Silver Sulfadiazine Retards Wound Healing in Mice via Alterations in Cytokine Expression

Isoorientin Improves Excisional Skin Wound Healing in Mice

Background/Objectives: Wound healing relies on a coordinated process with the participation of different mediators. Natural products are a source of active compounds with healing potential. Isoorientin is a natural flavone recognized as having several pharmacological properties, such as anti-inflammatory effects, making it a potential treatment for wounds. We investigated the effect of isoorientin on the healing of excisional skin wounds. Methods: Male Swiss mice were subjected to the induction of excisional skin wounds (6 mm diameter) and treated with a vehicle (2% dimethyl sulfoxide in propylene glycol) or 2.5% isoorientin applied topically once a day for 14 days. The wound area was measured on days 0, 3, 7, and 14. Histopathological analyses were performed on the cicatricial tissue after 14 days. The myeloperoxidase activity and the interleukin-1β, tumoral necrosis factor (TNF)-α, and interleukin-6 concentrations were determined on the third day. Results: We observed that 3 days after the topical application of isoorientin, the lesion area was significantly smaller when compared to those of the vehicle (p < 0.01) and control (p < 0.05) groups. No difference was observed after 7 and 14 days of induction. Despite this, on day 14, histological analysis of cicatricial tissue from the animals treated with isoorientin showed reduced epidermal thickness (p < 0.001) and increased collagen deposition (p < 0.001). These effects were accompanied by decreased myeloperoxidase activity and interleukin-1β concentration on the third day of induction, without alteration in TNF-α and interleukin-6. Conclusions: The treatment with isoorientin promoted better tissue repair in excisional wounds in mice, which may be linked to the modulation of the early inflammatory response.

Commercial Silver-Based Dressings: In Vitro and Clinical Studies in Treatment of Chronic and Burn Wounds

Chronic wounds are a major health problem because of delayed healing, causing hardships for the patient. The infection present in these wounds plays a role in delayed wound healing. Silver wound dressings have been used for decades, beginning in the 1960s with silver sulfadiazine for infection prevention for burn wounds. Since that time, there has been a large number of commercial silver dressings that have obtained FDA clearance. In this review, we examine the literature involving in vitro and in vivo (both animal and human clinical) studies with commercial silver dressings and attempt to glean the important characteristics of these dressings in treating infected wounds. The primary presentation of the literature is in the form of detailed tables. The narrative part of the review focuses on the different types of silver dressings, including the supporting matrix, the release characteristics of the silver into the surroundings, and their toxicity. Though there are many clinical studies of chronic and burn wounds using silver dressings that we discuss, it is difficult to compare the performances of the dressings directly because of the differences in the study protocols. We conclude that silver dressings can assist in wound healing, although it is difficult to provide general treatment guidelines. From a wound dressing point of view, future studies will need to focus on new delivery systems for silver, as well as the type of matrix in which the silver is deposited. Clearly, adding other actives to enhance the antimicrobial activity, including the disruption of mature biofilms is of interest. From a clinical point of view, the focus needs to be on the wound healing characteristics, and thus randomized control trials will provide more confidence in the results. The application of different wound dressings for specific wounds needs to be clarified, along with the application protocols. It is most likely that no single silver-based dressing can be used for all wounds.

Xeroform Stick-Down Dressing: A Novel Treatment for Pediatric Partial-Thickness Burns

BACKGROUND

Burns traditionally require frequent, painful dressing changes to minimize infection risk and promote wound healing. To improve care for our pediatric population, our institution adapted a skin graft donor site dressing into a "stick-down" burn dressing consisting of a one-time application of bacitracin and 3% bismuth tribromophenate/vaseline impregnated gauze (Xeroform) that adheres to the burn and peels off as new epithelialized skin forms. The goal of which is to minimize dressing change frequency and patient discomfort in a cost-effective, widely available manner. This study aimed to compare clinical outcomes of the stick-down versus traditional topical dressings.

METHODS

A retrospective cohort study of pediatric patients (age <18 year) with partial-thickness burns treated at a level I pediatric trauma center for 4 years was conducted. One hundred eleven patients were included: 74 patients treated with daily silver sulfadiazene (Silvadene) dressings matched to 37 patients treated with the Xeroform stick-down dressing using 2:1 propensity score matching. Univariate analyses used Wilcoxon rank sum and Fisher exact tests.

RESULTS

The cohorts had similar demographics and burn characteristics. Both groups had similar hospitalization rates (31.1% Silvadene, 32.4% Xeroform), most commonly for pain control (54.5% Silvadene, 58.3% Xeroform), with similar average daily narcotic usage (7.7 ± 12.1 morphine milliequivalents Silvadene, 5.1 ± 9.5 Xeroform; P = 0.91). The Xeroform cohort had a shorter but statistically similar hospital stay (median, 1 vs 2 days). In addition, the Xeroform cohort required significantly less dressing changes with a median of 0.5 changes compared with 12 for the Silvadene cohort ( P < 0.0001). There was no difference in time to burn reepithelialization (median, 13.0 days for Silvadene and 12.0 days for Xeroform; P = 0.20) or wound healing complications (12.5% Silvadene, 2.7% Xeroform; P = 0.15).

CONCLUSIONS

The Xeroform stick-down dressing has equivalent clinical outcomes to that of standard Silvadene dressings for the treatment of pediatric partial-thickness burns with the major advantages of decreasing dressing change frequency, minimizing patient distress and pain, and streamlining clinical care.

The flower of Abelmoschus manihot (L.) medik exerts antioxidant effects by regulating the Nrf2 signalling pathway in scald injury

Scald is a common skin injury in daily life. It is well known that skin burns are associated with inflammation and oxidative stress. In our previous study, we found that Abelmoschus manihot (L.) medik had excellent therapeutic effects on scald-induced inflammation, but its effect on scald-induced oxidative stress was not reported. In this study, a deep second-degree scald model in mice was established, and the wound healing rate, healing time, malondialdehyde (MDA) and total superoxide dismutase (T-SOD) levels, and nuclear factor erythroid 2-related Factor 2 (Nrf2) expression in wound tissue were measured to evaluate the scald wound healing performance of extraction from A. manihot (L.) medik (EAM). Scalding activity in mice was examined in vivo by hot water-induced finger swelling. The treatment scald activities were also examined in vivo by subjecting mice to thermal water-induced digit swelling. Additionally, the antioxidant effect of EAM on fibroblasts was also used to determine the mechanism in vitro. The results showed that EAM not only decreased the wound healing time but also effectively regulated the levels of oxidising, MDA and T-SOD in wound tissue. Concurrently, EAM suppressed digit swelling and hyperalgesia. Furthermore, EAM had a significant protective effect on NIH-3T3 cells after H2 O2 injury by regulating the Nrf2 signalling pathway against oxidative injury. Therefore, EAM is a promising drug for the treatment of scald-induced inflammation.

Copper-based dressing: Efficacy in a wound infection of ex vivo human skin

This study aimed to evaluate the wound healing and antibacterial effects of two experimental copper dressings compared to a commercial silver dressing. Burn wounds were created in the ex vivo human skin biopsies, then were infected by Staphylococcus aureus. Tissues were treated with copper dressings, silver dressing, or a dressing without any antibacterial component. An infected wound tissue without treatment was considered as the control group. Three days after treatments, tissues were analyzed by bacterial count and histology staining, while their media was used to assess the expression of cytokines and chemokines. Histology staining confirmed the presence of second-degree burn wounds and colonization of bacteria in the surface and superficial layer of tissues. The results demonstrated a higher antibacterial effect, improved epithelium formation, and decreased wound area in one of the copper dressings compared to other dressings. Markers associated with infection control increased in both the copper and silver-treated groups. The cytokine profiling analysis revealed increased expression of markers related to angiogenesis and anti-inflammatory responses and decreased pro-inflammatory cytokine responses in the infected wound treated with one of the copper dressings. Our results confirmed the efficacy of the experimental copper dressing in reducing bacteria and promoting wound healing.

Clinical Evaluation of the Efficacy and Tolerability of Rigenase® and Polyhexanide (Fitostimoline® Plus) vs. Hyaluronic Acid and Silver Sulfadiazine (Connettivina® Bio Plus) for the Treatment of Acute Skin Wounds: A Randomized Trial

OBJECTIVES

Compare the efficacy and tolerability of Connettivina® Bio Plus (Group A) gauze and cream, and Fitostimoline® Plus (Group B) gauze and cream for the treatment of acute superficial skin lesions.

DESIGN

Single-center, parallel, randomized trial. A block randomization method was used.

SETTING

University of Salerno-AOU San Giovanni di Dio e Ruggi d'Aragona.

PARTICIPANTS

Sixty patients were enrolled. All patients fulfilled the study requirements.

INTERVENTION

One application of the study drugs every 24 h, and a six-week observation period.

MAIN OUTCOME MEASURES

Efficacy and tolerability of the study drugs.

RESULTS

In total, 60 patients (Group A, n = 30; Group B, n = 30) were randomized; mean age was 58.5 ± 15.8 years. All patients were included in the outcome analysis. Total wound healing was achieved in 17 patients undergoing treatment with Connettivina® Bio Plus and 28 patients undergoing treatment with Fitostimoline® Plus. The greater effectiveness of the latter was significant (p = 0.00104). In Group B, a significantly greater degree of effectiveness was observed in reducing the fibrin in the wound bed (p = 0.04746). Complications or unexpected events were not observed.

CONCLUSIONS

Both Connettivina® Bio Plus and Fitostimoline® Plus are secure and effective for treating acute superficial skin lesions. Fitostimoline® Plus was more effective than Connettivina® Bio Plus in wound healing of acute superficial skin lesions, especially if fibrin had been observed in the wound bed.

A Systematic Review: Topical Sucralfate for Burn Wound

BACKGROUND: Topical sucralfate has been used for burn and non-burn skin and mucosal lesion with remarkable results. The healing rate of mucosa is faster than skin lesion. AIM: A current systematic review was conducted to objectively evaluate wound healing benefits of topical sucralfate for burn wound and to show on which degree of burn wound it works compare with another topical agents of burn wound therapy. METHODS: Databases were searched for relevant studies: Google Scholar, PUBMED, and ProQuest. Data sources were searched using MeSH terms: “topical sucralfate” and “burn wound” for all publications up to December 2018. All English papers were included. Only studies performed in humans were included in this study. A total of 2437 publications were found, of which 3 studies met the inclusion criteria and were relevant to be used in this systematic review. The primary outcome was burn wound healing. DATA EXTRACTION: Data from retrieved studies were reviewed and tabulated according to year of publication, study design, human or animal studies, characteristics of the population, and outcomes. DATA SYNTHESIS: A total of 2 randomized controlled trials (RCTs) and 1 observational comparative study were found. All trials are on second degree burn wound patients. Jadad score was used to assess the methodological quality of the RCTs. One RCT and one comparative study demonstrated favorable outcomes with the use of topical sucralfate. There is one publication with no significant differences. CONCLUSIONS: This systematic review shows a noticeably beneficial effect of topical sucralfate for burn wound. It is better than other topical agent in wound healing rate, decreased infection rate and enhancement of epithelialization also granulation with no local or systemic adverse reactions. However, multicenter RCT with larger sample size are needed to make recommendation for burn wound treatment.

Silver distribution in chronic wounds and the healing dynamics of chronic wounds treated with dressings containing silver and octenidine

Although silver is an efficient antimicrobial and is a widely used antiseptic in wound healing, previous studies have reported the cytotoxic in vitro effects of silver dressings. Moreover, few studies have addressed the distribution of silver in chronic wounds. The study compares the healing of chronic wounds treated with a standard-of-care silver dressing (Ag-CMC) and a dressing containing antiseptic octenidine (OCT-HA). Biopsies were taken from two wound areas before the commencement of treatment (baseline), after 2 weeks and after 6 weeks (the end of the study). We analyzed the histopathologic wound-healing score, silver distribution, and expression of selected genes. The wound-healing score improved significantly in the wounded area treated with OCT-HA after 2 weeks compared to the baseline and the Ag-CMC. The Ag-CMC wound areas improved after 6 weeks compared to the baseline. Moreover, collagen maturation and decreases in the granulocyte and macrophage counts were faster in the OCT-HA parts. Treatment with OCT-HA resulted in less wound slough. The silver, visualized via autometallography, penetrated approximately 2 mm into the wound tissue and associated around capillaries and ECM fibers, and was detected in phagocytes. The metallothionein gene expression was elevated in the Ag-CMC wound parts. This exploratory study determined the penetration of silver into human chronic wounds and changes in the distribution thereof during treatment. We observed that silver directly affects the cells in the wound and elevates the metallothionein gene expression. Octenidine and hyaluronan dressings provide a suitable alternative to silver and carboxymethyl cellulose dressings without supplying silver to the wound.

Effect of Multiradiance Low-Level Laser Therapy and Topical Silver Sulfadiazine on Healing Characteristics of Dermal Wounds in Marine Toads (Rhinella marina)

Current recommendations for wound management in amphibians are based primarily on clinical experience and on extrapolation from other taxa, whereas controlled clinical studies are lacking. Low-level laser therapy, also termed photobiomodulation, has gained popularity in veterinary medicine and may represent a valuable adjunct therapy for wound care in amphibians, though dosing and safety evaluations have not been previously reported. Silver sulfadiazine (SSD), a topical antimicrobial, is commonly utilized in amphibian medicine but little is known about its effects on wound healing in this class of animals. This pilot study evaluated the effects of repeated treatments of low-level laser therapy or topical SSD on second-intention healing characteristics of surgically induced full-thickness dermal wounds in 33 adult wild-caught marine toads. Toads were anesthetized, and a 6 mm cutaneous biopsy was performed over the right dorsum. They were then randomly assigned to one of three groups: laser therapy (LT) at 5 Hz (905 nm wavelength on a super pulsed sequence), topical SSD (SD), or control sham treatment (CT). Treatments were administered at 24 hrs after biopsy and then every 72 hrs thereafter, concurrent with a visual assessment of the wound. Toads were euthanized at one of five timepoints (day 4, 7, 13, 19, or 28) to permit scoring of histologic criteria, including lymphocytic inflammation, granulomatous inflammation, heterophilic inflammation, granulation tissue, fibrosis, and reepithelialization. Visual assessments and histologic scoring did not identify a benefit of laser therapy or SSD as compared to controls. Laser therapy and SSD, at the doses and dosing schedule utilized in this pilot study, appear to be safe and well-tolerated treatments in marine toads, but may not be warranted for uncomplicated skin wounds in this species.

Effects of wound dressings containing silver on skin and immune cells

Wound dressings with silver have been shown to be cytotoxic in vitro. However, the extrapolation of this cytotoxicity to clinical settings is unclear. We applied dressings with various forms of silver on porcine skin ex vivo and investigated silver penetration and DNA damage. We assessed antimicrobial efficacy, cytotoxicity to skin cells, and immune response induced by the dressings. All dressings elevated the DNA damage marker γ-H₂AX and the expression of stress-related genes in explanted skin relative to control. This corresponded with the amount of silver in the skin. The dressings reduced viability, induced oxidative stress and DNA damage in skin cells, and induced the production of pro-inflammatory IL-6 by monocytes. The oxidative burst and viability of activated neutrophils decreased. The amount of silver released into the culture medium varied among the dressings and correlated with in vitro toxicity. However, antimicrobial efficiencies did not correlate strongly with the amount of silver released from the dressings. Antimicrobial efficiency and toxicity are driven by the form of silver and the construction of dressings and not only by the silver concentration. The damaging effects of silver dressings in ex vivo skin highlight the importance of thorough in vivo investigation of silver dressing toxicity.

Silver Sulfadiazine's Effect on Keratin-19 Expression as Stem Cell Marker in Burn Wound Healing

BACKGROUND

Burn wounds are one of the causes of cutaneous injury that involve both epidermal and dermal layers of skin. Silver sulfadiazine (SSD) has been widely used to treat burn wounds, however recent studies have found the treatment to have some drawbacks, such as cellular toxicity effects. Cutaneous wound regeneration is known to start from the basal layer of the epidermal epithelial cells, which are enriched with highly proliferative cells. Keratin-19 (K19) is one of the epidermal stem cell biomarkers found in the skin. This study aims to explore the expression of K19 in burn wound tissue and to investigate the effect of SSD on its expression.

METHODS

We created a burn wound model in Sprague Dawley rats and randomly divided them into control and SSD groups. Wound closure was evaluated (visitrak) overtime series followed by histological evaluation of K19 expression in the wound tissue (immunohistochemistry staining).

RESULTS

Our model successfully represents full-thickness damage caused by a burn wound. The SSD group showed a faster reduction of wound surface area (wound closure) compared to the control group with the peak at day 18 post wounding (p < 0.05). K19 expression was found in both groups and was distributed on epidermal layers, hair follicles and dermis of granulation tissue showing similar patterns.

CONCLUSION

Topical application of SSD on burn wounds showed superiority in wound closure and is likely to have no harmful effect on epidermal stem cells. However, further study is required to investigate the effect of silver species on cell viability and toxicity effects during long term treatment.

Ionic silver functionalized ovine forestomach matrix - a non-cytotoxic antimicrobial biomaterial for tissue regeneration applications

BACKGROUND

Antimicrobial technologies, including silver-containing medical devices, are increasingly utilized in clinical regimens to mitigate risks of microbial colonization. Silver-functionalized resorbable biomaterials for use in wound management and tissue regeneration applications have a narrow therapeutic index where antimicrobial effectiveness may be outweighed by adverse cytotoxicity. We examined the effects of ionic silver functionalization of an extracellular matrix (ECM) biomaterial derived from ovine forestomach (OFM-Ag) in terms of material properties, antimicrobial effectiveness and cytotoxicity profile.

METHODS

Material properties of OFM-Ag were assessed by via biochemical analysis, microscopy, atomic absorption spectroscopy (AAS) and differential scanning calorimetry. The silver release profile of OFM-Ag was profiled by AAS and antimicrobial effectiveness testing utilized to determine the minimum effective concentration of silver in OFM-Ag in addition to the antimicrobial spectrum and wear time. Biofilm prevention properties of OFM-Ag in comparison to silver containing collagen dressing materials was quantified via in vitro crystal violet assay using a polymicrobial model. Toxicity of ionic silver, OFM-Ag and silver containing collagen dressing materials was assessed toward mammalian fibroblasts using elution cytoxicity testing.

RESULTS

OFM-Ag retained the native ECM compositional and structural characteristic of non-silver functionalized ECM material while imparting broad spectrum antimicrobial effectiveness toward 11 clinically relevant microbial species including fungi and drug resistant strains, maintaining effectiveness over a wear time duration of 7-days. OFM-Ag demonstrated significant prevention of polymicrobial biofilm formation compared to non-antimicrobial and silver-containing collagen dressing materials. Where silver-containing collagen dressing materials exhibited cytotoxic effects toward mammalian fibroblasts, OFM-Ag was determined to be non-cytotoxic, silver elution studies indicated sustained retention of silver in OFM-Ag as a possible mechanism for the attenuated cytotoxicity.

CONCLUSIONS

This work demonstrates ECM biomaterials may be functionalized with silver to favourably shift the balance between detrimental cytotoxic potential and beneficial antimicrobial effects, while preserving the ECM structure and function of utility in tissue regeneration applications.

Silver Sulfadiazine Retards Wound Healing and Increases Hypertrophic Scarring in a Rabbit Ear Excisional Wound Model

This study evaluated the effects of topical use of silver sulfadiazine cream (SSD) on wound healing and subsequent scarring in a rabbit ear wound model. Seven millimeter full-thickness excisional wounds were created in rabbit ears. Twenty-four rabbits were randomized into four groups in which each group received base cream, 0.01% SSD, 0.1% SSD, or 1% SSD, respectively. Each treatment was applied at 2-day intervals from postoperative days (PODs) 2 to 14. At POD 7, half of the rabbits from each group were killed and tissues were harvested to measure wound healing parameters that included epithelial gap and granulation area. At POD 28, the remaining rabbits from each group were assessed for hypertrophic scarring. Epithelial gaps in SSD-treated groups at concentrations of 0.1 and 1% were significantly larger than those of base cream-treated controls. In contrast, analysis of granulation areas that represent volume of granulation tissue formed during healing did not show any statistical differences between the base cream-treated group and all three SSD-treated groups. At POD 28, when compared to the base cream-treated group (1.44 ± 0.03), SSD-treated-groups (0.1 and 1%) had more (P < .05) hypertrophic scar formation (scar elevation index = 1.65 ± 0.04, 0.1%; 1.63 ± 0.06, 1%). The results of this study demonstrate that SSD treatment contributes not only to impaired reepithelialization but also to a greater hypertrophic scar formation. These results also indicate that caution should be exercised when using SSD clinically to prevent or treat wound infections.

Antimicrobial ceragenins inhibit biofilms and affect mammalian cell viability and migration in vitro

The healing of burn wounds is often hampered by bacterial infection and the formation of biofilms. Antimicrobial peptides (AMPs) are effective in promoting wound healing, but are susceptible to degradation. We have tested the ability of ceragenins (CSAs), mimics of antimicrobial peptides, to mitigate preformed biofilms and stimulate wound healing in vitro. Potent CSAs (MICs < 10 μg·mL⁻¹) were tested against biofilms formed from a mixture of Pseudomonas aeruginosa and Staphylococcus aureus grown for 22 h and subjected to 20 h treatment. Many CSAs showed more potent anti‐biofilm activity than the endogenous AMP LL‐37, and CSA‐13 and CSA‐90 decreased the amount of biofilm matrix substances detected by SYPRO Ruby stain. Effects on mammalian cells were measured by viability, migration, and tube formation assays in vitro. Although CSAs were toxic to immortalized human keratinocytes (HaCaTs) at higher concentrations (>10 μg·mL⁻¹), lower concentrations of CSA‐13 and CSA‐192 stimulated cell migration. CSA‐13, CSA‐90, and CSA‐142 also stimulated tube formation in an in vitro angiogenesis model. An inhibitor of vascular endothelial growth factor receptor 2 (VEGFR2) blocked tube formation stimulated by CSA‐13, suggesting that CSA‐13 signals through this receptor. Ceragenins display anti‐biofilm activity and stimulate migration and tube formation in vitro. This work suggests that ceragenins have the potential to be both topical antimicrobials and wound‐healing adjunct therapeutics.

Using chitosan nanoparticles as drug carriers for the development of a silver sulfadiazine wound dressing

Burn wounds environment favors the growth of micro-organisms causing delay in wound healing. The traditional treatment with antimicrobial creams offer inaccurate doses. In the present study, a dressing coated with silver sulfadiazine (SSD) loaded chitosan nanoparticles (CSNPs) for the controlled-release of SSD into burn wound to control bacterial growth was investigated. CSNPs were formulated with different concentrations of chitosan and CM-β-CD and loaded with SSD complexed in 1:1 molar ratio with CM-β-CD, CSNPs were assessed for their particle size, polydispersity index, morphology and association efficiency. The formula showing the best characteristics was selected for the preparation of SSD loaded CSNPs wound dressing through a padding process with/without the use of cross-linker. The dressing was characterized for its physical properties, in addition, FTIR, X-ray, SEM and in vitro release were used for characterization. The dressing was proven effective for the inhibition of the growth of Gram positive and Gram negative bacteria as well as candida on an infected wound.