Fibroin and sericin from Bombyx mori silk stimulate cell migration through upregulation and phosphorylation of c-Jun

Advances in arthropod-inspired bionic materials for wound healing

Arthropods contain lots of valuable bionic information from the composition to the special structure of the body. In particular, the rapid self-healing ability and antibacterial properties are amazing. Biomimetic materials for arthropods have been helpful methods for wound management. Here, we have identified four major dimensions needed to create biomimetic materials for arthropods, including ingredient, behavior, structure and internal reaction. According to different dimensions, we classify and introduce the reported arthropod biomimetic materials. Antibacterial, hemostatic and healing promotion are the main functions of the active compositions of arthropods developed by humans, and most of them play a drug effect. We believe that an ideal biomimetic material of arthropod should have the effect on promoting wound healing through the advantages of structure and composition. The special macroscopic and microscopic structure of the epidermis may provide good mechanical support for biomimetic materials. The drug release regularity in the bionic materials can be referred to the aggressive and secretory behavior of arthropods. The synthesis of substances in arthropods is also noteworthy, and we can learn these special reactions to complete the fast preparation of materials. Arthropod-inspired bionic materials have broad innovation and application prospects in the field of wound repair.

Vancomycin-Loaded Silk Fibroin/Calcium Phosphate/Methylcellulose-Based In Situ Thermosensitive Hydrogel: A Potential Function for Bone Regeneration

This study explores the efficacy of a vancomycin-loaded silk fibroin/calcium phosphate/methylcellulose-based in situ thermosensitive hydrogel (VM-SF/CaP/MC) in promoting the osteogenic differentiation of preosteoblast cells. Three VM-SF/CaP/MC formulations with varying low (L) and high (H) concentrations of silk fibroin (SF) and calcium phosphate (CaP) were prepared: VM-HSF/LCaP/MC, VM-LSF/HCaP/MC, and VM-HSF/HCaP/MC. These hydrogels significantly enhanced MC3T3-E1 cell migration and proliferation in a dose- and time-dependent manner, achieving complete cell migration within 48 h. In addition, they significantly promoted alkaline phosphatase activity, collagen content, and mineralization in MC3T3-E1 cells, indicating their potential for osteogenesis. Among the hydrogel formulations, the VM-HSF/HCaP/MC hydrogel, with high SF and CaP content, demonstrated superior potential in promoting the osteogenic differentiation of MC3T3-E1 cells. It exhibited the highest ALP activity (11.13 ± 0.91 U/mg protein) over 14 days, along with increased collagen content (54.00 ± 1.71 µg/mg protein) and mineralization (15.79 ± 1.48 mM) over 35 days. Therefore, this formulation showed a promising candidate for clinical application in localized bone regeneration, particularly in treating osteomyelitis.

Bioactive silk fibroin hydrogels: Unraveling the potential for biomedical engineering

Silk fibroin (SF) has received special attention from the scientific community due to its noteworthy properties. Its unique chemical structure results in an uncommon combination of macroscopically useful properties, yielding a strong, fine and flexible material which, in addition, presents good biodegradability and better biocompatibility. Therefore, silk fibroin in various formats, appears as an ideal candidate for supporting biomedical applications. In this review, we will focus on the hydrogels obtained from silk fibroin or in combination with it, paying special attention to the synthesis procedures, characterization methodologies and biomedical applications. Tissue engineering and drug-delivery systems are, undoubtedly, the two main areas where silk fibroin hydrogels find their place.

Application of Pro-angiogenic Biomaterials in Myocardial Infarction

Biomaterials have potential applications in the treatment of myocardial infarction (MI). These biomaterials have the ability to mechanically support the ventricular wall and to modulate the inflammatory, metabolic, and local electrophysiological microenvironment. In addition, they can play an equally important role in promoting angiogenesis, which is the primary prerequisite for the treatment of MI. A variety of biomaterials are known to exert pro-angiogenic effects, but the pro-angiogenic mechanisms and functions of different biomaterials are complex and diverse, and have not yet been systematically described. This review will focus on the pro-angiogenesis of biomaterials and systematically describe the mechanisms and functions of different biomaterials in promoting angiogenesis in MI.

Advancements in silk fibroin and silk sericin-based biomaterial applications for cancer therapy and wound dressing formulation: A comprehensive review

Silks are a class of proteins generated naturally by different arthropods, including silkworms, spiders, scorpions, mites, wasps, and bees. This review discusses the silk fibroin and silk sericin fabricated by Bombyx mori silkworm as versatile fibers. This silk fiber is predominantly composed of hydrophobic silk fibroin and hydrophilic silk sericin. Fibroin is defined as a structural protein that bestows silk with strength, while sericin is characterized as a gum-like protein, tying the two fibrous proteins together and endowing silk proteins with elasticity. Due to their versatile structures, biocompatibility, and biodegradability, they could be tailored into intricate structures to warrant particular demands. The intrinsic functional groups of both proteins enable their functionalization and cross-linking with various biomaterials to endow the matrix with favorable antioxidant and antibacterial properties. Depending on the target applications, they can be integrated with other materials to formulate nanofibrous, hydrogels, films, and micro-nanoparticles. Given the outstanding biological and controllable physicochemical features of fibroin and sericin, they could be exploited in pharmaceutical applications involving tissue engineering, wound repair, drug delivery, and cancer therapy. This review comprehensively discusses the advancements in the implementation of different formulations of silk fibroin and sericin in wound healing and drug delivery systems, particularly for cancer treatment.

Silk fibroin microgrooved zirconia surfaces improve connective tissue sealing through mediating glycolysis of fibroblasts

The use of zirconia has significantly enhanced the aesthetic outcomes of implant restorations. However, peri-implantitis remains a challenge to long-term functionality of implants. Unlike the perpendicularly arranged collagen fibers in periodontal tissue, those in peri-implant tissue lie parallel to the abutment surface and contain fewer fibroblasts, making them more prone to inflammation. Studies have shown that microgroove structures on implant abutments could improve surrounding soft tissue structure. However, creating precise microgrooves on zirconia without compromising its mechanical integrity is technically challenging. In this study, we applied inkjet printing, an additive manufacturing technique, to create stable silk fibroin microgroove (SFMG) coatings of various dimensions on zirconia substrates. SFMG significantly improved the hydrophilicity of zirconia and showed good physical and chemical stability. The SFMG with 90 μm interval and 10 μm depth was optimal in promoting the proliferation, alignment, and extracellular matrix production of human gingival fibroblasts (HGFs). Moreover, the in vitro results revealed that SFMG stimulated key glycolytic enzyme gene expression in HGFs via the PI3K-AKT-mTOR pathway. Additionally, the in vivo results of histological staining of peri-abutments soft tissue showed that SFMG promoted the vertical alignment of collagen fibers relative to the abutment surface, improving connective tissue sealing around the zirconia abutment. Our results indicated that SFMG on zirconia can enhance HGF proliferation, migration and collagen synthesis by regulating glycolysis though PI3K-AKT-mTor pathway, thereby improving connective tissue sealing.

Eco-Friendly Production of Polyvinyl Alcohol/Carboxymethyl Cellulose Wound Healing Dressing Containing Sericin

Wound dressing production represents an important segment in the biomedical healthcare field, but finding a simple and eco-friendly method that combines a natural compound and a biocompatible dressing production for biomedical application is still a challenge. Therefore, the aim of this study is to develop wound healing dressings that are environmentally friendly, low cost, and easily produced, using natural agents and a physical crosslinking technique. Hydrogel wound healing dressings were prepared from polyvinyl alcohol/carboxymethyl cellulose and sericin using the freeze-thawing method as a crosslinking method. The morphological characterization was carried out by scanning electron microscopy (SEM), whereas the mechanical analysis was carried out by dynamic mechanical analysis (DMA) to test the tensile strength and compression properties. Then, the healing property of the wound dressing material was tested by in vitro and ex vivo tests. The results show a three-dimensional microporous structure with no cytotoxicity, excellent stretchability with compressive properties similar to those of human skin, and excellent healing properties. The proposed hydrogel dressing was tested in vitro with HaCaT keratinocytes and ex vivo with epidermal tissues, demonstrating an effective advantage on wound healing acceleration. Accordingly, this study was successful in developing wound healing dressings using natural agents and a simple and green crosslinking method.

Silk fibroin-based dressings with antibacterial and anti-inflammatory properties

Silk fibroin is a fibrillar protein obtained from arthropods such as mulberry and non-mulberry silkworms. Silk fibroin has been used as a dressing in wound treatment for its physical, chemical, mechanical, and biological properties. This systematic review analyzed studies from PubMed, Web of Science, and Scopus databases to identify the molecules preferred for functionalizing silk fibroin-based dressings and to describe their mechanisms of exhibiting anti-inflammatory and antibacterial properties. The analysis of the selected articles allowed us to classify the dressings into different conformations, such as membranes, films, hydrogels, sponges, and bioadhesives. The incorporation of various molecules, including antibiotics, natural products, peptides, nanocomposites, nanoparticles, secondary metabolites, growth factors, and cytokines, has allowed the development of dressings that promote wound healing with antibacterial and immunomodulatory properties. In addition, silk fibroin-based dressings have been established to have the potential to regenerate wounds such as venous ulcers, arterial ulcers, diabetic foot, third-degree burns, and neoplastic ulcers. Evaluation of the efficacy of silk fibroin-based dressings in tissue engineering is an area of great activity that has shown significant advances in recent years.

A review of the current state of natural biomaterials in wound healing applications

Skin, the largest biological organ, consists of three main parts: the epidermis, dermis, and subcutaneous tissue. Wounds are abnormal wounds in various forms, such as lacerations, burns, chronic wounds, diabetic wounds, acute wounds, and fractures. The wound healing process is dynamic, complex, and lengthy in four stages involving cells, macrophages, and growth factors. Wound dressing refers to a substance that covers the surface of a wound to prevent infection and secondary damage. Biomaterials applied in wound management have advanced significantly. Natural biomaterials are increasingly used due to their advantages including biomimicry of ECM, convenient accessibility, and involvement in native wound healing. However, there are still limitations such as low mechanical properties and expensive extraction methods. Therefore, their combination with synthetic biomaterials and/or adding bioactive agents has become an option for researchers in this field. In the present study, the stages of natural wound healing and the effect of biomaterials on its direction, type, and level will be investigated. Then, different types of polysaccharides and proteins were selected as desirable natural biomaterials, polymers as synthetic biomaterials with variable and suitable properties, and bioactive agents as effective additives. In the following, the structure of selected biomaterials, their extraction and production methods, their participation in wound healing, and quality control techniques of biomaterials-based wound dressings will be discussed.

Evaluation of the Modification Effects of Heparin/Dalteparin on Silk Fibroin Structure and Physical Properties for Skin Wound Healing

We have developed a functionalized silk fibroin (BSF) that can serve as an improved fundamental material for dressings by specifically capturing growth factors secreted during the healing process and supplying them to cells accumulated in the wound area to enhance the tissue regeneration efficiency. When considering the design of heparin-modified BSF, there is a difficulty with binding to high-molecular-weight polysaccharides without disrupting the hydrophobic crystalline structure of the BSF. In this study, a low-molecular-weight pharmaceutical heparin, dalteparin, was selected and cross-linked with the tyrosine residue presence in the BSF non-crystalline region. When targeting 3D porous applications like nanofiber sheets, as it is crucial not only to enhance biological activity but also to improve handling by maintaining stability in water and mechanical strength, a trade-off between improved cell affinity and reduced mechanical strength depending on crystalline structure was evaluated. The use of dalteparin maintained the mechanical strength better than unfractionated heparin by reducing the effect on disturbing BSF recrystallization. Film surface hydrophilicity and cell proliferation induction were significantly higher in the dalteparin group. For BSF functionalization, using purified heparin was an effective approach that achieved a balance between preserving the mechanical properties and induction of tissue regeneration, offering the potential for various forms in the future.

Advances in the extracellular signal-regulated kinase signaling pathway in silkworms, Bombyx mori (Lepidoptera)

Signaling pathways regulate the transmission of signals during organism growth and development, promoting the smooth and accurate completion of numerous physiological and biochemical reactions. The extracellular signal-regulated kinase (ERK) signaling pathway is an essential pathway involved in regulating various physiological processes, such as cell proliferation, differentiation, adhesion, migration, and more. This pathway also contributes to several important physiological processes in silkworms, including protein synthesis, reproduction, and immune defense against pathogens. Organizing related studies on the ERK signaling pathway in silkworms can provide a better understanding of its mechanism in Lepidopterans and develop a theoretical foundation for improving cocoon production and new strategies for pest biological control.

Protein-modified nanomaterials: emerging trends in skin wound healing

Prolonged inflammation can impede wound healing, which is regulated by several proteins and cytokines, including IL-4, IL-10, IL-13, and TGF-β. Concentration-dependent effects of these molecules at the target site have been investigated by researchers to develop them as wound-healing agents by regulating signaling strength. Nanotechnology has provided a promising approach to achieve tissue-targeted delivery and increased effective concentration by developing protein-functionalized nanoparticles with growth factors (EGF, IGF, FGF, PDGF, TGF-β, TNF-α, and VEGF), antidiabetic wound-healing agents (insulin), and extracellular proteins (keratin, heparin, and silk fibroin). These molecules play critical roles in promoting cell proliferation, migration, ECM production, angiogenesis, and inflammation regulation. Therefore, protein-functionalized nanoparticles have emerged as a potential strategy for improving wound healing in delayed or impaired healing cases. This review summarizes the preparation and applications of these nanoparticles for normal or diabetic wound healing and highlights their potential to enhance wound healing.

Fabrication andin vitroevaluation of photo cross-linkable silk fibroin-epsilon-poly-L-lysine hydrogel for wound repair

An optimal wound-healing hydrogel requires effective antibacterial properties and a favorable cell adhesion and proliferation environment. AlthoughBombyx morisilk fibroin (SF) possesses inherent wound-healing properties, it lacks these essential qualities. This study aimed to fabricate a novel photo-polymerizable hydrogel by utilizing SF's wound-healing efficiency and the epsilon-poly-L-lysine (EPL) antimicrobial activity. The SF was modified with three different concentrations of glycidyl methacrylate (GMA) to obtain SF-GMA(L), SF-GMA(M), and SF-GMA(H). A methacrylated EPL (EPL-GMA) was also produced. Then, SF-GMA was mixed with EPL-GMA to produce photo-crosslinkable SF-GMA-EPL hydrogels. The SF-GMA(L)-EPL, SF-GMA(M)-EPL, and SF-GMA(H)-EPL hydrogels, fabricated with 20% EPL-GMA, demonstrated maximum antimicrobial activity and mammalian cell adhesion ability. The hydroxyl radical (•OH) scavenging efficiency of the hydrogels was tested and shown to be between 69% and 74%. These hydrogels also exhibited 60% efficiency in removing bacterial lipopolysaccharides. The water absorption ability of the hydrogels was consistent with the size of their internal pores. The hydrogels exhibited a slow degradation fashion, and their degradation products appeared cytocompatible. Finally, the elastomeric properties of the hydrogels were determined, and a storage modulus (G') of 300-600 Pa was demonstrated. In conclusion, the hydrogels created in this study possess excellent biological and physical properties to support wound healing.

Silk Fibroin and Sericin Differentially Potentiate the Paracrine and Regenerative Functions of Stem Cells Through Multiomics Analysis

Silk fibroin (SF) and sericin (SS), the two major proteins of silk, are attractive biomaterials with great potential in tissue engineering and regenerative medicine. However, their biochemical interactions with stem cells remain unclear. In this study, multiomics are employed to obtain a global view of the cellular processes and pathways of mesenchymal stem cells (MSCs) triggered by SF and SS to discern cell-biomaterial interactions at an in-depth, high-throughput molecular level. Integrated RNA sequencing and proteomic analysis confirm that SF and SS initiate widespread but distinct cellular responses and potentiate the paracrine functions of MSCs that regulate extracellular matrix deposition, angiogenesis, and immunomodulation through differentially activating the integrin/PI3K/Akt and glycolysis signaling pathways. These paracrine signals of MSCs stimulated by SF and SS effectively improve skin regeneration by regulating the behavior of multiple resident cells (fibroblasts, endothelial cells, and macrophages) in the skin wound microenvironment. Compared to SS, SF exhibits better immunomodulatory effects in vitro and in vivo, indicating its greater potential as a carrier material of MSCs for skin regeneration. This study provides comprehensive and reliable insights into the cellular interactions with SF and SS, enabling the future development of silk-based therapeutics for tissue engineering and stem cell therapy.

Photopolymerized silk fibroin gel for advanced burn wound care

The future of burn wound treatment lies in developing bioactive dressings for faster and more effective healing and regeneration. Silk fibroin (SF) hydrogels have proven regenerative abilities and are being explored as a burn wound dressing. However, unfavorable gelation conditions limit the processability and clinical application. Herein a white light-responsive photopolymerization technique was adapted for gelation via photooxidation of tyrosine. To render the gel suitable for application to irregular and non-planar burn surfaces, SF gel-incorporated dressing (SFD) was fabricated. The mild gelation conditions using white light afforded the loading of drugs for local delivery. The moisture balance ability of the dressing was confirmed by the favorable measures of swelling capacity (106 ± 1 %) and moisture retention (≈10 h). The in vitro cytocompatibility of the gel was confirmed using HaCaT cells. Finally, in vivo performance of the SFD was tested on a second-degree burn in a rodent model. The gross analysis and histological assessment revealed scarless healing in SFD-treated groups. Overall, the SFD developed in this work is shown to be a promising candidate for advanced burn wound care.

Drug/bioactive eluting chitosan composite foams for osteochondral tissue engineering

Joint defects associated with a variety of etiologies often extend deep into the subchondral bone leading to functional impairment and joint immobility, and it is a very challenging task to regenerate the bone-cartilage interface offering significant opportunities for biomaterial-based interventions to improve the quality of life of patients. Herein drug-/bioactive-loaded porous tissue scaffolds incorporating nano-hydroxyapatite (nHAp), chitosan (CS) and either hydroxypropyl methylcellulose (HPMC) or Bombyx mori silk fibroin (SF) are fabricated through freeze drying method as subchondral bone substitute. A combination of spectroscopy and microscopy (Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and X-ray fluorescence (XRF) were used to analyze the structure of the porous biomaterials. The compressive mechanical properties of these scaffolds are biomimetic of cancellous bone tissues and capable of releasing drugs/bioactives (exemplified with triamcinolone acetonide, TA, or transforming growth factor-β1, TGF-β1, respectively) over a period of days. Mouse preosteoblast MC3T3-E1 cells were observed to adhere and proliferate on the tissue scaffolds as confirmed by the cell attachment, live-dead assay and alamarBlue™ assay. Interestingly, RT-qPCR analysis showed that the TA downregulated inflammatory biomarkers and upregulated the bone-specific biomarkers, suggesting such tissue scaffolds have long-term potential for clinical application.

Highly stretchable porous regenerated silk fibroin film for enhanced wound healing

Silk fibroin (SF) has received interest in tissue engineering owing to its biocompatibility, biodegradability, and favorable mechanical properties. However, the complex preparation, brittleness, and lack of pores in the structure of the silk fibroin film limit its application. Herein, we show that facile dissolution of SF in aqueous phosphoric acid followed by regeneration in aqueous ammonium sulfate ((NH₄)₂SO₄) could afford highly stretchable films with nano-pores formed in the nonsolvent-induced phase separation process. The named phase separation, which determines the morphology and mechanical properties of the regeneration silk fibroin (RSF) films, is highly dependent on the (NH₄)₂SO₄ concentration as well as the initial concentration of the SF solution. Therefore, the RSF films exhibit a tunable pore size ranging from 230 to 510 nm and excellent stretchability with tensile strain up to 143 ± 16%. Most interestingly, the RSF films were shown to support the proliferation of human skin fibroblasts in vitro as well as speed up full-thickness skin wound healing in a rat model. This work establishes an easy and feasible method to access porous RSF membranes that can be used for wound dressing in clinical settings.

Sericin/Human Placenta-Derived Extracellular Matrix Scaffolds for Cutaneous Wound Treatment-Preparation, Characterization, In Vitro and In Vivo Analyses

Human placenta is loaded with an enormous amount of endogenous growth factors, thereby making it a superior biomaterial for tissue regeneration. Sericin is a naturally occurring silk protein that is extensively used for biomedical applications. In the present work, sericin and human placenta-derived extracellular matrix were blended and fabricated in the form of scaffolds using the freeze-drying method for cutaneous wound treatment. The prepared sericin/placenta-derived extracellular matrix (SPEM) scaffolds were characterized to determine their morphology, functional groups, mechanical strength, and antibacterial activity. Scanning electron microscopic analysis of the scaffolds showed smooth surfaces with interconnected pores. In vitro MTT and scratch wound assays performed using HaCaT cells proved the non-toxic and wound-healing efficacy of SPEM scaffolds. In vivo CAM assay using fertilized chick embryos proved the angiogenic potency of the scaffolds. Animal experiments using Wistar albino rats proved that the open excision wounds treated with SPEM scaffolds significantly reduced wound size with collagen deposition. These results confirm that SPEM scaffolds can serve as a promising biomaterial for tissue regeneration.

Delivering on the promise of recombinant silk-inspired proteins for drug delivery

Effective drug delivery is essential for the success of a medical treatment. Polymeric drug delivery systems (DDSs) are preferred over systemic administration of drugs due to their protection capacity, directed release, and reduced side effects. Among the numerous polymer sources, silks and recombinant silks have drawn significant attention over the past decade as DDSs. Native silk is produced from a variety of organisms, which are then used as sources or guides of genetic material for heterologous expression or engineered designs. Recombinant silks bear the outstanding properties of natural silk, such as processability in aqueous solution, self-assembly, drug loading capacity, drug stabilization/protection, and degradability, while incorporating specific properties beneficial for their success as DDS, such as monodispersity and tailored physicochemical properties. Moreover, the on-demand inclusion of sequences that customize the DDS for the specific application enhances efficiency. Often, inclusion of a drug into a DDS is achieved by simple mixing or diffusion and stabilized by non-specific molecular interactions; however, these interactions can be improved by the incorporation of drug-binding peptide sequences. In this review we provide an overview of native sources for silks and silk sequences, as well as the design and formulation of recombinant silk biomaterials as drug delivery systems in a variety of formats, such as films, hydrogels, porous sponges, or particles.

Antioxidation and anti-inflammatory effects of gamma-irradiated silk sericin and fibroin in H2O2-induced HaCaT Cell

Oxidative stress in skin cells can induce the formation of reactive oxygen species (ROS), which are critical for pathogenic processes such as immunosuppression, inflammation, and skin aging. In this study, we confirmed improvements from gamma-irradiated silk sericin (I-sericin) and gamma-irradiated silk fibroin (I-fibroin) to skin cells damaged by oxidative stress. We found that I-sericin and I-fibroin effectively attenuated oxidative stress-induced ROS generation and decreased oxidative stress-induced inflammatory factors COX-2, iNOS, tumor necrosis factor-α, and interleukin-1β compared to the use of non-irradiated sericin or fibroin. I-sericin and I-fibroin effects were balanced by competition with skin regenerative protein factors reacting to oxidative stress. Taken together, our results indicated that, compared to non-irradiated sericin or fibroin, I-sericin, and I-fibroin had anti-oxidation and anti-inflammation activity and protective effects against skin cell damage from oxidative stress. Therefore, gamma-irradiation may be useful in the development of cosmetics to maintain skin health.

Silk Fibroin Biomaterials and Their Beneficial Role in Skin Wound Healing

The skin, acting as the outer protection of the human body, is most vulnerable to injury. Wound healing can often be impaired, leading to chronic, hard-to-heal wounds. For this reason, searching for the most effective dressings that can significantly enhance the wound healing process is necessary. In this regard, silk fibroin, a protein derived from silk fibres that has excellent properties, is noteworthy. Silk fibroin is highly biocompatible and biodegradable. It can easily make various dressings, which can be loaded with additional substances to improve healing. Dressings based on silk fibroin have anti-inflammatory, pro-angiogenic properties and significantly accelerate skin wound healing, even compared to commercially available wound dressings. Animal studies confirm the beneficial influence of silk fibroin in wound healing. Clinical research focusing on fibroin dressings is also promising. These properties make silk fibroin a remarkable natural material for creating innovative, simple, and effective dressings for skin wound healing. In this review, we summarise the application of silk fibroin biomaterials as wound dressings in full-thickness, burn, and diabetic wounds in preclinical and clinical settings.

Bioengineered and functionalized silk proteins accelerate wound healing in rat and human dermal fibroblasts

Wound healing is an intrinsic process directed towards the restoration of damaged or lost tissue. The development of a dressing material having the ability to control the multiple aspects of the wound environment would be an ideal strategy to improve wound healing. Though natural silk proteins, fibroin, and sericin have demonstrated tissue regenerative properties, the efficacy of bioengineered silk proteins on wound healing is seldom assessed. Furthermore, silk proteins sans contaminants, having low molecular masses, and combining with other bioactive factors can hasten the wound healing process. Herein, recombinant silk proteins, fibroin and sericin, and their fusions with cecropin B were evaluated for their wound-healing effects using in vivo rat model. The recombinant silk proteins demonstrated accelerated wound closure in comparison to untreated wounds and treatment with Povidone. Among all groups, the treatment with recombinant sericin-cecropin B (RSC) showed significantly faster healing, greater than 90% wound closure by Day 12 followed by recombinant fibroin-cecropin B (RFC) (88.86%). Furthermore, histological analysis and estimation of hydroxyproline showed complete epithelialization, neovascularization, and collagenisation in groups treated with recombinant silk proteins. The wound healing activity was further verified by in vitro scratch assay using HADF cells, where the recombinant silk proteins induced cell proliferation and cell migration to the wound area. Additionally, wound healing-related gene expression showed recombinant silk proteins stimulated the upregulation of EGF and VEGF and regulated the expression of TGF-β1 and TGF-β3. Our results demonstrated the enhanced healing effects of the recombinant silk fusion proteins in facilitating complete tissue regeneration with scar-free healing. Therefore, the recombinant silks and their fusion proteins have great potential to be developed as smart bandages for wound healing.

Green tea catechin-grafted silk fibroin hydrogels with reactive oxygen species scavenging activity for wound healing applications

BACKGROUND

Overproduction of reactive oxygen species (ROS) is known to delay wound healing by causing oxidative tissue damage and inflammation. The green tea catechin, (-)-Epigallocatechin-3-O-gallate (EGCG), has drawn a great deal of interest due to its strong ROS scavenging and anti-inflammatory activities. In this study, we developed EGCG-grafted silk fibroin hydrogels as a potential wound dressing material.

METHODS

The introduction of EGCG to water-soluble silk fibroin (SF-WS) was accomplished by the nucleophilic addition reaction between lysine residues in silk proteins and EGCG quinone at mild basic pH. The resulting SF-EGCG conjugate was co-crosslinked with tyramine-substituted SF (SF-T) via horseradish peroxidase (HRP)/H2O2 mediated enzymatic reaction to form SF-T/SF-EGCG hydrogels with series of composition ratios.

RESULTS

Interestingly, SF-T70/SF-EGCG30 hydrogels exhibited rapid in situ gelation (< 30 s), similar storage modulus to human skin (≈ 1000 Pa) and superior wound healing performance over SF-T hydrogels and a commercial DuoDERM® gel dressings in a rat model of full thickness skin defect.

CONCLUSION

This study will provide useful insights into a rational design of ROS scavenging biomaterials for wound healing applications.

Construction and properties of the silk fibroin and polypropylene composite biological mesh for abdominal incisional hernia repair

Background: In this study, a new composite biological mesh named SFP was prepared by combining silk fibroin with polypropylene mesh. The mechanism and clinical application value of the SFP composite mesh were explored.

Methods: The fibrous membrane was prepared by electrospinning of silk fibroin. The silk fibrous membrane was adhered to the polypropylene mesh by fibrin hydrogel to make a new composite mesh. The characterizations were verified by structural analysis and in vitro cell experiments. A total of 40 Sprague–Dawley rats were randomly divided into two groups, and 20 rats in each group were implanted with the SFP mesh and pure polypropylene mesh, respectively. The rats were sacrificed in batches on the 3rd, 7th, 14th, and 90th days after surgery. The adhesion degree and adhesion area on the mesh surface were compared, and a histopathological examination was carried out.

Results:In vitro cell function experiments confirmed that the SFP mesh had good cell viability. The control group had different degrees of adhesion on the 3rd, 7th, 14th, and 90th days after surgery. However, there was almost no intraperitoneal adhesions on the 3rd and 7th days after surgery, and some rats only had mild adhesions on the 14th and 90th days after surgery in the SFP group. There were statistically significant differences in the postoperative intraperitoneal adhesion area and adhesion degree between the two groups (p < 0.05). Histopathological examination confirmed that the mesenchymal cells were well arranged and continuous, and there were more new capillaries and adipocyte proliferation under the mesenchymal cells in the SFP group.

Conclusion: The SFP mesh shows good biocompatibility and biofunction in vitro and in vivo. It can promote the growth of peritoneal mesenchymal cells. The formation of a new mesenchymal cell layer can effectively reduce the extent and scope of adhesion between the mesh and abdominal organs. The SFP mesh will have a good application prospect in the field of abdominal wall hernia repair.

A Bioengineering Approach for the Development of Fibroblast Growth Factor-7-Functionalized Sericin Biomaterial Applicable for the Cultivation of Keratinocytes

Growth factors, including fibroblast growth factor-7 (FGF-7), are a group of proteins that stimulate various cellular processes and are often used with carriers to prevent the rapid loss of their activities. Sericin with great biocompatibility has been investigated as a proteinaceous carrier to enhance the stability of incorporated proteins. The difficulties in obtaining intact sericin from silkworm cocoons and the handling of growth factors with poor stability necessitate an efficient technique to incorporate the protein into a sericin-based biomaterial. Here, we report the generation of a transgenic silkworm line simultaneously expressing and incorporating FGF-7 into cocoon shells containing almost exclusively sericin. Growth-factor-functionalized sericin cocoon shells requiring simple lyophilization and pulverization processes were successfully used to induce the proliferation and migration of keratinocytes. Moreover, FGF-7 incorporated into sericin-cocoon powder exhibited remarkable stability, with more than 70% of bioactivity being retained after being stored as a suspension at 25 °C for 3 months. Transgenic sericin-cocoon powder was used to continuously supply biologically active FGF-7 to generate a three-dimensionally cultured keratinocyte model in vitro. The outcomes of this study propound a feasible approach to producing cytokine-functionalized sericin materials that are ready to use for cell cultivation.

The proteomics of the freshwater pearl powder: Insights from biomineralization to biomedical application

The freshwater pearl is one kind of valuable organic jewelry and traditional Chinese medicine (TCM). However, the molecular basis of matrix protein in pearl biomineralization and biomedical applications are largely unknown to date. In this study, the matrix proteins of water-soluble matrix, acid-soluble matrix and acid-insoluble matrix from the freshwater seedless pearl powder were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) respectively, and identified against the transcriptomic database of the pearl sac. The results showed that a total of 190 proteins were identified in pearl proteomics, which was divided into eight categories by their potential biomineralization functions. The composition of pearl matrix proteins and the high frequency conserved domains like carbonic anhydrase, von Willebrand factor type A, tyrosinase and chitin binding 2 in protein sequences, implying that the "chitin-silk fibroin gel proteins-acidic macromolecules" model was suitable for description the pearl biomineralization process. Meanwhile, ninety-one of pearl matrix proteins could be classified into seven categories by their potential medical functions including wound healing, osteogenic property, antioxidant activity, neuro-regulation effects, skin lightening effect, anti-inflammatory and anti-apoptotic effects and other immunomodulatory property. In general, these results provided valuable new insights into not only the diversity of pearl matrix protein for mollusc biomineralization, but the molecular basis of pearl matrix proteins responsible for their diverse biological properties in TCM application. SIGNIFICANCE: The significance of this study included the following points.

Bilayer silk fibroin/sodium alginate scaffold promotes vascularization and advances inflammation stage in full-thickness wound

An ideal wound dressing for full-thickness wound regeneration should offer desirable biocompatibility, adequate mechanical properties, barrier function, and cellular regulation. Here, a bilayer scaffold resembling the hierarchical structure of human skin was developed using silk fibroin and sodium alginate. The upper membrane was prepared through casting and functioned as the epidermis, whereas the lower porous scaffold was prepared by freeze-drying and mimicked extracellular matrix structures. The membrane had nonporous structure, desirable mechanical properties, moderate hydrophilic surface, and suitable water vapor transmission rate, whereas the porous scaffold revealed 157.61 ± 41.67 µm pore size, 86.10 ± 3.60% porosity, and capability of stimulating fibroblast proliferation. The combination of the two structures reinforced the tensile strength by 5-fold and provided protection from wound dehydration. A suitable degradation rate reduced potential administration frequency. Furthermore, an in vivo rabbit full-thickness wound healing test demonstrated that the bilayer scaffold facilitated wound closure, granulation tissue formation, re-epithelialization and skin component transition towards normal skin by providing a moist wound environment, advancing the inflammation stage, and stimulating angiogenesis. Collectively, as an off-the-shelf and cell-free wound dressing with single topical administration, the bilayer scaffold is a promising wound dressing for full-thickness wound regeneration.

Biomimetic Design and Fabrication of Sericin-Hydroxyapatite Based Membranes With Osteogenic Activity for Periodontal Tissue Regeneration

The guided tissue regeneration (GTR) technique is a promising treatment for periodontal tissue defects. GTR membranes build a mechanical barrier to control the ingrowth of the gingival epithelium and provide appropriate space for the regeneration of periodontal tissues, particularly alveolar bone. However, the existing GTR membranes only serve as barriers and lack the biological activity to induce alveolar bone regeneration. In this study, sericin-hydroxyapatite (Ser-HAP) composite nanomaterials were fabricated using a biomimetic mineralization method with sericin as an organic template. The mineralized Ser-HAP showed excellent biocompatibility and promoted the osteogenic differentiation of human periodontal membrane stem cells (hPDLSCs). Ser-HAP was combined with PVA using the freeze/thaw method to form PVA/Ser-HAP membranes. Further studies confirmed that PVA/Ser-HAP membranes do not affect the viability of hPDLSCs. Moreover, alkaline phosphatase (ALP) staining, alizarin red staining (ARS), and RT-qPCR detection revealed that PVA/Ser-HAP membranes induce the osteogenic differentiation of hPDLSCs by activating the expression of osteoblast-related genes, including ALP, Runx2, OCN, and OPN. The unique GTR membrane based on Ser-HAP induces the differentiation of hPDLSCs into osteoblasts without additional inducers, demonstrating the excellent potential for periodontal regeneration therapy.

The Contribution of Silk Fibroin in Biomedical Engineering

Silk fibroin (SF) is a natural protein (biopolymer) extracted from the cocoons of Bombyx mori L. (silkworm). It has many properties of interest in the field of biotechnology, the most important being biodegradability, biocompatibility and robust mechanical strength with high tensile strength. SF is usually dissolved in water-based solvents and can be easily reconstructed into a variety of material formats, including films, mats, hydrogels, and sponges, by various fabrication techniques (spin coating, electrospinning, freeze-drying, and physical or chemical crosslinking). Furthermore, SF is a feasible material used in many biomedical applications, including tissue engineering (3D scaffolds, wounds dressing), cancer therapy (mimicking the tumor microenvironment), controlled drug delivery (SF-based complexes), and bone, eye and skin regeneration. In this review, we describe the structure, composition, general properties, and structure-properties relationship of SF. In addition, the main methods used for ecological extraction and processing of SF that make it a green material are discussed. Lastly, technological advances in the use of SF-based materials are addressed, especially in healthcare applications such as tissue engineering and cancer therapeutics.

Impact of silk hydrogel secondary structure on hydrogel formation, silk leaching and in vitro response

Silk can be processed into a broad spectrum of material formats and is explored for a wide range of medical applications, including hydrogels for wound care. The current paradigm is that solution-stable silk fibroin in the hydrogels is responsible for their therapeutic response in wound healing. Here, we generated physically cross-linked silk fibroin hydrogels with tuned secondary structure and examined their ability to influence their biological response by leaching silk fibroin. Significantly more silk fibroin leached from hydrogels with an amorphous silk fibroin structure than with a beta sheet-rich silk fibroin structure, although all hydrogels leached silk fibroin. The leached silk was biologically active, as it induced vitro chemokinesis and faster scratch assay wound healing by activating receptor tyrosine kinases. Overall, these effects are desirable for wound management and show the promise of silk fibroin and hydrogel leaching in the wider healthcare setting.

Restorative and pain-relieving effects of fibroin in preclinical models of tendinopathy

The term tendinopathy indicates a wide spectrum of conditions characterized by alterations in tendon tissue homeostatic response and damage to the extracellular matrix. The current pharmacological approach involves the use of nonsteroidal anti-inflammatory drugs and corticosteroids often with unsatisfactory results, making essential the identification of new treatments. In this study, the pro-regenerative and protective effects of an aqueous fibroin solution (0.5-500 μg/mL) against glucose oxidase (GOx)-induced damage in rat tenocytes were investigated. Then, fibroin anti-hyperalgesic and protective actions were evaluated in two models of tendinopathy induced in rats by collagenase or carrageenan injection, respectively. In vitro, 5-10 μg/mL fibroin per se increased cell viability and reverted the morphological alterations caused by GOx (0.1 U/mL). Fibroin 10 μg/mL evoked proliferative signaling upregulating the expression of decorin, scleraxin, tenomodulin (p < 0.001), FGF-2, and tenascin-C (p < 0.01) genes. Fibroin enhanced the basal FGF-2 and MMP-9 protein concentrations and prevented their GOx-mediated decrease. Furthermore, fibroin positively modulated the production of collagen type I. In vivo, the peri-tendinous injection of fibroin (5 mg) reduced the development of spontaneous pain and hypersensitivity (p < 0.01) induced by the intra-tendinous injection of collagenase; the efficacy was comparable to that of triamcinolone. The pain-relieving action of fibroin (peri-tendinous) was confirmed in the model of tendinopathy induced by carrageenan (intra-tendinous) where this fibrous protein was also able to improve tendon matrix organization, normalizing the orientation of collagen fibers. In conclusion, the use of fibroin in tendinopathies is suggested taking advantage of its excellent mechanical properties, pain-relieving effects, and ability to promote tissue regeneration processes.

Cutaneous Regeneration Mechanism of β-Sheet Silk Fibroin in a Rat Burn Wound Healing Model

Therapeutic dressings to enhance burn wound repair and regeneration are required. Silk fibroin (SF), a natural protein, induces cell migration and serves as a biomaterial in various dressings. SF dressings usually contain α-helices and β-sheets. The former has been confirmed to improve cell proliferation and migration, but the wound healing effect and related mechanisms of β-sheet SF remain unclear. We investigated the effects of β-sheet SF in vivo and in vitro. Alcohol-treated α-helix SF transformed into the β-sheet form, which promoted granulation formation and re-epithelialization when applied as lyophilized SF dressing (LSFD) in a rat burn model. Our in vitro results showed that β-sheet SF increased human dermal fibroblast (HDF) migration and promoted the expression of extracellular matrix (ECM) proteins (fibronectin and type III collagen), matrix metalloproteinase-12, and the cell adhesion molecule, integrin β1, in rat granulation tissue and HDFs. This confirms the role of crosstalk between integrin β1 and ECM proteins in cell migration. In summary, we demonstrated that β-sheet SF facilitates tissue regeneration by modulating cell adhesion molecules in dermal fibroblasts. LSFD could find clinical application for burn wound regeneration. Moreover, β-sheet SF could be combined with anti-inflammatory materials, growth factors, or antibiotics to develop novel dressings.

Silk Fibroin: A Promising Tool for Wound Healing and Skin Regeneration

Silk is a functional protein biomaterial produced by a variety of insects like flies, silkworms, scorpions, spiders, and mites. Silk synthesized by silkworms is extensively studied for its applications in tissue engineering and wound healing. Silk is undoubtedly a natural biocompatible material with humans and has its role in medical treatments from ancient times. The silk worm protein comprises two types of proteins namely fibroin and sericin. Silk fibroin makes up approximately 70% of cocoon weight and has wide applications in textiles and in all biomedical applications owing to its biocompatible, nontoxic, biodegradable, less immunogenic, and noncarcinogenic nature. It possesses outstanding toughness and mechanical strength, while silk sericin possesses high defensive ability against ultraviolet light and oxidation. Silk fibroin has been known to induce wound healing by increasing cell proliferation and growth and migrating various types of cells which are involved in different stages of wound healing process. With several silk varieties like silk worm fibroin, silk sericin, recombinant silk materials, and native spider silk have been investigated for its wound healing applications over the last several decades. With an objective of harnessing the silk regenerative properties, plentiful strategies have been studied and applied to develop bioartificial skin grafts and bioactive wound dressings in recent times. This review gives a detailed insight into the structure, general properties, fibroin structure-properties relationship, and biomedical applications of silk fibroin.

Photocrosslinking silver nanoparticles-aloe vera-silk fibroin composite hydrogel for treatment of full-thickness cutaneous wounds

Damage to the skin causes physiological and functional issues. The most effective treatment approach is the use of wound dressings. Silk fibroin (SF) is a promising candidate biomaterial for regulating wound healing; however, its antibacterial properties and biological activity must be further improved. In this study, a photocrosslinking hydrogel was developed to treat full-thickness cutaneous wounds. The composite hydrogel (Ag–AV–SF hydrogel) was prepared by introducing the silver nanoparticles (AgNPs) and aloe vera (AV) as the modifiers. In vitro study exhibited great antibacterial ability, biocompatibility and cell-proliferation and -migration-promoting capacities. It also showed the pH-response releasing properties which release more AgNPs in a simulated chronic infection environment. The healing effect evaluation in vivo showed the healing-promoting ability of the Ag–AV–SF hydrogel was stronger than the single-modifiers groups, and the healing rate of it reached 97.02% on Day 21, higher than the commercial wound dressing, silver sulfadiazine (SS) cream on sale. Additionally, the histological and protein expression results showed that the Ag–AV–SF hydrogel has a greater effect on the pro-healing regenerative phenotype with M2 macrophages at the early stage, reconstructing the blood vessels networks and inhibiting the formation of scars. In summary, the Ag–AV–SF hydrogel developed in this study had good physical properties, overwhelming antibacterial properties, satisfactory biocompatibility and significantly promoting effect on cell proliferation, migration and wound healing. Overall, our results suggest that the Ag–AV–SF hydrogel we developed has great potential for improving the wound healing in clinical treatment.

Alternative to FBS in animal cell culture - An overview and future perspective

Fetal bovine serum (FBS) is a widely used growth supplement in the in vitro culturing of animal and human cells, tissues and organs, notably due to the occurrence of abundant micro- and macronutrients, along with growth factors. Over the years, increasing demand, high price, batch-to-batch variability in quality and composition, increasing ethical concerns lead to the search for an alternative to FBS. Several approaches have been suggested and employed in the past, but none is implemented as widely as FBS, and each supplement has its own disadvantages. In this review, we described the importance of FBS in cell culture, discussed the issues associated with FBS use and presented the efforts made in the recent past to reduce or replace FBS. The potential of four different alternative sources to FBS, namely, bovine ocular fluid, sericin protein, human platelet lysate and earthworm heat inactivated coelomic fluid was evaluated. In the end, we present the conceptual perspective using the Human Platelet Lysate (HPL) and earthworm Heat Inactivated Coelomic Fluid (HI-CF) combination to alternate FBS and its context in scientific and economic impacts.

Local drug delivery systems as therapeutic strategies against periodontitis: A systematic review

Periodontitis is a chronic inflammation of the soft tissue surrounding and supporting the teeth, which causes periodontal structural damage, alveolar bone resorption, and even tooth loss. Its prevalence is very high, with nearly 60% of the global population affected. Hence, periodontitis is an important public health concern, and the development of effective healing treatments for oral diseases is a major target of the health sciences. Currently, the application of local drug delivery systems (LDDS) as an adjunctive therapy to scaling and root planning (SRP) in periodontitis is a promising strategy, giving higher efficacy and fewer side effects by controlling drug release. The cornerstone of successful periodontitis therapy is to select an appropriate bioactive agent and route of administration. In this context, this review highlights applications of LDDS with different properties in the treatment of periodontitis with or without systemic diseases, in order to reveal existing challenges and future research directions.

Bioactive potential of natural biomaterials: identification, retention and assessment of biological properties

Biomaterials have had an increasingly important role in recent decades, in biomedical device design and the development of tissue engineering solutions for cell delivery, drug delivery, device integration, tissue replacement, and more. There is an increasing trend in tissue engineering to use natural substrates, such as macromolecules native to plants and animals to improve the biocompatibility and biodegradability of delivered materials. At the same time, these materials have favourable mechanical properties and often considered to be biologically inert. More importantly, these macromolecules possess innate functions and properties due to their unique chemical composition and structure, which increase their bioactivity and therapeutic potential in a wide range of applications. While much focus has been on integrating these materials into these devices via a spectrum of cross-linking mechanisms, little attention is drawn to residual bioactivity that is often hampered during isolation, purification, and production processes. Herein, we discuss methods of initial material characterisation to determine innate bioactivity, means of material processing including cross-linking, decellularisation, and purification techniques and finally, a biological assessment of retained bioactivity of a final product. This review aims to address considerations for biomaterials design from natural polymers, through the optimisation and preservation of bioactive components that maximise the inherent bioactive potency of the substrate to promote tissue regeneration.

Sericin based nanoformulations: a comprehensive review on molecular mechanisms of interaction with organisms to biological applications

BACKGROUND

The advances in products based on nanotechnology have directed extensive research on low-cost, biologically compatible, and easily degradable materials.

MAIN BODY

Sericin (SER) is a protein mainly composed of glycine, serine, aspartic acid, and threonine amino acids removed from the silkworm cocoon (particularly Bombyx mori and other species). SER is a biocompatible material with economic viability, which can be easily functionalized due to its potential crosslink reactions. Also, SER has inherent biological properties, which makes possible its use as a component of pharmaceutical formulations with several biomedical applications, such as anti-tumor, antimicrobials, antioxidants and as scaffolds for tissue repair as well as participating in molecular mechanisms attributed to the regulation of transcription factors, reduction of inflammatory signaling molecules, stimulation of apoptosis, migration, and proliferation of mesenchymal cells.

CONCLUSION

In this review, the recent innovations on SER-based nano-medicines (nanoparticles, micelles, films, hydrogels, and their hybrid systems) and their contributions for non-conventional therapies are discussed considering different molecular mechanisms for promoting their therapeutic applications.

Sericin based nanoformulations: a comprehensive review on molecular mechanisms of interaction with organisms to biological applications

BACKGROUND

The advances in products based on nanotechnology have directed extensive research on low-cost, biologically compatible, and easily degradable materials.

MAIN BODY

Sericin (SER) is a protein mainly composed of glycine, serine, aspartic acid, and threonine amino acids removed from the silkworm cocoon (particularly Bombyx mori and other species). SER is a biocompatible material with economic viability, which can be easily functionalized due to its potential crosslink reactions. Also, SER has inherent biological properties, which makes possible its use as a component of pharmaceutical formulations with several biomedical applications, such as anti-tumor, antimicrobials, antioxidants and as scaffolds for tissue repair as well as participating in molecular mechanisms attributed to the regulation of transcription factors, reduction of inflammatory signaling molecules, stimulation of apoptosis, migration, and proliferation of mesenchymal cells.

CONCLUSION

In this review, the recent innovations on SER-based nano-medicines (nanoparticles, micelles, films, hydrogels, and their hybrid systems) and their contributions for non-conventional therapies are discussed considering different molecular mechanisms for promoting their therapeutic applications.

Silk derived formulations for accelerated wound healing in diabetic mice

BACKGROUND

The present study aimed to prepare effective silk derived formulations in combination with plant extract (Aloe vera gel) to speed up the wound healing process in diabetic mice.

METHODS

Diabetes was induced in albino mice by using alloxan monohydrate. After successful induction of diabetes in mice, excision wounds were created via biopsy puncture (6 mm). Wound healing effect of silk sericin (5%) and silk fibroin (5%) individually and in combination with 5% Aloe vera gel was evaluated by determining the percent wound contraction, healing time and histological analysis.

RESULTS

The results indicated that the best biocompatible silk combination was of 5% silk fibroin and 5% Aloe vera gel in which wounds were healed in 13 days with wound contraction: 98.33 ± 0.80%. In contrast, the wound of the control group (polyfax) healed in 19 day shaving 98.5 ± 0.67% contraction. Histological analysis revealed that the wounds which were treated with silk formulations exhibited an increased growth of blood vessels, collagen fibers, and much reduced inflammation.

CONCLUSION

It can be concluded that a combination of Bombyx mori silk and Aloe vera gel is a natural biomaterial that can be utilized in wound dressings and to prepare more innovative silk based formulations for speedy recovery of chronic wounds.

Sericin for Tissue Engineering

Sericin is a 10-to-400 kDa hydrophilic protein with high serine content and is a silk constituent together with fibroin. It is produced in the middle silk gland of the silkworm and encoded by four sericin genes. The molecular weight of sericin and its biological activity vary depending on the extraction method employed. Its chemical structure, in terms of random coil and β-sheet conformations, also differs with the extraction method, thereby extending its applications in various fields. Sericin, which was discarded in the textile industry in the past, is being applied and developed in the biomedical field, owing to its biological properties. In particular, many studies are underway in the field of tissue engineering, evaluating its applicability in burn dressing, drug delivery, bone regeneration, cartilage regeneration, and nerve regeneration.

Comprehensive Review of Hybrid Collagen and Silk Fibroin for Cutaneous Wound Healing

The use of hybridisation strategy in biomaterials technology provides a powerful synergistic effect as a functional matrix. Silk fibroin (SF) has been widely used for drug delivery, and collagen (Col) resembles the extracellular matrix (ECM). This systematic review was performed to scrutinise the outcome of hybrid Col and SF for cutaneous wound healing. This paper reviewed the progress of related research based on in vitro and in vivo studies and the influence of the physicochemical properties of the hybrid in wound healing. The results indicated the positive outcome of hybridising Col and SF for cutaneous wound healing. The hybridisation of these biomaterials exhibits an excellent moisturising property, perfectly interconnected structure, excellent water absorption and retention capacity, an acceptable range of biodegradability, and synergistic effects in cell viability. The in vitro and in vivo studies clearly showed a promising outcome in the acceleration of cutaneous wound healing using an SF and Col hybrid scaffold. The review of this study can be used to design an appropriate hybrid scaffold for cutaneous wound healing. Therefore, this systematic review recapitulated that the hybridisation of Col and SF promoted rapid cutaneous healing through immediate wound closure and reepithelisation, with no sign of adverse events. This paper concludes on the need for further investigations of the hybrid SF and Col in the future to ensure that the hybrid biomaterials are well-suited for human skin.

Silk biomaterials in wound healing and skin regeneration therapeutics: From bench to bedside

Silk biomaterials are known for biomedical and tissue engineering applications including drug delivery and implantable devices owing to their biocompatible and a wide range of ideal physico-chemical properties. Herein, we present a critical overview of the progress of silk-based matrices in skin regeneration therapeutics with an emphasis on recent innovations and scientific findings. Beginning with a brief description of numerous varieties of silks, the review summarizes our current understanding of the biological properties of silk that help in the wound healing process. Various silk varieties such as silkworm silk fibroin, silk sericin, native spider silk and recombinant silk materials have been explored for cutaneous wound healing applications from the past few decades. With an aim to harness the regenerative properties of silk, numerous strategies have been applied to develop functional bioactive wound dressings and viable bio-artificial skin grafts in recent times. The review examines multiple inherent properties of silk that aid in the critical events of the healing process such as cell migration, cell proliferation, angiogenesis, and re-epithelialization. A detailed insight into the progress of silk-based cellular skin grafts is also provided that discusses various co-culture strategies and development of bilayer and tri-layer human skin equivalent under in vitro conditions. In addition, functionalized silk matrices loaded with bioactive molecules and antibacterial compounds are discussed, which have shown great potential in treating hard-to-heal wounds. Finally, clinical studies performed using silk-based translational products are reviewed that validate their regenerative properties and future applications in this area. STATEMENT OF SIGNIFICANCE: The review article discusses the recent advances in silk-based technologies for wound healing applications, covering various types of silk biomaterials and their properties suitable for wound repair and regeneration. The article demonstrates the progress of silk-based matrices with an update on the patented technologies and clinical advancements over the years. The rationale behind this review is to highlight numerous properties of silk biomaterials that aid in all the critical events of the wound healing process towards skin regeneration. Functionalization strategies to fabricate silk dressings containing bioactive molecules and antimicrobial compounds for drug delivery to the wound bed are discussed. In addition, a separate section describes the approaches taken to generate living human skin equivalent that have recently contributed in the field of skin tissue engineering.

Chemoprevention of Experimental Periodontitis in Diabetic Rats with Silk Fibroin Nanoparticles Loaded with Resveratrol

Objective: the objective of the present work is to study the effectiveness of treatment with silk fibroin nanoparticles loaded with resveratrol in experimental periodontitis in a diabetic rat model. Introduction: Periodontitis is an inflammatory pathology highly related to other diseases, such as type II diabetes. Both diseases have a specific inflammatory condition, with Interleukin (IL)-6, IL-1β and Transforming Grow Factor (TGF)-1β being the most relevant proinflammatory factors. Silk fibroin (SF) nanoparticles loaded with resveratrol (Res-SFN) are a new alternative as a treatment. Methods: 40 diabetic Sprague Dawley male rats were used and periodontitis was induced by ligation. The animals were divided into 5 treatment groups, and 1 mL of treatment was administered once a day for 4 weeks. The groups were: I: Carboxymethyl cellulose (CMC) 0.8%, II: CMC 0.8% + SF 1%, III: CMC 0.8% + RES-SFN 3 mg/mL, IV: CMC 0.8% + SF 1% + RES-SFN 3 mg/mL, V: Water. A peripheral blood sample was taken every week to quantify the inflammatory profile by ELISA (IL-6, IL-1β and TGF-1β). After 4 weeks the sacrifice was carried out and biopsies of the gum were taken. Results: Treatment with SF and RES-SFN reduced the amount of chemical inflammation mediators (with the exception of IL-1β in comparisons I-IV and II-IV (p > 0.05)), as well as the anatomopathological variables linked to it, in a significant way (p < 0.05). Conclusion: treatment with RES-SFN has reduced local inflammation in this experimental periodontitis model.

Porous Poly(Hexamethylene Biguanide) Hydrochloride Loaded Silk Fibroin Sponges with Antibacterial Function

In order to endue silk fibroin (SF) sponges with antibacterial function, positively charged poly(hexamethylene biguanide) hydrochloride (PHMB) was incorporated in SF through electrostatic interaction and by freeze-drying technique. The influence of PHMB on the structure and antibacterial activities of SF sponges was investigated. The zeta potential of SF was increased significantly when PHMB was incorporated in SF. The pores with size from 80 to 300 µm and the microscale holes in the pore walls within PHMB-loaded SF sponges provided the channels of PHMB release. The PHMB loaded in the porous sponges showed continuous and slow release for up to 20 days. Effective growth inhibition of both Escherichia coli and Staphylococcus aureus was achieved when the mass ratio of PHMB/SF was higher than 2/100. These results suggest that the porous PHMB/SF sponges have the potential to be used as a novel wound dressing for open skin wounds.

Gentisic Acid Stimulates Keratinocyte Proliferation through ERK1/2 Phosphorylation

Keratinocyte proliferation is important for skin wound healing. The wound healing process includes blood clotting around the wound, removal of dead cells and pathogens through inflammation, and then re-epithelialization through proliferation and maturation. Proliferation assay was performed on acid natural compounds to identify candidates for natural-derived components of skin injury treatment. We found that gentisic acid promoted high cell proliferation activity compared with other compounds. Gentisic acid improved HaCaT cell proliferation by over 20% in MTT assay. Gentisic acid also had higher healing activity in an in vitro wound healing assay than allantoin as a positive control. Furthermore, we have identified how the treatment of gentisic acid can increase proliferation in the cell. Western blot analysis of proteins in the mitogen-activated protein (MAP) kinase signaling pathway showed that ERK1/2 phosphorylation was increased by gentisic acid treatment. Thus, our study indicates that gentisic acid promotes the proliferation of keratinocyte by phosphorylation of ERK1/2.