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Slough is a well‐known feature of non‐healing wounds. This pilot study aims to determine the proteomic and microbiologic components of slough as well as interrogate the associations between wound slough components and wound healing. Ten subjects with slow‐to‐heal wounds and visible slough were enrolled. Aetiologies included venous stasis ulcers, post‐surgical site infections and pressure ulcers. Patient co‐morbidities and wound healing outcome at 3‐months post‐sample collection was recorded. Debrided slough was analysed microscopically, through untargeted proteomics, and high‐throughput bacterial 16S‐ribosomal gene sequencing. Microscopic imaging revealed wound slough to be amorphous in structure and highly variable. 16S‐profiling found slough microbial communities to associate with wound aetiology and location on the body. Across all subjects, slough largely consisted of proteins involved in skin structure and formation, blood‐clot formation and immune processes. To predict variables associated with wound healing, protein, microbial and clinical datasets were integrated into a supervised discriminant analysis. This analysis revealed that healing wounds were enriched for proteins involved in skin barrier development and negative regulation of immune responses. While wounds that deteriorated over time started off with a higher baseline Bates‐Jensen Wound Assessment Score and were enriched for anaerobic bacterial taxa and chronic inflammatory proteins. To our knowledge, this is the first study to integrate clinical, microbiome, and proteomic data to systematically characterise wound slough and integrate it into a single assessment to predict wound healing outcome. Collectively, our findings underscore how slough components can help identify wounds at risk of continued impaired healing and serves as an underutilised biomarker. [ABSTRACT FROM AUTHOR]

Key points: Several distinct strategies produce and conserve heat to maintain the body temperature of mammals, each associated with unique physiologies, with consequences for wellness and disease susceptibilityHighly regulated properties of skin offset the total requirement for heat production We hypothesize that the adipose component of skin is primarily responsible for modulating heat flux; here we evaluate the relative regulation of adipose depots in mouse and human, to test their recruitment to heat production and conservationWe found that insulating mouse dermal white adipose tissue accumulates in response to environmentally and genetically induced cool stress; this layer is one of two adipose depots closely apposed to mouse skin, where the subcutaneous mammary gland fat pads are actively recruited to heat productionIn contrast, the body‐wide adipose depot associated with human skin produces heat directly, potentially creating an alternative to the centrally regulated brown adipose tissue Mammalian skin impacts metabolic efficiency system‐wide, controlling the rate of heat loss and consequent heat production. Here we compare the unique fat depots associated with mouse and human skin, to determine whether they have corresponding functions and regulation. For humans, we assay a skin‐associated fat (SAF) body‐wide depot to distinguish it from the subcutaneous fat pads characteristic of the abdomen and upper limbs. We show that the thickness of SAF is not related to general adiposity; it is much thicker (1.6‐fold) in women than men, and highly subject‐specific. We used molecular and cellular assays of β‐adrenergic‐induced lipolysis and found that dermal white adipose tissue (dWAT) in mice is resistant to lipolysis; in contrast, the body‐wide human SAF depot becomes lipolytic, generating heat in response to β‐adrenergic stimulation. In mice challenged to make more heat to maintain body temperature (either environmentally or genetically), there is a compensatory increase in thickness of dWAT: a corresponding β‐adrenergic stimulation of human skin adipose (in vivo or in explant) depletes adipocyte lipid content. We summarize the regulation of skin‐associated adipocytes by age, sex and adiposity, for both species. We conclude that the body‐wide dWAT depot of mice shows unique regulation that enables it to be deployed for heat preservation; combined with the actively lipolytic subcutaneous mammary fat pads they enable thermal defence. The adipose tissue that covers human subjects produces heat directly, providing an alternative to the brown adipose tissues. [ABSTRACT FROM AUTHOR]

Deep partial thickness burns are clinically prevalent and difficult to diagnose. In order to develop methods to assess burn depth and therapies to treat deep partial thickness burns, reliable, accurate animal models are needed. The variety of animal models in the literature and the lack of precise details reported for the experimental procedures make comparison of research between investigators challenging and ultimately affect translation to patients. They sought to compare deep partial thickness porcine burn models from five well-established laboratories. In doing so, they uncovered a lack of consistency in approaches to the evaluation of burn injury depth that was present within and among various models. They then used an iterative process to develop a scoring rubric with an educational component to facilitate burn injury depth evaluation that improved reliability of the scoring. Using the developed rubric to re-score the five burn models, they found that all models created a deep partial thickness injury and that agreement about specific characteristics identified on histological staining was improved. Finally, they present consensus statements on the evaluation and interpretation of the microanatomy of deep partial thickness burns in pigs. [ABSTRACT FROM AUTHOR]

Background: A phase 3b, open-label, multicenter, expanded-access study (NCT04123548) evaluated safety and clinical outcomes of StrataGraft treatment in adults with deep partial-thickness thermal burns with intact dermal elements., Methods: Adult patients with 3 % to < 50 % total body surface area burns were treated with a single application of ≤ 1:1 meshed StrataGraft and followed for 24 weeks. Primary endpoint was count and percentage of patients with treatment-emergent adverse events (TEAEs). Secondary endpoints included confirmed wound closure (WC) at Week 12, durable WC at Week 24, time to WC, scar evaluation, and wound infection-related events., Results: Fifty-two patients with 96 treatment sites were enrolled. Pruritus was the most common TEAE (22 patients [42.3 %]). Twenty serious TEAEs occurred in 10 patients (19.2 %); none were related to StrataGraft. There were 4 (7.7 %) deaths (aspiration, myocardial infarction, self-injury, Gram-negative rod sepsis); none were related to StrataGraft. Confirmed WC was achieved by Week 12 in 33 patients (63.5 %; 95 % CI: 50.4-76.5 %) and 69 treatment sites (71.9 %; 95 % CI: 62.9-80.9 %). Durable WC was achieved by Week 24 in 29 patients (55.8 %; 95 % CI: 42.3-69.3 %) and 58 treatment sites (60.4 %; 95 % CI: 50.6-70.2 %)., Conclusions: StrataGraft demonstrated clinical benefit. Safety data were consistent with previously reported findings., Competing Interests: Declaration of Competing Interest James H. Holmes IV: Equity positions in Abbott Labs, AbbVie, Change Healthcare Inc, and Imbed Biosciences. Consultant for Avita Medical and has received research support from Avita Medical, Mallinckrodt Pharmaceuticals/Stratatech, SpectralMD, and Keranetics. Jeffrey W. Shupp: Research funding from Mallinckrodt Pharmaceuticals, Avita Medical, Urgo Medical, ACell, and Kerecis. JWS has been a consultant for Integra LifeSciences and Avita Medical. Tracee Short: Participated in the clinical advisory boards for Avita Medical, Mallinckrodt Pharmaceuticals, Synergy Biologics, Polynovo, and KCI. Victor C. Joe: Participated in a Mallinckrodt Pharmaceuticals Advisory Board relating to StrataGraft. Jeffrey Litt: Participated in the speaker bureau for Acelity/3AM (ended) and advisory board for Vericel (ended). Joshua Carson: Received research funding from Mallinckrodt Pharmaceuticals and the Biomedical Research and Development Authority (BARDA) and personal fees from Integra LifeSciences, Avita Medical, and Mallinckrodt Pharmaceuticals. Jeffrey E. Carter: Equity positions in PermeaDerm, Inc and is a consultant for Avita Medical. Research support from Avita Medical, SpectralMD, and Keranetics. Lucy Wibbenmeyer: Received research funding from Mallinckrodt Pharmaceuticals, Mediwound, and Biomedical Research and Development Authority (BARDA) and consultant fees from Vericel, Allosource, and Mallinckrodt Pharmaceuticals. Helen Hahn: Previous employee of Mallinckrodt Pharmaceuticals. Janice M. Smiell: Previous employee of Mallinckrodt Pharmaceuticals. Randi Rutan: Previous employee of Mallinckrodt Pharmaceuticals. Richard Wu: Employee of Mallinckrodt Pharmaceuticals. Angela L. F. Gibson: Received grant/research support from Mallinckrodt Pharmaceuticals., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Competing Interests: The authors report no conflicts of interest.

Neutrophils accumulate early in tissue injury. However, the cellular and functional heterogeneity of neutrophils during homeostasis and in response to tissue damage remains unclear. In this study, we use larval zebrafish to understand neutrophil responses to thermal injury. Single-cell transcriptional mapping of myeloid cells during a 3-d time course in burn and control larvae revealed distinct neutrophil subsets and their cell-cell interactions with macrophages across time and conditions. The trajectory formed by three zebrafish neutrophil subsets resembles human neutrophil maturation, with varying transition patterns between conditions. Through ligand-receptor cell-cell interaction analysis, we found that neutrophils communicate more in burns in a pathway and temporal manner. Finally, we identified the correlation between zebrafish myeloid signatures and human burn severity, establishing GPR84+ neutrophils as a potential marker of early innate immune response in burns. This work builds a comparative single-cell transcriptomic framework to identify neutrophil markers of tissue damage using model organisms., (Copyright © 2024 by The American Association of Immunologists, Inc.)

The skin and its microbiome function to protect the host from pathogen colonization and environmental stressors. In this study, using the Wisconsin Miniature Swine™ model, we characterize the porcine skin fungal and bacterial microbiomes, identify bacterial isolates displaying antifungal activity, and use whole-genome sequencing to identify biosynthetic gene clusters encoding for secondary metabolites that may be responsible for the antagonistic effects on fungi. Through this comprehensive approach of paired microbiome sequencing with culturomics, we report the discovery of novel species of Corynebacterium and Rothia. Further, this study represents the first comprehensive evaluation of the porcine skin mycobiome and the evaluation of bacterial-fungal interactions on this surface. Several diverse bacterial isolates exhibit potent antifungal properties against opportunistic fungal pathogens in vitro. Genomic analysis of inhibitory species revealed a diverse repertoire of uncharacterized biosynthetic gene clusters suggesting a reservoir of novel chemical and biological diversity. Collectively, the porcine skin microbiome represents a potential unique source of novel antifungals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: This analysis includes pooled safety data from 2 clinical trials (NCT01437852; NCT03005106) that evaluated the safety and efficacy of StrataGraft in patients with deep partial-thickness (DPT) burns., Methods: The study enrolled 101 adult patients with thermal burns covering 3-49% of total body surface area. Patients were followed for up to 1 year. The pooled safety events included: adverse events (AEs), adverse reactions (ARs), serious AEs (SAEs), discontinuation, and deaths; immunological responses (reactivity to panel reactive antibodies [PRA] and human leukocyte antigen [HLA] class 1 alleles); and persistence of allogeneic DNA from StrataGraft., Results: Eighty-seven (86.1%) patients experienced 397 AEs. Thirty patients (29.7%) experienced ARs; 16 patients (15.8%) experienced SAEs. The most frequent AEs were pruritus (n = 31; 30.7%), and blister, hypertension, and hypertrophic scar (n = 11 each; 10.9%); the most common AR was pruritus (n = 13; 12.9%). One patient discontinued the study; 2 patients experienced SAEs (unrelated to StrataGraft) leading to death. PRA and HLA allele reactivity was ≤ 25% at Month 3, with no persistent allogeneic DNA from StrataGraft., Conclusions: StrataGraft was well tolerated by patients, with a safety profile similar to autograft. StrataGraft may offer a safe alternative to autograft for DPT burns., Competing Interests: Conflicts of interest JHH has equity ownership in Abbott Labs, AbbVie, Imbed Biosciences, and Change Healthcare. JHH is a consultant to Avita Medical and Stratatech and Mallinckrodt Pharmaceuticals plc, Hampton, NJ. LCC, LDF, and BTK have nothing to disclose. JEC has equity positions in PermeaDerm, Inc, and is a consultant for Avita Medical. Research support from Avita Medical, SpectralMD, and Keranetics. KF has been involved in clinical studies for the American Burn Association, Atox-Bio, BARDA, Baxter, Polynovo Biomaterials, Mallinckrodt Pharmaceuticals, Integra LifeSciences, MediWound, MiMedx, Skingenix, Propanolol, Avita Medical, The Canadian Institutes of Health, and Stratatech, all outside the submitted work. HDH, RR, JMS, and RW are employees and shareholders of Mallinckrodt Pharmaceuticals. ALFG is a consultant to Mallinckrodt Pharmaceuticals and Stratatech, a Mallinckrodt company., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: This phase 3 study evaluated StrataGraft construct as a donor-site sparing alternative to autograft in patients with deep partial-thickness (DPT) burns., Methods: Patients aged ≥18 years with 3-49% total body surface area (TBSA) thermal burns were enrolled. In each patient, 2 DPT areas (≤2000cm 2 total) of comparable depth after excision were randomized to either cryopreserved StrataGraft or autograft. Coprimary endpoints were: the difference in percent area of StrataGraft treatment site and autograft treatment site autografted at Month 3 (M3), and the proportion of patients achieving durable wound closure of the StrataGraft site without autograft at M3. Safety assessments were performed in all patients. Efficacy and safety follow-up continued to 1 year., Results: Seventy-one patients were enrolled. By M3, there was a 96% reduction in mean percent area of StrataGraft treatment sites that required autografting, compared with autograft treatment sites (4.3% vs 102.1%, respectively; P<.0001). StrataGraft treatment resulted in durable wound closure at M3 without autografting in 92% (95% CI: 85.6, 98.8; n/n 59/64) of patients for whom data were available. The most common StrataGraft-related adverse event was pruritus (15%)., Conclusions: Both coprimary endpoints were achieved. StrataGraft may offer a new treatment for DPT burns to reduce the need for autografting., Clinical Trial Identifier: NCT03005106., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Early mechanisms underlying the progressive tissue death and the regenerative capability of burn wounds are understudied in human skin. A clinically relevant, reproducible model for human burn wound healing is needed to elucidate the early changes in the human burn wound environment. This study reports a reproducible contact burn model on human skin that explores the extent of tissue injury and healing over time, and defines the inter-individual variability in human skin to enable use in mechanistic studies on burn wound progression and healing., Methods: Using a customized burn device, contact burns of various depths were created on human skin by two operators and were evaluated for histologic depth by three raters to determine reproducibility. Early burn wound progression and wound healing were also evaluated histologically after the thermally injured human skin was cultured ex vivo for up to 14 days., Results: Burn depths were reproducibly generated on human skin in a temperature- or time-dependent manner. No significant difference in operator-created or rater-determined depth was observed within each patient sample. However, significant inter-individual variation was identified in burn depth in ten patient samples. Burn-injured ex vivo human skin placed into culture demonstrated differential progression of cell death and collagen denaturation for high and low temperature contact burns, while re-epithelialization was observed in superficial burn wounds over a period of 14 days., Conclusion: This model represents an invaluable tool to evaluate the inter-individual variability in early burn wound progression and wound healing to complement current animal models and enhance the translation of preclinical research to improvements in patient care., (Copyright © 2020 Elsevier Ltd and ISBI. All rights reserved.)

In the management of indeterminate-depth burns (IDB), common challenges include the ability to predict time to healing and regenerative potential, risk of burn wound progression, and timing of excision. Several technologies exist to aid in determination of the depth of a burn injury, yet surgeons continue to rely on the naked eye-visual assessment-as the standard of care. Newer and improved imaging technologies are closing in on the goal of inexpensive, accurate, noninvasive modalities for depth determination. Likewise, management of IDB is becoming more sophisticated as newer wound healing technologies continue to be developed. By describing what is meant by "indeterminate" depth burns, and their associated challenges, we hope to stimulate interest in research to develop new therapies and management strategies. The ultimate goal is to treat IDB without the need for autografts., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: This open-label, controlled, randomized study assessed the safety, tolerability, and efficacy of StrataGraft tissue compared to autograft in the treatment of deep partial-thickness (DPT) burns., Methods: Thirty subjects with DPT thermal burns (3%-43% total body surface area) were treated with StrataGraft tissue as follows: cohort 1, ≤220 cm 2 refrigerated tissue; cohort 2, ≤440 cm 2 refrigerated tissue; and cohort 3, ≤440 cm 2 cryopreserved tissue. On each subject, two comparable areas of DPT burn were randomized to receive StrataGraft tissue or autograft. Coprimary end points were the percent area of the StrataGraft tissue treatment site undergoing salvage autografting by Day 28 and wound closure of treatment sites by 3 months., Results: By Day 28, no StrataGraft tissue treatment sites underwent autografting. By 3 months, 93% and 100% of the StrataGraft tissue and autograft treatment sites achieved complete wound closure, respectively. No significant differences in observer total and overall opinion POSAS scores between StrataGraft tissue and autograft treatment sites were observed at any timepoint. The most common adverse event was pruritus (17%)., Conclusions: StrataGraft tissue treatment of DPT thermal burns reduced the need for autograft, resulted in wound closure and treatment-site cosmesis comparable to that of autograft, and was well tolerated., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The regenerative capacity of burn wounds, and the need for surgical intervention, depends on wound depth. Clinical visual assessment is considered the gold standard for burn depth assessment but it remains a subjective and inaccurate method for tissue evaluation. The purpose of this study was to compare visual assessment with microscopic and molecular techniques for human burn depth determination, and illustrate differences in the evaluation of tissue for potential regenerative capacity. Using intraoperative visual assessment, patients were identified as having deep partial thickness or full thickness burn wounds. Tangential excisions of burn tissue were processed with hematoxylin and eosin to visualize tissue morphology, lactate dehydrogenase assay to ascertain cellular viability, and Keratin-15 and Ki67 to identify epidermal progenitor cells and proliferative capacity, respectively. RNA from deep partial and full thickness burn tissue as well as normal tissue controls were submitted for RNA sequencing. Lactate dehydrogenase, Keratin-15, and Ki67 were found throughout the excised burn wound tissue in both deep partial thickness burn tissues and in the second tangential excision of full thickness burn tissues. RNA sequencing demonstrated regenerative capacity in both deep partial and full thickness burn tissue, however a greater capacity for regeneration was present in deep partial thickness compared with full thickness burn tissues. In this study, we highlight the discordance that exists between the intraoperative clinical identification of burn injury depth, and microscopic and molecular determination of viability and regenerative capacity. Current methods utilizing visual assessment for depth of injury are imprecise, and can lead to removal of viable tissue. Additionally, hematoxylin and eosin microscopic analysis should not be used as the sole method in research or clinical determination of depth, as there are no differences in staining between viable and nonviable tissue., (© 2018 by the Wound Healing Society.)

Background: Cell viability is paramount to wound healing in burn injury. Current methods to determine depth of burn injury in the research setting are based on the subjective visualization of cell viability using hematoxylin and eosin staining. The purpose of this study was to develop a simplified method of lactate dehydrogenase (LDH) staining to identify viable cells in frozen sections of human burn tissue that can be used in the research setting., Materials and Methods: After surgical excision, human burn tissue was processed for histologic evaluation. Tissues were fixed and protected with sucrose incubation before cryopreservation. An LDH staining method was developed and evaluated for prolonged stain stability. To evaluate cellular viability in the tissues as demonstrated by enzymatic activity of LDH, digital images of tissue sections were obtained immediately after and 1 mo after staining., Results: The cryopreserved sections of deep partial thickness human burn tissue revealed cellular viability throughout the tissue with the exception of the most superficial region of the tissue. Unlike the hematoxylin and eosin-stained sections, clear demarcation of cellular viability was evident in the LDH-stained sections., Conclusions: Our simplified protocol identifies, without ambiguity, the viability of the cellular elements in deep partial thickness and full thickness burn injured tissue., (Copyright © 2017 Elsevier Inc. All rights reserved.)