Osteoporosis is one important manifestation of aging, and many studies have shed light on the decreased stemness of BMSCs and proved that multifarious mechanisms including signaling pathways including NAD+–Sirt1 [26] and Notch [27], miRNA [28, 29], and organelle dysfunction [30] contributed to the decline during cellular senescence. Here, SIRT1 is linked to osteoporosis.