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.