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A novel model for cutaneous wound healing and scarring in the rat.

ABSTRACT

Current rodent models of wound healing and scarring are flawed due to rapid wound contraction and inconspicuous scarring after healing, which is not closely parallel to the physiological process in human. This study was designed to establish a novel model of wound healing and scarring in rats. Excisional wounds were generated in rat tail or dorsal skin and assessed in terms of histological changes and wound contraction 2, 10 and 16 days postinjury. After healing, rat tail scar was investigated for 24 consecutive weeks by histological and immunohistochemical (IHC) staining. Finally, a stretched scar model was generated in rat tail with high or low strain after re-epithelialization to mimic human hypertrophic scar (HS). The tail HS were subsequently analyzed by histological, IHC staining and mRNA quantification 0, 2, 6, 12 and 24 weeks after stretching. Compared with the dorsal wounds, a larger dermal gap percentage (p<0.05) and more pronounced granulation formation was found in rat tail wounds. Tail scars remained conspicuous and underwent maturation over 24 weeks after wound healing. In addition, high mechanical strain induced a significant increase in scar area (p<0.01), scar height (p<0.05), vessel density (p<0.01) and HS-related molecule expression as well as distorted collagen arrangement in rat tail scars. The rat tail model exhibits minor wound contraction and biological features analogous to both normotrophic scar and HS in human when generated with or without stretching respectively. It is a promising new model for future studies of both cutaneous wound healing and scarring.