A Protocol for Modeling Human Bone Inflammation: Co-Culture of Osteoblasts and Osteoclasts Exposed to Different Inflammatory Microenvironments

Bone remodeling relies on the coordinated activity of osteoblasts (OBs) and osteoclasts (OCs). Disruptions in OB-OC balance can lead to diseases such as periodontitis, a chronic microbial-induced inflammatory disease. To investigate how inflammation affects OB-OC interactions, we standardized an in vitro 2D indirect co-culture system using primary human OB and OC precursors from peripheral blood mononuclear cells in a transwell setup, which allows paracrine signaling and separate analysis of each cell type. When exposed to bacterial lipopolysaccharides (<i>Aa LPS</i> and <i>E. coli LPS</i>) and proinflammatory cytokines (IL-6 and TNF-α), we observed that inflammatory stimuli significantly increased OC differentiation, particularly TNF-α, while <i>E. coli LPS</i> specifically suppressed OB activity as observed by the expression of key markers and cellular staining. These results demonstrate that microbial and host-derived inflammatory factors can differentially modulate bone cell behavior. This approach offers a physiologically relevant and ethically advantageous alternative to animal models to screen dual-targeted bone therapies to restore perturbed metabolism.