Enhanced cytosolic RNA delivery through early endosome fusion-mediated release via probiotic-derived lipopolysaccharide (LPS)-incorporated vesicles

Achieving efficient and secure cytosolic delivery is crucial for RNA therapeutics. Presently, delivery systems predominantly attain cytosolic release through membrane rupture or destabilization of late endosomes and lysosomes. However, these approaches lead to restricted RNA release and undesirable cytotoxicity, ultimately diminishing therapeutic efficacy. Herein, we proposed an efficient strategy based on early endosome fusion-mediated release, employing probiotic-derived lipopolysaccharide (LPS)-incorporated vesicles to enhance RNA delivery. The LPS is derived from Escherichia coli Nissle 1917 (EcN) and has a high safety confirmed by the authoritative pyrogen test. The LPS-rich outer membrane vesicles (OMVs) and synthetic chimeric liposomes (LPS-Lips) are found capable of efficient cytosolic RNA delivery by using LPS to fuse with early endosomes, as evidenced by super-resolution and real-time imaging. The OMVs and LPS-Lips (containing 10 % and 30 % EcN-derived LPS) exhibit enhanced ability to deliver functional BCL-xL siRNA, leading to more significant gene silencing and cell apoptosis in comparison to the commercial Lipofectamine 2000 and RNAiMAX groups. The in vivo results demonstrate their superior efficacy on inhibiting tumor growth and prolonged survival time with enhanced safety. These findings highlight the early endosome fusion strategy with facilitated release efficiency and safety, offering guidelines for the rational design of enhanced RNA delivery systems.