Directing Osteoblastic Cell Migration on Arrays of Nanopillars and Nanoholes with Different Aspect Ratios

To realize highly directional guidance for cell migration, both micro− and nano−scale topographies were studied to better understand and mimic the complex extracellular matrix environment. Polydimethylsiloxane based platforms with micro− and nano−topographies were developed to systematically study their guidance effects on cell migration behaviors. Compared to flat surface or grating as microtopography, nanotopographies such as nanoholes and nanopillars could promote the generation of filopodia and extension of long protrusions with increased migration speed for MC3T3-E1 cells. Although cells on the grating structures showed lower migration speed, more directional cell migration was achieved due to its anisotropic topography compared to nanohole or nanopillar arrays with isotropic structures. To further enhance the cell migration directionality, the nanotopographies were patterned in grating arrangements and the results showed that both nanoholes and nanopillars in grating arrangements introduced more directional cell migration compared to gratings. The effects of physical dimensions of nanotopographies on cell migration were studied and the results showed that there were less cell elongation and less directional migration for nanoholes in grating arrangements with increasing depth of nanoholes. However, nanopillars in grating arrangements showed more cell elongation, more directional migration, and higher migration speed with increasing height of nanopillars. Platforms with nanopillars in grating arrangements and large height could be used to control cell migration speed and directionality, which could potentially lead to cell sorting and screening.