Biocompatible custom ceria nanoparticles against reactive oxygen species resolve acute inflammatory reaction after intracerebral hemorrhage

Intracerebral hemorrhage （ICH） is a devastating subtype of stroke with a high mortality rate, for which there currently is no effective treatment. A perihematomal edema caused by an intense inflammatory reaction is more deleterious than the hematoma itself and can result in neurological deterioration and death. Ceria nanoparticles （CeNPs） are potent free radical scavengers with potential for biomedical applications. As oxidative stress plays a major role in post-ICH inflammation, we hypothesized that CeNPs might protect against ICH. To test this hypothesis, core CeNPs were synthesized using a modified reverse micelle method and covered with phospholipid-polyethylene glycol （PEG） to achieve biocompatibility. We investigated whether our custom-made biocompatible CeNPs have protective effects against ICH. The CeNPs reduced oxidative stress, hemin-induced cytotoxicity, and inflammation in vitro. In a rodent ICH model, intravenously administered CeNPs were mainly distributed in the hemorrhagic hemisphere, suggesting that they could diffuse through the damaged blood-brain barrier. Moreover, CeNPs attenuated microglia/macrophage recruitment around the hemorrhagic lesion and inflammatory protein expression. Finally, CeNP treatment reduced the brain edema by 68.4% as compared to the control. These results reveal the great potential of CeNPs as a novel therapeutic agent for patients with ICH.