In summary, the present study shows that MSC-EVs treatment ameliorates the hippocampal neuronal deficits observed in cell model or APP / PS1 transgenic mice, and that the therapeutic mechanism is associated with the Nrf2 defense system in vitro and in vivo, suggesting that MSC-EVs can serve as functional nanotherapeutic agents in the treatment of AD. The gene discussed is APP; the disease is Alzheimer disease.