Multifunctional miRNA Delivery Systems Provide Synergistic Neuroprotection against Cerebral Ischemic Reperfusion Injury

Effectively alleviating cerebral ischemia-reperfusion (I/R) injury is challenging despite medical advances. Prompt restoration of blood flow after ischemic stroke causes secondary damage to brain tissue, triggers neuroinflammation and overproduces reactive oxygen species (ROS). MiRNA regulates genes involved in neuron apoptosis and neuroinflammation, thus exhibiting potential in ameliorating cerebral I/R injury. However, as miRNA is vulnerable to degradation, its effective delivery poses obstacles to clinical applications. Inspired by therapeutic potential of miR-210 inhibitors in ischemic stroke-induced neuroinflammation, we constructed a multifunctional nanosystem composed of ceria nanozymes and zeolitic imidazolate framework-90 (ZIF-90) nanoparticles to deliver miR-210 inhibitors to treat cerebral I/R injury. Attributed to proton sponge effect of ZIF-90, this nanosystem allows for lysosome escape of miR-210 inhibitors to protect their intracellular bioactivity, while integration of ZIF-90 and ceria nanozymes utilizes multi-enzyme cascade activities to constrain lipid peroxidation and reduce oxidative damage in brain tissues of mice with middle cerebral artery occlusion (MCAO). After crossing the blood-brain barrier, miR-210 inhibitors target TET2 to suppress pro-inflammatory cytokines, finally inhibiting neuroinflammation. More than uncertain stability and efficacy of direct TET2 protein administration, delivery of miR-210 inhibitors by multifunctional nanosystems engendered neuroprotection, indicating their potential for protein replacement therapy against cerebral I/R injury.