Glycerol-Free Cryopreservation of Red Blood Cells Enabled by Ice-Recrystallization-Inhibiting Polymers.

Cryopreservation is fundamental in prolonging the viabilities of cells and tissues of clinical and biotechnological relevance ex vivo. Furthermore, there is an increasing need to address storage at more easily accessible temperatures in the developing world because of limited resources. Here, the cryopreservation of erythrocytes (red blood cells) with storage at -20 °C using hydroxyethyl starch (HES) and the ice recrystallization inhibitor poly(vinyl alcohol) (PVA), which is a biomimetic of naturally occurring antifreeze (glyco)proteins (AF(G)Ps), is described. This strategy eliminates the need for high concentrations of membrane penetrating solvents such as glycerol or dimethyl sulfoxide (DMSO). The addition of only 0.1-0.5 wt % PVA to the polymeric cryoprotectant, HES, significantly enhances cell recovery under conditions that promote damage due to ice recrystallization. The comparative ease with which the addition and removal of both HES and PVA can be attained is an additional attractive quality. Coupled with the benefits attained by the ice recrystallization inhibition activity of PVA, this methodology therefore offers a strategy that could aid the storage and distribution of biological materials.