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Antibiotics in Cryoprotectant medium? - (Aug/17/2007 )

Can antibiotics (Penicillin/Streptomycin) be used in the cell freezing medium for mammalian cells? If not, why?



If you are using pen/strep to keep down something that may or may not be contaminating your cells, I would recommend splitting off a separate flask and removing the pen/strep to see if it is clean. (Also you will need to test for mycoplasma as pen/strep is not going to protect you from that) I never freeze things in antibiotic, as I feel that the extra stresses are best to avoid during freeze and thaw. So, I figure if I am not going to transfect in the presence of antibiotic, I am not going to freeze down in the presence of antibiotic. If you need to freeze in antibiotic, I would suggest freezing several vials, then thawing one right away to see if the culture either dies or goes through any noticeable changes.



we freeze our primary embryonic fibroblast line in growth media with antibiotics and 10% DMSO- never had any probs.


I was taught to freeze cells without antibiotics. However, one day I set up the wrong media (with antibiotics) as my freezing media and decided to go ahead and try it. After thawing I saw no significant difference when compared to cells frozen earlier without pen/strep. I now routinely freeze with the pen/strep. The little bit of extra stress this may place on your cells is worth the protection from contamination (in my opinion).