Invitrogen™ Annexin Binding Buffer (5X), for flow cytometry

Trypsinization or mechanical scraping of cells temporarily disrupts the plasma membrane, allowing annexin V to bind phosphatidylserine on the cytoplasmic surface of the cell membrane and thus leading to false positive staining. Allow the cells to recover for about 30 minutes in optimal cell culture conditions and medium after trypsinizing/scraping so that they can recover their membrane integrity before staining. For lightly adherent cell lines, such as HeLa and NIH 3T3, another option is to use non-enzyme treatments like Gibco Cell Dissociation Buffer (Cat. No. 13151014).

Annexin V staining is not typically used in imaging experiments; it is a better reagent for flow cytometry analysis. All cells will stain to some extent, so it can be difficult to distinguish a relatively bright annexin V-stained cell from a dimmer non-apoptotic cell. Caspase activation, detected using our CellEvent Caspase 3/7 or Image-iT LIVE Caspase detection kits, is a better method for detecting apoptosis in an imaging assay.

Trypsinize first and then allow the cells to recover about 30 minutes in optimal cell culture conditions and medium before staining with annexin V conjugates. Trypsinization or mechanical scraping of cells temporarily disrupts the plasma membrane, allowing for annexin V to bind phosphatidylserine on the cytoplasmic surface of the cell membrane and thus leading to false positive staining. For lightly adherent cell lines such as HeLa and NIH 3T3, you could use a less harsh (non-enzymatic) dissociation product like Gibco Cell Dissociation Buffer (Cat. No. 13151014).

Yes, this is possible. We have established protocols for annexin V staining combined with intracellular staining of lymphocytes that can be found here. The most important step is to leave some binding buffer in the suspension when fixation is started. Compared to staining of live cells, the intensity of the annexin V signal may be somewhat reduced.