Figure 1.

EPCs respond to substrate nanotopography. a) EPCs cultured on nanotopography exhibited morphological alterations when cultured on substrates with topographical features at 2 d. EPCs are aligned and elongated as measured by b) reduced circularity (*** p < 0.001) and reduced average angle of the major axis (*** p < 0.001) at 2 and 4 d. These morphological changes were observed after 4 h and stable throughout 6 d as well. c) Substrate nanotopography also reduces the proliferation of EPCs. Growth rates were reduced in EPCs cultured on nanotopography when compared to those cultured on flat surfaces. The doubling time was increased from 16.2 to 20.9 h. The reduced proliferation was verified by reduced frequency of cells in S-phase as determined by a BrdU incorporation assay at 2 and 4 d (*** p < 0.001). The direction of the linear nanotopographic features is indicated by the arrow. Scale bars in (a-phase) and (a-SEM) are 100 and 5 µm, respectively.