Figure 4:

Analysis of metabolic activity and morphology of stem cells in an oxidative environment. (a) Schematic demonstrating the procedure to assess the metabolic activity of stem cells seeded in the collagen gel. The cells were subsequently exposed to 200 μM H₂O₂ for 2 h. The H₂O₂ solution was then replaced with H₂O₂-free fresh culture media either for measurement of metabolic activity or for further incubation for 1 day or 4 days at 37 °C, 5% CO₂. (b) The overall metabolic activity per initial number of cells measured at different time points following exposure to 200 μM H₂O₂ for 2 h. The overall metabolic activity was expressed as the fraction of metabolically active cells with respect to the metabolic activity of groups treated in the same way but not exposed to H₂O₂. The values and error bars represent the average percentage of metabolic activity and standard deviation of three individual samples per condition, respectively. (c) The inverse of cell shape index of stem cells of various conditions on Day 4 after the H₂O₂ exposure for 2 h. The values and error bars represent the average percentage of metabolic activity and standard error of 50 individual cells per condition, respectively. * represents the statistical significance in the difference of values between the indicated conditions (* p < 0.05). The numerical values noted above the bars are the estimated amount of EGCG released from the particles. The amount of EGCG released was estimated using the in vitro release profile of EGCG obtained in Figure 1b. The initial loading of EGCG was 3.5 μM.