mRNA Encapsulation and Delivery via MOF Nanostructures: First In Vivo Evidence

Study Background and Research Question

Messenger RNA (mRNA) therapeutics have rapidly advanced in recent years, with the clinical success of mRNA vaccines highlighting both the potential and the challenges of nucleic acid delivery. While lipid nanoparticles (LNPs) have been the dominant vector for mRNA transport, their limitations—such as cold chain requirements and the risk of innate immune activation—have prompted the exploration of alternative, non-viral carriers. Metal-organic frameworks (MOFs) have attracted attention for their high tunability and stability, but until now, their use in mRNA delivery remained largely unexplored. The central question addressed by Lawson et al. (2025) is whether MOF nanostructures, specifically zeolitic imidazole framework-8 (ZIF-8), can encapsulate, stabilize, and deliver functional mRNA to mammalian cells and animal models, and how this strategy compares to established delivery systems (DOI: 10.1002/adfm.202504465).

Key Innovation from the Reference Study

The pivotal innovation of this work is the development of a hybrid polymer-MOF particle capable of protecting and delivering mRNA in biological environments. The formulation leverages a polyethyleneimine (PEI) core surrounded by a ZIF-8 shell, forming a robust structure that mitigates the rapid loss of mRNA in aqueous and biological media—a common drawback of non-modified MOF encapsulation. This is the first demonstration of mRNA encapsulation in MOFs leading to productive in vitro and in vivo protein expression, and it uniquely showcases the ability to store functional mRNA at room temperature for extended periods, broadening the practical scope of mRNA-based therapeutics (paper).

Methods and Experimental Design Insights

Lawson et al. designed a systematic approach to optimize mRNA encapsulation, stabilization, and release:

• mRNA Encapsulation: Initial attempts to load mRNA directly into ZIF-8 produced high encapsulation efficiency but suffered rapid mRNA loss in biological media, likely due to competitive ion exchange and MOF instability.
• Polymer Enhancement: Incorporation of PEI formed a polyplex with mRNA, which was then encapsulated within the ZIF-8 shell. This dual structure preserved mRNA integrity and reduced premature release.
• In Vitro and In Vivo Validation: The team tested delivery in multiple cell lines and in mouse models, tracking protein expression (via luciferase reporter) as an indicator of successful mRNA translation.
• Storage Stability: Functional assays following storage at room temperature for up to three months (in vitro) and one month (in vivo) assessed the preservation of mRNA activity over time.

The use of luciferase mRNA as a quantitative reporter enabled precise assessment of translation efficiency, mirroring approaches seen in modern translation efficiency assays and in vivo bioluminescence imaging workflows (paper).

Protocol Parameters

• mRNA encapsulation yield | ~90% (w/w) | In vitro MOF-mRNA loading | High yield supports therapeutic dosing | paper
• Polymer:mRNA mass ratio | 5:1 | Core-shell complex formation | Ensures stable PEI-mRNA complex for ZIF-8 coating | paper
• ZIF-8 shell thickness | ~50 nm | Particle engineering | Provides protection without impeding release | paper
• Room temperature storage | 1-3 months | mRNA activity retention | Preserves functional output post-storage | paper
• Reporter assay: firefly luciferase | Relative light units (RLU) | Translation efficiency quantification | Bioluminescence indicates mRNA delivery | paper
• Fluorescently labeled mRNA (e.g., Cy5) | workflow_recommendation | Real-time tracking of uptake | Enables dual-mode imaging (fluorescence + luminescence) | workflow_recommendation
• Cap1-capped, 5-moUTP-modified mRNA | workflow_recommendation | Increased translation, reduced immunity | Enhances compatibility with mammalian expression | workflow_recommendation

Core Findings and Why They Matter

The study's findings redefine the landscape of mRNA delivery vectors:

• Stabilization: PEI-ZIF-8 hybrid particles maintained mRNA stability in biological fluids, overcoming a major obstacle of MOF-only carriers.
• Efficient Gene Expression: Delivered mRNA yielded robust protein expression in multiple cell lines and in murine models, with performance comparable to commercial LNP-based reagents (paper).
• Long-Term Storage: Notably, functional luciferase expression was detected after storing the mRNA-MOF complexes at room temperature for up to three months in vitro and one month in vivo, demonstrating a path toward cold chain-independent distribution (paper).
• Low Immunogenicity: The polymer-MOF design mitigates innate immune activation, a critical consideration for therapeutic applications.

These results have direct implications for both translational research—where robust, dual-mode detection (bioluminescence and fluorescence) is needed—and for the practical deployment of mRNA vaccines or gene therapies in resource-limited settings.

Comparison with Existing Internal Articles

Internal resources on EZ Cap™ Cy5 Firefly Luciferase mRNA (5-moUTP) and related products describe the value of dual-mode detection, Cap1 capping, and 5-moUTP modifications for improving mRNA translation and minimizing innate immunity. These features align well with the requirements for effective use in MOF-based delivery systems:

• The internal article "EZ Cap™ Cy5 Firefly Luciferase mRNA (5-moUTP): Dual-Mode ..." emphasizes robust, low-immunogenicity mammalian expression, which is congruent with the goals of the Lawson et al. study (internal).
• "EZ Cap™ Cy5 Firefly Luciferase mRNA (5-moUTP): Fluorescen..." highlights dual-mode detection and reduced immune activation, supporting translation efficiency assays and immune suppression studies—both critical for evaluating MOF-mRNA constructs (internal).
• These internal sources also discuss workflow compatibility with fluorescence microscopy and flow cytometry, aligning with the reference study's emphasis on real-time mRNA tracking and bioluminescence imaging.

While internal articles focus on reagent performance in standard transfection and imaging workflows, the Lawson et al. study advances applicability to MOF-based encapsulation, thereby extending the utility of high-performance mRNAs for next-generation delivery platforms.

Limitations and Transferability

Despite these advances, several limitations remain. The MOF polymer shell design, while effective in murine models, requires further validation in human tissues and disease-relevant settings. Potential cytotoxicity from PEI, issues of scalability, and the need for rigorous batch-to-batch consistency must be addressed before clinical translation. Additionally, the interplay between MOF chemistry and mRNA modifications (e.g., 5-moUTP incorporation) warrants further study to maximize translation efficiency and minimize unwanted immune activation (paper). Transferability to other mRNA cargos or larger-scale manufacturing will depend on the tunability of the MOF shell and compatibility with various capping and labeling chemistries.

Why this cross-domain matters, maturity, and limitations

The application of MOFs, traditionally used in materials science, to mRNA delivery creates a bridge between nanomaterials engineering and gene therapy. This cross-domain innovation is still in its early experimental phase; while in vivo murine data are promising, further studies are needed to establish safety, efficacy, and regulatory pathways for clinical use (paper).

Research Support Resources

To facilitate translation efficiency assays, mRNA delivery studies, and dual-mode imaging in MOF-based or other advanced delivery systems, researchers may utilize EZ Cap™ Cy5 Firefly Luciferase mRNA (5-moUTP) (SKU R1010). This Cap1-capped, 5-moUTP- and Cy5-modified mRNA from APExBIO enables both sensitive bioluminescence and fluorescence-based tracking, supporting studies in line with the protocols and detection strategies described by Lawson et al. (2025) (paper). For additional workflow recommendations and application notes, see internal resource summaries above.