Nie, Liu, Song, and Yao et al. developed a spleen delivery platform of mRNA-loaded lipid nanoparticles (LNPs) covalently bound to erythrocytes (mRNA-LNP-Ery), which naturally target splenic CD11b+ myeloid cells. Unlike conventional LNPs, mRNA-LNP-Ery entered cells via phagocytosis, avoiding lysosomal degradation and efficiently delivering mRNA. CAR myeloid cells (HER2 or CD19) adopted a proinflammatory antigen-presenting phenotype, migrated to tumors, and stimulated T and NK cell influx, potent antitumor activity, and systemic immunity, which was spleen-dependent. Repeated doses of mRNA-LNP-Ery resulted in superior efficacy at 1/10 the dose of LNPs.
Contributed by Katherine Turner
ABSTRACT: Engineering myeloid cells with chimeric antigen receptors (CARs) holds great therapeutic promise, but their generation in vivo remains challenging. Here, we developed an erythrocyte-mediated messenger RNA (mRNA) delivery platform, termed mRNA-LNP-Ery, in which mRNA-loaded lipid nanoparticles (LNPs) are covalently anchored onto erythrocytes. Exploiting erythrocytes' intrinsic splenic homing capacity and unique biocompatibility, mRNA-LNP-Ery enables highly selective and efficient mRNA delivery to CD11b(+) myeloid cells in the spleen, with minimal uptake by hepatocytes. We also demonstrated that mRNA-LNP-Ery is internalized through phagocytosis and avoids lysosomal degradation, resulting in enhanced cytosolic mRNA translation. Delivery of mRNAs encoding CARs targeting human epidermal growth factor receptor 2 (HER2) or CD19 generated functional CAR myeloid cells in vivo that adopted a proinflammatory, antigen-presenting phenotype. These cells migrated to tumors, eliminated cancer cells, and remodeled the tumor microenvironment, leading to increased infiltration of effector T and natural killer (NK) cells. The antitumor effect was abolished in splenectomized mice and partially diminished in nude mice, indicating that therapeutic activity depends on both CAR myeloid cell formation within the spleen and their cross-talk with adaptive immunity. Furthermore, repeated administration of mRNA-LNP-Ery achieved superior antitumor efficacy to conventional mRNA-LNPs at one-tenth the mRNA dose, with minimal systemic toxicity, underscoring the high efficiency and safety of spleen-targeted delivery. Together, our findings established a clinically translatable erythrocyte-based mRNA platform that enables direct in vivo immune cell programming and advances CAR myeloid therapies for solid tumors.
Author Info: (1) Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China. Westlake La
Author Info: (1) Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China. Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China. (2) Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China. Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China. Research Center for Industries of the Future and School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China. (3) Westlake Therapeutics, Hangzhou, Zhejiang 310024, China. (4) Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China. Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China. (5) Westlake Therapeutics, Hangzhou, Zhejiang 310024, China. (6) Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China. Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, School of Life Sciences, Peking University, Beijing 100871, China. (7) Key Laboratory of Growth Regulation and Translational Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China. Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China. Research Center for Industries of the Future and School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310030, China.
