PSEN1 and Cognitive impairment: In another study, BM-MSC-derived exosomes suppressed the levels of Aβ1-40, Aβ1-42, β-amyloid precursor protein cleaving enzyme (BACE1), and presenilin 1 (PS1), while upregulating NeuN expression in cortex and hippocampus of treated mice, which led to improved cognitive impairment [150].