Hi Idyil, freezing cells and maintaining their properties after thawing is always tricky.

But, if the Millipore technical service recommends that you use a certain protocol to freeze back their cells, I think you should follow it.

Usually cell lines are frozen in 10% DMSO, 90% FBS. The serum in this freezing protocol can differentiate stem cells.  

Dear Dr. Stefansson, thank you for your answer. I wanted to know whether it is the same composition with growth medium w/ DMSO but just a commercial solution.  The problem is that they do not mention anything on the neural stem cell line data sheet about freezing. I thought commercial cell lines should include all necessary information about maintaining cells. I ran into the commercial millipore freezing medium when I googled how to freeze neural stem cells. Since it is a commercial solution, the recipe is not available. 

Thanks again!

Hi It is depending on whether you want to maintain the cells as stem cells? If yes, you should not add FBS in your freezing medium. Then you should use your used medium (called conditioned medium) + DMSO 7.5 %. 

For no stem cells, usually we use FBS 45%, Medium 45% and 10% DMSO or Some lab in Korea, they use 40% FBS, 40% Medium and 20% DMSO. Both are ok too. So check yourself which one you prefer for your cells. Trials and errors, then decide for you. Good Luck. 

You could try the following guide from PromoCell

https://www.promocell.com/blog/primary-cell-culture-guide-thawing-freezing-subcultivation-poster/