Lipid nanoparticles for precision nucleic acid delivery: linking cellular engineering to organ-specific targeting.

Lipid nanoparticles (LNPs) represent clinically validated non-viral platforms for nucleic acid delivery, yet expanding their application toward precision gene therapy demands more than efficient particle formulation or tissue accumulation. Functional delivery requires navigating a sequential biological cascade: establishing biological access to target tissues, undergoing cell-specific uptake, escaping endosomal entrapment, and releasing intact cargo into the cytosol. Because each stage presents a distinct rate-limiting barrier, success at one step does not guarantee downstream therapeutic activity. This review provides a multiscale evaluation of LNP-mediated delivery, bridging ex vivo cellular engineering and organ-specific in vivo targeting. We first analyze how lipid composition, physicochemical properties, and cargo architecture dictate self-assembly and intracellular fate. For ex vivo applications-highlighting hematopoietic stem/progenitor cells and natural killer cells-we address the balance between high transfection efficiency and the preservation of cell viability, phenotype, and cytotoxic function. For in vivo platforms, we examine how administration routes, physiological barriers, and cellular accessibility govern delivery to the liver, spleen, pancreas, lung, kidney, and brain, emphasizing that bulk organ accumulation often masks poor intracellular bioavailability-particularly given that only 1-4% of internalized cargo reaches the cytosol. Finally, we organize these insights into a route-barrier-cell framework that evaluates biological access, cellular uptake, endosomal escape, and cytosolic activity as interconnected yet distinct performance metrics. Overcoming current translational hurdles-including species-dependent tropism, biological variability, repeated-dose immunogenicity, and manufacturing scalability-will be essential to transition LNPs from broad nucleic acid carriers into precision targeted therapeutics.