Laser irradiation decreases sclerostin expression in bone and osteogenic cells

Abstract

Anti‐sclerostin monoclonal antibody romosozumab, a treatment for osteoporosis, reduced vertebral fracture risk and clinical fracture. Laser irradiation triggers various effects, including bio‐stimulation, which can induce beneficial therapeutic effects and biological responses. Originally, we performed in vivo experiments to clarify the mechanism of better bone healing in laser‐ablated bone. Here, we evaluated comprehensive and sequential gene expression in Er:YAG laser‐ablated, bur‐drilled, and nontreated control bones, and found laser irradiation suppressed Sost (coding protein: sclerostin) expression in the bone, possibly via stimulation of mechanotransducers. Surprisingly, bio‐stimulation effect of laser suppressed Sost expression in the primary osteogenic cells. Decreased sclerostin expression after laser irradiation was also validated both in vivo and in vitro. In addition, sequential microarray analysis revealed that the gene expression pattern was clearly different at 24 hours after bone ablation between bur‐drilled and laser‐ablated bones. The Hippo signaling pathway was significantly enriched, whereas inflammation‐related pathways were not affected at 6 hours after the laser ablation, indicating that laser irradiation caused mechanical stimulation. Only bur‐drilled bone showed enriched inflammation‐related gene sets and pathways at 24 hours, not in the laser‐ablated bone. Our study suggests that laser irradiation may become a new treatment modality for osteoporosis, by inhibiting sclerostin expression without inducing inflammation.

Current status of Er:YAG laser in periodontal surgery

“…Interestingly, in the laser-treated bone tissue, the irradiation increased Dmp1 expression, and suppressed Sost expression, the gene of Sclerostin that inhibits caronical wnt signaling pathway and suppresses new bone formation. They [56] also confirmed using primary rat osteogenic cells (osteocytes-like cells from osteoblast-like cells differentiation) that Er:YAG laser irradiation at 1.5 and 3.1 J/cm 2 decreased Sost expression in the cells and Sclerostin expression in the cultured supernatant, suggesting that Er:YAG laser irradiation may promote bone formation via the suppression of Sost expression.…”

Effects of Irradiation by Carbon Dioxide Laser Equipped With a Water Spray Function on Bone Formation in Rat Tibiae

“…Bone tissue shows splendid adaptability to mechanical stress, as revealed by Wollf's law (12). Our prior results on the effects of CO 2 laser irradiation on sclerostin expression in osteocytes showed that the effect of CO 2 laser irradiation on bone formation was the same as that of mechanical stress (13). CO 2 laser irradiation has been confirmed to induce bone formation,…”