Fractal analysis of cell boundary ultrastructure imaged by atomic force microscopy

Abstract

Fractal analysis has been widely used to determine the complexity of irregular shapes of various natural objects including biological systems. Here we report an investigation into the nature of the cell boundary nanostructure (less than 200 nm in thickness) in an aqueous environment using atomic force microscopy. The box-counting method revealed the fractal nature of detailed contours of cells cultured on a solid substratum. The fractal dimensions (Df) of individual cells of the human epithelial cell line MCF10A converged on a narrow range (Df = 1.352 ± 0.044) despite their morphological diversity. Treatment with cytochalasin D, an inhibitor of actin polymerization, was shown to decrease both the ruggedness and the Df of cell boundaries. These findings suggest that the Df value is a useful parameter for describing the complexity of cellular ultrastructure dependent on the actin cytoskeleton.