DNase I-Conjugated Cerium Oxide Nanoparticle-Based Treatment to Improve Thrombolysis

Ischemic stroke, caused by the occlusion of a cerebral artery by a thrombus, remains a major global health concern. While the recombinant tissue plasminogen activator (rtPA) is the only approved pharmacological treatment for thrombolysis, its limited efficacy stresses the pressing need for a more effective treatment. Neutrophil extracellular traps (NETs), derived from activated neutrophils and consisting of DNA (along with various proteins), contribute to thrombus resistance to rtPA-mediated thrombolysis. Additionally, rtPA-induced reperfusion can escalate oxidative stress, leading to cerebral hemorrhage. To address both oxidative stress and rtPA resistance in acute ischemic stroke, we thus propose to combine the antioxidant properties of cerium oxide nanoparticles (CNPs) with the DNase I enzyme targeting NETs’ DNA. For this purpose, CNPs were first coated with aminated polyethylene glycol (PEG) terpolymers to improve their colloidal stability and biodistribution. DNase I was then successfully grafted onto coated CNPs using EDC/sulfo-NHS chemistry. Once coated and functionalized, CNP@PEG-DNase retained its biological activities, effectively degrading both plasmid and fibrillar DNA and maintaining its antioxidant activity. In vitro studies showed that the functionalized CNPs did not impair the viability of brain endothelial cells (bEnd.3) and still reduced the reactive oxygen species (ROS) levels. In conclusion, PEG-coated CNPs functionalized with DNase I may facilitate rtPA-induced thrombolysis by degrading NETs and mitigate reperfusion-induced oxidative stress.