Figure 4: Vitamin E prevents oxidative stress-induced repair failure.

(a) BS-C-1 cells were loaded for 24 h with 200 μM α-tocopherol or Trolox. Cells were laser wounded in PBS-containing calcium, in the presence or absence of 1 mM hydrogen peroxide (H₂O₂). Images of cells were captured before (0 s) and after injury (30 s and 300 s), red arrows indicate injury sites. (b) BS-C-1 cells not wounded but exposed to H₂O₂ (cyan dots), displayed nominal dye uptake in the laser assay. Cells wounded in the presence of H₂O₂ (red triangles) showed significantly (P<0.01; n=12) more dye influx than wounded cells not exposed to this oxidant challenge (black dots). Cell treatment with α-tocopherol (green squares) or Trolox (blue diamonds) significantly (P<0.01; n=17) decreased dye entry into oxidant-challenged cells. (c) BS-C-1 cells were laser wounded in the presence of 5 mM thimerosal (blue triangles). This oxidant significantly (P<0.01; n=12) increased dye uptake relative to untreated controls (black dots), to approximately the same level as cells injured in the absence of Ca²⁺ (red squares). (d) HeLa cells were pretreated 24 h with 200 μM α-tocopherol (green squares) or Trolox (blue diamonds), or 1 mM vitamin C (cyan triangles). Cells pretreated with antioxidants had significantly (P<0.05; n=17) less dye influx after laser injury than control, untreated cells (red dots). (e) HeLa cells were assessed for membrane repair immediately (less than 15 min) after addition of α-tocopherol (green squares), Trolox (blue diamonds), or vitamin C (cyan triangles) to the wounding solution. Only cells injured in Trolox displayed a significant (P<0.001; n=17) decrease in dye influx compared with untreated cells. Scale bars 20 μm.