Bone marrow mesenchymal stem cells‐derived exosomes reduce Aβ deposition and improve cognitive function recovery in mice with Alzheimer's disease by activating sphingosine kinase/sphingosine‐1‐phosphate signaling pathway

Exosomes are associated with the development and progression of Alzheimer's disease (AD), although the impact of these extracellular vesicles in brain pathological condition remains incompletely understood. Therefore, this study aimed to investigate the role and mechanism of exosomes signaling in AD. Double transgenic APP/PS1 mice were injected with bone marrow mesenchymal stem cells (BM‐MSCs)‐derived exosomes or combined with SKI‐Ⅱ (sphingosine kinase [SphK] inhibitor) or VPC23019 (sphingosine‐1‐phosphate [S1P] 1 receptor blocker). We observed the spatial learning and memory ability of mice, and assessed the levels of amyloid and proteins. We found that exosomes improved spatial learning and memory ability of APP/PS1 mice, and enhanced the expression of SphK1 and S1P1. Moreover, exosomes inhibited the levels of amyloid and enhanced the expression of NeuN in cortex and hippocampus of APP/PS1 mice. Exosomes repressed the levels of Aβ1‐40, Aβ1‐42, BACE1, and PS1, and promoted the expression of neprilysin in APP/PS1 mice. The influence conferred by exosomes was abolished by SKI‐Ⅱ or VPC23019. In conclusion, our article confirms that BM‐MSCs‐derived exosomes reduce Aβ deposition and promote cognitive function recovery in AD mice by activating SphK/S1P signaling pathway. Thus, our data suggest that S1P/SphK‐containing exosomes should be explored as potential AD cure.