Effects of 405/532/808 nm Low-Power Laser Irradiation on Human-Derived Glioblastoma and Mitochondrial Morphology

It has been reported that low-power laser irradiation (LLI) can modulate various biological processes including the cell proliferation. However, mechanisms underlying the LLI effects remain unclear. We have demonstrated the following effects using three types of LLIs: The blue 405 nm LLI caused the human-derived glioblastoma (A-172) to the cell death, green 532 nm LLI significantly promoted the cell proliferation, and near-infrared 808 nm LLI potentially suppressed the cell proliferation. To reveal the mechanism of wavelength-specific LLI effects, the present study was designed to examine those LLI effects with focusing on mitochondrial morphology. 532 nm LLI significantly increased a small and granule type of mitochondria while decreased a large fusion type of them, compared with those of control (non-LLI) group. In contrast, 808 nm LLI significantly decreased the former type of mitochondria while increased the latter type. In the case of 405 nm LLI application, it induced live (spindle-type) cells and also apoptotic (round-type) cells. Mitochondrial morphology in the spindle-type of cells showed almost the same tendency as 532 nm case. We conclude that the wavelength-specific LLI effects are based on the mitochondrial morphological changes.