Viabilities of long-term cryopreserved CHO-TRET1 cells with trehalose and DMSO

Trehalose acts as a non-toxic cryoprotectant agent (CPA) to CHO-TRET1 cells, which are CHO-K1 cells that express the trehalose transporter. This study examines the viabilities during long-term storage at 193 K of cryopreserved CHO-TRET1 cells with trehalose, and compares them to the corresponding viabilities with 10 wt%-dimethyl sulfoxide (DMSO). The cryopreserved samples are selected to have a 1-week storage viability exceeding 0.7. Results show that this high viability with trehalose is maintained at the same level for about one year of storage, and gradually decrease to about 0.55 +/- 0.16 after about 2.5 years. Comparison of this result with the corresponding case with DMSO suggests that the cryoprotective ability of trehalose is slightly weaker than that of DMSO at this temperature. We discuss the effect of recrystallization of ice, and also the biological damaging, on the viabilities. Then we concluded that the cell membrane slowly degrades at 193 K, with the rate being a little faster with trehalose than with DMSO.