Impact of Lyoprotectants on Product Stability of Freeze-Dried mRNA-Lipid Nanoparticles

The mRNA lipid nanoparticle (LNP) vaccines for COVID-19 have been an outstanding achievement in combatting the global pandemic. However, these vaccines need to be stored at ultra-low temperatures to maintain their stability and efficacy. Such low temperatures impose significant burdens on storage, transportation, distribution, and clinical use. Developing a lyophilized formulation could be a potential solution to enhance the stability of mRNA-LNP formulations at higher temperatures. Lyoprotectants are typically incorporated into the lyophilization formulation to protect biologics from freezing and dehydration stresses and to support their long-term storage.
Various lyoprotectant compositions have been investigated in our study, including sucrose, trehalose, and other compounds with higher glass transition temperatures. A higher glass transition temperature can be beneficial for storage stability. Particle size distribution, encapsulation efficiency, residual moisture, and in vitro transfection efficiency of mRNA-LNPs after lyophilization and storage were assessed, compared with the mRNA-LNPs stored in liquid and frozen forms. mRNA-LNPs freeze-dried with specific formulations demonstrated the ability to maintain particle size and encapsulation efficiency, while also achieving low residual moisture and high transfection efficiency. Interestingly it was found that some lyoprotectants were able to maintain the particle sizes and encapsulation efficiency, while the transfection efficiency was reduced. Full evaluations of the freeze-dried mRNA-LNPs including efficacy test are needed.