Figure 2.

Percentage of cell viability measured after thawing of CD34⁺ cells previously frozen with different cryoprotectants at short (20 days) and long (3 months) durations of cryopreservation. CD34⁺ were frozen with: 10% Me₂SO + 90% FBS; 1M trehalose; 1M trehalose + 10% Me₂SO, 1M trehalose + 100 µg/ml catalase; 1 M trehalose + 100 µg/ml catalase + 10% Me₂SO. The viability after thawing was evaluated by trypan blue dye exclusion assay. Data were analyzed using Student's t-test and are expressed as the mean ± standard deviation of five separate experiments. *P<0.05. Cell viability (%) = number of recovered cells after thawing ×100/number of non-cryopreserved cells (NT, 100% viability). Me₂SO, dimethyl sulfate; FBS, fetal bovine serum.