A preparation method for mRNA-LNPs with improved properties

The properties of mRNA lipid nanoparticles (mRNA-LNPs), including size, empty particles, morphology, storage stability, and transfection potency, are critically dependent on the preparation methods. Here, a Two-step tangential-flow filtration (TFF) method was successfully employed to improve the properties of mRNA-LNPs during the preparation process. This method involves an additional ethanol removal step prior to the particle fusion process. Notably, this innovative approach has yielded mRNA-LNPs with larger particles, a reduced proportion of empty LNPs, optimized storage stability (at least 6 months at 2-8 °C), improved in vitro transfection efficiency, and minimized distribution in the heart and blood in vivo. In summary, this study represents the implementation of the innovative Two-step TFF method in the preparation of mRNA-LNPs. Our findings indicate substantial enhancements in the properties of our mRNA-LNPs, specifically with regard to the percentage of empty LNPs, stability, transfection efficiency, and in vivo distribution. These improvements have the potential to optimize their industrial applicability and expand their clinical use.