Imaging of the membrane surface of MDCK cells by atomic force microscopy

Abstract

The membrane surface of polarized renal epithelial cells (MDCK cells) grown as a monolayer was imaged with the atomic force microscope. The surface topography of dried cells determined by this approach was consistent with electron microscopy images previously reported. Fixed and living cells in aqueous medium gave more fuzzy images, likely because of the presence of the cell glycocalix. Treatment of living cells with neuraminidase, an enzyme that partly degrades the glycocalix, allowed sub-micrometer imaging. Protruding particles, 10 to 60 nm xy size, occupy most of the membrane surface. Protease treatment markedly reduced the size of these particles, indicating that they corresponded to proteins. Tip structure effects were probably involved in the exaggerated size of imaged membrane proteins. Although further improvements in the imaging conditions, including tip sharpness, are required, atomic force microscope already offers the unique possibility to image proteins at the membrane surface of living cells.

The electrical resistance breakdown assay determines the role of proteinases in tumor cell invasion

“…AFM reconstructs an image of a surface from x, y, and z data to develop a three-dimensional topography of any surface at a nanometer level (31). The procedure for AFM imaging of different biological samples such as MDCK cells in the contact and tapping modes has been described elsewhere (16,17,22,30). For surface scanning, C7 cells were seeded on the reverse surface of the filter membrane, and melanoma cells were added to the upper medium (as described in Cells and cell culture), separated from C7 cells by the filter membrane (no physical contact).…”

Structural and Mechanical Heterogeneity of the Erythrocyte Membrane Reveals Hallmarks of Membrane Stability

“…Considering the fact that the glycocalyx might hamper detection of fine topographic features on the extracellular face and that the cytoplasmic membrane face is expected to be rather crowded with membrane skeleton elements, 16 Certainly, the fact that membrane skeleton junctions are rather preserved all through the plasma membrane, even after spectrin removal, confirms their functionality as underpinning of the skeleton network. Evaluation of the mechanical properties on both sides of the erythrocyte membrane was assessed from the corresponding elasticity and deformation maps.…”

Atomic Force Microscopy Imaging of Living Cells

“…The Auto Tune function of the microscope can help find the proper working frequency [11]. As cells are extremely soft substrates, the best lateral resolution that can be expected is about 10 nm [12][13][14]. Both of these modes have been shown to provide good results in live-cell imaging (Figure 2A), but more relevant results are obtained when combined with light microscopy ( Figure 2B).…”