Dopamine-Mediated Zwitterionic Polyelectrolyte-Coated Polypropylene Hernia Mesh with Synergistic Anti-inflammation Effects

Durable and Robust Antibacterial Polypropylene Hernia Mesh for Abdominal Wall Defect Repair

Polypropylene (PP) mesh is commonly used in repairing abdominal wall hernia (AWH). However, the use of synthetic prosthesis comes with the risk of developing a prosthetic infection, resulting in delayed healing, secondary surgery, and potentially increased mortality. To address these issues, a facile surface functionalization strategy for PP mesh based on phytic acid (PA) and polyhexamethylene guanidine (PHMG) was constructed through a one-step co-deposition process, referred to as the PA/PHMG coating. The development of PA/PHMG coating is mainly attributed to the surface affinity of PA and the electrostatic interactions between PA and PHMG. The PA/PHMG coating could be completed within 4 h under mild conditions. The prepared PA/PHMG coatings on PP mesh surfaces exhibited desirable biocompatibility toward mammalian cells and excellent antibacterial properties against the notorious "superbug" methicillin-resistant Staphylococcus aureus (MRSA) and tetracycline-resistant Escherichia coli (TRE). The PA/PHMG-coated PP meshes showed killing ratios of over 99% against MRSA in an infected abdominal wall hernia repair model. Furthermore, histological and immunohistochemical analysis revealed a significantly attenuated degree of neutrophil infiltration in the PA/PHMG coating group, attributed to the decreased bacterial numbers alleviating the inflammatory response at the implant sites. Meanwhile, the pristine PP and PA/PHMG-coated meshes showed effective tissue repair, with the PA/PHMG coating group exhibiting enhanced angiogenesis compared with pristine PP meshes, suggesting superior tissue restoration. Additionally, PP meshes with the highest PHMG weight ratio (PA/PHMG(3)) exhibited excellent long-term robustness under phosphate-buffered saline (PBS) immersion with a killing ratio against MRSA still exceeding 95% after 60 days of PBS immersion. The present work provides a facile and promising approach for developing antibacterial implants.

pH-Responsive antibacterial metal-phenolic network coating on hernia meshes

Polypropylene (PP) mesh is widely used in hernioplasty, but it is prone to contamination by pathogenic bacteria. Here, we present an infection microenvironment-responsive metal-phenolic network (MPN) coating, which is made up of Cu2+ and tannic acid (TA) (referred to as CT coating), and is fabricated on PP meshes by layer-by-layer (LbL) assembly. The CT coating provided a robust protection for the PP mesh from pathogenic bacterial infection in a pH-responsive manner due to the pH-responsive disassembly kinetics of MPN complexes. Moreover, the PP meshes with ten CT coating cycles (PP-CT(10)) exhibited excellent stability in a physiological environment, with the killing ratio against "superbug" methicillin-resistant Staphylococcus aureus (MRSA) at pH 5.5 exceeding 99% even after 28 days of PBS (pH 7.4) immersion. In addition, the PP-CT(10) exhibited excellent in vivo anti-infective ability in a rodent subcutaneous implant MRSA infection model, and the results of histological and immunohistochemical analyses demonstrated that the reduced bacterial number alleviated the inflammatory response at implant sites. This study revealed that MPN coating is a promising strategy, which could provide a self-defensive ability for various implants to combat post-surgical infections in a pH-responsive manner.

Temperature-responsive salt-resistant poly(sulfobetaine methacrylate)-based emulsifiers for heavy oils

The emulsions prepared with most currently reported emulsifiers are stable only at room temperature and are susceptible to demulsification at higher temperatures. This thermal instability prevents their use in high-temperature and high-salt environments encountered oilfield extraction. To address this issue, in this study, two temperature-responsive emulsifiers, PSBMA and CS-PSBMA, were synthesized. Both emulsifiers exhibited the ability to form stable emulsions within the temperature range of 60-80 °C and undergo demulsification at 20-40 °C. A comprehensive investigation was conducted to assess the impact of emulsifier concentration, water-to-oil ratio, and salt ion concentration on the stability of emulsions formed by these two emulsifiers. The results demonstrated their remarkable emulsification capabilities across diverse oil phases. Notably, the novel emulsifier CS-PSBMA, synthesized through the grafting chitosan (CS) onto PSBMA, not only exhibits superior emulsion stability and UCST temperature responsiveness but also significantly enhanced the salt resistance of the emulsion. Remarkably, the emulsion maintained its stability even in the presence of monovalent salt ions at concentrations up to 2 mol/L (equivalent to a mineralization level of 1.33 × 105 mg/L in water) and divalent salt ions at concentrations up to 3 mol/L (equivalent to a mineralization level of 2.7 × 105 mg/L in water). The emulsions stabilized by both emulsifiers are resilient to harsh reservoir conditions and effectively emulsify heavy oils, enabling high-temperature emulsification and low-temperature demulsification. These attributes indicate their promising potential for industrial applications, particularly in the field of enhanced oil recovery.

Zwitterion mediated anti-protein adsorption on polypropylene mesh to reduce inflammation for efficient hernia repair

The effectiveness of polypropylene (PP) mesh is often compromised by severe inflammation. Engineering anti-inflammatory coatings has significant implications for PP mesh to repair unwanted hernias. Here, we presented a facile strategy to develop an anti-fouling coating consisting of zwitterionic poly(carboxybetaine methacrylate) (PCBMA), which could prohibit protein adsorption to endow PP mesh with anti-inflammatory efficacy. The incorporation of PCBMA coating had little impact on the raw features of PP mesh. While the modified mesh PCBMA-PP possessed noticeable hydrophilicity increase and surface charge reduction. The excellent lubricity and surface stability enabled PCBMA-PP to exhibit superior anti-fouling capacity, thus efficiently inhibiting the adsorption of proteins. In vivo experiments showed that incorporating the PCBMA layer could provide PP meshes with outstanding anti-inflammatory effects and tissue compatibility for repairing hernias.

A Review of Advanced Abdominal Wall Hernia Patch Materials

Tension-free abdominal wall hernia patch materials (AWHPMs) play an important role in the repair of abdominal wall defects (AWDs), which have a recurrence rate of <1%. Nevertheless, there are still significant challenges in the development of tailored, biomimetic, and extracellular matrix (ECM)-like AWHPMs that satisfy the clinical demands of abdominal wall repair (AWR) while effectively handling post-operative complications associated with abdominal hernias, such as intra-abdominal visceral adhesion and abnormal healing. This extensive review presents a comprehensive guide to the high-end fabrication and the precise selection of these advanced AWHPMs. The review begins by briefly introducing the structures, sources, and properties of AWHPMs, and critically evaluates the advantages and disadvantages of different types of AWHPMs for AWR applications. The review subsequently summarizes and elaborates upon state-of-the-art AWHPM fabrication methods and their key characteristics (e.g., mechanical, physicochemical, and biological properties in vitro/vivo). This review uses compelling examples to demonstrate that advanced AWHPMs with multiple functionalities (e.g., anti-deformation, anti-inflammation, anti-adhesion, pro-healing properties, etc.) can meet the fundamental clinical demands required to successfully repair AWDs. In particular, there have been several developments in the enhancement of biomimetic AWHPMs with multiple properties, and additional breakthroughs are expected in the near future.

Surface Modification of Nanopores in an Anodic Aluminum Oxide Membrane through Dopamine-Assisted Codeposition with a Zwitterionic Polymer

Surface modification through dopamine-assisted codeposition with functional zwitterionic polymers can provide a simple and one-step functionalization under ambient conditions with robust and stable dopamine-surface interactions to improve the hydrophilicity of nanoporous membranes, thereby expanding their applicability to nanofiltration, ion transport, and blood purification. However, a significant knowledge gap remains in our comprehension of the mechanisms underlying the formation and deposition of dopamine/polymer aggregated coatings within nanoscale confinement. This study explores a feasible method for membrane modification through the codeposition of dopamine hydrochloride (DA) and poly(sulfobetaine methacrylate) (PSBMA) on nanopores of anodic aluminum oxide (AAO) membranes. Our findings demonstrate that the aggregated coatings of DA and PSBMA nanocomposites can effectively deposit on the surfaces within cylindrical AAO nanopores, significantly enhancing the hydrophilicity of the nanoporous membranes. The morphology and homogeneity of the nanocomposite coatings within the nanopores are further investigated by varying PSBMA molecular weights and AAO pore sizes, revealing that higher molecular weights result in more uniform deposition. This work sheds light on understanding the codeposition of DA and zwitterionic polymers in nanoscale environments, highlighting a straightforward and stable surface modification process of nanoporous membranes involving functional polymers.

Inflammation in Hernia and the epigenetic control

Inflammation is much more intrinsic to hernia then is what is generally appreciated. The occurrence of hernias is associated with swelling, stress and inflammation. Surgery remains an important intervention to treat hernias and for many years, post-surgical levels of inflammatory cytokines have been evaluated to compare the different strategies for their comparative advantages. All surgical procedures elicit some sort of inflammatory response and moreover the meshes used for hernia repair are also associated with elevated inflammatory response, although some favor predominantly a pro-inflammatory response while the other meshes favor anti-inflammatory response. An estimated more than 90% of hernia repairs involve some meshes with polypropylene considered as the gold standard. Efforts are underway to modulate polypropylene meshes associated inflammation through use of alternative materials as well as modifications to polypropylene meshes themselves. In the last one decade, miRNAs have entered hernia research and the data on a role of miRNAs in different hernias is slowly emerging, providing the first evidence of epigenetics in hernia. Some reports are connecting miRNAs with inflammation in hernia. All these aspects, such as, surgery-related to mesh-related inflammation as well as miRNA-related inflammation, are discussed in this article to present an up-to-date information on the topic.

Polypropylene composite mesh modified by polyurethane gel with ROS scavenging and anti-inflammatory effects for pelvic floor repair

Development of an inflammation modulating polypropylene (PP) mesh in pelvic floor repair is an urgent clinical need. This is because PP mesh for pelvic floor repair can cause a series of complications related to foreign body reactions (FBR) in postoperative period. Therefore, we successfully prepared PP composite mesh that can scavenge reactive oxygen species (ROS) and inhibit inflammation to moderate FBR by a simple method. First, a pregel layer was formed on PP mesh by dip coating. Among them, polyurethane with polythioketal (PTK) is an excellent ROS scavenger, and dopamine methacrylamide (DMA) improves the stability of the coating and synergistically scavenges ROS. Then, a composite mesh (optimal PU50-PP) was obtained by photopolymerization. The results showed that the polyurethane gel layer was able to scavenge more than 90% of free radicals and about 75% of intracellular ROS. In vitro, PU50-PP mesh significantly scavenged ROS and resisted macrophage adhesion. After implantation in the posterior vaginal wall of rats, PU50-PP eliminated 53% of ROS, inhibited inflammation (decreased IL-6, increased IL-10), and dramatically reduced collagen deposition by about 64%, compared to PP mesh. Thus, the composite PP mesh with ROS scavenging and anti-inflammatory properties provides a promising approach for mitigating FBR.

Novel Material Optimization Strategies for Developing Upgraded Abdominal Meshes

Over 20 million hernias are operated on globally per year, with most interventions requiring mesh reinforcement. A wide range of such medical devices are currently available on the market, most fabricated from synthetic polymers. Yet, searching for an ideal mesh is an ongoing process, with continuous efforts directed toward developing upgraded implants by modifying existing products or creating innovative systems from scratch. In this regard, this review presents the most frequently employed polymers for mesh fabrication, outlining the market available products and their relevant characteristics, further focusing on the state-of-the-art mesh approaches. Specifically, we mainly discuss recent studies concerning coating application, nanomaterials addition, stem cell seeding, and 3D printing of custom mesh designs.

Abdominal wall hernia repair: from prosthetic meshes to smart materials

Hernia reconstruction is one of the most frequently practiced surgical procedures worldwide. Plastic surgery plays a pivotal role in reestablishing desired abdominal wall structure and function without the drawbacks traditionally associated with general surgery as excessive tension, postoperative pain, poor repair outcomes, and frequent recurrence. Surgical meshes have been the preferential choice for abdominal wall hernia repair to achieve the physical integrity and equivalent components of musculofascial layers. Despite the relevant progress in recent years, there are still unsolved challenges in surgical mesh design and complication settlement. This review provides a systemic summary of the hernia surgical mesh development deeply related to abdominal wall hernia pathology and classification. Commercial meshes, the first-generation prosthetic materials, and the most commonly used repair materials in the clinic are described in detail, addressing constrain side effects and rational strategies to establish characteristics of ideal hernia repair meshes. The engineered prosthetics are defined as a transit to the biomimetic smart hernia repair scaffolds with specific advantages and disadvantages, including hydrogel scaffolds, electrospinning membranes, and three-dimensional patches. Lastly, this review critically outlines the future research direction for successful hernia repair solutions by combing state-of-the-art techniques and materials.

Carboxymethyl chitosan/sodium alginate hydrogels with polydopamine coatings as promising dressings for eliminating biofilm and multidrug-resistant bacteria induced wound healing

Microorganisms induced wound infection and the accompanying excessive inflammatory response is the daunting problems in wound treatment. Due to the lack of corresponding biological functions, traditional wound dressings cannot effectively protect the wound and are prone to induce local infection, excessive inflammation, and vascular damage, resulting in prolonged unhealing. Here, a mussel-inspired strategy was adopted to prepare a multifunctional hydrogel created by H₂O₂/CuSO₄-induced rapid polydopamine (PDA) deposition on carboxymethyl chitosan (CMC)/sodium alginate (Alg) based hydrogel, termed as CAC/PDA/Cu(H₂O₂). The prepared CAC/PDA/Cu(H₂O₂) hydrogel features excellent biocompatibility, adequate mechanical properties, and good degradability. Moreover, the CAC/PDA/Cu(H₂O₂) hydrogel can not only realize antibacterial, and anti-inflammatory effects, but also promote angiogenesis to accelerate wound healing in vitro thanks to the composite PDA/Cu(H₂O₂) coatings. Significantly, CAC/PDA/Cu(H₂O₂) hydrogel illustrates excellent therapeutic effects in Methicillin-resistant Staphylococcus aureus (MRSA) induced-rat infection models, which can efficiently eliminate MRSA, dramatically reduce inflammatory expression, promote angiogenesis, and ultimately shorten the wound healing time. CAC/PDA/Cu(H₂O₂) hydrogel exhibited the best wound healing rate on days 7 (80.63 ± 2.44 %), 11 (92.45 ± 2.26 %), and 14 (97.86 ± 0.66 %). Thus, the multifunctional hydrogel provides a facile and efficient approach to wound management and represents promising potential in the therapy for wound healing.

Hydrophilic Polymer-Guided Polycatecholamine Assembly and Surface Deposition

Mussel-inspired surface chemistry based on polycatecholamines and polyphenols has been widely applied as a facile and universal method for modifying surfaces. Specifically, the catecholamine-assisted codeposition as a one-step strategy is a versatile strategy used to impart surface functionalities. Despite successful incorporation of numerous functional agents, very little understanding has emerged over the years regarding the mechanism behind their coassembly and codeposition. Here, we employed six different ultrahigh molecular weight hydrophilic polymers of diverse chemistry and architecture and three catecholamines and a polyphenol for investigating the coassembly and codeposition process. The chemistry of the polymers is found to influence the strength of the interaction between the polycatecholamine and the hydrophilic polymers, thus playing an important role in the aqueous self-assembly in solution to nanoaggregates, its formation kinetics, steric stabilization, and surface deposition. Additionally, the codeposition method was used as a platform for developing antifouling and antibiofilm coatings and evaluating their efficiency. Both the chemistry of hydrophilic polymers and the type of the catecholamine influence the antibiofilm properties of the coating. Our studies demonstrated that significant opportunities exist to further define the surface coating process and polycatecholamine self-assembly process by altering the polycatecholamine-hydrophilic polymer interactions.

Coordination-Driven Surface Zwitteration for Antibacterial and Antifog Applications

The enhancement of surface wettability by hydrophilic polymer coatings has been of great interest because it has been used to address several technical challenges such as biofouling and surface fogging. Among the hydrophilic polymers, zwitterionic polymers have been extensively utilized to coat solid surfaces due to their excellent capability to bind water molecules, thereby forming dense hydration layers on the solid surfaces. For these zwitterionic polymers to function appropriately on the solid surfaces, techniques for fixing polymers onto the solid surface with high efficiency are required. Herein, we report a new approach to graft zwitterionic polymers onto solid substrates. The approach is based on the mussel-inspired surface chemistry and metal coordination. It consists of polydopamine coating and the coordination-driven grafting of the zwitterionic polymers. Polydopamine coating enables the versatile surface immobilization of catechols. Zwitterionic polymers are then easily fixed onto the catechol-immobilized surface by metal-mediated crosslinking reactions. Using this approach, nanometer-thick zwitterionic polymer layers that are highly resistant to bacterial adhesion and fog generation could be successfully fabricated on solid substrates in a substrate-independent manner.

Latest Trends on the Attenuation of Systemic Foreign Body Response and Infectious Complications of Synthetic Hernia Meshes

Throughout the past few years, hernia incidence has remained at a high level worldwide, with more than 20 million people requiring hernia surgery each year. Synthetic hernia meshes play an important role, providing a microenvironment that attracts and harbors host cells and acting as a permanent roadmap for intact abdominal wall reconstruction. Nevertheless, it is still inevitable to cause not-so-trivial complications, especially chronic pain and adhesion. In long-term studies, it was found that the complications are mainly caused by excessive fibrosis from the foreign body reaction (FBR) and infection resulting from bacterial colonization. For a thorough understanding of their complex mechanism and providing a richer background for mesh development, herein, we discuss different clinical mesh products and explore the interactions between their structure and complications. We further explored progress in reducing mesh complications to provide varied strategies that are informative and instructive for mesh modification in different research directions. We hope that this work will spur hernia mesh designers to step up their efforts to develop more practical and accessible meshes by improving the physical structure and chemical properties of meshes to combat the increasing risk of adhesions, infections, and inflammatory reactions. We conclude that further work is needed to solve this pressing problem, especially in the analysis and functionalization of mesh materials, provided of course that the initial performance of the mesh is guaranteed.

A Fibrin Coating Method of Polypropylene Meshes Enables the Adhesion of Menstrual Blood-Derived Mesenchymal Stromal Cells: A New Delivery Strategy for Stem Cell-Based Therapies

Polypropylene (PP) mesh is well-known as a gold standard of all prosthetic materials of choice for the reinforcement of soft tissues in case of hernia, organ prolapse, and urinary incontinence. The adverse effects that follow surgical mesh implantation remain an unmet medical challenge. Herein, it is outlined a new approach to allow viability and adhesion of human menstrual blood-derived mesenchymal stromal cells (MenSCs) on PP surgical meshes. A multilayered fibrin coating, based on fibrinogen and thrombin from a commercial fibrin sealant, was optimized to guarantee a homogeneous and stratified film on PP mesh. MenSCs were seeded on the optimized fibrin-coated meshes and their adhesion, viability, phenotype, gene expression, and immunomodulatory capacity were fully evaluated. This coating guaranteed MenSC viability, adhesion and did not trigger any change in their stemness and inflammatory profile. Additionally, MenSCs seeded on fibrin-coated meshes significantly decreased CD4+ and CD8+ T cell proliferation, compared to in vitro stimulated lymphocytes (p < 0.0001). Hence, the proposed fibrin coating for PP surgical meshes may allow the local administration of stromal cells and the reduction of the exacerbated inflammatory response following mesh implantation surgery. Reproducible and easy to adapt to other cell types, this method undoubtedly requires a multidisciplinary and translational approach to be improved for future clinical uses.

Synergistic Anti-inflammatory Coating "Zipped Up" on Polypropylene Hernia Mesh

Violent inflammation has impeded worry-free application of polypropylene (PP) hernia meshes. Efficient anti-inflammatory coatings are urgently needed to alter the situation. Here, we present a zipper-like, two-layer coating with an intermediate antioxidant layer (I) and an outer antifouling layer (II) to endow PP meshes with synergistic anti-inflammatory effects. The controllable antioxidant ability of layer I was obtained by modulating the assembly cycle of the metal-phenolic network (MPN) composed of tannic acid (TA) and Fe3+. Polyzwitterionic (PMAD) brush-based layer II was generated upon multiple interactions between the catechol side groups of PMAD and layer I. To consolidate the entire assembly architecture, aryloxy radical coupling was initiated through alkali-catalyzed oxidation. The reaction is similar to a "zipping up" process to construct covalent bonds in the I-II interface and layer I by coupling adjacent catechol groups, which facilely achieved grafting and cross-linking. The obtained coating (PMAD-TA/Fe) did not affect the original properties of the PP mesh and remained stable during cyclic tensile testing or degradation. Most importantly, the excellent antioxidant and antifouling capacities enabled PMAD-TA/Fe-PP to exhibit desirable anti-inflammatory effects and reduce collagen deposition when compared with the bare material. The synergistic anti-inflammatory coating eliminates a major hindrance in the design of biocompatible meshes, and its potential application in developing medical implants with low immunogenicity is promising.

Filament-anchored hydrogel layer on polypropylene hernia mesh with robust anti-inflammatory effects

The efficacy of implanted polypropylene (PP) hernia meshes is often compromised by an inflammatory response. Thus, engineering an anti-inflammatory mesh has significant implications for hernioplasty. Here, we report a facile strategy to develop a filament-anchored hydrogel layer (FAHL) on PP mesh (FAHL-P). The network of FAHL, made up of chondroitin sulfate and gelatin (CG), provided a biomimetic surface with immunoregulatory properties. The use of tannic acid (TA) as a crosslinker for CG additionally enhanced its anti-inflammatory properties. In addition, the fabrication protocol ensured that the hydrogel maintained the properties of the knitted mesh and the firmly adherent FAHL during general handling (dry state) and in the simulated body environment (wet state). CG/TA-PP killed 99.99% of S. aureus and retained 73% of its original antioxidant properties after 7 d. The FAHL durably performed with a controlled release of TA for 15 d. The strong anti-inflammatory effects of FAHL-P reduced collagen deposition and increased vascularization, which promoted native tissue generation. The fabrication strategy has potential applications in hernioplasty and may provide new insights into the design of other anti-inflammatory implants. STATEMENT OF SIGNIFICANCE: A hydrogel layer with robust anti-inflammatory effects was anchored firmly on mesh filament for hernia repair. Requiring no drug loading, this chondroitin sulphate -gelatin (CG) based hydrogel itself could inhibit the immunological attack owing to the biomimetic microenvironment created by the CG. Moreover, the hydrogel's crosslinker (tannic acid) content served as an effective scavenger for reducing pro-inflammatory factors, significantly mitigating the inflammation. Interestingly, the antibacterial effect of such hydrogel layer was also observed. In terms of the synergistic outcome of the design, our mesh can remarkably attenuate inflammation and promote constructive tissue regeneration in vivo. Furthermore, considering the relatively simple and easily scaled up formulation process, our strategy may indeed have great potential in alleviating post-implantation outcomes.

Chitosan/gelatin-tannic acid decorated porous tape suture with multifunctionality for tendon healing

The inferior tendon healing after surgery is inextricably linked to the surgical suture. Poor load transfer along the suture often results in a high tendon re-tear rate. Besides, the severe inflammation and infection induced by sutures even cause a second surgery. Herein, to alleviate the above-mentioned issues, a multifunctional suture was fabricated by decorating chitosan/gelatin-tannic acid (CS/GE-TA) on the porous tape suture. The porous tape suture ensured the required mechanical properties and sufficient space for tissue integration. Compared to the pristine suture, the CS/GE-TA decorated suture (TA100) presented a 332% increase in pull-out force from the tendon, indicating potentially decreased re-tear rates. Meanwhile, TA100 showed superior anti-inflammatory and antibacterial performances. In vivo experiments further proved that TA100 could not only reduce inflammatory action but also facilitate collagen deposition and blood vessel formation. These results indicate that the multifunctional sutures are promising candidates for accelerating tendon healing.