Brain‐Targeted 9‐Phenanthrol‐Loaded Lipid Nanoparticle Prevents Brain Edema after Cerebral Ischemia‐Reperfusion Injury by Inhibiting the Trpm4 Channel in Mice

Abstract Brain edema robustly increases mortality and hinders functional recovery after acute ischemic stroke. However, there are currently no effective therapies available for treating or preventing it. The unchecked opening of the transient receptor potential M4 (TRPM4) channel results in an excessive influx of Na + and water, which contributes significantly to the formation of brain edema after ischemic stroke. 9‐phenanthrol (9‐Phe), a potent TRPM4 inhibitor, has limited clinical applicability due to its potential cytotoxicity and poor solubility. A brain‐targeting T7 (HAIYPRH)‐modified lipid nanoparticle (LNP) encapsulated 9‐Phe (9‐Phe@T7‐LNP) is designed and synthesized to improve the physicochemical properties and pharmacokinetic properties of 9‐Phe for treating brain edema in vivo. These results demonstrated that 9‐Phe@T7‐LNP can penetrate the intact blood‐brain barrier (BBB) in normal mice and target the brain parenchyma. Moreover, 9‐Phe@T7‐LNP effectively reduced infarct volume and brain edema, prevented neuronal loss and BBB disruption, improved survival, and facilitated neurological function recovery after transient middle cerebral artery occlusion in mice. Additionally, 9‐Phe@T7‐LNP scavenged oxygen‐free radicals and prevented neuronal apoptosis in cultured neurons subjected to oxygen and glucose deprivation/reperfusion. In summary, these findings showed that 9‐Phe@T7‐LNP holds strong potential as a promising targeted therapy for brain edema after stroke, providing superior pharmacological neuroprotection against brain edema.