Effects of Nd:YAG low-level laser irradiation on cultured human osteoblasts migration and ATP production: in vitro study

Low-level laser therapy has become one of the fastest growing fields of medicine in recent years. Many in vivo and in vitro studies have shown that laser irradiation activates a range of cellular processes in a variety of cell types and can promote tissue repair. However, few in vitro experiments have evaluated the effects of laser irradiation on cells in real time. The purpose of this study was to examine the effects of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser irradiation on the migration of cultured human osteoblasts. A dedicated 96-well plate was used, and confluent cultures of the human osteoblast-like cell line, Saos-2, were injured with a wound maker. The wounded cells were then exposed to the Nd:YAG laser (wavelength of 1064 nm) for 60 s at 0.3 W (10 pps, 30 mJ). The total energy density was about 10.34 J/cm 2 . Images of the wounds were automatically acquired inside the CO 2 incubator by the IncuCyte ZOOM™ software. In addition, after laser irradiation, the production of adenosine triphosphate (ATP) was measured using the CellTiter-Glo™ Luminescent Cell Viability Assay. Migration of cells from the border of the original scratch zone was accelerated by laser irradiation. In addition, compared with the control group, significant enhancement of ATP production was observed in the irradiated group. The present study showed that Nd:YAG laser irradiation (wavelength of 1064 nm, 0.3 W, 10 pps, 30 mJ, 10.34 J/cm 2 , irradiation time 60 s) may contribute to the regeneration of bone tissues owing to enhanced osteoblast cell migration.