A biocompatible cell cryoprotectant based on sulfoxide-containing amino acids: mechanism and application

Abstract

The preservation of cells at cryogenic temperatures requires the presence of cryoprotectants (CPAs). Dimethyl sulfoxide (DMSO), as a state-of-the-art CPA, is widely used for the storage of many types of cells. However, its intrinsic toxicity is still an obstacle for its applications in clinical practice. Herein, we report a DMSO analogue, L-methionine sulfoxide (Met(O)–OH), as a CPA for cell cryopreservation. The molecular-level cryopreservation roles of Met(O)–OH were investigated by experiments and molecular dynamics simulations. The results also found that Met(O)–OH showed high ice recrystallization inhibition (IRI) activity and the ice crystals in Met(O)–OH solution tend to be relatively round and smooth; moreover, the ice size was significantly reduced to 30.26 μm compared with pure water (135.87 μm) or DMSO solution (45.08 μm). At the molecular level, Met(O)–OH could stably bind the surface of the ice crystals and form more stable hydrogen bonds with ice compared with L-methionine. Moreover, Met(O)–OH could significantly reduce the damage to cells caused by osmotic shock and did not change the cell viability even at high concentration (4%). Based on these results, nucleated L929 cells and anuclear sheep red blood cells (SRBCs) were used as cell models to investigate the cryopreservation activity of Met(O)–OH. The results suggested that, under the optimum protocol, Met(O)–OH showed an effective post-thaw survival efficiency with ultrarapid freezing, and the post-thaw survival efficiency of L929 cells reached 84.0%. This work opens up the possibility for an alternative to traditional toxic CPA DMSO, and provides insights for the development of DMSO analogues with non-toxic/low toxicity for cell cryoprotection applications.