Photobiomodulation on human osteoblasts and osteogenic differentiation of adipose-derived stem cells

Abstract

The present in vitro comparative study evaluated parameters of osteogenesis under the influence of photobiomodulation (PBM). PBM uses light in the visible and near-infrared spectrum to induce a non-thermal process and to activate endogenous chromophores, whichmayresultintherapeuticoutcomes. Althoughthecellularandmolecular mechanisms involved in the PBM are still unclear, studies suggest that reactive oxygen species (ROS) produced in response to PBM, can induce activation of many biological pathways. Adipose-derived stem cells are promising for use in regenerative medicine and promoting their osteogenic differentiation would be used in improving bone tissue healing and regeneration. The effects of PBM at two different wavelengths with three different energy densities on human osteoblasts and osteogenic differentiation of adipose-derived stem cells were investigated in this present study. Another purpose of the study was to associate the possible biostimulative effect of light with photosensitizers (PSs), which are light activated molecules that cause ROS generation. The cells were incubated with Indocyanine Green (ICG) and Methylene Blue (MB) prior to laser irradiation. Assays measuring the cell viability, cell proliferation, alkaline phosphatase activity (ALP), mineralization, ROS generation and osteoblast specific gene expressions were performed. The results of the present study showed that combined light and PS treatment does not result in a synergistic enhancement of PBM on cell viability and proliferation, but detailed analysis revealed that mineralization and ALP activity were altered following only light or photosensitizer mediated light applications. Whether biostimulative or inhibitory effect occurs after PBM and PS-combined PBM depends upon light dose and wavelength. The potential applications of PBM may be numerous but adequate and reliable evidence is necessary to recommend PBM for clinical use.|Keywords : Photobiomodulation, osteoblasts, osteogenic differentiation, adipose-derived stem cells, low-level laser light.