Exploring novel cell cryoprotectants based on neutral amino acids

Cryoprotectants play a key role in cell cryopreservation because they can reduce cryoinjuries to cells associated with ice formation. To meet the clinical requirements of cryopreserved cells, cryoprotectants should be biocompatible, highly efficient and easily removable from cryopreserved cells. However, integration of these properties into one cryoprotectant still remains challenging. Herein, three biocompatible neutral amino acids, including β-alanine, γ-aminobutyric acid and ε-aminocaproic acid, are first reported to have the potential as such ideal cryoprotectants. The results demonstrate that they can inhibit ice formation and reduce osmotic stress to provide extracellular and intracellular protection, thereby ensuring high cryopreservation efficiency for both anuclear and nucleated cells. More importantly, due to the remarkable osmotic regulation ability, the neutral amino acids can be rapidly removed from cryopreserved cells via a one-step method without causing observable damage to cells, superior to the current state-of-the-art cryoprotectants—dimethyl sulfoxide and glycerol. This work provides a new perspective to develop novel cryoprotectants, which may have dramatic impacts on solvent-free cryopreservation technology to support the cell-based applications, such as cell therapy and tissue engineering, etc.