Lipid nanoparticles for mR delivery: from rational design and manufacturing to clinical translation

The clinical success of COVID-19 mRNA vaccines established lipid nanoparticles (LNPs) as a leading platform for in vivo RNA delivery, but their therapeutic potential extends far beyond vaccination. This review provides an integrated perspective on LNP-RNA medicines by linking five interconnected dimensions: historical development, RNA payload engineering, LNP design, manufacturing, and clinical translation. We summarize how nucleoside modification, RNA structural optimization, and emerging formats such as circular RNA and self-amplifying RNA have expanded the functional scope of therapeutic payloads. We then examine the design principles of LNPs, with emphasis on ionizable lipids, formulation composition, and microfluidic manufacturing as the basis for reproducible large-scale production. We further distinguish clinically validated applications, including hepatic RNA delivery and intramuscular mRNA vaccination, from newer but less mature directions such as protein replacement, in vivo gene editing, and in vivo CAR-T generation. Importantly, this review highlights the major barriers that now limit broader translation, including extrahepatic targeting, incomplete understanding of protein corona-mediated delivery, weak cross-species predictability, repeat-dosing challenges, and evolving regulatory requirements. Overall, this review defines the key principles and translational challenges that will shape next-generation LNP-RNA therapeutics. GRAPHICAL ABSTRACT HIGHLIGHTS Integrates historical milestones, RNA engineering, LNP design principles, and manufacturing into a unified framework for LNP-RNA therapeutics. Introduces clinically validated applications and emerging directions including protein replacement, in vivo gene editing, and in vivo CAR-T therapies. Identifies critical translational barriers limiting broader clinical adoption: extrahepatic targeting, incomplete understanding of structure-activity relationships, weak cross-species predictability, and repeat-dosing challenges.