PDMS Elastic Micropost Arrays for Studying Vascular Smooth Muscle Cells

This paper describes the design, modeling, fabrication and characterization of a micromachined array of high-density 3-dimensional microposts (100×100) made of flexible material (silicone elastomers) for use to measure quantitatively the cellular traction force and contractile events in isolated vascular smooth muscle cells (VSMCs). The micropost array was fabricated with diameters ranged from 3 to 10 μm, with edge to edge spacing of 5, 7 and 10 μm, and with a height to diameter aspect ratio up to 10. VSMCs exerted larger basal traction forces when they were grown on stiffer micropost arrays. These basal traction forces were 80% larger in control VSMCs than in VSMCs in which integrin linked kinase (ILK) was knocked down using shRNA. The addition of Angiotensin II (ANGII) led to VSMC contraction as evidenced by an increased traction force exerted on the microposts under the cell. This ANGII induced contractile response and change in traction force on the microposts was not observed in VSMCs lacking ILK. Following treatment of VSMCs with Cytochalasin D to depolymerize the actin cytoskeleton, the VSMCs exhibited relaxation that was apparent as a significant reduction in the measured traction force exerted on microposts under the cell. Overall, this study demonstrates the usefulness of micropost arrays for study of the contractile responsiveness of VSMC and the results indicate that ILK plays a critical role in the signaling pathways leading to the generation of substrate traction force in VSMC.