Lingling Tao, Zhe Zhai, Nan-Yu Chen, Yong-Xian Cheng, Xu-Han Liu
Background/Objectives: As a primary mRNA delivery platform, lipid nanoparticles (LNPs) often induce oxidative stress that compromises mRNA translation efficiency. Natural polysaccharides are known for their antioxidant properties. Methods: To lower LNP toxicity and boost mRNA delivery, we conducted a preliminary pro-proliferation screen of 34 natural polysaccharides using a CCK-8 cytotoxicity assay in murine macrophage RAW264.7 cells, serving as an initial filter for bioactivity. Subsequently, their ability to improve LNP-mediated transfection efficiency was validated in HEK293T cells—a standard model for quantifying protein expression. After that, Ganoderma lucidum polysaccharide (GLP) was selected as a lead candidate for potential adjuvant. Results: Formulated into mRNA-LNPs by first preparing the LNPs via a one-step nano-precipitation process, followed by direct incorporation of GLP through mixing, the resulting GLP-LNP formulation significantly alleviated intracellular oxidative stress by elevating glutathione and superoxide dismutase while reducing malondialdehyde, indicating restored redox homeostasis. This modulation correlated with markedly enhanced transfection efficiency, achieving significantly higher protein expression both in vitro (3.2-fold) and in vivo (2.1-fold) compared to LNP alone. Mechanism studies implicated the activation of the nuclear factor erythroid 2-Related Factor 2 (Nrf2) pathway in this protective effect. Conclusions: We conclude that GLP represents a novel adjuvant paradigm that concurrently enhances mRNA transfection and mitigates oxidative toxicity, demonstrating significant potential for advanced vaccinology.