Question: Can I freeze a cell pellet or whole blood?
Answer: Whole blood or cells/nuclei should not be frozen. Freezing cells without a cryoprotectant can compromise cellular membranes and negatively impact cell viability.
Isolated cells can be cryopreserved by following one of the following protocols :
- Fresh Frozen Human Peripheral Blood Mononuclear Cells for Single Cell RNA Sequencing demonstrated protocol (CG000039).
- Fresh frozen human-mouse cell line mixtures for single cell RNA sequencing(CG00014)
Key points highlighted in this protocol:
- Use a cryoprotectant such as DMSO as indicated; this will preserve cell membrane integrity and cell viability.
- It is important to follow the slow-freeze recommendations; freezing cells too quickly may impact cell viability. Cells should be slowly frozen at -80C in an isopropanol bath or a cell freezing container(e.g., CoolCell FTS30).
- After slow freezing at -80C for 4 hours, cells should be moved to liquid nitrogen.
- Freeze cells at the appropriate cell density, cells are not happy at low densities, this can impact cell viability.
- Follow drop-wise thawing procedure; this step is important when trying to preserve sensitive cell types.
Isolated nuclei should not be frozen as pellets and should be used immediately for downstream 10x single-cell applications for best results.
Products: Single Cell Gene Expression, Single Cell Immune Profiling, Single Cell ATAC, Single Cell Multiome ATAC + GEX