Osteogenic differentiation of hMSCs by the osteogenic exosomes. A,a–j) Immunofluorescence staining of the osteogenic markers (COL‐1 [a–e]; OPN [f–j]) in the hMSCs showing the osteogenic differentiation on day 20 induced by hMSCs‐derived osteogenic exosomes (EXO‐D0, EXO‐D4, EXO‐D10, EXO‐D15, and EXO‐D20) and B) the osteogenic medium. The red color of the cells ([h–j] in [A]) treated with the EXO‐D10, EXO‐D15, and EXO‐D20 is much deeper than that of the cells in (f) and (g). Similarly, the red color of the cells ([h–j] in [B]) treated with the osteogenic medium is much deeper than the other control cells in (f) and (g). Blue (DAPI), nuclei; green (FITC), F‐actin; red (TRITC), OPN and COL‐1. k–o) Bright field images of the Alizarin Red staining for the osteogenesis of hMSCs induced by the osteogenic exosomes. The red deposit is the calcium nodule and indicated by the arrows. Scale bar: 100 µm.