Full Skin Thickness Burn Research Articles

The Wound-Healing Effect of a Novel Fibroblasts-Impregnated Hydroxyethylcellulose Gel in a Rat Full-Thickness Burn Model: A Preclinical Study.

Background/Objectives: The objective of this study was to assess the efficacy of a cell-containing wound dressing based on fibroblasts in hydroxyethylcellulose (HEC) gel for the local treatment of deep partial-thickness and/or full-thickness skin burns in an animal model. Methods: The rats (male Wistar, n = 100) were subjected to a full-thickness thermal burn (16 cm2). Radical necrectomy was performed one day after the burn. Three days later, the rats were randomly assigned to one of four groups: group 1 (no treatment), group 2 (chloramphenicol and methyluracil ointment, a routine clinical treatment), group 3 (a gel without cells, mock treatment), and group 4 (a dermal fibroblast-impregnated HEC gel). The treatment lasted for five days. The wound-healing process was evaluated by planimetric, cytologic, histologic, and immunohistochemical methods. Results: The differences in the rate of wound healing and the characteristics of wound cytology were identified. In the group 4, a regenerative type of cytogram was revealed, characterized by a significantly increased number of fibroblastic cells in comparison to samples from non-treated and mock-treated animals. Biopsy samples of burn wounds from animals in the group 4l demonstrated the presence of mature granulation tissue and a large number of microvessels. The repair process was stimulated, as evidenced by the increased thickness of newly formed granulation tissue and epidermis in the wound zone, elevated cellularity, and enhanced re-epithelialization activity. The number of Ki-67-positive proliferating cells was significantly higher in group 4 than in the control groups). A small number of non-proliferating donor fibroblasts was observed in the wound area 3 days after the end of treatment. Conclusions: The cell product is an effective agent for promoting wound healing during the regenerative phase. The experiments demonstrated that a gel populated by dermal fibroblasts can stimulate reparative regeneration processes in deep partial- and full-thickness burn wounds.

Noninvasive release of tendons using MRI guided focused ultrasound: a hybrid therapy using long-pulse focused ultrasound followed by thermal ablation

Introduction Magnetic Resonance-guided Focused Ultrasound (MRgFUS) thermal ablation is an effective noninvasive ultrasonic therapy to disrupt in vivo porcine tendon but is prone to inducing skin burns. We evaluated the safety profile of a novel hybrid protocol that minimizes thermal spread by combining long-pulse focused ultrasound followed by thermal ablation. Methods In-vivo Achilles tendons (hybrid N = 15, thermal ablation alone N = 21) from 15 to 20 kg Yorkshire pigs were randomly assigned to 6 treatment groups in two studies. The first (N = 21) was ablation (600, 900, or 1200 J). The second (N = 15) was hybrid: pulsed FUS (13.5 MPa peak negative pressure) followed by ablation (600, 900, or 1200 J). Measurements of ankle range of motion, tendon temperature, thermal dose (240 CEM43), and assessment of skin burn were performed in both groups. Results Rupture was comparable between the two protocols: 1/5 (20%), 5/5 (100%) and 5/5 (100%) for hybrid protocol, compared to 2/7 (29%), 6/7 (86%) and 7/7 (100%) for the ablation-only protocol with energies of 600, 900, and 1200 J, respectively. The hybrid protocol produced lower maximum temperatures, smaller areas of thermal dose, fewer thermal injuries to the skin, and fewer full-thickness skin burns. The standard deviation for the area of thermal injury was also smaller for the hybrid protocol, suggesting greater predictability. Conclusion This study demonstrated a hybrid MRgFUS protocol combining long-pulse FUS followed by thermal ablation to be noninferior and safer than an ablation-only protocol for extracorporeal in-vivo tendon rupture for future clinical application for noninvasive release of contracted tendon.

In Situ Biomaterial Printing Technology Based on Transfer Molding

Skin is one of the largest and most important organs in the human body. When faced with a large, full-thickness skin burn, there is not enough healthy skin to graft. In this case, we can replace our skin with biomaterials. Due to its characteristics of water permeability, antibacterial properties, biocompatibility, self-debridement, and so on, the hydrogel is undoubtedly a better alternative material. Among the methods of hydrogel preparation, in situ material molding has attracted a lot of attention for its unique advantages. Here, we proposed an in situ forming process based on transfer printing and verified the feasibility of the transfer printing process using a three-axis platform. The in situ molding equipment was designed to realize the in situ material transfer process, which prepared the conditions for the subsequent process optimization, cell experiment verification, and animal experiment.

In Vivo Study of the Effects of Propranolol, Timolol, and Minoxidil on Burn Wound Healing in Wistar Rats.

Propranolol, timolol, and minoxidil have all shown benefits in treatment of burn injury and other skin wounds. The study evaluated their effects on full-thickness thermal skin burns in a Wistar rat model. Performed on 50 female rats; two dorsal skin burns were created on each animal. On the next day, the rats were divided into 5 groups (n=10); each has received a specific treatment daily for 14 days: group I - topical vehicle (control), group II - topical silver sulfadiazine (SSD), group III - oral propranolol (5.5mg) associated with topical vehicle, group IV - topical timolol 1% cream, group V - topical minoxidil 5% cream. Wound contraction rates, malondialdehyde (MDA), glutathione (GSH, GSSG), and catalase activity in skin and/or serum were evaluated, and histopathological analyses were performed. Propranolol did not show advantages in necrosis prevention and wound contraction and healing, and did not reduce oxidative stress. It impaired keratinocyte migration, and promoted ulceration, chronic inflammation, and fibrosis, yet reducing the necrotic zone. Timolol prevented necrosis and promoted contraction and healing, increased antioxidant capacity and promoted keratinocyte migration and neo capillarization in comparison to the other treatments. Minoxidil reduced necrosis and enhanced contraction, resulting in positive outcomes after 1 week of treatment regarding local antioxidant defense, keratinocyte migration, neo capillarization, chronic inflammation, and fibrosis rates. However, after 2 weeks, it resulted in contrasting outcomes. In conclusion, topical timolol promoted wound contraction and healing, reducing local oxidative stress and improving keratinocyte migration, bringing arguments for potential benefits in skin epithelization.

Engineered multi-functional, pro-angiogenic collagen-based scaffolds loaded with endothelial cells promote large deep burn wound healing.

The lack of vascularization associated with deep burns delays the construction of wound beds, increases the risks of infection, and leads to the formation of hypertrophic scars or disfigurement. To address this challenge, we have fabricated a multi-functional pro-angiogenic molecule by grafting integrin αvβ3 ligand LXW7 and collagen-binding peptide (SILY) to a dermatan sulfate (DS) glycosaminoglycan backbone, named LXW7-DS-SILY (LDS), and further employed this to functionalize collagen-based Integra scaffolds. Using a large deep burn wound model in C57/BLK6 mice (8-10weeks old, 26-32g, n = 39), we demonstrated that LDS-modified collagen-based Integra scaffolds loaded with endothelial cells (ECs) accelerate wound healing rate, re-epithelialization, vascularization, and collagen deposition. Specifically, a 2 cm × 3cm full-thickness skin burn wound was created 48h after the burn, and then wounds were treated with four groups of different dressing scaffolds, including Integra + ECs, Integra + LDS, and Integra + LDS + ECs with Integra-only as the control. Digital photos were taken for wound healing measurement on post-treatment days 1, 7, 14, 21, 28, and 35. Post-treatment photos revealed that treatment with the Intgera + LDS + ECs scaffold exhibited a higher wound healing rate in the proliferation phase. Histology results showed significantly increased re-epithelialization, increased collagen deposition, increased thin and mixed collagen fiber content, increased angiogenesis, and shorter wound length within the Integra + LDS + ECs group at Day 35. On Day 14, the Integra + LDS + ECs group showed the same trend. The relative proportions of collagen changed from Day 14 to Day 35 in the Integra + LDS + ECs and Integra + ECs groups demonstrated decreased thick collagen fiber deposition and greater thin and mixed collagen fiber deposition. LDS-modified Integra scaffolds represent a promising novel treatment to accelerate deep burn wound healing, thereby potentially reducing the morbidity associated with open burn wounds. These scaffolds can also potentially reduce the need for autografting and morbidity in patients with already limited areas of harvestable skin.

Multicenter research of the dependence of skin graft engraftment and the concentration of blood hemoglobin, total serum protein and albumin

The Objective was to evaluate the effects of the concentration of blood hemoglobin, total serum protein and albumin on skin graft engraftment frequency.Methods and Materials. The study included 186 patients with full-thickness skin burn more than 5 % of total body surface area who were treated in five different burn departments of the Russian Federation. Depending on the readiness of the wounds, all performed surgical treatments were divided into four groups: 1) simultaneous skin graft after tangential necretomy; 2) simultaneous skin graft after radical necretomy; 3) skin graft for granulation wounds; 4) skin graft for a long time existing pathologically (hyper)granulation. Venous blood was taken from all the patients 12 hours before and 12–24 hours after skin graft. The concentration of blood hemoglobin, total serum protein and albumin was determined in the obtained samples. The evaluation of skin graft engraftment frequency was carried out by a combined method on the 7th day after skin graft. The data obtained were processed using descriptive and nonparametric statistics.Results. The concentration of total serum protein (p=0.001) and albumin (p=0.000) had a significant impact on the skin grafting results. This relationship was most pronounced during skin grafting on granulating wounds and after radical necretomy. The data obtained were identical for meshed and non-meshed skin grafts. Decrease in hemoglobin concentration did not lead to a degradation of skin grafts (p=0.068) in any of the study groups. According to the results of the laboratory parameters ranking, it was found that maintaining the concentration of total serum protein more than 6 g/dL allows 1.3 times to improve the results of skin grafting, and albumin concentrations more than 3.5 g/dL – 1.4.Conclusion. During the study, we were unable to confirm the existence of a relationship between the concentration of blood hemoglobin and the results of skin graft engraftment by any of the statistical analysis methods in any of the study groups. Accordingly, the inability to transfuse erythrocytes to a patient with anemia below 9–8 g/dL cannot be considered as an absolute contraindication for early surgical treatment of burned patients. Apparently, the concentration of total serum protein and albumin has a much greater effect on the skin grafting results. Trigger values of total serum protein can be recognized as 6 g/dL (albumin – 3.5 g/dL), which provides good results of engraftment in at least 90 % of operated patients.

Epidemiological and Clinical Characteristics of 5,569 Pediatric Burns in Central China From 2013 to 2019.

BackgroundPediatric burns of all the ages are prevalent worldwide, posing a severe health risk to children. This study aims to examine pediatric burns' clinical characteristics and epidemiology in central China.MethodsThe pediatric patients of the Burn Research Center, Department of the First People's Hospital of Zhengzhou City from 2013 to 2019 were retrospectively studied and the relevant data were collected from the hospitalized medical records [e.g., demographic, etiology, length of stay (LOS), age, gender, burn area and depth, number of surgeries, cost, and outcome].ResultsA total of 5,569 pediatric burn patients were included, accounting for 43.9% of the total burn population. Electric burns represented a relatively small proportion (1.17%) but were more likely to lead to disabilities or death than scalds (90.63%) and flames (5.12%). The median age was 2 years [interquartile range (IQR): 1–4] and the boys/girls ratio ranged from 1.3:1 to 1.6:1. The most commonly burnt anatomic sites were the limbs (38.3%), with a median %TBSA (total body surface area) of 6 (IQR: 4–10). The complications of shock and pneumonia accounted for 7.6 and 19.2%, respectively. The peak months of pediatric burns included January, May, and August and the rural/urban ratio reached 1.61:1. The percentage of burn wounds treated surgically increased considerably from 2013 to 2019 (3.8 vs. 37.8%). The median hospital LOS was 15 days (IQR: 8–28 days), with the three high-risk factors (e.g., more surgeries, more %TBSA, full-thickness skin burns). The median cost of hospitalization was 1,511 USD (IQR: 848–2,648 USD) and the main risk factors consisted of full-thickness burns, more %TBSA, longer LOS, and more surgical procedures. Among all the patients, LA50 was 78.63% (95% CI = 75.12–83.45) and the overall mortality reached 0.1% since seven deaths were recorded.ConclusionScalds, flames, contact, and chemicals are the main causes of burns among children aged 1–5 years in central China. Accordingly, various prevention strategies should be employed depending upon the cause of the burn.

Efficacy of stromal vascular fraction and enzyme-free mechanical isolation therapy in experimental full thickness burn wounds

Background Autologous cell suspensions obtained by a stromal vascular fraction (SVF) and enzyme-free mechanical isolation (EMI) are an alternative in the treatment of burn wounds. In this study, we aimed to investigate the effect of autologous cell suspensions obtained by SVF and EMI on full-thickness skin burn wounds. Methods A total of 45 male Sprague–Dawley rats were divided into three groups, SVF group, EMI group, and SVF + EMI group. The groups were also classified as the first, second, and third week of the burn to reveal the effect of the treatment on the burn in the early, middle, and late stages. For treatment, 0.2 ml SVF or 0.2 ml EMI was injected subcutaneously into the burn lesions of the subjects. Histopathological examination was performed on the burn wounds taken at the end of the experiment, and Ki67, CD44, CD73, CD90, and CK17 expressions were evaluated. Results Histological examination revealed that there was no improvement in the control samples, but the skin was multicellular, vascularization was present. Histologic scores in all groups was significantly better than control, and SVF + EMI was the best group in terms of recovery (p < 0.05). Ki67, CK17, CD44, CD73, and CD90 expressions were significantly higher in the treatment groups compared to the control (p < 0.05). Conclusion We found in our study that both applications significantly increased the healing of the burn wound. Moreover, SVF + EMI application provided more improvement than SVF or EMI alone.

ROS-Eliminating Carboxymethyl Chitosan Hydrogel to Enhance Burn Wound-Healing Efficacy.

Overexpression of reactive oxygen species (ROS) can lead to chronic inflammation, which limits skin wound healing. Therefore, it is of great significance to develop materials that can locally control the adverse reactions caused by excessive ROS. In this research, an ROS-sensitive hydrogel with strong free radical scavenging ability was prepared by introducing the thione (Tk) group into carboxymethyl chitosan (CMCTS) hydrogel. CMCTS hydrogel was cross-linked by NH2-Tk-NH2 agent and loaded curcumin (Cur), which possessed favorable nontoxicity, water absorption, mechanical property, biodegradability, drug release behavior, the M2 phenotype, and inflammatory factor regulating the capacity of macrophages. It is worth noting that Cur@CMCTS-Tk hydrogel can significantly inhibit oxidative damage of human fibroblasts in the H2O2-induced microenvironment and protect their viability by reducing the production of intracellular ROS. In vivo, ROS-removing hydrogel effectively accelerated the process of wound healing and possessed good regenerative properties, including hair follicle formation, promotion of new blood vessel formation, and highly orderly arrangement of collagen fibers in the full-thickness skin burn defect rat model. Hence, we expect that the Cur@CMCTS-Tk hydrogel could be used for wound treatment and tissue regeneration due to the ability to scavenge excess ROS.

793 The Giant Hogweed as A Rare Cause of Chemical Burns: A Case Series

Abstract Introduction The Giant Hogweed (Heracleum mantegazzianum) is a rare cause for chemical burns in humans and animals and is acquiring growing recognition in mainstream media as a relevant public health concern. Injuries attributed to this plant range from innocuous superficial irritation to full-thickness chemical burns. A vast majority of cases will resolve with conservative measures and effective first aid, but these case series demonstrate the clinical course of more severe injuries. Description We present a case series of 2 patients requiring admission to the Royal Group Hospitals for management of mixed thickness hogweed burns. Injuries were sustained by two separate infestations of giant hogweed in the Western Trust Area. Both patients responded to observation and conservative measures, namely effective analgesia, UV light protection, topical hydrocortisone, and dressings. Discussion Cutaneous burns induced by giant hogweed are caused by contact with its photoactive sap containing plant furocoumarins. On exposure to sunlight, the sap initiates a damaging process known as phytophotodermatitis (PPD). This process can be managed effectively with topical steroids; however, prolonged contact and subsequent sun exposure may lead to more severe skin damage. In extremely rare instances, damage may progress to full-thickness skin burns warranting operative intervention.

Effect of Silver Nanoparticles on Healing of Third-Degree Burns Infected with Pseudomonas Aeruginosa in Laboratory Mice

Abstract The treatment of full-thickness skin burn using nanomaterials is promising as a medical application reducing the risk of infection and severe dermal scarring. Therefore, this study aims to evaluate the effectiveness of nanomaterials, particularly 3% silver nanoparticles containing ointment (3% SNO), on the full-thickness skin burn of laboratory mice. A total number of 36 male mice were used, equally divided into three groups: negative control (not burned and not treated); positive control (+ve) (burned and treated with castor oil and white petroleum jelly); and SNO-treated group (burned and treated with 3% SNO). The skin of the animals’ back was shaved. A 2x0.5 cm metal plate was heated on a burner to burn the skin of the animals of positive control and SNO-treated groups. Pseudomonas aeruginosa bacterial suspension was applied to the burnt area. The application of SNO, as well as the mixture of white petroleum jelly and castor oil, was started after 6 hours of inducing burns and continued for 14 days (three times daily) in the respected groups. The SNO-treated group showed accelerated healing within 14 days demonstrated by re-epithelialization of the epidermal layer and proliferation of the fibroblasts in the dermal layer. Less healing evidence was observed in the +ve control group in the same period. In conclusion, to our knowledge, this is the first study that uses a 3% SNO formula and has found that it has a promising impact on the treatment of infected skin burns.

Endoscopic Thyroid Lobectomy: Our Early Experience at Lahore General Hospital, Lahore, Pakistan

Background Conventional Thyroid Lobectomy leaves an unpleasant neck scar. Endoscopic thyroidectomy was first applied by Huschner in 1997. Amongst the best endoscopic techniques is the one we use, referred to as the endoscopic axillary-breast-shoulder approach (ABSA) innovated by Dr. Trans Ngoc Luong. Objective To examine the safety, feasibility and cosmetic outcome of endoscopic thyroid lobectomy. Patients and Methods We performed endoscopic lobectomy in 20 patients at Lahore General Hospital (LGH) from 9th September 2016 to 31st Dec 2019. We adopted axillary-breast-shoulder approach. Inclusion criteria were age 18-45 years, solitary nodule less than 5 cm and benign FNAC. Exclusion criteria were multiple nodules, solitary nodule more than 5 cm, age more than 45years, malignant FNAC, recurrent goiter and co-morbid like DM, HTN, IHD, COPD. The parameters studied were the conversion rate, operative time, hospital stay, complications, cosmetic outcome and patient satisfaction. The results were analyzed to draw rational conclusion. Results Successful endoscopic lobectomy was performed in almost all cases with conversion to open in two cases. The median operative time was 100 minutes. No preoperative injury was inflicted. One case sustained minor skin burns which healed without any residual scar. One patient developed full thickness skin burn and one patient had seroma. All patients were discharged on first postoperative day. Excellent cosmetic outcome achieved in all patients leading to their optimum satisfaction. Conclusion Endoscopic thyroid lobectomy is a safe and feasible procedure with satisfactory cosmetic outcome for benign solitary thyroid nodules in selected patients.

Effect of PDGF-B Gene-Activated Acellular Matrix and Mesenchymal Stem Cell Transplantation on Full Thickness Skin Burn Wound in Rat Model.

Full thickness burn wounds are lack of angiogenesis, cell migration, epithelialisation and finally scar tissue formation. Tissue engineered composite graft can provide sustained release of growth factor and promote the wound healing by cell migration, early angiogenesis and proliferation of extracellular matrix and wound remodeling. The objective of this study was to evaluate the gene embedded (pDNA-platelet-derived growth factor, PDGF-B) porcine acellular urinary bladder matrix with transfected mesenchymal stem cells (rBMSC) on healing of full thickness burn wound in rat model. Full thickness burn wound of 2 × 2cm size was created in dorsum of rat model under general anesthesia. Burn wounds were treated with silver sulfadiazine; porcine acellular urinary bladder matrix (PAUBM); PAUBM transfected with pDNA-PDGF-B; PAUBM seeded with rBMSC; PAUBM seeded with rBMSC transfected with pDNA-PDGF-B in groups A, B, C, D and E respectively. The wound healing was assessed based on clinical, macroscopically, immunologically, histopathological and RT-qPCR parameters. Wound was significantly healed in group E and group D with early extracellular matrix deposition, enhanced granulation tissue formation and early angiogenesis compared to all other groups. The immunologic response against porcine acellular matrix showed that PDGF-B gene activated matrix along with stem cell group showed less antibody titer against acellular matrix than other groups in all intervals. PDGF gene activated matrix releasing the PDGF-B and promote the healing of full thickness burn wound with neovascularization and neo tissue formation. PDGF gene also enhances secretion of other growth factors results in PDGF mediated regenerative activities. This was confirmed in RT-qPCR at various time intervals. Gene activated matrix encoded for PDGF-B protein transfected stem cells have been clinically proven for early acceleration of angiogenesis and tissue regeneration in burn wounds in rat models. Evaluation of PDGF-B gene-activated acellular matrix and mesenchymal stem cell in full thickness skin burn wound in rat.

Healing potential of chitosan and decellularized intestinal matrix with mesenchymal stem cells and growth factor in burn wound in rat

Abstract Background Burns are one of the most common and devastating forms of trauma. Patients with serious thermal injury require immediate specialized care in order to minimize morbidity and mortality. The objective of this study was to evaluate the healing potential of porcine decellularized small intestinal submucosa (SIS) matrix and chitosan with mesenchymal stem cells (rMSC) and epidermal growth factor (mEGF) on the healing of full thickness burn wound in rat model. Methods One 2 × 2 cm2 size full thickness burn wound was created on the dorsum of each animal under general anaesthesia. Burn wounds were treated with silver sulfadiazine; medical grade chitosan; chitosan with rMSC; chitosan with rMSC and mEGF; decellularized porcine SIS; rMSC seeded with SIS; rMSC seeded with SIS and mEGF in groups A, B, C, D, E, F and G, respectively. Healing was evaluated on the basis of percentage of wound contraction, colour digital imaging, immunological, histopathological, immunohistochemistry and gelatin zymography observations. Results A decrease in wound area was noticed in stem cell and m-EGF treated groups. Early angiogenesis and epithelialisation was observed in groups, where decellularized SIS matrix was combined with r-MSC and m-EGF. Type III collagen was found more in control group by immunohistochemistry which indicated abnormal collagen deposition. Gelatin zymography revealed expression of MMPs in the control group suggesting a chronic nature of wound. Chitosan in combination of rMSC and mEGF proved to be efficient for full-thickness burn wound healing. Conclusion Decellularized SIS matrix when combined with r-MSC and m-EGF has healing potential and showed best healing response than conventional treatment for the reconstruction of full-thickness skin burn wounds in rats.

Influence of fibrin matrices and their released factors on epidermal substitute phenotype and engraftment.

Cultured epithelial autografts (CEAs) represent a life-saving surgical technique for full-thickness skin burns covering more than 60% total body surface area. However, CEAs present numerous drawbacks leading to heavy cosmetic and functional sequelae. In our previous study, we showed that human plasma-based fibrin matrices (hPBM) could improve the reparative potential of CEAs. Therefore, in the present work, we sought to investigate the role of hPBM compared with fibrin from purified fibrinogen (FPF) or plastic support on epidermal substitute formation and engraftment. The use of hPBM for epidermal substitute culture improved keratinocyte migration, proliferation, and epidermal substitute organization to a better extent than FPF in vitro. Both fibrin matrices favored greater dermal-epidermal junction protein deposition and prevented their degradation. Keratinocyte differentiation was also decreased using both fibrin matrices. Basement membrane protein deposition was mainly influenced by matrix whereas growth factors released from fibrin especially by hPBM were shown to enhance in vitro keratinocyte migration, proliferation, and epidermal substitute organization. Ultimately, epidermal substitutes grown on hPBM displayed better engraftment rates than those cultured on FPF or on plastic support in a NOD-SCID model of acute wound with the formation of a functional dermal-epidermal junction. Together, these results show the positive impact of fibrin matrices and their released growth factor on epidermal substitute phenotype and grafting efficiency. Fibrin matrices, and especially hPBM, may therefore be of interest to favor the treatment of full-thickness burn patients.

Preserving the extra cellular matrix is critical for improving efficacy of keratinocyte sheets for treatment of burn wounds

IntroductionCultured autologous keratinocyte sheets (KS) have been proposed for treating burn wounds for over 30 years; however, they have not been translated to clinical practice because of negative effects of enzymes, used for detachment, on KS quality. The aim of this study was to test the hypothesis that non‐enzymatically detached KS exert better effects on grafted burn wound healing compared to enzymatically detached KS.MethodsFor non‐enzymatic detachment, autologous ovine primary keratinocytes were cultured in novel temperature‐responsive dishes (T sheets), and were detached by temperature reduction to 20°C. For comparison, the aliquots of keratinocytes were also cultured in conventional dish to be detached by use of enzyme (Dispase) (D sheets). We have tested the efficacy of these sheets using a well‐characterized, novel and clinically relevant ovine model of grafted burn wounds. Briefly, six full thickness skin burns (5×5cm) were induced in sheep dorsum under anesthesia and analgesia. After 24 hrs, burned skin was excised and wounds were grafted with ovine cadaver skin. After 3 weeks, rejected cadaver skin epidermis was debrided and wounds were covered with T and D sheets. Thereafter, the wounds were assessed for two more weeks. Wound samples were collected postmortem for various assays. The autologous keratinocytes for the sheet culture were isolated at the same day of skin grafting which mimics the clinical situation.ResultsCultured keratinocytes in both dishes formed firm sheets within three weeks, mimicking the time of cadaver skin epidermis rejection. Keratinocyte sheet thickness was significantly higher in T sheets compared to D sheets. In vivo, T sheets were better accepted with significantly higher wound re‐epithelialization percentage than D sheets at days 7 and 14 after sheet grafting. Although the epidermis thickness was comparable in wounds treated with both types of sheets, the dermal‐epidermal junction was well defined in wounds covered with T sheets at 14th day as evidenced by continuous lamina densa and high number of hemi‐desmosomes. Histopathological evaluation for burn wounds revealed that wounds treated with T sheets had less hemorrhage, ulceration incidence and neutrophils infiltration.ConclusionNovel non‐enzymatic method for KS detachment provides better sheet quality and accelerates healing of grafted burn wounds.Support or Funding InformationShriner's Hospital for Children SHC85100 and SHC84050This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

355 Establishing Ovine Model of Burn Wounds Grafted with Cadaver Skin

Shortage in autograft skin to cover burn wounds require a frequent use of cadaver skin as a temporary cover. Cadaver skin graft prevents infection and dehydration and prepares the wound bed for subsequent skin autograft or application of autologous tissue engineered skin constructs. The aim of this study was to establish an ovine model of burn wound healing using ovine cadaver skin. Quality and efficacy of fresh and frozen cadaver skins were evaluated comparing to skin autograph. Cadaver skin samples were harvested from sheep used for different studies at necropsy. The cadaver skin preparation process consisted of 4 steps: preparation for recovery by wool shaving and applying primary disinfection, collection, disinfection, and cryopreservation. First, to fully characterize fresh and frozen cadaver skin, the harvested skin was evaluated based on microbial screening, skin thickness, viability, and cell proliferation in in vitrocondition. The froze skin was evaluated after 10 and 40 days of freezing. Then we compared acceptance/rejection of autograft, freshly prepared and frozen cadaver skins overlaid onto burn ovine wounds. Full thickness skin burns (5X5cm) were induced in sheep dorsum. After 24 hrs, burned skins were excised and wounds were allocated to following groups: 1) Fresh ovine cadaver skin, 2) Frozen cadaver skin, 3) Autograft, 4) No cover. Pictorial record and skin biopsies were collected 7, 14 and 20 days after grafting cadaver skin. Prepared cadaver (fresh & frozen) skins were negative for bacterial growth. Thethickness was comparable between the freshly prepared and frozen skins for 10 or 40 days. Significant reduction in skin viability was detected in frozen skin after freezing for 40 days. Histological analysis of burn wounds biopsies showed that skin autograft maintains normal skin structure at different time points. However, fresh cadaver skin graft showed signs (vacuoles in epidermis) of rejection starting from day 7 as evidenced by microscopic analysis. At day 14, the epidermis was mostly rejected, and the rejection was completed by day 20. Histologically, signs of immunoreaction and presence of many immune cells were noted. Frozen Cadaver skin followed the same pattern of fresh cadaver skin rejection rate. Viability of fresh frozen cadaver skin before grafting was significantly higher vs. frozen (40 days). However, on average both fresh or frozen ovine cadaver skins were rejected within 8.5 days that mimics rejection time in humans (~8.4 days), suggesting that ovine model of burn wound grafted with cadaver skin can successfully be used in burn wound research mimicking clinical scenario. Establishing a clinically relevant ovine model for burn wounds grafted with cadaver skin is a potential contribution to the burn research.

Topical aqueous extract of Ephedra alata can improve wound healing in an animal model

PurposeEphedra alata (E. alata) is perennial tough shrub plant that grows in Palestine and other regions. It is used often in folk's medicine for the treatment of various diseases. In this project, E. alata extract was tested for its ability to improve wound and burn healing. MethodsAn aqueous extract of E. alata was prepared and underwent several phytochemical analyses for the presence of the major classes of phytochemical compounds. After that, a polyethylene glycol-based ointment containing the extract of E. alata was prepared and its wound and burn healing activities were tested in-vivo using an animal model for deep wound and full thickness skin burn. The effect was compared against a placebo ointment. Skin biopsies were evaluated by a blinded clinical histopathologist, in addition to digital analysis. ResultsPhytochemical analysis demonstrated the presence of the major classes of phytochemical compounds in the prepared extract including flavonoids, alkaloids, phytosteroids, phenolic compounds, volatile oils and tannins. As compared to placebo ointment, E. alata ointment significantly improved the healing of the wound ulcers, whereas it showed no advantage on the quality of the healing of burn ulcers. ConclusionE. alata extract is rich in phytochemical compounds and can improve wound healing when applied topically.

The Use of Glabrous Skins Grafts in the Treatment of Pediatric Palmar Hand Burns

An often overlooked, yet useful, technique in the treatment of palmar hand burns is the use of glabrous skin grafting, particularly in dark-skinned individuals. Pediatric palmar burns are a particularly unique subset of burns. The typical split-thickness or full-thickness skin grafts leave a notably different skin texture and pigmentation. It is also known that the psychological aspects of a pediatric burn can be quite burdensome for a child as he or she progresses through childhood and adolescence. For a dark-skinned patient the placement a standard full-thickness skin graft in a nonpigmented palm provides for a constant reminder of a traumatic event. We report a case series of pediatric patients who were managed with glabrous skin grafting from the plantar aspect of the foot. A retrospective review of palmar skin burns requiring grafting at a single pediatric burn center experience over a 2 and a half year time period was performed. Seventeen patients were identified. Our treatment algorithm for deep partial thickness burns first relies on a combination of operative and nonoperative measures to expedite the demarcation of the burn injury. If the burn is full thickness in nature or if a lack of progression of healing is identified within the first 14 days of injury, then skin grafting is recommended. Our technique for performing the graft is described. The average age at time of surgery was 2.05 years (6 months to 6.8 years). Fourteen of the 17 patients had darker skin types (Fitzpatrick Type III-VI) and identified themselves as either Hispanic or African American. The average size of the area requiring skin graft after debridement was 0.94% total body surface area (0.5%-2.0%). Of the patients that were not lost to follow-up, 1 patient required additional grafting after developing a finger contracture for splint noncompliance. Aesthetically, the wounds went on to heal with an excellent pigment match and an inconspicuous donor site. In the management of deep-partial or full-thickness palmar skin burns in the pediatric population that require grafting, the use of plantar glabrous skin grafts offers a reliable option for coverage. The aesthetic and functional results are improved over standard techniques.

Effect of piracetam and nimodipine on full-thickness skin burns in rabbits.

The potential of several drugs for full-thickness skin burns has been investigated, but the treatment of such burns remains a challenge in plastic surgery. The present study was designed to determine the effect of systemic and topical administration of piracetam and nimodipine on full-thickness skin burn wound healing. A total of 36 New Zealand male rabbits were divided into six groups. Full-thickness skin burns were produced in all the groups, except the control group. Piracetam was administered systemically (piracetam-IV) and topically (piracetam-C) for 14 days, and nimodipine was administered systemically (nimodipine-IV) and topically (nimodipine-C) over the burn wounds for 14 days. The sham group underwent burn injury but was not administered any drug. After 21 days, gross examination and histopathological analysis were performed and the results were compared statistically. Nimodipine-C and nimodipine-IV had no effect on burn wound healing. However, both piracetam-IV and piracetam-C significantly enhanced the healing of the full-thickness skin burn wounds, although the latter was more effective, useful and practical in burn wound healing. The histopathological features of the wounds in the piracetam-C group were closer to those of the control group than those of the other groups. Piracetam-C rather than piracetam-IV may promote full-thickness burn wound healing in rabbits.