Lipid nanoparticles (LNPs) hold promise for therapy, but non-specific liver accumulation hinders their clinical translation for in vivo CAR development. Furthermore, delivering mRNA to primary Natural Killer (NK) cells without altering their intrinsic immune functionalities or causing cytotoxicity remains a major challenge. To overcome these hurdles, we developed a novel LNP platform optimized for safe, efficient mRNA delivery to refractory immune cells for both ex vivo and in vivo applications.
We engineered a novel ionizable and helper lipid library and screened it using primary human NK cells, which are inherently refractory to genetic engineering and mRNA delivery. The optimal LNP formulations achieved high transfection efficiency without compromising cell viability or altering metabolic activity. These LNPs successfully generated ex vivo CAR-NK cells with high anti-MSLN CAR expression, driving robust antitumor activity against pancreatic ductal adenocarcinoma (PDAC) cell lines. Importantly, systemic in vivo evaluation demonstrated an excellent safety profile with spleen-selective biodistribution, effectively bypassing hepatic accumulation.
This novel LNP platform enables safe mRNA delivery without compromising immune cell functions, validated via diverse assays for ex vivo CAR immunotherapy. Leveraging its exceptional spleen-targeting activity and safety profile, this platform demonstrates immense potential as a robust vehicle for in vivo CAR immunotherapy, with further validation planned in a syngeneic lymphoma mouse model.