091 Low-Level Laser (650 nm) Stimulates Cell Growth and Downmodulates Prommp-1 and Timp-1 in Synchronized G0 Fibroblasts

Laser therapy has been considered useful for the treatment of chronic wounds. Different research groups have been working with fibroblastic metabolism, after culture irradiation with red and infrared sources of laser. Previously it has been demonstrated that lasers stimulate collagen synthesis and [3H]tymidine uptake when fibroblasts are irradiated and grown in the presence of fetal bovine serum (5–10%). Our group has been evaluating the in vitro effects of low-level laser (λ = 650 nm) activity on fibroblast metabolism. In this work, fibroblast activity was evaluated after 24, 48, and 72 h from G0 using synchronized fibroblast cultures previously irradiated with a single dose of low-level laser at different power densities (3.75, 7.5, 15, and 30 mW/cm2), during different times of exposure (15, 30, 60, and 120 sec). Proliferation was measured by [3H]tymidine uptake, and ProMMP-1 and TIMP-1 were evaluated by ELISA. Significant changes in proliferation were only observed after 48 h when "cultures were irradiated during 30 sec with 3.75, 7.5, and 15 mW/cm2, or during 60 seconds at 15 mW/cm2. However, ProMMP-1 diminished significantly after 24 and 48 h when cultures were irradiated with 7.5 and 15 mW/cm2 during 30 and 60 sec, and with 7.5 and 15 mW/cm2 during 15 seconds, after 48 h. TIMP-1 expression was significantly lower than the control during each dose and they were assayed 24 h after each irradiation. Based on the above data, fibroblast proliferation is stimulated 48 h after irradiation, using low-level laser to incorporate cells from G0 to the cell cycle, almost in the absence of serum (1%), although ProMMP-1 and TIMP-1 responses were observed 24 h after irradiation with the same doses. These results indicate that low-level laser can stimulate normal human fibroblasts to reduce collagen turnover, and consequently can be useful to stimulate normal fibroblast activity in a wound. As a result, this therapy could be administered every 2 days and may be more effective.