Collagen
Production.
The stimulus for the fibroblast to begin
producing collagen appears to be fibroblast
stimulating growth factors released from macrophages
and platelets.
The rate of production of collagen is
dependent on a number of factors, the most important
being the adequacy of perfusion and nutrients for
energy and protein synthesis.
Adequate molecular O2 is essential
for a number of key steps in collagen metabolism.
In
the presence of adequate blood flow, the rate of
collagen production appears to be directly
proportional to the wound O2 tension
and adequate nutrients especially amino acids and in
anabolic stimulus to protein synthesis.
Ferrous iron, ascorbic acid, pyridoxal,
and copper are also specifically required for
collagen synthesis.
The
rate of collagen synthesis is maximal in the first 1
to 2 weeks and collagen deposition is maximal at 3
to 4 weeks.
Two
other factors, well known to modulate this phase,
are vitamin A and zinc. Vitamin A maintains and
restores (in the case of corticosteroids) the
inflammatory stimulus required to generate the
healing factors.
Zinc is a cofactor in a number of
enzyme systems including new protein production.
Interstitial
Matrix Synthesis:
The
interstitial matrix, also produced by fibroblasts
and other mesenchymal cells, appears to have an
extremely important influence over the architectural
structure and strength of the collagen fibers.
Proteoglycans, which are composed of a
protein core enclosed by glycosaminoglycans, are a
major component.
The end result is a firm, nonpliable wound as
the collagen fibers become bound into the more rigid
matrix. With
gradual scar maturation and remodeling, the
proteoglycan content decreases.
