Question: What steps should be taken if gel is observed while processing post-storage fixed samples in the Flex workflow?
Answer: On rare occasions, minor gel formation can be observed during post-storage processing of -80°C stored samples post-fixation. This can appear as a much larger than expected cell pellet. We have not observed this phenotype related to specific sample types or length of time during storage.
If samples are carried forward with gel, there may be an impact on assay sensitivity and increased sample loss. With that in mind, if gel is observed after first centrifugation step in post-storage processing, we strongly recommend to perform the following steps:
- Remove as much of the liquid supernatant as possible but do not remove gel
- Resuspend sample with gel in 500 µl 0.5X PBS (No BSA, No RNase Inhibitor)
- Heat at 42°C 10 min
- Centrifuge 5 min at 850g in room temperature centrifuge
- Remove supernatant without touching the pellet
- Repeat steps 2-5 if gel is still present
- Resuspend pellet in Quenching Buffer B and proceed with workflow
Based on our limited testing, data from these samples will not be negatively impacted when performing the above steps to remove gel.
Products: Flex Gene Expression