Autologous Graft Thickness Affects Scar Contraction and Quality in a Porcine Excisional Wound Model

Abstract

Background:Texture, color, and durability are important characteristics to consider for skin replacement in conspicuous and/or mobile regions of the body such as the face, neck, and hands. Although autograft thickness is a known determinant of skin quality, few studies have correlated the subjective and objective characters of skin graft healing with their associated morphologic and cellular profiles. Defining these relationships may help guide development and evaluation of future skin replacement strategies.Methods:Six-centimeter-diameter full-thickness wounds were created on the back of female Yorkshire pigs and covered by autografts of variable thicknesses. Skin quality was assessed on day 120 using an observer scar assessment score and objective determinations for scar contraction, erythema, pigmentation, and surface irregularities. Histological, histochemical, and immunohistochemical assessments were performed.Results:Thick grafts demonstrated lower observer scar assessment score (better quality) and decreased erythema, pigmentation, and surface irregularities. Histologically, thin grafts resulted in scar-like collagen proliferation while thick grafts preserves the dermal architecture. Increased vascularity and prolonged and increased cellular infiltration were observed among thin grafts. In addition, thin grafts contained predominately dense collagen fibers, whereas thick grafts had loosely arranged collagen. α-Smooth muscle actin staining for myofibroblasts was observed earlier and persisted longer among thinner grafts.Conclusions:Graft thickness is an important determinant of skin quality. High-quality skin replacements are associated with preserved collagen architecture, decreased neovascularization, and decreased inflammatory cellular infiltration. This model, using autologous skin as a metric of quality, may give a more informative analysis of emerging skin replacement strategies.

Recipient wound bed characteristics affect scarring and skin graft contraction

“…It has been reported that autograft thickness is negatively correlated with contraction . We have observed the same phenotype, confirming that our porcine model faithfully replicates the human wound healing condition. We also correlated autograft thickness with levels of inflammatory infiltrate and with levels of α‐SMA‐expressing pericytes and myofibroblasts.…”

“…In this study, we examined the role of hypodermis in scarring and contraction following application of split thickness skin grafts. As we have previously shown, when skin grafts are grafted onto fat, the amount of contraction is negligible . This is in stark contrast to grafts grafted onto fascia: the thinnest grafts on fascia contracted up to 50% of their original size.…”

“…Over the course of 120 days, we monitored the status of the wound and contraction (Figure A). As we have previously shown, when STSGs are grafted directly onto fascia and compared to full thickness skin graft (FTSG), the amount of contraction is directly correlated with the thickness of the STSG . FTSGs demonstrate minimal or no contraction, while grafts of 6/1,000th in.…”

Multi-faceted enhancement of full-thickness skin wound healing by treatment with autologous micro skin tissue columns

“…The extracellular matrix components from MSTCs may also directly contribute to the construction of the neodermis, as it has been previously reported that about 90% of the dermal portions of minced STSGs were incorporated into the newly formed dermis (with the remaining 10% expelled through the neoepidermis) 34 . The reduced wound contraction is another indication that the dermal components in MSTC are able to impact wound remodeling, since wound contraction is inversely proportional to the amount of dermal tissue included in skin grafts 35 . The ability to reduce wound contraction is also a significant clinical advantage, since contracture can lead to significant functional impairments that often require additional surgical interventions.…”

The pig as a model system for investigating the recruitment and contribution of myofibroblasts in skin healing

“…46 Similarities between pig and human skin, wound models, wound sizes as well as methods of analysis employed are important variables that influence healing and myofibroblast physiology. 24,[47][48][49][50][51][52][53][54][55][56] Pig and human skin appear similar histologically, with human epidermis thickness ranging from $50 to 120 μm, compared to the pig at 30-140 μm. 57 Further parallels include dermal collagen structure, well-developed dermal papillary bodies as well as subdermal adipose tissue.…”