Application of Saccharide Cryoprotectants in the Freezing or Lyophilization Process of Lipid Nanoparticles Encapsulating Gene Drugs for Regenerative Medicine

Lipid nanoparticles (LNPs) have emerged as highly efficient drug delivery systems in gene therapy and regenerative medicine and have demonstrated great potential in recent years. Notably, LNPs encapsulating mRNA vaccines have achieved remarkable success in combating the COVID-19 epidemic. However, LNPs encapsulating mRNA encounter issues of physical and chemical instability and need to be stored and transported under harsh conditions. Lyophilization technology, which is commonly used to increase the stability of nanomedicines, has been increasingly applied to stabilize mRNA-LNPs. Appropriate cryoprotectants, such as saccharides, glycerin, and dimethyl sulfoxide (DMSO), need to be added to mRNA-LNPs during the freezing or lyophilization process to effectively preserve the physical and chemical properties of mRNA-LNPs, ensuring their stability. Saccharides (i.e., sucrose, trehalose, and maltose) are the most widely used cryoprotectants to protect the integrity of mRNA-LNPs. This is because saccharides are relatively safe molecules compared with other chemical molecules for cells and animals. However, different saccharides have varying levels of protective effects on mRNA-LNP formulations, and the optimal saccharide concentration varies depending on the specific mRNA-LNP. This article reviews the application and mechanisms of saccharide-based cryoprotectants in the freezing or lyophilization process of LNP-delivered gene therapies and regenerative medicines, offering guidance for selecting the most appropriate saccharide-based cryoprotectants for mRNA-LNP drugs during freezing or lyophilization processes.