Effects of Silk Sericin on Incision Wound Healing in a Dorsal Skin Flap Wound Healing Rat Model

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.

Chicoric acid inserted in protein Z cavity exhibits higher stability and better wound healing effect under oxidative stress

Oxidative stress is one of the limiting factors that inhibit wound healing. Phytochemicals especially chicoric acid have the potential to act as an antioxidant and scavenge reactive oxygen species, thereby promoting wound healing. However, most of the phytochemicals were easy to be degraded during storage or using due to the oxidative status in wound site. Herein, we introduce a high stable protein Z that can encapsulate chicoric acid during foaming. TEM results showed that the size of protein Z-chicoric acid is in the range of nanoscale (named PZ-CA nanocomposite), and protein Z encapsulation can significantly improve the stability of chicoric acid under oxidative stress. Moreover, PZ-CA nanocomposite exhibited favorable antioxidant properties, biocompatibility, and the ability to promote cell migration in vitro. The role of PZ-CA nanocomposite in skin regeneration was explored by a mice model. Results in vivo suggest that the PZ-CA nanocomposite promotes wound healing with a faster rate as compared with a commercial spray solution, mostly through attenuating the oxidative stress, promoting cell proliferation and collagen deposition. This work not only provides a delivery vector for bioactive molecules, but also develops a kind of nanocomposite with the property of promoting wound healing.

An Overview of Recent Developments in the Management of Burn Injuries

According to the World Health Organization (WHO), around 11 million people suffer from burns every year, and 180,000 die from them. A burn is a condition in which heat, chemical substances, an electrical current or other factors cause tissue damage. Burns mainly affect the skin, but can also affect deeper tissues such as bones or muscles. When burned, the skin loses its main functions, such as protection from the external environment, pathogens, evaporation and heat loss. Depending on the stage of the burn, the patient's condition and the cause of the burn, we need to choose the most appropriate treatment. Personalization and multidisciplinary collaboration are key to the successful management of burn patients. In this comprehensive review, we have collected and discussed the available treatment options, focusing on recent advances in topical treatments, wound cleansing, dressings, skin grafting, nutrition, pain and scar tissue management.

A comprehensive review of recent advances in silk sericin: Extraction approaches, structure, biochemical characterization, and biomedical applications

Silks are natural polymers that have been widely used for centuries. Silk consists of a filament core protein, termed fibroin, and a glue-like coating substance formed of sericin (SER) proteins. This protein is extracted from the silkworm cocoons (particularly Bombyx mori) and is mainly composed of amino acids like glycine, serine, aspartic acid, and threonine. Silk SER can be obtained using numerous methods, including enzymatic extraction, high-temperature, autoclaving, ethanol precipitation, cross-linking, and utilizing acidic, alkali, or neutral aqueous solutions. Given the versatility and outstanding properties of SER, it is widely fabricated to produce sponges, films, and hydrogels for further use in diverse biomedical applications. Hence, many authors reported that SER benefits cell proliferation, tissue engineering, and skin tissue restoration thanks to its moisturizing features, antioxidant and anti-inflammatory properties, and mitogenic effect on mammalian cells. Remarkably, SER is used in drug delivery depending on its chemical reactivity and pH-responsiveness. These unique features of SER enhance the bioactivity of drugs, facilitating the fabrication of biomedical materials at nano- and microscales, hydrogels, and conjugated molecules. This review thoroughly outlines the extraction techniques, biological properties, and respective biomedical applications of SER.

Characterization and Evaluation of Silk Sericin-Based Hydrogel: A Promising Biomaterial for Efficient Healing of Acute Wounds

The present study was aimed to prepare the potent silk sericin-based hydrogels in combination with plant extracts (curcumin and banana peel powder) and silver nanoparticles (AgNPs) to accelerate the acute wound healing process. Experimental excision wounds were created in mice by biopsy puncture, and the wound healing potential of silk sericin (2%)-based hydrogel and its combinations with curcumin (2%), banana peel powder (2%), and AgNPs (2%) was estimated by calculating the percent wound contraction, healing time, histology of skin tissues, and different biochemical tests. The results showed that the mice treated with sericin-based hydrogels showed significantly (P < 0.001) high percent wound contraction as compared to negative control, and wounds were healed in 11 days. The histological evaluation also showed that wounds covered with hydrogels were healed more than the uncovered wounds. Furthermore, the results of biochemical tests revealed that the treatment groups showed a significant (P < 0.001) decrease in the serum level of pro-inflammatory cytokines (IL-6). A significant (P < 0.001) increase in anti-inflammatory cytokines (IL-10) and anti-oxidant enzymes was observed in treatment groups. The highest wound healing potential was observed by sericin-based hydrogel containing banana peel powder, leaving behind the commercially available ointment polyfax (positive control). It can be concluded that the silk sericin-based hydrogels in combination with plant extract and AgNPs can be used as natural biomaterials in wound dressing for the rapid healing of acute wounds.

Engineered biomimetic micro/nano-materials for tissue regeneration

The incidence of tissue and organ damage caused by various diseases is increasing worldwide. Tissue engineering is a promising strategy of tackling this problem because of its potential to regenerate or replace damaged tissues and organs. The biochemical and biophysical cues of biomaterials can stimulate and induce biological activities such as cell adhesion, proliferation and differentiation, and ultimately achieve tissue repair and regeneration. Micro/nano materials are a special type of biomaterial that can mimic the microstructure of tissues on a microscopic scale due to its precise construction, further providing scaffolds with specific three-dimensional structures to guide the activities of cells. The study and application of biomimetic micro/nano-materials have greatly promoted the development of tissue engineering. This review aims to provide an overview of the different types of micro/nanomaterials, their preparation methods and their application in tissue regeneration.

Diabetic wound healing potential of silk sericin protein based hydrogels enriched with plant extracts

The complications associated with diabetic wounds make their healing process prolonged. Hydrogels could be ideal wound dressings therefore present research was conducted to prepare silk sericin (an adhesive protein polymer) based hydrogels in combination with plant extracts and to evaluate its effectiveness against wound healing process in mice with alloxan induced diabetes. Excision wounds were formed via a biopsy puncture (6 mm). Experimental hydrogels were prepared and applied topically on the diabetic wounds. All the hydrogel treatment groups showed significantly higher (P < 0.001) percent wound contraction from day 3 to day 11 as compared to the negative diabetic control group. The serum level of anti-inflammatory cytokine (Interleukin-10) and tissue inhibitor metalloproteinase (TIMP) was significantly higher (P < 0.001), while the level of pro-inflammatory cytokines (tumor necrosis factor-α, Interleukin-6) and matrix metalloproteinases (MMP-2, MMP-9) was significantly lower (P < 0.001) in hydrogels treatment groups as compared to diabetic control group. Although all the hydrogels showed effective results, however the best results were shown by 4 % sericin+4 % banyan+4 % onion based hydrogel. It can be concluded that Sericin based hydrogel enriched with banyan and onion extracts can be used as an effective remedy for the treatment of diabetic wounds due to their high healing and regenerative properties.

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.

Silk sericin as building blocks of bioactive materials for advanced therapeutics

Silk sericin is a class of protein biopolymers produced by silkworms. Increasing attention has been paid to silk sericin for biomedical applications in the last decade, not only because of its excellent biocompatibility and biodegradability but also due to the pharmacological activities stemming from its unique amino acid compositions. In this review, the biological properties of silk sericin, including curing specific diseases and promoting tissue regeneration, as well as underlying mechanisms are summarized. We consider the antioxidant activity of silk sericin as a fundamental property, which could account for partial biological activities, despite the exact mechanisms of silk sericin's effect remaining unknown. Based on the reactive groups on silk sericin, approaches of bottom-up fabrication of silk sericin-based biomaterials are highlighted, including non-covalent interactions and chemical reactions (reduction, crosslinking, bioconjugation, and polymerization). We then briefly present the cutting-edge advances of silk sericin-based biomaterials applied in tissue engineering and drug delivery. The challenges of silk sericin-based biomaterials are proposed. With more bioactivities and underlying mechanisms of silk sericin uncovered, it is going to boost the therapeutic potential of silk sericin-based biomaterials.

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.

Response surface optimization of enzymatic hydrolysis and ROS scavenging activity of silk sericin hydrolysates

CONTEXT

Sericin, a protein found in wastewater from the silk industry, was shown to contain a variety of biological activities, including antioxidant. The enzymatic conditions have been continuously modified to improve antioxidant effect and scavenging capacity against various free radicals of silk sericin protein.

OBJECTIVE

Variables in enzymatic reactions, including pH, temperature and enzyme/substrate ratio were analysed to discover the optimum conditions for antioxidant activity of sericin hydrolysates.

MATERIALS AND METHODS

Hydrolysis reaction catalysed by Alcalase^® was optimized through response surface methodology (RSM) in order to generate sericin hydrolysates possessing potency for % inhibition on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, ferric-reducing power and peroxyl scavenging capacity. Flow cytometry was performed to evaluate cellular ROS level in human HaCaT keratinocytes and melanin-generating MNT1 cells pre-treated either with 20 mg/mL RSM-optimized sericin hydrolysates or 5 mM N-acetyl cysteine (NAC) for 60 min prior exposure with 1 mM hydrogen peroxide (H₂O₂).

RESULTS

Among these three variables, response surface plots demonstrate the major role of temperature on scavenging capacity of sericin hydrolysates. Sericin hydrolysates prepared by using Alcalase^® at RSM-optimized condition (enzyme/substrate ratio: 1.5, pH: 7.5, temperature: 70 °C) possessed % inhibition against H₂O₂ at 99.11 ± 0.54% and 73.25 ± 8.32% in HaCaT and MNT1 cells, respectively, while pre-treatment with NAC indicated the % inhibition only at 30.26 ± 7.62% in HaCaT and 51.05 ± 7.14% in MNT1 cells.

DISCUSSION AND CONCLUSIONS

The acquired RSM information would be of benefit for further developing antioxidant peptide from diverse resources, especially the recycling of waste products from silk industry.

Hybrid membrane of flat silk cocoon and carboxymethyl chitosan formed through hot pressing promotes wound healing and repair in a rat model

Clinical wound management is always a relatively urgent problem. Moreover, wounds, especially severe wounds with excessive tension or excessive movement are prone to tissue infection, necrosis, and other negative effects during healing. Therefore, research has aimed to develop low-cost complementary treatments to address the urgent need for an innovative low-cost dressing that can adapt to high mechanical requirements and complex wound conditions. At present, tissue engineering to produce artificial skin with a structure similar to that of normal skin is one effective method to solve this challenge in the regeneration and repair of serious wounds. The present study hot pressed flat silk cocoons (FSC) with carboxymethyl chitosan (CMCS) to generate a cross-linked binding without enzymes or cross-linking agents that simulated the 3D structural composites of the skin cuticle. This hybrid membrane showed potential to reduce inflammatory cells and promote neovascularization in skin wound repair. After hot pressing at 130°C and 20 Mpa, the FSC/CMCS composite material was denser than FSC, showed strong light transmission, and could be arbitrarily cut. Simulating the normal skin tissue structure, the hybrid membrane overcame the poor mechanical properties of traditional support materials. Moreover, the combination of protein and polysaccharide simulated the extracellular matrix, thus providing better biocompatibility. The results of this study also demonstrated the excellent mechanical properties of the FSC/CMCS composite support material, which also provided a low-cost and environmentally friendly process for making dressings. In addition, the results of this study preliminarily reveal the mechanism by which the scaffolds promoted the healing of full-thickness skin defects on the back of SD rats. In vivo experiments using a full-thickness skin defect model showed that the FSC/CMCS membranes significantly promoted the rate of wound healing and also showed good effects on blood vessel formation and reduced inflammatory reactions. This bionic support structure, with excellent repair efficacy on deep skin defect wounds, showed potential to further improve the available biomaterial systems, such as skin and other soft tissues.

Toxicological evaluation of water-extract sericin from silkworm (Bombyx mori) in pregnant rats and their fetus during pregnancy

Sericin is a natural protein produced by the silkworm Bombyx mori, which has a wide range of biological activities and has a broad application prospect in multiple areas. However, systemic toxicity and safety assessment of sericin is still rare. This study was aimed to evaluate the toxic effects of water-extract sericin from cocoons of Bombyx mori in pregnant rats and their fetuses during pregnancy. Eighty pregnant rats were randomly divided into three treatment groups, one negative and one positive control group. The treatment groups were administered water-extract sericin solutions at doses of 1,000, 500, and 250 mg/kg, while the negative and positive control groups were administered pure water and 300 mg/kg aspirin, respectively. Rats were exposed daily by oral gavage from the seventh day of gestation for 10 consecutive days and sacrificed on the 20th day of gestation. The results showed that water-extract sericin did not induce any treatment-related changes on pregnant rats (clinical signs, body weights, food consumption, ovarian and uterine weights) and fetuses (body weights, body lengths, tail lengths, visceral, and skeletal development). The no-observed-adverse-effect-level (NOAEL) of sericin was determined to be 1,000 mg/kg body weight in rats. These results indicated that water-extract sericin is of low teratogenic potential under the experimental conditions of this study.

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.

Low Molecular Weight Sericin Enhances the In Vitro of Immunological Modulation and Cell Migration

Sericin, a waste product of the silk textile industry, has favorable physicochemical and biological properties. In this study, we extracted a low molecular weight (MW) sericin (LMW-sericin; below 10 kDa) by a performing high-temperature and high-pressure method and confirmed the MW using matrix-assisted laser desorption ionization-time of flight and liquid chromatography–mass spectrometry. Furthermore, we determined its biological effects on macrophages and human adipose stem cells (hASCs) as cell models to investigate the biocompatibility, immunomodulation behavior, and potential signaling pathway-related wound healing via analyses of gene expression of focal adhesion and human cytokines and chemokines using quantitative real-time polymerase chain reaction and cytokine assay. LMW-sericin showed good biocompatibility both in macrophages and hASCs. Macrophages cultured with 0.1 mg/ml LMW-sericin displayed an improved inflammatory response shown by the upregulation of CXCL9, IL12A, BMP7, and IL10, which developed Th1 and Th2 balance. LMW-sericin also improved the differentiation of macrophages toward the M2 phenotype by significantly enhancing the expression of Arg-1, which is conducive to the repair of the inflammatory environment. Moreover, the gene expression of hASCs showed that LMW-sericin promoted the secretion of beneficial adhesion molecules that potentially activate the gene transcription of differentiation and migration in hASCs, as well as significantly enhanced the levels of PKCβ1, RhoA, and RasGFR1 as fruitful molecules in wound healing. These findings provide insights into LMW-sericin application as a potential biomaterial for wound management.

Recycled Sericin Hydrolysates Modified by Alcalase® Suppress Melanogenesis in Human Melanin-Producing Cells via Modulating MITF

Because available depigmenting agents exhibit short efficacy and serious side effects, sericin, a waste protein from the silk industry, was hydrolyzed using Alcalase^® to evaluate its anti-melanogenic activity in human melanin-producing cells. Sericin hydrolysates consisted of sericin-related peptides in differing amounts and smaller sizes compared with unhydrolyzed sericin, as respectively demonstrated by peptidomic and SDS-PAGE analysis. The lower half-maximum inhibitory concentration (9.05 ± 0.66 mg/mL) compared with unhydrolyzed sericin indicated a potent effect of sericin hydrolysates on the diminution of melanin content in human melanoma MNT1 cells. Not only inhibiting enzymatic activity but also a downregulated expression level of tyrosinase was evident in MNT1 cells incubated with 20 mg/mL sericin hydrolysates. Quantitative RT-PCR revealed the decreased mRNA level of microphthalmia-associated transcription factor (MITF), a tyrosinase transcription factor, which correlated with the reduction of pCREB/CREB, an upstream cascade, as assessed by Western blot analysis in MNT1 cells cultured with 20 mg/mL sericin hydrolysates for 12 h. Interestingly, treatment with sericin hydrolysates for 6–24 h also upregulated pERK, a molecule that triggers MITF degradation, in human melanin-producing cells. These results warrant the recycling of wastewater from the silk industry for further development as a safe and effective treatment of hyperpigmentation disorders.

Urea-extracted sericin is potentially better than kojic acid in the inhibition of melanogenesis through increased reactive oxygen species generation

Background

Hyperpigmentation is a skin disorder, which is caused by an excess production of melanin. The reduction in melanin content without causing undesirable effects is required for the treatment of hyperpigmentation. Sericin is increasingly used as a hyperpigmentation treatment because of its antityrosinase activity. However, the various methods of sericin extraction have an effect on the composition and biological properties. The purpose of this study was to investigate the antioxidant and anti-melanogenic properties of sericin using different extraction methods including acid, base, heat, and urea extraction.

Methods

The chemical properties of extracted sericin were assessed in terms of amino acid components, thermal behavior, and UV–vis absorption. The inhibitory effects of sericin on melanogenesis were explored by determining the melanin content and cellular tyrosinase activity in B16F10 cells.

Results

Sericin from urea extraction provided different properties when compared with the other extraction methods. Our results indicate that urea-extracted sericin reduced the melanin content and cellular tyrosinase activity more effectively than the other extraction methods. Interestingly, the potential anti-melanogenic activity was more effective than kojic acid, a depigmenting agent used to treat hyperpigmentation. Moreover, treatment of urea-extracted sericin induced reactive oxygen species and subsequently activated antioxidant activity in B16F0 cells.

Conclusions

Our results present the potential inhibitory effect of urea-extracted sericin on melanogenesis. The therapeutic potential of urea-extracted sericin can be used in the treatment of hyperpigmentation and its complications.

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The anti-melanogenic effect of urea-extracted sericin was significantly better than kojic acid.

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Urea-extracted sericin suppressed melanin synthesis and tyrosinase activity through the induction of ROS.

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Urea-extracted sericin activated the expression of Nrf2 and its downstream target genes for modulation of melanogenesis.

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Urea-extracted sericin could be considered as an effective anti-melanogenic agent.

The antigenicity of silk-based biomaterials: sources, influential factors and applications

Silk is an ancient material with essential roles in numerous biomedical applications, such as tissue regeneration and drug delivery, because of its excellent tunable mechanical properties and diverse physical structures. In addition to the necessary functionalities for biomedical applications, another critical factor for materials applied in biology is the appropriate immune interactions with the body. This review focuses on the immune responses of silk-based materials applied in biomedical applications, specifically antigenicity. The factors affecting the antigenicity of silk-based materials are complicated and are related to the composition and structural characteristics of the materials. At the same time, the composition of silk-based materials varies with its species sources, such as silkworms, spiders, honey bees, or engineered recombinant silk. Additionally, different processing methods are used to fabricate different material formats, such as films, hydrogels, scaffolds, particles, and fibers, resulting in different structural characteristics. Furthermore, the resulting body reactions are also different with different degrees of the immune response. Silk protein typically induces a mild immune response, and immunogenicity can play active roles in osteogenesis, angiogenesis, and protection from inflammation. However, there are some rare reports of severe immune responses caused by silk, which can result in an allergic response or tissue necrosis. The source of allergenicity in silk-based materials is currently under-studied and how to regulate and eliminate the overreaction of the immune system is essential for further applications. Overall, the diverse characteristics of silk-based materials mostly show beneficial bioresponses with mild immunogenicity, and the tunable properties make it applicable in immune-related biomedical applications.

Effects of dipotassium glycyrrhizinate on wound healing

PURPOSE

Dipotassium glycyrrhizinate (DPG) has anti-inflammatory properties, besides promoting the regeneration of skeletal muscle. However, it has not been reported on skin wound healing/regeneration. This research aimed to characterize the effects of DPG in the treatment of excisional wounds by second intention.

METHODS

Male adults (n=10) and elderly (n=10) Wistar rats were used. Two circular wounds were excised on the dorsal skin. The excised normal skins were considered adult (GAN) and elderly (GIN) naïve. For seven days, 2% DPG was applied on the proximal excision: treated adult (GADPG) and elderly (GIDPG), whereas distal excisions were untreated adult (GANT) and elderly (GINT). Wound healing areas were daily measured and removed for morphological analyses after the 14th and the 21st postoperative day. Slides were stained with hematoxylin-eosin, Masson's trichrome, and picrosirius red.

RESULTS

Histological analysis revealed intact (GAN/GIN) and regenerated(GANT/GINT/GADPG/GIDPG) skins. No differences of wounds' size were found among treated groups. Epidermis was thicker after 14 days and thinner after 21 days of DPG administration. Higher collagen I density was found in GIDPG (14th day) and GADPG (21st day).

CONCLUSIONS

DPG induced woundhealing/skin regeneration, with collagen I, being more effective in the first 14 days after injury.

Incision Wound Healing Test of Ethanolic Extract Gel from Salaon (Parsonsia alboflavescens [Dennst.] Mabb.) Leaves in Male Rats

BACKGROUND: An incision wound is a wound caused by a sharp object. One of the plants that can be used as a traditional medicine for an incision wound is salaon leaves. The prepared form chosen is the gel because it is easy to use and its distribution is faster on the skin. AIM: The aim of the study was to explore whether salaon leaf extract gel meets the quality evaluation requirements and to know the effectiveness of ethanol extract gel of salaon (Parsonsia alboflavescens [Dennst] Mabb.) leaves to cure a scar on male rats. METHODS: Experimental method with salaon leaves as sample. Simplicia of salaon leaves extracted by maceration method, and then arenga gum gel-based formulation, afterward evaluation, and testing of its effectiveness on the healing of incision wound of male rats. Normal data were analyzed by the One Way Analysis of variance (ANOVA) and Post Hoc Tuckey Method. Kruskal-Wallis test used for abnormal data. RESULTS: The whole formula shows homogenous results, normal pH, stability, dissemination and good viscosity, less irritating, and with good adhesion. The results of a statistical analysis of the wound on the 8th day with ANOVA test indicate a significant difference between the five groups p = 0.000 (p < 0.05) and Post-Hoc Tukey Honest Significant Difference test results obtained a concentration of 5% not significantly different from the positive control Placenta extract gel. The optimum dose that can heal incision wound in male rats is 5%. CONCLUSION: The whole formulation qualifies for the quality of the gel formulation. Ethanol extract gel of salaon leaves can heal wound on male rats and the optimal dose is 5%.

Semi-Solid Product of Medicinal Leech Enhances Wound Healing in Rats

Background: Wound causes a series of cascading reactions such as cellular damage, inflammatory reactions, and infection. Objectives: The present study aimed to prepare pharmaceutical skin product from lyophilized Hirudo orientalis leech source with active enzyme and proteins, having wound healing and anti-coagulation activities. Methods: The present study focused on the bioactive protein of Hirudo orientalis with anti-trypsin and anti-coagulation activity. First, biological active substance was prepared from lyophilized leech conducted on resultant 5% leech cream. Skin absorption of 5% leech cream was evaluated by Franz cell test, and in vivo wound healing capability of the leech cream was compared with phenytoin cream. In addition, the microbial control of final product was summed-up. Further, the quality control analysis and protein purification in final product were conducted using elution procedure on Hirudin protein-related region. Finally, the anticoagulant activity of the resultant protein was observed. Results: Using the result of the experiments investigating the successful effect containment function of the trypsin, we established the decreased rate of UV absorption in the area of 410 nm in question based on increases in the amount of cream. With 0, 100, 200 and 300 mg of 5% leech cream, absorbance (A) rate was: A (1.9, 1.47, 0.753 and 0.00) (P < 0.05; √2 = 21.6). In anticoagulation activity increased rate of partial thromboplastin time (PTT) (sec) (mean ± SEM), (26 ± 0.00, 34.22 ± 0.61 and 42 ± 0.71) with the 0, 100, and 200 mg final product was established. No bacterial colony growth was observed in the microbial culture analysis. In vivo results demonstrated that leech cream and phenytoin could promote wound regeneration by accelerating the re-epithelialization process and initial angiogenesis among all treatment groups. Conclusions: In the wound healing, we usually seek to reduce pain and inflammation, beside epitelialization and angiogenesis. Leech saliva contains biological substances that we have proven in this study. Our expectations for wound healing will be met with this pharmaceutical product citing the result of this study. The leech product proved to be the best selection for cosmetic with the added capabilities of renovation of the hair glands and regular skin form and typical depth of outer layer of skin. Thus, the leech cream can be considered as a better substitute for the conventional wound healing products.

Naturally-derived targeted therapy for wound healing: Beyond classical strategies

This review summarizes the four processes of wound healing in the human body (hemostasis, inflammatory, proliferation, and remodeling) and the most current research on the most important factors affecting cutaneous wound healing and the underlying cellular and/or molecular pathways. Local factors, including temperature, oxygenation, and infection, and systemic factors, such as age, diabetes, sex hormones, genetic components, autoimmune diseases, psychological stress, smoking and obesity are also addressed. A better understanding of the role of these factors in wound repair could result in the development of therapeutics that promote wound healing and resolve affected wounds. Additionally, natural products obtained from plants and animals are critical targets for the discovery of novel biologically significant pharmacophores, such as medicines and agrochemicals. This review outlines the most recent advances in naturally derived targeted treatment for wound healing. These are plant-derived natural products, insect-derived natural products, marine-derived natural products, nanomaterial-based wound-healing therapeutics (metal- and non-metal-based nanoparticles), and natural product-based nanomedicine to improve the future direction of wound healing. Natural products extracted from plants and animals have advanced significantly, particularly in the treatment of wound healing. As a result, the isolation and extraction of bioactive compounds from a variety of sources can continue to advance our understanding of wound healing. Undescribed bioactive compounds or unexplored formulations that could have a role in today's medicinal arsenal may be contained in the abundance of natural products and natural product derivatives.

Identification and location of sericin in silkworm with anti-sericin antibodies

Sericin, as the main component of silkworm cocoon silk, surrounds and protects the silk fibroin. Sericin is a natural macromolecular protein complex encoded by the genes Ser1, Ser2, and Ser3. At present, there are no available antibodies against sericin that may be used to identify and locate it at the protein level, hindering the study of its secretion mechanism and materials application. Therefore, the development of effective antibodies against sericin is an urgent necessity. To address this problem, we prepared polyclonal antibodies against the Ser1, Ser2 and Ser3 proteins using synthesized peptides for the first time. The specificity of the antibodies was confirmed using dot blot, immunoblotting and mass spectrometry on the hybrid bands of the middle silk gland. The immunoblotting results of anti-sericin antibodies showed that sericin has different molecular weights in different regions of the middle silk gland and strains in the 5th instar. Through immunohistochemistry, anti-sericin antibodies revealed that sericin presented different distributions in the anterior part of the middle silk gland of 872 strain at the 7th day of 5th instar. In addition, the prepared antibodies not only detected intact sericin molecules, but also detected degraded sericin that was dissolved in five different solvents. In summary, this work prepared effective sericin antibodies for silk protein synthesis and secretion research and provides a possible molecular detection method for biological products containing silkworm sericin.

The Effect of Botulinum Toxin on Flap Viability of the Posterior Thigh Perforator Flap in Rats

BACKGROUND

The use of perforator propeller flaps in lower limb reconstruction has increased recently. Many pharmacological agents are used to increase flap viability. Botulinum toxin has been used in various types of flaps in the literature. However, there is no study regarding the use of botulinum toxin in the lower limb propeller flaps. This study investigates the effect of botulinum toxin administration on flap survival for lower limb propeller flap in rats.

MATERIALS AND METHODS

The study included 20 male Wistar albino rats, divided into two groups with a flap rotation of 90° in group 1 and 180° in group 2. In both groups, botulinum toxin was administered to the right thigh and a physiological saline solution was applied to the left thigh. Five days later, flaps were elevated over the posterior aspect of the right and left thighs and inset after 90° and 180° rotation was performed. Histopathological, immunohistochemical, and necrosis area analyses were performed.

RESULTS

Necrosis area, edema, polymorphonuclear leukocyte infiltration, and necrosis were found to be higher on the left side of the groups, whereas epidermal thickness, collagen density, vascularization, and hair root density were found to be higher on the right side of the groups. No significant difference was found between the right posterior thighs in either group on any parameter other than vascularization. Histopathologically and immunochemically statistically significant differences were found between the two groups.

CONCLUSIONS

The present study found that botulinum toxin increases flap viability in lower limb perforator-based propeller flaps.

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-Induced Melanogenesis in Cultured Retinal Pigment Epithelial Cells Is Associated with Elevated Levels of Hydrogen Peroxide and Inflammatory Proteins

We previously demonstrated that the silk protein sericin promotes pigmentation of retinal pigment epithelium (RPE) by activating the NF-κB pathway. Among numerous agents, NF-κB can be activated by hydrogen peroxide. In the present study, we explored possible associations between reactive oxygen species and sericin-induced melanogenesis in RPE. The proteome of human fetal RPE cultured for seven days with or without 1% sericin was analyzed using ingenuity pathway analysis (IPA). The proteomic data was verified by immunofluorescence and immunoblotting. Light microscopy and scanning electron microscopy were used to assess morphology. Dihydroethidium (DHE) and dihydrorhodamine (DHR) assays were used to measure superoxide and hydrogen peroxide species. Expression levels of proteins related to inflammation, differentiation, cell survival and cell adhesion were higher in cells cultured in Dulbecco's Modified Eagle Medium (DMEM) with 1% sericin, whereas cells cultured in DMEM alone showed higher expression levels of proteins associated with Bruch's membrane and cytoskeleton. Despite upregulation of inflammatory proteins, sericin co-cultured RPE yielded significantly higher cell viability compared to cells cultured without sericin. Addition of sericin to culture media significantly increased hydrogen peroxide-levels without significantly affecting superoxide-levels. We suggest that sericin-induced melanogenesis in cultured RPE is associated with elevated levels of superoxide dismutase, hydrogen peroxide and inflammatory proteins.

Quantification of silk protein using phage nanofibers with high binding specificity

Silk sericin (SS) has emerged as an important silk protein for use in medicine and textiles. However, no sensitive method is available for detecting it. Here, we employed phage nanofibers (∼7 nm wide) as a probe to quantify SS from a dilute aqueous solution by exploiting two properties of the bacteria-infecting phage nanofibers, its use as a platform for discovering SS-binding peptide and its ultrasensitive quantification by a simple titering assay (where the number of phage nanofibers displaying the SS-binding peptide is equal to the number of countable millimeter-sized plaques derived from the phage nanofibers by infecting bacteria through plating). We first discovered a SS-binding peptide and the phage nanofibers (SS-phage) displaying this peptide at the tip. We found that this peptide can even differentiate SS from another silk protein (silk fibroin), showing its high specificity. We then employed SS-phage nanofibers as a probe to bind the SS casted from the aqueous solution. Because SS-phage nanofibers bound to the SS and the SS in the original SS solution were numerically correlated and the number of SS-phage nanofibers can be determined by counting the plaques in a Petri dish by the titering assay, determining the number of phage-derived plaques with the naked eye led to the rapid quantification of SS concentration with a detection limit of 19.50 ng ml^-1. This phage-based counting strategy can be potentially applied to the facile detection of other proteins.

The Efficacy and Safety of Different Sericin Doses for Pleurodesis

BACKGROUND

The aim of present study is to compare the effectiveness, side-effect potential of different doses of sericin pleurodesis.

METHODS

Adult, male, 12-week-old, Wistar-albino rats (n=52), were randomly-divided into four-groups, referred to A, B, C and D. Sericin was administrated at different doses through left thoracotomy, with 15mg sericin to Group-A, 30mg to Group-B and 45mg to Group-C. Group-D was assigned as control group. The rats were sacrificed 12 days later. Left-hemithorax, heart, liver and kidney were examined pathologically.

RESULTS

No foreign body reaction in the parenchyma was observed in any of the rats, while emphysema was least common in Group-B (P<.05). Multi-layer mesothelium of both pleura was most common in Group-B, while fibrosis and fibrin organization within the visceral-pleura was more successful in all of sericin treated groups than in control group (P<.05), with neither Group-A, Group-B nor Group-C being superior to each other. In the examination of collagen fibers using Masson's trichrome, "dense collagen fibers" were found in all three sericin treated groups, and differences between Groups-A, -B, -C and the control group were significant (P<.05). The probability of observing pyknotic nucleus and balloon degeneration in liver increased with increasing sericin doses (P<.05). Glomerular degeneration in kidney and the findings of pericarditis were most common in Group-C (P<.05).

CONCLUSION

The target should be to maximize efficacy while minimizing the likelihood of side-effects. The intrapleural administration of sericin 30mg performs better due to multi-layer mesothelial reaction being higher and emphysema being lower in Group-B, to the fewer side-effects affecting the kidney and heart, and liver toxicity not being higher.

Diligent profiling of preclinical safety of the silk protein sericin

BACKGROUND

Sericin is a widely used protein in the pharmaceutical industry derived from the silkworm, Bombyx mori, and used for the treatment of various diseases and pathological conditions. It is the main ingredient of the Unani preparation khameera abresham. The study was conducted to evaluate the preclinical toxicity of the silk protein sericin in mice.

METHODS

In the acute toxicity study, sericin was administered once orally to different groups of animals at doses of 500, 1000, and 2000 mg/kg. Animals were observed for 14 days. In the sub-acute toxicity study, sericin was administered in mice for 4 weeks in the toxic group at doses of 500, 1000, and 2000 mg/kg, while in the recovery group it was administered for 4 weeks at doses of 500 and 2000 mg/kg followed by 2 weeks of distilled water administration.

RESULTS

In the acute toxicity study, the observed parameters showed no significant difference, and no mortality was reported. In the sub-acute toxicity study, there were no toxicological effects in any of the estimated parameters, while histopathological analysis showed inflammation in vital organs at the dose of 2000 mg/kg.

CONCLUSIONS

Results of our acute toxicity study suggest that sericin is safe at all administered doses, while the sub-acute study suggests that the NOAEL (no-observed-adverse-effect level) of sericin is below 2000 mg/kg, at which it can be considered safe.

The Effects of Sildenafil and/or Nitroglycerin on Random-pattern Skin Flaps After Nicotine Application in Rats

Smoking aggravates skin necrosis as a complication of random-pattern flap ischaemia. Sildenafil and nitroglycerin (NTG) are vasodilator agents that may affect skin flap survival. Fifty rats were subjected to a dorsal random-pattern flap operation and randomly divided into 5 groups. The control group received no treatment. The ischaemic group were administered local nicotine injections. The sildenafil group were administered oral sildenafil treatment in addition to the same intervention as the ischaemic group. The NTG group received topical NTG ointment application instead of sildenafil. The combined group were given both sildenafil and NTG treatments. After 7 days, all rats were sacrificed for flap assessment. Flap survival percentages at the 3^rd and 7^th days were significantly higher in the combined group than in the other study groups. Histologically, the ischaemic group exhibited dermal disorganization and inflammatory cell infiltration, which were improved in the 3 treated groups; however, the combined group presented the most relevant effect. The epidermal thickness showed a decrease in the ischaemic group (23.1 μm) that was significantly increased in the sildenafil (28.4 μm), NTG (28.8 μm) and combined (35.8 μm) groups. Immunohistochemically, the combined group exhibited a significant decrease in the apoptotic index and an increase in the proliferative index (2.3 and 56.9%, respectively) compared to those in the ischaemic (63.2 and 3%), sildenafil (41.7 and 28.1%) and NTG (39.3 and 30.4%) groups. Transmission electron microscopy (TEM) showed that the combined group displayed improvement in most of the ischaemic changes. Our analyses suggest that the combined use of sildenafil and NTG is more efficacious than using only one of these treatments for skin flap survival.

An evaluation of the effects of caffeic acid phenethyl ester and Ankaferd blood stopper on secondary wound healing of oral mucosal tissue

Background/aim

Caffeic acid phenethyl ester (CAPE) and Ankaferd Blood Stopper (ABS) are considered to contribute to wound healing. The purpose of this study was to investigate the effect of ABS and CAPE on secondary wound healing of oral mucosal tissue.

Materials and methods

In total, 63 male Sprague-Dawley rats were used in this study. The animals were randomly divided into three groups and anaesthetized with ketamine (8 mg/100 g, intraperitoneally): a control group, CAPE group, and ABS group. A full-thickness excisional wound was created using a 4 mm punch biopsy tool. Topical ABS and CAPE were then applied in each group for 7, 14, and 21 days (n = 7 in each group). The animals in each group were sacrificed after 7, 14, and 21 days. Palatal specimens were stained with haematoxylin-eosin. Vascular endothelial growth factor (VEGF) and tumour necrosis factor-inducible gene 6 (TSG-6) protein expressions were determined using the Western blot method.

Results

Inflammation, vessel dilatation, and haemorrhages were significantly lower in the CAPE group as compared with these parameters in the other groups (P < 0.05). Fibrosis was significantly higher in the ABS group as compared with that in the other groups (P < 0.05). VEGF protein levels were elevated in the 21-day CAPE group and 7-day ABS group. The expression of TSG-6 increased in the 7-day CAPE group and 21-day ABS group.

Conclusion

Based on our findings, ABS and CAPE had positive effects on the oral wound healing process.

THE ACTION OF SERICIN PROTEIN ON INITIAL NERVE REPAIR, ASSOCIATED OR NOT WITH SWIMMING IN WISTAR RATS

ABSTRACT Objective: To analyze the effects of sericin treatment, associated or not with swimming with load exercise, on initial sciatic nerve repair after compression in Wistar rats. Methods: Forty animals were divided into five groups: control, injury, injury-sericin, injury-swimming and injury-sericin-swimming. During the axonotmesis procedure, the sericin was applied to the injury-sericin and injury-sericin-swimming groups. The injury-swimming and injury-sericin-swimming groups performed the swimming with load exercise for five days, beginning on the third postoperative day (PO), and were evaluated for function, nociception and allodynia. Euthanasia was performed on the 8th PO day and fragments of the nerve were collected and prepared for quantitative and descriptive analysis in relation to the total amount of viable nerve fibers and non-viable nerve fibers, nerve fiber diameter, axon diameter and myelin sheath thickness. Results: There was no significant improvement in the sciatic functional index up to the eighth day. The Von Frey test of the surgical scar and plantar fascia indicated a reduction in pain and allodynia for the injury-swimming and injury-sericin-swimming groups. The morphological analysis presented similar characteristics in the injury-sericin, injury-swimming and injury-sericin-swimming groups, but there was a significant difference in the number of smaller non-viable nerve fibers in the injury-swimming and injury-sericin-swimming groups as compared to the others. Conclusions: Isolated sericin protein presented proinflammatory characteristics. There was improvement of allodynia and a decrease in the pain at the site of the surgical incision, possibly linked to an aquatic effect. There was no acceleration of nerve repair on the eighth day after the injury. Level of Evidence I; High quality randomized clinical trial with or without statistically significant difference, but with narrow confidence intervals.

Sumatriptan Increases Skin Flap Survival through Activation of 5-Hydroxytryptamine 1b/1d Receptors in Rats: The Mediating Role of the Nitric Oxide Pathway

BACKGROUND

Random pattern skin flaps are applicable for reconstructing any defect in plastic surgery. However, they are difficult to apply because of necrosis. Sumatriptan, a selective 5-hydroxytryptamine 1b/1d agonist, is routinely used to offset acute migraine attacks. Recent studies have suggested that sumatriptan may induce vasodilation at lower concentrations. The authors' aim is to investigate the effect of sumatriptan on skin flap survival and the role of nitric oxide in this phenomenon.

METHODS

Seventy-two male Sprague-Dawley rats were divided into eight groups. Increasing doses of sumatriptan (0.1, 0.3, and 1 mg/kg) were given intraperitoneally to three different groups after dorsal random pattern skin flaps were performed. To assess the exact role of 5-hydroxytryptamine 1b/1d receptors, GR-127935 was administered solely and with sumatriptan. N-ω-nitro-L-arginine methyl ester (L-NAME, a nonselective nitric oxide synthase inhibitor) was used to evaluate any possible involvement of nitric oxide in this study. All rats were examined 7 days later.

RESULTS

The authors' results demonstrated that flap survival was increased by lower doses of sumatriptan compared to a control group for both 0.3 mg/kg (p = 0.03, mean difference = 32, SE = 8) and 0.1 mg/kg (p = 0.02, mean difference = 26, SE = 8). This protective effect was eliminated by coadministration of GR-127935 or N-ω-nitro-L-arginine methyl ester with sumatriptan. Histopathologic studies revealed a significant increase in capillary count and collagen deposition and a decreased amount of edema, inflammation, and degeneration.

CONCLUSIONS

Sumatriptan in lower concentration increases skin flap survival by means of activation of 5-hydroxytryptamine 1b/1d receptors. This effect is mediated through the nitric oxide synthase pathway.

Inhibitory role of silk cocoon extract against elastase, hyaluronidase and UV radiation-induced matrix metalloproteinase expression in human dermal fibroblasts and keratinocytes

Topical delivery of potent antioxidants maintain the redox balance of the skin, which leads to the downregulation of matrix metalloproteinase (MMP) expression and prevents UV radiation-induced photoaging. In this study, we aimed at investigating the inhibitory role of silk cocoon extract (SCE) isolated from the Antheraea assamensis (AA), Bombyx mori (BM), and Philosamia ricini (PR) silk varieties against UV radiation-induced MMP expression. Incubation of elastase and hyaluronidase with Antheraea assamensis silk cocoon extract (AASCE) caused 50% inhibition of activity. The assessment of total collagen content using the Sirius red assay showed that AASCE (10 μg mL-1) and Philosamia ricini silk cocoon extract (PRSCE at 100 μg mL-1 concentration) post-treatment significantly enhanced the total collagen content in UVA1 and UVB irradiated HDF cells, whereas BM silk cocoon extract (BMSCE at 100 μg mL-1 concentration) post-treatment significantly enhanced the total collagen content in UVA1-irradiated HDF cells. Gene expression studies revealed AASCE and PRSCE post-treatment downregulated the expression of interleukin (IL)-6, MMP-1 and upregulated procollagen genes in UV irradiated HDF cells. Gelatin zymography studies with AASCE post-treatment downregulated the release of MMP-2 and MMP-9 by HaCaT cells. The overall results validate AASCE efficiently shielding UV radiation-induced collagen and elastin degradation by downregulation of MMP expression, substantiating its further use as a potent antioxidant complement in skin care formulations.

Sericin silk protein in peripheral nervous repair associated with the physical exercise of swimming in Wistar rats

OBJECTIVE

To verify the action of sericin associated to swim exercise with overload, on sciatic nerve repair in Wistar rats, after 22 days of nerve compression.

METHODS

Forty animals been composed of five groups: control, injury, injury-sericin, injury-swimming and injury-sericin-swimming. During the lesion procedure, sericin, in hydrolyzed form, applied directly to the injury in the injury-sericin and injury-sericin-swimming groups. Injury-swimming and injury-sericin-swimming groups underwent to 5 days per week for 3 weeks, with a 10% overload of the animal's body weight, and a weekly progressive evolution of swimming time, lasting 15, 20 and 25 min/day. Pre and throughout the treatment period the animals performed evaluation of sciatic functional index and pressure pain threshold with digital von Frey filament. Euthanasia was performed on the 22nd postoperative day, and two fragments of the nerve were collected and prepared for descriptive and quantitative analysis.

RESULTS

The sciatic functional index assessment showed significant differences in the motor function of the control until the 14th day. Regarding the allodynia, there was revealed a significant improvement in injury-swimming performance relative to injury, injury-sericin and injury-sericin-swimming, and the number of viable and non-viable nerve fibers smaller than 4 μm in diameter was significantly higher in the injury-sericin-swimming.

CONCLUSION

swimming showed a better evolution of the nociceptive threshold and allodynia. Sericin treatment had exacerbated pro-inflammatory characteristics. On the other hand, the association of sericine and swimming showed a possible regulatory effect by resting swimming exercise, with a significant increase of fibers of smaller diameter.

Histological Evaluation of Direct Pulp Capping with Silk Sericin: A Preliminary Animal Study

Introduction

This histological study analyzed silk sericin as a potential direct pulp capping biomaterial in contact with pulp and comparing its response to calcium hydroxide.

Methods and Materials

Twenty maxillary first molars from Wistar male rats were used, with 60 days of age, between 200 and 300 gr, which were divided in 4 groups (n=5): G1 and G3, controls, capped with calcium hydroxide in 7 and 30 days, respectively; G2 and G4, capped with silk sericin in 7 and 30 days, respectively. Circular cavities were prepared for pulp exposure, where capping materials were applied, being posteriorly restored with glass ionomer cement. After completion of each observation period, the animals were sacrificed and molars were histologically processed for analysis in light microscopy to evaluate presence of necrosis in pulp tissue, inflammatory cells infiltration and tertiary dentin formation. Data analysis was carried out using Kruskal-Wallis and Dunn's post hoc tests.

Results

After 7 days, there was less necrosis and inflammatory cells infiltration in G1 when compared to G2 (P=0.007 and P=0.008, respectively). After 30 days, a sample of G3 induced tertiary dentin formation and G4 showed decrease in inflammation (P=0.041) compared to G2.

Conclusion

Among the determined experiment conditions, it was concluded that contact between silk sericin and pulp tissue showed improved inflammatory response throughout treatment and new cells proliferation. However, silk sericin adhibition in pure form did not show capability for induction of tertiary dentin formation.

Does Sericin, as a Novel Pleurodesis Agent, Have Higher Effectiveness Compared to Talcum Powder, Doxycycline, and Silver Nitrate Pleurodesis?

INTRODUCTION

The usefulness of sericin as pleurodesis agent has previously been described. Present study aims to compare sericin pleurodesis regarding success, effectiveness, tolerability, and side-effects.

METHODS

Adult, 12-week-old Wistar-albino rats (n=60), divided to five groups as sericin, talcum-powder, doxycycline, silver-nitrate and control. Agents were administrated through left thoracotomy, rats sacrificed twelve-days after.

RESULTS

Highest ratio of collagen fibers was observed in sericin group, and the intensity was higher than talcum-powder group (p<0.05). Compared to silver nitrate, sericin group displayed better mesothelial reaction, and multi-layer mesothelium was also better (p<0.05). Foreign body reaction and emphysema were less frequent in sericin group (p<0.05). The presence of biological tissue in parenchyma was less prominent in sericin group (p<0.05). Foreign body reaction on thoracic wall was less common in sericin group (p<0.05). Presence of biological tissue glue in thoracic wall was less prominent in sericin group (p<0.05). Glomerular degeneration was lower in sericin group compared to the silver nitrate group (p<0.05), and tubular degeneration was less common in sericin group than talcum group (p<0.05). Pericarditis was less common in sericin group compared to the other groups (p<0.05).

CONCLUSION

As an intrinsic, natural glue protein, sericin protects the lung parenchyma and tissues, and its glue-like characteristics enable pleurodesis. The success of sericin in pleurodesis was demonstrated in the present study based on investigations of the pleurae. Being cost-effective and better tolerated agent associated with a low potential of side effects, sericin is more effective, less expensive and provides more lung parenchyma protection.

A Comparison of Three Methods for the Analysis of Skin Flap Viability: Reliability and Validity

Objective: Technological advances have provided new alternatives to the analysis of skin flap viability in animal models; however, the interrater validity and reliability of these techniques have yet to be analyzed. The present study aimed to evaluate the interrater validity and reliability of three different methods: weight of paper template (WPT), paper template area (PTA), and photographic analysis. Approach: Sixteen male Wistar rats had their cranially based dorsal skin flap elevated. On the seventh postoperative day, the viable tissue area and the necrotic area of the skin flap were recorded using the paper template method and photo image. The evaluation of the percentage of viable tissue was performed using three methods, simultaneously and independently by two raters. The analysis of interrater reliability and viability was performed using the intraclass correlation coefficient and Bland Altman Plot Analysis was used to visualize the presence or absence of systematic bias in the evaluations of data validity. Results: The results showed that interrater reliability for WPT, measurement of PTA, and photographic analysis were 0.995, 0.990, and 0.982, respectively. For data validity, a correlation >0.90 was observed for all comparisons made between the three methods. In addition, Bland Altman Plot Analysis showed agreement between the comparisons of the methods and the presence of systematic bias was not observed. Innovation: Digital methods are an excellent choice for assessing skin flap viability; moreover, they make data use and storage easier. Conclusion: Independently from the method used, the interrater reliability and validity proved to be excellent for the analysis of skin flaps' viability.

Effects of Normovolemic Hemodilution on Survival of Skin Flaps: An Experimental Study

Background

The aim of this study was to investigate the effects of various ratios of hemodilution on the survival of McFarlane’s skin flaps.

Material/Methods

An experimental study was performed on 42 adult male Wistar rats (weighing 260 to 305 g) allocated to a control group without any volume loss and to 6 study groups with hemodilution ratios of 5%, 10%, 15%, 20%, 25%, and 30%. In all subjects, random-pattern McFarlane’s skin flaps were uniformly elevated and re-sutured to the donor sites. The amount of necrosis was evaluated on the 7^th day postoperatively and compared among the groups.

Results

The amounts of flap necrosis in the groups with 5%, 10%, 15%, and 20% hemodilution ratios were significantly lower than that of the control group (p<0.001). In the 25% and 30% hemodilution groups, although there was less necrosis than in the control group, the differences were not statistically significant. Hematocrit levels, which initially decreased in conjunction with the hemodilution ratios, returned to normal levels on the 7^th day after the operation.

Conclusions

Our results indicated that 20% or less of the total blood volume loss that may be compensated by the normovolemic hemodilution with dextran can improve flap survival.

Preparation and characterization of gelatin/sericin/carboxymethyl chitosan medical tissue glue

Background:

The development and application of medical glue has been continuously expanding and advancing. However, there are few glues that combine low-cost with excellent biocompatibility.

Methods:

We have prepared a medical tissue glue using a gelatin (Gel), sericin (SS) and carboxymethyl chitosan (CMCS) blend solution, cross-linked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC). The combination’s characteristics and microstructure morphology were observed by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). Bond strength tests were used to measure the bond strength of the glue. To assay blood compatibility, a hemolytic test, dynamic coagulation test and platelet adherence test were also investigated. Further, the cellular behavior of L-929 and a systemic acute toxicity test on the Gel/SS/CMCS tissue glue were also investigated by MTT and H&E staining.

Results:

Characterization analysis showed that there was stable binding between raw materials, forming an amide bond with homogeneous holes. The bond strength of the tissue glue reached 2.50 ± 0.04 N in 10 minutes, slightly higher than the alpha-cyanoacrylate biological glue (2.25 ± 0.05 N). Blood compatibility tests revealed that the glue had outstanding blood compatibility. Further, cytotoxicity test and systemic acute toxicity test both showed that the glue was without cytotoxicity and not toxic to the body.

Conclusions:

The Gel/SS/CMCS tissue glue we prepared at low cost had excellent biocompatibility and structural characteristics. It could be a better candidate for tissue engineering in biomedical applications applied in clinical practice to promote skin wound healing and to further reduce the formation of skin wound scars.

A study of long-term stability and antimicrobial activity of chlorhexidine, polyhexamethylene biguanide, and silver nanoparticle incorporated in sericin-based wound dressing

In this study, three kinds of antiseptics which were 0.05% chlorhexidine, 0.2% polyhexamethylene biguanide (PHMB), or 200 ppm silver nanoparticle was introduced to incorporate in the sericin-based scaffold to produce the antimicrobial dressing for the treatment of infected chronic wound. The effects of antiseptic incorporation on the stability, release of sericin, and short-term and long-term (6 months) antimicrobial activity of the sericin dressing against gram-negative and gram-positive bacteria were investigated. We showed that the incorporation of each antiseptic did not have significant effect on the internal morphology (pore size ~ 73-105 μm), elasticity (Young's modulus ~ 200-500 kPa), and the sericin release behavior of the sericin-based dressing. The release of sericin from the dressing was prolonged over 120 h and thereafter. Comparing among three antiseptics, 0.05% chlorhexidine incorporated in the sericin dressing showed the highest immediate and long-term (6 months) antimicrobial effect (largest inhibition zone) against most bacteria either gram-positive or gram-negative bacteria. The in vivo safety test following ISO10993 standard (Biological evaluation of medical devices - Part 6: Tests for local effects after implantation) confirmed that the sericin dressing incorporating 0.05% chlorhexidine did not irritate to tissue, comparing with the commercial material used generally in clinic (Allevyn®, Smith & Nephew). We suggested the sericin dressing incorporating 0.05% chlorhexidine for the treatment of infected chronic wound. Chlorhexidine would reduce the risk of infection while the sericin may promote wound healing.