Low-Level Laser Facilitating Proliferation, Migration, and Reactive Oxygen Species Production in L929 Mouse Fibroblasts

Background: Photobiomodulation therapy has been widely used in various branches of regenerative medicine because it has the advantages of noninvasive, drug-free, and safe form of light therapy. However, the complexity of the parameters of low-level laser (LLL) hinders its wider clinical application. Materials and Methods: Mouse fibroblasts (L929) were cultured in vitro using an 810-nm diode laser with low-level mode (E1C 0.1 W, continuous; E1R 0.1 W, intermittent; E2C 0.5 W, continuous; E2R 0.5 W, intermittent). Cell migration ability was detected by in vitro scratch test. Cell proliferation ability was detected by cell counting kit-8 (CCK-8) assay. Reactive oxygen species (ROS) fluorescence intensity was detected by an inverted fluorescence microscope. Production of ROS was detected by flow cytometry. Results: Scratch results show that E1C and E2R significantly increased the cell migration rate compared with the E0 group (p < 0.001). E1R also enhanced cell migration (p < 0.01). CCK-8 results show that the increase in the optical density of E1R, E1C, and E2R was higher than that of E0 (p < 0.001). The E2C group did not facilitate cell proliferation. The results of ROS fluorescence analysis and flow cytometry analysis showed that the ROS produced by L929 cells irradiated with different modes of LLL were different. The ROS production of E2C cells was the highest, followed by E2R, E1C, and E1R, and the E0 group was the lowest, with a significant difference (p < 0.01). Conclusions: An 810-nm diode laser of 0.1 W with continuous pulse mode and 2 cm away from the wound can maintain the appropriate level of ROS, as well as effectively promote cell proliferation and migration.