Biological effects of low power laser irradiation on clonal osteoblastic cells (MC3T3-E1)

Cultured osteoblastic cells were studied to determine the effects of laser irradiation on their rates of proliferation, differentiation, and calcification. A continuous wave Helium-Neon laser with a wavelength of 632.8 nm was used for this study. Clonal osteoblastic cells (MC3T3-E1) were exposed to laser beam at various energy densities. The cell growth rate and DNA synthesis were increased by laser irradiation only in the growing phase of culture. During long-term culture, 45Ca accumulation was enhanced by laser irradiation at 1.0 J/cm2, with four sessions of irradiation resulting in a 46% increase over controls. In contrast, no significant increase in alkaline phosphatase activity was produced by laser irradiation. Electron microscopy revealed a tendency of enlargement of the Golgi apparatus in the laser-treated cells. These results suggest that laser irradiation photoactivates osteoblastic cells, accelerates osteoblastic cell growth and calcification in vitro, and therefore, may promote bone regeneration.