Unlocking the potential of iron-containing mesoporous bioactive glasses: Orchestrating osteogenic differentiation in bone marrow mesenchymal stem cells and osteoblasts

Iron (Fe) is a crucial element in the human body, playing a significant role in bone metabolism. The release of Fe ions at bone defect sites can promote bone regeneration. In this study, we synthesized Fe -containing mesoporous bioactive glasses (Fe-MBGs) in SiO 2 -CaO-Fe 2 O 3 composition using a sol-gel method. Regardless of the amount of incorporated Fe 2 O 3 (up to 5 mol%), the Fe-MBGs maintained a mesoporous structure, and the inclusion of Fe 2 O 3 did not alter their amorphous characteristics. However, the presence of Fe 2 O 3 led to a reduction in both pore volume and specific surface area of Fe-MBGs. Notably, Fe-MBGs demonstrated degradability in physiological fluids and could sustain release of Si, Fe, and Ca ions. Higher concentrations of incorporated Fe 2 O 3 were found to reduce the degradation of Fe-MBGs. All Fe-MBGs exhibited favorable bioactivity, as evidenced by the rapid formation of hydroxyapatite when exposed to simulated body fluid. Fe-MBGs also demonstrated concentrationdependent effects on BMSCs and Saos-2 cells. Extracts of Fe-MBGs at 0.1 and 1 mg/mL exhibited non-cytotoxicity and promoted cell proliferation. Additionally, extracts of Fe-MBGs at 1 mg/mL significantly enhanced the alkaline phosphatase activity of BMSCs and Saos-2 cells, along with an upregulation of the expression of osteogenesis-related genes. These findings unlock the significant potential of Fe-MBGs as functional biomaterials for bone regeneration applications. The controlled release of Fe ions from these mesoporous bioactive glasses orchestrates osteogenic differentiation in bone marrow mesenchymal stem cells and osteoblasts.