Outcome of Burns Treated With Autologous Cultured Proliferating Epidermal Cells: A Prospective Randomized Multicenter Intrapatient Comparative Trial

Knowledge, attitude, and practice of orthopedic, vascular surgery, and anesthesiology doctors regarding postoperative deep vein thrombosis prevention in surgical patients

Orthopedic and vascular surgeries carry a high risk of postoperative deep vein thrombosis (DVT). This cross-sectional study assessed the knowledge, attitude, and practice (KAP) of orthopedists, vascular surgeons, and anesthesiologists regarding postoperative DVT prevention in surgical patients. The study was performed at two hospitals in China from November 22 to December 13, 2023. Demographic information and KAP data were collected using a self-administered questionnaire. Among 294 doctors, 187 (63.61%) were male, and 248 (84.35%) had prior experience in orthopedic surgeries. Mean scores for knowledge, attitude, and practice were 9.94 ± 1.91, 37.12 ± 2.94, and 23.02 ± 3.64, respectively. Knowledge was correlated to attitude (r = 0.182, P = 0.002), knowledge to practice (r = 0.234, P < 0.001), and attitude to practice (r = 0.281, P < 0.001). Attitude score (OR = 1.249, 95% CI: [1.127-1.385], P < 0.001) and anesthesiology work (OR = 0.309, 95% CI: [0.158-0.603], P = 0.001) were independently associated with proactive practice. Structural equation modeling confirmed direct impacts of knowledge on attitude (β = 0.894, P < 0.001) and practice (β = 1.786, P < 0.001) and of attitude on practice (β = 0.338, P = 0.017). In conclusion, orthopedists, vascular surgeons, and anesthesiologists showed good knowledge, attitude, and practice toward DVT prevention in surgical patients in two hospitals in China.

Towards propagation of epidermal cells for wound repair: glass, as cell culture substrate, enhances proliferation and migration of human keratinocytes

Introduction

Human keratinocytes require relatively long propagation time which impedes their availability as autologous cell transplantation within a clinically reasonable timeframe. There is an unmet need for efficient xeno-free cell expansion approaches to propagate human keratinocytes as regenerative therapy.

Methods

Primary human keratinocytes and HaCaT cells were cultured on glass, plastic, and animal-derived collagen I matrix for 10 days. Proliferation, migration, DNA methylation, as well as gene and protein expression were assessed to characterize the effect of the tested culture substrates on keratinocytes at the molecular and functional levels.

Results

Keratinocytes cultured on glass exhibited faster proliferation, global DNA demethylation and upregulation of epidermal differentiation markers. Scratch wound assay revealed that keratinocytes cultured on glass demonstrated enhanced cell migration compared to those on plastic or collagen I. Multiplex immunoassays identified temporal and substrate-dependent variations in a panel of keratinocyte-specific secreted factors, encompassing immunomodulatory cytokines, growth factors, and angiogenic factors.

Discussion

Glass, as a culture substrate, promotes epidermal differentiation and enhances keratinocyte migration. The latter is a critical factor in re-epithelialization and wound healing. Functional properties suggest that glass may optimize the inflammatory response and promote efficient wound repair, making it a promising candidate for the short-term expansion of keratinocytes for transplantation purposes. Further in-vivo validation is required to definitively establish the efficacy of keratinocytes cultured on glass for clinical applications.

Advancements in bioengineered and autologous skin grafting techniques for skin reconstruction: a comprehensive review

The reconstruction of complex skin defects challenges clinical practice, with autologous skin grafts (ASGs) as the traditional choice due to their high graft take rate and patient compatibility. However, ASGs have limitations such as donor site morbidity, limited tissue availability, and the necessity for multiple surgeries in severe cases. Bioengineered skin grafts (BSGs) aim to address these drawbacks through advanced tissue engineering and biomaterial science. This study conducts a systematic review to describe the benefits and shortcomings of BSGs and ASGs across wound healing efficacy, tissue integration, immunogenicity, and functional outcomes focusing on wound re-epithelialization, graft survival, and overall aesthetic outcomes. Preliminary findings suggest ASGs show superior early results, while BSGs demonstrate comparable long-term outcomes with reduced donor site morbidity. This comparative analysis enhances understanding of bioengineered alternatives in skin reconstruction, potentially redefining best practices based on efficacy, safety, and patient-centric outcomes, highlighting the need for further innovation in bioengineered solutions.

Comparison of dermal and eschar fibroblasts in full skin equivalents

Full-thickness burn wounds pose significant problems, demanding specialised therapies to avoid complications and promote recovery. Eschar tissue, which forms in response to severe burns, contains viable fibroblasts, which migrate from the surrounding tissue in response to burn injury and exhibit a myofibroblast phenotype. The goal of this study was to characterise eschar-derived fibroblasts and examine their use for engineered in vitro full skin equivalents in comparison to normal dermal fibroblasts, which were harvested from non-injured skin. Microarray analysis indicated that eschar fibroblasts differ from dermal fibroblasts in various biological processes including inflammation, extracellular matrix formation, cell migration and differentiation. Skin equivalents with eschar fibroblasts showed similarities to those generated using normal dermal fibroblasts in terms of epidermis and dermis formation. However, in contrast to dermal fibroblast-based full skin equivalents, eschar fibroblast-based equivalents exhibited macroscopic contractile behaviour. In addition, eschar fibroblasts-based equivalents demonstrated higher alpha-smooth muscle actin expression on mRNA and protein levels. In conclusion, our findings suggest that eschar fibroblasts-based full skin equivalents hold promise as a platform to study burn wound environments as eschar fibroblasts are clinically more relevant fibroblasts and able to mimic certain aspects of the challenging wound environment in vitro.

The added value of cultured cells in burn treatment: A systematic review

INTRODUCTION

Advancements in resuscitative care and burn surgery have improved survival rates after extensive burn injuries, shifting focus to enhancing the quality of survival. Conventional treatment with split-thickness skin grafts (STSG) presents limitations such as donor-site morbidity, limited availability in extensive burn injuries, and hypertrophic scarring. Tissue engineering aims to address these drawbacks by developing optimal skin substitutes. This systematic review aims to provide an overview of the current applications of cultured cells in burn surgery, encompassing diverse approaches and addressing existing challenges to enhance burn wound management and improve patient outcomes.

METHODS

Following PRISMA guidelines, a comprehensive search was performed across three databases (PubMed, Embase, Cochrane Library) for articles on cultured cell use in burn treatment. Only clinical studies were included. Articles were screened by two independent reviewers. Quality assessment was performed.

RESULTS

The search yielded 167 articles, of which 14 met the eligibility criteria. The selection included 8 randomized controlled trials, 5 prospective cohort trials, and 1 retrospective cohort study. Various tissue-engineered skin substitutes, from cultured epidermal autografts to dermal regeneration templates seeded with cultured cells, showed promising outcomes. Several substitutes exhibited take rates comparable to STSG with improved scar quality.

CONCLUSION

Results are promising, though standardization of cultured skin substitutes and robust clinical trials with larger populations and appropriate comparators are still lacking.

Emerging technologies in regenerative medicine: The future of wound care and therapy

Wound healing, an intricate biological process, comprises orderly phases of simple biological processed including hemostasis, inflammation, angiogenesis, cell proliferation, and ECM remodeling. The regulation of the shift in these phases can be influenced by systemic or environmental conditions. Any untimely transitions between these phases can lead to chronic wounds and scarring, imposing a significant socio-economic burden on patients. Current treatment modalities are largely supportive in nature and primarily involve the prevention of infection and controlling inflammation. This often results in delayed healing and wound complications. Recent strides in regenerative medicine and tissue engineering offer innovative and patient-specific solutions. Mesenchymal stem cells (MSCs) and their secretome have gained specific prominence in this regard. Additionally, technologies like tissue nano-transfection enable in situ gene editing, a need-specific approach without the requirement of complex laboratory procedures. Innovating approaches like 3D bioprinting and ECM bioscaffolds also hold the potential to address wounds at the molecular and cellular levels. These regenerative approaches target common healing obstacles, such as hyper-inflammation thereby promoting self-recovery through crucial signaling pathway stimulation. The rationale of this review is to examine the benefits and limitations of both current and emerging technologies in wound care and to offer insights into potential advancements in the field. The shift towards such patient-centric therapies reflects a paradigmatic change in wound care strategies.

Cultured Skin in the Modern Era and the Impact of Infrastructure Volatility on Learning Curves: A 33-Year Institutional Review

Finding a perfect epidermal transplant remains a holy grail of burn surgery. The epidermis is a site of stem cells that allows for epithelial regeneration. The use of cultured epithelial autografts (CEA) for the treatment of major burns was first reported in 1981. CEA requires specialized skills; thus, reports from different burn centers have shown mixed results. Comparing our modern data with past data shows how this field has advanced while maintaining institutional control. We performed a retrospective analysis of all patients admitted between January 1, 1988 and December 31, 2021 for massive burns that were managed with CEA. Patients were divided into pre-defined groups: G1 (early-era) = 1988-1999, G2 (pre-modern-era) = 2000-2010, and G3 (modern-era) = 2011-2021. We compared demographics, %TBSA, presence of inhalation-injury, length of hospital stay (LOS), complications, and mortality. We treated 52 patients with CEA during the study period. In the modern-era, we found 11 patients; in the pre-modern-era, 10; and in the early-era, 31. Injury characteristics, including %TBSA and the presence of inhalation-injury, were not significantly different between the groups. We observed lower mortality rates in G1 and G3 (G1:20% vs. G2:42% vs. G3:27%, P < 0.05), although the predicted mortality was not significantly different between the groups (G1:50% vs. G2:47% vs. G3:49%, NS). Patients in G1 also had a shorter hospital LOS, in days, (G1:90 vs. G2:127 vs. G3:205, P < 0.05). Finally, the surface-area grafted per patient was the highest in G2 (G1:2,000cm2 vs. G2:4,187cm2 vs. G3:4,090cm2, P < 0.01). CEA has not gained popularity despite proven positive outcomes. Our retrospective analysis showed that CEA should be considered as a treatment option for patients with large burns, given proper training and infrastructure.

Advancements in cell-based therapies for thermal burn wounds: a comprehensive systematic review of clinical trials outcomes

BACKGROUND

Burn trauma is one of the major causes of morbidity and mortality worldwide. The standard management of burn wounds consists of early debridement, dressing changes, surgical management, and split-thickness skin autografts (STSGs). However, there are limitations for the standard management that inclines us to find alternative treatment approaches, such as innovative cell-based therapies. We aimed to systematically review the different aspects of cell-based treatment approaches for burn wounds in clinical trials.

METHODS

A systematic search through PubMed, Medline, Embase, and Cochrane Library databases was carried out using a combination of keywords, including "Cell transplantation", "Fibroblast", "Keratinocyte", "Melanocyte", or "Stem Cell" with "Burn", "Burn wound", or "Burn injury". Firstly, titles and abstracts of the studies existing in these databases until "February 2024" were screened. Then, the selected studies were read thoroughly, and considering the inclusion and exclusion criteria, final articles were included in this systematic review. Moreover, a manual search was performed through the reference lists of the included studies to minimize the risk of missing reports.

RESULTS

Overall, 30 clinical trials with 970 patients were included in our study. Considering the type of cells, six studies used keratinocytes, nine used fibroblasts, eight used combined keratinocytes and fibroblasts, one study used combined keratinocytes and melanocytes, five used combined keratinocytes and fibroblasts and melanocytes, and one study used mesenchymal stem cells (MSCs). Evaluation of the preparation type in these studies showed that cultured method was used in 25 trials, and non-cultured method in 5 trials. Also, the graft type of 17 trials was allogeneic, and of 13 other trials was autologous.

CONCLUSIONS

Our study showed that employing cell-based therapies for the treatment of burn wounds have significant results in clinical studies and are promising approaches that can be considered as alternative treatments in many cases. However, choosing appropriate cell-based treatment for each burn wound is essential and depends on the situation of each patient.

A single-center, open-labeled, randomized, 6-month, parallel-group study to assess the safety and efficacy of allogeneic cultured keratinocyte sheet transplantation for deep second-degree burn wounds: rationale and design of phase I/II clinical trial

BACKGROUND

Burn-related injuries are a major global health issue, causing 180,000 deaths per year. Early debridement of necrotic tissue in association with a split-thickness skin graft is usually administered for some of the 2nd- and 3rd-degree injuries. However, this approach can be complicated by factors such as a lack of proper donor sites. Artificial skin substitutes have attracted much attention for burn-related injuries. Keratinocyte sheets are one of the skin substitutes that their safety and efficacy have been reported by previous studies.

METHODS

Two consecutive clinical trials were designed, one of them is phase I, a non-randomized, open-label trial with 5 patients, and phase II is a randomized and open-label trial with 35 patients. A total number of 40 patients diagnosed with 2nd-degree burn injury will receive allogenic keratinocyte sheet transplantation. The safety and efficacy of allogeneic skin graft with autograft skin transplantation and conventional treatments, including Vaseline dressing and topical antibiotic, will be compared in different wounds of a single patient in phase II. After the transplantation, patients will be followed up on days 3, 7, 10, 14, 21, and 28. In the 3rd and 6th months after the transplantation scar, a wound closure assessment will be conducted based on the Vancouver Scar Scale and the Patient and Observer Scar Assessment Scale.

DISCUSSION

This study will explain the design and rationale of a cellular-based skin substitute for the first time in Iran. In addition, this work proposes this product being registered as an off-the-shelf product for burn wound management in the country.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials (IRCT) IRCT20080728001031N31, 2022-04-23 for phase I and IRCT20080728001031N36, 2024-03-15 for phase II.

Optimization of hair follicle spheroids for hair-on-a-chip

Currently, most models for hair follicle research have the limitation of not replicating some key features of the hair follicle microenvironment. To complement this, we transfected various factors for hair growth into dermal papilla cells (DPCs) by electroporation and cultured the spheroids with keratinocytes (KCs). We optimized the cell number and culture period for applying spheroids to hair-on-a-chip. Furthermore, we investigated the expression of hair growth factors in spheroids depending on the presence or absence of human umbilical vein endothelial cells (HUVECs) and transfection. In spheroids in which DPCs, KCs, and HUVECs were co-cultured for 21 days, the expression of lymphoid enhancer factor 1 (LEF1), T-cell factor 1 (TCF1), and keratin 25 (K25) in the center of the spheroid, the expression of keratin 17 (K17) on the outer surface of the spheroid, and the shape of hair extending outward from the spheroid surface were observed. From these results, it is expected that a hair-on-a-chip experiment in which short-term cultured TKH spheroids are injected into the dermis and co-cultured with KC will enable the production of full-thickness skin equivalents containing hair in vitro without transplantation into animals.

Case report of the first Caucasian burn patient transplanted with Cutimed Sorbact®-based cultured epithelial autografts technique at Tygerberg Hospital, Cape Town, South Africa: An 8-year follow-up

Cultured epithelial autograft applications are limited by the associated cost and time constraints in resource-limited settings. A modified composite technique using the patients' own tissue and Cutimed Sorbact dressing was employed as a life-saving emergency measure. Since the non-Caucasian population was more commonly treated at the center, it was important to report the first Caucasian patient outcome, as the graft-take outcome for all populations was unknown. A 54-year-old male with extensive flame burns and a low chance of survival was admitted to the Tygerberg Burn Center. He received traditional skin grafts and cultured epithelial cells, after the 2 week-culture period using the current technique. Short- (⩽2 weeks) and long-term graft take (⩽8 years) was inspected. Good graft take and complete epithelialization was observed during short-term inspection with partially healed areas initially attributed to extensive burn depth and dressing removal. Long-term follow-up indicated a near normal tissue appearance and excellent pliability.

Histological assessment of nanostructured fibrin-agarose skin substitutes grafted in burnt patients. A time-course study

A previously developed fibrin-agarose skin model-UGRSKIN-showed promising clinical results in severely burnt patients. To determine the histological parameters associated to the biocompatibility and therapeutic effects of this model, we carried out a comprehensive structural and ultrastructural study of UGRSKIN grafted in severely burnt patients after 3 months of follow-up. The grafted epidermis was analogue to native human skin from day 30th onward, revealing well-structured strata with well-differentiated keratinocytes expressing CK5, CK8, CK10, claudin, plakoglobin, filaggrin, and involucrin in a similar way to controls, suggesting that the epidermis was able to mature and differentiate very early. Melanocytes and Langerhans cells were found from day 30th onward, together with a basement membrane, abundant hemidesmosomes and lack of rete ridges. At the dermal layer, we found an interface between the grafted skin and the host tissue at day 30th, which tended to disappear with time. The grafted superficial dermis showed a progressive increase in properly-oriented collagen fibers, elastic fibers and proteoglycans, including decorin, similarly to control dermis at day 60-90th of in vivo follow-up. Blood vessels determined by CD31 and SMA expression were more abundant in grafted skin than controls, whereas lymphatic vessels were more abundant at day 90th. These results contribute to shed light on the histological parameters associated to biocompatibility and therapeutic effect of the UGRSKIN model grafted in patients and demonstrate that the bioengineered skin grafted in patients is able to mature and differentiate very early at the epithelial level and after 60-90 days at the dermal level.

In vitro comparison of human plasma-based and self-assembled tissue-engineered skin substitutes: two different manufacturing processes for the treatment of deep and difficult to heal injuries

Background

The aim of this in vitro study was to compare side-by-side two models of human bilayered tissue-engineered skin substitutes (hbTESSs) designed for the treatment of severely burned patients. These are the scaffold-free self-assembled skin substitute (SASS) and the human plasma-based skin substitute (HPSS).

Methods

Fibroblasts and keratinocytes from three humans were extracted from skin biopsies (N = 3) and cells from the same donor were used to produce both hbTESS models. For SASS manufacture, keratinocytes were seeded over three self-assembled dermal sheets comprising fibroblasts and the extracellular matrix they produced (n = 12), while for HPSS production, keratinocytes were cultured over hydrogels composed of fibroblasts embedded in either plasma as unique biomaterial (Fibrin), plasma combined with hyaluronic acid (Fibrin-HA) or plasma combined with collagen (Fibrin-Col) (n/biomaterial = 9). The production time was 46-55 days for SASSs and 32-39 days for HPSSs. Substitutes were characterized by histology, mechanical testing, PrestoBlue™-assay, immunofluorescence (Ki67, Keratin (K) 10, K15, K19, Loricrin, type IV collagen) and Western blot (type I and IV collagens).

Results

The SASSs were more resistant to tensile forces (p-value < 0.01) but less elastic (p-value < 0.001) compared to HPSSs. A higher number of proliferative Ki67+ cells were found in SASSs although their metabolic activity was lower. After epidermal differentiation, no significant difference was observed in the expression of K10, K15, K19 and Loricrin. Overall, the production of type I and type IV collagens and the adhesive strength of the dermal-epidermal junction was higher in SASSs.

Conclusions

This study demonstrates, for the first time, that both hbTESS models present similar in vitro biological characteristics. However, mechanical properties differ and future in vivo experiments will aim to compare their wound healing potential.

Pharmaceutical Prophylaxis of Scarring with Emphasis on Burns: A Review of Preclinical and Clinical Studies

Significance: The worldwide estimate of burns requiring medical attention each year is 11 million. Each year in the United States, ∼486,000 burn injuries receive medical attention, including 40,000 hospitalizations. Scars resulting from burns can be disfiguring and impair functions. The development of prophylactic drugs for cutaneous scarring could improve the outcomes for burns, traumatic lacerations (>6 million/year treated in U.S. emergency rooms), and surgical incisions (∼250 million/year worldwide). Antiscar pharmaceuticals have been estimated to have a market of $12 billion. Recent Advances: Many small molecules, cells, proteins/polypeptides, and nucleic acids have mitigated scarring in animal studies and clinical trials, but none have received Food and Drug Administration (FDA) approval yet. Critical Issues: The development of antiscar pharmaceuticals involves the identification of the proper dose, frequency of application, and window of administration postwounding for the indicated wound. Risks of infection and impaired healing must be considered. Scar outcome needs to be evaluated after scars have matured. Future Directions: Once treatments have demonstrated safety and efficacy in rodent and/or rabbit and porcine wound models, human testing can begin, such as on artificially created wounds on healthy subjects and on bilateral-surgical wounds, comparing treatments versus vehicle controls on intrapatient-matched wounds, before testing on separate cohorts of patients. Given the progress made in the past 20 years, FDA-approved drugs for improving scar outcomes may be expected.

Cellular human tissue-engineered skin substitutes investigated for deep and difficult to heal injuries

Wound healing is an important function of skin; however, after significant skin injury (burns) or in certain dermatological pathologies (chronic wounds), this important process can be deregulated or lost, resulting in severe complications. To avoid these, studies have focused on developing tissue-engineered skin substitutes (TESSs), which attempt to replace and regenerate the damaged skin. Autologous cultured epithelial substitutes (CESs) constituted of keratinocytes, allogeneic cultured dermal substitutes (CDSs) composed of biomaterials and fibroblasts and autologous composite skin substitutes (CSSs) comprised of biomaterials, keratinocytes and fibroblasts, have been the most studied clinical TESSs, reporting positive results for different pathological conditions. However, researchers' purpose is to develop TESSs that resemble in a better way the human skin and its wound healing process. For this reason, they have also evaluated at preclinical level the incorporation of other human cell types such as melanocytes, Merkel and Langerhans cells, skin stem cells (SSCs), induced pluripotent stem cells (iPSCs) or mesenchymal stem cells (MSCs). Among these, MSCs have been also reported in clinical studies with hopeful results. Future perspectives in the field of human-TESSs are focused on improving in vivo animal models, incorporating immune cells, designing specific niches inside the biomaterials to increase stem cell potential and developing three-dimensional bioprinting strategies, with the final purpose of increasing patient's health care. In this review we summarize the use of different human cell populations for preclinical and clinical TESSs under research, remarking their strengths and limitations and discuss the future perspectives, which could be useful for wound healing purposes.

Subjective Tools for Burn Scar Assessment: An Integrative Review

OBJECTIVE

To review the clinical and scientific literature on the subjective ways of assessing burn scars and describe their main characteristics.

DATA SOURCES

The Latin American, Caribbean Health Sciences Literature, Nursing Database, PubMed, CINAHL, and Scopus and Web of Science databases were used to search for studies published between 2014 and 2018 using descriptors in Portuguese, Spanish, and English.

STUDY SELECTION

After establishing the research question and the location and definition of the studies, as well as accounting for differences among databases and application of filters based on inclusion and exclusion criteria, 886 references remained.

DATA EXTRACTION

Investigators reviewed the titles and abstracts of the sample and selected 188 relevant studies for full review.

DATA SYNTHESIS

Twenty-six subjective forms of assessment were found; most research concerned the Patient and Observer Scar Assessment Scale and the Vancouver Scar Scale.

CONCLUSIONS

The Patient and Observer Scar Assessment Scale and the Vancouver Scar Scale are the most common scales for assessing burn scars and have similar evaluation points such as vascularization, pliability, pigmentation, and height, which are the main parameters that contribute to the general assessment and severity of a scar. There is a need to improve instructions for application of the scales to facilitate better understanding and improve agreement among evaluators.

Use of Autologous Skin Cell Suspension for the Treatment of Hand Burns: A Pilot Study

Purpose

Autologous skin cell suspension (ASCS) is a valid alternative and adjunct to split-thickness skin grafting (STSG) for treating burns. Limited data exists regarding the use of ASCS for hand burns. We hypothesized that using ASCS in hand burns shortens healing time with no difference in complications and less donor site morbidity.

Methods

This was a retrospective chart review of second- and third-degree hand burns treated at a level 1 Trauma and Burn Center from 2017 to 2019. Study groups included patients with hand burns treated with ASCS in combination with STSG and those treated with STSG alone. Outcomes included time to re-epithelialization, return to work, length of hospital stay, and complications including reoperation, graft failure, and infection.

Results

Fifty-nine patients aged 14 to 85 years (mean age 39 ± 15 years) met inclusion criteria. The ASCS treatment group comprised 37 patients; STSG comprised 22 patients. Mean follow-up time was 14 ± 7 months. The ASCS treatment group had a larger mean percent total body surface area (TBSA) (22% ± 14% vs 6% ± 8%; P < .05). There was no difference in time to wound re-epithelialization between both groups (ASCS, 11 ± 4 days vs STSG, 11 ± 5 days). Mean length-of-stay was 23 ± 13 days compared to 10 ± 13 days (P < .05) between the ASCS and STSG groups, respectively. No patients in the ASCS group required reoperation, whereas 2 patients in the STSG group required such for an infection-related graft loss and a web space contracture release. On multivariable analysis adjusting for TBSA, ASCS was associated with an earlier return to work (P < .05).

Conclusions

ASCS is safe and effective in treating hand burns. ASCS was associated with similar rates of re-epithelialization, earlier return to work, and no difference in complications compared with STSG.

Type of study/level of evidence: Therapeutic IV.

Historical Evolution of Skin Grafting-A Journey through Time

Autologous skin grafting was developed more than 3500 years ago. Several approaches and techniques have been discovered and established in burn care since then. Great achievements were made during the 19th and 20th century. Many of these techniques are still part of the surgical burn care. Today, autologous skin grafting is still considered to be the gold standard for burn wound coverage. The present paper gives an overview about the evolution of skin grafting and its usage in burn care nowadays.

Determining clinically meaningful thresholds for innovative burn care products to reduce autograft: A US burn surgeon Delphi panel

Reducing the amount of donor skin needed for definitive wound closure can improve outcomes in patients with severe burns. This Delphi Consensus Panel (DCP) aimed to achieve expert consensus on the percentage reduction in donor skin for autograft that constitutes a clinically meaningful benefit. A two-round DCP of fifteen US burn surgeons was conducted via a web-based survey platform. Fourteen panelists (93.3%) completed both rounds. In Round 2, consensus, defined as ≥70% agreement, was achieved for five of the seven consensus statements. All panelists agreed that a clinically meaningful reduction in the amount of donor skin required would facilitate wound management and decrease donor site morbidity experienced by patients. Furthermore, based on three treatment scenarios, consensus was achieved for a clinically meaningful reduction in the amount of donor skin required for autograft for the adult population in deep partial-thickness and full-thickness burns. Findings from this DCP indicate that an innovative cellular and/or tissue product that would reduce the needed amount of donor skin, by the identified thresholds, has the potential to improve the outcomes for patients with severe burn injuries in a meaningful way.

Human serum albumin as a clinically accepted cell carrier solution for skin regenerative application

The rules governing Medicinal Products in the European Union necessitates the production of cell-based therapy in good manufacturing practice facilities. The produced cells may need several hours in transportation to reach the application sites. In this study, we investigated four candidate solutions for transporting human keratinocytes. The solutions are (1) normal saline, (2) saline with 2.5% human serum albumin (Saline + HSA), (3) chemically defined, xeno-free keratinocyte media and (4) keratinocyte media with pituitary bovine extract (PBE-media). One million keratinocytes from three donors were suspended in each solution and kept at 4 °C for up to 24 h. Cells kept in Saline + HSA showed higher viability after 1, 3 and 24 h. Then, equal number of viable cells were seeded on collagenous matrix and cultured for 48 h. The adhesion and colonization were higher in the cells kept in PBE-media, while the keratinocyte surface marker, cytokeratin 14, was present in all studied groups. These results confirmed the suitability of Saline + HSA as a cell transportation solution for clinical use, which will be the choice for the planned clinical trial. Keratinocyte PBE-media can be an alternative for cells transported for research purpose, if the same media type is going to be used in the following experiments.

Vascularization is the next challenge for skin tissue engineering as a solution for burn management

Skin regeneration represents a promising line of management for patients with skin loss, including burn victims. The current approach of spraying single cells over the defective areas results in variable success rates in different centers. The modern approach is to synthesize a multilayer skin construct that is based on autologous stem cells. One of the main complications with different types of transplants is sloughing due to the absence of proper vascularization. Ensuring proper vascularization will be crucial for the integration of skin constructs with the surrounding tissues. Combination of the right cells with scaffolds of proper physico-chemical properties, vascularization can be markedly enhanced. The material effect, pore size and adsorption of certain proteins, as well as the application of appropriate growth factors, such as vascular endothelial growth factors, can have an additive effect. A selection of the most effective protocols is discussed in this review.

Reconstructed human skin shows epidermal invagination towards integrated neopapillae indicating early hair follicle formation in vitro

Application of reconstructed human Skin (RhS) is a promising approach for the treatment of extensive wounds and for drug efficacy and safety testing. However, incorporating appendages, such as hair follicles, into RhS still remains a challenge. The hair follicle plays a critical role in thermal regulation, dispersion of sweat and sebum, sensory and tactile functions, skin regeneration, and repigmentation. The aim of this study was to determine whether human neopapilla could be incorporated into RhS (differentiated epidermis on fibroblast and endothelial cell populated dermis) and whether the neopapillae maintain their inductive follicular properties in vitro. Neopapillae spheroids, constructed from expanded and self‐aggregating dermal papilla cells, synthesized extracellular matrix typically found in follicular papillae. Compared with dermal fibroblasts, neopapillae showed increased expression of multiple genes (Wnt5a, Wnt10b, and LEF1) known to regulate hair development and also increased secretion of CXCL1, which is a strong keratinocyte chemoattractant. When neopapillae were incorporated into the dermis of RhS, they stimulated epidermal down‐growth resulting in engulfment of the neopapillae sphere. Similar to the native hair follicle, the differentiated invaginating epidermis inner side was keratin 10 positive and the undifferentiated outer side keratin 10 negative. The outer side was keratin 15 positive confirming the undifferentiated nature of these keratinocytes aligning a newly formed collagen IV, laminin V positive basement membrane within the hydrogel. In conclusion, we describe a RhS model containing neopapillae with hair follicle‐inductive properties. Importantly, epidermal invagination occurred to engulf the neopapillae, thus demonstrating in vitro the first steps towards hair follicle morphogenesis in RhS.

KLF4 inhibition promotes the expansion of keratinocyte precursors from adult human skin and of embryonic-stem-cell-derived keratinocytes

Expanded autologous skin keratinocytes are currently used in cutaneous cell therapy, and embryonic-stem-cell-derived keratinocytes could become a complementary alternative. Regardless of keratinocyte provenance, for efficient therapy it is necessary to preserve immature keratinocyte precursors during cell expansion and graft processing. Here, we show that stable and transient downregulation of the transcription factor Krüppel-like factor 4 (KLF4) in keratinocyte precursors from adult skin, using anti-KLF4 RNA interference or kenpaullone, promotes keratinocyte immaturity and keratinocyte self-renewal in vitro, and enhances the capacity for epidermal regeneration in mice. Both stable and transient KLF4 downregulation had no impact on the genomic integrity of adult keratinocytes. Moreover, transient KLF4 downregulation in human-embryonic-stem-cell-derived keratinocytes increased the efficiency of skin-orientated differentiation and of keratinocyte immaturity, and was associated with improved generation of epidermis. As a regulator of the cell fate of keratinocyte precursors, KLF4 could be used for promoting the ex vivo expansion and maintenance of functional immature keratinocyte precursors.

Skin substitutes are more potent than dermal or epidermal substitutes in stimulating endothelial cell sprouting

Background

Therapy resistant ulcers are wounds that remain open for a long time period and often arise from chronic venous disease, prolonged pressure or diabetes. For healing of chronic wounds, revitalization of the inert wound bed, which is achieved by angiogenic sprouting of new blood vessels is of great importance. An alternative treatment option to conventional therapies is the use of skin substitutes: dermal (DS), epidermal (ES) or bi-layered skin substitutes (SS). The aim of this study was to determine the mode of action of an autologous SS, ES and DS with regards to endothelial cell proliferation, migration and angiogenic sprouting into a fibrin hydrogel.

Results

SS consists of a fully differentiated epidermis expanding over the acellular donor dermis (AD) which has become repopulated with fibroblasts. DS is the same construct as SS but without the epidermis and ES is the same construct as SS but without the fibroblasts. As a control, AD was used throughout. It was found that the bi-layered SS was the most potent substitute in inducing migration and sprouting of endothelial cells. The cross talk between dermis and epidermis resulted in the strongest induction of sprouting via VEGF and uPAR. ES stimulated sprouting more than DS again via VEGF and uPAR. The slight induction of sprouting mediated by DS was not mediated by VEGF, but was in part stimulated through uPAR.

Conclusion

This in vitro study supports our clinical observations that a bi-layered SS is a strong stimulator of angiogenesis and therefore has the potential to revitalize an inert wound bed.

Human saliva stimulates skin and oral wound healing in vitro

Despite continuous exposure to environmental pathogens, injured mucosa within the oral cavity heals faster and almost scar free compared with skin. Saliva is thought to be one of the main contributing factors. Saliva may possibly also stimulate skin wound healing. If so, it would provide a novel therapy for treating skin wounds, for example, burns. This study aims to investigate the therapeutic wound healing potential of human saliva in vitro. Human saliva from healthy volunteers was filter sterilized before use. Two different in vitro wound models were investigated: (a) open wounds represented by 2D skin and gingiva cultures were used to assess fibroblast and keratinocyte migration and proliferation and (b) blister wounds represented by introducing freeze blisters into organotypic reconstructed human skin and gingiva. Re‐epithelialization and differentiation (keratin K10, K13, K17 expression) under the blister and inflammatory wound healing mediator secretion was assessed. Saliva‐stimulated migration of skin and oral mucosa fibroblasts and keratinocytes, but only fibroblast proliferation. Topical saliva application to the blister wound on reconstructed skin did not stimulate re‐epithelization because the blister wound contained a dense impenetrable dead epidermal layer. Saliva did promote an innate inflammatory response (increased CCL20, IL‐6, and CXCL‐8 secretion) when applied topically to the flanking viable areas of both wounded reconstructed human skin and oral mucosa without altering the skin specific keratin differentiation profile. Our results show that human saliva can stimulate oral and skin wound closure and an inflammatory response. Saliva is therefore a potential novel therapeutic for treating open skin wounds.

The Effect of Enzymatic Digestion on Cultured Epithelial Autografts

Severe burns are often treated by means of autologous skin grafts, preferably following early excision of the burnt tissue. In the case of, for example, a large surface trauma, autologous skin cells can be expanded in vitro prior to transplantation to facilitate the treatment when insufficient uninjured skin is a limitation. In this study we have analyzed the impact of the enzyme (trypsin or accutase) used for cell dissociation and the incubation time on cell viability and expansion potential, as well as expression of cell surface markers indicative of stemness. Skin was collected from five individuals undergoing abdominal reduction surgery and the epidermal compartment was digested in either trypsin or accutase. Trypsin generally generated more cells than accutase and with higher viability; however, after 7 days of subsequent culture, accutase-digested samples tended to have a higher cell count than trypsin, although the differences were not significant. No significant difference was found between the enzymes in median fluorescence intensity of the analyzed stem cell markers; however, accutase digestion generated significantly higher levels of CD117- and CD49f-positive cells, but only in the 5 h digestion group. In conclusion, digestion time appeared to affect the isolated cells more than the choice of enzyme.

The discovery and development of topical medicines for wound healing

INTRODUCTION

Chronic, nonhealing skin wounds claim >3% of the health-care budget in industrialized countries, and the incidence is rising. Currently, two parallel trends influence innovations within the field of wound healing: the need to reduce spread of antibiotic resistance and the emerging use of health economy and value-based models. Areas covered: This review focuses on the discovery of drug candidates and development of treatments aiming to enhance wound healing in the heterogeneous group of patients with nonhealing wounds. Expert opinion: Nonhealing wounds are multifaceted and recognized as difficult indications. The majority of products currently in use are medical device dressings, or concepts of negative pressure or hyperbaric oxygen treatment. Global best practice guidelines for the treatment of diabetic foot ulcers recommend debridement, redressing, as well as infection control, and are critical to the lack of coherent clinical evidence for many approved products in active wound care. To accelerate wound healing, there is an emerging trend toward biologics, gene therapy, and novel concepts for drug delivery in research and in the pipeline for clinical trials. Scientific delineation of the therapeutic mechanism of action is, in our opinion, vital for clinical trial success and for an increased fraction of medical products in the pharmaceutical pipeline.

Review of Modern Techniques for the Assessment of Skin Hydration

Skin hydration is a complex process that influences the physical and mechanical properties of skin. Various technologies have emerged over the years to assess this parameter, with the current standard being electrical probe-based instruments. Nevertheless, their inability to provide detailed information has prompted the use of sophisticated spectroscopic and imaging methodologies, which are capable of in-depth skin analysis that includes structural and composition details. Modern imaging and spectroscopic techniques have transformed skin research in the dermatological and cosmetics disciplines, and are now commonly employed in conjunction with traditional methods for comprehensive assessment of both healthy and pathological skin. This article reviews current techniques employed in measuring skin hydration, and gives an account on their principle of operation and applications in skin-related research.

Systematic review of clinical outcome reporting in randomised controlled trials of burn care

INTRODUCTION

Systematic reviews collate trial data to provide evidence to support clinical decision-making. For effective synthesis, there must be consistency in outcome reporting. There is no agreed set of outcomes for reporting the effect of burn care interventions. Issues with outcome reporting have been identified, although not systematically investigated. This study gathers empirical evidence on any variation in outcome reporting and assesses the need for a core outcome set for burn care research.

METHODS

Electronic searches of four search engines were undertaken from January 2012 to December 2016 for randomised controlled trials (RCTs), using medical subject headings and free text terms including 'burn', 'scald' 'thermal injury' and 'RCT'. Two authors independently screened papers, extracted outcomes verbatim and recorded the timing of outcome measurement. Duplicate outcomes (exact wording ± different spelling), similar outcomes (albumin in blood, serum albumin) and identical outcomes measured at different times were removed. Variation in outcome reporting was determined by assessing the number of unique outcomes reported across all included trials. Outcomes were classified into domains. Bias was reduced using five researchers and a patient working independently and together.

RESULTS

147 trials were included, of which 127 (86.4%) were RCTs, 13 (8.8%) pilot studies and 7 (4.8%) RCT protocols. 1494 verbatim clinical outcomes were reported; 955 were unique. 76.8% of outcomes were measured within 6 months of injury. Commonly reported outcomes were defined differently. Numbers of unique outcomes per trial varied from one to 37 (median 9; IQR 5,13). No single outcome was reported across all studies demonstrating inconsistency of reporting. Outcomes were classified into 54 domains. Numbers of outcomes per domain ranged from 1 to 166 (median 11; IQR 3,24).

CONCLUSIONS

This review has demonstrated heterogeneity in outcome reporting in burn care research which will hinder amalgamation of study data. We recommend the development of a Core Outcome Set.

PROSPERO REGISTRATION NUMBER

CRD42017060908.

Platelet-rich plasma lyophilization enables growth factor preservation and functionality when compared with fresh platelet-rich plasma

Aims: To compare levels and activity of the growth factors between fresh and lyophilized platelet-rich plasma (PRP). Methods: Analysis of platelet concentration using fibroblast and human umbilical vein endothelial cell cultures were compared between fresh and lyophilized PRP obtained from peripheral blood. Results: After lyophilization, 54% of platelets were intact whereas the fresh showed no aggregation with agonists (levels under 20%). The concentration of growth factors (VEGF, EGF, TGF-β and PDGF) in both products were similar. Fresh and lyophilized PRPs induced proliferation in the fibroblasts at 24 h (0.303 vs 0.300, respectively). Conclusion: Lyophilized PRP appears to be an alternative to fresh PRP and the results evidenced the role of growth factors as a key element in the activity of this product.

The Benefit of Microskin in Combination With Autologous Keratinocyte Suspension to Treat Full Skin Loss In Vivo

Patients with extensive deep burns often lack enough autologous skin to cover the wounds. This study explores a new method using microskin in combination with autologous keratinocytes in the treatment of extensive deep burn. Wounds in the combination group were treated with automicroskin at an area expansion ratio of 20:1 (wound area to automicroskin area) and autologous keratinocyte suspension, which were compared with the following treatments: no autotransplant, only allografts (control group); autologous keratinocyte suspension only (keratinocyte only group); automicroskin at an area expansion ratio of 20:1 (20:1 group); and automicroskin at an area expansion ratio of 10:1 (10:1 group, positive control). The authors used epithelialization rate (epithelialized area on day 21 divided by original wound area), hematoxylin and eosin staining, laminin, and type IV collagen immunohistochemistry to assess wound healing. The epithelialization rate of combination group (74.2% ± 8.0%) was similar to that of 10: 1 group (84.3% ± 11.9%, P = .085) and significantly (P < .05) higher than that of 20:1 group (59.2% ± 10.8%), keratinocyte only group (53.8% ± 11.5%), and control group (22.7% ± 5.5%). The hematoxylin and eosin staining and immunohistochemistry showed the epithelialization in the combination group was better than that in the keratinocyte only group and control group. Microskin in combination with autologous keratinocyte suspension can promote the reepithelialization of full-thickness wounds and reduce the requirements for automircoskin, and it is a useful option in the treatment of extensive deep burns.

Ten-year follow-up of a case of necrotizing fasciitis successfully treated with negative-pressure wound therapy, dermal regeneration template application, and split- thickness skin autograft

INTRODUCTION

Necrotizing fasciitis is a rapidly progressive and often fatal infection of the fasciae and subcutaneous tissues.

PATIENT AND METHODS

In this case report, we present the treatment of a 63-year-old patient suffering from diabetes mellitus, who was admitted to the emergency unit for severe right gluteal pain, which had begun 24 hours before admission. Cutaneous symptoms, oliguria, metabolic acidosis, acute renal failure, severe hypotension, and tachycardia occurred, and the patient was admitted to Intensive Care a few hours after initial admission. The patient underwent a debridement of gluteal, abdominal, lower-thoracic, and upper thigh regions. Biopsy of fascia lata confirmed the suspected diagnosis of necrotizing fasciitis. Treatment included prompt surgical debridement, negative-pressure wound therapy, and dermal regeneration template application with fibrin glue, and subsequent split-thickness skin autografting.

RESULTS

After 10 years, elasticity of the skin and limb mobility are comparable to that in non-injured areas, and the patient is pain free.

CONCLUSION

In our opinion, this combination should be a treatment of choice for large wounds in the patients with NF with multiple comorbidities.

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.

Novel Application of Cultured Epithelial Autografts (CEA) with Expanded Mesh Skin Grafting Over an Artificial Dermis or Dermal Wound Bed Preparation

Cultured epithelial autografts (CEA) with highly expanded mesh skin grafts were used for extensive adult burns covering more than 30% of the total body surface area. A prospective study on eight patients assessed subjective and objective findings up to a 12-month follow-up. The results of wound healing for over 1:6 mesh plus CEA, gap 1:6 mesh plus CEA, and 1:3 mesh were compared at 3, 6, and 12 months using extensibility, viscoelasticity, color, and transepidermal water loss by a generalized estimating equation (GEE) or generalized linear mixed model (GLMM). No significant differences were observed among the paired treatments at any time point. At 6 and 12 months, over 1:6 mesh plus CEA achieved significantly better expert evaluation scores by the Vancouver and Manchester Scar Scales (p < 0.01). Extended skin grafting plus CEA minimizes donor resources and the quality of scars is equal or similar to that with conventional low extended mesh slit-thickness skin grafting such as 1:3 mesh. A longitudinal analysis of scars may further clarify the molecular changes of scar formation and pathogenesis.

Pathophysiologic Mechanisms and Current Treatments for Cutaneous Sequelae of Burn Wounds

Burn injuries are a pervasive clinical problem. Extensive thermal trauma can be life-threatening or result in long-lasting complications, generating a significant impact on quality of life for patients as well as a cost burden to the healthcare system. The importance of addressing global or systemic issues such as resuscitation and management of inhalation injuries is not disputed but is beyond the scope of this review, which focuses on cutaneous pathophysiologic mechanisms for current treatments, both in the acute and long-term settings. Pathophysiological mechanisms of burn progression and wound healing are mediated by highly complex cascades of cellular and biochemical events, which become dysregulated in slow-healing wounds such as burns. Burns can result in fibroproliferative scarring, skin contractures, or chronic wounds that take weeks or months to heal. Burn injuries are highly individualized owing to wound-specific differences such as burn depth and surface area, in addition to patient-specific factors including genetics, immune competency, and age. Other extrinsic complications such as microbial infection can complicate wound healing, resulting in prolonged inflammation and delayed re-epithelialization. Although mortality is decreasing with advancements in burn care, morbidity from postburn deformities continues to be a challenge. Optimizing specialized acute care and late burn outcome intervention on a patient-by-patient basis is critical for successful management of burn wounds and the associated pathological scar outcome. Understanding the fundamentals of integument physiology and the cellular processes involved in wound healing is essential for designing effective treatment strategies for burn wound care as well as development of future therapies. Published 2018. Compr Physiol 8:371-405, 2018.

Indications and Predictors for Reconstructive Surgery After Hand Burns

PURPOSE

The objective of this study was to analyze the prevalence, indications, and type of reconstructive surgery and predictors of the outcomes of reconstructive surgery after hand burns.

METHODS

A retrospective cohort study was conducted that included all patients admitted with acute hand burns in the Dutch burn centers from January 1998 through December 2002. The details of reconstruction including frequency, timing, indication, and techniques were collected over a 10-year follow-up period.

RESULTS

Hand burns were seen in 42% (n = 562 of 1,334) of all patients admitted with acute burns. Reconstructive surgery during the 10-year follow-up period was required in 15%. Contractures, especially of the first web space and little finger, were the most frequent indications for reconstructive surgery. Web spaces 1 to 3 and the little finger were the location most frequently operated on. The most frequently performed surgical technique was release of the contractures and the use of a random flap. Eighty percent of the reconstructive surgery patients required more than 1 reconstructive procedure, most often within 2 years of the initial injury. Secondary operations at the same location were required in 12%. In 40% of the patients, the first reconstructive surgery was performed within the first postburn year. Significant independent factors related to the need for reconstructive hand surgery were a larger area of full-thickness burns and surgical treatment of the hand during the acute phase.

CONCLUSIONS

Reconstructive surgery was required in 15% of patients who sustained hand burns. The majority of the patients requiring reconstructive surgery of the hand needed 2 or more operations to correct the contractures of the hand. Contractures of the little finger and first web space were the locations most frequently operated on. Patients with more extensive burns and who required hand surgery during the acute phase were more likely to need reconstructive surgery.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

Comparison of advanced therapy medicinal product gingiva and skin substitutes and their in vitro wound healing potentials

Skin and oral mucosa substitutes are a therapeutic option for closing hard‐to‐heal skin and oral wounds. Our aim was to develop bi‐layered skin and gingiva substitutes, from 3 mm diameter biopsies, cultured under identical conditions, which are compliant with current European regulations for advanced therapy medicinal products. We present in vitro mode of action methods to (i) determine viability: epithelial expansion, proliferation (Ki‐67), metabolic activity (MTT assay); (ii) characterize skin and gingiva substitutes: histology and immunohistochemistry; and (iii) determine potency: soluble wound healing mediator release (enzyme‐linked immunosorbent assay). Both skin and gingiva substitutes consist of metabolically active autologous reconstructed differentiated epithelium expanding from the original biopsy sheet on a fibroblast populated connective tissue matrix (donor dermis). Gingival epithelium expanded 1.7‐fold more than skin epithelium during the 3 week culture period. The percentage of proliferating Ki‐67‐positive cells located in the basal layer of the gingiva substitute was >1.5‐fold higher than in the skin substitute. Keratins 16 and 17, which are upregulated during normal wound healing, were expressed in both the skin and gingiva substitutes. Notably, the gingiva substitute secreted higher amounts of key cytokines involved in mitogenesis, motogenesis and chemotaxis (interleukin‐6 > 23‐fold, CXCL8 > 2.5‐fold) as well as higher amounts of the anti‐fibrotic growth factor, hepatocyte growth factor (>7‐fold), compared with the skin substitute. In conclusion, while addressing the viability, characterization and potency of the tissue substitutes, important intrinsic differences between skin and gingiva were discovered that may explain in part the superior quality of wound healing observed in the oral mucosa compared with skin.

Epidermal grafting for wound healing: a review on the harvesting systems, the ultrastructure of the graft and the mechanism of wound healing

Epidermal grafting for wound healing involves the transfer of the epidermis from a healthy location to cover a wound. The structural difference of the epidermal graft in comparison to the split-thickness skin graft and full-thickness skin graft contributes to the mechanism of effect. While skin grafting is an epidermal transfer, little is known about the precise mechanism of wound healing by epidermal graft. This paper aims to explore the evolution of the epidermal graft harvesting system over the last five decades, the structural advantages of epidermal graft for wound healing and the current hypotheses on the mechanism of wound healing by epidermal graft. Three mechanisms are proposed: keratinocyte activation, growth factor secretion and reepithelialisation from the wound edge. We evaluate and explain how these processes work and integrate to promote wound healing based on the current in vivo and in vitro evidence. We also review the ongoing clinical trials evaluating the efficacy of epidermal graft for wound healing. The epidermal graft is a promising alternative to the more invasive conventional surgical techniques as it is simple, less expensive and reduces the surgical burden for patients in need of wound coverage.