Assessment of Cytoskeleton and Endoplasmic Reticulum of Fibroblast Cells Subjected to Low-Level Laser Therapy and Low-Intensity Pulsed Ultrasound

摘要

Objective: The aim of the present study was to compare the effect of low-level laser therapy (LLLT) and low-intensity pulsed ultrasound (LIPUS) on the cytoskeleton and endoplasmic reticulum of L929 cells. Thermal and non-thermal physical mechanisms such as LLLT and LIPUS induce clinically significant responses in cells, tissues, and organs. Materials and Methods: L929 fibroblast cell cultures were irradiated with LLLT and subjected to LIPUS. Cultures irradiated with the laser (904nm) were divided into three groups: group I, control (no irradiation); group II, irradiated at 6J/cm2; and group III, irradiated at 50mJ/cm2. Cultures subjected to ultrasound were divided into five groups: group I, control (no LIPUS); group II, LIPUS at 0.2W/cm2 in pulsed mode at 10% (1:9 duty cycle); group III, LIPUS at 0.6W/cm2 in pulsed mode at 10% (1:9 duty cycle); group IV, LIPUS at 0.2W/cm2 in pulsed mode at 20% (2:8 duty cycle); and group V, LIPUS at 0.6W/cm2 in pulsed mode at 20% (2:8 duty cycle). Each group was irradiated at 24-h intervals, with the following post-treatment incubation times: 24, 48, and 72h. The effects of LLLT and LIPUS on the cytoskeleton and endoplasmic reticulum was evaluated by the use of fluorescent probes and with fluorescence microscopy analysis. Results: The results following LLLT and LIPUS demonstrate that ultrasound was more effective than laser on fibroblast cell cultures when the endoplasmic reticulum was assessed, whereas there was a better distribution of the filaments of the cytoskeleton in the cells subjected to laser irradiation. Conclusion: The study demonstrated that both LLLT and LIPUS promote changes on the cellular level. However, LIPUS was more effective than LLLT at the doses used here, as assessed by fluorescence microscopy, which revealed increased reticulum activity and increased protein synthesis. However, when the organization of actin filaments was assessed, LLLT achieved a better result.