I want to do a cell migration study for around 4 hours and need to fluorescently label the cells with a dye. What do you recommend?
Calcein, AM and FDA (fluorescein diaceate) are examples of some dyes used for this application. Since these dyes are not incorporated or covalently attached to any cellular components, they may have a short retention time as some cell types may actively efflux the dye out of the cells. The CellTracker and CellTrace dyes include either a mild thiol-reactive chloromethyl group or amine-reactive succinnimidyl ester group to allow for covalent binding to cellular components, providing for better retention. As with any reagent, one should empirically determine retention times for the cell type used.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
Is DAPI a good live-cell nuclear label?
DAPI is considered a semi-permeant/impermeant nucleic acid stain. Staining of nucleic is dependent upon the cell line in its performance. Some cell lines will label with DAPI, others not at all, and others label inconsistenly. Instead, we recommend using either Hoechst 33342 or Hoechst 33258, which have the same wavelength and binding mode as DAPI (at the A-T minor groove) but are readily cell-permeant.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
I want to label the nuclei of live cells and track them over time. Can I use DAPI for this?
We do not recommend doing this. DAPI is considered to be a semi-permeant/impermeant nucleic acid stain. DAPI staining of live cells may be inconsistent. It is best used as a counterstain for fixed samples. Other cell permeable nucleic acid stains, such as Hoechst or the SYTO dyes may affect cellular function.
For mammalian cells, we recommend using the CellLight Nucleus transduction reagents, available in CFP, GFP and RFP. With these reagents, the cells are transduced overnight in a single labeling step and the next day the nuclei will fluoresce. The label may be retained for 3-5 days and should not affect cell function. Cytoplasmic cell tracking dyes such as the CellTracker dyes may also be used.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
I labeled my cells with Calcein, AM, but when I imaged the next day, there was no fluorescence from Calcein. Why?
Calcein, AM is a good choice for cell tracking and as a general cytoplasmic stain. However, it doesn't bind to anything and may be actively pumped out of the cells within a couple hours, which is likely what happened. The retention of Calcein within live cells is dependent upon the inherent properties of the cell type and culture conditions.
For long-term imaging, you may wish to consider a reactive cytoplasmic stains such as CFDA, SE or the CellTracker and CellTrace dyes.
Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.
Can the CellTracker dyes be fixed?
Yes, the CellTracker dyes react with any accessible thiol part of the protein and can be fixed. However, some CellTracker dyes may be attached to small metabolites that can leak from the cell following permeabilization. This can result in decreased fluorescence.
Find additional tips, troubleshooting help, and resources within our Cell Tracing and Tracking Support Center.