The use of skin substitutes and burn care—a survey

Thymoquinone-Incorporated CollaGee Biomatrix: A Promising Approach for Full-Thickness Wound Healing

Wound infection is the leading cause of delayed wound healing. Despite ongoing research, the ideal treatment for full-thickness skin wounds is yet to be achieved. Skin tissue engineering provides an alternative treatment, with the potential for skin regeneration. Background/Objectives: Previously, we characterized a collagen-gelatin-elastin (CollaGee) acellular skin substitute and evaluated its cytocompatibility. The assessments revealed good physicochemical properties and cytocompatibility with human dermal fibroblasts (HDF). This study aimed to incorporate thymoquinone (TQ) as the antibacterial agent into CollaGee biomatrices and evaluate their cytocompatibility in vitro. Methods: Briefly, dose-response and antibacterial studies were conducted to confirm the antimicrobial activity and identify the suitable concentration for incorporation; 0.05 and 0.1 mg/mL concentrations were selected. Then, the cytocompatibility was evaluated quantitatively and qualitatively. Results: Cytocompatibility analysis revealed no toxicity towards HDFs, with 81.5 + 0.7% cell attachment and 99.27 + 1.6% cell viability. Specifically, the 0.05 mg/mL TQ concentration presented better viability, but the differences were not significant. Immunocytochemistry staining revealed the presence of collagen I, vinculin, and alpha smooth muscle actin within the three-dimensional biomatrices. Conclusions: These results suggest that TQ-incorporated CollaGee biomatrices are a promising candidate for enhancing the main key player, HDF, to efficiently regenerate the dermal layer in full-thickness skin wound healing. Further investigations are needed for future efficiency studies in animal models.

Barriers and prospects for skin grafting in burn treatment across African countries

INTRODUCTION

The current standard management of full-thickness or deep dermal burns is early tangential excision and skin grafting. A conservative approach to deep burns without the option of skin grafting results in delayed wound healing, possibly leading to wound infection and is associated with hypertrophic scarring and increased morbidity and mortality. The aim of this study was to improve the understanding of the management and availability to perform skin grafting for burns on the African continent. It also sought to identify challenges and perceived improvements.

METHODS

A web-based, structured, closed-formatted, multinational survey was designed to gather information on the current state and availability of skin grafting of burn wounds on the African continent. The questionnaire consisted of 27 questions, available in English and French. It was reviewed within the GAP-Burn collaboration network and sent to 271 health care professionals who had participated in a previous study and had initially been recruited by means of the snowball system.

RESULTS

The questionnaire was completed 84 times (response rate: 31.0%), of which 3 were excluded. Responses originated from 22 African countries. The majority 71 (87.7%) resulted from countries with a low Human Development Index (HDI), 7 (8.6%) from medium HDI countries. Split thickness skin grafting (STSG) is performed in 51 (63.0%) centers. The majority considers STSG to reduce length of stay (72.8%) and improve scarring (54.3%), yet some indicated that STSG is associated with increased risk of donor site infection (8.6%) and severe bleeding (7.4%). Factors preventing increased grafting included lack of equipment and training.

CONCLUSION

Skin grafting is not performed in a significant number of hospitals treating burns. The majority of the staff believe that more skin grafting would lead to a better outcome. Advocacy and improved infrastructure, human resources coupled with introduction to well-structured health coverage for all in African countries could help to better access and affordability in burn care.

Skin Bank Establishment in Treatment of Severe Burn Injuries: Overview and Experience with Skin Allografts at the Vienna Burn Center

Depending on their extent, burn injuries require different treatment strategies. In cases of severe large-area trauma, the availability of vital skin for autografting is limited. Donor skin allografts are a well-established but rarely standardized option for temporary wound coverage. Ten patients were eligible for inclusion in this retrospective study. Overall, 202 donor skin grafts obtained from the in-house skin bank were applied in the Department of Plastic and Reconstructive and Aesthetic Surgery, Medical University of Vienna. Between 2017 and 2022, we analysed the results in patient treatment, the selection of skin donors, tissue procurement, tissue processing and storage of allografts, as well as the condition and morphology of the allografts before application. The average Abbreviated Burn Severity Index (ABSI) was 8.5 (range, 5-12), and the mean affected total body surface area (TBSA) was 46.1% (range, 20-80%). In total, allograft application was performed 14 times. In two cases, a total of eight allografts were removed due to local infection, accounting for 3.96% of skin grafts. Six patients survived the acute phase of treatment. Scanning electron microscope images and histology showed no signs of scaffold decomposition and intact tissue layers of the allografts. The skin banking program and the application of skin allografts at the Vienna Burn Center can be considered successful. In severe burn injuries, skin allografts provide time by serving as sufficient wound coverage after early necrosectomy. Having an in-house skin banking program at a dedicated burn centre is particularly advantageous since issues of availability and distribution can be minimized. Skin allografts provide a reliable treatment option in patients with extensive burn injuries.

Development of Radiosterilized Porcine Skin Electrosprayed with Silver Nanoparticles Prevents Infections in Deep Burns

Extensive burns represent a significant challenge in biomedicine due to the multiple systemic and localized complications resulting from the major skin barrier loss. The functionalization of xenografts with nanostructured antibacterial agents proposes a fast and accessible application to restore barrier function and prevent localized bacterial contamination. Based on this, the objective of this work was to functionalize a xenograft by electrospray deposition with silver nanoparticles (AgNPs) and to evaluate its antibiofilm and cytotoxic effects on human fibroblasts. Initially, AgNPs were synthesized by a green microwave route with sizes of 2.1, 6.8, and 12.2 nm and concentrations of 0.055, 0.167, and 0.500 M, respectively. The AgNPs showed a size relationship directly proportional to the concentration of AgNO3, with a spherical and homogeneous distribution determined by high-resolution transmission electron microscopy. The surface functionalization of radiosterilized porcine skin (RPS) via electrospray deposition with the three AgNP concentrations (0.055, 0.167, and 0.500 M) in the epidermis and the dermis showed a uniform distribution on both surfaces by energy-dispersive X-ray spectroscopy. The antibiofilm assays of clinical multidrug-resistant Pseudomonas aeruginosa showed significant effects at the concentrations of 0.167 and 0.500 M, with a log reduction of 1.3 and 2.6, respectively. Additionally, viability experiments with human dermal fibroblasts (HDF) exposed to AgNPs released from functionalized porcine skin showed favorable tolerance, with retention of viability more significant than 90% for concentrations of 0.05 and 0.167 M after 24 h exposure. Antibacterial activity combined with excellent biocompatibility makes this biomaterial a candidate for antibacterial protection by inhibiting bacterial biofilms in deep burns during early stages of development.

Adipose stromal vascular fraction: a promising treatment for severe burn injury

Thermal skin burn injury affects both adults and children globally. Severe burn injury affects a patient's life psychologically, cosmetically, and socially. The pathophysiology of burn injury is well known. Due to the complexity of burn pathophysiology, the development of specific treatment aiding in tissue regeneration is required. Treatment of burn injury depends on burn severity, size of the burn and availability of donor site. Burn healing requires biochemical and cellular events to ensure better cell response to biochemical signals of the healing process. This led to the consideration of using cell therapy for severe burn injury. Adult mesenchymal stem cells have become a therapeutic option because of their ability for self-renewal and differentiation. Adipose stromal vascular fraction (SVF), isolated from adipose tissues, is a heterogeneous cell population that contains adipose-derived stromal/stem cells (ADSC), stromal, endothelial, hematopoietic and pericytic lineages. SVF isolation has advantages over other types of cells; such as heterogeneity of cells, lower invasive extraction procedure, high yield of cells, and fast and easy isolation. Therefore, SVF has many characteristics that enable them to be a therapeutic option for burn treatment. Studies have been conducted mostly in animal models to investigate their therapeutic potential for burn injury. They can be used alone or in combination with other treatment options. Treatment with both ADSCs and/or SVF enhances burn healing through increasing re-epithelization, angiogenesis and decreasing inflammation and scar formation. Research needs to be conducted for a better understanding of the SVF mechanism in burn healing and to optimize current techniques for enhanced treatment outcomes.

Human skin processing affects clinical outcome in allograft recipients

Skin allografts represent a milestone in burn patient treatment. However, skin procurement is still burdened by high rates of contamination, and validation procedures have not yet been standardized. In addition, it is not clear if tissue viability affects allograft skin outcomes. In 2120 skin samples from 610 donors, a retrospective analysis was performed to identify donor and procurement variables associated with bacterial contamination and tissue viability. Post-processing contamination was associated significantly with the donor type, cause of death, length of hospitalization, procurement site, surgeon, interval between procurement and banking, and decontamination method. Tissue viability appeared to be negatively associated with freezing. In two series of skin allograft recipients (155 and 195 patients), we evaluated the role of skin characteristics and procurement variables on clinical outcomes. We found that the length of hospitalization was associated significantly with donor age. Procalcitonin and PCR values in allograft recipients were correlated with the decontamination method. No significant associations were observed between tissue viability and clinical outcomes (length of hospitalization, cause of donor death, or inflammatory parameters) after allograft transplantation. In these large case series, we identified donor and procurement variables that may affect allograft skin recipients. The decontamination method appeared to be a critical step for skin allograft requiring better standardization.

Skin regeneration, repair, and reconstruction: present and future

Background

Large skin defects caused by trauma (e.g., burns) or due to other reasons (e.g., tumor-related skin resections) require sufficient skin replacement. The constant improvement of innovative methods of skin replacement and skin expansion mean that even burn victims with more than 80% body surface burned have a realistic chance of survival. Due to these new developments, not only has survival rate increased, but also quality of life has increased tremendously over the past decades.

Methods

The aim of this review is to present an overview of current standards and future trends concerning the treatment of skin defects. The main focus is placed on the most important technologies and future trends.

Results

Autologous skin grafting was developed more than 3500 years ago. Several approaches and techniques have been discovered and established in burn care and plastic surgery since then. Great achievements were made during the 19th and 20th centuries. Many of these old and new techniques are still part of modern burn and plastic surgery. Today, autologous skin grafting is still considered to be the gold standard for many wounds, but new technologies have been developed, ranging from biological to synthetic skin replacement materials.

Conclusion

Today, old and new technologies are available which allow us new treatment concepts. All this has led to the reconstructive clockwork for reconstructive surgery of the 21st century.

A Beginner's Introduction to Skin Stem Cells and Wound Healing

The primary function of the skin is that of a physical barrier against the environment and diverse pathogens; therefore, its integrity is essential for survival. Skin regeneration depends on multiple stem cell compartments within the epidermis, which, despite their different transcriptional and proliferative capacity, as well as different anatomical location, fall under the general term of skin stem cells (SSCs). Skin wounds can normally heal without problem; however, some diseases or extensive damage may delay or prevent healing. Non-healing wounds represent a serious and life-threatening scenario that may require advanced therapeutic strategies. In this regard, increased focus has been directed at SSCs and their role in wound healing, although emerging therapeutical approaches are considering the use of other stem cells instead, such as mesenchymal stem cells (MSCs). Given its extensive and broad nature, this review supplies newcomers with an introduction to SSCs, wound healing, and therapeutic strategies for skin regeneration, thus familiarizing the reader with the subject in preparation for future in depth reading.

Advances in Skin Tissue Bioengineering and the Challenges of Clinical Translation

Skin tissue bioengineering is an emerging field that brings together interdisciplinary teams to promote successful translation to clinical care. Extensive deep tissue injuries, such as large burns and other major skin loss conditions, are medical indications where bioengineered skin substitutes (that restore both dermal and epidermal tissues) are being studied as alternatives. These may not only reduce mortality but also lessen morbidity to improve quality of life and functional outcome compared with the current standards of care. A common objective of dermal-epidermal therapies is to reduce the time required to accomplish stable closure of wounds with minimal scar in patients with insufficient donor sites for autologous split-thickness skin grafts. However, no commercially-available product has yet fully satisfied this objective. Tissue engineered skin may include cells, biopolymer scaffolds and drugs, and requires regulatory review to demonstrate safety and efficacy. They must be scalable for manufacturing and distribution. The advancement of technology and the introduction of bioreactors and bio-printing for skin tissue engineering may facilitate clinical products' availability. This mini-review elucidates the reasons for the few available commercial skin substitutes. In addition, it provides insights into the challenges faced by surgeons and scientists to develop new therapies and deliver the results of translational research to improve patient care.

Glucose Metabolism in Burns-What Happens?

Severe burns represent an important challenge for patients and medical teams. They lead to profound metabolic alterations, trigger a systemic inflammatory response, crush the immune defense, impair the function of the heart, lungs, kidneys, liver, etc. The metabolism is shifted towards a hypermetabolic state, and this situation might persist for years after the burn, having deleterious consequences for the patient's health. Severely burned patients lack energy substrates and react in order to produce and maintain augmented levels of glucose, which is the fuel "ready to use" by cells. In this paper, we discuss biological substances that induce a hyperglycemic response, concur to insulin resistance, and determine cell disturbance after a severe burn. We also focus on the most effective agents that provide pharmacological modulations of the changes in glucose metabolism.

Porcine Xenograft and Epidermal Fully Synthetic Skin Substitutes in the Treatment of Partial-Thickness Burns: A Literature Review

Background and Objectives: Porcine xenografts have been used successfully in partial thickness burn treatment for many years. Their disappearance from the market led to the search for effective and efficient alternatives. In this article, we examine the synthetic epidermal skin substitute Suprathel^® as a substitute in the treatment of partial thickness burns. Materials and Methods: A systematic review following the PRISMA guidelines has been performed. Sixteen Suprathel^® and 12 porcine xenograft studies could be included. Advantages and disadvantages between the treatments and the studies’ primary endpoints have been investigated qualitatively and quantitatively. Results: Although Suprathel had a nearly six times larger TBSA in their studies (p < 0.001), it showed a significantly lower necessity for skin grafts (p < 0.001), and we found a significantly lower infection rate (p < 0.001) than in Porcine Xenografts. Nonetheless, no significant differences in the healing time (p = 0.67) and the number of dressing changes until complete wound healing (p = 0.139) could be found. Both products reduced pain to various degrees with the impression of a better performance of Suprathel^® on a qualitative level. Porcine xenograft was not recommended for donor sites or coverage of sheet-transplanted keratinocytes, while Suprathel^® was used successfully in both indications. Conclusion: The investigated parameters indicate that Suprathel^® to be an effective replacement for porcine xenografts with even lower subsequent treatment rates. Suprathel^® appears to be usable in an extended range of indications compared to porcine xenograft. Data heterogeneity limited conclusions from the results.

Intermediate Skin Substitutes Are Unnecessary in Small (<10% TBSA) Burns

The use of intermediate skin substitutes between debridement and final autografting is routine for many practitioners. Materials such as xenografts and allografts have been promoted to help with wound coverage before autografting. However, there is limited data for their use in relatively small burn wounds (<10% TBSA). In this study, we analyzed the outcomes of 100 consecutive patients who underwent autografting for burns <10% TBSA at our American Burn Association-verified burn unit in the absence of intermediate skin substitute use. We retrospectively analyzed 100 patients who underwent split thickness skin graft autografting for burns <10% TBSA between November 2017 and June 2019. No patients were treated with intermediate skin substitutes. Analysis included basic demographics, comorbidities, TBSA burned, mechanism of burn, time to grafting, if grafting was performed in a single procedure or staged, graft loss (>50% graft failure), and time to complete healing (no further wound care required). Twelve patients (12%) had unpredictable graft beds, and their procedure was staged. These patients underwent surgical debridement and were dressed in antimicrobial dressing for an average of 5 days before autografting. No patients had intermediate skin substitutes between procedures. Eighty-eight patients (88%) were debrided and grafted in a single stage. In the staged group, there was a 0% rate of graft failure compared with 9.1% rate of graft failure in the primarily grafted group (P = .004). There was a similar length of stay and time to complete healing in the staged group and primarily grafted group (P = .496 and P = .571). There was a significantly shorter time from injury to first procedure between the staged group and the primarily grafted group (8.7 days and 13.5 days, P = .014). In the eight instances of graft failure, infection or inadequate debridement was the cause. Seven of these eight cases required further surgical intervention. Intermediate skin substitutes are an unnecessary step in grafting small burns. These add only complexity and cost to patient care. Many patients can be debrided and grafted in a single stage. Debridement alone with delayed grafting is a highly effective surgical method when the wound bed is not suitable for immediate grafting. The use of intermediate skin substitutes in small burns requires further investigation as this study finds low benefit for this product.

Topical treatment for facial burns

BACKGROUND

Burn injuries are an important health problem. They occur frequently in the head and neck region. The face is the area central to a person's identity that provides our most expressive means of communication. Topical interventions are currently the cornerstone of treatment of burns to the face.

OBJECTIVES

To assess the effects of topical interventions on wound healing in people with facial burns of any depth.

SEARCH METHODS

In December 2019 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that evaluated the effects of topical treatment for facial burns were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, data extraction, risk of bias assessment and GRADE assessment of the certainty of the evidence.

MAIN RESULTS

In this first update, we included 12 RCTs, comprising 507 participants. Most trials included adults admitted to specialised burn centres after recent burn injuries. Topical agents included antimicrobial agents (silver sulphadiazine (SSD), Aquacel-Ag, cerium-sulphadiazine, gentamicin cream, mafenide acetate cream, bacitracin), non-antimicrobial agents (Moist Exposed Burn Ointment (MEBO), saline-soaked dressings, skin substitutes (including bioengineered skin substitute (TransCyte), allograft, and xenograft (porcine Xenoderm), and miscellaneous treatments (growth hormone therapy, recombinant human granulocyte-macrophage colony-stimulating factor hydrogel (rhGMCS)), enzymatic debridement, and cream with Helix Aspersa extract). Almost all the evidence included in this review was assessed as low or very low-certainty, often because of high risk of bias due to unclear randomisation procedures (i.e. sequence generation and allocation concealment); lack of blinding of participants, providers and sometimes outcome assessors; and imprecision resulting from few participants, low event rates or both, often in single studies. Topical antimicrobial agents versus topical non-antimicrobial agents There is moderate-certainty evidence that there is probably little or no difference between antimicrobial agents and non-antimicrobial agents (SSD and MEBO) in time to complete wound healing (hazard ratio (HR) 0.84 (95% confidence interval (CI) 0.78 to 1.85, 1 study, 39 participants). Topical antimicrobial agents may make little or no difference to the proportion of wounds completely healed compared with topical non-antimicrobial agents (comparison SSD and MEBO, risk ratio (RR) 0.94, 95% CI 0.68 to 1.29; 1 study, 39 participants; low-certainty evidence). We are uncertain whether there is a difference in wound infection (comparison topical antimicrobial agent (Aquacel-Ag) and MEBO; RR 0.38, 95% CI 0.12 to 1.21; 1 study, 40 participants; very low-certainty evidence). No trials reported change in wound surface area over time or partial wound healing. There is low-certainty evidence for the secondary outcomes scar quality and patient satisfaction. Two studies assessed pain but it was incompletely reported. Topical antimicrobial agents versus other topical antimicrobial agents It is uncertain whether topical antimicrobial agents make any difference in effects as the evidence is low to very low-certainty. For primary outcomes, there is low-certainty evidence for time to partial (i.e. greater than 90%) wound healing (comparison SSD versus cerium SSD: mean difference (MD) -7.10 days, 95% CI -16.43 to 2.23; 1 study, 142 participants). There is very low-certainty evidence regarding whether topical antimicrobial agents make a difference to wound infection (RR 0.73, 95% CI 0.46 to 1.17; 1 study, 15 participants). There is low to very low-certainty evidence for the proportion of facial burns requiring surgery, pain, scar quality, adverse effects and length of hospital stay. Skin substitutes versus topical antimicrobial agents There is low-certainty evidence that a skin substitute may slightly reduce time to partial (i.e. greater than 90%) wound healing, compared with a non-specified antibacterial agent (MD -6.00 days, 95% CI -8.69 to -3.31; 1 study, 34 participants). We are uncertain whether skin substitutes in general make any other difference in effects as the evidence is very low certainty. Outcomes included wound infection, pain, scar quality, adverse effects of treatment and length of hospital stay. Single studies showed contrasting low-certainty evidence. A bioengineered skin substitute may slightly reduce procedural pain (MD -4.00, 95% CI -5.05 to -2.95; 34 participants) and background pain (MD -2.00, 95% CI -3.05 to -0.95; 34 participants) compared with an unspecified antimicrobial agent. In contrast, a biological dressing (porcine Xenoderm) might slightly increase pain in superficial burns (MD 1.20, 95% CI 0.65 to 1.75; 15 participants (30 wounds)) as well as deep partial thickness burns (MD 3.00, 95% CI 2.34 to 3.66; 10 participants (20 wounds)), compared with antimicrobial agents (Physiotulle Ag (Coloplast)). Miscellaneous treatments versus miscellaneous treatments Single studies show low to very low-certainty effects of interventions. Low-certainty evidence shows that MEBO may slightly reduce time to complete wound healing compared with saline soaked dressing (MD -1.7 days, 95% CI -3.32 to -0.08; 40 participants). In addition, a cream containing Helix Aspersa may slightly increase the proportion of wounds completely healed at 14 days compared with MEBO (RR 4.77, 95% CI 1.87 to 12.15; 43 participants). We are uncertain whether any miscellaneous treatment in the included studies makes a difference in effects for the outcomes wound infection, scar quality, pain and patient satisfaction as the evidence is low to very low-certainty.

AUTHORS' CONCLUSIONS

There is mainly low to very low-certainty evidence on the effects of any topical intervention on wound healing in people with facial burns. The number of RCTs in burn care is growing, but the body of evidence is still hampered due to an insufficient number of studies that follow appropriate evidence-based standards of conducting and reporting RCTs.

Bovine Decellularized Amniotic Membrane: Extracellular Matrix as Scaffold for Mammalian Skin

Decellularized membranes (DM) were obtained from bovine amniotic membranes (BAM) using four different decellularization protocols, based on physical, chemical, and mechanical treatment. The new material was used as a biological scaffold for in vitro skin cell culture. The DM were characterized using hematoxylin-eosin assay, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR-ATR), and differential scanning calorimetry (DSC). The in vitro cytotoxicity of DM was evaluated using MTT. The efficacy of decellularization process was assessed through DNA quantification and electrophoresis. All the used protocols showed a high effectiveness in terms of elimination of native cells, confirmed by DNA extraction and quantification, electrophoresis, and SEM, although protocol IV removes the cellular contents and preserve the native extracellular matrix (ECM) architecture which it can be considered as the most effective in terms of decellularization. FTIR-ATR and DSC on the other hand, revealed the effects of decellularization on the biochemical composition of the matrices. There was no cytotoxicity and the biological matrices obtained were a source of collagen for recellularization. The matrices of protocols I, II, and III were degraded at day 21 of cell culture, forming a gel. The biocompatibility in vitro was demonstrated; hence these matrices may be deemed as potential scaffold for epithelial tissue regeneration.

Skin substitutes for acute and chronic wound healing: an updated review

Background: Skin substitutes are designed to accelerate wound healing by providing replacement of extracellular matrix and can be used to promote healing of both acute and chronic wounds.Aim: To describe advantages, disadvantages, and indications for different skin substitutes with the intention of providing a systematic framework that clinicians can easily utilize in clinical practice.Materials and method: We conducted a PubMed, Cochrane Library, and company website search for publications using various search terms associated with skin substitutes.Results: Skin substitutes can be categorized as epidermal, dermal, and composite, depending on the skin component they contain, and further split into different categories depending on their composition and source of material, including xenograft, acellular allograft, cellular allograft, autograft, and synthetic skin substitutes. Because there is no ideal option for skin substitutes that meet all the criteria for optimal wound healing, there is ongoing research evaluating and developing different skin substitute options.Conclusion: Our model of skin substitutes was organized based on the different layers of cutaneous involvement and the origin of the product material. We believe that this framework provides a practical guide for selection of the most appropriate skin substitute based on clinical indication.

Feasibility of Pure Silk for the Treatment of Large Superficial Burn Wounds Covering Over 10% of the Total Body Surface

Large, superficial burn wounds require many painful dressing changes and, thus, dressings that can stay on the wound and peel off during re-epithelization such as Biobrane® and Suprathel® are preferred, but they are costly. Natural silk has shown good outcomes with respect to wound healing, scarring, and patient satisfaction. This study aimed to evaluate the efficacy of natural silk compared with that of initially used dressings for the treatment of superficial burn wounds greater than 10% of the TBSA. Patients with superficial burns covering &gt;10% of the TBSA were treated with pure silk for the first time (treatment group). Complications during wound healing with respect to the need for further surgery and scarring were compared with those of patients with similar burns of more than 10% TBSA and treated with nylon mesh and collagen instead of silk (treatment group). The treatment and control group comprised 25 and 13 patients, respectively. In total, 88% of patients in the treatment group did not require further treatment, while two patients with chemical burns needed further surgeries. Moreover, patients reported high satisfaction with respect to scarring and aesthetic outcome. Meanwhile, 85% of patients in the control group healed without further surgery and showed higher median hypopigmentation and hyperpigmentation after 12 months. Silk is an effective wound dressing for the treatment of large superficial burn wounds. It avoids painful dressing changes and yields satisfactory aesthetic outcomes. However, especially in large burns, careful initial wound depth assessment is crucial to prevent infection and reoperations.

Epidermal stem cells in wound healing and their clinical applications

The skin has important barrier, sensory, and immune functions, contributing to the health and integrity of the organism. Extensive skin injuries that threaten the entire organism require immediate and effective treatment. Wound healing is a natural response, but in severe conditions, such as burns and diabetes, this process is insufficient to achieve effective treatment. Epidermal stem cells (EPSCs) are a multipotent cell type and are committed to the formation and differentiation of the functional epidermis. As the contributions of EPSCs in wound healing and tissue regeneration have been increasingly attracting the attention of researchers, a rising number of therapies based on EPSCs are currently under development. In this paper, we review the characteristics of EPSCs and the mechanisms underlying their functions during wound healing. Applications of EPSCs are also discussed to determine the potential and feasibility of using EPSCs clinically in wound healing.

Is allograft skin, the gold-standard for burn skin substitute? A systematic literature review and meta-analysis

BACKGROUND

Allograft skin (AS) transplantation has been considered to be the gold standard for replacing tissue damage, following burns. However, increasingly new biosynthetic skin substitutes are being developed as alternatives. The objective of this systematic review is to compare AS with other skin substitutes, which have been used in the treatment of burns.

METHODS

Randomized clinical trial (RCT) and nonrandomized clinical trial (NRCT) studies comparing AS to any other skin substitute in the treatment of burns were extracted from PubMed/Medline, Scopus, EMBASE, and Web of Science. For the risk of bias analysis, the Cochrane bias risk handbook was used for RCT studies and ROBINS-1 was used for NRCT studies. Outcomes such as healing, self-grafting, scar appearance, and mortality were evaluated.

RESULTS

Twelve RCT and six NRCT were selected, with most of the methodologies presenting a high risk of bias. Based on the outcomes of the studies, it was not possible to detect any advantages for using AS, as opposed to other skin substitutes. In the meta-analysis, only two outcomes could be evaluated: healing and graft take percentage; however, no significant differences were observed between the groups.

CONCLUSION

Because of the poor quality of the primary studies, it was not possible to identify differences in the results that compared the use of AS with other substitutes in the treatment of patients with burns. These results support the fact that surgeons primarily base the choice of skin substitute on clinical experience and cost, at least when treating burns.

The Role of Biological Skin Substitutes in Stevens-Johnson Syndrome: Systematic Review

Stevens-Johnson syndrome (SJS) is a disease that causes skin exfoliative lesions, characterized by fever, necrosis, and epidermal detachment. Biological skin substitutes may be considered interesting options for the treatment of this disease. This study aims at identifying in the literature the evidence on the current role of these biomaterials in the treatment of SJS and its related diseases. A systematic review with a search period between 2003 and 2017 was carried out, consulting the Lilacs, BVS, and PubMed databases. The quality of the included studies was evaluated by the Oxford Center for Evidence-Based Medicine Classification, for evaluating levels of evidence from the scientific publications. Ninety-five publications were found, and after applying inclusion and exclusion criteria, they resulted in 9 articles. In total, 20 patients with 73.87% average of body surface affected received SJS skin treatment with some biological substitutes, among them are cutaneous allograft, amnion, and xenograft. Mortality rate was 10%, and in these situations, literature indicates mortality rates ranging from 25% to 70%. Effectiveness of the use of biological dressings may be a possible explanation for this finding. Findings indicate the use of these biomaterials may favor reepithelialization, reduce water loss, decrease the chance of infection, and, consequently, improve the survival of patients with SJS and toxic epidermal necrolysis. Biological skin substitutes have characteristics that make them very promising in the topical treatment of these wounds, but their use remains very restricted in the treatment of SJS.

3D Protein-Based Bilayer Artificial Skin for the Guided Scarless Healing of Third-Degree Burn Wounds in Vivo

Severe burn injuries can lead to delays in healing and devastating scar formation. Attempts have been made to develop a suitable skin substitute for the scarless healing of such skin wounds. Currently, there is no effective strategy for completely scarless healing after the thermal injuries. In our recent work, we fabricated and evaluated a 3D protein-based artificial skin made from decellularized human amniotic membrane (AM) and electrospun nanofibrous silk fibroin (ESF) in vitro. We also characterized both biophysical and cell culture investigation to establish in vitro performance of the developed bilayer scaffolds. In this report, we evaluate the appropriate utility of this fabricated bilayered artificial skin in vivo with particular emphasis on healing and scar formation due to the biochemical and biomechanical complexity of the skin. For this work, AM and AM/ESF membranes alone or seeded with adipose-tissue-derived mesenchymal stem cells (AT-MSCs) are implanted on full-thickness burn wounds in mice. The healing efficacy and scar formation are evaluated at 7, 14, and 28 days post-implantation in vivo. Our data reveal that ESF accelerates the wound-healing process through the early recruitment of inflammatory cells such as macrophages into the defective site as well as the up-regulation of angiogenic factors from the AT-MSCs and the facilitation of the remodeling phase. In vivo application of the prepared AM/ESF membrane seeded with the AT-MSCs reduces significantly the post-burn scars. The in vivo data suggest that the potential applications of the AM/ESF bilayered artificial skin may be considered a clinical translational product with stem cells to guide the scarless healing of severe burn injuries.

Advancements in Regenerative Strategies Through the Continuum of Burn Care

Burns are caused by several mechanisms including flame, scald, chemical, electrical, and ionizing and non-ionizing radiation. Approximately half a million burn cases are registered annually, of which 40 thousand patients are hospitalized and receive definitive treatment. Burn care is very resource intensive as the treatment regimens and length of hospitalization are substantial. Burn wounds are classified based on depth as superficial (first degree), partial-thickness (second degree), or full-thickness (third degree), which determines the treatment necessary for successful healing. The goal of burn wound care is to fully restore the barrier function of the tissue as quickly as possible while minimizing infection, scarring, and contracture. The aim of this review is to highlight how tissue engineering and regenerative medicine strategies are being used to address the unique challenges of burn wound healing and define the current gaps in care for both partial- and full-thickness burn injuries. This review will present the current standard of care (SOC) and provide information on various treatment options that have been tested pre-clinically or are currently in clinical trials. Due to the complexity of burn wound healing compared to other skin injuries, burn specific treatment regimens must be developed. Recently, tissue engineering and regenerative medicine strategies have been developed to improve skin regeneration that can restore normal skin physiology and limit adverse outcomes, such as infection, delayed re-epithelialization, and scarring. Our emphasis will be centered on how current clinical and pre-clinical research of pharmacological agents, biomaterials, and cellular-based therapies can be applied throughout the continuum of burn care by targeting the stages of wound healing: hemostasis, inflammation, cell proliferation, and matrix remodeling.

Skin xenotransplantation: Historical review and clinical potential

Half a million patients in the USA alone require treatment for burns annually. Following an extensive burn, it may not be possible to provide sufficient autografts in a single setting. Pig skin xenografts may provide temporary coverage. However, preformed xenoreactive antibodies in the human recipient activate complement, and thus result in rapid rejection of the graft. Because burn patients usually have some degree of immune dysfunction and are therefore at increased risk of infection, immunosuppressive therapy is undesirable. Genetic engineering of the pig has increased the survival of pig heart, kidney, islet, and corneal grafts in immunosuppressed non-human primates from minutes to months or occasionally years. We summarize the current status of research into skin xenotransplantation for burns, with special emphasis on developments in genetic engineering of pigs to protect the graft from immunological injury. A genetically-engineered pig skin graft now survives as long as an allograft and, importantly, rejection of a skin xenograft is not detrimental to a subsequent allograft. Nevertheless, currently, systemic immunosuppressive therapy would still be required to inhibit a cellular response, and so we discuss what further genetic manipulations could be carried out to inhibit the cellular response.

Stem cells, niches and scaffolds: Applications to burns and wound care

The importance of skin to survival, and the devastating physical and psychological consequences of scarring following reparative healing of extensive or difficult to heal human wounds, cannot be disputed. We discuss the significant challenges faced by patients and healthcare providers alike in treating these wounds. New state of the art technologies have provided remarkable insights into the role of skin stem and progenitor cells and their niches in maintaining skin homeostasis and in reparative wound healing. Based on this knowledge, we examine different approaches to repair extensive burn injury and chronic wounds, including full and split thickness skin grafts, temporising matrices and scaffolds, and composite cultured skin products. Notable developments include next generation skin substitutes to replace split thickness skin autografts and next generation gene editing coupled with cell therapies to treat genodermatoses. Further refinements are predicted with the advent of bioprinting technologies, and newly defined biomaterials and autologous cell sources that can be engineered to more accurately replicate human skin architecture, function and cosmesis. These advances will undoubtedly improve quality of life for patients with extensive burns and difficult to heal wounds.

Tissue Source and Cell Expansion Condition Influence Phenotypic Changes of Adipose-Derived Stem Cells

Stem cells derived from the subcutaneous adipose tissue of debrided burned skin represent an appealing source of adipose-derived stem cells (ASCs) for regenerative medicine. Traditional tissue culture uses fetal bovine serum (FBS), which complicates utilization of ASCs in human medicine. Human platelet lysate (hPL) is one potential xeno-free, alternative supplement for use in ASC culture. In this study, adipogenic and osteogenic differentiation in media supplemented with 10% FBS or 10% hPL was compared in human ASCs derived from abdominoplasty (HAP) or from adipose associated with debrided burned skin (BH). Most (95–99%) cells cultured in FBS were stained positive for CD73, CD90, CD105, and CD142. FBS supplementation was associated with increased triglyceride content and expression of adipogenic genes. Culture in hPL significantly decreased surface staining of CD105 by 31% and 48% and CD142 by 27% and 35% in HAP and BH, respectively (p < 0.05). Culture of BH-ASCs in hPL also increased expression of markers of osteogenesis and increased ALP activity. These data indicate that application of ASCs for wound healing may be influenced by ASC source as well as culture conditions used to expand them. As such, these factors must be taken into consideration before ASCs are used for regenerative purposes.

Cultured epidermal stem cells in regenerative medicine

Transplantation of cultured epidermal cell sheets (CES) has long been used to treat patients with burns, chronic wounds, and stable vitiligo. In patients with large area burns this can be a life-saving procedure. The ultimate goal, however, is to restore all normal functions of the skin and prevent scar formation. Increased focus on the incorporation of epidermal stem cells (EpiSCs) within CES transplants may ultimately prove to be key to achieving this. Transplanted EpiSCs contribute to restoring the complete epidermis and provide long-term renewal.Maintenance of the regenerative potential of EpiSCs is anchorage-dependent. The extracellular matrix (ECM) provides physical cues that are interpreted by EpiSCs and reciprocal signaling between cells and ECM are integrated to determine cell fate. Thus, the carrier scaffold chosen for culture and transplant influences maintenance of EpiSC phenotype and may enhance or detract from regenerative healing following transfer.Long-term effectiveness and safety of genetically modified EpiSCs to correct the severe skin blistering disease epidermolysis bullosa has been shown clinically. Furthermore, skin is gaining interest as an easily accessible source of adult epithelial stem cells potentially useful for restoration of other types of epithelia. This review highlights the role of EpiSCs in the current treatment of skin injury and disease, as well as their potential in novel regenerative medicine applications involving other epithelia.