Figure 8.

Performing chemical exposure directly on cells encapsulated in agarose chips allows for analysis of rapidly repaired DNA damage. H₂O₂ or SIN-1 treated cells and nontreated controls were compared. (A) CometChip repair kinetics of HepG2 cells treated with 30 μM of H₂O₂. Treatment and repair is performed on-chip. (B) Comparison of on-chip versus off-chip CometChip dose response in H₂O₂ treated cells. For on- chip experiments, statistically significant increases in DNA damage were observed at all doses. The average of the experiments shown in Figure 5E is plotted. For off-chip experiments, there is a ∼40 min lag time prior to comet analysis and statistical significance was observed at a dose of 200 μM. (C) Comparison of on-chip versus off-chip CometChip dose response in SIN-1 treated cells. For on-chip experiments, statistically significant increases in DNA damage were observed at 4 mM and above. For off-chip experiments, there is a ∼40 min lag time prior to comet analysis and statistical significance was observed at 30 mM and above. (D) Dose response for H₂O₂ treated spheroids, consisting of the average of the experiments shown in Figure 5F. A statistically significant increase in DNA damage was observed at 75 μM and above. On-chip CometChip results from B are replotted on same graph for comparison. (E) Dose response for SIN-1 treated spheroids. A statistically significant increase in DNA damage was observed at 2 mM and above. On-chip CometChip results from C are replotted on same graph for comparison. (F) SpheroidChip repair kinetics of HepG2 spheroids treated with 100 μM of H₂O₂. Treatment and repair is performed on-chip. Statistical analysis was performed with a one-way ANOVA with post hoc analysis using Dunnett’s multiple comparison test, *P < 0.05.