LIN-T (lipid integrated tag): An optimized tag-lipid nanoparticle design for targeted therapeutic mRNA delivery

Background: Lipid nanoparticles (LNPs) are the leading platform for mRNA delivery, but targeted delivery remains challenging. Factors such as lipid composition, particle size, charge, and ionizable lipid selection influence biodistribution, cellular uptake, and mRNA translation. Antibody-decorated LNPs offer a strategy to expand therapeutic applications. Approach: Conventional antibody decoration methods, such as post-formulation conjugation (click or maleimide chemistry), fusion proteins, or site-specific lipid conjugation, require chemical modification of antibodies. Modifications that can compromise stability and increase aggregation risk. To address this, we developed a modular system using a short peptide tag integrated into the LNP surface, enabling rapid antibody attachment via a bispecific antibody design without chemical conjugation. Innovation: Our 9-amino-acid tag (optimized in our recent Nature com. publication: PMID 39500897) binds an scFv (single-chain variable fragment) domain with picomolar affinity. The tag shows minimal immunogenicity risk in vitro and in vivo, likely as the tag is shielded upon binding. We demonstrate two complementary strategies for tag incorporation on the LNP: 1. Protein-based: Recombinant inert ApoE (ApoEi)-fusion tag for rapid coating of preformed LNPs.2. Synthetic lipid-based: DSPE-PEG-tag conjugate integrated during LNP assembly. Both approaches preserve tag accessibility and enable efficient antibody decoration. The ApoEi-tag design uniquely also blocks ApoE-LDL receptor interactions, and we can display that this reduces liver tropism. Results: Using this platform, we achieved targeted mRNA delivery and translation in Her2+, CD40+, CD3+, and CD20+ cells. The synthetic DSPE-PEG-tag supports scalable, GMP-compatible production, and the ApoEi-based method enables a rapid tool for research purposes. Our human scFv can be formatted into a classical Morrison bispecific design and expressed in CHO cells at titers >8 g/L. Conclusion: These strategies provide a versatile framework for precision-targeted mRNA delivery, supporting customizable LNP therapeutics within for example oncology and autoimmune diseases.