Targeting the mechanics-glycolysis-histone lactylation axis to rescue bone regeneration under insufficient mechanical stimulation.

Abstract

Mechanical signals are essential for bone homeostasis and regeneration. Reduced mechanical stimulation, such as that occurring during fractures, paralysis, or aging, leads to bone loss and impaired osseous repair. However, effective clinical strategies that restore osteogenesis by reactivating mechanotransduction remain limited. In this study, we investigated downstream pathways of mechanotransduction that regulate osteogenesis to identify potential therapeutic targets for bone regeneration. Our results show that mechanical stimulation enhances glycolysis in mesenchymal stem cells (MSCs), and the resulting lactate promotes osteogenic differentiation via histone lactylation. High substrate stiffness or pharmacological activation with rotenone increased glycolytic activity, whereas decreased stiffness suppressed it. Importantly, enhancing glycolysis with rotenone partially restored osteogenic capacity in MSCs under reduced mechanical input, as reflected by improved mineralized nodule formation and osteogenic marker expression. To translate these findings into a therapeutic strategy, we developed an inflammation-responsive hydrogel encapsulating rotenone, designed to release the drug in response to elevated matrix metalloproteinase (MMP) and lipase activity during inflammation. In a rat periodontal bone defect model characterized by insufficient chewing force stimulation, this hydrogel significantly enhanced bone regeneration by promoting MSC-mediated osteogenesis, thereby partially bypassing the requirement for direct mechanical stimulation. Collectively, these findings identify a "mechanics-glycolysis-histone lactylation" axis that regulates MSC osteogenesis and bone regeneration. By targeting a downstream metabolic effector of mechanotransduction, the rotenone-loaded hydrogel provides a potential strategy for enhancing osteogenesis and promoting bone defect repair under conditions of insufficient mechanical stimulation. STATEMENT OF SIGNIFICANCE: Insufficient mechanical stimuli during periodontitis, trauma or ageing undermine the osteogenic programme of mesenchymal stem cells, yet no clinical strategy reinstates this lost mechanotransduction. We reveal that the downstream axis that mechanical cue is transduced to promote osteogenesis: mechanical stimulation activates glycolysis to enhance the production of lactate, which enters the nucleus, installs histone lactylation and switches on osteogenic genes. By packaging the glycolytic activator rotenone into an MMP/lipase-responsive hydrogel, we stimulated this metabolic signal at the defect site and achieved significant periodontal bone regeneration in rats despite abolished chewing forces. The work converts an insight into targeting the "mechanics-glycolysis-histone lactylation" axis to rescues bone healing when mechanical loading is compromised.