Comparison of fixed and living liver endothelial cells by atomic force microscopy

We have investigated living and glutaraldehyde fixed liver endothelial cells (LEC) by atomic force microscopy (AFM). In living cells, resolution is generally poor compared with what we have found with the same cells after fixation. LECs possess arrays of pores or fenestrae in their membrane, grouped in so-called sieve plates. In living cells these sieve plates could not be resolved by AFM. However, they could be picked up easily in fixed cells. The size of these fenestrae is around 200 nm. The difference in resolution can be explained by the difference in softness in both cases, as measured by taking and analyzing force curves. Typical values of the elastic modulus are around 2 kPa for the living cell and more than 100 kPa for the fixed cell.