Thermal injury model in the rabbit ear with quantifiable burn progression and hypertrophic scar

Abstract

Hypertrophic scar is a major clinical outcome of deep-partial thickness to full thickness thermal burn injury. Appropriate animal models are a limitation to burn research due to the lack of, or access to, animal models which address the endpoint of hypertrophic scar. Lower species, such as rodents, heal mainly by contracture, which limits the duration of study. Higher species, such as pigs, heal more similarly to humans, but are associated with high cost, long duration for scar development, challenges in quantifying scar hypertrophy, and poor manageability. Here, we present a quantifiable deep-partial thickness burn model in the rabbit ear. Burns were created using a dry-heated brass rod for 10 and 20 seconds at 90 °C. At the time of eschar excision on day 3, excisional wounds were made on the contralateral ear for comparison. Burn wound progression, in which the wound size expands over time is a major distinction between excisional and thermal injuries, was quantified at 1 hour and 3 days after the injuries using calibrated photographs and histology and the size of the wounds was found to be unchanged from the initial wound size at 1 hour, but 10% in the 20 seconds burn wounds at 3 days. A quantifiable hypertrophic scar, measured by histology as the scar elevation index, was present in both 20 seconds burn wounds and excisional wounds at day 35. ImageJ measurements revealed that the 20 seconds burn wound scars were 22% larger than the excisional wound scars and the 20 seconds burn scar area measurements from histology were 26% greater than in the excisional wound scar. The ability to measure both burn progression and scar hypertrophy over a 35-day time frame suits this model to screening early intervention burn wound therapeutics or scar treatments in a burn-specific scar model.

Imiquimod‐induced skin inflammation is relieved by knockdown of sodium channel Nax

“…The thickness of stratum corneum and the density of hair follicles in the skin of the inner rabbit ear are more similar to that of human skin compared to rodent skin . Furthermore, we have extensive experience in establishing models in the rabbit ear including wound repair, hypertrophic scar, and atopic dermatitis models . Here, we demonstrated that, following repeated challenges of IMQ, dermatosis that parallels human psoriasis emerged in rabbit ear skin characterized by excessive keratinocyte proliferation (acanthosis), insufficient keratinocyte differentiation (parakeratosis) and infiltration of inflammatory cells, including neutrophils, macrophages, T cells and mast cells.…”

miR-137 Inhibits Proliferation and Metastasis of Hypertrophic Scar Fibroblasts via Targeting Pleiotrophin

“…Each type of therapy usually requires multiple treatments and has some limitations. Thus, more convenient, effective, and safe methods for the treatment of hypertrophic scars are needed [3,4].…”

Animal Models of Burn Wound Management

“…Moreover, rabbit model has proven to demonstrate the involvement of leucine as an important amino acid in muscle anabolism that shows the similar kinetics and pattern of change post-thermal injury in human patients [50]. Recently, Friedrich et al have demonstrated a quantifiable deep partial-thickness burn model in the rabbit ear using a dry-heated brass rod for 10 and 20 seconds at 90°C, resulting in a measurable burn progression and minimization of burn healing by contraction [51]. This animal model could be an important new tool to guide the treatment strategies of burn hypertrophic scarring.…”