If tissue was fixed in 4% PFA then cryoprotected in 30% sucrose, are you able to wash and switch to FFPE processing instead of blocking frozen in OCT?
Yes, it is possible to process tissue for FFPE after cryoprotection in sucrose, with some additional steps:
- Wash the sucrose-cryoprotected tissue thoroughly in several changes of PBS to remove all traces of sucrose. Sucrose can interfere with tissue processing and embedding if not removed.
- Post-fix the tissue in 10% neutral buffered formalin for at least 24 hours. This ensures adequate cross-linking and preservtion for FFPE.
- Process the fixed tissue using standard FFPE processing protocols - dehydration through graded alcohol and xylene, infiltration with molten paraffin wax, and embedding into wax blocks.
- The initial PFA fixation allows switching methods, but post-fixing in formalin ensures optimal tissue preservation and cross-linking for FFPE sectioning.
- Take care to orient the tissue properly during embedding into the wax block.
Great answer Salah,
Is the staining quality (fluorescent signals for example) affected?
Thanks.
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