Figure 5.

Cryopreservation of human dermal fibroblast (HDF) and human umbilical cord blood stem cells (UCBSCs). A) Cell viability after various exposure times to CPA solution at 4 °C. B) Yield of printing and laser warming. C) Post cryopreservation viability using different GNR concentrations and laser energies in 4 µL droplets. D) Experimental post cryopreservation viability using various droplet sizes and different warming methods. Simulated viability was calculated by the volume percentage of the droplet that has warming rate higher than 2.5 × 10⁵ °C min⁻¹. E) Viability of control and various treatment groups including CPA loading and unloading, laser warming, and convective warming. F) Post cryopreservation viability after different storage time in LN₂. G) Representative images of Hoechst (all cells) and propidium iodide (PI) (dead cells) for control group (top), laser warming group (middle), and convective warming group (bottom). A–D) HDFs. E–G) UCBSCs. Scale bars are 200 µm. Data points represent mean ± s.d. For (A,B,D–F), n = 5; for (C), n = 4. A paired one‐way ANOVA and Tukey‘s post hoc was used for statistical analysis. For the significance symbols: ns, p > 0.05, * p < 0.05, ** p < 0.01, *** p < 0.001.