My company recently moved to a new building, where procedures are somewhat different. Our cell stocks are now located in the basement and my lab is on the 4th floor. As the cells are stored in nitrogen, company rules obligate us to transport the cells via a route that takes about 5 minutes to get back to the lab.
For convenience, I transported my PC12 cell aliquots in buckets of watery ice. I assumed that the cells would suffer minimally from the transport as it's just a short trip. However, I noticed that when I take the cryovials from the nitrogen stock, the medium in which the cells are frozen is yellow, and upon arrival at the lab the medium has already turned pinkish-purple. This is a pretty big difference.
The last time I transported my cells like this, the cell survival rate was pretty low. The time I started up new cells before the last time, I still had some aliquots in the -80 freezer and using these vials, the survival rate was much higher. The trip from the -80 freezer to the culture lab is not even a minute, and I put the cells on ice like I do when getting my samples from the nitrogen stock in the basement.
I was wondering: as the cells are frozen in culture medium (10% FBS, 1% pen/strep) + 10% DMSO, could the 5 minute walk with my cells on ice from the basement to the lab already cause the cells to die that rapidly?