The effects of 780nm laser irradiation on osteoblast and osteosarcoma cell proliferation

Abstract

Abstract Background and Objective: Some studies have shown that low-level laser therapy (LLLT) is able to stimulate the osteogenesis of bone tissue, increasing osteoblast proliferation and accelerating fracture consolidation. It is also suggested that LLLT may have a biostimulatory effect in tumor cells. However, the mechanism by which LLLT acts on cells is not fully understood. The aim of this study was to investigate the effects of 670nm, 780 nm and 830 nm laser irradiations on cell proliferation of primary osteoblast (MC3T3) and malignant osteosarcoma (MG63) cell lines in vitro. Material and Methods: Neonatal, murine, calvarial, osteoblastic and human osteosarcoma cell lines were studied. A single laser irradiation was performed at three different wavelengths, at the energies of 0.5, 1, 5 and 10 J/cm2. Twenty-four hours after LLLT, cell proliferation and alkaline phosphatase assays were assessed. Results: Osteoblast proliferation increased significantly after 830nm laser irradiation (at 10 J/cm2) but decreased after 780nm laser irradiation (at 1, 5 and 10 J/cm2). Osteosarcoma cell proliferation increased significantly after 670nm (at 5 J/cm2) and 780nm laser irradiations (at 1, 5 and 10 J/cm2), but not after 830nm laser irradiation. ALP activity in the osteoblast line was increased after 830nm laser irradiation at 10J/cm2, whereas ALP activity in the osteosarcoma line was not altered, irrespective of laser wavelength or intensity. Conclusion: Based on the conditions of this study, we conclude that each cell line responds differently to specific wavelength and dose combinations. Further investigations are required to investigate the physiological mechanisms responsible for the contrasting outcomes obtained when using laser irradiation on cultured normal and malignant bone cells.