Compositional Optimization of CRISPR/Cas9 Lipid Nanoparticles for Efficient Knockdown of Target Genes

Efficient and safe delivery systems remain a major barrier to the clinical translation of CRISPR/Cas9 gene-editing technologies; among these, formulation optimization of lipid nanoparticles (LNPs) is a key approach to improve delivery performance. Here, we constructed an orthogonal formulation library of LNPs using the ionizable lipids 4A2C2C6-A8 and 4A2C2C8-A8 at varied molar ratios and screened for optimal compositions. We identified formulations that combined high editing efficiency with low cytotoxicity; in HeLa-Luc cells, the optimized formulation achieved >80% knockout of the luciferase reporter. Further physicochemical and functional investigations showed that LNPs with relatively high zeta potential, mean diameters near 200 nm, and appropriate internal hydrophobicity-when paired with superior cellular uptake and endosomal escape capabilities-synergistically enhanced delivery efficiency. Using the compositionally optimized LNP to codeliver Cas9 mRNA and an sgRNA targeting HSP47 (whose overexpression has been implicated in fibrosis), we achieved efficient protein-level knockdown of HSP47 in L929 cells. These results provide important guidance for formulation optimization of CRISPR/Cas9 LNPs and support their potential application in antifibrotic therapies.