Amorphous Calcium Phosphate NPs Mediate the Macrophage Response and Modulate BMSC Osteogenesis

The potential risk associated with ACP nanoparticles (ACP NPs) cultured with immune cells and their indirect effects on osteogenesis have not been studied deeply. This project aims to evaluate the safety of ACP NPs in macrophages, the responses of macrophages (macrophage polarization, the cytokine secretion pattern of macrophages and intracellular homeostasis) to ACP NPs and the effect of ACP NPs/macrophage-modulated environments on the osteogenic ability of BMSCs. The cell proliferation rate and apoptosis were detected by CCK-8 and Annexin V Apoptosis Detection kits. ROS and autophagy expression were evaluated by ROS test kits and Western blot (WB). Macrophage polarization and cytokine expression were determined by SEM, cytoskeletal staining, RT-PCR and ELISA. TMT™ quantitative protein analysis was used to evaluate protein expression. BMSC osteogenic differentiation was detected by ALP staining, Alizarin Red solution staining and RT-PCR. ACP NPs were safe to macrophages but promoted autophagy and induced ROS production at high concentrations. ACP NPs changed morphology of macrophages and induced polarization into M1 type, thus promoting the expression of inflammatory cytokines. ACP NPs/macrophage-modulated environments weakened the osteogenic ability of BMSCs. ACP NPs polarize macrophages into the M1 phenotype and change the cytokine secretion pattern. ACP NPs/macrophage-modulated environments weaken the osteogenic ability of BMSCs. ACP NPs may cause aseptic inflammation and attenuate osteogenesis.