Fabrication of silk mesh with enhanced cytocompatibility: preliminary in vitro investigation toward cell-based therapy for hernia repair

Modified polymeric biomaterials with antimicrobial and immunomodulating properties

The modification of the surgical polypropylene mesh and the polytetrafluoroethylene vascular prosthesis with cecropin A (small peptide) and puromycin (aminonucleoside) yielded very stable preparations of modified biomaterials. The main emphasis was placed on analyses of their antimicrobial activity and potential immunomodulatory and non-cytotoxic properties towards the CCD841 CoTr model cell line. Cecropin A did not significantly affect the viability or proliferation of the CCD 841 CoTr cells, regardless of its soluble or immobilized form. In contrast, puromycin did not induce a significant decrease in the cell viability or proliferation in the immobilized form but significantly decreased cell viability and proliferation when administered in the soluble form. The covalent immobilization of these two molecules on the surface of biomaterials resulted in stable preparations that were able to inhibit the multiplication of Staphylococcus aureus and S. epidermidis strains. It was also found that the preparations induced the production of cytokines involved in antibacterial protection mechanisms and stimulated the immune response. The key regulator of this activity may be related to TLR4, a receptor recognizing bacterial LPS. In the present study, these factors were produced not only in the conditions of LPS stimulation but also in the absence of LPS, which indicates that cecropin A- and puromycin-modified biomaterials may upregulate pathways leading to humoral antibacterial immune response.

Silk Meshes Coated with Chitosan-Bioactive Phytochemicals Activate Wound Healing Genes In Vitro

Meshes from natural silk are hand knitted and surface functionalized to facilitate hernia repair and other load bearing, tissue applications. Purified organic silk is - hand knitted and then coated with chitosan (CH)/bacterial cellulose (BC) blend polymer using four phytochemicals such as pomegranate (PG) peel, Nigella sativa (NS) seed, Licorice root (LE), and Bearberry leaf extracts (BE) separately. Characterizations using GCMS analysis shows the presence of bioactive chemicals in the extracts. Scanning electron microcopy (SEM) shows that the surface is coated with the composite polymer t. Fourier transform infrared spectroscopy (FTIR) shows significant elements found in CH, BC, and phytochemicals in plant extracts with no chemical changes. Tensile strength of the coated meshes is higher to support tissue as implants. The release kinetics suggest sustained release of phytochemical extracts. In vitro studies confirmed the noncytotoxic, biocompatible, wound healing potential of the meshes. Furthermore, gene expression analysis of 3-wound healing genes shows marked increase in the in vitro cell cultures due to the presence of extracts. These results suggest that the composite meshes can efficiently support hernia closure while facilitating wound/tissue healing and combating bacterial infections. Therefore, these meshes can be good candidates for fistula and cleft palate repair.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Comparative Evaluation of Two Hyaluronic Acid Gel Products for the Treatment of Interdental Papillary Defects

Objectives

The aim was to investigate the efficacy of single injections of two different hyaluronic acid products, Flex Barrier and Revident, in reducing the size of black triangles to treat Nordland-Tarnow Class I and II recessions.

Materials and Methods

Forty adult patients were recruited with at least two upper and two lower interdental papilla defects in the front region between canine teeth. According to the Nordland-Tarnow classification of papillary defects, both Class I and Class II recessions were included in the investigation. Patients were randomly assigned to experimental groups to receive single injections of two different hyaluronic acid products, either Flex Barrier or Revident. The untreated sites served as controls. Photographs were taken before and immediately after the treatment, and again after one week and one month. To determine the size of the black triangles, Image J software was used. For statistical analysis, a mixed-design ANOVA was applied.

Results

Both Flex Barrier and Revident significantly decreased the size of the treated defects immediately after the treatment and also one week later (p<0.001). The beneficial effect of Revident lasted longer than Flex Barrier as it remained significant even after one month in Revident-treated patients, however, not in the Flex Barrier-treated group. Furthermore, Nordland-Tarnow Class I lesions generally showed a greater improvement than Class II lesions.

Conclusion

In this proof-of-concept, randomized clinical trial we have demonstrated the clinical applicability of both Flex Barrier and Revident, although Revident gave longer-lasting improvements than Flex Barrier. Further trials are needed to optimize multiple-application protocols for treating gingival black triangles.

Meshes in a mess: Mesenchymal stem cell-based therapies for soft tissue reinforcement

Surgical meshes are frequently used for the treatment of abdominal hernias, pelvic organ prolapse, and stress urinary incontinence. Though these meshes are designed for tissue reinforcement, many complications have been reported. Both differentiated cell- and mesenchymal stem cell-based therapies have become attractive tools to improve their biocompatibility and tissue integration, minimizing adverse inflammatory reactions. However, current studies are highly heterogeneous, making it difficult to establish comparisons between cell types or cell coating methodologies. Moreover, only a few studies have been performed in clinically relevant animal models, leading to contradictory results. Finally, a thorough understanding of the biological mechanisms of mesenchymal stem cells in the context of foreign body reaction is lacking. This review aims to summarize in vitro and in vivo studies involving the use of differentiated and mesenchymal stem cells in combination with surgical meshes. According to preclinical and clinical studies and considering the therapeutic potential of mesenchymal stem cells, it is expected that these cells will become valuable tools in the treatment of pathologies requiring tissue reinforcement. STATEMENT OF SIGNIFICANCE: The implantation of surgical meshes is the standard procedure to reinforce tissue defects such as hernias. However, an adverse inflammatory response secondary to this implantation is frequently observed, leading to a strong discomfort and chronic pain in the patients. In many cases, an additional surgical intervention is needed to remove the mesh. Both differentiated cell- and stem cell-based therapies have become attractive tools to improve biocompatibility and tissue integration, minimizing adverse inflammatory reactions. However, current studies are incredibly heterogeneous and it is difficult to establish a comparison between cell types or cell coating methodologies. This review aims to summarize in vitro and in vivo studies where differentiated and stem cells have been combined with surgical meshes.

Covalent binding of placental derived proteins to silk fibroin improves schwann cell adhesion and proliferation

Schwann cells play a key role in peripheral nerve regeneration. Failure in sufficient formation of Büngner bands due to impaired Schwann cell proliferation has significant effects on the functional outcome after regeneration. Therefore, the growth substrate for Schwann cells should be considered with highest priority in any peripheral nerve tissue engineering approach. Due to its excellent biocompatibility silk fibroin has most recently attracted considerable interest as a biomaterial for use as conduit material in peripheral nerve regeneration. In this study we established a protocol to covalently bind collagen and laminin, which have been isolated from human placenta, to silk fibroin utilizing carbodiimide chemistry. Altered adhesion, viability and proliferation of Schwann cells were evaluated. A cell adhesion assay revealed that the functionalization with both, laminin or collagen, significantly improved Schwann cell adhesion to silk fibroin. Moreover laminin drastically accelerated adhesion. Schwann cell proliferation and viability assessed with BrdU and MTT assay, respectively, were significantly increased in the laminin-functionalized groups. The results suggest beneficial effects of laminin on both, cell adhesion as well as proliferative behaviour of Schwann cells. To conclude, the covalent tailoring of silk fibroin drastically enhances its properties as a cell substratum for Schwann cells, which might help to overcome current hurdles bridging long distance gaps in peripheral nerve injuries with the use of silk-based nerve guidance conduits.

Biocompatibility of Subcutaneously Implanted Plant-Derived Cellulose Biomaterials

There is intense interest in developing novel biomaterials which support the invasion and proliferation of living cells for potential applications in tissue engineering and regenerative medicine. Decellularization of existing tissues have formed the basis of one major approach to producing 3D scaffolds for such purposes. In this study, we utilize the native hypanthium tissue of apples and a simple preparation methodology to create implantable cellulose scaffolds. To examine biocompatibility, scaffolds were subcutaneously implanted in wild-type, immunocompetent mice (males and females; 6-9 weeks old). Following the implantation, the scaffolds were resected at 1, 4 and 8 weeks and processed for histological analysis (H&E, Masson's Trichrome, anti-CD31 and anti-CD45 antibodies). Histological analysis revealed a characteristic foreign body response to the scaffold 1 week post-implantation. However, the immune response was observed to gradually disappear by 8 weeks post-implantation. By 8 weeks, there was no immune response in the surrounding dermis tissue and active fibroblast migration within the cellulose scaffold was observed. This was concomitant with the deposition of a new collagen extracellular matrix. Furthermore, active blood vessel formation within the scaffold was observed throughout the period of study indicating the pro-angiogenic properties of the native scaffolds. Finally, while the scaffolds retain much of their original shape they do undergo a slow deformation over the 8-week length of the study. Taken together, our results demonstrate that native cellulose scaffolds are biocompatible and exhibit promising potential as a surgical biomaterial.