FIG. 2.

Cell stretching in 2D affects cell orientation and cytoskeletal development, showing directional dependency. C2C12 myoblasts were cyclically stretched at 7% and 0.5 Hz in horizontal direction on membranes with micropatterned fibronectin lines. Staining with actin is shown. (a) Unpatterned (homogeneous [HS]), unstretched control had less well-developed actin fibers. (b) Stretching of unpatterned cells developed actin stress fibers oriented at an average angle of 72° (cyclic tensile strain [CTS]). (c) Patterned but not stretched cells showed actin fibers oriented along the fibronectin line pattern. (d) Stretch applied parallel to the patterned cell direction induced irregular cell orientation and formed actin stress fibers oblique to the strain direction (average actin fiber orientation of 48°). (e) Stretch applied to 45° of patterns caused an average actin fiber orientation of 52°. (f) Perpendicular stretch induced actin fiber orientation of 91°. Scale bar=50 μm. Reprinted with permission from Elsevier (Ahmed et al.).⁴⁶