Nanotopographic surfaces alter actin dynamics in primary rat astrocytes

Astrocytes, the non-neuronal cells of the brain, are morphologically and functionally diverse. Their functional roles range from maintaining brain homeostasis to modulating neuronal communication. Astrocytes also display morphological phenotypes ranging from pancake shaped (immature "polygonal" cells) to star shaped (mature "stellate" cells). In all cases, astrocytes' roles are facilitated by their regulation of ion and water molecule flux across their membranes, which requires dynamic reorganization of the cytoskeleton. Our previous work discovered that astrocytes use dynamic actin waves to sense chemophysical cues corresponding to realistic changes in the brain's microenvironment. Here we build off that work using biocompatible, nanotopographic surfaces as mechanical "triggers" to perturb astrocytic actin dynamics. We use live confocal microscopy to capture dynamics in cells transduced with actin-GFP and grown on either control or nanotopographic surfaces. Then we employ an optical flow algorithm to analyze changes in actin dynamics. We characterize astrocytes' responses to these mechanical cues and use micron-scale alterations in actin dynamics to understand the cellular-level response to changes in the extracellular microenvironment.