BDNF and Alzheimer disease: As Aβ accumulates, microglia and astrocytes become activated and release inflammatory cytokines, exacerbating neuroinflammation.91,92 Studies have found that intraventricular injection of bMSC-derived exosomes can reduce the expression of BACE, Aβ1-42, and p-tau in the hippocampus of AD mice, while upregulating the expression of BDNF.92 This treatment alleviates neuroinflammation, mitigates neuropathological symptoms of AD, and promotes neuronal regeneration.