Curcumin-laden exosomes target ischemic brain tissue and alleviate cerebral ischemia-reperfusion injury by inhibiting ROS-mediated mitochondrial apoptosis

The pathogenesis of ischemic cerebrovascular disease has revealed that ischemia-reperfusion (I/R) injury often leads to aggravation of metabolic oxidative stress and blood-brain barrier (BBB) destruction, eventually causing secondary brain tissue damage. Accumulated reactive oxygen species (ROS) in focal ischemia activate mitochondria-mediated apoptosis and damage the BBB by degrading tight junction proteins (TJPs). Herein, we report macrophage-derived exosomes (Ex) loaded with curcumin (cur) as a multifunctional biomimetic delivery vehicle (Ex-cur) for targeting ischemic brain tissue and alleviating cerebral I/R injury by inhibiting ROS-mediated mitochondrial apoptosis in a transient cerebral ischemia rat model. The design principle relies on unique features of macrophage-derived exosomes and the natural ingredient cur. Specifically, cur can be entrapped within exosomes when incubated with murine macrophage RAW264.7 cells, and its stability is subsequently significantly improved. The resultant Ex-cur can target ischemic regions by leveraging the targeting migration capability of Ex driven by inflammation. Accumulated Ex-cur in ischemic regions is experimentally proven to be highly effective at reducing ROS accumulation by virtue of the antioxidant properties of cur. Using Ex-cur to down-regulate ROS accumulation in lesions, we alleviate BBB damage and suppress mitochondriamediated neuronal apoptosis, which is confirmed by a series of relevant protein analysis. These findings demonstrate good therapeutic efficacy of Ex-cur for treating I/R injury, providing experimental evidence for the potential clinical benefits of Ex-cur for other modes of neuroprotection.