Hypertrophic scar formation following burns and trauma: new approaches to treatment

Abstract

The authors examine the process of hypertrophic scar formation, the results of current treatments, and areas of research likely to lead to significant advances in the field.

Figure 1. Complications of Hypertrophic Scarring

(A) Hypertrophic scars begin as small cutaneous fibrotic regions (arrowheads), which develop into gross scars (arrows) over time. Scarring phenotypes vary widely between different parts of the body for reasons that are at present unclear. (B) Following burn injury, a patient shows severe joint contracture. (C) Radiograph of the same patient shows erosion of the bone secondary to disuse and contracture. After years of treatment and physical therapy, this patient will only regain minimal hand function.

Figure 2. Seed versus Soil

Cellular and noncellular factors both play a role during the process of scar formation. Local environmental factors such as mechanical forces, extracellular matrix structure and orientation, and oxygen tension act as cellular signals. These signals influence the migration, adhesion, extravasation, and proliferation of varied cell types. These cells respond and in turn alter the physicochemical environment in which they reside. Keratinocytes migrate and multiply, changing the mechanical structure along the wound margin. Fibroblasts increase matrix production and initiate remodeling. Endothelial cells take part in neovascularization and regulate the blood flow and oxygen tension in the wound. As these cells alter their environment, complex feedback mechanisms move the wound healing process through its normal inflammatory, proliferative, and remodeling phases. Aberrant wound healing occurs when environmental or cellular factors are altered. Increased mechanical tension or oxygen dysregulation, for example, can lead to a constitutively active proliferative phase, increased matrix deposition, and hypertrophic scar formation.