Targeted elimination of senescent cells by engineered extracellular vesicles attenuates atherosclerosis in ApoE^-/- mice with minimal side effects

Senescent cells in plaques emerge as a detrimental factor for atherosclerosis (AS), for which targeted senolysis might be a promising therapeutic strategy. The development of safe and efficient senolytics for senescent cell eradication by targeted delivery is greatly needed. Methods: Pro-apoptotic intelligent Bax (iBax)-overexpressing plasmid was constructed by molecular cloning, in which Bax CDS was fused to miR-122 recognition sites. Extracellular vesicle-based senolytics (EV^iTx) were developed to be conjugated with magnetic nanoparticles on the surface, iBax mRNA encapsulated inside, and BAX activator BTSA1 incorporated into the membrane. EV^iTx was characterized, and in vivo distribution was tracked via fluorescence imaging. The therapeutic effects of EV^iTx on AS and its systemic side effects were analyzed in ApoE^-/- mice. Results: Magnetic nanoparticles, iBax mRNA and BAX activator BTSA1 were efficiently loaded into/onto EV^iTx. With external magnetic field navigation, EV^iTx was delivered into atherosclerotic plaques and induced significant apoptosis in senescent cells regardless of origins. Repeated delivery of EV^iTx via tail vein injection has achieved high therapeutic efficacy in ApoE^-/- mice. Notably, EV^iTx is inevitably accumulated in liver cells, while the iBax mRNA was translationally repressed by miR-122, an endogenous miRNA highly expressed in hepatocytes, and thus the liver cells are protected from the potential toxicity of Bax mRNA. Conclusion: Our work demonstrated that magnetic EV-based delivery of iBax mRNA and the BAX activator BTSA1, efficiently induced apoptosis in recipient senescent cells in atherosclerotic plaques. This strategy represents a promising treatment approach for AS and other age-related diseases.