Effect of cerium ion on the proliferation, differentiation and mineralization function of primary mouse osteoblasts in vitro

The effects of cerium ion (Ce³⁺) on the proliferation, differentiation, adipocytic transdifferentiation and mineralization function of primary mouse osteoblasts (OBs) were investigated. The results indicated that Ce³⁺ at all concentrations (1 × 10^-9, 1 × 10^-8, 1 × 10^-7, 1 × 10^-6, 1 × 10^-5, and 1 × 10^-4 mol/L) promoted the proliferation of osteoblasts (OBs). On day 1 and 3, Ce³⁺ promoted the differentiation of OBs at concentrations of 1 × 10^-9, 1 × 10^-7, and 1 × 10^-6 mol/L, but inhibited the differentiation of OBs at higher concentrations. On day 2, Ce³⁺ inhibited the differentiation of OBs at tested concentrations. On day 9 and 12, Ce³⁺ inhibited the adipocytic transdifferentiation of OBs at most concentrations. On day 15, Ce³⁺ promoted the adipocytic transdifferentiation of OBs at concentrations of 1 × 10^-9, 1 × 10^-6, 1 × 10^-5, and 1 × 10^-4 mol/L, but had no effects at other concentrations. Ce³⁺ inhibited the formation of mineralized matrix nodules of OBs at concentrations of 1 × 10^-9, 1 × 10^-8 and 1 × 10^-7 mol/L, and promoted the formation of mineralized matrix nodules of OBs at other concentrations. These findings suggested that the effects of Ce³⁺ on the proliferation, differentiation, adipocytic transdifferentiation and mineralization function of primary OBs depended on the concentration and culture time; moreover, they were pivotal factors for switching the biological effects of Ce³⁺ from toxicity to activity, from damage to protection, or from down-regulation to up-regulation.