Optimization of Lipid Nanoparticles with Robust Efficiency for the Delivery of Protein Therapeutics to Augment Cancer Immunotherapy

Lipid nanoparticles (LNPs) have been successful in delivering nucleic acids like siRNA and mRNA, but face challenges in protein delivery due to limited protein encapsulation and endosome escape. In this study, a family of LNPs is developed with robust high efficiency in addressing the multiple barriers in cytosolic protein delivery by incorporating clinically approved ionizable lipids into traditional cationic LNPs. The combination of cationic and ionizable lipids enables efficient protein binding and endosomal escape. Optimized LNPs efficiently deliver various proteins, including antibodies, enzymes, toxins, and Cas9 into living cells with reserved functions. Moreover, the designed LNPs show high serum stability during protein delivery, and the serum albumin adsorbed on LNPs facilitates protein delivery via albumin receptor-mediated endocytosis, enabling highly efficient protein delivery in vivo. The optimized LNPs successfully deliver therapeutic proteins such as saporin and interleukin-10 (IL-10) to inhibit tumor growth in several animal models. The IL-10 loaded LNPs enhanced the proliferation and cytotoxicity of T cells and improved the antitumor effect of adoptive transferred OT-1 CD8⁺ T cells to melanoma. This study expands the applications of LNPs for the delivery of biomacromolecules, and the developed LNP formulations have enormous potential for the delivery of protein therapeutics to treat various diseases.