We are looking to improve our cell culture productivity in CHO cells. We want to use imaging to inform our process choices and improve our cell health, viability and of course titer. What methods would you recommend?

Answer

There are a number of choices for evaluating the health of your cells using fluorescent imaging assays, from simple to complex. Understanding how healthy your cells are, and determining optimal timing for passage can improve productivity. A number of assays can help provide useful information.
•To evaluate viability, the use of a cell-impermeant DNA binding dye may be used, such as the Image-iT DEAD Green Viability stain where dead cells will fluoresce green. A dead cell stain can be combined with a marker of cell vitality that measures esterase activity, Calcein AM, as seen with the LIVE/DEAD Cell Imaging Kit where active cells fluoresce green and dead cells fluoresce red. Probably the most simple method uses ReadyProbes Dead Cell stains; these are ready-to-use reagents for fluorescent imaging that have been simplified for use (add 2 drops from the dropper bottle per mL of sample and image).
•Cell proliferation analyses can be helpful for assessing cell growth. A very useful method uses incorporation of a thymidine analog, EdU, for direct measurement of cells in S-phase using click chemistry. The Click-iT Plus EdU assays are fully compatible with fluorescent proteins.
•You may want to know if your cells are dying via apoptosis, the CellEvent Caspase 3/7 Green reagent is a no-wash assay compatible with labeling in media, the green fluorescence intensity increases with caspase activity.