Structural actin analysis in primary rat cortical astrocytes predicts culturing nanotopography*

Astrocytes, long regarded as merely passive supporting cells of the brain, have been proven vital in brain informational processing. The ‘Tripartite Synapse’ concept has recently emerged whereby astrocytes modulate neuronal activity. For this to occur, astrocytes must be able to physically interact with both neurons and other astrocytes. Therefore, the morphology of astrocytes is vital to understand brain health and function. Actin, a cellular structural protein, has not been studied in astrocytes extensively. To this end, we grow astrocytes on different nanotopographic surfaces, and then fix and stain the cells with Phallodin-488. These fixed cells are then imaged using STED microscopy to obtain detailed images of the actin structure in astrocytes. We then use image processing methods to extract the filament organization in the astrocytes. We demonstrate that there exists a significant angle organization difference between astrocytic actin on different nanotopographies. These results illustrate the importance of actin as a predictor for environmental influences. We propose that additional co-culture experiments (neurons cultured with astrocytes) will reveal similar disparities at this actin level and may predict astrocytic modulation of neuronal activity.