A comparative atomic force microscopy study on living skin fibroblasts and liver endothelial cells.

Atomic force microscopy (AFM) has been used to image a wide variety of cells and has proven to be successful in cellular imaging, by comparing results obtained by AFM with SEM or TEM. The aim of the present study was to investigate further the conditions for AFM imaging of living cells and compare the results with those obtained by SEM. We chose to image skin fibroblast and liver sinusoidal endothelial cells of two different sources, because these cells have been well described and characterized in earlier studies. AFM imaging of living cells mainly reveals submembranous structures, which could not be observed by SEM. This concerns the visualization of the overall cytoskeletal architecture and organelles, without the necessity of any preparative steps. The AFM study of living cells allows a time lapse study of dynamic changes of the actin cytoskeleton under the influence of the cytoskeleton-disturbing drug cytochalasin B in cells that can be followed individually during the process. However, softer samples, such as the fenestrated parts of living rat liver sinusoidal endothelial cells in culture could not be visualized. Apparently, these cell parts are disrupted due to tip-sample interaction in contact mode. To avoid the lateral forces and smearing artefacts of contact mode AFM, non-contact imaging was applied, resulting in images of higher quality. Still, endothelial fenestrae could not be visualized. In contrast, contact imaging of immortomouse liver sinusoidal endothelial cells, which are devoid of fenestrae, could easily be performed and revealed a detailed filamentous cytoskeleton.