Effects of cyclic stretch on cell reorientation.

<p>Phase-contrast images of the cells in the static condition (<b>A</b>) or in response to cyclic stretch (20% in strain, 30 cycle/min) (<b>B</b>). An arrow indicates stretch direction. Histograms of the orientation response of the cells in the static condition (<b>C</b>) or to 2 h uniaxial cyclic stretch (<b>D</b>). Images of the unstretched and stretched cells were obtained at 0.5 h, 1 h, and 2 h after the onset of cell stretching. After the cell angles were measured, the angles were binned into 19 groups for every 5°: 0°, 1–5°, 6–10°, …, 81–85°, and 86–90° (<b>C</b> and <b>D</b>). Total cell number (frequency) was set as 100% and the frequency in each group was expressed relative to the total cell number. (<b>E</b> and <b>F</b>) The mean and standard deviation (SD) of the cell orientation at each time point. The decreasing SD of angles indicates that the cells were aligning in a direction which was almost perpendicular to the direction of applied stretch. Bar graph represents means ± SD (across 5 different trials). Data were analyzed with one-way repeated-measure ANOVA followed by the Bonferroni test. *: Significantly different (P<0.05) from the unstretched control (time 0) value (n = 5).