BDNF and Alzheimer disease: lateral ventricle administration of BMSC-exos could improve ADlike behaviors, as indicated by the increased motion and rearing in the OFT, together with an increased preference index of novel objects in the NOR. Moreover, hippocampal inflammation and hyperactivation of glial cells in the AD mouse model were significantly improved, and the protein expression levels of BACE, Aβ1–42 and p-Tau were significantly reduced, while the expression level of BDNF was significantly increased. However, not caudal vein injection of BMSC-exos, can improve AD-like behaviors in