The effect of superpulsed carbon dioxide laser energy on keloid and normaldermal fibroblast secretion of growth factors: A serum-free study

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.