Fabrication, characterization and evaluation of the efficacy of gelatin/hyaluronic acid microporous scaffolds suffused with aloe-vera in a rat burn model

Burn induced injuries are commonly encountered in civilian and military settings, leading to severe morbidity and mortality. Objective of this study was to construct microporous bioactive scaffolds of gelatin-hyaluronic acid suffused with aloe-vera gel (Gela/HA/AvG), and to evaluate their efficacy in healing partial-thickness burn wounds. Scaffolds were characterized using Fourier transform-infrared spectroscopy, Scanning electron microscopy, and Thermo-gravimetric analysis to understand intermolecular interactions and morphological characteristics. In-vitro fluid uptake ability and hemolytic index of test scaffolds were also determined. In-vitro collagenase digestion was done to assess biodegradability of scaffolds. Wound retraction studies were carried out in Sprague Dawley rats inflicted with partial-thickness burn wounds to assess and compare efficacy of optimized scaffolds with respect to negative and positive control groups. In-vivo gamma scintigraphy using Technetium-99m labeled Immunoglobulin-G ( 99m Tc-IgG) as imaging agent was also performed to validate efficacy results. Histological and immunohistochemical comparison between groups was also made. Scaffolds exhibited mircoporous structure, with pore size getting reduced from 41.3 ± 4.3 µm to 30.49 ± 5.7 µm when gelatin conc. was varied from 1% to 5%. Optimized test scaffolds showed sustained in-vitro swelling behavior, were biodegradable and showed hemolytic index in range of 2.4–4.3%. Wound retraction study along with in-vivo gamma scintigraphy indicated that Gela/HA/AvG scaffolds were not only able to reduce local inflammation faster but also accelerated dermis regeneration. Immunohistochemical analysis, in terms of expression levels of epidermal growth factor and fibroblast growth factor-2 also corroborated in-vivo efficacy findings. Gela/HA/AvG scaffolds, therefore, can potentially be developed into an effective dermal regeneration template for partial-thickness burn wounds.

The Efficacy of Silver-Based Electrospun Antimicrobial Dressing in Accelerating the Regeneration of Partial Thickness Burn Wounds Using a Porcine Model

(1) Background: Wounds with damages to the subcutaneous are difficult to regenerate because of the tissue damages and complications such as bacterial infection. (2) Methods: In this study, we created burn wounds on pigs and investigated the efficacy of three biomaterials: polycaprolactone-gelatin-silver membrane (PCLGelAg) and two commercial burn dressings, Aquacel® Ag and UrgoTulTM silver sulfadiazine. In vitro long-term antibacterial property and in vivo wound healing performance were investigated. Agar diffusion assays were employed to evaluate bacterial inhibition at different time intervals. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assays were used to compare antibacterial strength among samples. Second-degree burn wounds in the pig model were designed to evaluate the efficiency of all dressings in supporting the wound healing process. (3) Results: The results showed that PCLGelAg membrane was the most effective in killing both Gram-positive and Gram-negative bacteria bacteria with the lowest MBC value. All three dressings (PCLGelAg, Aquacel, and UrgoTul) exhibited bactericidal effect during the first 24 h, supported wound healing as well as prevented infection and inflammation. (4) Conclusions: The results suggest that the PCLGelAg membrane is a practical solution for the treatment of severe burn injury and other infection-related skin complications.

Comparison of the outcome of amnion versus conventional (Vaseline-impregnated gauze) dressing in superficial partial thickness burn patients in terms of healing time and mean pain.

Objectives: To compare the healing time and mean pain score of Amnion versus Conventional (Vaseline-impregnated gauze) dressing in superficial partial thickness burn patients. Study Design: Randomized controlled study. Settings: Plastic & Reconstructive Surgery Department, Jinnah Hospital & Burn Center, Lahore. Period: January 2018 to January 2019. Material & Methods: A total of 60 patients with superficial second degree burns full filling the inclusion criteria were recruited for the study. Subjects were divided into two groups randomly. All patients were followed up regularly and dressing was changed on alternate days in Group B (Vaseline-impregnated gauze) and only secondary dressing was changed in Group A (amnion) until the auto sloughage (self-removal) of amnion. Outcome variables i.e. pain during first dressing change and healing time were noted. Statistical analysis of data was done using SPSS version 22. Quantitative variables i.e. age, duration of burn, total body surface area, pain during dressing and healing time were presented as mean and standard deviation. Frequency and percentage was calculated for qualitative variables like gender. The pain during dressing change and healing time of both groups were compared for difference. Student’t’ test was applied to compare the outcome and p-value ≤0.05 was considered as significant. Results: Out of sixty cases, 18 (30.0%) were females and 42 (70.0%) were males, with female to male ratio of 1:2.3. Mean age of patients in group A was 33.0 ± 10.19 years and in group B was 33.73 ± 9.55 years. The mean pain score in group A (amnion group) was 1.93 ± 0.91 and in group B (Vaseline-impregnated gauze) was 3.33 ± 1.56 with p-value of 0.0001. The mean healing time in group A (amnion group) was 15.73 ± 2.79 days and in group B (Vaseline-impregnated gauze) was 22.80 ± 4.44 days with p-value of 0.0001. Conclusion: Amnion dressing in superficial partial thickness burn patients is more effective in terms of mean pain score and healing time as compared to conventional (Vaseline-impregnated gauze) dressing.

miRNAs as Regulators of the Early Local Response to Burn Injuries

In burn injuries, risk factors and limitations to treatment success are difficult to assess clinically. However, local cellular responses are characterized by specific gene-expression patterns. MicroRNAs (miRNAs) are single-stranded, non-coding RNAs that regulate mRNA expression on a posttranscriptional level. Secreted through exosome-like vesicles (ELV), miRNAs are intracellular signalers and epigenetic regulators. To date, their role in the regulation of the early burn response remains unclear. Here, we identified 43 miRNAs as potential regulators of the early burn response through the bioinformatics analysis of an existing dataset. We used an established human ex vivo skin model of a deep partial-thickness burn to characterize ELVs and miRNAs in dermal interstitial fluid (dISF). Moreover, we identified miR-497-5p as stably downregulated in tissue and dISF in the early phase after a burn injury. MiR-218-5p and miR-212-3p were downregulated in dISF, but not in tissue. Target genes of the miRNAs were mainly upregulated in tissue post-burn. The altered levels of miRNAs in dISF of thermally injured skin mark them as new biomarker candidates for burn injuries. To our knowledge, this is the first study to report miRNAs altered in the dISF in the early phase of deep partial-thickness burns.

Development of a Reproducible Porcine Model of Infected Burn Wounds

Severe burns are traumatic and physically debilitating injuries with a high rate of mortality. Bacterial infections often complicate burn injuries, which presents unique challenges for wound management and improved patient outcomes. Currently, pigs are used as the gold standard of pre-clinical models to study infected skin wounds due to the similarity between porcine and human skin in terms of structure and immunological response. However, utilizing this large animal model for wound infection studies can be technically challenging and create issues with data reproducibility. We present a detailed protocol for a porcine model of infected burn wounds based on our experience in creating and evaluating partial thickness burn wounds infected with Staphylococcus aureus on six pigs. Wound healing kinetics and bacterial clearance were measured over a period of 27 days in this model. Enumerated are steps to achieve standardized wound creation, bacterial inoculation, and dressing techniques. Systematic evaluation of wound healing and bacterial colonization of the wound bed is also described. Finally, advice on animal housing considerations, efficient bacterial plating procedures, and overcoming common technical challenges is provided. This protocol aims to provide investigators with a step-by-step guide to execute a technically challenging porcine wound infection model in a reproducible manner. Accordingly, this would allow for the design and evaluation of more effective burn infection therapies leading to better strategies for patient care.Graphical Abstract

Keratin-Alginate Sponges Support Healing of Partial-Thickness Burns

Deep partial-thickness burns damage most of the dermis and can cause severe pain, scarring, and mortality if left untreated. This study serves to evaluate the effectiveness of crosslinked keratin–alginate composite sponges as dermal substitutes for deep partial-thickness burns. Crosslinked keratin–alginate sponges were tested for the ability to support human dermal fibroblasts in vitro and to support the closure and healing of partial-thickness burn wounds in Sus scrofa pigs. Keratin–alginate composite sponges supported the enhanced proliferation of human dermal fibroblasts compared to alginate-only sponges and exhibited decreased contraction in vitro when compared to keratin only sponges. As dermal substitutes in vivo, the sponges supported the expression of keratin 14, alpha-smooth muscle actin, and collagen IV within wound sites, comparable to collagen sponges. Keratin–alginate composite sponges supported the regeneration of basement membranes in the wounds more than in collagen-treated wounds and non-grafted controls, suggesting the subsequent development of pathological scar tissues may be minimized. Results from this study indicate that crosslinked keratin–alginate sponges are suitable alternative dermal substitutes for clinical applications in wound healing and skin regeneration.

An unusual presentation to the burn’ unit – a cautionary tale

We report a case of a 34-year old female with systemic lupus erythematosus (SLE) and lupus nephritis who was referred to the regional burns service with a suspected contact burn to the left flank and hypogastrium from a hot water bottle. The patient had been applying a hot-water bottle to the area at night for pain relief and after 3-days she noticed a localised area of erythema which became larger and began to blister over a period of 5-days. The blistered areas were erythematous and wet, however the capillary refill time was sluggish. The lesion was initially diagnosed and treated as a superficial partial thickness burn that had developed secondary to prolonged contact with a hot water bottle. However, due to the history of immunosuppression as well as elements of the lesion being unusual for a burn, we consequently diagnosed this as herpes zoster infection. This case highlights the importance of always thinking of alternative diagnoses. There are several cases in the literature where shingles has been dangerously misdiagnosed, furthermore leading to patients being mistakenly treated and even operated on. In the early stages, abdominal shingles may present very similarly to superficial partial thickness burns, both with neuropathic pain, erythema and blistering. It is important for the burns surgeon to be aware of this diagnosis as a differential in atypical presentations, and to pay particular attention to the timeline of events is the key to diagnosis.