Objective:To evaluate the effect of exosomes derived from bone mesenchymal stem cells (BMSCs-EXO) on the postoperative cognitive function and silent infomation regulator 1 (SIRT1)/ nuclear factor kappa B (NF-κB) signaling pathway in aged mice.Methods:BMSCs-EXO were isolated by differential centrifugation method and then identified. Twenty healthy male C57BL/6 aged mice, aged 18 months, weighing 35-40 g, were divided into 4 groups ( n=5 each) using a random number table method: sham operation group (Sham group), operation group (O group), BMSCs-EXO group and EX527 (SIRT1 inhibitor)group. The abdomen regions were shaved for sterilization without exploratory laparotomy in Sham group. Exploratory laparotomy was performed in O group. BMSCs-EXO 50 μg was injected through the tail vein at 1 h before surgery in BMSCs-EXO group. EX527 5 mg/kg was intraperitoneally injected daily at 1-3 days before surgery, and BMSCs-EXO 50 μg was injected through the tail vein at 1 h before surgery in EX527 group. Morris water maze test was used to evaluate the learning and memory ability for 5 consecutive days staring from the 1st day after surgery. Mice were sacrificed at 1 h after the end of Morris water maze test on day 5 after surgery, and the hippocampal tissues were collected for observation of the pathological changes of hippocampal CA1 region and for determination of the expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and IL-1β mRNA (quantitative real-time polymerase chain reaction) and SIRT1 and NF-κB p65 (by Western blot). Results:Compared with Sham group, the escape latency was significantly prolonged, the times of original platform crossing were decreased, the swimming time spent in the original platform quadrant was shortened, the expression of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and IL-1β mRNA was up-regulated, the SIRT1 expression was down-regulated, the NF-κB p65 expression was up-regulated ( P<0.05), and the pathological changes of hippocampal tissues in CA1 region were found in O group. Compared with O group, the escape latency was significantly shortened, the times of original platform crossing were increased, the swimming time spent in the original platform quadrant was prolonged, the expression of TNF-α, IL-6 and IL-1β mRNA was down-regulated, the expression of SIRT1 was up-regulated, the expression of NF-κB p65 was down-regulated ( P<0.05), and the pathological changes of hippocampal tissues in CA1 region were significantly attenuated in BMSCs-EXO group ( P<0.05). Compared with BMSCs-EXO group, the escape latency was significantly prolonged, the times of original platform crossing were decreased, the swimming time spent in the original platform quadrant was shortened, the expression of TNF-α, IL-6 and IL-1β mRNA was up-regulated, the SIRT1 expression was down-regulated, the NF-κB p65 expression was up-regulated ( P<0.05), and the pathological changes of hippocampal tissues in CA1 region were accentuated in EX527 group. Conclusions:BMSCs-EXO can improve the postoperative cognitive function in aged mice, and the mechanism may be associated with the activation of SIRT1/NF-κB signaling pathway.