallol structure). The hydrogel was crosslinked by glutaraldehyde and Laponite via Schiff base and dynamic Laponite-pyrogallol interaction, free from heavy metal and oxidants. Given its dual crosslinking feature, the CP-Lap hydrogel exhibited adequate mechanical strength (150-240 kPa) and demonstrated swelling and degradation resistance. For a typical lap shear test with pigskin, the apparent adhesion strength of the CP-Lap hydrogel could be enhanced to ∼30 kPa benefiting from the O2 blocking effect provided by nanoconfinement space between Laponite. In addition, the hydrogel showed effective antibacterial properties and excellent biocompatibility. The results indicated that this hydrogel has great potential for wound-closing bioadhesives to avoid chronic infections and further harm.

Synthetic Pressure Sensitive Adhesives for Biomedical Applications

Pressure sensitive adhesives are components of everyday products found in homes, offices, industries, and hospitals. Serving the general purpose of fissure repair and object fixation, pressure sensitive adhesives indiscriminately bind surfaces, as long as contact pressure is administered at application. With that being said, the chemical and material properties of the adhesive formulation define the strength of a pressure sensitive adhesive to a particular surface. Given our increased understanding of the viscoelastic material requirements as well as the intermolecular interactions at the binding interface required for functional adhesives, pressure sensitive adhesives are now being explored for greater use. New polymer formulations impart functionality and degradability for both internal and external applications. This review highlights the structure-property relationships between polymer architecture and pressure sensitive adhesion, specifically for medicine. We discuss the rational, molecular-level design of synthetic polymers for durable, removable, and biocompatible adhesion to wet surfaces like tissue. Finally, we examine prevalent challenges in biomedical wound closure and the new, innovative strategies being employed to address them. We conclude by summarizing the progress of current research, identifying additional clinical opportunities, and discussing future prospects.

Acceleration of Oral Wound Healing under Diabetes Mellitus Conditions Using Bioadhesive Hydrogel

Oral wounds under diabetic conditions display a significant delay during the healing process, mainly due to oxidative stress-induced inflammatory status and abnormal immune responses. Besides, the wet and complicated dynamic environment of the oral cavity impedes stable treatment of oral wounds. To overcome these, a biomimetic hydrogel adhesive was innovatively developed based on a mussel-inspired multifunctional structure. The adhesive displays efficient adhesion and mechanical harmony on the oral mucosa through enhanced bonding in an acidic proinflammatory environment. The bioadhesive hydrogel exhibits excellent antioxidative properties by mimicking antioxidative enzymatic activities to reverse reactive oxygen species (ROS)-mediated immune disorders. Experiments on oral wounds of diabetic rats showed that this hydrogel adhesive could effectively protect against mucosal wounds and obviously shorten the inflammatory phase, thus promoting the wound-healing process. Therefore, this study offers a promising therapeutic choice with the potential to advance the clinical treatment of diabetic oral wounds.

Promoting Oral Mucosal Wound Healing with a Hydrogel Adhesive Based on a Phototriggered S-Nitrosylation Coupling Reaction

The wet and highly dynamic environment of the mouth makes local treatment of oral mucosal diseases challenging. To overcome this, a photo-crosslinking hydrogel adhesive is developed inspired by the success of light-curing techniques in dentistry. The adhesive operates on a fast (within 5 s) phototriggered S-nitrosylation coupling reaction and employs imine anchoring to connect to host tissues. Unlike other often-used clinical agents that adhere weakly and for short durations, this thin, elastic, adhesive, and degradable cyclic o-nitrobenzyl-modified hyaluronic acid gel protects mucosal wounds from disturbance by liquid rinsing, oral movement, and friction for more than 24 h. The results from both rat and pig oral mucosa repair models demonstrate that this new gel adhesive creates a favorable microenvironment for tissue repair and can shorten tissue healing time. This study thus illustrates a therapeutic strategy with the potential to advance the treatment of oral mucosal defects in the clinic.

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.

Developing a Hernia Mesh Tissue Integration Index Using a Porcine Model-A Pilot Study

Introduction: With so many prosthetics available, it can be difficult for surgeons to choose the most appropriate hernia mesh. Successful hernia repair mandates an understanding of how the patient's inflammatory response influences surgical outcomes. Failure to appreciate the importance of the biological aspect of hernia repair can be very costly as emerging evidence supports that biofilm formation and reduction in effective mesh porosity gives rise to long-term mesh complications including fibrosis, chronic mesh infection, and pain. In this pilot study, we utilized a large animal (porcine) model to develop a numerical Mesh Tissue Integration (MTI) Index focused on visible tissue ingrowth, fibrosis, adhesion formation and resorption of mesh. The aim is to help surgeons adopt an evidence-based approach in selecting the most appropriate mesh according to its tissue ingrowth characteristics, matched to the patient to achieve improved surgical outcomes and optimal patient-centered care.

Methods: Two forty kg female Landrace pigs were recruited for this pilot study. A total of eight commonly used hernia mesh products and two controls measuring 5 × 5cm were surgically implanted in subrectus and intraperitoneal planes. The pigs were euthanised at 2 and 4 weeks, respectively. The abdominal wall was explanted, and the mesh specimens underwent macroscopic, histologic and biomechanical analysis, with engineering and pathology teams blinded to the mesh.

Results: Significant differences between the degrees of MTI were observed at 2 weeks and the distinctions were even more apparent at 4 weeks. One of the interesting incidental findings we observed is that mesh products placed in the subrectus plane displayed greater degrees of adhesion strength and integration than those placed intraperitoneally.

Conclusion: This pilot study is one of the first to propose a functional, biological standardized model for comparing hernia mesh products. The results are encouraging and demonstrate that this is a robust and transferrable model for assessing MTI in hernia mesh. The intention for this model is that it will be utilized synergistically with long term mesh/patient outcome registries and databases to inform improved matching of mesh to patient, particularly in the setting of the complex hernia repair and abdominal wall reconstruction.

Recent Advances on Synthetic and Polysaccharide Adhesives for Biological Hemostatic Applications

Rapid hemostasis and formation of stable blood clots are very important to prevent massive blood loss from the excessive bleeding for living body, but their own clotting process cannot be completed in time for effective hemostasis without the help of hemostatic materials. In general, traditionally suturing and stapling techniques for wound closure are prone to cause the additional damages to the tissues, activated inflammatory responses, short usage periods and inevitable second operations in clinical applications. Especially for the large wounds that require the urgent closure of fluids or gases, these conventional closure methods are far from enough. To address these problems, various tissue adhesives, sealants and hemostatic materials are placed great expectation. In this review, we focused on the development of two main categories of tissue adhesive materials: synthetic polymeric adhesives and naturally derived polysaccharide adhesives. Research of the high performance of hemostatic adhesives with strong adhesion, better biocompatibility, easy usability and cheap price is highly demanded for both scientists and clinicians, and this review is also intended to provide a comprehensive summarization and inspiration for pursuit of more advanced hemostatic adhesives for biological fields.

In-vivo evaluation of the effect of cyanoacrylate on prosthetic vascular graft infection – does cyanoacrylate increase the severity of infection?

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.

Applications of Highly Stretchable and Tough Hydrogels

Stretchable and tough hydrogels have drawn a lot of attention recently. Due to their unique properties, they have great potential in the application in areas such as mechanical sensing, wound healing, and drug delivery. In this review, we will summarize recent developments of stretchable and tough hydrogels in these areas.

Multifunctional Biomedical Adhesives

Currently available biomedical adhesives are mainly engineered to have one function (i.e., providing mechanical support for the repaired tissue). To improve the performance of existing bioadhesives and broaden their applications in medicine, numerous multifunctional bioadhesives are reported in the literature. These adhesives can be categorized as passive or active by design. Passive multifunctional bioadhesives contain inherent compositions and structural designs that can carry out additional functions without added external influences. These adhesives exhibit new functionalities such as antimicrobial properties, self-healing abilities, the ability to promote cellular ingrowth, and the ability to be reshaped. Conversely, active multifunctional bioadhesives respond to environmental changes (e.g., pH, temperature, electricity, light, and biomolecule concentration), which initiate a change in the adhesive to release encapsulated drugs or to activate or deactivate the bioadhesive for interfacial binding. This review article highlights recent advances in multifunctional bioadhesives.

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.

Bioinspired Underwater Adhesives by Using the Supramolecular Toolbox

Nature has developed protein-based adhesives whose underwater performance has attracted much research attention over the last few decades. The adhesive proteins are rich in catechols combined with amphiphilic and ionic features. This combination of features constitutes a supramolecular toolbox, to provide stimuli-responsive processing of the adhesive, to secure strong adhesion to a variety of surfaces, and to control the cohesive properties of the material. Here, the versatile interactions used in adhesives secreted by sandcastle worms and mussels are explored. These biological principles are then put in a broader perspective, and synthetic adhesive systems that are based on different types of supramolecular interactions are summarized. The variety and combinations of interactions that can be used in the design of new adhesive systems are highlighted.

Host tissue response by the expression of collagen to cyanoacrylate adhesives used in implant fixation for abdominal hernia repair

The less traumatic use of surgical adhesives rather than sutures for mesh fixation in hernia repair has started to gain popularity because they induce less host tissue damage and provoke less postoperative pain. This study examines the host tissue response to a new cyanoacrylate (CA) adhesive (n-octyl, OCA). Partial defects (3 × 5 cm) created in the rabbit anterior abdominal wall were repaired by mesh fixation using OCA, Glubran2^®(n-butyl-CA), Ifabond^®(n-hexyl-CA) or sutures. Samples were obtained at 14/90 days for morphology, collagens qRT-PCR/immunofluorescence and biomechanical studies. All meshes were successfully fixed. Seroma was detected mainly in the Glubran group at 14 days. Meshes fixed using all methods showed good host tissue incorporation. No signs of degradation of any of the adhesives were observed. At 14 days, collagen 1 and 3 mRNA expression levels were greater in the suture and OCA groups, and lower in Ifabond, with levels varying significantly in the latter group with respect to the others. By 90 days, expression levels had fallen in all groups, except for collagen 3 mRNA in Ifabond. Collagen I and III protein expression was marked in the suture and OCA groups at 90 days, but lower in Ifabond at both time points. Tensile strengths were similar across groups. Our findings indicate the similar behavior of the adhesives to sutures in terms of good tissue incorporation of the meshes and optimal repair zone strength. The lower seroma rate and similar collagenization to controls induced by OCA suggests its improved behavior over the other two glues. This article deals with a preclinical study to examine different aspects of the repair process in the host of three alkyl cyanoacrylates (n-butyl (GLUBRAN 2), n-hexyl (IFABOND), and n-octyl cyanoacrylate (EVOBOND)) compared to sutures (control), in the fixation of surgical meshes for hernia repair. It goes into detail about collagen deposition in the repair zone at short and medium term. The results obtained demonstrate lower seroma rate and similar collagenization to sutures induced by the n-octyl suggesting better behavior than the other two cyanoacrylates.

Recent approaches in designing bioadhesive materials inspired by mussel adhesive protein

Marine mussels secret protein-based adhesives, which enable them to anchor to various surfaces in a saline, intertidal zone. Mussel foot proteins (Mfps) contain a large abundance of a unique, catecholic amino acid, Dopa, in their protein sequences. Catechol offers robust and durable adhesion to various substrate surfaces and contributes to the curing of the adhesive plaques. In this article, we review the unique features and the key functionalities of Mfps, catechol chemistry, and strategies for preparing catechol-functionalized polymers. Specifically, we reviewed recent findings on the contributions of various features of Mfps on interfacial binding, which include coacervate formation, surface drying properties, control of the oxidation state of catechol, among other features. We also summarized recent developments in designing advanced biomimetic materials including coacervate-forming adhesives, mechanically improved nano- and micro-composite adhesive hydrogels, as well as smart and self-healing materials. Finally, we review the applications of catechol-functionalized materials for the use as biomedical adhesives, therapeutic applications, and antifouling coatings. © 2016 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 9-33.

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

Background

Cyanoacrylate(CA)-based tissue adhesives, although not widely used, are a feasible option to fix a mesh during abdominal hernia repair, due to its fast action and great bond strength. Their main disadvantage, toxicity, can be mitigated by increasing the length of their alkyl chain. The objective was to assess the in vitro cytotoxicity and in vivo biocompatibility in hernia repair of CAs currently used in clinical practice (Glubran(n-butyl) and Ifabond(n-hexyl)) and a longer-chain CA (OCA(n-octyl)), that has never been used in the medical field.

Methods

Formaldehyde release and cytotoxicity of unpolymerized(UCAs) and polymerized CAs(PCAs) were evaluated by macroscopic visual assessment, flow cytometry and Alamar Blue assays. In the preclinical evaluation, partial defects were created in the rabbit abdominal wall and repaired by fixing polypropylene prostheses using the CAs. At 14 days post-surgery, animals were euthanized for morphology, macrophage response and cell damage analyses.

Results

Formaldehyde release was lower as the molecular weight of the monomer increased. The longest side-chain CA(OCA) showed the highest cytotoxicity in the UCA condition. However, after polymerization, was the one that showed better behavior on most occasions. In vivo, all CAs promoted optimal mesh fixation without displacements or detachments. Seroma was evident with the use of Glubran, (four of six animals: 4/6) and Ifabond (2/6), but it was reduced with the use of OCA (1/6). Significantly greater macrophage responses were observed in groups where Glubran and Ifabond were used vs. sutures and OCA. TUNEL-positive cells were significantly higher in the Glubran and OCA groups vs. the suture group.

Conclusions

Although mild formaldehyde release occurred, OCA was the most cytotoxic during polymerization but the least once cured. The CAs promoted proper mesh fixation and have potential to replace traditional suturing techniques in hernia repair; the CAs exhibited good tissue integration and effective short-term biocompatibility, with the slightest seroma and macrophage response induced by OCA.

Emerging Trends in Abdominal Wall Reinforcement: Bringing Bio-Functionality to Meshes

Abdominal wall hernia is a recurrent issue world-wide and requires the implantation of over 1 million meshes per year. Because permanent meshes such as polypropylene and polyester are not free of complications after implantation, many mesh modifications and new functionalities have been investigated over the last decade. Indeed, mesh optimization is the focus of intense development and the biomaterials utilized are now envisioned as being bioactive substrates that trigger various physiological processes in order to prevent complications and to promote tissue integration. In this context, it is of paramount interest to review the most relevant bio-functionalities being brought to new meshes and to open new avenues for the innovative development of the next generation of meshes with enhanced properties for functional abdominal wall hernia repair.

Injectable dopamine-modified poly(ethylene glycol) nanocomposite hydrogel with enhanced adhesive property and bioactivity

A synthetic mimic of mussel adhesive protein, dopamine-modified four-armed poly(ethylene glycol) (PEG-D4), was combined with a synthetic nanosilicate, Laponite (Na(0.7+)(Mg5.5Li0.3Si8)O20(OH)4)(0.7-)), to form an injectable naoncomposite tissue adhesive hydrogel. Incorporation of up to 2 wt % Laponite significantly reduced the cure time while enhancing the bulk mechanical and adhesive properties of the adhesive due to strong interfacial binding between dopamine and Laponite. The addition of Laponite did not alter the degradation rate and cytocompatibility of PEG-D4 adhesive. On the basis of subcutaneous implantation in rat, PEG-D4 nanocomposite hydrogels elicited minimal inflammatory response and exhibited an enhanced level of cellular infiltration as compared to Laponite-free samples. The addition of Laponite is potentially a simple and effective method for promoting bioactivity in a bioinert, synthetic PEG-based adhesive while simultaneously enhancing its mechanical and adhesive properties.

What do we know about titanized polypropylene meshes? An evidence-based review of the literature

PURPOSE

Despite the vast selection of brands available, nearly all synthetic meshes for hernia surgery continue to use one or other of three basic materials: polypropylene, polyester and ePTFE. These are used in combination with each other or with a range of additional materials such as titanium, omega 3, monocryl, PVDF and hyaluronate. This systematic review of all experimental and clinical studies is aimed at investigating whether titanized meshes confer advantages over other synthetic meshes in hernia surgery.

MATERIALS AND METHODS

A search of the medical literature from 2002 to 2012, as indexed by Medline, was performed, using the PubMed search engine (http://www.pubmed.gov). The search terms were: hernia mesh, titanium coating, lightweight mesh, TiMesh, mesh complications. All papers were graded according to the Oxford hierarchy of evidence.

RESULTS

Patients operated on with the Lichtenstein technique performed using the lightweight titanium-coated mesh have a shorter convalescence than those with the heavy-weight mesh Prolene. For inguinal hernias operated on with the TAPP technique and using a lightweight titanium-coated mesh in comparison to a heavy-weight Prolene mesh, the early postoperative convalescence seems to improve. Titanized meshes do exhibit a negative effect on sperm motility 1 year after a TEP operation, but not after 3 years. The laparoscopic IPOM technique with a titanium-coated polypropylene mesh was associated with less postoperative pain in the short term, lower analgesic consumption and a quicker return to everyday activities compared with the Parietex composite mesh.

CONCLUSION

In clinical studies, the titanium-coated polypropylene mesh shows in inguinal hernia repair certain benefits compared with the use of older heavy-weight meshes.

Novel biological strategies in the management of anal fistula

BACKGROUND

The mostly widely studied biomaterials for the sphincter sparing treatment of anal fistulas are fibrin glue and the anal fistula plug (AFP). However their overall mean clinical success is only 50-60%. As the understanding of the pathology of anal fistula, wound healing and the host response to materials has improved, so new biological sphincter-sparing strategies have been developed. The aim of this review is to assess the safety and efficacy of these novel techniques.

METHOD

PubMed, the Cochrane database and EMBASE were independently searched. All studies that investigated the potential of a biomaterial (defined as any synthetic or biologically derived substance in contact with host tissue) to augment the healing of anal fistula without sphincter division were included. Studies solely describing the role of fibrin glue or an AFP were excluded. Data extraction included type of material, fistula aetiology, treatment of the primary tract, fistula healing, incontinence, duration of follow-up and any specific complications. Systematic quality assessment of the included articles was performed.

RESULTS

Twenty-three articles were finally selected for review. These included a variety of biological and synthetic systems that were employed to deliver selected components of the extracellular matrix, growth factors, cytokines, stem cells or drugs to the fistula tract.

CONCLUSION

To date no study matches fistulotomy with regard to long-term fistula eradication rate. This is probably due to implant extrusion, inadequate track preparation or an unsuitable material. Future techniques need to address all these issues to ensure success. Success should be validated by MRI or long-term follow-up.

Biomechanical properties of (semi-) synthetic glues for mesh fixation in endoscopic inguinal hernia repair

PURPOSE

In endoscopic inguinal hernia repair, the use of fibrin glues for mesh fixation instead of staples and sutures can demonstrably reduce postoperative morbidity without increasing the recurrence rate. Various fibrin glues differ in terms of their mesh fixation strength. As an alternative to fibrin glue, there is an increasing trend toward using synthetic glues for mesh fixation in both open and endoscopic inguinal hernia surgery. To date, no studies have been conducted comparing the fixation strength of (semi-) synthetic glues with that of fibrin glues. Here, using a biomechanical model, we compared the adhesive strength of two glues (BioGlue and Glubran) used in surgery with a fibrin glue.

METHODS

We used light-weight polypropylene meshes (TiMesh light). In each case, the biomechanical stability of five meshes in each group was tested with 2 ml fibrin glue (Evicel), 2 ml BioGlue or 2 ml Glubran (cyanoacrylate). The defect in the muscle tissue used was 4.5 cm in diameter for a mesh size of 10 × 15 cm. Measurements were taken using a standardized stamp penetration test while aiming not to remain under a minimum fixation strength of 32 N.

RESULTS

Using Evicel for mesh fixation, an adhesive strength of 64.3 N was achieved. This was significantly greater than that obtained in the absence of fixation (2.9 N, p < 0.001) and higher than the requisite value of 32 N. Using Glubran, it was possible once again to significantly improve the adhesive strength (105.4 N, p = 0.008). The use of BioGlue improved the adhesive strength to 131.7 N, but not significantly so compared with Glubran (p = 0.110).

CONCLUSIONS

In terms of adhesive strength, (semi-) synthetic glues can be used for mesh fixation instead of fibrin glue and even achieve significantly better adhesive strength than fibrin glue. However, further clinical studies are needed to identify the role of (semi-) synthetic glues compared with fibrin glues in endoscopic inguinal hernia surgery.

The Glubran 2 glue for mesh fixation in Lichtenstein's hernia repair: a double-blind randomized study

Introduction

With an average incidence rate of 11%, chronic pain is considered the most serious complication of inguinal hernioplasty after surgical site infection. One of the proposed solutions to this problem is to use tissue adhesive for mesh fixation, which helps prevent nerve and tissue damage.

Aim

The goal of this study was to compare mesh fixation with the use of sutures vs. adhesive in Lichtenstein's inguinal hernia repair in a randomized, double-blind one-center study.

Material and methods

The study group consisted of 41 males with primary inguinal hernia undergoing Lichtenstein's repair (20 – adhesive; 21 – suture) and remaining in follow-up from July 2008 to November 2010. Randomization took place during the operation. The follow-up was performed by one surgeon (blinded) according to a pre-agreed schedule; the end-of-study unblinding was performed during the last follow-up visit, usually 16 months postoperatively.

Results

In 1 patient from the “adhesive” group, a recurrence was observed one year after the initial repair. The early postoperative pain was less intense in this group. In later postoperative periods the method of mesh fixation had no influence on the pain experienced by the patient. Other complications were not correlated with the method of mesh fixation.

Conclusions

In this randomized, one-center double-blind clinical study of males with primary inguinal hernia it has been show during follow-up that the use of Glubran 2 cyanoacrylate adhesive for mesh implant fixation yields similar recurrence and chronic pain rates as the classical suture technique. In the early postoperative period, the pain reported by these patients was relatively weaker; patients undergoing adhesive mesh fixation experienced a quicker return to daily household activities.

Efficiency and safety of mesh fixation in laparoscopic inguinal hernia repair using n-butyl cyanoacrylate: long-term biocompatibility in over 1,300 mesh fixations

Introduction

In adult patients, most inguinal hernias are treated by implanting a prosthetic mesh. To prevent mesh dislocation and thus recurrence, different types of fixation have been proposed. In contrast to penetrating fixation known to cause acute chronic pain, adhesive fixation is becoming increasingly popular as it reduces markedly the risk of injury and chronic pain. Apart from the biological sealants (e.g., fibrin glue), surgical adhesives include a group of synthetic glues and genetically engineered protein glues. For example, cyanoacrylate is used in various medical and veterinary indications due to its fast action, excellent bonding strength and low price.

Objective

The main objective of this paper was to communicate positive results obtained using n-butyl-cyanoacrylate glue to fix prosthetic meshes in over 1,300 TAPP repairs of primary and recurrent inguinal hernias. The secondary objective was to highlight the rationale (e.g., safety) for using non-fibrin based glue in this type of procedure.

Method

We present the in vitro and in vivo data necessary for the approval of n-butyl cyanoacrylate Histoacryl^® glue. We use an equivalent glue, Glubran-2^®, to fix prosthetic meshes in 1,336 laparoscopic TAPP repairs.

Results

Standardized tests to detect sensitization, irritation, genotoxicity or systemic toxicity demonstrated the safety and biocompatibility of Histoacryl^®, which met all requirements, including those of ISO 10993. Histological long-term studies in rabbits yielded results comparable to routine suture fixations, with full integration of the mesh into the abdominal wall. The clinical results showed the following advantages: fast application of the glue, reduced postoperative pain, 0.0% infection rate, continuously low recurrence rate and shorter hospital stay. No adverse effects and no complaints were recorded.

Conclusion

The experimental and clinical data demonstrate the safe use and the excellent cost-benefit ratio of n-butyl cyanoacrylate compared with other techniques of mesh fixation.

Randomized clinical trial of tissue glue versus absorbable sutures for mesh fixation in local anaesthetic Lichtenstein hernia repair

Background

Chronic pain may be a long-term problem related to mesh fixation and operative trauma after Lichtenstein hernioplasty. The aim of this study was to compare the feasibility and safety of tissue cyanoacrylate glue versus absorbable sutures for mesh fixation in Lichtenstein hernioplasty.

Methods

Lichtenstein hernioplasty was performed under local anaesthesia as a day-case operation in one of three hospitals. The patients were randomized to receive either absorbable polyglycolic acid 3/0 sutures (Dexon®; 151 hernias) or 1 ml butyl-2-cyanoacrylate tissue glue (Glubran®; 151 hernias) for fixation of lightweight mesh (Optilene®). Wound complications, pain, discomfort and recurrence were identified at 1 and 7 days, 1 month and 1 year after surgery.

Results

A total of 302 patients were included in the study. The mean(s.d.) duration of operation was 34(12) min in the glue group and 36(13) min in the suture group (P = 0·113). The need for analgesics was similar during the first 24 h after surgery. Five wound infections (3·4 per cent) were detected in the glue group and two (1·4 per cent) in the suture group (P = 0·448). The recurrence rate at 1 year was 1·4 per cent in each group (P = 1·000). The rates of foreign body sensation, acute and chronic pain were similar in the two groups. Logistic regression analysis showed that the type of mesh fixation did not predict chronic pain 1 year after surgery.

Conclusion

Mesh fixation without sutures in Lichtenstein hernioplasty was feasible without compromising postoperative outcome. Registration number: NCT00659542 (http://www.clinicaltrials.gov).

Novel technique of overlaying a poly-L: -lactic acid nanosheet for adhesion prophylaxis and fixation of intraperitoneal onlay polypropylene mesh in a rabbit model

BACKGROUND

One problem with polypropylene mesh (PPM) used to repair abdominal wall hernias is dense adhesions to the visceral surface. The authors developed the biocompatible poly-L: -lactic acid (PLLA) nanosheet (thickness < 100 nm), which has the unique ability to adhere tightly to tissues but not to opposing tissues. This study investigated the antiadhesive and fixative characteristics of the PLLA nanosheet after placement of intraperitoneal onlay PPM (IPOM) overlaid with a PLLA nanosheet on intact peritoneum.

METHODS

The PLLA nanosheet was fabricated by the spin-coating method and peeling technique with polyvinyl alcohol (PVA) as a supporting film. Two 1.5-cm-square pieces of mesh were implanted on each peritoneal side of the midline incision. The mesh was fixed to the peritoneum with a suture and then overlaid with a 4-cm-square piece of Seprafilm or nanosheet. To examine the fixative property, mesh was overlaid with Seprafilm or nanosheet without a fixed suture. After 4 weeks, mesh adhesion, inflammatory reaction, fixation, and dislocation of mesh were evaluated.

RESULTS

Nanosheet-overlaid meshes were flexible and fit over the peritoneum. Adhesion was observed in 10% of the nanosheet-overlaid meshes and in 50% of the Seprafilm-overlaid meshes. The adhesion tenacity grade was significantly lower with the nanosheet-overlaid meshes (0.1 ± 0.1) than with the Seprafilm-overlaid meshes (1.0 ± 0.4) (p = 0.029), and the percentage of the adhesion area also was lower with the nanosheet-overlaid meshes (1.0 ± 1.0% vs 8.5 ± 3.2%; p = 0.037). The mean inflammatory cell counts were lower with the nanosheet-overlaid meshes (p = 0.0023). Regarding the fixative property, 37.5% of the nanosheet-overlaid meshes were fixated on the peritoneum, but no Seprafilm-overlaid mesh was fixated.

CONCLUSION

Overlaying of a PLLA nanosheet was effective for adhesion prophylaxis of intraperitoneal mesh. It also may have a possible beneficial effect on fixation of mesh.

Biomechanical properties of Achilles tendon repair augmented with a bioadhesive-coated scaffold

The Achilles tendon is the most frequently ruptured tendon. Both acute and chronic (neglected) tendon ruptures can dramatically affect a patient's quality of life, and require a prolonged period of recovery before return to pre-injury activity levels. This paper describes the use of an adhesive-coated biologic scaffold to augment primary suture repair of transected Achilles tendons. The adhesive portion consisted of a synthetic mimic of mussel adhesive proteins that can adhere to various surfaces in a wet environment, including biologic tissues. When combined with biologic scaffolds such as bovine pericardium or porcine dermal tissues, these adhesive constructs demonstrated lap shear adhesive strengths significantly greater than that of fibrin glue, while reaching up to 60% of the strength of a cyanoacrylate-based adhesive. These adhesive constructs were wrapped around transected cadaveric porcine Achilles tendons repaired with a combination of parallel and three-loop suture patterns. Tensile mechanical testing of the augmented repairs exhibited significantly higher stiffness (22-34%), failure load (24-44%), and energy to failure (27-63%) when compared to control tendons with suture repair alone. Potential clinical implications of this novel adhesive biomaterial are discussed.

N-butyl cyanoacrylate versus conventional suturing for fixation of meshes in an incisional hernia model

BACKGROUND

Chronic pain and related complications reported after the use of perforating fixation devices in hernia surgery have led to the use of tissue sealants. Fibrin sealant is a feasible option for mesh fixation; however data on cyanoacrylate glues are limited.

METHODS

32 Sprague-Dawley rats were divided into two groups and a 1.5 cm abdominal wall defect was created on each animal. The lesions were then repaired with 2 × 2 cm polypropylene meshes, fixed with n-butyl-cyanoacrylate in the first group and with polypropylene sutures in the second group. The rats were sacrificed on the 21st and 42nd days. The presence of infection, recurrence, and abdominal adhesions were evaluated, followed by biomechanical testing and histological examination.

RESULTS

No mesh infection or hernia recurrences were recorded. There was no statistically significant difference between neither the adhesion scores nor the mean broken pressure of the two groups. Cyanoacrylate sealing was found equivalent to suturing in terms of tissue ingrowth, fibrosis, inflammatory infiltration, abscess formation, and necrosis. Furthermore, cyanoacrylate resulted in less foreign body reaction.

CONCLUSIONS

Mesh fixation by cyanoacrylate may be considered as an alternative to suture fixation.

Adhesive performance of biomimetic adhesive-coated biologic scaffolds

Surgical repair of a discontinuity in traumatized or degenerated soft tissues is traditionally accomplished using sutures. A current trend is to reinforce this primary repair with surgical grafts, meshes, or patches secured with perforating mechanical devices (i.e., sutures, staples, or tacks). These fixation methods frequently lead to chronic pain and mesh detachment. We developed a series of biodegradable adhesive polymers that are synthetic mimics of mussel adhesive proteins (MAPs), composed of 3,4-dihydroxyphenylalanine (DOPA)-derivatives, polyethylene glycol (PEG), and polycaprolactone (PCL). These polymers can be cast into films, and their mechanical properties, extent of swelling, and degradation rate can be tailored through the composition of the polymers as well as blending with additives. When coated onto a biologic mesh used for hernia repair, these adhesive constructs demonstrated adhesive strengths significantly higher than fibrin glue. With further development, a precoated bioadhesive mesh may represent a new surgical option for soft tissue repair.

Effectiveness and safety of CEUS-guided haemostatic injection for blunt splenic trauma: an animal experiment

The aim of this study was to investigate whether complications occur after haemostatic agents are injected into blunt splenic injuries. After undergoing ultrasound (US), contrast-enhanced US (CEUS) and contrast-enhanced computed tomography (CECT) examinations, dogs with grade III-IV injury received the minimally invasive therapy. After treatment, CEUS was performed to observe changes in the regions treated. In the immediate group, dogs underwent laparotomy 30 min after treatment to observe the haemostatic effect. In the survival group, animals underwent CEUS and CECT examinations to observe the short-term healing outcome and complications at 3, 7, 14, and 21 days after the injection. After undergoing CEUS and CECT examinations, 12 dogs with grade III-IV injury received the minimally invasive therapy. Before injection, CEUS examinations showed anechoic and/or hypoechoic perfusion defects and active bleeding at the injury sites, and CECT showed traumatic lesions as low-density regions without enhancement. After treatment, CEUS demonstrated the disappearance of active bleeding, and hyperechoic spots emerged at the injury sites. Uneven density regions were displayed on CECT. Treated areas were covered by blood clots and glue membrane in the immediate-group animals. Three weeks later, CEUS showed a decrease of hyperechoic spots in the survival group, and the splenic parenchyma enhanced uniformly on CECT. Laparotomy showed that the greater omentum had moved upwards and partly covered the wound in four animals, and the injury sites had completely healed. Histopathological examination showed that fibrous connective tissue covered the splenic capsule and that the haemostatic glue had degraded. No complication occurred, such as delayed splenic haemorrhage, splenic abscesses, splenic pseudoaneurysms, intestinal obstruction or intestinal adhesions. CEUS-guided haemostatic injection is not only effective in stopping active bleeding immediately, but it is also safe in that no complications occurred during the 3 weeks of follow-up. This study indicates that CEUS-guided percutaneous injection may provide a safe, feasible and effective therapy for blunt splenic trauma.

Cyanoacrylate surgical glue as an alternative to suture threads for mesh fixation in hernia repair

BACKGROUND

In recent years, the use of synthetic glues has become an established practice in several areas of surgical treatment. For example, they are used in open and laparoscopic surgery and in digestive tract endoscopy, interventional radiology, and vascular neuroradiology. The experiments in this study were aimed at elucidating that suture-based permanent mesh fixation can be replaced by fixation with N-butyl 2-cyanoacrylate glue (Glubran2) for surgical repair of abdominal wall hernias.

MATERIALS AND METHODS

In 25 Wistar rats, two hernia defects (1.5 cm in diameter) per animal were created bilaterally in the midline of the abdominal wall. The peritoneum was spared. The lesions were left untreated for 10 d to achieve a chronic condition. Then the defects were covered with TiMESH extralight (2 × 2 cm) and fixed by 30 μL of Glubran2 or traditional suture. The time points of sacrifice were 17 and 28 d, 3, 4, and 5 mo. At autopsy, histology and immunohistochemistry were performed to evaluate the inflammatory response and the presence of apoptotic cells respectively.

RESULTS

Mesh fixation was excellent in all samples at each time point. At application sites, the inflammatory reaction was mild with a small number of macrophages and vascularized connective tissue presence around glue and mesh threads. Glue residues were observed in histologic sections at each time point. No presence of apoptotic cells was found.

CONCLUSIONS

This study demonstrated that Glubran2 can effectively replace traditional suture in mesh fixation without affecting tissue healing and determining a physiological inflammatory reaction at the abdominal wall site.

A comparison of a bovine albumin/glutaraldehyde glue versus fibrin sealant for hernia mesh fixation in experimental onlay and IPOM repair in rats

BACKGROUND

Research in hernia repair has targeted new atraumatic mesh fixation to reduce major complications such as chronic pain and adhesion formation. The efficacy and safety of two surgical adhesives, viz. Artiss® (FS, fibrin sealant containing 4 IU thrombin) and Bioglue® (AGG, bovine serum albumin/glutaraldehyde glue), were evaluated in this study. Primary study endpoints were tissue integration, dislocation, and adhesion formation. Foreign-body reaction formed the secondary study endpoint.

METHODS

Twenty-four polypropylene meshes (VM, Vitamesh®) were randomized to four groups (n = 6): two groups of onlay hernia repair (two meshes per animal) with mesh fixation by FS (O-FS) or by AGG (O-AGG), and two groups of IPOM repair (one mesh per animal) with mesh fixation by four sutures and FS (I-FS) or AGG (I-AGG). Eighteen rats underwent surgery. Follow-up was 30 days. Tissue integration, dislocation, seroma formation, inflammation, adhesion formation, and foreign-body reaction were assessed.

RESULTS

Meshes fixed with FS (O-FS, I-FS) showed good tissue integration. No dislocation, seroma formation, or macroscopic signs of inflammation were detectable. Adhesion formation of I-FS was significantly milder compared with I-AGG (P = 0.024). A moderate foreign-body reaction without active inflammation was seen histologically in O-FS and I-FS groups. Samples fixed with AGG (O-AGG, I-AGG) showed extensive scar formation. No dislocation and no seroma formation were observed. All of these samples showed moderate to severe signs of inflammation with abscess formation in the six meshes of O-AGG. Histology underlined these findings.

CONCLUSIONS

The fibrin sealant adhesive showed very good overall results of the primary and secondary outcome parameters. FS is a recommendable atraumatic fixation tool for the surgical onlay technique. AGG provides high adhesive strength, but shows low biocompatibility. Persisting active inflammation was seen in both the O-AGG and I-AGG groups, not favoring its use for these indications.

Fibrin sealant (Tisseel) for hiatal mesh fixation in an experimental model in pigs

BACKGROUND

This study was designed to assess the efficacy of the fibrin sealant fixation of titanized polypropylene mesh in experimental hiatal mesh closure in pigs. Prosthetic hiatal closure is recommended for the repair of large hiatal/paraesophageal hernias as well as for antireflux surgery. However, only limited data exist on the favorable choice of meshes and fixation devices. Migration of the implant and trauma to neighboring organs due to perforating devices, such as sutures or tacks, present potentially lethal complications. In this study, we propose the fixation of titanized polypropylene meshes (TS) specifically developed for hiatal closure (TISure; GfE Medizintechnik GmbH, Nuremberg, Germany) with human fibrin sealant (FS, Tisseel; Baxter Biosciences, Vienna, Austria).

MATERIALS AND METHODS

A laparotomy was carried out in 7 mini-pigs (27-30 kg bodyweight) under general anaesthesia, and a TS was implanted after precise dissection of the right and left crura and the crural commissure. The key hole of the TS was placed around the esophagus at the gastroesophageal junction. One mL of FS was applied with the Easy Spray system (Baxter Biosciences, Vienna, Austria) for circular and three dimensional mesh fixation onto the diaphragm. Due to the lack of accepted gold standards of hiatal mesh reinforcement, no control group was used. Animals were sacrificed after 4 wk, and meshes were explanted after macroscopical assessment of the correct position and tissue integration. Histology was performed.

RESULTS

All meshes showed excellent tissue integration and no signs of migration or dislocation. FS was completely degraded and replaced by well vascularized fibroblastic tissue.

CONCLUSIONS

Titanized polypropylene mesh with FS fixation was found to be a safe and efficient combination for reinforcement of the hiatal closure in this preliminary experimental model.