Recent advances in mRNA vaccine delivery

In recent years, messenger RNA (mRNA) vaccines have been intensively studied in the fields of cancer immunotherapy and infectious diseases because of their excellent efficacy and safety profile. Despite significant progress in the rational design of mRNA vaccines and elucidation of their mechanism of action, their widespread application is limited by the development of safe and effective delivery systems that protect them from ubiquitous ribonucleases (RNases), facilitate their entry into cells and subsequent escape from endosomes, and target them to lymphoid organs or particular cells. Some mRNA vaccines based on lipid carriers have entered clinical trials. Vaccines based on polymers, while not as clinically advanced as lipid vectors, show considerable potentials. In this review, we discuss the necessity of formulating mRNA vaccines with delivery systems, and we provide an overview of reported delivery systems.