INSIGHTS

RNA is a fundamental tool for molecular and cellular biology research. The recent COVID-19 pandemic has proved it is also invaluable in vaccine development. However, the need for cold storage to maintain RNA integrity and the practical and economic burden associated with cold chain logistics highlight the need for new and improved preservation methods. We recently showed the use of capillary-mediated vitrification (CMV), as a tool for stabilizing temperature-sensitive enzymes. Here, we demonstrate the use of CMV as a method to preserve mRNA. The CMV process was performed by formulating a green fluorescent protein (GFP)-encoding mRNA with common excipients, applying the solution to a porous support, referred to as the scaffold, and drying the samples under vacuum for 30 min. The CMV preserved samples were stored at 55 °C for up to 100 days or 25 °C for 60 days and analyzed by electrophoresis and for transfection efficiency in a cell-based assay. The 55 °C-stressed mRNA exhibited comparable electrophoresis banding patterns and band intensity when compared to a frozen, liquid control. Additionally, the CMV stabilized mRNA maintained 97.5 ± 8.7% transfection efficiency after 77 days and 78.4 ± 3.9% after 100 days when stored 55 °C and analyzed using a cell-based assay in the CHO-K1 cell line. In contrast, a liquid control exhibited no bands on the electrophoresis gel and lost all transfection activity after being stored overnight at 55 °C. Likewise, after 60 days at 25 °C, the CMV-processed samples had full transfection activity while the activity of the liquid control was reduced to 40.1 ± 4.6%. In conclusion, CMV is a simple formulation method that significantly enhances the thermal stability of mRNA, requires minimal processing time, and could enable formulation of mRNA that can tolerate exposure to temperatures well above 25 °C during shipment and deployment in extreme environments.

Capillary-mediated vitrification (CMV) is a novel method for stabilizing biological molecules and complexes. CMV leverages capillary evaporation to enable rapid desiccation of aqueous solutions while avoiding both freezing and boiling. In the CMV process, an aqueous solution containing the biological material of interest and common excipients is applied to a solid, porous support, referred to as the scaffold, and desiccated under vacuum. The pores within the scaffold accelerate drying by increasing surface area while preventing boiling through the interaction of the vapor pressure, capillary forces, and viscous forces. The process, which can be completed in under an hour, produces an amorphous dried product with enhanced thermal stability. In this study, CMV is demonstrated using luciferase as a model system. Using a 30-minute drying time, residual moisture levels of <4% were achieved. CMV-stabilized luciferase maintained full activity when stored for up to 6 weeks at 25 °C and >70% activity after 6 weeks at temperatures up to 45 °C. The liquid formulated enzyme lost all activity after 1 day at 37 °C or 4 h at temperatures above 37 °C. The data presented in this report demonstrate that CMV is a promising alternative to traditional biopreservation methods.