Silk sericin ameliorates wound healing and its clinical efficacy in burn wounds

Biomedical applications ofBombyx morisilk in skin regeneration and cutaneous wound healing

A mere glance at the foundation of the sericulture industry to produce silk and the consequent establishment of the Silk Road to transport it; elucidates the significant role that this material has played in human history. Owing to its exceptional robustness, silk was introduced into medicine as a surgical suture approximately two millennia ago. During the last decades, silk has garnered attention as a possible source of biological-based materials that can be effectively used in regenerative medicine. Silk's unique characteristics, like its low immunogenicity, suitable adhesive properties, exceptional tensile strength, perfect hemostatic properties, adequate permeability to oxygen and water, resistance to microbial colonization, and most importantly, excellent biodegradability; make it an outstanding choice for biomedical applications. Although there are many different types of silk in nature,Bombyx mori(B. mori) silk accounts for about 90% of global production and is the most thoroughly investigated and the most commonly used. Silk fibroin (SF) and silk sericin (SS) are the two main protein constituents of silk. SF has been manufactured in various morphologic forms (e.g. hydrogels, sponges, films, etc) and has been widely used in the biomedical field, especially as a scaffold in tissue engineering. Similarly, SS has demonstrated a vast potential as a suitable biomaterial in tissue engineering and regenerative medicine. Initial studies on SF and SS as wound dressings have shown encouraging results. This review aims to comprehensively discuss the potential role of silk proteins in refining wound healing and skin regeneration.

Synergetic Effects of Sericin and Turmeric on Burn Wound Healing in Mice

Burn wounds are one of the most hazardous issues, globally. Silkworm produces a protein called sericin. Sericin assists in wound healing by facilitating the proliferation of keratinocytes and fibroblasts, while turmeric is potentially helpful in wound healing because of its antioxidant, anti-inflammatory, and anti-infectious activities. The current study aimed to investigate the synergetic and individual effects of turmeric, sericin, and their nanoparticles on burn wounds in mice. The female mice having age of 2 months (each weighing 29-30 g) were arbitrarily distributed in 7 groups. Five mice were added to each group. Burn wounds were induced in mice by using a hot metal rod. Burn wounds were evaluated histologically and morphologically. Turmeric nanoparticles substantially improved the wound contraction area as compared to the negative control group and other treatment groups. The serum level of glutathione (4.9 ± 0.1 µmol/L), catalase (6.0 ± 0.2 mmol/mL), glutathione peroxidase (183.4 ± 5.1 U/L), and superoxide dismutase (194.6 ± 5.1 U/mL) was significantly increased in the turmeric nanoparticles (TNPs) group as compared to the negative control (2.8 ± 0.1 µmol/L, 3.5 ± 0.1 mmol/mL, 87.8 ± 3.0 U/L, and 92.0 ± 4.8 U/mL respectively). The minimum levels of malondialdehyde (3.8 ± 0.2 mmol/L) were noticed in the TNPs group contrary to the negative control (7.4 ± 0.2 mmol/L). The restoration of the epidermis was also observed to be faster in the TNPs group as compared to all other treatment groups. The histopathological analysis also demonstrated the effectiveness of turmeric, sericin, and their nanoparticles. In conclusion, turmeric, sericin, and their nanoparticles are effective in improving the healing process of burn wounds, but TNPs showed the most effective results as compared to all other treatment groups.

Silk Sericin and Its Effect on Skin Wound Healing: A State of the Art

Despite the significant progress in wound healing, chronic skin wounds remain a challenge for today's medicine. Due to the growing popularity of natural materials, silk protein-based dressings are gaining more attention in this field. Most studies refer to silk fibroin because sericin has been considered a waste product for years. However, sericin is also worth noting. Sericin-based dressings are mainly studied in cell cultures or animals. Sericin is the dressings' main component or can be included in more complex, advanced biomaterials. Recent studies highlight sericin's important role, noting its biocompatibility, biodegradability, and beneficial effects in skin wound healing, such as antibacterial activity, antioxidant and anti-inflammatory effects, or angiogenic properties. Developing sericin-based biomaterials is often simple, free of toxic by-products, and inexpensive, requiring no highly sophisticated apparatus. As a result, sericin-based dressings can be widely used in wound healing and have low environmental impact. However, the literature in this area is further limited. The following review collects and describes recent studies showing silk sericin's influence on skin wound healing.

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.

Exploring the mechanistic role of silk sericin biological and chemical conjugates for effective acute and chronic wound repair and related complications

OBJECTIVE

The current review is designed to elaborate and reveal the underlying mechanism of sericin and its conjugates of drug delivery during wounds and wound-related issues.

SIGNIFICANCE

Wound healing is a combination of different humoral, molecular, and cellular mechanisms. Various natural products exhibit potential in wound healing but among them, sericin, catches much attention of researchers due to its bio-functional properties such as being biodegradable, biocompatible, anti-oxidant, anti-bacterial, photo-protector, anti-inflammatory and moisturizing agent.

METHODS AND RESULTS

Sericin triggers the activity of anti-inflammatory cytokines which decrease cell adhesion and promote epithelial cell formation. Moreover, sericin enhances the anti-oxidant enzymes in the wounded area which scavenge the toxic consequences of reactive species (ROS).

CONCLUSIONS

This article highlights the mechanisms of how topical administration of sericin formulations along with 4-hexylresorcinol,\Chitosan\Ag@MOF-GO, polyvinyl alcohol (PVA), platelet lysate and UV photo cross-linked hydrogel sericin methacrylate which recruits a large number of cytokines on wounded area that stimulate fibroblasts and keratinocyte production as well as collagen deposition that led to early wound contraction. It also reviews the different sericin-based nanoparticles that play a significant role in rapid wound healing.

Polymeric scaffold integrated with nanovesicle-entrapped curcuminoids for enhanced therapeutic efficacy

Aim: Polymeric scaffolds were developed fortified with nanovesicle-encapsulated individual curcumin (CUR) and tetrahydrocurcumin (THC) for improved therapeutic efficacy due to their low stability and efficacy in native form. Method: Nanovesicle-encapsulated individual CUR and THC were fabricated using thin-film hydration techniques and characterized. Results & conclusion: CUR/THC in native and vesicle-encapsulated form demonstrated diminished LPS-instigate nitric oxide (NO) levels in macrophage cells in a concentration-dependent demeanor. However, vesicle-encapsulated CUR/THC inhibited NO production at lower concentrations, compared with the native CUR/THC form. Furthermore, the scaffold fortified with vesicle-encapsulated CUR/THC demonstrated improved physical properties with excellent antioxidant, biocompatibility, and human keratinocyte cell proliferation ability. The results recommended that nanovesicle-encapsulated THC can be retained as a potential substitute for CUR with improved therapeutic efficacy.

Sericin promotes chondrogenic proliferation and differentiation via glycolysis and Smad2/3 TGF-β signaling inductions and alleviates inflammation in three-dimensional models

Knee osteoarthritis is a chronic joint disease mainly characterized by cartilage degeneration. The treatment is challenging due to the lack of blood vessels and nerve supplies in cartilaginous tissue, causing a prominent limitation of regenerative capacity. Hence, we investigated the cellular promotional and anti-inflammatory effects of sericin, Bombyx mori-derived protein, on three-dimensional chondrogenic ATDC5 cell models. The results revealed that a high concentration of sericin promoted chondrogenic proliferation and differentiation and enhanced matrix production through the increment of glycosaminoglycans, COL2A1, COL X, and ALP expressions. SOX-9 and COL2A1 gene expressions were notably elevated in sericin treatment. The proteomic analysis demonstrated the upregulation of phosphoglycerate mutase 1 and triosephosphate isomerase, a glycolytic enzyme member, reflecting the proliferative enhancement of sericin. The differentiation capacity of sericin was indicated by the increased expressions of procollagen12a1, collagen10a1, rab1A, periostin, galectin-1, and collagen6a3 proteins. Sericin influenced the differentiation capacity via the TGF-β signaling pathway by upregulating Smad2 and Smad3 while downregulating Smad1, BMP2, and BMP4. Importantly, sericin exhibited an anti-inflammatory effect by reducing IL-1β, TNF-α, and MMP-1 expressions and accelerating COL2A1 production in the early inflammatory stage. In conclusion, sericin demonstrates potential in promoting chondrogenic proliferation and differentiation, enhancing cartilaginous matrix synthesis through glycolysis and TGF-β signaling pathways, and exhibiting anti-inflammatory properties.

Biological scaffold as potential platforms for stem cells: Current development and applications in wound healing

Wound repair is a complex challenge for both clinical practitioners and researchers. Conventional approaches for wound repair have several limitations. Stem cell-based therapy has emerged as a novel strategy to address this issue, exhibiting significant potential for enhancing wound healing rates, improving wound quality, and promoting skin regeneration. However, the use of stem cells in skin regeneration presents several challenges. Recently, stem cells and biomaterials have been identified as crucial components of the wound-healing process. Combination therapy involving the development of biocompatible scaffolds, accompanying cells, multiple biological factors, and structures resembling the natural extracellular matrix (ECM) has gained considerable attention. Biological scaffolds encompass a range of biomaterials that serve as platforms for seeding stem cells, providing them with an environment conducive to growth, similar to that of the ECM. These scaffolds facilitate the delivery and application of stem cells for tissue regeneration and wound healing. This article provides a comprehensive review of the current developments and applications of biological scaffolds for stem cells in wound healing, emphasizing their capacity to facilitate stem cell adhesion, proliferation, differentiation, and paracrine functions. Additionally, we identify the pivotal characteristics of the scaffolds that contribute to enhanced cellular activity.

Transcriptomic screening of novel targets of sericin in human hepatocellular carcinoma cells

Sericin, a natural protein derived from Bombyx mori, is known to ameliorate liver tissue damage; however, its molecular mechanism remains unclear. Herein, we aimed to identify the possible novel targets of sericin in hepatocytes and related cellular pathways. RNA sequencing analysis indicated that a low dose of sericin resulted in 18 differentially expressed genes (DEGs) being upregulated and 68 DEGs being downregulated, while 61 DEGs were upregulated and 265 DEGs were downregulated in response to a high dose of sericin (FDR ≤ 0.05, fold change > 1.50). Functional analysis revealed that a low dose of sericin regulated pathways associated with the complement and coagulation cascade, metallothionine, and histone demethylate (HDMs), whereas a high dose of sericin was associated with pathways involved in lipid metabolism, mitogen-activated protein kinase (MAPK) signaling and autophagy. The gene network analysis highlighted twelve genes, A2M, SERPINA5, MT2A, MT1G, MT1E, ARID5B, POU2F1, APOB, TRAF6, HSPA8, FGFR1, and OGT, as novel targets of sericin. Network analysis of transcription factor activity revealed that sericin affects NFE2L2, TFAP2C, STAT1, GATA3, CREB1 and CEBPA. Additionally, the protective effects of sericin depended on the counterregulation of APOB, POU2F1, OGT, TRAF6, and HSPA5. These findings suggest that sericin exerts hepatoprotective effects through diverse pathways at different doses, providing novel potential targets for the treatment of liver diseases.

Poly (vinyl alcohol)-gelatin-sericin copolymerized film fortified with vesicle-entrapped demethoxycurcumin/bisdemethoxycurcumin for improved stability, antibacterial, anti-inflammatory, and skin tissue regeneration

Vesicle delivery carriers, used to stabilize hydrophobic drugs, are characterized by the propensity to aggregate, and fuse, limiting its applications. Fortifying vesicle-entrapped drugs within a biodegradable polymeric film constitutes a promising solution. In this study, biodegradable poly (vinyl alcohol) copolymerized with gelatin-sericin film and integrated alongside vesicle-entrapped demethoxycurcumin (DMC) or bisdemethoxycurcumin (BDMC) was developed, extensively characterized for improve efficacy, and compared. Vesicle-entrapped DMC or BDMC was spherical in shape with no changes in size, zeta-potential, and morphology after storing at 4 °C for 30 days. Antibacterial activity of vesicle-entrapped DMC formulations against Acinetobacter baumannii and Staphylococcus epidermidis was more effective than that of its free form. DMC and BDMC demonstrated dose dependent reduction in lipopolysaccharides (LPS)-induced nitric oxide (NO) levels either in free or in entrapped form. Moreover, vesicle-entrapped DMC/BDMC suppressed NO production at lower concentrations, compared with that of their free form and significantly improved the viability of RAW264.7 and HaCaT cells. Furthermore, functionalized film with vesicle-entrapped DMC/BDMC demonstrated excellent radical scavenging, biocompatibility, and cell migration efficacy. Thus, incorporating vesicle, entrapped DMC/BDMC within biodegradable polymeric film may comprised a promising strategy for improving stability, wound healing, and inflammation attenuation efficacy.

Natural agents as wound-healing promoters

The management of acute and chronic wounds resulting from diverse injuries poses a significant challenge to clinical practices and healthcare providers. Wound healing is a complex biological process driven by a natural physiological response. This process involves four distinct phases, namely hemostasis, inflammation, proliferation, and remodeling. Despite numerous investigations on wound healing and wound dressing materials, complications still persist, necessitating more efficacious therapies. Wound-healing materials can be categorized into natural and synthetic groups. The current study aims to provide a comprehensive review of highly active natural animal and herbal agents as wound-healing promoters. To this end, we present an overview of in vitro, in vivo, and clinical studies that led to the discovery of potential therapeutic agents for wound healing. We further elucidated the effects of natural materials on various pharmacological pathways of wound healing. The results of previous investigations suggest that natural agents hold great promise as viable and accessible products for the treatment of diverse wound types.

Exploring the apoptotic effects of sericin on HCT116 cells through comprehensive nanostring transcriptomics and proteomics analysis

Sericin, a silk protein from Bombyx mori (silkworms), has many applications, including cosmetics, anti-inflammation, and anti-cancer. Sericin complexes with nanoparticles have shown promise for breast cancer cell lines. Apoptosis, a programmed cell death mechanism, stops cancer cell growth. This study found that Sericin urea extract significantly affected HCT116 cell viability (IC50 = 42.00 ± 0.002 µg/mL) and caused apoptosis in over 80% of treated cells. S-FTIR analysis showed significant changes in Sericin-treated cells' macromolecule composition, particularly in the lipid and nucleic acid areas, indicating major cellular modifications. A transcriptomics study found upregulation of the apoptotic signaling genes FASLG, TNFSF10, CASP3, CASP7, CASP8, and CASP10. Early apoptotic proteins also showed that BAD, AKT, CASP9, p53, and CASP8 were significantly upregulated. A proteomics study illuminated Sericin-treated cells' altered protein patterns. Our results show that Sericin activated the extrinsic apoptosis pathway via the caspase cascade (CASP8/10 and CASP3/7) and the death receptor pathway, involving TNFSF10 or FASLG, in HCT116 cells. Upregulation of p53 increases CASP8, which activates CASP3 and causes HCT116 cell death. This multi-omics study illuminates the molecular mechanisms of Sericin-induced apoptosis, sheds light on its potential cancer treatment applications, and helps us understand the complex relationship between silk-derived proteins and cellular processes.

Advances of regenerated and functionalized silk biomaterials and application in skin wound healing

The cocoon silk of silkworms (Bombyx mori) has multiple potential applications in biomedicine due to its good biocompatibility, mechanical properties, degradability, and plasticity. Numerous studies have confirmed that silk material dressings are more effective than traditional ones in the skin wound healing process. Silk material research has recently moved toward functionalized biomaterials and achieved remarkable results. Herein, we summarize the recent advances in functionalized silk materials and their efficacy in skin wound healing. In particular, transgenic technology has realized the specific expression of human growth factors in the silk glands of the silkworms, which lays the foundation for fabricating novel and low-cost functionalized materials. Without a green and safe preparation process, the best raw silk materials cannot be made into medically safe products. Therefore, we provide an overview of green and gentle approaches for silk degumming and silk sericin (SS) extraction. Moreover, we summarize and discuss the processing methods of silk fibroin (SF) and SS materials and their potential applications, such as burns, diabetic wounds, and other wounds. This review aims to enhance our understanding of new advances and directions in silk materials and guide future biomedical research.

Silk protein sericin: a promising therapy for Achilles tendinopathy-evidence from an experimental rat model

OBJECTIVE

This study investigated the efficacy of sericin in treating experimental Achilles tendinopathy (AT) in rats via the transforming growth factor-beta (TGF-β)/mothers against decapentaplegic (Smad) pathway compared with diclofenac sodium (DS).

METHOD

An AT model was induced in rats using collagenase enzyme type I and divided into 5 groups: C (control), AT (diseased control), ATS (AT treated with sericin), ATN (AT treated with DS), and ATSN (AT treated with sericin and DS). Sericin injection was given on the 3rd and 6th days by intratendinous injection (0.8 g/kg/mL), and DS was administered for 14 days by oral gavage (1.1 mg/kg/day). Serum concentrations of total oxidant-antioxidant status (TOS-TAS), TGF-β1, decorin, Smad2, and connective tissue growth factor (CTGF) were measured. Histopathologic and immunohistochemical (IHC) studies were conducted on Achilles tendon samples.

RESULTS

The TOS, oxidative stress index (OSI), TGF-β1, Smad2, CTGF, and decorin serum concentrations were significantly higher in AT than in C and significantly lower in ATS than in AT (P<0.05). Histopathological examination revealed that irregular fibers, degeneration, and round cell nuclei were significantly elevated in AT. Spindle-shaped fibers were similar to those in C, and degeneration was reduced in ATS. TGF-β1 and Smad2/3 expression was increased, and collagen type I alpha-1 (Col1A1) expression was decreased in AT vs. C (P=0.001). In the ATS, TGF-β1 and Smad2/3 expression decreased, and Col1A1 expression increased. The Bonar score significantly increased in the AT group (P =0.001) and significantly decreased in the ATS group (P =0.027).

CONCLUSION

Sericin shows potential efficacy in reducing oxidative stress and modulating the TGF-β/Smad pathway in experimental AT models in rats. It may be a promising therapeutic agent for AT, warranting further clinical studies for validation. Key Points • This study revealed that sericin mitigates AT-induced damage through the TGF-β/Smad pathway in an AT rat model. • ELISA and IHC investigations corroborated the effectiveness of sericin via the pivotal TGF-β/Smad pathway in tissue repair. • Evidence indicates that sericin enhances collagen synthesis,shapes tendon fiber structure, and diminishes histopathological degeneration. • Sericin's antioxidant properties were reaffirmed in its AT treatment application.

Fabrication, Structural Characteristics, and Properties of Sericin-Coated Wool Nonwoven Fabrics

Recently, nonwoven fabrics from natural silk have attracted considerable attention for biomedical and cosmetic applications because of their good mechanical properties and cytocompatibility. Although these fabrics can be easily fabricated using the binding character of sericin, the high cost of silk material may restrict its industrial use in certain areas. In this study, sericin was added as a binder to a cheaper material (wool) to prepare wool-based nonwoven fabrics and investigate the effect of the amount of sericin added on the structural characteristics and properties of the wool nonwoven fabric. It was found using SEM that sericin coated the surface of wool fibers and filled the space between them. With an increase in sericin addition, the porosity, moisture regain, and the contact angle of the sericin-coated wool nonwoven fabric decreased. The maximum stress and initial Young's modulus of the nonwoven fabric increased with the increase in sericin amount up to 32.5%, and decreased with a further increase in the amount of sericin. Elongation at the end steadily decreased with the increase in sericin addition. All of the nonwoven fabrics showed good cytocompatibility, which increased with the amount of sericin added. These results indicate that sericin-coated wool-based nonwoven fabrics may be successfully prepared by adding sericin to wool fibers, and that the properties of these fabrics may be diversely controlled by altering the amount of sericin added, making them promising candidates for biomedical and cosmetic applications.

Structural Characteristics and Properties of Redissolved Silk Sericin

Silk sericin has garnered the attention of researchers as a promising biomaterial because of its good biocompatibility and high water retention. However, despite its useful properties, the poor storage stability of sericin has restricted its extensive use in biorelated applications. This study extracted sericin from silkworm cocoon, dried and stored it as a solid, and then dissolved it in hot water conditions to improve the storage stability of sericin for its use. The dissolution behavior of the extracted sericin solids was examined in conjunction with the structural characteristics and properties of dissolved sericin. Consequently, the results of solution viscosity, gel strength, crystallinity index, and thermal decomposition temperature indicated that the molecular weight (MW) of the dissolved sericin remained constant until a dissolution time of 5 min, following which deterioration was observed. The optimum condition of dissolution of the extracted sericin solid was 5 min at 90 °C. Conclusively, the extracted sericin could be stored in a dry state and dissolved to prepare redissolved sericin aqueous solution with the same MW as extracted sericin, thereby improving the storage stability of the sericin aqueous solution.

Regulatory effect of sericin protein in inflammatory pathways; A comprehensive review

Sericin protein is a type of protein derived from silk cocoons. Sericin hydrogen bonds cause adhesion to the silk cocoon. This substance contains a large amount of serine amino acids in its structure. At first, the medicinal properties of this substance were unknown, but today many properties have been discovered for this substance. The unique properties of this substance have made it widely used in the pharmaceutical and cosmetic industries. The applications of Sericin in pharmacy are as follows. Sericin is used to repair wounds by producing collagen. Other uses for the drug include anti-diabetic, anti-cholesterol, metabolic modulator, anti-tumor, heart protection, antioxidant, antibacterial, wound healing, cell proliferation, UV protection, freezing, and skin moisturizing. The physicochemical properties of Sericin have attracted the attention of pharmacists and their widespread use in the production of drugs and treatment of diseases. One of the critical and unique properties of Sericin is its anti-inflammatory property. In this article, this property of Sericin is discussed in detail, and according to the experiments performed by pharmacists, this substance has shown a significant effect in eliminating inflammation. This study aimed to evaluate the impact of Sericin protein in relieving inflammation.

Effects of sericin and egg white on the inflammation of damaged skin in mice

Sericin and egg white (EW) have shown the ability to promote wound healing. However, there have been insufficient studies regarding the effects of sericin and EW mixtures on wound healing. This study aimed to investigate the effects of a hybrid sericin and EW solution on wound repair and inflammation-related indicators in mouse skin. In this work, sericin with a low molecular weight was first mixed with homogeneous EW to prepare a hybrid wound dressing. Histology evaluation, the expression of C-reactive protein (CRP) and inflammatory cytokines in mice were tested to determine the effects of this dressing on skin injuries in mice. The results showed that sericin and the hybrid solution of sericin and EW effectively promoted wound healing in mouse skin. The wound recovery rates of mice 12 days after treatment with a medium dose of sericin (0.2 g ml^-1) and the same dosage of sericin with added EW were 1.32 and 1.65 times that of mice treated with phosphate buffer saline as a control, respectively. In addition, the mixture solution was more effective in wound healing than sericin alone. Sericin with EW significantly reduced the expression of CRP and inflammatory cytokines in mice during wound healing. A sericin and EW hybrid solution can effectively shorten the time needed for wound healing and reduce inflammation-related indicators in mice, making it a promising candidate for wound dressing.

Evaluation of the effects of three natural products and a hemostatic agent on wound healing: an experimental study

BACKGROUND

People have used many natural materials such as plant leaves, roots, liquids derived from plants, and animal products to treat wounds throughout history. It can be said that the research on wound care in recent years have focused on traditional and natural products again. This study aimed to investigate the effects of sweetgum oil, propolis, silk protein, and Ankaferd Blood Stopper (ABS) on wound healing in an experimental excisional wound model.

METHODS

: Including 36 Balb/c inbreed mice in the study were divided equally into four groups. Two circular excisional wounds were created on the dorsal skin of mice under anesthesia using a punch biopsy device. The wounds of the first group of mice were topically dressed with sweetgum oil, the second group mice with propolis, the third group mice with silk protein, and the fourth group mice with ABS daily. Tissue samples were taken from the wounds of mice on the 7th and 14th day of wound formation, and histological examinations were performed. On the 14th day, the wounds created in all mice were healed, and the experiment was terminated.

RESULTS

Mice in the silk protein group had faster wound healing. There was no statistical difference between the groups in immunohistochemical examinations. In the ABS group, the findings of the inflammatory process were more prominent.

DISCUSSION

In conclusions, propolis, sweetgum oil, silk protein, and ABS positively affect different parameters in wound healing and support wound healing.

Efficacy of Silk Sericin and Jasminum grandiflorum L. Leaf Extract on Skin Injuries Induced by Burn in Mice

Burns wounds are one of the most health-threatening problems worldwide. Sericin is a natural protein synthesized by the silkworm Bombyx mori L. It is a natural biomaterial that helps in the management of wounds by promoting the proliferation of fibroblasts and keratinocytes. Jasminum grandiflorum L leaves contain high mucilage content and have been used to cure various dermal wounds in ancient times. The present study was aimed to investigate the individual and synergetic effect of sericin and J. grandiflorum leaves extract on burn injury in mice. Ten-week-old mice weighing 22 g ± 5 g were randomly divided into eight groups, each group containing 10 mice. Burn injury in mice was induced by using a hot metal rod. Wounds were evaluated morphologically and histologically. In comparison with controls, 4% sericin + jasmine (S + J) expressively improved wound contraction area. Restoration of the epidermis was also faster in S + J 4% group (P ≤ .01) than in other groups. Histopathological analysis also verified the efficacy of the 4% S + J cream. It is concluded that a mixture of sericin and jasmine leaves effectively improved the healing process of skin burns.

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.

Sericin-mediated improvement of dysmorphic cardiac mitochondria from hypercholesterolaemia is associated with maintaining mitochondrial dynamics, energy production, and mitochondrial structure

CONTEXT

Sericin is a component protein in the silkworm cocoon [Bombyx mori Linnaeus (Bombycidae)] that improves dysmorphic cardiac mitochondria under hypercholesterolemic conditions. This is the first study to explore cardiac mitochondrial proteins associated with sericin treatment.

OBJECTIVE

To investigate the mechanism of action of sericin in cardiac mitochondria under hypercholesterolaemia.

MATERIALS AND METHODS

Hypercholesterolaemia was induced in Wistar rats by feeding them 6% cholesterol-containing chow for 6 weeks. The hypercholesterolemic rats were separated into 2 groups (n = 6 for each): the sericin-treated (1,000 mg/kg daily) and nontreated groups. The treatment conditions were maintained for 4 weeks prior to cardiac mitochondria isolation. The mitochondrial structure was evaluated by immunolabeling electron microscopy, and differential mitochondrial protein expression was determined and quantitated by two-dimensional gel electrophoresis coupled with mass spectrometry.

RESULTS

A 32.22 ± 2.9% increase in the percent striated area of cardiac muscle was observed in sericin-treated hypercholesterolemic rats compared to the nontreatment group (4.18 ± 1.11%). Alterations in mitochondrial proteins, including upregulation of optic atrophy 1 (OPA1) and reduction of NADH-ubiquinone oxidoreductase 75 kDa subunit (NDUFS1) expression, are correlated with a reduction in mitochondrial apoptosis under sericin treatment. Differential proteomic observation also revealed that sericin may improve mitochondrial energy production by upregulating acetyl-CoA acetyltransferase (ACAT1) and NADH dehydrogenase 1α subcomplex subunit 10 (NDUFA10) expression.

DISCUSSION AND CONCLUSIONS

Sericin treatment could improve the dysmorphic mitochondrial structure, metabolism, and energy production of cardiac mitochondria under hypercholesterolaemia. These results suggest that sericin may be an alternative treatment molecule that is related to cardiac mitochondrial abnormalities.

Silk Sericin: A Promising Sustainable Biomaterial for Biomedical and Pharmaceutical Applications

Silk is a natural composite fiber composed mainly of hydrophobic fibroin and hydrophilic sericin, produced by the silkworm Bombyx mori. In the textile industry, the cocoons of B. mori are processed into silk fabric, where the sericin is substantially removed and usually discarded in wastewater. This wastewater pollutes the environment and water sources. However, sericin has been recognized as a potential biomaterial due to its biocompatibility, immunocompatibility, biodegradability, anti-inflammatory, antibacterial, antioxidant and photoprotective properties. Moreover, sericin can produce hydrogels, films, sponges, foams, dressings, particles, fibers, etc., for various biomedical and pharmaceutical applications (e.g., tissue engineering, wound healing, drug delivery, cosmetics). Given the severe environmental pollution caused by the disposal of sericin and its beneficial properties, there has been growing interest in upcycling this biomaterial, which could have a strong and positive economic, social and environmental impact.

Novel Amoxicillin-Loaded Sericin Biopolymeric Nanoparticles: Synthesis, Optimization, Antibacterial and Wound Healing Activities

Infected wounds are a major threat among diabetic patients. Technological advancements are currently increasing the number of new adjunctive therapies that may be potent agents for speeding recovery, lowering the amputation rate and limiting infection recurrences. A novel formula with promising antibacterial activity, namely sericin/propolis/Amoxicillin nanoparticles, was assessed as a potent treatment of infected wounds in normal and diabetic rats. Skin wound healing efficiency was assessed through wound healing scorings, bacterial load assessment and histological examinations. It was revealed that upon using sericin/propolis/Amoxicillin nanoparticles, complete wound healing was successfully achieved after 10 and 15 days postinjury for nondiabetic and diabetic rats, respectively. However, the bacterial load in the induced infected wounds was extremely low (0-10 CFU/mL) after 15 days post-treatment. The histological studies revealed that the dermis was more organized with new matrix deposition, and mature collagen fibers were observed among the treated animal groups. The present study is the first preclinical study which reported the importance of silk sericin in the form of nano-sericin/propolis loaded with Amoxicillin as an effective treatment against bacterial wound infections.

Using polyvinyl alcohol-ionic hydrogels containing a wound healing agent to manage wounds in different environments

OBJECTIVE

To explore the effects of pH on properties of polyvinyl alcohol (PVA)-ionic hydrogels containing wound healing promoters.

METHOD

PVA was combined with a natural wound healing promoter (silk sericin (SS)), and an anionic agent (eosin (ES)) or cationic agent (methylene blue (MB)), and made into hydrogels. Properties of the hydrogels and behaviour at different pHs were investigated.

RESULTS

The density and gel fraction of PVA/SS-ES hydrogel and PVA/SS-MB hydrogel were considerably lower compared with hydrogel without SS. The swelling ratio and degradation of the hydrogels increased with increasing SS concentration in all pH solutions. The influence of SS in interrupting long-chain PVA molecules was confirmed based on changes in Fourier-transform infrared spectroscopy (FTIR). The SS released from the gels was found to interact with the ionic agent and influenced the release profile of the ionic agent. Surprisingly, the anionic agent in PVA/SS-ES hydrogel showed 70% release in high pH solution whereas the cationic agent in PVA/SS-MB hydrogel showed 86% release in low pH solution. Moreover, the active agent could accumulate on the skin layer and had a positive effect on a specific wound area.

CONCLUSION

Based on the results obtained in this study, it is suggested to use anionic hydrogels containing wound healing promoter for wounds at high pH and cationic hydrogels containing wound healing promoter for wounds with low pH. Ability to improve wound healing using a natural healing agent combined with ionic agents and controlling the pH of hydrogels will help in developing quick and low-cost treatment for wounds.

Silk sericin-based materials for biomedical applications

Silk sericin, a natural protein extracted from silkworm cocoons, has been extensively studied and utilized in the biomedical field because of its superior biological activities and controllable chemical-physical properties. Sericin is biocompatible and naturally cell adhesive, enabling cell attachment, proliferation, and differentiation in sericin-based materials. Moreover, its abundant functional groups from variable amino acids composition allow sericin to be chemically modified and cross-linked to form versatile constructs serving as alternative matrixes for biomedical applications. Recently, sericin has been constructed into various types of biomaterials for tissue engineering and regenerative medicine, including various bulk constructions (films, hydrogels, scaffolds, conduits, and devices) and micro-nano formulations. In this review, we systemically summarize the properties of silk sericin, introduce its different forms, and demonstrate their newly-developed as well as potential biomedical applications.

Wound dressing adherence: a review

Wound dressing adherence is an important problem that is frequently encountered in wound care, and is associated with both clinical and economic burdens. However, only a few review articles have focused on this issue. The objective of this review was to present a comprehensive discussion of wound dressing adherence, including the mechanism of dressing adherence, adverse consequences (clinical burdens and economic burdens), factors affecting adherence (dressing-, patient- and wound-related factors, and factors related to the wound care procedure), tests to assess dressing adherence (in vitro assay, in vivo assay and clinical trials), and reduction of wound adherence (modification of dressing adherence and special care in particular patients). Accordingly, this review article emphasises an awareness of dressing adherence, and is intended to be an informative source for the development of new dressings and for wound management.

Genetically engineered FGF1-sericin hydrogel material treats intrauterine adhesion and restores fertility in rat

Endometrial injury can cause intrauterine adhesions (IUA) and induce the formation of endometrial fibrosis, leading to infertility and miscarriage. At present, there is no effective treatment method for severe IUA and uterine basal injury with adhesion area larger than 1/3 of the uterus. In this study, we prepared FGF1 silk sericin hydrogel material (FGF1-SS hydrogel) to treat endometrial injury and prevent endometrial fibrosis. Compared with the silk sericin hydrogel material (WT-SS hydrogel), FGF1-SS hydrogel significantly promotes the cell migration and infiltration ability of endometrial stromal cells (ESCs). More importantly, FGF1-SS hydrogel can release FGF1 stably for a long time and inhibit The ESCs injury model forms fibrosis through the TGF-β/Smad pathway. In the IUA rat model, FGF1-SS hydrogel treatment effectively restored the number of uterine glands and uterine wall thickness in rats, with a fertility rate of 65.1 ± 6.4%. The results show that FGF1-SS hydrogel is expected to be a candidate to prevent IUA.

Bioprinting Au Natural: The Biologics of Bioinks

The development of appropriate bioinks is a complex task, dependent on the mechanical and biochemical requirements of the final construct and the type of printer used for fabrication. The two most common tissue printers are micro-extrusion and digital light projection printers. Here we briefly discuss the required characteristics of a bioink for each of these printing processes. However, physical printing is only a short window in the lifespan of a printed construct-the system must support and facilitate cellular development after it is printed. To that end, we provide a broad overview of some of the biological molecules currently used as bioinks. Each molecule has advantages for specific tissues/cells, and potential disadvantages are discussed, along with examples of their current use in the field. Notably, it is stressed that active researchers are trending towards the use of composite bioinks. Utilizing the strengths from multiple materials is highlighted as a key component of bioink development.

Systemic and Local Silk-Based Drug Delivery Systems for Cancer Therapy

For years, surgery, radiotherapy, and chemotherapy have been the gold standards to treat cancer, although continuing research has sought a more effective approach. While advances can be seen in the development of anticancer drugs, the tools that can improve their delivery remain a challenge. As anticancer drugs can affect the entire body, the control of their distribution is desirable to prevent systemic toxicity. The application of a suitable drug delivery platform may resolve this problem. Among other materials, silks offer many advantageous properties, including biodegradability, biocompatibility, and the possibility of obtaining a variety of morphological structures. These characteristics allow the exploration of silk for biomedical applications and as a platform for drug delivery. We have reviewed silk structures that can be used for local and systemic drug delivery for use in cancer therapy. After a short description of the most studied silks, we discuss the advantages of using silk for drug delivery. The tables summarize the descriptions of silk structures for the local and systemic transport of anticancer drugs. The most popular techniques for silk particle preparation are presented. Further prospects for using silk as a drug carrier are considered. The application of various silk biomaterials can improve cancer treatment by the controllable delivery of chemotherapeutics, immunotherapeutics, photosensitizers, hormones, nucleotherapeutics, targeted therapeutics (e.g., kinase inhibitors), and inorganic nanoparticles, among others.

Nonmulberry silk proteins: multipurpose ingredient in bio-functional assembly

The emerging field of tissue engineering and regenerative medicines utilising artificial polymers is facing many problems. Despite having mechanical stability, non-toxicity and biodegradability, most of them lack cytocompatibility and biocompatibility. Natural polymers (such as collagen, hyaluronic acid, fibrin, fibroin, and others), including blends, are introduced to the field to solve some of the relevant issues. Another natural biopolymer: silkworm silk gained special attention primarily due to its specific biophysical, biochemical, and material properties, worldwide availability, and cost-effectiveness. Silk proteins, namely fibroin and sericin extracted from domesticated mulberry silkwormBombyx mori, are studied extensively in the last few decades for tissue engineering. Wild nonmulberry silkworm species, originated from India and other parts of the world, also produce silk proteins with variations in their nature and properties. Among the nonmulberry silkworm species,Antheraea mylitta(Indian Tropical Tasar),A. assamensis/A. assama(Indian Muga), andSamia ricini/Philosamia ricini(Indian Eri), along withA. pernyi(Chinese temperate Oak Tasar/Tussah) andA. yamamai(Japanese Oak Tasar) exhibit inherent tripeptide motifs of arginyl glycyl aspartic acid in their fibroin amino acid sequences, which support their candidacy as the potential biomaterials. Similarly, sericin isolated from such wild species delivers unique properties and is used as anti-apoptotic and growth-inducing factors in regenerative medicines. Other characteristics such as biodegradability, biocompatibility, and non-inflammatory nature make it suitable for tissue engineering and regenerative medicine based applications. A diverse range of matrices, including but not limited to nano-micro scale structures, nanofibres, thin films, hydrogels, and porous scaffolds, are prepared from the silk proteins (fibroins and sericins) for biomedical and tissue engineering research. This review aims to represent the progress made in medical and non-medical applications in the last couple of years and depict the present status of the investigations on Indian nonmulberry silk-based matrices as a particular reference due to its remarkable potentiality of regeneration of different types of tissues. It also discusses the future perspective in tissue engineering and regenerative medicines in the context of developing cutting-edge techniques such as 3D printing/bioprinting, microfluidics, organ-on-a-chip, and other electronics, optical and thermal property-based applications.

Comparison of Sericins from Different Sources as Natural Therapeutics against Ulcerative Colitis

Sericin has become a promising natural anti-inflammatory protein. However, the biological functions of sericins largely depend on their origins; no study has yet been carried out to comparatively investigate the therapeutic effects of sericins from different sources against inflammatory diseases. Herein, we extracted and purified three kinds of sericins, namely silkworm sericin (SS), tussah sericin (TS), and castor silk sericin (CSS). These sericins showed negligible cytotoxicities against colitis-associated cells (colon epitheliums and activated macrophages). Further investigations displayed that these sericins could remarkably downregulate the secreted amounts of TNF-α, promote the recovery of the damaged colonic epithelial barrier, and eliminate endogenous reactive oxygen species in Raw 264.7 macrophages and Caenorhabditis elegans. In vivo experiments demonstrated that chitosan/alginate hydrogel-encapsulating SS could achieve efficient accumulation of SS in the colitis tissues and thereby play a more effective role in relieving ulcerative colitis (UC) than TS and CSS. Our findings collectively demonstrate that SS can be extracted, formulated, and used as a robust therapeutic agent for the oral treatment of UC.

In Vitro Interaction of Doxorubicin-Loaded Silk Sericin Nanocarriers with MCF-7 Breast Cancer Cells Leads to DNA Damage

In this paper, Bombyx mori silk sericin nanocarriers with a very low size range were obtained by nanoprecipitation. Sericin nanoparticles were loaded with doxorubicin, and they were considered a promising tool for breast cancer therapy. The chemistry, structure, morphology, and size distribution of nanocarriers were investigated by Fourier transformed infrared spectroscopy (FTIR–ATR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and dynamic light scattering (DLS). Morphological investigation and DLS showed the formation of sericin nanoparticles in the 25–40 nm range. FTIR chemical characterization showed specific interactions of protein–doxorubicin–enzymes with a high influence on the drug delivery process and release behavior. The biological investigation via breast cancer cell line revealed a high activity of nanocarriers in cancer cells by inducing significant DNA damage.

A clinical comparison of pure knitted silk and a complex synthetic skin substitute for the treatment of partial thickness burns

Currently, many dressings are commercially available for the treatment of burn wounds. Some of these wound dressings remain on the wound, prevent painful dressing changes, and reduce tissue scarring. Nevertheless, still a wound dressing that is cost-effective, produces good wound healing properties, and has a high patient satisfaction is needed. Standard care of superficial burn wounds differs between burn centres. This study aimed to determine a dressing with easy appliance, accurate pain control, favourable outcome, and cost-effectiveness. Therefore, we compared the widely used but expensive Suprathel with the rather new but much cheaper Dressilk in the clinical setting. In a prospective clinical study, the healing of partial thickness burn wounds after simultaneous treatment with Suprathel and Dressilk was examined in 20 patients intra-individually. During wound healing, pain, infection, exudation, and bleeding were evaluated. A subjective scar evaluation was performed using the Patient and Observer Scar Scale. Both dressings were easy to apply, remained on the wound in place, and were gradually cut back as reepithelisation proceeded and showed similar times to wound closure. Dressing changes were not necessary, and neither infections nor bleeding was detected. Overall exudation and pain were highest in the beginning but declined during the wound-healing phase without significant differences. In the follow-up scar evaluation after 12 months, patients reported overall high satisfaction. Overall, the modern dressings Suprathel and Dressilk (solely made out of pure silk) led to safe wound healing without infection and rapidly reduced pain. There was no need for dressing changes, and they had similar clinical outcomes in scar evaluation. Therefore, both dressings seem to be ideal for the treatment of superficial burns. Because acquisition costs remain one of the main factors in the treatment of burns, Dressilk, which is ~20 times cheaper than Suprathel, remains a good option for the treatment of partial thickness burns.

The Fabrication of Poly(Σ-caprolactone)-Poly(ethylene oxide) Sandwich Type Nanofibers Containing Sericin-Capped Silver Nanoparticles as an Antibacterial Wound Dressing

In this study, antibacterial, synthetic poly(Σ-caprolactone)-poly(ethylene oxide) (PCL-PEO) multilayer nanofibers were produced by an electrospinning method. The material was synthesized in 3 layers. The upper-lower protective layers were produced by PCL nanofibers and the intermediate layer was produced from PEO nanofiber containing sericin-capped silver nanoparticles (S-AgNPs). The electrospinning conditions in which nano-sized, smooth, bead-free fibers were obtained was determined to be an applied voltage of 20 kV, a flow rate of 8 μL/min and a distance between the collector and the needle tip of 22 cm for the PCL layer (dissolved at a 12% g/mL concentration in a chloroform:methanol (3:2) solvent mixture) layer. For the S-AgNPs doped PEO layer (dissolved at a 3.5% g/mL concentration in water), the corresponding conditions were determined to be 20 kV, 15 μL/min and 20 cm. To characterize the three-layer material that consisted of PCL and S-AgNPs doped PEO layers, FTIR and SEM analyses were performed, and the water retention capacity, in situ degradability and antibacterial activity of the material was investigated. According to SEM analysis, the fibers obtained were found to be nano-sized, smooth and bead-free and the average size of the nanofibers forming the PCL layer was 687 nm while the average size of the fibers forming the PEO layer was 98 nm. Antibacterial activity tests were performed using gram-positive (Staphylococcus aureus ATCC 6538) and gram-negative (Escherichia coli ATCC 25922) bacteria and the resulting biomaterial was found to have antimicrobial effect on both gram-negative and gram-positive bacteria. It was determined that the 3-layer material obtained in this study can be used as a wound dressing.

Bioengineered ethosomes encapsulating AgNPs and Tasar silk sericin proteins for non melanoma skin carcinoma (NMSC) as an alternative therapeutics

Rising cases of Non melanoma skin carcinoma (NMSC) and escalating levels of ultraviolet radiations have underlined a profound correlation with the elevating levels of environmental detoriation and increasing health issues. However, the availability of therapeutics has not aided in controlling the recurrence rates of skin carcinoma. Frequent administration of therapeutics with higher chances of facial deformity escalates the patient's treatment expenses. Thus, this study initiates a low cost effective and biodegradable therapy by exploring four formulations with combinations of silver nanoparticles (AgNPs), sericin (isolated from cocoons of Antherea mylitta) and chitosan. Subsequently, various ethosomal formulations were evaluated as a platform for transdermal delivery vehicle for efficient skin intervention therapeutics. Characterization using UV visible spectroscopy, Dynamic light scattering, Fourier Infrared spectroscopy, X-ray dispersion, Transmission electron microscopy, Fluorescence assisted cell sorting and in vitro studies were done and it was inferenced that equal combination of AgNPs and sericin facilitated to combat the morphological and cellular deformation of the epidermoid A431skin carcinoma cells. The overproduction of superoxide (O^2.) and nitric oxide (NO) radicals consequently depolarized the mitochondrial membrane potential triggering apoptosis and necrosis. The in vivo experiments exhibited the stimulation of IgM secretion with T cell-mediated immune response. Therefore, this study proposes a novel approach for treatment of NMSC using biocompatible formulations delivered through ethosomes.

Protein composites from silkworm cocoons as versatile biomaterials

Silk is a naturally occurring biopolymer formed into fibers composed primarily of fibroin and sericin proteins. The outstanding mechanical properties of silk fibroin (SF) provides numerous applications for silk-based biomaterials. However, the canonical approaches for fabricating silk-based biomaterials typically involve degumming to remove the silk sericin (SS) to avoid adverse biological effects. Meanwhile, sericin has multiple biological functions including outstanding hydrophilicity, promoting cell attachment that are useful to exploit in new materials, inspiring the use of sericin-based biomaterials for biomedical applications. However, compared to fibroin, sericin is not a structural protein, thus sericin-based materials do not provide robust mechanical properties. To address this problem, we report an effective method for fabricating silk fibroin-sericin protein (SS-SF) composites directly from whole cocoons, negating the traditional extraction step to remove the sericin. This approach combines the material features from both fibroin as a structural unit and sericin as a biological functional unit, to achieve advantages regarding processing and materials properties, not only simplifying processing and maintaining the mechanical properties of the fibroin by avoiding degumming, but also endowing these SS-SF composite materials with enhanced hydrophilicity and cell adhesion performance to promote cell growth and proliferation. In addition, these protein composites could be fabricated into a variety of materials formats (e.g. films, sponges, monoliths) to fit different biomedical 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.

Biopolymeric, Nanopatterned, Fibrous Carriers for Wound Healing Applications

Background:

Any sort of wound injury leads to skin integrity and further leads to wound formation. Millions of deaths are reported every year, which contributes to an economical hamper world widely, this accounts for 10% of death rate that insight into various diseases.

Current Methodology:

Rapid wound healing plays an important role in effective health care. Wound healing is a multi-factorial physiological process, which helps in the growth of new tissue to render the body with the imperative barrier from the external environment. The complexity of this phenomenon makes it prone to several abnormalities. Wound healing, as a normal biological inherent process occurs in the body, which is reaped through four highly defined programmed phases, such as hemostasis, inflammation, proliferation, and remodeling and these phases occur in the proper progression. An overview, types, and classification of wounds along with the stages of wound healing and various factors affecting wound healing have been discussed systematically. Various biopolymers are reported for developing nanofibers and microfibers in wound healing, which can be used as a therapeutic drug delivery for wound healing applications. Biopolymers are relevant for biomedical purposes owing to biodegradability, biocompatibility, and non- toxicity. Biopolymers such as polysaccharides, proteins and various gums are used for wound healing applications. Patents and future perspectives have been given in the concluding part of the manuscript. Overall, applications of biopolymers in the development of fibers and their applications in wound healing are gaining interest in researchers to develop modified biopolymers and tunable delivery systems for effective management and care of different types of wounds.

Pharmaceutical applications of silk sericin

Silk sericin is an applicable protein extracted from dried silk cocoons, which are composed of a polar amino acid chain with hydroxyl, carboxyl, and amino functional groups. It anticipated that the functionality present in sericin provides excellent assets such as stability, release-modifying capacity, interaction with molecules, etc. It has various significant properties like biocompatibility, biodegradability, non-toxicity, hydrophilicity, etc. Besides, sericin exhibits the capability to form gels, nanoparticles, micro-particles, and keen bioengineered materials. Sericin also offers stability by strong affinity to the drug substance/molecules. Currently, sericin reconnoitered for a variety of pharmaceutical applications including solubility enhancement, release modifications, formulation stabilization, and as a drug carrier, etc. The focus of the review is to deliver an impression of the sericin based pharmaceutical applications including nanocrystal and nanoparticle stabilization, inhibition of devitrification, solubility enhancement, controlled and the extended-release formulation, targeted drug delivery, wound healing applications and as a suitable carrier.

Growth Factors Delivery System for Skin Regeneration: An Advanced Wound Dressing

Standard treatments of chronic skin ulcers based on the direct application of dressings still present several limits with regard to a complete tissue regeneration. Innovative strategies in tissue engineering offer materials that can tune cell behavior and promote growth tissue favoring cell recruitment in the early stages of wound healing. A combination of Alginate (Alg), Sericin (SS) with Platelet Lysate (PL), as a freeze-dried sponge, is proposed to generate a bioactive wound dressing to care skin lesions. Biomembranes at different composition were tested for the release of platelet growth factors, cytotoxicity, protective effects against oxidative stress and cell proliferation induction. The highest level of the growth factors release occurred within 48 h, an optimized time to burst a healing process in vivo; the presence of SS differently modulated the release of the factors by interaction with the proteins composing the biomembranes. Any cytotoxicity was registered, whereas a capability to protect cells against oxidative stress and induce proliferation was observed when PL was included in the biomembrane. In a mouse skin lesion model, the biomembranes with PL promoted the healing process, inducing an accelerated and more pronounced burst of inflammation, formation of granulation tissue and new collagen deposition, leading to a more rapid skin regeneration.

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.

Transgenic PDGF-BB/sericin hydrogel supports for cell proliferation and osteogenic differentiation

The present study demonstrates fabrication of PDGF-BB functionalized sericin hydrogel to explore biomaterials-related utility in bone tissue engineering.

Adipose-Derived Stem Cells (ADSCs) Loaded Gelatin-Sericin-Laminin Cryogels for Tissue Regeneration in Diabetic Wounds

Healing in wounds like pressure ulcers, diabetic ulcers, venous ulcers, and arterial insufficiency ulcers is immensely hampered and causes both an economic burden and morbidity to patients. These wounds face a plethora of hostile conditions like elevated reactive oxygen species (ROS), impaired angiogenesis, senescent fibroblasts, and deficient stem cells that significantly diminish the probability of self-healing in these wounds. Adipose-derived stem cell therapy (ADSC) presents a promising approach to achieve efficient healing in such cases. To address the complex scenario of chronic wounds, we propose a combinatorial approach of delivering ADSCs on antioxidant gelatin-sericin (GS) scaffolds coated with laminin (GSL), an endothelial basement protein to improve angiogenesis. The synthesized GS scaffolds showed values of compression modulus, pore size, porosity, and the swelling ratio in the range of 65 kPa, 158 ± 48.8 μm, 91.1% ± 1.25, and 28 ± 2.5, respectively. A DPPH assay revealed GS scaffolds exhibit around 20% more scavenging as against gelatin (G) scaffolds and better protection against free radical assault, thus enhancing cell viability and the metabolic index of fibroblast cells. Different cells, namely, fibroblasts, keratinocytes, and ADSCs, cultured on GS scaffolds had better metabolic activity as compared with G scaffolds. Laminin coating onto the scaffolds leads to improved attachment and tube formation of endothelial cells as depicted in scanning electron microscopy images. Finally, we validated the applicability of the ADSCs loaded laminin-coated GS scaffolds in a diabetic ulcer rat model. Hematoxylin and eosin, Masson's trichrome, and picrosirius red staining showed better regeneration and collagen remodeling in ADSCs loaded GSL scaffolds. Immunostaining of CD31 staining demonstrates enhanced angiogenesis in GSL-ADSC as compared with other groups.