Engineered extracellular vesicles as nanosponges for lysosomal degradation of PCSK9

Abstract

Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a crucial role in degradation of low-density lipoprotein receptor (LDLR) and PCSK9 inhibition emerges as an attractive strategy for atherosclerosis management. In this study, extracellular vesicles (EVs) were engineered to nanosponges, which could efficiently adsorb and deliver PCSK9 into lysosomes for degradation. Briefly, nanosponges were engineered by modifying EVs with EGF-A/PTGFRN fusion protein (PCSK9 binding domain EGF-A from the mutant LDLR with higher affinity was fused to the C-terminus of Prostaglandin F2 Receptor Negative Regulator). The modification endowed the EVs with hundreds of EGF-A displayed on the surface and thus the capacity to adsorb PCSK9 efficiently. The adsorbed PCSK9 would thus be delivered into lysosomes for degradation when the nanosponges were endocytosed by liver cell, thus releasing endogenous LDLR from degradation. In ApoE^-/- mouse model, tail vein injected nanosponges were able to degrade PCSK9, increase LDLR expression, lower LDL-C level, and thus alleviate atherosclerosis. In summary, we here not only develop a novel strategy for PCSK9 inhibition, but also propose a universal method for adsorption and degradation of circulating proteins for disease management.