Ganoderma lucidum Polysaccharide: A Novel Adjuvant for mRNA-LNP Delivery

Study Background and Research Question

Messenger RNA (mRNA) therapeutics, especially vaccines, have rapidly transformed biomedical research and translational medicine due to their flexible design, rapid production, and antigenic precision. However, the clinical promise of mRNA is still constrained by its inherent instability, susceptibility to enzymatic degradation, and strong innate immunogenicity. Lipid nanoparticles (LNPs) have emerged as the main non-viral carriers to protect and deliver mRNA payloads, but these systems are not without drawbacks. Chief among them is the induction of intracellular oxidative stress, leading to the generation of reactive oxygen species (ROS) that impede mRNA translation and compromise cell health. The reference study by Tao et al. (Pharmaceutics 2026, 18, 259) addresses a timely and consequential research question: Can natural antioxidant polysaccharides, specifically from Ganoderma lucidum, be leveraged to mitigate LNP-induced oxidative toxicity and thereby enhance mRNA delivery and protein expression?

Key Innovation from the Reference Study

The study introduces a dual-function strategy: using Ganoderma lucidum polysaccharide (GLP) as a natural adjuvant co-formulated with mRNA-LNPs to simultaneously suppress oxidative stress and boost transfection efficiency. Unlike previous approaches that focus on modifying the LNP carrier itself (e.g., biodegradable ionizable lipids, PEG alternatives), the GLP approach offers a modular, bioactive additive that intervenes at the interface of redox biology and innate immune modulation. This represents a conceptual advance by bridging antioxidant adjuvant design with nucleic acid delivery technology, aiming to enhance the efficacy and safety of mRNA-based therapeutics.

Methods and Experimental Design Insights

The authors began with a high-throughput screening of 34 natural polysaccharides to identify candidates with pro-proliferative and cytoprotective properties, using a CCK-8 viability assay in RAW264.7 murine macrophages. GLP emerged as a top performer and was then evaluated for its ability to enhance LNP-mediated mRNA delivery in HEK293T cells, a widely used model for protein expression analysis. LNPs were prepared by a one-step nanoprecipitation method, then GLP was directly incorporated by mixing, yielding GLP-LNP complexes.

The authors deployed a combination of biochemical assays to measure markers of oxidative stress: intracellular glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA). Protein expression following mRNA-LNP or GLP-LNP transfection was quantified in vitro and in vivo using established luciferase reporter systems, while mechanistic studies interrogated activation of the Nrf2 (nuclear factor erythroid 2–related factor 2) antioxidant pathway.

Core Findings and Why They Matter

GLP co-formulation led to several notable outcomes:

• Oxidative Stress Mitigation: GLP-LNPs elevated GSH and SOD levels while reducing MDA, indicating restored redox balance in recipient cells.
• Enhanced Transfection Efficiency: In vitro, GLP-LNPs achieved a 3.2-fold increase in protein expression compared to LNPs alone; in vivo, the increase was 2.1-fold (see reference).
• Nrf2 Pathway Activation: Mechanistic assays implicated Nrf2 as a mediator of GLP’s protective effect, linking antioxidant response with improved mRNA translation.

These findings are significant on multiple fronts. First, they demonstrate that oxidative stress is a major bottleneck for mRNA-LNP efficacy, and that modulating cellular redox status is a viable strategy to overcome this limitation. Second, the approach does not require complex chemical modifications to the LNP or mRNA, potentially simplifying regulatory and manufacturing processes. Lastly, the duality of GLP—as both a bioprotectant and an immunomodulator—positions it as a promising adjuvant for next-generation mRNA vaccines and gene therapies.

Comparison with Existing Internal Articles

Several internal resources contextualize and extend the findings of this study. For example, the article "Lipid Nanoparticle Delivery of SOD2 mRNA Mitigates Renal IRI" underscores the importance of antioxidant strategies in mRNA-LNP delivery. In that model, SOD2 mRNA delivered via LNPs reduced mitochondrial oxidative stress in renal injury, lending further support to the concept that redox modulation enhances the therapeutic window of mRNA nanocarriers.

From an assay optimization perspective, "Reliable Assays with EZ Cap™ Firefly Luciferase mRNA with Cap 1 structure" details how the use of capped, polyadenylated mRNA (such as EZ Cap™ Firefly Luciferase mRNA) improves transcription efficiency and reproducibility in reporter assays. This complements the reference study's focus on maximizing translation and signal output, suggesting that both delivery vehicle refinement and transcript engineering are synergistic for high-fidelity gene regulation reporter assays.

Finally, the strategic overview in "Cap 1-Driven Revolution: Strategic Guidance for Translational Assays" highlights the translational impact of Cap 1-capped mRNA in molecular biology, reinforcing the importance of both advanced delivery systems and optimized mRNA constructs for robust bioluminescent reporter applications.

Limitations and Transferability

While the results are promising, several limitations warrant caution. The study's primary models were murine macrophages and HEK293T cells, and the in vivo validation, while supportive, was preliminary. The molecular mechanisms underlying GLP's adjuvant effect, though linked to Nrf2 activation, may involve additional pathways not fully delineated in this work. Furthermore, the specificity of GLP’s effect relative to other polysaccharides or adjuvants remains to be established, and long-term safety data in higher organisms are lacking.

Transferability to clinical mRNA vaccine platforms will require demonstration that GLP does not interfere with antigen presentation or adaptive immune priming, and that its redox-modulatory actions are consistent across diverse tissues and delivery contexts. Nonetheless, the concept of pairing antioxidant adjuvants with mRNA-LNP delivery is now empirically validated and offers a compelling avenue for further research.

Protocol Parameters

• Polysaccharide screening: Perform initial viability assays (e.g., CCK-8) in target cell lines to identify bioactive candidates prior to LNP formulation.
• LNP preparation: Use a one-step nanoprecipitation method for forming LNPs; incorporate GLP by direct mixing into the nanoparticle suspension prior to mRNA loading.
• Transfection efficiency quantification: Employ luciferase reporter assays in vitro and in vivo to assess protein expression post-delivery.
• Oxidative stress assessment: Measure GSH, SOD, and MDA levels in transfected cells to evaluate redox status after treatment.
• Mechanistic validation: Use Nrf2 pathway inhibitors/activators or knockout models to confirm pathway involvement where feasible.

Research Support Resources

To facilitate similar mRNA delivery and translation efficiency assays, researchers can utilize EZ Cap™ Firefly Luciferase mRNA (SKU R1018), which features a Cap 1 structure and an optimized poly(A) tail for robust and sustained luciferase expression. This reagent is suitable as a sensitive bioluminescent reporter for molecular biology, enabling the quantitative evaluation of mRNA-LNP performance, antioxidant adjuvant effects, and gene regulation workflows. For best results, follow recommended protocols for mRNA handling and transfection as described in the product specification. APExBIO’s solution is compatible with both in vitro cell-based and in vivo bioluminescence imaging applications, supporting advanced research in mRNA delivery and functional genomics.