Analysis of osteogenic and adipogenic ability. Adipose-derived stem cells (ADSCs) or bone marrow mesenchymal stem cells (BMSCs) were incubated with or without SPIOs (50 ng/ml). (a) Activity of ALP in two kinds of cells after osteogenic induction. (b) Real-time PCR analysis of BGP-mRNA after osteogenic induction. (c) OD value of lipid droplets after adipogenic induction. (d) Expression of aP2-mRNA after adipogenic induction.