Silver nanoparticles/chitosan oligosaccharide/poly(vinyl alcohol) nanofiber promotes wound healing by activating TGFβ1/Smad signaling pathway

Green synthesis of silver and iron oxide nanoparticles mediated photothermal effects on Blastocystis hominis

The evolution of parasite resistance to antiparasitic agents has become a serious health issue indicating a critical and pressing need to develop new therapeutics that can conquer drug resistance. Nanoparticles are novel, promising emerging drug carriers that have demonstrated efficiency in treating many parasitic diseases. Lately, attention has been drawn to a broad-spectrum nanoparticle capable of converting absorbed light into heat via the photothermal effect phenomenon. The present study is the first to assess the effect of silver nanoparticles (Ag NPs) and iron oxide nanoparticles (Fe3O4 NPs) as sole agents and with the combined action of the light-emitting diode (LED) on Blastocystis hominins (B. hominis) in vitro. Initially, the aqueous synthesized nanoparticles were characterized by UV-Vis spectroscopy, zeta potential, and transmission electron microscopy (TEM). The anti-blastocyst efficiency of these NPs was tested separately in dark conditions. As these NPs have a wide absorption spectrum in the visible regions, they were also excited by a continuous wave LED of wavelength band (400-700 nm) to test the photothermal effect. The sensitivity of B. hominis cysts was evaluated using scanning laser confocal microscopy whereas the live and dead cells were accurately segmented based on superpixels and the k-mean clustering algorithm. Our findings showed that this excitation led to hyperthermia that induced a significant reduction in the number of cysts treated with photothermally active NPs. The results of this study elucidate the potential role of photothermally active NPs as an effective anti-blastocystis agent. By using this approach, new therapeutic antiparasitic agents can be developed.

Mechanisms and Optimization Strategies of Paracrine Exosomes from Mesenchymal Stem Cells in Ischemic Heart Disease

The morbidity and mortality of myocardial infarction (MI) are increasing worldwide. Mesenchymal stem cells (MSCs) are multipotent stem cells with self-renewal and differentiation capabilities that are essential in tissue healing and regenerative medicine. However, the low implantation and survival rates of transplanted cells hinder the widespread clinical use of stem cells. Exosomes are naturally occurring nanovesicles that are secreted by cells and promote the repair of cardiac function by transporting noncoding RNA and protein. In recent years, MSC-derived exosomes have been promising cell-free treatment tools for improving cardiac function and reversing cardiac remodeling. This review describes the biological properties and therapeutic potential of exosomes and summarizes some engineering approaches for exosomes optimization to enhance the targeting and therapeutic efficacy of exosomes in MI.

Physicochemical properties and cell proliferation and adhesive bioactivity of collagen-hyaluronate composite gradient membrane

Membrane materials were widely used in guided tissue regeneration (GTR) to prevent fibroblast invasion and form a confined area for preferentially growing of osteoblast. A novel collagen-hyaluronate composite gradient membrane was prepared by Tilapia (Oreochromis mossambicus) skin collagen and sodium hyaluronate for potential GTR applications and their bioactivities were investigated by cellular viability. SEM results indicated the membrane showed a dense outer and a porous inner surface for effectively guiding the growth of bone tissue. Physicochemical and biosafety experiments showed the tensile strength of membrane was 466.57 ± 44.31 KPa and contact angle was 74.11°, and the membrane showed perfect biocompatibility and cytocompatibility as well, which met the requirements of GTR material. Cell morphology revealed that the membrane could facilitate the adherence and proliferation of fibroblast and osteoblast. The results of qRT-PCR and ELISA demonstrated that the membrane could effectively activate TGF-β/Smad pathway in fibroblast, and promote the expressions of TGF-β1, FN1 and VEGF. Remarkably, RUNX2 was stimulated in BMP2 pathway by the membrane to regulate osteoblast differentiation. In summary, the collagen-hyaluronate composite gradient membrane not only fulfills the prerequisites for use as a GTR material but also demonstrates substantial potential for practical applications in the field.

Combined Silver Sulfadiazine Nanosuspension with Thermosensitive Hydrogel: An Effective Antibacterial Treatment for Wound Healing in an Animal Model

Introduction

Silver sulfadiazine (AgSD) is widely used in burn wound treatment due to its broad-spectrum antibacterial activity. However, its application in wound healing is greatly hindered by the low solubility of AgSD particles and their cellular cytotoxicity. Herein, we studied the safety and in vivo efficacy of nano-sized silver sulfadiazine loaded in poloxamer thermosensitive hydrogel (NS/Gel).

Methods

In NS/Gel, silver sulfadiazine was prepared into silver sulfadiazine nanosuspension (NS) to improve the solubility and enhance its antibacterial activity, whereas the poloxamer thermosensitive hydrogel was selected as a drug carrier of NS to achieve slow drug release and reduced cytotoxicity. The acute toxicity of silver sulfadiazine nanosuspension was first evaluated in healthy mice, and its median lethal dose (LD₅₀) was calculated by the modified Karber method. Furthermore, in vivo antibacterial effect and wound healing property of NS/Gel were evaluated on the infected deep second-degree burn wound mice model.

Results

The mortality ratio of mice was concentration-dependent, and the LD₅₀ for silver sulfadiazine nanosuspension was estimated to be 252.1 mg/kg (230.8 to 275.4 mg/kg, 95% confidence limit). The in vivo dosages used for burn wound treatment (40-50 mg/kg) were far below LD₅₀ (252.1 mg/kg). NS/Gel significantly accelerated wound healing in the deep second wound infection mice model, achieving > 85% wound contraction on day 14. Staphylococcus aureus in the wound region was eradicated after 7 days in NS/Gel group, while the bacterial colony count was still measurable in the control group. Histological analysis and cytokines measurement confirmed that the mice treated with NS/Gel exhibited well-organized epithelium and multiple keratinized cell layers compared to control groups with the modulated expression of IL-6, VEGF, and TGF-β.

Conclusion

The combination of silver sulfadiazine nanosuspension and thermo-responsive hydrogel has great potential in clinical burn wound treatment.

Silver Nanoparticle Incorporated Human Amniotic Membrane Gel Accelerates Second-Degree Burn Wound Healing in Wister Rat

Burn has terrible consequences for the affected patients, making them vulnerable to wound infections and septicemia, which results in physical and mental disability and death, necessitating superior treatment options. Human amniotic membrane (HAM) has been utilized in burn wounds for decades for its low immunogenicity, angiogenic, anti-inflammatory, and antimicrobial properties and for promoting epithelialization. Silver nanoparticles (AgNPs), on the other hand, have antimicrobial properties and promote fibroblast migration. This study aimed to determine the burn wound healing potential of HAM + AgNPs. The gel was prepared using HAM (1% and 2%), AgNPs, carbopol 934, acrylic acid, glycerine, and triethanolamine, and different physical properties (pH, water absorption, swelling variation, spreadability, etc.) of the gel were determined; nuclear magnetic resonance (NMR) spectroscopy, antibacterial activity, brine shrimp lethality test, and histopathological observation were conducted. In vivo studies with Wistar rats demonstrated better healing capabilities than individual components of the gel. Wound contraction percentage after 20 days was 96.1 ± 0.27% which was highly significant (p < 0.0001), and the epithelialization period was 23.67 ± 2.05 days (p < 0.01) for HAM + AgNPs which was preferable to the positive control, AgNPs, HAM, and negative control; also, the histopathologic observation using hematoxylin and eosin, and Masson's trichrome staining were showed the better healing progress for HAM + AgNPs. Both HAM and AgNPs had antibacterial activities against gram-positive and gram-negative bacteria. These results indicated that the formulated HAM + AgNPs gel had remarkable effectiveness in burn wound healing compared to others. Further studies will be conducted to determine the molecular mechanism behind wound healing.

Scutellaria baicalensis Georgi regulates REV-ERBα/BMAL1 to protect against skin aging in mice

Scutellaria baicalensis Georgi (SBG) is a traditional Chinese medicine widely used to treat disorders such as hypertension, dysentery and hemorrhaging. Here, we aimed to assess the pharmacological effects of SBG on skin aging and to investigate the underlying mechanisms. Mice with skin aging were established by treatment with D-galactose and ultraviolet-B. SBG (topical application) showed a protective effect on skin aging in mice, as evidenced by less formation of skin wrinkles, higher levels of SOD (superoxide dismutase) and HYP (hydroxyproline) as well as a lower level of MDA (malondialdehyde). In the meantime, skin MMP-1 and p53 expression were lower, epidermis was thinner and collagen amount was higher in SBG-treated mice. Anti-skin aging effects of SBG were also confirmed in NIH3T3 and HaCaT cells, as well as in mouse primary dermal fibroblasts and human primary epidermal keratinocytes. Furthermore, we found that loss of Rev-erbα (a known repressor of Bmal1) up-regulated skin BMAL1 (a clock component and a known anti-aging factor) and ameliorated skin aging in mice. Moreover, SBG dose-dependently increased the expression of BMAL1 in the skin of aged mice and in senescent NIT3H3 cells. In addition, based on a combination of Gal4 chimeric, luciferase reporter and expression assays, SBG was identified as an antagonist of REV-ERBα and thus an inducer of BMAL1 expression. In conclusion, SBG antagonizes REV-ERBα to up-regulate BMAL1 and to protect against skin aging in mice.

Metronidazole Topically Immobilized Electrospun Nanofibrous Scaffold: Novel Secondary Intention Wound Healing Accelerator

The process of secondary intention wound healing includes long repair and healing time. Electrospun nanofibrous scaffolds have shown potential for wound dressing. Biopolymers have gained much attention due to their remarkable characteristics such as biodegradability, biocompatibility, non-immunogenicity and nontoxicity. This study anticipated to develop a new composite metronidazole (MTZ) immobilized nanofibrous scaffold based on poly (3-hydroxy butyrate) (PHB) and Gelatin (Gel) to be utilized as a novel secondary intention wound healing accelerator. Herein, PHB and Gel were mixed together at different weight ratios to prepare polymer solutions with final concentration of (7%), loaded with two different concentrations 5% (Z₁) and 10% (Z₂) of MTZ. Nanofibrous scaffolds were obtained by manipulating electrospinning technique. The properties of MTZ immobilized PHB/Gel nanofibrous scaffold were evaluated (SEM, FTIR, TGA, water uptake, contact angle, porosity, mechanical properties and antibacterial activity). Additionally, in vitro cytocompatibility of the obtained nanofibrous scaffolds were assessed by using the cell counting kit-8 (CCK-8 assay). Moreover, in vivo wound healing experiments revealed that the prepared nanofibrous scaffold highly augmented the transforming growth factor (TGF-β) signaling pathway, moderately suppressed the pro-inflammatory cytokine (IL-6). These results indicate that MTZ immobilized PHB/Gel nanofibrous scaffold significantly boost accelerating secondary intention wound healing.

Promotion of Burn Wound Healing by Local Application of Adipose-Derived Mesenchymal Stem Cells: An Experimental Study

Background:The burn wound is one of the health problems in the world that affects physical and mental health. Today, adipose-derived mesenchymal stem cells (ADSCs) have received medical attention for their accessibility and the ability to reproduce and repair. The present study was designed to investigate the effect of ADSCs on burn wound healing. Methods : The present experimental study was performed on 36 male Wistar rats divided into 1 control group and 3 experimental groups. The second-degree burns with a radius of 10 mm were induced after anesthesia. ADSCs and Dulbecco's Modified Eagle Medium (DMEM) were injected into the dermis around the burn area in the ADSCs and DMEM groups, respectively. Silver sulfadiazine (SSD) ointment was applied topically once daily as the SSD group. The control group did not receive any treatment. The rats were evaluated for 21 days. Wound healing rate, histopathological parameters, and the number of fibroblasts were evaluated by the immunofluorescence technique and vascular endothelial growth factor and transforming growth factor β (TGF-β) gene expression by reverse transcription-polymerase chain reaction. The results were entered into SPSS software (SPSS Inc) and analyzed with 1-way analysis of variance and repeated measures analysis. Results: The number of fibroblasts, the number of vessels, TGF-β, and VEGF gene expression in the burn area were significantly higher in the ADSCs group than in the SSD, DMEM, and control groups. The results also showed that the amount of inflammation was significantly lower in the ADSCs group compared with the control group (p<0.001). Moreover, the percentage of wound recovery was significantly higher in the ADSCs group compared with other groups (p<0.001). Conclusion: ADSCs accelerate and improve burn wound healing by affecting fibroblasts, keratinocytes, and inflammatory cells as well as increasing the expression of the TGF-β and VEGF genes, and thus increase in angiogenesis.

Characterization and cytotoxicity of low-molecular-weight chitosan and chito-oligosaccharides derived from tilapia fish scales

The present study evaluated the physicochemical characterization and cytotoxicity activity of chitosan and chito-oligosaccharides (COSs). The extraction of chitosan and COSs was executed by chemical hydrolysis. The physicochemical characterization and deacetylation (DA) value were determined using an FTIR. The molecular weight was determined by using the Mark-Houwink equation. The physical parameters such as solubility, water-binding capacity (WBC), and fat-binding capacity (FBC) were determination as per equation (i), (ii), and (iii) respectively. The cytotoxic activities of chitosan and COS against MCF-7, HepG2, HeLa-6, and 3T3 were performed by MTS assay. The COS induced enhance cytotoxicity with IC50 0.87 and2.21 mg/ml against MCF-7 and HepG2 respectively. However, COSs seem to be more sensitive toward the cell lines with the relative potential of MCF-7 > HepG2 > HeLa. Hence, the results showed promising future perspectives of chitosan and COS to develop biodegradable, antibacterial, cytotoxic naturally derived polysaccharides for cancer drug delivery and smart wound dressings.

The Efficacy of Silver-Based Electrospun Antimicrobial Dressing in Accelerating the Regeneration of Partial Thickness Burn Wounds Using a Porcine Model

(1) Background: Wounds with damages to the subcutaneous are difficult to regenerate because of the tissue damages and complications such as bacterial infection. (2) Methods: In this study, we created burn wounds on pigs and investigated the efficacy of three biomaterials: polycaprolactone-gelatin-silver membrane (PCLGelAg) and two commercial burn dressings, Aquacel^® Ag and UrgoTul^TM silver sulfadiazine. In vitro long-term antibacterial property and in vivo wound healing performance were investigated. Agar diffusion assays were employed to evaluate bacterial inhibition at different time intervals. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assays were used to compare antibacterial strength among samples. Second-degree burn wounds in the pig model were designed to evaluate the efficiency of all dressings in supporting the wound healing process. (3) Results: The results showed that PCLGelAg membrane was the most effective in killing both Gram-positive and Gram-negative bacteria bacteria with the lowest MBC value. All three dressings (PCLGelAg, Aquacel, and UrgoTul) exhibited bactericidal effect during the first 24 h, supported wound healing as well as prevented infection and inflammation. (4) Conclusions: The results suggest that the PCLGelAg membrane is a practical solution for the treatment of severe burn injury and other infection-related skin complications.

Fabrication of Hybrid Nanofibers from Biopolymers and Poly (Vinyl Alcohol)/Poly (ε-Caprolactone) for Wound Dressing Applications

The management of chronic wounds is challenging. The factors that impede wound healing include malnutrition, diseases (such as diabetes, cancer), and bacterial infection. Most of the presently utilized wound dressing materials suffer from severe limitations, including poor antibacterial and mechanical properties. Wound dressings formulated from the combination of biopolymers and synthetic polymers (i.e., poly (vinyl alcohol) or poly (ε-caprolactone) display interesting properties, including good biocompatibility, improved biodegradation, good mechanical properties and antimicrobial effects, promote tissue regeneration, etc. Formulation of these wound dressings via electrospinning technique is cost-effective, useful for uniform and continuous nanofibers with controllable pore structure, high porosity, excellent swelling capacity, good gaseous exchange, excellent cellular adhesion, and show a good capability to provide moisture and warmth environment for the accelerated wound healing process. Based on the above-mentioned outstanding properties of nanofibers and the unique properties of hybrid wound dressings prepared from poly (vinyl alcohol) and poly (ε-caprolactone), this review reports the in vitro and in vivo outcomes of the reported hybrid nanofibers.

Comparative assessment of the bactericidal effect of nanoparticles of copper oxide, silver, and chitosan-silver against Escherichia coli infection in broilers

Escherichia coli infection is considered one of the most economically important multi-systemic diseases in poultry farms. Several nanoparticles such as silver, chitosan, and copper oxide are known to be highly toxic to several microbes. However, there are no data concerning their success against in vivo experimental E. coli infection in broilers. Therefore, the present study was designed to investigate the bactericidal effect of low doses of CuO-NPs (5 mg/kg bwt), Ag-NPs (0.5 mg/kg bwt), and Ch-Ag NPs (0.5 mg/kg bwt) against E. coli experimental infection in broilers. One hundred chicks were divided into five groups as follows: (1) control; (2) E. coli (4 × 108 CFU/ml) challenged; (3) E. coli +CuO-NPs; (4) E. coli +Ag-NPs; (5) E. coli +Ch-Ag NPs. The challenged untreated group, not NPs treated groups, recorded the lowest weight gain as well as the highest bacterial count and lesion score in all examined organs. The highest liver content of silver was observed in Ag-NPs treated group compared with the Ch-Ag NPs treated group. Our results concluded that Ch-Ag NPs not only had the best antibacterial effects but also acted as a growth promoter in broilers without leaving any residues in edible organs. We recommend using Ch-Ag NPs in broiler farms instead of antibiotics or probiotics.

Autocrine and Paracrine Effects of Vascular Endothelial Cells Promote Cutaneous Wound Healing

Background

When vascular endothelial cells are subjected to external stimuli, paracrine hormones and cytokines act on adjacent cells. The regulation of the biological behaviour of cells is closely related to the maintenance of organ function and the occurrence and development of disease. However, it is unclear whether vascular endothelial cells affect the biological behaviour of cells involved in wound repair through autocrine and paracrine mechanisms and ultimately play a role in wound healing. We aimed to verify the effect of the autocrine and paracrine functions of vascular endothelial cells on wound healing.

Materials and Methods

ELISA was used to detect platelet-derived growth factor, basic fibroblast growth factor, epidermal growth factor, and vascular endothelial growth factor in human umbilical vascular endothelial cell-conditioned medium (HUVEC-CM). Different concentrations of HUVEC-CM were used to treat different stem cells. CCK-8 and scratch assays were used to detect the proliferation and migration ability of each cell. A full-thickness dorsal skin defect model was established in mice, and skin wound healing was observed after the local injection of HUVEC-CM, endothelial cell medium (ECM), or normal saline. H&E staining and immunofluorescence were used to observe the gross morphology of the wound tissue, the epithelial cell migration distance, and the expression of CD3 and CD31.

Results

HUVEC-CM promotes the proliferation and migration of epidermal stem cells, skin fibroblasts, bone marrow mesenchymal stem cells, and HUVECs themselves. Furthermore, HUVEC-CM can promote angiogenesis in mouse skin wounds and granulation tissue formation and can accelerate wound surface epithelialization and collagen synthesis, thereby promoting wound healing.

Conclusion

Our results clearly suggest that it is practicable and effective to promote wound healing with cytokines secreted by vascular endothelial cells in a mouse model.

Chitin and Chitosan Derivatives as Biomaterial Resources for Biological and Biomedical Applications

Chitin is a long-chain polymer of N-acetyl-glucosamine, which is regularly found in the exoskeleton of arthropods including insects, shellfish and the cell wall of fungi. It has been known that chitin can be used for biological and biomedical applications, especially as a biomaterial for tissue repairing, encapsulating drug for drug delivery. However, chitin has been postulated as an inducer of proinflammatory cytokines and certain diseases including asthma. Likewise, chitosan, a long-chain polymer of N-acetyl-glucosamine and d-glucosamine derived from chitin deacetylation, and chitosan oligosaccharide, a short chain polymer, have been known for their potential therapeutic effects, including anti-inflammatory, antioxidant, antidiarrheal, and anti-Alzheimer effects. This review summarizes potential utilization and limitation of chitin, chitosan and chitosan oligosaccharide in a variety of diseases. Furthermore, future direction of research and development of chitin, chitosan, and chitosan oligosaccharide for biomedical applications is discussed.

Research Advances in Chitosan Oligosaccharides: From Multiple Biological Activities to Clinical Applications

Chitosan oligosaccharides (COS), hydrolysed products of chitosan, are low-molecular weight polymers with a positive charge and good biocompatibility. COS have recently been reported to possess various biological activities, including hypoglycaemic, hypolipidaemic, antioxidantantioxidant, immune regulation, anti-inflammatory, antitumour, antibacterial, and tissue engineering activities, exhibiting extensive application prospects. Currently, the biological processes and mechanisms of COS are attractive topics of study, ranging from the genetic, molecular and protein levels. This article reviews the recent discoveries about COS, especially in metabolic regulation, immune function and tissue repair, providing important insights into their multiple biological activities, medical benefits, and therapeutic mechanisms.

Polyphenol-Conjugated Bimetallic Au@AgNPs for Improved Wound Healing

Background

Polyphenols possess antioxidant, anti-inflammatory and antimicrobial properties and have been used in the treatment of skin wounds and burns. We previously showed that tannic acid-modified AgNPs sized >26 nm promote wound healing, while tannic acid-modified AgNPs sized 13 nm can elicit strong local inflammatory response. In this study, we tested bimetallic Au@AgNPs sized 30 nm modified with selected flavonoid and non-flavonoid compounds for wound healing applications.

Methods

Bimetallic Au@AgNPs were obtained by growing an Ag layer on AuNPs and further modified with selected polyphenols. After toxicity tests and in vitro scratch assay in HaCaT cells, modified lymph node assay as well as the mouse splint wound model were further used to access the wound healing potential of selected non-toxic modifications.

Results

Tannic acid, gallic acid, polydatin, resveratrol, catechin, epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate and procyanidin B2 used to modify Au@AgNPs exhibited good toxicological profiles in HaCaT cells. Au@AgNPs modified with 15 μM tannic acid, 200 μM resveratrol, 200 μM epicatechin gallate, 1000 μM gallic acid and 200 μM procyanidin B2 induced wound healing in vivo and did not lead to the local irritation or inflammation. Tannic acid-modified Au@AgNPs induced epithelial-to-mesenchymal transition (EMT) - like re-epithelialization, while other polyphenol modifications of Au@AgNPs acted through proliferation and wound closure.

Conclusion

Bimetallic Au@AgNPs can be used as a basis for modification with selected polyphenols for topical uses. In addition, we have demonstrated that particular polyphenols used to modify bimetallic nanoparticles may show different effects upon different stages of wound healing.

Characterization and biological evaluation of a novel silver nanoparticle-loaded collagen-chitosan dressing

Effective coverage and protection is a priority in wound treatment. Collagen and chitosan have been widely used for wound dressings due to their excellent biological activity and biocompatibility. Silver nanoparticles (AgNPs) have a powerful antibacterial effect. In this study, a macromolecular and small-molecular collagen mixed solution, a macromolecular and small-molecular chitosan mixed solution were prepared, and a silver nanoparticle-loaded collagen-chitosan dressing (AgNP-CCD) has been proposed. First, the effects of a collagen-chitosan mixed solution on the proliferation of human umbilical vein endothelial cells and the secretion of cytokines were evaluated. Then, the characteristics and antibacterial effects of the AgNP-CCD were tested, and the effects on wound healing and the influence of wound cytokine expression were investigated via a deep second-degree burn wound model. The results showed that at the proper proportion and concentration, the collagen-chitosan mixed solution effectively promoted cell proliferation and regulated the levels of growth factors (vascular endothelial growth factor [VEGF], epidermal growth factor [EGF], platelet-derived growth factor [PDGF], transforming growth factor [TGF-β1], basic fibroblastic growth factor [bFGF]) and inflammatory factors (TNF-α, IL-1β, IL-6, IL-8). Moreover, AgNP solutions at lower concentrations exerted limited inhibitory effects on cell proliferation and had no effect on cytokine secretion. The AgNP-CCD demonstrated satisfactory morphological and physical properties as well as efficient antibacterial activities. An in vivo evaluation indicated that AgNP-CCD could accelerate the healing process of deep second-degree burn wounds and played an important role in the regulation of growth and inflammatory factors, including VEGF, EGFL-7, TGF-β1, bFGF, TNF-α and IL-1β. This AgNP-CCD exerted excellent biological effects on wound healing promotion and cytokine expression regulation.

Effect of Polysaccharides from Bletilla striata on the Healing of Dermal Wounds in Mice

Bletilla striata has been largely used in traditional folk medicine in China as a wound healing agent and to treat gastritis and several other health problems. Some studies have shown that plant polysaccharides may have the ability to promote wound healing. The aim of this work was to evaluate the wound healing activity of the polysaccharide extracted from Bletilla striata. Firstly, a Bletilla striata polysaccharide was extracted by water extraction and alcohol precipitation and characterized by Fourier transform infrared spectroscopy. The Bletilla striata polysaccharide was then tested for cell migration and proliferation using the mouse fibroblast cell line. Then, the Bletilla striata hydrogel was fabricated for acute wound health care of the mouse full-thickness excision. The results showed that the BSP enhanced the proliferation and migration of L929 cells. The superior wound healing capacity of the BSP hydrogel was demonstrated that it significantly accelerated the wound healing process in vivo in full-thickness skin defect wounded models. Compared to the saline group, the BSP hydrogel could accelerate wound healing and promote re-epithelialization and collagen deposition by means of TGF-β/Smad signal pathway activation. Taken together, BSP hydrogel would be a useful pharmaceutic candidate for acute cutaneous wound health care.

Toxicopathological and immunological studies on different concentrations of chitosan-coated silver nanoparticles in rats

Background

Much consideration has been paid to the toxicological assessment of nanoparticles prior to clinical and biological applications. While in vitro studies have been expanding continually, in vivo investigations of nanoparticles have not developed a cohesive structure. This study aimed to assess the acute toxicity of different concentrations of chitosan-coated silver nanoparticles (Ch-AgNPs) in main organs, including liver, kidneys, and spleen.

Materials and methods

Twenty-eight male albino rats were used and divided into 4 groups (n=7). Group 1 was kept as a negative control group. Groups 2, 3, and 4 were treated intraperitoneally with Ch-AgNPs each day for 14 days at doses of 50, 25, and 10 mg/kg body weight (bwt) respectively. Histopathological, morphometric and immunohistochemical studies were performed as well as oxidative stress evaluations, and specific functional examinations for each organ were elucidated.

Results

It was revealed that Ch-AgNPs induced dose-dependent toxicity, and the repeated dosing of rats with 50 mg/kg Ch-AgNPs induced severe toxicities. Histopathological examination showed congestion, hemorrhage, cellular degeneration, apoptosis and necrosis in hepatic and renal tissue as well as lymphocytic depletion with increasing tangible macrophages in the spleen. The highest levels of malondialdehyde, alanine aminotransferase, aspartate aminotransferase (MDA, ALT, AST) and the lowest levels of reduced glutathione, immunoglobulin G, M and total protein (GSH, IgG, IgM, TP) were observed in this group. On the other hand, repeated dosing with 25 mg/kg induced mild to moderate disturbance in the previous parameters, while there was no significant difference in results of pathological examination and biochemical tests between the control group and those treated with 10 mg/kg bwt Ch-AgNPs.

Conclusion

Chitosan-coated silver nanoparticles induce dose-dependent adverse effects on rats.

A Review of the Preparation, Analysis and Biological Functions of Chitooligosaccharide

Chitooligosaccharide (COS), which is acknowledged for possessing multiple functions, is a kind of low-molecular-weight polymer prepared by degrading chitosan via enzymatic, chemical methods, etc. COS has comprehensive applications in various fields including food, agriculture, pharmacy, clinical therapy, and environmental industries. Besides having excellent properties such as biodegradability, biocompatibility, adsorptive abilities and non-toxicity like chitin and chitosan, COS has better solubility. In addition, COS has strong biological functions including anti-inflammatory, antitumor, immunomodulatory, neuroprotective effects, etc. The present paper has summarized the preparation methods, analytical techniques and biological functions to provide an overall understanding of the application of COS.

Tannic acid-modified silver nanoparticles for wound healing: the importance of size

Introduction

Silver nanoparticles (AgNPs) have been shown to promote wound healing and to exhibit antimicrobial properties against a broad range of bacteria. In our previous study, we prepared tannic acid (TA)-modified AgNPs showing a good toxicological profile and immunomodulatory properties useful for potential dermal applications.

Methods

In this study, in vitro scratch assay, antimicrobial tests, modified lymph node assay as well as a mouse splint wound model were used to access the wound healing potential of TA-modified and unmodified AgNPs.

Results

TA-modified but not unmodified AgNPs exhibited effective antibacterial activity against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli and stimulated migration of keratinocytes in vitro. The tests using the mouse splint wound model showed that TA-modified 33 and 46 nm AgNPs promoted better wound closure, epithelialization, angiogenesis and formation of the granulation tissue. Additionally, AgNPs elicited expression of VEGF-α, PDGF-β and TGF-β1 cytokines involved in wound healing more efficiently in comparison to control and TA-treated wounds. However, both the lymph node assay and the wound model showed that TA-modified AgNPs sized 13 nm can elicit strong inflammatory response not only during wound healing but also when applied to the damaged skin.

Conclusion

TA-modified AgNPs sized >26 nm promote wound healing better than TA-modified or unmodified AgNPs. These findings suggest that TA-modified AgNPs sized >26 nm may have a promising application in wound management.

Chitosan oligosaccharide ameliorates acute lung injury induced by blast injury through the DDAH1/ADMA pathway

Objective

To investigate the protective effect of chitosan oligosaccharide (COS) on acute lung injury (ALI) caused by blast injury, and explore possible molecular mechanisms.

Methods

A mouse model of blast injury-induced ALI was established using a self-made explosive device. Thirty mice were randomly assigned to control, ALI and ALI + COS groups. An eight-channel physiological monitor was used to determine the mouse physiological index. Enzyme linked immunosorbent assay was used to measure serum inflammatory factors. Hematoxylin-eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, immunofluorescence staining, real time-polymerase chain reaction and western blot assay were used to detect inflammatory reactions, oxidative stress and apoptosis.

Results

Mice were sacrificed 24 hours after successful model induction. Compared with the ALI group, the heart rate, respiration and PCO₂ were significantly lower, but the PO₂, TCO₂ and HCO₃^- were significantly higher in the ALI + COS group. Compared to ALI alone, COS treatment of ALI caused a significant decrease in the wet/dry lung weight ratio, indicating a reduction in lung edema, inflammatory cell infiltration, levels of tumor necrosis factor-α, interleukin (IL)-1β, IL-4, IL-6 and nuclear factor kappa B mRNA and protein expression were reduced and IL-10 mRNA and protein expression was increased (P < 0.05). COS significantly inhibited reactive oxygen species, MDA5 and IREα mRNA and protein expressions, cell apoptosis and Bax and Caspase-3 mRNA and protein expressions, and significantly increased superoxide dismutase-1 mRNA expression, and Bcl-2 and Caspase-8 mRNA and protein expression (all P<0.05). COS significantly increased dimethylarginine dimethylaminohydrolase 1 (DDAH1) protein expression, and reduced ADMA and p38 protein expression (P< 0.05).

Conclusion

Blast injury causes inflammation, oxidative stress and apoptosis in the lung tissues of mice. COS has protective effects on blast injury-induced ALI, possibly by promoting DDAH1 expression and inhibiting ADMA and mitogen-activated protein kinase pathways.

Biodegradable elastic nanofibrous platforms with integrated flexible heaters for on-demand drug delivery

Delivery of drugs with controlled temporal profiles is essential for wound treatment and regenerative medicine applications. For example, bacterial infection is a key challenge in the treatment of chronic and deep wounds. Current treatment strategies are based on systemic administration of high doses of antibiotics, which result in side effects and drug resistance. On-demand delivery of drugs with controlled temporal profile is highly desirable. Here, we have developed thermally controllable, antibiotic-releasing nanofibrous sheets. Poly(glycerol sebacate)- poly(caprolactone) (PGS-PCL) blends were electrospun to form elastic polymeric sheets with fiber diameters ranging from 350 to 1100 nm and substrates with a tensile modulus of approximately 4-8 MPa. A bioresorbable metallic heater was patterned directly on the nanofibrous substrate for applying thermal stimulation to release antibiotics on-demand. In vitro studies confirmed the platform’s biocompatibility and biodegradability. The released antibiotics were potent against tested bacterial strains. These results may pave the path toward developing electronically controllable wound dressings that can deliver drugs with desired temporal patterns.

Nanomaterials in the Context of Type 2 Immune Responses-Fears and Potentials

The type 2 immune response is an adaptive immune program involved in defense against parasites, detoxification, and wound healing, but is predominantly known for its pathophysiological effects, manifesting as allergic disease. Engineered nanoparticles (NPs) are non-self entities that, to our knowledge, do not stimulate detrimental type 2 responses directly, but have the potential to modulate ongoing reactions in various ways, including the delivery of substances aiming at providing a therapeutic benefit. We review, here, the state of knowledge concerning the interaction of NPs with type 2 immune responses and highlight their potential as a multifunctional platform for therapeutic intervention.

Low molecular weight chitosan-coated silver nanoparticles are effective for the treatment of MRSA-infected wounds

Silver nanoparticles (AgNPs) are being widely applied as topical wound materials; however, accumulated deposition of silver in the liver, spleen, and other main organs may lead to organ damage and dysfunction. We report here that low molecular weight chitosan-coated silver nanoparticles (LMWC-AgNPs) are effective against methicillin-resistant Staphylococcus aureus (MRSA), have better biocompatibility, and have lower body absorption characteristics when compared with polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) and silver nanoparticles without surface stabilizer (uncoated-AgNPs) in a dorsal MRSA wound infection mouse model. LMWC-AgNPs were synthesized by reducing silver nitrate with low molecular weight chitosan as a stabilizer and reducing agent, while PVP-AgNPs were synthesized using polyvinylpyrrolidone as a stabilizer and ethanol as a reducing agent. AgNPs with different surface stabilizers were identified by UV-visible absorption spectrometry, and particle size was determined by transmission electron microscopy. UV-visible absorption spectra of LMWC-AgNPs, PVP-AgNPs and uncoated-AgNPs were similar and their sizes were in the range of 10–30 nm. In vitro experiments showed that the three types of AgNPs had similar MRSA-killing effects, with obvious effect at 4 μg/mL and 100% effect at 8 μg/mL. Bacteriostatic annulus experiments also showed that all the three types of AgNPs had similar antibacterial inhibitory effect at 10 μg/mL. Cell counting kit-8 assay and Hoechst/propidium iodide (PI) staining showed that LMWC-AgNPs were significantly less toxic to human fibroblasts than PVP-AgNPs and uncoated-AgNPs. Treatment of mice with MRSA wound infection demonstrated that the three types of AgNPs effectively controlled MRSA wound infection and promoted wound healing. After continuous application for 14 days, LMWC-AgNPs-treated mice showed significantly reduced liver dysfunction as demonstrated by the reduced alanine aminotransferase and aspartate aminotransferase levels and liver deposition of silver, in comparison to mice treated with uncoated-AgNPs or PVP-AgNPs. Our results demonstrated that LMWC-AgNPs had good anti-MRSA effects, while harboring a better biocompatibility and lowering the body’s absorption characteristics.

Surface Modification of Electrospun PVDF/PAN Nanofibrous Layers by Low Vacuum Plasma Treatment

Nanofibres are very promising for water remediation due to their high porosity and small pore size. Mechanical properties of nanofibres restrict the application of pressure needed water treatments. Various PAN, PVDF, and PVDF/PAN nanofibre layers were produced, and mechanical properties were improved via a lamination process. Low vacuum plasma treatment was applied for the surface modification of nanofibres. Atmospheric air was used to improve hydrophilicity while sulphur hexafluoride gas was used to improve hydrophobicity of membranes. Hydrophilic membranes showed higher affinity to attach plasma particles compared to hydrophobic membranes.