liquid nitrogen in cell culture - (Jan/07/2010 )
i will be ordering some cells from sigma, coming in dry ice. i'll probably start working on these cells 24 hrs after they are shipped. in this time do they need to be transferred to liquid nitrogen or can they remain in the dry ice?
also, do you use liquid nitrogen or vapor phase nitrogen? where do you purchase it?
When I receive the cells, if the cells already half thawed, I'll just thaw and grow it. If the dry ice still there and the vial not thawed, i'll keep it in liquid N2 until I need it.
Some people prefer to store it in liquid N2, as it can maintain the temperature better. But some said vapor phase is better coz it needs less liquid N2 (you'll need a lot of N2 if you store cells in liquid N2. Not cheap for some low budget lab.) Some people find that storing in liquid increase the chance of contamination. But if you store in N2 vapor, you'll need to check the level of N2 more often to maintain it.
BOC is a common supplier of LN2.
Cells can remain at -80 ish for extended periods of time up to about 6 months before loss of viability really starts to show. You do not need to work with the cells immediately, they can be stored for a while before use.
Cells can be stored in both liquid and vapour phases of the nitrogen. The liquid is more prone to cross-contamination of cell lines by viruses and things that can get out of the tubes (mycoplasma too), but the risk is relatively small. The biggest problem with the liquid phase is that it creeps into the tubes (also the source of the cross-contamination) and creates a small explosion and bio-contamination threat when the tube is being extracted from storage.