Effect of Blended CO 2 and Erbium:YAG Laser Irradiation on Normal and Keloid Fibroblasts: A Serum-Free Study

Abstract

Objective: The purpose of this study was to determine the effect of combined CO₂ and Er:YAG laser irradiation on normal (NF) and keloid (KF) facial dermal fibroblast production of TGF-β1 and bFGF. Background Data: Keloids produce excess collagen. TGF-β1 is integral to the growth and stimulation of fibroblasts and collagen; bFGF inhibits collagen synthesis. TGF-β1 and bFGF production influence wound healing and may be manipulated by laser irradiation. Materials and Methods: Human normal fibroblasts (NF) and keloid fibroblasts (KF) (2 × 10⁴ cells/mL in serum-free media) were exposed to 1.7 J/pulse Er:YAG laser energy and CO₂ delivered at either 3 or 5 W and at a duty cycle of 25%, 50%, or 100%. TGF-β1 and bFGF were assayed using a quantitative ELISA. Results: KF demonstrated a statistically significant mean population doubling time (PDT) when compared with NF (p = 0.01). Irradiated KF and NF had longer PDTs than controls. All NF, excluding one irradiated group, and the three KF treated with 3 W secreted more bFGF than controls. Irradiated KF secreted less TGF-β1 than controls. Significance was reached with the two groups exposed to 3 W at a duty cycle of 25% and 50% (p = 0.04 and 0.05, respectively). All irradiated NF secreted less TGF-β1 than controls. Conclusion: The combined CO₂ and Er:YAG laser increased the release of bFGF, which has been shown to promote tightly organized collagen bundles, and decreased the concentration of TGF-β1, which has also been shown to promote fibrosis formation. This laser may have a future role in keloid treatment, as well as normal facial scar prevention.