Effects of surface nano-topography on human osteoblast filopodia.

Anchorage-dependent cells growing over a substratum require stable adhesion areas on the surface for the next cellular activities. The adhesion is achieved by some contact points called focal adhesions. Because focal adhesions were distributed randomly, a trial to control the positions of focal adhesion with a specific order may cause interesting effects like as cytoskeleton rearrangement, which may induce and transfer new signals to the nucleus. Here, we cultured human osteoblasts over two sorts of nanopatterned surfaces with different pattern densities fabricated by using laser interference lithography and the nanoimprinting technique. Of the two nanopatterns, cells over the nanopattern with low pattern density showed relatively higher adaptation to the topography with guided filopodia protrusion. However, cells over the dense nanopattern showed difficulty in finding suitable paths for migration, as judged from the activities of filopodium formation and the presence of a shovel-like feature at the tip of each filopodium.