Abstract

Abstract Messenger RNA (mRNA) has emerged as an attractive therapeutic molecule for a plethora of clinical applications. For in vivo functionality, mRNA therapeutics require encapsulation into effective, stable, and safe delivery systems to protect the cargo from degradation and reduce immunogenicity. Here, a bioengineering platform for efficient mRNA loading and functional delivery using bionormal nanoparticles, extracellular vesicles (EVs), is established by expressing a highly specific RNA‐binding domain fused to CD63 in EV producer cells stably expressing the target mRNA. The additional combination with a fusogenic endosomal escape moiety, Vesicular Stomatitis Virus Glycoprotein, enables functional mRNA delivery in vivo at doses substantially lower than currently used clinically with synthetic lipid‐based nanoparticles. Importantly, the application of EVs loaded with effective cancer immunotherapy proves highly effective in an aggressive melanoma mouse model. This technology addresses substantial drawbacks currently associated with EV‐based nucleic acid delivery systems and is a leap forward to clinical EV applications.