Figure 3.

Macrophage-derived exosomes in bone metabolism. Arrow represents “stimulatory modification;” the gray triangle means “enlarged display.” The structure of macrophage derived exosomes is phospholipid bilayer with a diameter between 30 and 150 nm. Macrophage derived exosomes contain miRNAs (such as mir-21, mir-155, and mir-5106) and alarmins (such as Annexin, Galectin, HSP, and Fibronectin), all of them can through diverses signal pathways or release relative cytokines to participate in variety organs metabolism, including bone remodeling.