Figure 4. Stretch response of single smooth muscle cells.

(a) Sideview schematic of cell adhered to micropost substrate (mPAD) in unstretched condition. The magnitude and direction of the deflections of the microposts are used to determine the forces exerted by the cell. (b) As the underlying mPAD substrate undergoes biaxial stretch, so too does the adherent cell. (c) Micrograph of SMC on an mPAD substrate with an effective micropost spring constant for small lateral deflections of 22 nN/μm. Red arrows show measured cellular forces, and white trace shows the outline of the cell. (d) Change in cellular forces upon application of 8% strain. (e) Strain profile applied to mPAD substrate results in the increases in cellular force shown by the circles in (f). (g) Force-strain curve showing viscoelastic response and recovery corresponding to that observed in the microtissues. The red curves in (f,g) are a fit using solely the cellular components of the model shown in Fig. 3.