Stem cell preservation with novel cryoprotectants

Cryopreservation allows the long-term storage of biological samples by cooling them down to very low temperatures. However, to prevent freezing damage, so-called cryoprotective agents (CPAs) must be included. To date, most cryopreservation protocols rely on either dimethylsulfoxide (DMSO) or glycerol, which are ineffective for many cell types. In particular, stem cell preservation is vital for clinical applications but has poor outcomes with current protocols. This study screened seven potential CPAs, broadly based on deep eutectic solvents (DESs), for toxicity and permeability using standard cell lines (THP-1 and HaCat), and then tested them with human mesenchymal stem cells (MSCs). Recovery with new cryoprotectants based on mixtures of proline with either glycerol or ethylene glycol, or of alanine with glycerol was equal to or greater than that achieved using the current gold standard. This provides a new method of preserving stem cells that may not only lead to better cell numbers but also use CPAs that are less toxic than those currently used, which will ultimately result in better clinical outcomes. This article is part of the discussion meeting issue 'Ionic liquids and the future of soft materials'.