In short
Cell banking freezes cells in liquid nitrogen at about −196°C with cryoprotectants to preserve viability for future use. Quality depends on the cooling process, temperature monitoring and traceability systems.
What a good banking system needs
Continuous temperature control and logging, backup nitrogen and power, traceable sample identification, contamination testing before storage and documentation recording source, timing and quality results.
Questions to ask before banking
Ask about contract duration, annual fees, what happens if the provider ceases operations, access rights, cross-border transfer capability and quality documentation for each lot.