Improved cardiac-specific delivery of RAGE siRNA within small extracellular vesicles engineered to express intense cardiac targeting peptide attenuates myocarditis

Small extracellular vesicles (sEVs) are nanometer-sized membranous vesicles secreted by cells, with important roles in physiological and pathological processes. Recent research has established the application of sEVs as therapeutic vehicles in various conditions, including heart disease. However, the high risk of off-target effects is a major barrier for their introduction into the clinic. This study evaluated the use of modified sEVs expressing high levels of cardiac-targeting peptide (CTP) for therapeutic small interfering RNA (siRNA) delivery in myocarditis, an inflammatory disease of heart. sEVs were extracted from the cell culture medium of HEK293 cells stably expressing CTP-LAMP2b (referred to as C-sEVs). The cardiac targeting ability of C-sEVs with the highest CTP-LAMP2b expression was >2-fold greater than that of normal sEVs (N-sEVs). An siRNA targeting the receptor for advanced glycation end products (RAGE) (siRAGE) was selected as a therapeutic siRNA and loaded into C-sEVs. The efficiency of cardiac-specific siRNA delivery via C-sEVs was >2-fold higher than that via N-sEVs. Furthermore, siRAGE-loaded C-sEVs attenuated inflammation in both cell culture and an in vivo model of myocarditis. Taken together, C-sEVs may be a useful drug delivery vehicle for the treatment of heart disease.