Negative-pressure wound therapy combined with artificial dermis (Terudermis) followed by split-thickness skin graft might be an effective treatment option for wounds exposing tendon and bone: A retrospective observation study.

ABSTRACT: Skin grafts are not suitable for closing tendon- or bone-exposing wounds, which require flap surgery. Dermal regeneration templates have value for closing such wounds, but the disadvantages of the technique include implantation failures because of infection, hematoma formation, or inappropriate immobilization. Negative-pressure wound therapy was reported to increase graft acceptance in difficult wounds.This retrospective case series of 65 patients evaluated negative-pressure therapy combined with artificial dermis for the treatment of acute or chronic tendon- or bone-exposing wounds. The artificial dermis was placed after adequate wound-bed preparation, with simultaneous application of a vacuum-assisted closure system. Split-thickness skin grafting was performed after the implanted artificial dermis had become established.The overall success rate was 88.1% (59/67): 88.6% (39/44) in the chronic wounds group and 87% (20/23) in the acute-trauma group separately. The overall mean survival time of artificial dermis in success cases was 13.24 ±â€Š7.14 days. In separately, the survival time of artificial dermis had no statistically difference in chronic wound group (13.64 ±â€Š7.53 vs 12.60 ±â€Š5.86. P = .943), but had significant statistical difference in acute trauma group (12.45 ±â€Š6.44 days vs 23.33 ±â€Š4.04 days, P = .018). Also, comorbidity of PAOD was found a strong risk factor of failure in chronic wound group (100% vs 23.1%, P < 0.001).We concluded that artificial dermis combined with negative-pressure therapy followed by split-thickness skin grafting might be a reliable and effective option for surgical reconstruction of tendon- or bone-exposing wounds, and could decreasing waiting periods of autologous skin graft.

Navigating the Regulatory Pathways and Requirements for Tissue-Engineered Products in the Treatment of Burns in the United States.

In the burn treatment landscape, a variety of skin substitutes, human tissue-sourced products, and other products are being developed based on tissue engineering (ie, the combination of scaffolds, cells, and biologically active molecules into functional tissue with the goal of restoring, maintaining, or improving damaged tissue or whole organs) to provide dermal replacement, prevent infection, or prevent or mitigate scarring. Skin substitutes can have a variety of compositions (cellular vs acellular), origins (human, animal, or synthetically derived), and complexities (dermal or epidermal only vs composite). The regulation of tissue-engineered products in the United States occurs by one of several pathways established by the U.S. Food and Drug Administration, including a Biologics License Application (BLA), a 510(k) (Class I and Class II devices), Premarket Approval (Class III devices), or a human cells, tissues, and cellular and tissue-based products designation. Key differentiators among these regulatory classifications include the amount and type of data required to support a filing. For example, a BLA requires a clinical trial(s) and evaluation of safety and efficacy by the Center for Biologics Evaluation and Research. Applicable approved biological products must also comply with submission of advertising and promotional materials per regulations. This review provides a description of, and associated requirements for, the various regulatory pathways for the approval or clearance of tissue-engineered products. Some of the regulatory challenges for commercialization of such products for the treatment of burns will be explored.

Evaluation of a cross-linked versus non-cross-linked collagen matrix in full-thickness skin defects.

Autologous skin transplantation is the gold standard for treatment of full-thickness skin defects such as deep burn injuries, but has the disadvantages of limited donor sites and donor site morbidities. Alternative skin replacement products, such as xenografts and allografts, are not a permanent solution. Numerous manufactured skin substitutes already show promising approaches, but have limited efficacy. Therefore, wound dressings adaptable to the physiology of wound healing are still needed. In a randomized controlled in vivo study, a newly designed biocompatible collagen nonwoven matrix was compared to the Integra® bilayer dermal substitute and untreated controls in 48 full-thickness skin defects in a swine model. The take of all templates was complete, and all the tissue-engineered products accelerated dermal wound healing compared to the untreated controls, as identified by planimetric measurements. The higher collagen dose treatments and Integra®-covered wounds developed the thickest, cell-rich neoepidermal tissue in histological examination. The innovative biocompatible collagen matrix is flexibly applicable and modifiable, and offers potential as a carrier membrane for therapeutic supplemental products such as growth factors to further develop effective wound dressings.

Evaluation of Wound Closure Rates Using a Human Fibroblast-derived Dermal Substitute Versus a Fetal Bovine Collagen Dressing: A Retrospective Study.

Diabetic foot ulcers (DFUs) are associated with an increased risk for serious and costly outcomes such as osteomyelitis, amputation, and hospitalization. PURPOSE: A retrospective study was conducted to evaluate the proportion of patients healed and time to healing of DFUs treated with a human fibroblast-derived dermal substitute (HFDS) or a fetal bovine collagen dressing (FBCD). METHODS: Data from patients with a DFU who received the first treatment in 2014 were extracted from the electronic record database of 93 wound care centers. Baseline demographics (eg, age, gender, body mass index, and number of wounds); wound location, size, and duration; and wound-specific information such as wound size and number of and interval between applications were obtained. Study criteria stipulated patients who received at least one treatment in 2014 with HFDS or FBCD on a DFU with location coded as foot, toe, heel, metatarsal head, toe web space, toe amputation site, or transmetatarsal amputation site; ulcer size ≥1 cm2 to <20 cm2; and ulcer area reduction ≤50% in the 28 days before the first treatment with HFDS or FBCD were eligible for inclusion. Wounds that received an alternate skin substitute treatment up to 28 days before or concurrent with the first HFDS or FBCD treatment or if patient data that lacked baseline or follow-up wound area measurement were excluded. Deidentified data were extracted directly into data files and transferred to a third-party data management and statistical group for analysis. The frequency of DFUs achieving wound closure (defined as area ≤0.25 cm2) by weeks 12 and 24 and median time to wound closure of wounds that healed were analyzed. Baseline characteristics were compared using 2-sample t tests for continuous variables and 2-tailed Fisher's exact tests for difference in proportions between treatments. Frequency of and median time to wound closure were determined by Cox proportional hazards analysis. The frequency of wounds closed at 12 and 24 weeks, median time to wound closure, hazard ratio with 95% confidence interval, and P value were estimated from the Cox model. Statistical significance was defined as P <.05. RESULTS: Records showed 206 patients with 208 DFUs received treatment (108 HFDS, mean age 60.2 years, mean wound duration 8.8 months; 100 FBCD, mean age 65.2 years, mean wound duration 12.8 months) and were included. Mean number of treatment applications was 4.5 and 2.4 for HFDS and FBCD, respectively. After 12 and 24 weeks 44 (41%) and 69 (64%) of HFDS-treated wounds, respectively, and 21 (21%) and 43 (43%) of FBCD-treated wounds, respectively, were healed (at 12 weeks, P = .03; at 24 weeks, P = .03, log rank 2-tailed test, unadjusted). Median time to wound closure for HFDS and FBCD was 14.6 and 25 weeks, respectively (P = .03; log rank, 2-tailed test; Kaplan-Meier analysis). HFDS treatment significantly increased the probability of wound healing compared to FBCD treatment in the Cox proportional hazards analysis after adjusting for treatment terms, baseline wound area, baseline wound duration, baseline wound depth, wound location, and patient age at first treatment (HR = 1.77; 95% CI: 1.06-2.97; P = .03). CONCLUSION: DFU wounds are more likely to heal when treated with HFDS than with FBCD as used by facilities in this database. Studies examining the efficacy, cost-effectiveness, and patient-centered outcomes of these treatments is warranted. .

Elaboração, desenvolvimento e instalação do primeiro banco de pele animal no Brasil para o tratamento de queimaduras e feridas / Elaboration, development, and installation of the first animal skin bank in Brazil for the treatment of burns and wounds

Introdução: A produção e a distribuição de pele humana pelos Bancos de Pele do Brasil é insuficiente para atender a demanda do país, suprindo menos de 1% da necessidade para tratar as vítimas de queimaduras. O objetivo do trabalho foi apresentar a elaboração e o desenvolvimento da implantação do primeiro Banco de Pele Animal do Brasil para tratamento da queimadura. Métodos: Trata-se de um estudo metodológico. O Banco de Pele Animal Aquático foi elaborado, desenvolvido e instalado a partir do desenvolvimento do processamento de pele da tilápia, da revisão sistemática de estudos referentes a banco de pele animal, de visitas à pscicultura em Jaguaribara-CE, da visita técnica aos bancos de pele humana no Brasil, de consulta técnica e de treinamento no Banco de Pele de Recife, da observação de todas as fases de processamento da pele de tilápia e da identificação da estrutura física da área onde ocorrem todos os processos. Resultados: Além da produção e da distribuição da pele da tilápia para os estudos em vítima de queimaduras, o banco está processando mais de 5000 peles de tilápia e encontra-se em fase de distribuição desta pele para estudos multicêntricos em outros estados e outras especialidades, que desenvolvem pesquisas nas áreas de ginecologia, ortopedia, endoscopia, estomaterapia, cirurgia vascular, odontologia e veterinária. Conclusão: este trabalho possibilitou a elaboração, o desenvolvimento e a implementação do primeiro Banco de Pele Animal do país e o primeiro Banco de Pele Aquática do mundo.

Introduction: The production and distribution of human skin by Brazilian skin banks is insufficient to meet the country's demand, supplying less than 1% of the need for treating burn victims. The objective of this work was to present the elaboration and development of the first animal skin bank of Brazil for the treatment of burns. Methods: This methodological study elaborated, developed, and installed The Aquatic Animal Skin Bank in terms of the development of tilapia skin processing after a systematic review of studies referring to animal skin banks based on visits to the pisciculture center in Jaguaribara-CE, technical visits to human skin banks in Brazil, technical consultation and training in the Recife Skin Bank, the observation of all phases of tilapia skin processing, and the identification of the physical structure of the area where the processes occur. Results: In addition to the production and distribution of tilapia skin for studies on burn victims, the bank is processing more than 5000 tilapia skin samples and is in the distribution phase of this skin for multicentric studies in other states and specialties including gynecology, orthopedics, endoscopy, stomatherapy, vascular surgery, dentistry, and veterinary medicine. Conclusion: This work enabled the elaboration, development, and implementation of Brazil's first animal skin bank and the world's first aquatic skin bank.

Artificial skin through super-sensing method and electrical impedance data from conductive fabric with aid of deep learning.

Sense of touch is a major part of man's communication with their environment. Artificial skins can help robots to have the same sense of touch, especially for their social interactions. This paper presents a pressure mapping sensing using piezo-resistive fabric to represent aspects of the sense of touch. In past few years' electrical impedance tomography (EIT) is considered to be able offer a good alternative for artificial skin in particular for its ease of adaptation for large area skin compared to individual matrix based sensors. The EIT has also very good temporal performance in data collection allowing for monitoring of fast responses to touch stimulation, enabling a truly real time touch sensing. Electromechanical responses of a conductive fabric can be exploited using EIT to create a low cost and large area touch sensing. Such electromechanical properties are often very complex, so to improve the imaging resolution and touch visibility an artificial intelligent (AI) was used in addition to the state of the art spatio-temporal imaging algorithm. This work demonstrates a step towards an integrated seamless skin with large area sensing in dynamical settings, closer to natural human skin's behaviour. For the first time a dynamical touch sensing are studies by means of a spatio-temporal based electrical impedance tomography (EIT) imaging on a conductive fabric. The experimental results demonstrated the successful results by a combined AI with dynamical EIT imaging results in single and multiple points of touch.

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.

Platelet-rich plasma with keratinocytes and fibroblasts enhance healing of full-thickness wounds.

Advances in tissue engineering led to the development of various tissue-engineered skin substitutes (TESS) for the treatment of skin injuries. The majority of the autologous TESS required lengthy and costly cell expansion process to fabricate. In this study, we determine the possibility of using a low density of human skin cells suspended in platelet-rich plasma (PRP)-enriched medium to promote the healing of full-thickness skin wounds. To achieve this, full-thickness wounds of size 1.767 cm2 were created at the dorsum part of nude mice and treated with keratinocytes (2 × 104 cells/cm2) and fibroblasts (3 × 104 cells/cm2) suspended in 10% PRP-enriched medium. Wound examination was conducted weekly and the animals were euthanized after 2 weeks. Gross examination showed that re-epithelialization was fastest in the PRP+cells group at both day 7 and 14, followed by the PRP group and NT group receiving no treatment. Only the PRP+cells group achieved complete wound closure by 2 weeks. Epidermal layer was presence in the central region of the wound of the PRP+cells and PRP groups but absence in the NT group. Comparison between the PRP+cells and PRP groups showed that the PRP+cells-treated wound was more mature as indicated by the presence of thinner epidermis with single cell layer thick basal keratinocytes and less cellular dermis. In summary, the combination of low cell density and diluted PRP creates a synergistic effect which expedites the healing of full-thickness wounds. This combination has the potential to be developed as a rapid wound therapy via the direct application of freshly harvested skin cells in diluted PRP.

The mouse dorsal skin fold chamber as a means for the analysis of tissue engineered skin.

The therapy of extensive and deep burn wounds is still a challenging task for reconstructive plastic surgery. The outcome is generally not satisfactory, neither from the functional nor from the aesthetic aspect. Several available skin substitutes are used but there is need for optimization of new skin substitutes which have to be tested in vitro as well as in vivo. Here, we show that the dorsal skin fold chamber preparation of mice is well suited for the testing of skin substitutes in vivo. Dermal skin constructs consisting of matriderm(®) covered with a collagen type I gel were inserted into full thickness skin wounds in the skin fold chambers. The skin substitutes integrated well into the adjacent skin and got epithelialized from the wound edges within 11 days. The epithelialization by keratinocytes is the prerequisite that also cell-free dermal substitutes might be used in the case of the lack of sufficient areas to gain split thickness skin grafts. Further advantage of the chambers is the lack of wound contraction, which is common but undesired in rodent wound healing. Furthermore, this model allows a sophisticated histological as well as immunohistochemical analysis. As such, we conclude that this model is well suited for the analysis of tissue engineered skin constructs. Besides epithelialization the mode and extend of neovascularization and contraction of artificial grafts may be studied under standardized conditions.

A review of tissue-engineered skin bioconstructs available for skin reconstruction.

Situations where normal autografts cannot be used to replace damaged skin often lead to a greater risk of mortality, prolonged hospital stay and increased expenditure for the National Health Service. There is a substantial need for tissue-engineered skin bioconstructs and research is active in this field. Significant progress has been made over the years in the development and clinical use of bioengineered components of the various skin layers. Off-the-shelf availability of such constructs, or production of sufficient quantities of biological materials to aid rapid wound closure, are often the only means to help patients with major skin loss. The aim of this review is to describe those materials already commercially available for clinical use as well as to give a short insight to those under development. It seeks to provide skin scientists/tissue engineers with the information required to not only develop in vitro models of skin, but to move closer to achieving the ultimate goal of an off-the-shelf, complete full-thickness skin replacement.

Clinical experiences of using a cellulose dressing on burns and donor site wounds.

These preliminary results suggest this temporary skin substitute reduces pain and achieves comparable healing rates to other dressings. Furthermore, its transparency enables regular inspection of the wound bed for signs of infection.

Markers to evaluate the quality and self-renewing potential of engineered human skin substitutes in vitro and after transplantation.

We screened a series of antibodies for their exclusive binding to the human hair follicle bulge. In a second step these antibodies were to be used to identify basal keratinocytes and potential epithelial stem cells in the human epidermis and in engineered skin substitutes. Of all the antibodies screened, we identified only one, designated C8/144B, that exclusively recognized the hair follicle bulge. However, C8/144B-binding cells were never detected in the human epidermal stratum basale. In the bulge C8/144B-binding cells gave rise to cytokeratin 19-positive cells, which were also tracked in the outer root sheath between bulge and the hair follicle matrix. Remarkably, cytokeratin 19-expressing cells were never detected in the hair follicle infundibulum. Yet, cytokeratin 19-expressing keratinocytes were found in the epidermal stratum basale of normal skin as a subpopulation of cytokeratin 15-positive (not C8/144B-positive) basal keratinocytes. Cytokeratin 19/cytokeratin 15-positive keratinocytes decreased significantly with age. We suggest that cytokeratin 19-expressing cells represent a subpopulation of basal keratinocytes in neonates and young children (up to 1.5 years) that is particularly adapted to the lateral expansion of growing skin. Our data show that cytokeratin 19 in combination with cytokeratin 15 is an important marker to routinely monitor epidermal homeostasis and (at least indirectly) the self-renewing potential of engineered skin.

Influence of bioengineered skin substitutes on diabetic foot ulcer and venous leg ulcer outcomes.

This systematic review indicates that bioengineered skin substitutes with a dermal component may improve healing outcomes in diabetic foot ulcers and venous leg ulcers. However, better designed trials with longer follow-up periods are needed.

[Skin replacement with biological and biosynthetic materials following burn injury]. / Bôrpótlási lehetôségek biológiai és bioszintetikus anyagokkal kiterjedt égési sérülésben.

Autotransplantation is currently regarded as the optimal skin replacement method, sufficient donor site, however, is often not available in extensively burned patients. Intensive research and development of skin replacement products is conducted worldwide in order to decrease the size of the required donor site. Short- and long-term wound coverage is made possible by temporary synthetic and non-synthetic skin substitutes. Autografts and cultured epithelial autografts are used for permanent skin substitution. Until this is possible, the barrier function of the skin is provided by bio-engineered temporary skin substitutes. Some products and methods are currently available in Hungary, while others are still in the introductory phase. In order to provide an overview, authors summarize the skin replacement methods and compare the different skin replacement products used worldwide from the perspective of the burn surgeon. The use of new methods to be introduced in the near future needs to be rationalized due to financial considerations.

Current issues regarding skin substitutes using living cells as industrial materials.

There have been many clinical cases of skin treatment using cultured epidermis, as established by H. Green in 1975. This procedure, famously, made it possible to make artificial skin using living cells. Permanent coverage for injury wounds was achieved with cultured epidermis made from autologous cells. Recently, many types of skin substitutes using living cells have been used clinically. The extent to which cellular skin substitute techniques established through basic research can be incorporated into general medical treatment is a controversial issue at present. Some techniques are at the commercializing stage as medical materials. Cultured epidermis, as described above, cultured dermis, and skin equivalent are already well established. In this article, we will describe the current issues regarding skin substitutes using living cells.

The role of fibroblasts in tissue engineering and regeneration.

Fibroblasts are mesenchymal cells that can be readily cultured in the laboratory and play a significant role in epithelial-mesenchymal interactions, secreting various growth factors and cytokines that have a direct effect on epidermal proliferation, differentiation and formation of extracellular matrix. They have been incorporated into various tissue-engineered products such as Dermagraft (Advanced BioHealing, La Jolla, CA, U.S.A.) and Apligraf (Novartis, Basel, Switzerland) and used for a variety of clinical applications, including the treatment of burns, chronic venous ulcers and several other clinical applications in dermatology and plastic surgery. In this article we review the cell biology of dermal fibroblasts and discuss past and current experience of the clinical use of cultured fibroblasts.

Differential expression of matrix metalloproteinase-1 in vitro corresponds to tissue morphogenesis and quality assurance of cultured skin substitutes.

OBJECTIVE: To determine if matrix metalloproteinase-1 (MMP-1) was involved in the premature degradation of the dermal component in cultured skin substitutes (CSS) prepared with cells from burn patients. METHODS AND RESULTS: CSS 645 and 647 were prepared from clinical human fibroblasts (HF) and keratinocytes (HK) that demonstrated premature degradation of collagen-glycosaminoglycan sponges in vitro. The control CSS were prepared from clinical HF and HK, CSS 648, and a pre-clinical cell strain, CSS 644 that did not degrade the sponges. Surface electrical capacitance measures surface hydration and was significantly higher for CSS 647 from days 9 through 14. MTT (3-[4,5-dimethylthiazol-2-yl]- diphenyltetrazolium bromide) conversion, an indicator of cellular viability was significantly lower for the 6-mm punch biopsies from CSS 645 and 647 at day 15 as compared to control CSS. MMP-1 protein levels measured by ELISA were significantly higher in medium from HF 645 and 647 than controls on the day of CSS inoculation. At day 14 of incubation, the mean MMP-1 concentration was significantly elevated in the medium from CSS 645 and 647 versus the controls, CSS 644 and 648. Western blots, and casein zymography demonstrated the presence of the latent and active forms of MMP-1 in the HF and CSS media, respectively. CONCLUSION: MMP-1 was significantly higher in the media from two of the four HF strains and CSS after a 24 h incubation period. Elevated MMP-1 coincided with premature degradation of the dermal substitute in vitro, and reduced numbers of CSS that met quality assurance standards for clinical transplantation.

Regulatory and microbiological safety issues surrounding cell and tissue-engineering products.

Cell therapies and tissue-engineered products that contain living cells are potentially some of the most exciting of the novel therapeutic products currently under development. These products, however, present a number of important safety issues, particularly with respect to the transmission of human viruses. In addition, the short shelf life of these products precludes the normally extensive characterization performed on other biotherapeutic products. Careful examination of the risks and extensive testing of the raw materials have been used in place of product testing to ensure safety.

The efficacy and safety of Dermagraft in improving the healing of chronic diabetic foot ulcers: results of a prospective randomized trial.

OBJECTIVE: To determine if a human fibroblast-derived dermal substitute could promote the healing of diabetic foot ulcers. RESEARCH DESIGN AND METHODS: A randomized, controlled, multicenter study was undertaken at 35 centers throughout the U.S. and enrolled 314 patients to evaluate complete wound closure by 12 weeks. Patients were randomized to either the Dermagraft treatment group or control (conventional therapy). Except for the application of Dermagraft, treatment of study ulcers was identical for patients in both groups. All patients received pressure-reducing footwear and were allowed to be ambulatory during the study. RESULTS: The results demonstrated that patients with chronic diabetic foot ulcers of >6 weeks duration experienced a significant clinical benefit when treated with Dermagraft versus patients treated with conventional therapy alone. With regard to complete wound closure by week 12, 30.0% (39 of 130) of Dermagraft patients healed compared with 18.3% (21 of 115) of control patients (P = 0.023). The overall incidence of adverse events was similar for both the Dermagraft and control groups, but the Dermagraft group experienced significantly fewer ulcer-related adverse events. CONCLUSIONS: The data from this study show that Dermagraft is a safe and effective treatment for chronic diabetic foot ulcers.