Scar formation following excisional and burn injuries in a red Duroc pig model

Abstract

Scar research is challenging because rodents do not naturally form excessive scars, and burn depth, size, and location cannot be controlled in human longitudinal studies. The female, red Duroc pig model has been shown to form robust scars with biological and anatomical similarities to human hypertrophic scars. To more closely mimic the mode of injury, recreate the complex chemical milieu of the burn wound environment and enhance scar development, an animal model of excessive burn-induced scarring was developed and compared with the more commonly used model, which involves excisional wounds created via dermatome. Standardized, full-thickness thermal wounds were created on the dorsum of female, red Duroc pigs. Wounds for the dermatome model were recreated using two different total dermatome settings: ~1.5 mm and > 1.9 mm. Results from analysis over 150 days showed that burn wounds healed at much slower rate and contracted more significantly than dermatome wounds of both settings. The burn scars were hairless, had mixed pigmentation, and displayed four-fold and two-fold greater excess erythema values, respectively, compared with ~1.5 mm and > 1.9 mm deep dermatome injuries. Burn scars were less elastic, less pliably and weaker than scars resulting from excisional injuries. Decorin and versican gene expression levels were elevated in the burn group at day 150 compared with both dermatome groups. In addition, transforming growth factor-beta 1 was significantly up-regulated in the burn group versus the ~1.5 mm deep dermatome group at all time points, and expression remained significantly elevated versus both dermatome groups at day 150. Compared with scars from dermatome wounds, the burn scar model described here demonstrates greater similarity to human hypertrophic scar. Thus, this burn scar model may provide an improved platform for studying the pathophysiology of burn-related hypertrophic scarring, investigating current anti-scar therapies, and development of new strategies with greater clinical benefit.

Regeneration of rete ridges in Lanyu pig (Sus scrofa): Insights for human skin wound healing

“…Our results show extreme scar formation in FT 25 mm wounds in the Lanyu pig, and this is in accordance with multiple studies . However, our results show no rete ridge or papillary dermis regeneration and this result is different than the Blackstone and Gallant studies.…”

“…However, our results show no rete ridge or papillary dermis regeneration and this result is different than the Blackstone and Gallant studies. Interestingly, wound contraction is greater in the anterior/posterior axis and this concurs with multiple studies . This contrasts to the mouse FT wound model where contraction is greater in the medial/lateral axis and delineates a significant difference in wound healing compared to the tight‐skinned mammal Lanyu pig.…”

“…Interestingly, two studies reported rete ridge regeneration after FT wounding in Red Duroc pigs . Gallant et al showed 2 cm 2 FT and deeper FT wounds healed with extreme contraction greater in the anterior/posterior than medial/lateral axis with hypopigmented scars in Red Duroc pigs, and Blackstone et al examined dermatome excisional 5 cm 2 PT (~1.5 mm) and FT (~19 mm) wounds and compared to FT 5 cm 2 FT burn wounds showed minimal (PT or FT) or extreme (burn) scar formation and contraction . These results are in concordance with the Lanyu pig FT wounds (Figures and ).…”

Accelerated Wound Closure of Deep Partial Thickness Burns with Acellular Fish Skin Graft

“…A limitation of this study was that scarring was not directly assessed and we can only infer the CTPs impact from the contraction results. An appropriate model for hypertrophic scarring would be to utilize Red Duroc swine that is well characterized and accepted in the burn community [ 30 , 31 , 32 , 33 ]. In addition, extending the length of the study to 90 or 120 days and assessing the wounds specifically for scarring by a modified patient and observer scar assessment scale (POSAS) or Vancouver scar scale, erythema, melanin, picrosirius red, contraction, and viscoelastic properties (elasticity, firmness, tonicity, and suppleness) would be recommended for any future experiments.…”

Early cessation of pressure garment therapy results in scar contraction and thickening

“…Prior to wounding, a 1x1 cm grid was tattooed on each side of the pig to track skin surface area increase with time. Thermal injuries were utilized to create full-thickness, cutaneous defects as scarring in porcine skin was previously reported to be exacerbated in burn injuries and to more closely mimic human hypertrophic scar compared to scars resulting from excisional injuries [ 13 ]. To create full-thickness burn wounds, a 1” x 1” custom metal stylus[ 14 ] was heated to 200°C and held against each side of the pig (N = 4 pigs) for 40 seconds.…”