Choosing a cell type for imaging
Cells perform a multitude of functions within an organism, and their shape is highly correlated with their function, so it should come as no surprise that cells have a broad variety of shapes and volumes, levels of specific protein expression, and metabolic activities.
Consider native cell function and ease of manipulation
If your goal in imaging does not depend on using a particular cell type, it makes sense to choose a cell type in which your target is easy to image. For example, if you are studying a particular protein, a cell that contains a high level of that protein localized in the structure you are studying would be ideal. If you need to add your protein of interest to an existing cellular background, it would make sense to choose a cell type that can be transfected easily and that remains in good condition after transfection. If you want to label something involved in a metabolic pathway, it is in your interest to choose a cellular model that has a robust metabolic response.
Fibroblasts and epithelial cell lines can be good choices for cell structure staining
If you are studying the cytoskeleton, or other cellular structures in the cytoplasm like the Golgi complex, ER, or mitochondria, pick a cell line in which the nucleus does not predominate the volume of the cell. If the space between the nucleus and the plasma membrane is very small, it can be challenging to visualize cellular structures with fluorescence microscopy, as is the case with macrophage-derived cell lines such as RAW264.7 or MMMs. Cell lines derived from dermal fibroblasts are frequently imaged in wound healing studies because they exhibit robust filamentous actin that is easily stained and imaged. Epithelial-derived cell lines are popular for imaging cellular structures for several reasons: they are big enough that the nucleus doesn’t dominate the cell lumen; many show continuous actin filaments in a single focal plane; they are more physiologically relevant for many cancers than fibroblast-derived cell lines; and cell lines such as HeLa, A549, and MDCK are very well characterized, which gives the advantage of both proven protocols and a frame of reference for your experimental results.
Figure 1. A549, HeLa, ME180, and U2OS cells all exhibit very different staining patterns for the same set of fluorescent reagents due to differences in their morphology and metabolic pathways. All four cell types were stained with NucBlue Live® reagent after transduction with CellLights®Golgi-RFP and Mito-GFP reagents.
Often, your cell choice is a compromise
BPAECs, an endothelial-derived cell line, are often used because of their large cell bodies and flat shape, which makes imaging cellular structures easier, but they are not efficiently transfected if your aim is to image an overexpressed protein. Conversely, HEK293 cells are widely used for transfection but do not always work well for imaging because they do not adhere very tightly to the culturing surface—it’s hard to image a floating cell! Many times you will have to bypass a cell type that is ideal in one key way (because it has quite a few drawbacks) and instead choose a cell type that offers adequate characteristics in several categories (even though it’s not outstanding in any single parameter).