Effects of micropost spacing and stiffness on cell motility

Microfabrication processes enable the biophysical control of cellular environments at the micro- and nanoscale. The mechanical properties of arrayed microposts have been demonstrated to influence diverse cellular functions including cell motility, yet the cellular response to changes in micropost spacing remains unclear. In this work, a microfabricated post array with variable spacing and stiffness was constructed to investigate the effects of these biophysical factors on cell motility. Over a length of 675 m, the spacing between arrayed microposts decreased from 6 to 2 m in a single direction, corresponding to an average spacing decrease of 40 nm from post-to-post. Simultaneously, the radii of 7 m-high microposts were decreased from 2 to 1 m, resulting in a decrease in micropost stiffness from 50 to 5 nN/ m, respectively. Over the course of 18 h studies, bovine aortic endothelial cells (BAECs) seeded on the microfabricated post array migrated for an average of 9.6 7.3 m in the direction of decreasing interpost spacing, opposite the direction of durotaxis. By the end of the studies, 61 of seeded BAECs exhibited displacement in the direction of decreasing interpost spacing. The experimental results suggest that the spacing between microposts can be a determinant factor of cell migration direction in the design of micro- and nanotopographic cellular platforms.