A novel model of post-burn hypertrophic scarring in rat tail with a high success rate and simple methodology.

BACKGROUND

Hypertrophic scars present a serious concern after surgeries and trauma, particularly with the highest risk following burn injury. The current modeling methods usually involve relatively complicated surgical operations and special equipment, and have unstable reproducibility and reliability. This study aimed to establish a simple and reliable model of post-burn hypertrophic scarring in the rat tail.

METHODS

Wet gauze saturated with hot water (94-98 °C) was applied to the dorsal side of the rat tail for varying durations to induce burn injury. Wounds were left exposed until completely healed, and the optimal duration for scalding treatment was determined based on gross examination. Thereafter, the optimal scalding duration was used again to evaluate scar formation over time, which was tracked through hematoxylin-eosin (HE) and Masson staining, immunohistochemistry of scar-related proteins and number/distribution of vascular endothelial cells, and picrosirius red staining to measure the quantities and proportion of type I and III collagen.

RESULTS

The scalding duration which led to optimal post-burn scarring was 15 s, with an overall success rate of 87.5 %. Complete healing of the wound occurred after roughly 30 days, leading to the formation of scars grossly red in appearance, tough to the touch and raised compared to the surrounding skin. Microscopically, the epidermis and dermis of the scar were significantly thicker than normal rat tail skin, and the dermis of scar contained a large number of disorganized bundles of fine filamentous collagen. We also observed a significant increase in the number of TGF-β1-positive cells and capillaries in the dermis (p < 0.05). Picrosirius red staining showed that compared to type III collagen, the expression of type I collagen was more dominant in scar tissue, and was more finely distributed than in normal rat tail skin.

CONCLUSION

We successfully established a model for post-burn hypertrophic scarring, utilizing reliable and simple techniques and materials, which could simulate the biological characteristics of post-burn scarring. Our innovative model has the potential to facilitate the study of post-burn wound healing and scar formation.