From formulation to patient: Challenges in the development of clinically applicable lipid nanoparticles

Lipid nanoparticles (LNPs) are among the few nanotechnology platforms that have successfully transitioned from the labora tory to the clinic, as demonstrated by their use in mRNA vaccines against COVID-19 and in treatments for hereditary liver diseases. This review aimed to critically examine the literature from 2020-2026 to assess the discrepancy between the physicochemical and computational parameters routinely used to evaluate LNP formulations and the biological outcomes that ultimately determine their therapeutic efficacy. The analysis covered six key areas of LNP development: microfluidic production, lyophilization, transdermal microneedle delivery, formulation optimization via machine learning, endosomal escape, and protein corona formation. The find ings indicate that manufacturing processes that are reliable at the laboratory or pilot scale frequently lose reproducibility when translated to production or industrial scale, while computational optimization models depend on datasets that are inherently biased toward successful formulations. Endosomal escape efficiency remains strikingly low - according to published data, only 1-2% of internalized siRNA reaches the cytosol, and none of the compared formulations exceeded 10% escape efficiency, despite differences in their physicochemical properties. The protein corona, which governs LNP biodistribution, is almost exclusively characterized using plasma from healthy volunteers, even though the target patient population differs in pathophysiological status - a factor that substantially influences nanoparticle distribution in vivo. Based on this analysis, further progress in LNP development appears to depend not only on novel technologies, but more critically on the systematic re-evaluation of unverified assumptions and the establishment of functional, biologically relevant validation as a standard for assessing LNP formulations.