Translational application of human keratinocyte-fibroblast cell sheets for accelerated wound healing in a clinically relevant type 2 diabetic rat model.

BACKGROUND AIMS: Despite advancements in wound care, wound healing remains a challenge, especially in individuals with type 2 diabetes. Cell sheet technology has emerged as an efficient and promising therapy for tissue regeneration and wound repair. Among these, bilayered human keratinocyte-fibroblast cell sheets constructed using temperature-responsive culture surfaces have been shown to mimic a normal tissue-like structure and secrete essential cytokines and growth factors that regulate the wound healing process. METHODS: This study aimed to evaluate the safety and therapeutic potential of human skin cell sheets to treat full-thickness skin defects in a rat model of type 2 diabetes. RESULTS: Our findings demonstrate that diabetic wounds transplanted with bilayered cell sheets resulted in accelerated re-epithelialization, increased angiogenesis, enhanced macrophage polarization and regeneration of tissue that closely resembled healthy skin. In contrast, the control group that did not receive cell sheet transplantation presented characteristic symptoms of impaired and delayed wound healing associated with type 2 diabetes. CONCLUSIONS: The secretory cytokines and the upregulation of Nrf2 expression in response to cell sheet transplantation are believed to have played a key role in the improved wound healing observed in diabetic rats. Our study suggests that human keratinocyte-fibroblast cell sheets hold great potential as a therapeutic alternative for diabetic ulcers.

Expansion of fibroblast cell sheets using a modified MEEK micrografting technique for wound healing applications.

Cell sheet engineering, a scaffold-free approach to fabricate functional tissue constructs from several cell monolayers, has shown promise in tissue regeneration and wound healing. Unfortunately, these cell sheets are often too small to provide sufficient wound area coverage. In this study, we describe a process to enlarge cell sheets using MEEK micrografting, a technique extensively used to expand skin autografts for large burn treatments. Human dermal fibroblast cell sheets were placed on MEEK's prefolded gauze without any use of adhesive, cut along the premarked lines and stretched out at various expansion ratios (1:3, 1:6 and 1:9), resulting in regular distribution of many square islands of fibroblasts at a much larger surface area. The cellular processes essential for wound healing, including reattachment, proliferation, and migration, of the fibroblasts on expanded MEEK gauze were superior to those on nylon dressing which served as a control. The optimal expansion ratio with the highest migration rate was 1:6, possibly due to the activation of chemical signals caused by mechanical stretching and an effective intercellular communication distance. Therefore, the combination of cell sheet engineering with the MEEK micrografting technique could provide high quality cells with a large coverage area, which would be particularly beneficial in wound care applications.

Characteristics and Safety Profiles of a Hydrocolloid Polyester Dressing Incorporated with Herbal Extract: In Vitro, in Vivo and Randomized Clinical Studies.

The polyester dressing containing herbal extract had been used for several years. However, some properties had not been investigated. This study examined three parts including in vitro studies, skin irritation in an animal model, and the pilot clinical study in traumatic wounds. In in vitro studies, six different wound dressings consisted of hydrocolloid polyester containing herbal extract (SI-HERB®), hydrofiber (Aquacel®), hydrocolloid polyester (Urgotul®), soft paraffin gauze (Bactigras®), foam (Mepilex®), and biocellulose (Suprasorb® X + PHMB) dressings were comparatively evaluated in physical properties including the fluid absorption, desorption, and fluid drainage ability. The skin irritation test was examined in a rabbit model using SI-HERB® as a tested group. In a clinical study, traumatic patients with leg wounds were randomly assigned to six wound dressings. The primary outcome was the pain level and the secondary outcomes were non-adherence and peri-wound reaction evaluating score. From the study, Bactigras® had the largest pore size but the total area of pore size per field of it was similar to SI-HERB®. There were no significant differences between SI-HERB®, Urgotul®, and Bactigras® in the percentage of absorption and desorption. No dermatologic effect was found in the animal study. In the irritation test on leg wounds, pain level, and peri-wound reaction in hydrocolloid polyester dressing group were significantly lower compared with Aquacel® and Bactigras®. The polyester dressing had the pain level after removal lower than before application while the Mepilex® and Suprasorb® presented that insignificantly increase the pain level. Erythema could be observed in Bactigras®, Aquacel®, and Suprasorb® but the edema scores were not different. A hydrocolloid polyester dressing containing herbal extract had good drainage ability. No skin irritation was reported. Pain scores, removal ability, and peri-wound reaction were also significantly lower with other types of wound dressings. These results suggested that this dressing be an alternative in wound treatment.

Polyurethane-biomacromolecule combined foam dressing containing asiaticoside: fabrication, characterization and clinical efficacy for traumatic dermal wound treatment.

Polyurethane combined (PUC) foam dressings with various biomacromolecules were fabricated with the adsorption of asiaticoside and silver nanoparticles for traumatic wound treatment. Biomacromolecules had varying effects on physicochemical and mechanical properties of PU foam. With 2% incorporation, starches, high molecular weight chitosan and gelatin provided stiffer and more porous foams while carboxymethylcellulose had the highest compression strength but the lowest water vapor transmission. High water absorption was from foams with carboxymethylcellulose, alginate, hydroxypropyl methylcellulose and low molecular weight chitosan. Increasing the concentrations up to 12% had more prominent effect. However, powdery surface was noticed with poorer tensile properties that 6% incorporation was selected. FTIR spectra and DSC thermograms suggested interaction of PU formulation with biomacromolecules. EDS analysis confirmed existence of active compounds while acceptable stability was from sterilized PUC foam with alginate. On healthy volunteers, this selected foam dressing caused no skin irritation and retained moisture comparable to commercial product. In patients with traumatic dermal wounds, healing improvement with shorter wound closure time, higher reepithelialization and less pain score were from the selected foam dressing compared to standard gauze soaked with chlorhexidine. This PU-alginate combined foam dressing adsorbed with asiaticoside and silver nanoparticles proved advantages for traumatic dermal wound management.

Development of polyurethane foam dressing containing silver and asiaticoside for healing of dermal wound.

Polyurethane foam dressings for dermal wounds were formulated with natural polyols in order to improve the foam characteristics and the release of 2 active agents, silver and asiaticoside (AS) as an antimicrobial agent and an herbal wound healing agent, respectively. The foam was instantly formed by interaction of polyols and diisocyanate. Hydroxypropyl methylcellulose, chitosan and sodium alginate were individually mixed with the main polyols, polypropylene glycol, in the formulation while the active components were impregnated into the obtained foam dressing sheets. Although the type and amount of the natural polyols slightly affected the pore size, water sorption-desorption profile and compression strength of the obtained foam sheets, a prominent effect was found in the release of both active components. Among natural polyols formulations, foam sheets with alginate showed the highest silver and AS release. Non-cytotoxicity of these foam sheets to human fibroblast cells was confirmed. Antimicrobial testing on four bacteria strains showed that 1 mg/cm2 silver in formulations with 6% of natural polyols and without natural polyols had sufficient content of the silver release with comparable inhibition zone and significantly larger zone than other formulations. In pig study, the foam dressing with 6% alginate, 1 mg/cm2 silver and 5% AS could improve wound healing in both the percentage of the wound closure and histological parameters of the dermal wound without any dermatologic reactions. In conclusion, this innovative foam dressing had potential to be a good candidate for wound treatment.

Randomized Controlled Trial of Polyhexanide/Betaine Gel Versus Silver Sulfadiazine for Partial-Thickness Burn Treatment.

Silver sulfadiazine is commonly used in the treatment of partial-thickness burns, but it sometimes forms pseudo-eschar and delays wound healing. Polyhexanide/betaine gel, a new wound cleansing and moisturizing product, has some advantages in removing biofilm and promotes wound healing. This study was designed to compare clinical efficacy of polyhexanide/betaine gel with silver sulfadiazine in partial-thickness burn treatment. From September 2013 to May 2015, 46 adult patients with partial-thickness burn ≥10% total body surface area that were admitted to the Burn Unit of Siriraj Hospital within 48 hours after injury were randomly allocated into 2 groups. One group was treated with polyhexanide/betaine gel, and the other group was treated with silver sulfadiazine. Both groups received daily dressing changes and the same standard care given to patients with burns in this center. Healing times in the polyhexanide/betaine gel group and silver sulfadiazine group were 17.8 ± 2.2 days and 18.8 ± 2.1 days, respectively ( P value .13). There were no significant differences in healing times, infection rates, bacterial colonization rates, and treatment cost in both groups. The pain score of the polyhexanide/betaine gel group was significantly less than the silver sulfadiazine group at 4 to 9 days after treatment ( P < .001). The satisfactory assessment result of the polyhexanide/betaine gel group was better than that in the silver sulfadiazine group. These data indicate the need for adequately designed studies to elicit the full potential of polyhexanide gel as a wound dressing for partial-thickness burn wounds.

In vitro evaluation of the antimicrobial effectiveness and moisture binding properties of wound dressings.

A variety of silver-coated dressings and some impregnated with other chemicals are now available in the market; however, there have been few studies analyzing their comparative efficacies as antimicrobial agents. Moreover, their properties for retaining an appropriate level of moisture that is critical for effective wound healing have never been reported. Five commercially available silver-containing and chlorhexidine dressings, Urgotul SSD(®), Bactigras(®), Acticoat(®), Askina Calgitrol Ag(®) and Aquacel Ag(®), were tested to determine their comparative antimicrobial effectiveness in vitro against five common wound pathogens, namely methicillin-sensitive and -resistant Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. Mepitel(®), a flexible polyamide net coated with soft silicone, was used as a control. The zones of inhibition and both the rapidity and the extent of killing of these pathogens were evaluated. All five antimicrobial dressings investigated exerted some bactericidal activity, particularly against E. coli. The spectrum and rapidity of action ranged widely for the different dressings. Acticoat(®) had a broad spectrum of action against both Gram-positive and -negative bacteria. Other dressings demonstrated a narrower range of bactericidal activities. Regarding the absorption and release of moisture, Askina Calgitrol Ag(®) absorbed and released the most moisture from the environment. Aquacel Ag(®) also exhibited good moisture absorption and moisture release, but to a lower degree. The other tested dressings absorbed or released very little moisture. Askina Calgitrol Ag(®) and Aquacel Ag(®) are good alternative dressings for treating wounds with high exudates and pus. An understanding of the characteristics of these dressings will be useful for utilizing them for specific requirements under specified conditions.

Clinical effectiveness of alginate silver dressing in outpatient management of partial-thickness burns.

Askina Calgitrol Ag(®) (B. Braun Hospicare Ltd, Collooney Co. Sligo, Ireland), alginate silver wound dressing, is an advanced wound dressing which combines the potent broad-spectrum antimicrobial action of silver with enhanced exudate management properties of calcium alginate and polyurethane foam. The purpose of this study was to compare the efficacy of Askina Calgitrol Ag(®) and 1% silver sulfadiazine (1% AgSD) in the outpatient management of partial-thickness burn wounds at Burn Unit, Siriraj Hospital. A prospective descriptive study was conducted between January 2008 and January 2009 in Burn Unit, Division of Trauma Surgery, Siriraj Hospital, Mahidol University, Thailand. The 65 patients with partial-thickness burn wounds, less than 24 hours post-burn injury, had a total body surface area (TBSA%) less than 15% were treated at Siriraj Outpatient Burn Clinic. All patients were divided into Askina Calgitrol Ag(®) treated group (30 patients) and 1% AgSD treated group (35 patients). The data were compared by the demographics including age, gender, % TBSA burn, pain score, number of wound dressing change, nursing time and time of wound healing. Patients included in both groups were comparable with no significant differences in demographic data of age, gender, location of burn and type of burn injury (P > 0·05 evaluated by paired Student's t-test) between both group. The present results showed that average pain scores in the Askina Calgitrol Ag(®) treated group were significantly lower than the 1% AgSD treated group (2·23 ± 1·87 versus 6·08 ± 2·33, respectively) between both groups (P < 0·02). Patients treated with Askina Calgitrol Ag(®) had significantly lower number of wound dressing change (P < 0·02) and nursing time (P < 0·02) compared with 1% AgSD treated group. The Askina Calgitrol Ag(®) group needed less frequent wound dressing. Healing time was 7 ± 3·51 days after the application of Askina Calgitrol Ag(®). This was significantly shorter than that of control wounds (14 ± 4·18 days). Application of Askina Calgitrol Ag(®) leads to a good burn wound outcome. The present study confirms the effectiveness of Askina Calgitrol Ag(®) in the outpatient management of partial-thickness burn wounds.