Kc. Nowak et al., The effect of superpulsed carbon dioxide laser energy on keloid and normaldermal fibroblast secretion of growth factors: A serum-free study, PLAS R SURG, 105(6), 2000, pp. 2039-2048
An in vitro model was used to determine the effect of superpulsed CO2 laser
energy on normal dermal and keloid-producing fibroblast proliferation and
release of growth factors. Growth factors assayed included basic fibroblast
growth factor (bFGF) and transforming growth factor pr (TGF-beta 1). bFGF
is mitogenic, inhibits collagen production, and stabilizes cellular phenoty
pe. TGF-beta 1 stimulates growth and collagen secretion and is thought to b
e integral to keloid formation. Growth in a serum-free medium allowed measu
rement of these growth factors without confounding variables.
Keloid and normal dermal fibroblasts cell lines were established from facia
l skin samples using standard explant techniques. Samples consisted of thre
e separate keloid and three separate normal dermal fibroblast cell lines. C
ells were used at passage 4 to seed 24-well trays at a concentration of 6 x
10(4) cells per milliliter in serum-free medium. At 48 hours, 18.8 percent
of each cell well was exposed to a fluence of 2.4, 4.7, and 7.3 J/cm(2) us
ing the superpulsed CO2 laser. Cell viability and counts were established a
t four time points: 0 (time of superpulsed CO2 laser treatment), 24, 72, an
d 120 hours. Supernatants were collected and assessed for bFGF and TGF-beta
1 using a sandwich enzyme immunoassay.
All cell lines demonstrated logarithmic growth through 120 hours (conclusio
n of experiment), with a statistically significant shorter population doubl
ing time for keloid fibroblasts (p < 0.05). Use of the superpulsed CO2 lase
r shortened population doubling times relative to that of controls; the dif
ferences were statistically significant in keloid dermal fibroblasts when f
luences of 2.4 and 4.7 J/cm2 were used (p < 0.05 and 0.01, respectively). b
FGF was present in greater levels in normal dermal fibroblasts than in kelo
id dermal fibroblasts. Application of superpulsed CO2 demonstrated a trend
toward increased bFGF secretion in both fibroblast types; the increase was
significant in the keloid group at 4.7 J/cm(2). A consistent trend in suppr
ession of TGF-beta I was seen in both groups exposed to superpulsed CO2, wi
th the maximal effect occurring at 4.7J/cm(2).
Serum-free culture sustains logarithmic cell growth and allows growth facto
r measurement without confounding variables from serum-containing media. Su
perpulsed CO2 enhances fibroblast replication and seems to stimulate bFGF s
ecretion and to inhibit TGF-beta 1 secretion. Given the function of these g
rowth factors, the application of superpulsed CO2 may support normalized wo
und healing. These findings may explain the beneficial effects of laser res
urfacing on a cellular level and support the use of superpulsed CO2 in the
management of keloid scar tissue.