Abstract
Cells elongate on a surface with nanogrooved (NG) patterns and align along that pattern. Although various models have been proposed for how this occurs, much remains to be clarified. Studies with fixed cells do not lend themselves to answering some of these open questions. In this study, the dynamic behaviours of living mesenchymal stem cells on an NG substrate with a 200 nm groove depth, an 870 nm ridge width and a 670 nm groove width were observed using time-lapse microscopes. We found that filopodia moved as if they were probing the surroundings of the cell protrusion, and then some cell protrusions invaded the probed areas. Cell protrusions that extended perpendicular to the NG direction tended to retract more rapidly than those parallel to the grooves. From these facts, we think that the retracting phase of cell protrusions play a rule in cell alignment along the NG patterns.