Dermal Fibroblasts from the Red Duroc Pig Have an Inherently Fibrogenic Phenotype

Abstract

Background The pathophysiology of hypertrophic scarring is unknown due in part to the lack of a robust animal model. Although the red Duroc pig has emerged as a promising in vivo model, the cellular mechanisms underlying Duroc scarring are unknown, and the size and cost of Duroc pigs are obstacles to their use. Given the central role of the dermal fibroblast in scarring, we hypothesized that dermal fibroblasts from the Duroc pig exhibit intrinsic differences in key aspects of the fibroblast response to injury compared to those from the Yorkshire pig, a same-species control that heals normally. Methods Duroc and Yorkshire dermal fibroblasts were isolated from uninjured dorsal skin. Actin stress-fibers and focal adhesions were visualized by immunocytochemistry and transmission electron microscopy. Cell migration was measured using a scratch wound-closure assay. Contractile function was assessed by collagen-gel contraction. Expression of scarring-related genes was determined by quantitative RT-PCR, and transforming growth factor beta 1 (TGF-B1) protein expression was determined by Western blotting. Results Duroc dermal fibroblasts display increased adhesion-complex formation, impaired migration, enhanced collagen contraction, and pro-fibrotic gene- and protein-expression profiles compared to Yorkshire fibroblasts at baseline. In addition, Duroc fibroblasts over-expressed TGF-β1 and were less responsive to exogenous TGF-β1. Conclusions Duroc dermal fibroblasts have inherent myofibroblastic differentiation that may account for the pathologic scarring in these animals. Our data further validate the Duroc model and support Duroc fibroblast cell culture as a simple, inexpensive, reproducible, and biologically tractable in vitro model for the study of fibroproliferative scarring.

Hypertrophic scarring: the greatest unmet challenge after burn injury

“…The female (or castrated male) red Duroc pig develops hypertrophic scar following excisional or burn wounding. 69–74 This model is used to study the ontogeny of hypertrophic scar and intervention efficacy. 74 Another exciting development has been the grafting of human scar tissue onto the backs of immune-compromised mice; this model has facilitated studies of the scarring process itself, including the role of immune cells in hypertrophic scar by utilizing animals with various immune cells knocked out.…”

Imaging mass spectrometry for accessing molecular changes during burn wound healing

“…This study marks a preliminary foray toward the elucidation of novel biomarkers that are likely to shed light on the unwanted sequelae in human burn victims that nearly always result in hypertrophic scarring that persists for a lifetime. While porcine‐based reports based on the use of the red Duroc swine model have been used in recent years to evaluate scar formation, such studies are extremely expensive due to their long term housing costs . Smaller murine models of fibrosis have had limited utility to date and models using human skin transplanted onto immunocompromised mice have a limited ability to study the local burn wound in the context of the human systemic inflammatory response .…”

“…While porcine-based reports based on the use of the red Duroc swine model have been used in recent years to evaluate scar formation, such studies are extremely expensive due to their long term housing costs. 13,14 Smaller murine models of fibrosis have had limited utility to date 12 and models using human skin transplanted onto immunocompromised mice have a limited ability to study the local burn wound in the context of the human systemic inflammatory response. 27 Thus, to date, the elucidation of the molecular disturbances within human hypertrophic scars has been piecemeal and based largely on serendipity.…”

“…While circulating mediators and cells that affect patients from a global and systemic basis have been examined, global proteomic examination of local skin responses in patients after thermal injury have not been reported. Historically work with burned skin has used available techniques and tools that represent a reductionist type of approach that are focused on the role of individual or several mediators or used skin tissue from animal models …”

“…Historically work with burned skin has used available techniques and tools that represent a reductionist type of approach that are focused on the role of individual or several mediators [6][7][8][9][10][11] or used skin tissue from animal models. 7,[12][13][14][15][16] Recovery from thermal damage of the skin is a long, painful process that is often complicated by infection, a massive systemic inflammatory response, and the need for replacement of irreparably damaged skin. Eventually (especially in younger burn victims) significant hypertrophic scarring develops in the burned area and the negative sequelae can affect function as well as the psychological well-being of its victims.…”