Vitrification tendency and stability of DP6-based vitrification solutions for complex tissue cryopreservation

Vitrification tendency and stability of the amorphous state were analyzed by means of differential scanning calorimetry (DSC) for the vitrification solution DP6, with and without additional solutes to enhance ice suppression. This study is a part of an ongoing research effort to characterize the thermophysical and mechanical properties of DP6 and its derivatives, and their qualities as cryoprotective solutions. DP6 was determined to have a critical cooling rate necessary to ensure vitrification of 2.7 °C/min. The following additional solutions were tested: DP6 + 6% (2R, 3R) 2,3-butanediol, DP6 + 6% 1,3-cyclohexanediol, DP6 + 6% (0.175M) sucrose, DP6 + 12% PEG 400, and DP6 + 17.1% (0.5 M) sucrose. The additives decreased the critical cooling rate of the DP6 solution to rates below 1 °C/min that were not quantifiable by the DSC techniques used. The following critical warming rates necessary to avoid devitrification were identified for DP6 and the modified solutions, respectively: 189 °C/min, 5 °C/min, ≈ 1 °C/min, 15 °C/min, <1 °C/min, and <1 °C/min. Glass transition temperatures and melting temperatures were also measured. Sucrose was the least effective additive on a per mass basis, with 1,3-cyclohexanediol appearing to be the most effective additive for suppressing ice formation in DP6.