Abstract
Pandemic of coronavirus infectious disease （COVID）-19 has exerted serious impacts on society and medical serves. Two messenger RNA （mRNA） vaccines were approved within one year after the outbreak of COVID-19, providing a hopeful solution to this issue. Meanwhile, Japan lags behind in vaccine development, which imposes economic burden and causes limited supply of vaccines. Along with vaccines for preventing infectious diseases, other medical fields are potential targets of mRNA therapeutics； successful outcomes have been reported in clinical trials of cancer vaccines and immunotherapy, genome editing, and protein replacement therapy, which will help to address medical issues associated with the declining birthrate and the aging population in the future. Japan has huge potentials to contribute to the field of mRNA vaccines and therapeutics, especially by utilizing its original technologies in drug delivery system （DDS）. Notably, DDS, as well as chemical modification of mRNA, has played substantial roles in the development of mRNA COVID-19 vaccines. This review focuses on mRNA delivery systems, including synthetic nanoparticles from lipids and polymers and nature-derived systems, such as extracellular vesicles and naked mRNA.
