CA-20 is a bile acid-derived sterol designed to replace cholesterol in mRNA LNPs. It achieves high mRNA encapsulation efficiency up to 87.4% and forms uniform, spherical nanoparticles with ordered membrane structures confirmed by cryo-TEM and MD simulations. In vivo, CA-20 drastically cuts hepatic mRNA expression while shifting nearly all gene expression to the spleen, driven by reduced ApoE protein binding on LNP surfaces. Using HA mRNA vaccines, CA-20 LNPs trigger stronger antigen-specific IgG, neutralizing antibodies, memory B cells and IFN-γ-secreting T cells than cholesterol LNPs. Acute safety tests prove CA-20 causes minimal liver damage, with normal serum liver enzymes and intact organ histology, delivering balanced superior immunogenicity and low liver toxicity for spleen-targeted mRNA vaccine delivery.
