Investigation on the Effects of Isotropic Nanopore Array with Low Aspect Ratio on the Cell Migration and Adhesion

Abstract

Cell migration plays pivotal roles in embryonic development, wound healing and immunes responses. During the cell migration, the cells interact with their extracellular matrix; specifically, the ECM provides structural support to the cells and induces the cells to generate cell signals that are capable of affecting various cell behavior such as cell morphology, spreading, polarization and adhesions, which in turn influencing migratory behavior of the cells. Thus, various properties of the ECM could affect migratory behavior of the cells significantly; many researchers employed various engineered surfaces which mimic properties of the ECM to investigate the ralationships between the ECM properties and cell migration. In our previous study, we adopted concept of adherable area of the isotropic nanopore-array surface firstly and found that reduced adherable area of the nanopore-array with high aspect ratio(i.e., HAR) promoted migration speed of the cells by inducing the cells to form immature focal adhesions, which enabled easier disassembly of the adhesions, compared to mature focal adhesions. However, in the previous study, we could not observe the effects of increased adherable area of the nanopore surface on the cell migration and adhesion, because we only employed nanopore-array surface with HAR previously. Thus, in this study, employing the nanopore-array surface with low aspect ratio(i.e., LAR), we investigated the effects of increased adherable area of the nanopore surface on the cell migration adhesion. The isotropic nanopore-array with HAR and LAR surfaces were fabricated by two-step anodizing processes of aluminum. After fabricating the nanopore surfaces with HAR and LAR, we firstly found that the cells on the LAR nanopore surface adhered to the pores entirely, which means that the LAR nanopore surface provided the cells with higher adherable area than flat surfaces. The cells exhibited promoted migration speeds on both HAR and LAR nanopore surfaces, though the HAR and LAR nanopore surfaces provided the cells with reduced and increased adherable area, respectively. We also found that adhesion strength between the cells and HAR, LAR nanopore surfaces was lower than the cells on the flat surfaces. Finally, quantitative analysis of focal adhesions formed in the cells were conducted to further investigate the effects of the LAR nanopore surfaces on the formation and maturation of the focal adhesions; the cells on the LAR nanopore surfaces formed immature focal adhesions mostly, though the LAR nanopore surfaces provided the cells with increased adherable area. These results suggest that increased adherable area of the LAR nanopore surfaces induced the cells to form many and immature focal adhesions in the cells, which enables the cells migrate faster than the cells on flat surface. The investigation in this study could give the comprehensive knowledges about the effects of nanopore-array with low aspect ratio on the cell migration and adhesion.