Silver nanoparticles promote osteogenic differentiation of mouse embryonic fibroblasts in vitro.

OBJECTIVE: This study investigated if silver nanoparticles (AgNps) could promote the proliferation and osteogenic differentiation of mouse embryonic fibroblasts. METHODS: Mouse embryonic fibroblasts were divided into two groups: Group 1 cells were cultured in DMEM/F12 medium and Group 2 cells were cultured in osteogenic medium. Both groups were then treated with 16, 32, or 100 µM AgNps. Fibroblast proliferation and viability were measured using BrdU and MTT methods at varying time points. Alizarin red staining and alkaline phosphatase (ALP) activity were measured to observe fibroblast differentiation into osteoblasts. Proteomics (cytokine array) was used to detect 111 different cytokines during differentiation. RESULTS: AgNps stimulated proliferation of mouse embryonic fibroblasts at a concentration of 16 µM. Marked enhancement of calcium mineralization was observed in cells cultured with AgNps compared with cells cultured without AgNps. Group 2 cells displayed nodules around the center where the cell density was high. ALP activity of mouse embryonic fibroblasts cultured in osteogenic medium increased during the whole culture period. Addition of AgNps at concentrations of 32 µM and 100 µM induced higher ALP activity at days 7 and 14. Proteomic array results show that low density lipoprotein receptor (LDL-R) and proprotein convertase subtilisin/kexin type 9 (PCSK-9) were significantly increased, while osteoprotegerin (OPG) was significantly reduced in medium containing 16 µM AgNPs. CONCLUSION: AgNps could promote differentiation of mouse embryonic fibroblasts into osteoblastic cells. LDL-R and PCSK-9, as well as OPG, may play a critical role in this process.