Comparison of Glyaderm with different dermal substitute matrices in a porcine wound model.

Background: The closure of extensive burn wounds with widely expanded autologous split-thickness skin grafts (STSG) is associated with undesirable scar formation and contraction, due to the lack of dermis. Various materials for dermal replacement have been developed, either of xenogeneic, allogeneic or synthetic origin and are placed in the wound underneath a thin STSG in order to improve scar quality. In this study, a porcine wound model was used to compare several commercially available acellular dermal substitutes with an acellular dermal substitute prepared from glycerol preserved human skin: GlyadermⓇ. Methods: Antigenic components of the allografts were removed by incubation in the 0.06 M NaOH solution. In the first experiments, the dermal substitutes were applied to full thickness wounds and covered simultaneously with STSG. Controls were covered with STSG only. The wound healing response was analyzed for 8 weeks, both macroscopically and histologically. The Mann-Whitney U test was used for statistical analysis. In the second series of experiments, GlyadermⓇ was applied in a two-stage procedure in comparison to Integra. The STSG was placed on the dermal substitutes one week later. Results: In the first series, the inflammatory response and myofibroblast influx in GlyadermⓇ were limited, indicating possible beneficial outcomes on final wound healing results. The survival of the STSG on the acellular dermis was lower compared to the control wounds. Second series: the take of the STSG was the same as in the controls, but additionally wound contraction was reduced. The application of GlyadermⓇ was non-inferior to Integra. Conclusion: GlyadermⓇ can be successfully used for the reduction of wound contraction when applied in a two-stage procedure.

Silver Sulfadiazine Cream Treatment Results in More Wound Contraction and More Itch in a Standardized Porcine Scald Model.

A variety of dressings is available for the treatment of partial-thickness wounds, but none has strong evidence supporting their beneficial effect on healing. This may be due to variation in the type and depth of wounds in clinical studies. The aim of this study was to use a standardized porcine wound model to compare three dressings commonly used in burn centers for partial-thickness burns. Partial-thickness scalds were made on the flanks of pigs. Wounds were treated with silver sulfadiazine (SSD, flammazine), a hydrofiber dressing, or glycerol-preserved allogeneic (pig) skin. The healing process was monitored for 8 weeks. Macroscopic parameters were the itching behavior, the cosmetic appearance of the scars, and contraction. Microscopic parameters were the inflammatory response, myofibroblast influx, and the numbers of nerves. All wounds were closed on day 14 and wound infection did not occur. Treatment with SSD resulted in significantly more wound contraction compared to treatment with glycerol-preserved pig skin. Animals treated with SSD suffered more from itching (scratching) during the first 2 weeks after wounding. The number of nerves in healing wounds of these animals was significantly higher compared to wounds treated with hydrofiber dressing or allogeneic skin. In our standardized porcine partial-thickness wound model, treatment with SSD resulted in less favorable wound healing. Compared to treatment with glycerol-preserved allogeneic skin, SSD resulted in more contraction.

The risk of transmitting cutaneous malignancy through skin transplantation: a literature-based risk assessment.

According to the European Union Tissues and Cells Directives donation of tissue is contraindicated in the presence of or a previous history of malignant disease, with the exception of cutaneous basal cell carcinoma. Skin cancer is the most common cancer. Due to ultraviolet light exposure and increasing life expectancy an increasing prevalence of malignant or premalignant skin lesions is observed, which may result in a decline of the availability of skin for transplantation. A risk assessment based on published studies and expert opinion was performed in order to investigate the risk of transmitting malignant or premalignant skin lesions through tissue transplantation, and more particular through skin transplantation. The scarcity of data concerning cancer transmission in tissue transplantation was challenging. Circumstantial evidence, available for organ transplantation, was used to develop the following policy proposal for skin transplantation and cutaneous tumours. Malignant melanoma is an absolute contraindication for the donation of skin and also of other tissues, whereas, non-lesional skin and other tissues of a donor with non-melanoma skin cancer (basal cell and squamous cell carcinoma) or with a premalignant skin lesion can be considered for transplantation. The above mentioned protocol proposal might serve as a prototype for analogous protocols for non-cutaneous malignancies.

Glyaderm(®) dermal substitute: clinical application and long-term results in 55 patients.

INTRODUCTION: Glycerol preserved acellular dermis (Glyaderm(®)) consists of collagen and elastin fibers and is the first non-profit dermal substitute derived from glycerol-preserved, human allogeneic skin. It is indicated for bi-layered skin reconstruction of full thickness wounds. METHODS: A protocol for clinical application and optimal interval before autografting with split thickness skin graft (STSG) was developed in a pilot study. A phase III randomized, controlled, paired, intra-individual study compared full thickness defects engrafted with Glyaderm(®) and STSG versus STSG alone. Outcome measures included percentage of Glyaderm(®) take, STSG take, and scar quality assessment. RESULTS: Pilot study (27 patients): Mean take rates equaled 91.55% for Glyaderm(®) and 96.67% for STSG. The optimal autografting interval was 6 days (±1 day). Randomized trial (28 patients): Mean Glyaderm(®) take rate was 88.17%. STSG take rates were comparable for both research groups (p=0.588). One year after wound closure, Glyaderm(®)+STSG was significantly more elastic (p=0.003) than STSG alone. Blinded observers scored Glyaderm(®) treated wounds better in terms of scar quality. DISCUSSION: The efficacy of Glyaderm(®) as a suitable dermal substitute for full thickness wounds is attested. Currently a procedure for simultaneous application of Glyaderm(®) and STSG is adopted, allowing for further widespread use of Glyaderm(®).

Dectin-1 activation induces proliferation and migration of human keratinocytes enhancing wound re-epithelialization.

Beta-glucans in temporary wound dressings have immuno-stimulatory capacities and have been shown to enhance wound healing in burn patients. Curdlan is a 1,3-linked bacterial/fungal derived beta-glucan that induces inflammatory responses via the C-type lectin receptor dectin-1 on dendritic cells (DCs). Here we investigated the effect of beta-glucan curdlan and the role of dectin-1 expressed by keratinocytes (KCs) in wound healing. Curdlan enhanced migration, proliferation and wound closure of human KCs in a dectin-1 dependent manner, both in vitro and ex vivo. Our data suggest that curdlan induces human KC proliferation and migration and could therefore be used in creams to enhance wound healing.

Report of the clinical donor case workshop of the European Association of Tissue Banks annual meeting 2012.

The European Association of Tissue Banks (EATB) donor case workshop is a forum held within the program of the EATB annual congress. The workshop offers an opportunity to discuss and evaluate approaches taken to challenging situations regarding donor selection, it promotes consensus development in deciding tissue donor acceptability when donor health issues are not addressed in standards and regulations, and serves to strengthen the professional tissue banking networks across Europe and beyond. This report reflects some of the discussion at the workshop during the annual congress in Vienna in 2012. The cases presented dealt with problems encountered by tissue bank facilities concerning idiopathic thrombocytopenia and auto-immune disorders, hemodilution and blood sample identification, premalignant and malignant lesions, and Huntington's disease. The discussions during the workshop demonstrate that the implications on the safety of tissue transplantation of various tissue donor illnesses, physical findings and behaviours, and the preventive measures taken by tissue facilities, may not always be agreed by tissue facility medical directors and other professionals. Moreover, they reveal that operating procedures, regulations and standards cannot comprehensively cover all tissue donor findings, medical histories and circumstances surrounding the cause of death. For many of the issues raised, there is a need for scientific research to provide a better evidence base for future deliberations about the suitability and eligibility of tissue allograft donors.

Glycerol treatment as recovery procedure for cryopreserved human skin allografts positive for bacteria and fungi.

Human donor skin allografts are suitable and much used temporary biological (burn) wound dressings. They prepare the excised wound bed for final autografting and form an excellent substrate for revascularisation and for the formation of granulation tissue. Two preservation methods, glycerol preservation and cryopreservation, are commonly used by tissue banks for the long-term storage of skin grafts. The burn surgeons of the Queen Astrid Military Hospital preferentially use partly viable cryopreserved skin allografts. After mandatory 14-day bacterial and mycological culture, however, approximately 15% of the cryopreserved skin allografts cannot be released from quarantine because of positive culture. To maximize the use of our scarce and precious donor skin, we developed a glycerolisation-based recovery method for these culture positive cryopreserved allografts. The inactivation and preservation method, described in this paper, allowed for an efficient inactivation of the colonising bacteria and fungi, with the exception of spore-formers, and did not influence the structural and functional aspects of the skin allografts.

Administration of prednisolone phosphate-liposomes reduces wound contraction in a rat partial-thickness wound model.

Macrophages play an important role in the inflammatory phase of wound healing and their activity regulates fibroblasts and keratinocytes. Modulation of macrophage function may result in improvement of the wound healing process. Prednisolone phosphate (PLP) encapsulated into liposomes was administered to partial-thickness wounds in rats. A single dose of 75 microg/kg, applied directly after wounding, resulted in up to a 30% reduction of wound contraction at 28 days after wounding. This effect could not be achieved in the group that was administered free PLP or liposomes containing phosphate-buffered saline to the wound. The number of myofibroblasts was up to 50% lower in wounds treated with the liposomal PLP at 4 days after wounding. The number of macrophages present in the wounds was not statistically different between groups. Most probably, the production of cytokines and growth factors by macrophages is altered after phagocytosing the liposomes, resulting in reduced wound contraction.