Where are the validated stopping points in the Visium CytAssist Spatial Gene Expression for FFPE workflow?

Question: Where are the validated stopping points in the Visium CytAssist Spatial Gene Expression for FFPE workflow?

Answer: Below are a list of validated stopping points during tissue and library preparation:

1. After sectioning: Tissue Slides with FFPE tissue sections placed and dried for 3 hours at 42°C, can then be stored in a room temperature desiccator for up to 2 weeks.
2. During Visium CytAssist Gene Expression for FFPE assay: 
   • The workflow occurs over two days. The first day includes tissue Staining and overnight Hybridization. The second day includes completing the on-slide RTL and off-slide library construction steps.  
     • If done continuously, the first day is estimated to take ~5 hours (not including imaging time needed), and the second day is estimated to take ~6 hours.
   • Multiple stopping points have been built into both days of the workflow to maximize flexibility. Please refer to the Visium CytAssist protocols for specifics regarding storage conditions at each of these stopping points.

     1. After completing H&E Staining and coverslip mounting, slides can be stored laying flat in a container at 4°C, in the dark for ≤24h.*

     2. After completing H&E imaging coverslip removal and slide drying, slides can be stored in a slide mailer or 50ml centrifuge tube at 4°C, in the dark for ≤2 weeks. Ensure that slides don't come into contact with one another, this may require multiple tubes/mailers to be used.*

     3. After completing Post-Ligation Washes, samples can be stored at 4°C for ≤24h.
     4. After completing Probe Extension, samples can be stored at 4°C for ≤24h
     5. After completing Pre-Amplification SPRIselect Cleanup, samples can be stored at 4°C for ≤72h or at -20°C for ≤4 weeks.
     6. After completing Sample Index PCR and SPRIselect Cleanup, samples can be stored at -20°C for long-term storage.

*Storage of IF stained tissue sections pre or post imaging have not been tested and therefore are not currently supported.

Answer: Visium CytAssist for FFPE