Hydrogen inhibits the osteoclastogenesis of mouse bone marrow mononuclear cells

Hydrogen (H₂) is one of the major biodegradation products of magnesium (Mg) alloys implanted for bony fracture healing and reconstruction; H₂ thus plays a significant role in the regulation of local microenvironment and the biology of resident cells. The interactions between the H₂ and the local cells are of great interest, and a full understanding of the effect of H₂ on bone marrow mononuclear cells (BMMCs) would accelerate the development of effective strategies for successful bony healing. This study investigates how H₂, with different concentrations and durations, regulates the osteoclastogenesis of mouse BMMCs. First, using H₂ with five concentrations (0%, 2%, 25%, 50% and 75%) and three durations (5, 7 and 10 days), the osteoclastogenesis of mouse BMMCs in these H₂ conditions were measured using TRAP staining, F-actin ring formation assay, pit formation assay and RT-qPCR analysis. Based on these findings, the proliferation assay, apoptosis assay, western blot analysis and ELISA assay of BMMCs after osteoclast induction were performed. The findings showed that H₂ (especially the 50% and 75% H₂) obviously inhibited the osteoclast formation, function and osteoclast-related genes expression of osteoclast-induced BMMCs; additionally, H₂ (50%) was found to reduce the proliferation, promote the apoptosis and inhibit the expression of osteoclast-related proteins of BMMCs with the presence of osteoclast-induced medium. Therefore, H₂ significantly inhibited the osteoclastogenesis of mouse BMMCs, which may become a new therapeutic agent for anti-bony resorption and open new avenues for the translational research of Mg alloys.