The effect of source animal age, decellularization protocol, and sterilization method on bovine acellular dermal matrix as a scaffold for wound healing and skin regeneration.

BACKGROUND: Healing the full-thickness skin wounds has remained a challenge. One of the most frequently used grafts for skin regeneration is xenogeneic acellular dermal matrices (ADMs), including bovine ADMs. This study investigated the effect of the source animal age, enzymatic versus non-enzymatic decellularization protocols, and gamma irradiation versus ethylene oxide (EO) sterilization on the scaffold. METHODS: ADMs were prepared using the dermises of fetal bovine or calf skins. All groups were decellularized through chemical and mechanical methods, unless T-FADM samples, in which an enzymatic step was added to the decellularization protocol. All groups were sterilized with ethylene oxide (EO), except G-FADM which was sterilized using gamma irradiation. The scaffolds were characterized through scanning electron microscopy, differential scanning calorimetry, tensile test, MTT assay, DNA quantification, and real-time PCR. The performance of the ADMs in wound treatment was also evaluated macroscopically and histologically. RESULTS: All ADMs were effectively decellularized. In comparison to FADM (EO-sterilized fetal ADM), morphological, and mechanical properties of G-FADM, T-FADM, and CADM (EOsterilized calf ADM) were changed to different extents. In addition, the CADM and G-FADM were thermally more stable than the FADM and T-FADM. Although all ADMs were noncytotoxic, the wounds of the FADM, T-FADM, and G-FADM groups were contracted to almost 30.0% of the original area on day 7, significantly faster than the CADM (17.5% ± 1.7) and control (12.2% ± 1.59) groups. However, by day 21, all ADMs were mostly closed except for the untreated group (60.1 ± 1.8). CONCLUSION: Altogether, fetal source and EO-sterilized samples performed better than calf source and gamma-sterilized samples unless in some mechanical properties. There was no added value in using enzymatic treatment during the decellularization process. Our results suggest that the age, decellularization, and sterilization methods of animal source should be selected based on the clinical requirements.

Efficacy and Safety of 0.25% Timolol Gel in Healing Split-Thickness Skin Graft Site.

As a common intervention among burn patients, skin graft has some risks such as infections and delay of wound healing. The aim of this study was to assess the efficacy and safety of topical 0.25% Timolol Gel (TG) in promoting wound healing in split-thickness skin graft donor sites. We conducted a double-blind, randomized clinical trial to assess re-epithelialization time, the level of pain based on the Visual Analog Scale (VAS), and the wound infection incidence. The scar status was also evaluated by the Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS). Totally, 64 patients were randomly assigned to the study groups. The two groups showed a significant difference in healing time (14.5 ± 3.2 vs. 11.5 ± 2.3 days, P < 0.001). No infection occurred in either group, and 3 cases of transplant rejection were observed in the placebo group. The VAS was significantly different on days 1, 2, 3, 4, and 7 (P < 0.05). In the third month, the results showed a significant difference in terms of VSS (P = 0.005). Topical TG, due to its favorable effects on wound healing and pain reduction, can be administered as a therapeutic agent in patients with a skin graft.

A case series of concomitant burn and COVID-19.

BACKGROUND: The recently emerged severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) disease (COVID-19) has become a human pandemic. Heightened inflammation, vascular hyperpermeability, acute lung injury, coagulopathy, and cardiovascular abnormalities are among the SARS-CoV-2 infection-related complications. Major burn is also associated with metabolic derangements, vascular leak, and hemodynamic instability. Burn patients are at high risk for infections and developing sepsis. COVID-19 in burn victims might worsen the clinical outcome and make their medical management challenging. RESULT: Here, we present four cases of concomitant burn and COVID-19 with different degrees of complications. They had no (three out of four) or multiple (one out of four) baseline comorbidities and all were admitted to hospital for further management. Three out of four cases demonstrated acute respiratory failure and were intubated (no longer than 7 days). It seems that one of them had COVID-19 on arrival, the other apparently contracted at outside hospital, and the last two infected during the index hospitalization. CONCLUSION: Concomitant severe burn and COVID-19 might complicate the clinical presentation and hospital course. Such combination was associated with poor outcome in a case with baseline comorbidities, beyond what was expected from the severity of burn injury. However, a more comprehensive study with larger sample size is required to make a valid conclusion. With an ongoing COVID-19 global pandemic, SARS-CoV-2 infection might be a concurrent disease with other illnesses or traumas such as burn. This dictate multidisciplinary approaches to risk stratify, screen, assess, and manage coexisting diseases. Additionally, appropriate preparations and careful precautions need to be executed in burn units to prevent COVID-19 exposure and transmission to limit potential adverse outcomes.