Question: Can Visium Gene Expression Slides be stored post-H&E staining?
Answer: Storage of Visium Gene Expression slides post-H&E staining before imaging is not currently a validated stopping point. Therefore, we strongly recommend following the stopping points provided in the Visium Gene Expression User Guide. To avoid imaging delays, optimize imaging parameters before beginning an experiment by leveraging the Imaging Test Slide in the Visium Accessory Kit.
However, if a delay cannot be avoided due to hand-off constraints or unexpected events, H&E stained tissue on Visium slides can be stored at 4°C in a sealed container for up to 24 hours before performing brightfield imaging or tissue permeabilization. Based upon limited in-house testing with a small number of tissue types, tissue stored at 4°C in a sealed container for 1 day performed equivalently to standard protocol controls. Extending storage time beyond 1 day showed a reduction in assay performance. Please keep in mind that this is not a supported stopping point due to the small sample size tested. Accordingly, depending on your tissue type and sample quality, you may see a reduction in assay performance compared to following the validated stopping points. Ensure the following conditions are met if introducing slide storage post-H&E staining or brightfield imaging:
- The slide should be stored in an airtight container at 4°C.
- The slide should be acclimated to room temperature (~5 minutes or longer if needed), and dry prior to imaging.
- If coverslip mounting is required for imaging, apply coverslip per demonstrated protocol recommendations and image post-1-day storage. Do not store slide at 4°C with a coverslip.