A healing assessment of full-thickness burns compared to excisional wounds after meshed split-thickness skin grafting

Burn followed by excision has long been the primary method used to create burn injury in model organism systems. Forgoing the burn and creating an excisional injury to replicate the burn wound is an alternative model to study full thickness injury to the skin; however, it has yet to be investigated whether this method adequately mimics the clinical trajectory of a healing burn injury. We aimed to investigate this excisional model and compare it to the traditional burn followed by excision model to understand the impact of the initial burn injury and determine whether the excisional model is an adequate method for porcine burn injury research. For this study, porcine subjects received either a full-thickness burn followed by excision or a full-thickness excision wound only. Both models then underwent 4:1 meshed split-thickness autografting. Skin biopsies and digital photographs were taken over the next 14 days to evaluate healing, and non-invasive probes were used to evaluate scar characteristics four and seven weeks after initial injury. There was a significant difference between the burn + excision and excision= only groups in the early time points when measuring re-epithelialization, dermal thickness, rete ridge ratio, cellularity, and erythema. Considerably fewer differences were noted in these parameters at the later time points, indicating more similarity in later tissue remodeling and scar formation between these two groups. This study demonstrates that the rate of wound healing after excision and grafting differs between wounds with a preceding burn injury and those without. However, that difference fades as wound healing progresses through the scar remodeling phase. These findings suggest that the type of porcine model used to study burn wound healing after excision and grafting impacts initial healing processes which should be considered when selecting a model and comparing results among different studies.