[libribook.com] Traumatic Scar Tissue Management 1st Edition

fibroblast growth factor (FGF), epidermal growth factor (EGF), TGF-β1 and
interleukin-1 (IL-1). These and other inflammatory mediators (e.g. chemokines,
cytokines and substance P) are responsible for the typical cascade of events
associated with inflammation response.
As this reactive stage begins to subside, inflammatory mediators and the number
of neutrophils and macrophages are reduced at the wound site. The scarred area
may still be edematous, presenting as red in color with a noticeable rise in
temperature from surrounding tissue. The immune system remains active until
the barrier is repaired. Under normal circumstances this stage typically lasts
from 1 to 4 days – with the overt signs of edema beginning to diminish.
Stage 3: Proliferation
Within 48–72 hours after the initial injury, the healing process moves into the
proliferation stage. Endothelial cells and fibroblasts are the most prominent cell
types present in this stage, which, generally overlapping with the inflammatory
stage, is characterized by epithelial proliferation and fibroblast migration toward
the provisional matrix (i.e. first signs of scar formation – granulation tissue)
(Bordoni & Zanier 2014, Bran et al. 2012). Granulation tissue comprises
procollagen, elastin, proteoglycans (PGs) hyaluronan (HA), forming a structural
repair framework to bridge the wound and allow vascular ingrowth (Reinke &
Sorg 2011).
In addition to their role in collagen proliferation, cytokines (e.g. TGF-β1) also
stimulate the release of collagenase – intended to degrade the fine Type III
collagen that helped form the provisional matrix (Slemp & Kirschner 2006).
At this point in the healing process a stronger matrix replaces the provisional one
that was necessary to establish homeostasis. Fibroblasts stimulate Type I
collagen proliferation as well as glycosaminoglycans (GAGs) and PGs forming a
sturdier structural matrix – one that will better support day-to-day function.
If the wound is not too deep (i.e. has not damaged some or all of the nerve,
muscle, lymph, hair and sebaceous glands), fresh capillary beds form thus
constituting the hypervascularization seen in the early stages of wound healing.
Increased vascularity assists the formation of granulation tissue that begins the
process of restoring damaged tissue. Granulation tissue contains fibroblasts,
which synthesize mucopolysaccharides and collagen fibers that are necessary for
the development of new connective tissue.