The effects of continuous and discontinuous groove edges on cell shape and alignment.

Nanofabricated model surfaces and digital image analysis of cell shape were used to address the importance of a continuous sharp edge in the alignment of cells to shallow surface grooves. The grooved model surfaces had either continuous or discontinuous edges of various depths (40-400 nm) but identical surface chemistry and groove/ridge dimensions (15 microm wide). Epithelial cells were cultured on the model surfaces for 10 and 24 h. Fluorescence microscopy combined with image analysis were used to quantify cell area and alignment and to make cell shape classifications of individual cells. The degrees of alignment of cells and the percentages of elongated cell classes increased with groove depth on samples with continuous grooves. Two main differences, with regard to cell response, were observed between the continuous and discontinuous grooved surfaces. First, significantly fewer cells aligned to surface grooves with discontinuous edges than to grooves with continuous edges. Second, there were lower percentages of the elongated cell classes on discontinuous grooves than on continuous ones. We concluded that grooved surfaces with continuous edges are more potent in aligning and inducing elongated cells. The results from the present study suggest that a mechanism of alignment involving orientation along a continuous edge is likely.