Figure 3

The effect of PEF on the extracellular matrix.

a Top ( Maisson’s Trichrome staining) enabled the identification of collagen-containing pixels and demonstrated significantly higher density within the PEF-treated areas of the skin. Lower panel shows the pixel-wise fiber directional analysis, enabled quantification of the local strength of collagen fiber alignment, which demonstrated reduced variance in fibers up to three weeks after PEF, but no significant difference in the directional variation within the PEF treated area two months after the treatment. b Secretion of new fibers to the PEF-treated area was detected by Herovici staining. c Quantitative analyses of fiber density in the center of PEF treated area were significantly elevated, starting with day 3 after PEF treatment and continuing up to 3 weeks after the treatment. Two months after treatment the fiber density of the PEF treated area was not significantly different from the control, untreated skin (*) p-val = 0.03; (**) p-val = 0.009; (***) p-val = 0.02. d Quantitative analyses showed no significant difference in fiber alignment, indicating no scar formation at the PEF-area. e Quantification of blue/red in the digitized Herovici stained slides shows significant increase of the blue staining (collagen type III) one week after the PEF. (*) p-val = 0.01. For each experimental point we analyzed at least 4 slides, each obtained from a different animal. f Young’s modulus change of the PEF treated skin in comparison to untreated control: An increase in Young’s modulus was observed 3 days and 1 week after PEF treatment of the skin.(*) p-val = 0.0048 (**) p-val = 0.0028 Five animals were used for each time point. In all plots, error bars show ± SEM. Statistical analysis was performed by first using one-way ANOVA for multivariate analysis and post hoc using Dunnett’s tests to assess significance between individual groups. Significance was set at P < 0.05.