Exploring the potential of biocompatible osmoprotectants as high efficient cryoprotectants.

Cryoprotectants (CPAs) are critical to successful cryopreservation because they can protect cells from cryoinjuries. Due to the limitations of current CPAs, especially the toxicity, the search for new effective CPAs is attracting increasing attentions. In this work, we reported that natural biocompatible osmoprotectants, which could protect cells from osmotic injury in various biological systems, might also be ideal candidates for CPAs. Three representative biocompatible osmoprotectants (proline, glycine and taurine) were tested and compared. It was found that besides presenting different ability to prevent osmotic injury, these biocompatible osmoprotectants also possessed different ability to inhibit ice formation and thus mitigated intracellular/extracellular ice injury. Due to the strongest ability to prevent the two types of injuries, we found proline performed the best in cryopreserving five different types of cells. Moreover, the natural osmoprotectants are intrinsically biocompatible to the cells, superior to the current state-of-the-art CPA-dimethyl sulfoxide (DMSO) which is a toxic organic solvent. This work opens a new window of opportunity for DMSO-free cryopreservation, and sheds light on the applications of osmoprotectants in cryoprotection, which may revolutionize the current cryopreservation technologies.