A Mechanically Stimulated Co-culture in 3-Dimensional Composite Scaffolds Promotes Osteogenic and Anti-osteoclastogenic Activity and M2 Macrophage Polarization

This study investigates how mechanical stimulation modulates osteogenesis, osteoclastogenesis, and immunomodulatory behavior within 3D co-culture systems. Composite scaffolds consisting of PCL/nHA and PCL/β-TCP were seeded with bone marrow–derived mesenchymal stem cells (MSCs) and RAW264.7 macrophages to evaluate how mechanical loading influences cell fate and cross-talk. Cyclic compression significantly enhanced osteogenic gene expression, ALP activity, and mineral deposition in MSCs, while simultaneously suppressing osteoclast differentiation markers such as TRAP and CTSK in RAW264.7 cells. Mechanical loading also shifted macrophages toward an M2 repair-associated phenotype, increasing IL-10 and Arg-1 expression. In vivo implantation revealed superior bone formation and reduced inflammatory signaling in mechanically preconditioned scaffolds. These findings demonstrate that mechanical conditioning synergistically promotes osteogenesis while suppressing osteoclast and inflammatory activity, offering a powerful strategy for bone regeneration.