Storage conditions play a critical role in the performance of mRNA-based therapies, including those used in COVID-19 vaccines. A recent study conducted by researchers at The University of Texas at Austin in collaboration with Eli Lilly and Company has revealed that freezing can compromise the integrity of mRNA lipid nanoparticles (LNPs)—the delivery vehicles that carry genetic material into human cells.
What Happened: Freezing Damages mRNA Nanoparticles
The study found that when mRNA LNPs are subjected to freezing, the lipid layers that encapsulate the mRNA begin to degrade. This degradation disrupts the structure of the nanoparticles, reducing their ability to deliver the mRNA payload effectively to target cells. The researchers observed a significant drop in functional performance after repeated freeze-thaw cycles, indicating that freezing may not be ideal for long-term storage of these therapeutics.
However, the team discovered that adding a specific buffer—tris (tris(hydroxymethyl)aminomethane)—to the nanoparticle formulation can mitigate this damage. Tris buffer helps stabilize the lipid structure during freezing, preserving the nanoparticles’ ability to deliver mRNA without significant loss of potency. This finding suggests a practical solution for improving the shelf life and reliability of mRNA-based treatments under real-world storage conditions.
Key Facts from the Research
- Freezing causes structural degradation of mRNA lipid nanoparticles (LNPs), reducing their delivery efficiency.
- Repeated freeze-thaw cycles exacerbate the instability of LNPs.
- Adding tris buffer to the LNP formulation significantly improves stability during freezing.
- The study was conducted in collaboration between The University of Texas at Austin and Eli Lilly and Company.
- Results are based on in vitro experiments and do not yet include clinical trials or human data.
Background: How mRNA Lipid Nanoparticles Work
MRNA lipid nanoparticles (LNPs) are a delivery system used to transport synthetic mRNA into human cells. The mRNA carries instructions for cells to produce specific proteins, such as those that trigger immune responses or help treat genetic disorders.
LNPs consist of a lipid layer that surrounds the mRNA, protecting it from degradation and enabling it to enter cells. The lipids are typically composed of ionizable lipids, phospholipids, cholesterol, and PEGylated lipids. These components work together to form a stable, biocompatible structure that can be administered via injection.
While LNPs have been successfully used in vaccines like those developed by Pfizer-BioNTech and Moderna, their long-term stability under various storage conditions—especially temperature extremes—has remained a key challenge. This research addresses one of the most pressing concerns: how to maintain potency during storage without relying on ultra-cold chain logistics.
Why It Matters: Stability Improves Accessibility and Scalability
For mRNA therapies to reach a broader global population, they must be stable under a range of storage conditions. Current storage requirements for many mRNA vaccines—such as maintaining temperatures below -20°C or -70°C—require specialized, expensive infrastructure, especially in low-resource settings.
If freezing can be reduced or eliminated through formulation improvements, such as the use of tris buffer, then these treatments could be stored at more accessible temperatures. This would lower logistical costs and expand access to rural or underserved communities, particularly in developing nations where cold chain infrastructure is limited.
Moreover, enhanced stability could allow for longer shelf lives, reducing the need for frequent reprocessing and enabling more flexible distribution networks. This is especially important for treatments targeting rare diseases or those requiring frequent dosing.
Limitations and Open Questions
While the results are promising, the study has several limitations that must be addressed before widespread application.
First, the research was conducted in laboratory settings using synthetic mRNA and in vitro models. Real-world performance in human cells or in vivo environments has not yet been tested. The impact of tris buffer on immune responses or long-term safety remains unknown.
Second, the study focused on a specific type of LNP formulation. It is unclear whether the findings apply to all mRNA-based therapies, including those for cancer or genetic disorders, which may use different lipid compositions.
Third, the optimal concentration and pH of tris buffer have not been fully optimized. Further research is needed to determine the ideal formulation for different mRNA payloads and delivery goals.
Finally, no data has been published on the long-term stability of LNPs with tris buffer under repeated freeze-thaw cycles or over extended storage periods. These parameters are essential for regulatory approval and commercial deployment.
What to Watch Next
Researchers and pharmaceutical companies are likely to conduct follow-up studies to validate these findings in more complex biological systems. Key areas of future investigation include:
- Testing tris-buffered LNPs in animal models to assess biological efficacy and safety.
- Exploring whether similar stabilization strategies can be applied to other types of nucleic acid delivery systems, such as DNA or siRNA.
- Investigating the impact of tris buffer on immunogenicity and potential off-target effects.
- Collaborating with regulatory bodies to assess whether these formulation changes meet current standards for vaccine stability and potency.
Additionally, this research may inspire new approaches to stabilizing other biologic therapies that rely on sensitive delivery systems. For instance, similar principles could be applied to protein-based or antibody-based treatments.
For readers interested in the intersection of nanotechnology and medicine, a related development is the laser-based test that detects colorectal cancer biomarkers in blood, which demonstrates how advanced diagnostics are being developed to support precision medicine. Meanwhile, another study on silver nanoparticle layers enhancing CO₂-to-CO conversion highlights how nanomaterials are being optimized for environmental applications.
As mRNA technology continues to evolve, understanding the physical and chemical stability of its delivery systems will remain a cornerstone of innovation. This research provides a clear pathway toward more robust, accessible, and scalable mRNA-based therapies.
Sources & further reading
Featured image: The Flight Research Building at the National Advisory Committee for Aeronautics (NACA) Aircraft Engine Research Laboratory is a 272- by 150-foot hangar with an internal height up to 90 feet. The hangar’s massive 37.5-foot-tall and 250-foot-long doors can be opened in sections to suit different size aircraft. The hangar has sheltered a diverse fleet of aircraft over the decades. These have ranged from World War II bombers to Cessna trainers and from supersonic fighter jets to a DC–9 airliner. At the time of this September 1942 photograph, however, the hangar was being used as an office building during the construction of the laboratory. In December of 1941, the Flight Research Building became the lab’s first functional building. Temporary offices were built inside the structure to house the staff while the other buildings were completed. The hangar offices were used for an entire year before being removed in early 1943. It was only then that the laboratory acquired its first aircraft, pilots and flight mechanics. The temporary one-story offices can be seen in this photograph inside the large sliding doors. Also note the vertical lift gate below the NACA logo. The gate was installed so that the tails of larger aircraft could pass into the hangar. The white Farm House that served as the Administration Building during construction can be seen in the distance to the left of the hangar. by NASA Glenn Research Center, Public domain, via Wikimedia Commons. Image source