Fractal dimension analysis and surface topography mapping to investigate the effects of low-level laser therapy on the physical behavior of osteosarcoma MG-63 cells

Introduction : Previous studies indicated that the low-level laser therapy has an effective role in modulation behavior of human osteosarcoma cells, which leads to change of cell proliferation, differentiation and adhesion. The aim of this study was to evaluate the effects of low-level laser therapy on the biophysical behavior of osteosarcomas based on the surface topographic mapping and fractal dimension analysis. Materials and Methods : Human osteosarcoma MG-63 Cells were cultured in DMEM-F12 with 10% FBS and were exposed by laser beams after reaching to confluence of 80% in the fourth passage. The lasers with characteristics of 532nm with the power of 25mW, 650nm with powers of 3mW and 150mw and 780nm with the power of 70mW were implemented for irradiation within 8 minutes and cell proliferation was assessed 72h after exposure time. In the next step, cell size changes in three dimensions were evaluated by using surface topographic mapping with atomic force microscopy and confocal imaging and fractal dimension analysis was performed by using the processing of confocal images. Results: The laser irradiation causes significant changes in proliferation, height, perimeter and area of osteosarcomas. Moreover, except 3mW laser, all of them create significant changes in fractal dimension compared with the non-irradiated cells. Conclusion: Assessing the fractal dimension besides the evaluation of three-dimensional cell sizes can be considered as a reliable index for the prognosis of the osteosarcomas response to low-level laser therapy.