Mammalian retrovirus-like protein PEG10 packages its own mRNA and can be pseudotyped for intercellular mRNA delivery

PEG10 preferentially binds and facilitates vesicular secretion of its own mRNA. We show the mRNA cargo of PEG10 can be reprogrammed by flanking genes of interest with PEG10s untranslated regions. Taking advantage of this reprogrammability, we develop Selective Endogenous eNcapsidation for cellular Delivery by engineering both mouse and human PEG10 to package, secrete, and deliver specific RNAs. Together, these results demonstrate PEG10 as a modular platform suited for development as an efficient therapeutic delivery modality.