A multistep platform identifies spleen-tropic lipid nanoparticles for in vivo T cell-targeted delivery of gene-editing proteins.

Lipid nanoparticles (LNPs) are a promising nonviral delivery system for gene-editing proteins, but optimal formulations remain underexplored. Unlike messenger RNA-based approaches, ribonucleoprotein delivery enables immediate genome editing without relying on endogenous translation. However, intracellular delivery remains a major challenge due to protein size, charge variability, and susceptibility to denaturation and degradation. Here, we present a multistep screening platform to optimize LNP formulations for gene-editing protein delivery, focusing on in vivo T cell targeting. Through in vitro screening of a composition library, we identified top-performing candidates. In vivo screening in Ai9 mice revealed a spleen-tropic LNP formulation that preferentially targets T cells, enabling efficient gene editing in vivo. Using this LNP formulation, we achieved targeted knockout of CCR5 and PD-1 in splenic T cells, supporting potential applications in HIV resistance and cancer immunotherapy. Furthermore, a machine learning-guided mechanistic study revealed key design principles for LNP-based protein delivery, highlighting unexplored opportunities for in vivo genome-editing therapies.